Full text of "Bulletin of the Bureau of Fisheries"

See other formats

bdy.y -3

Division of Fishes,
y, i NttionaJ Museum

DEPARTMENT OF COMMERCE AND LABOR

BULLETIN

OF THE

BUREAU OF FISHERIES

VOL. XXIX
1909

GEORGE M. BOWERS

COMMISSIONER

WASHINGTON

GOVERNMENT PRINTING OFFICE

1911

rj^onian ins tituf>

OCT 21191

!\j % ^ ^

j^onal

CONTENTS.

Pages.

A REVIEW OP THE SALMONOID FISHES OP THE GREAT LAKES, WITH NOTES ON THE WHITEFISHES
OF other REGIONS. By David Starr Jordan and Barton Warren Evermann. (Issued

February 7,1911) 1-42

Infeuence of The EYES, ears, and OTHER ALLIED SENSE ORGANS ON the movements of
the dogfish, Mustelus canis (Mitcihll). By G. H. Parker. (Issued November 18,

1910) 43-58

Barnacles of Japan and Bering Sea. By Henry A. Pilsbry. (Issued February 17, 1911). . 59-84

The food value of sea mussels. By Irving A. Field. (Issued February 24, 1911) 85-128

The migration of salmon in the Columbia River. By Charles W. Greene. (Issued March

15, 1911) 129-148

Natural history of the American lobster. By Francis Hobart Herrick. (Issued July

13. I911) 149-408

Anatomy and physiology of the wing-shell Atrina rigida. By Benjamin H. Grave.

(Issued May 4, 1911) 409-440

General index 441-445

ILLUSTRATIONS.

J-

PLATES.

Review of salmonoid fishes of Great Lakes: Facing page.

Plate I. Lake trout, Mackinaw trout (Cristivomer namaycush) x

II. Lake Huron herring (Leucichthys sisco huronius) 42

III. Bloater of Lake Michigan (Leucichthys johannae) 42

IV. Blackfin of Lake Michigan (Leucichthys nigripinnis) 42

V. Cisco of Lake Michigan (Leucichthys hoyi) 42

VI. Common whitefish of Lake Erie (Coregonus albus) 42

VII. Menominee whitefish, round whitefish (Coregonus quadrilateralis) 42

Barnacles of Japan and Bering Sea:

Plate VIII. (1-4) Scalpellum rubrum. (5-7) Conchoderma auritum 61

IX. (1) Scalpellum stearnsi. (2-4) Scalpellum gonionotum. (5-7) Scalpellum

weltnerianum 84

X. Scalpellum japonicum 84

XI. (1-3) Scalpellum japonicum biramosum. (4, 5) Scalpellum molliculum.

(6, 7) Octolasmis orthogonia. (8, 9) Heteralepas, species undetermined.. 84

XII. (1-3) Heteralepas vetula. (4) Balanusrostratusapertus. (5) Balanus callisto-

derma. (6) Balanus rostratus. (7) Balanus rostratus apertus 84

XIII. ( 1, 2) Balanus rostratus apertus. (3-7) Balanus hoekianus. (8, 9) Balanus

rostratus apertus 84

XIV. Balanus crenatus 84

XV. ( 1, 2) Balanus hoekianus. (3-7) Balanus callistoderma 84

XVI. Acasta spongites japonica 84

XVII. Pachylasma crinoidophilum 84

Food value of sea mussels:

Plate XVIII. (1) The sea mussel (Mytilusedulis Linnaeus). (2) A bed of sea mussels 1 year

old 87

XIX. (1) Interior surface viewof the mantle of a male mussel. (2) Interior surface
view of the mantle of a female mussel. (3) Lateral viewof a mussel with the
shell and mantle of one side removed. (4) Lateral view of afemale mussel
with the shell and mantle of one side and the foot, gills, and abdomen

removed to show the main canals of the genital system 128

XX. Organisms constituting the food of mussels. Diatomaceae 128

XXL Organisms constituting the food of mussels. Diatomaceae 128

XXII. Organisms constituting the food of mussels. Protozoa 128

XXIII. (1) Cross section of the mantle of a female mussel March 3, 1908. (2) Cross

section of the mantle of afemale mussel August 20, 1907. (3) Cross section

of the mantle of a male mussel June 27, 1908. (4) Cross section of the mantle

of a spent female sea mussel August 16, 1908 128

XXIV. (1) A mussel bed at Menemsha Pond, Marthas Vineyard, Mass., exposed

at low tide. (2) Dredging for mussels 128

XXV. (1) A heap of mussel shells, the result of a few days’ work. (2) A heap of
shells from mussels which have been pickled for the New York market. .

128

ILLUSTRATIONS.

Migration or salmon in the Columbia River: Facing page.

Plate XXVI. (i) The two pieces of the marking button, shown separately and riveted

together. (2) Pliers used in attaching marking buttons 134

XXVII. (3) Photograph of eleven marking buttons after they were recovered from
the marked fishes. (4) Photograph of converse faces of the eleven mark-
ing buttons shown in figure 3 142

Natural history of the American lobster:

Plate XXVIII. First larval or surface-swimming stage of the lobster 153

XXIX. Male lobster (Homarus gammarus) with symmetrical claws, and both of

crusher type 276

XXX. (1) Growth stages of lobster eggs and young, to illustrate relative sizes at-
tained at Woods Hole, Mass. (2 and 3) Growth stages of young lobsters,

continued 320

XXXI. Fourth stage of the lobster 340

XXXII. Sixth stage of the lobster 344

XXXIII. Half section of lobster, cut in median plane, to illustrate general anatomy. 408

XXXIV. Transverse section of body of female lobster, in plane of gastric mill 408

XXV. (1) Left eyestalkfrom above, or what was originally the anterior side. (2 and
3) Parts of corneal membrane of compound eye, composed of modified
hexagonal facets of individual eyelets. (4) Left first antenna, from above.

(3 and 6) Left second antenna, from upper and undersides. (7) Left man-
dible, from inner side 408

XXVI. (1) Left first maxilla of adult. (2) Left second maxilla. (3) First maxilli-
ped. (4) Left second maxilliped. (5) Left third maxilliped. (5a and 5b)

Transverse sectional views of three-sided meros and ischium 408

XXVII. (1) Right toothed forceps and cheliped of female lobster, from lower side.

(2) Left cracker claw and cheliped of female from above. (3 and 4) Base

of great cheliped from below 408

XXXVIII. (1-4) Left second to fifth pereiopods or slender legs of adult lobster, from

anterior side 408

XXXIX. (1 and ia) Left first pleopod of female and male, respectively. (2 and 2a)

Left second swimmeretof female and male lobster, respectively. (3) Left
third swimmeret. (4) Left fourth swimmeret from egg-bearing female of
approximately same size as in preceding figure. (5) Left fifth swimmeret
of series 1-3. (6) Left uropod or modified swimmeret of tail fan. (7) The

same appendage reversed 408

XL. Left crusher claw of lobster, partly dissected from upper side, to show rela-
tions of muscles, nerves, blood vessels, and skin, with principal branches

of claw arteries and nerves laid bare 408

XLI. (1) Left second pereiopod, from anterior or upper side. (2) Shell of right

toothed forceps in sectional view from above 408

XLII. (1) Right toothed forceps of lobster in seventh stage. (2) Teeth from dactyl
of lobster in fifth stage. (3) Serrate margin of jaw in area marked a,
figure 1, embracing series i-ii. (4 and 5) Armature of index or propodus
of right toothed forceps of lobster in seventh stage and after molting to the

eighth 408

XLIII. (1) Oblique section through large claw of lobster in first larval stage. (2 and
3) Jaws of cracker claw of lobster weighing about 12 pounds. (4) Profile
of seminal receptacle of female, from molted shell. (5) Skeleton of first
abdominal somite of male, from behind. (6) Seminal receptacle shown in
profile in figure 4, as seen from underside 408

ILLUSTRATIONS.

VII

Natural history of the: American lobster — Continued. Facing page.

Plate XLIV. (i) Immature ovary of lobster with abnormal ring on left anterior lobe for

transmission of left antennal artery. (2) Reproductive organs, from right
side of male. (3) Transverse section of homy pouch of seminal receptacle
of female lobster. (4) Left third swimmeretof female. (5) Lobster’s egg. 408
XLV. (1-5) Diagrams to illustrate structure and growth of ovary of lobster from

first larval stage to maturity 408

XLVI. (1) From transverse section of ovary of lobster 8>J inches long, July 25.

(2) Part of longitudinal section of first larva, at point of attachment of
abductor mandibuli muscle. (3) Part of transverse section of dactyl of
soft lobster, close to spines of dentate margin 408

XLVII. (1) Part of section parallel to long axis of gill. (2) Diagram of transverse
section of lobster’s gill. (3) Transverse section of oviduct of adult lobster

immediately before egg-laying. (4) Transverse section of oviduct of adult

lobster taken immediately after egg-laying 408

Anatomy and physiology of the wing-shell Atrina rigida:

Plate XLVII I . (16) Drawing of specimen to show relative position and appearance of vari-
ous organs 440

XLIX. (17) Drawing of arteries of right side of body and of left mantle lobe, the
shell, right mantle lobe, gills, and kidneyshaving been removed. (18)
Drawing of arteries of left side of body, the shell, left mantle, gills, pos-
terior retractor muscles of the foot, and kidneys having been removed.
(19) Drawing of principal veins of right side of body, the shell, right

mantle lobe, and gills having been removed 440

L. (20) Semidiagrammatic drawing of a specimen, ventral side up, to show

veins which enter kidneys and those which emerge from them 440

TEXT CUTS.

Review of
Fig. 1.

5-
6.

10.

11.

12.

J3-

14.

iS-

16.

i7-

18.

19.

20.

21.

22.

23-

the salmonoid fishes of the Great Lakes:

Cristivomer namaycush siscowet. Siscowet

Leucichthys harengus. Saginaw Bay herring

Leucichthys harengus arcturus, new subspecies

Leucichthys sisco. Cisco of Lake Tippecanoe

Leucichthys sisco huronius. Lake Huron herring

Leucichthys ontariensis, new species

Leucichthys artedi. Lake herring

Leucichthys artedi. Lake herring, female

Leucichthys artedi bisselli. Rawson Lake herring

Leucichthys eriensis. Lake Erie herring, jumbo herring

Leucichthys supemas, new species. Cisco of Lake Superior.

Leucichthys cyanopterus, new species. Bluefin

Leucichthys hoyi. Cisco of Lake Michigan

Leucichthys zenithicus. Lake Superior longjaw

Leucichthys manitoulinus, new species. Manitoulin tullibee

Leucichthys tullibee. Tullibee

Coregonus clupeaformis. Labrador whitefish

Coregonus stanleyi

Leucichthys osmeriformis. Smelt

Coregonus coulteri. Coulter’s whitefish

Coregonus oregonius. Oregon whitefish

Page.

8
8

22
27
29
3°

33
35

VIII

ILLUSTRATIONS.

Barnacles oe Japan and Bering Sea: Page

Fig. i. Scalpellum rubrum 63

2. Scalpellum japonicum 67

3. Scalpellum molliculum 69

4. Heteralepas japonica 71

5. Heteralepas vetula 72

6. Balanus rostratus apertus 74

7. Balanus evermanni 76

8. Balanus hoekianus 77

9. Balanus hoekianus 78

10. Balanus callistoderma 79

11. Pachylasma crinoidophilum 82

Food value of sea mussels:

Fig. 1. Curves showing results of metabolism experiments 104

2. Apparatus for cleaning mussels preparatory to canning or other preservation process. 112
Natural history of the American lobster:

Fig. 1. Giant lobster from New Jersey 197

2. Left second pereiopod of first larva of lobster 226

3. Sectional view of antennal segment to show statocyst 239

4. Locked sliding joint of big claw of lobster 255

5. Locked sliding joint of big claw of crab 256

6 and 7. Great first and small left third claw feet of adult lobster 258

8. Base of right great cheliped of fourth-stage lobster from below 260

9 and 10. Right great cheliped of fourth-stage lobster from above 261

11. Diagram to show serial arrangement of spines in the toothed forceps of lobster 262

12. Projection of serial teeth in segment of big claw of large adult lobster represented in

figure 13 264

13. Large segment of right toothed claw from above, to show periodic teeth 264

14. Left great claw foot of first larva 266

15 and 16. Left and right future toothed and crusher claws of lobster in eighth stage,

seen from above 267

17. Outline of great claw tip 268

18. Outlineof corresponding partof big claw shown in figure 17, but in second larval stage . 268

19. Outline of corresponding part of great claw shown in figures 17 and 18, but at third

larval stage 269

20. Outline of corresponding part of big claw represented in figures 17 to 19, but at fourth

stage 269

21 and 22. Right and left forceps of lobster 24 mm. long, reared in captivity, and ir

months old, in eighth or ninth stage 270

23 and 24. Serrate margins of claws shown in figures 21 and 22 271

25. Armature of right crusher of female lobster 35 mm. long and at approximately tenth

stage 272

26 and 27. Profile and horizontal projection of larger division of right toothed forceps of

male lobster immediately before molt 279

28 and 29. Partial profile, and projection of armature of same claw shown in figures 26

and 27 but immediately after molting 279

30. Diagram to illustrate growth in a single generation of lobster’s eggs during a period of

nearly 3 years, from an initial stage in ovary to time of hatching 296

31. Diagrams of sperm shells of the lobster before, during, and after capsular explosion. . 314

32. Diagrammatic section of sperm cell in capsular explosion 315

33. Outlines to show relative sizes of lobsters’ eggs when laid and when ready to hatch . . 326

34. First larva, or first swimming stage of lobster 329

illustrations.

Natural history or the American lobster — Continued. Page.

Fig. 35. Cephalothorax of lobster in first stage when under stimulus of pressure, drawn im-
mediately after reddening through expansion of chromatophores 330

36. Cephalothorax of the same individual 10 minutes after release from pressure, and

after paling from contraction of chromatophores 330

37, 38, and 39. Parts of seta; from cheliped of larval lobster showing different degrees of

reduction from typical plumose type 333

40. Swimming attitudes of young lobsters in the first free stages 335

41. Second larva, or second swimming stage of lobster 337

42. Third larva, or third swimming stage of lobster 339

Anatomy and physiology of the wing-shell Atrina rjgida:

Fig. 1. The shell 413

2. Diagrammatic cross section of the body anterior to the adductor muscle 415

3. Transverse section of gill 420

4. Diagrammatic drawing of a bit of the gill 421

5. Transverse section of a filament 422

6. Drawing of kidney in position 430

7. Bodies excreted from the kidney 431

8. Section of the glandular portion of the kidney 431

9. Drawing of the digestive system in position 432

10. Drawing of the cerebral and pedal ganglia with their connectives 433

11. Drawing of the visceral ganglia 433

12. Drawing to show distribution of mantle nerves 434

13. Drawing of transverse section of one lobe of otocyst 435

14. Reconstruction of the compound otocyst from a series of sections 435

15. Drawing of transverse section of the foot showing the position of the otocyst 436

A REVIEW OF THE SALMONOID FISHES OF THE GREAT LAKES
WITH NOTES ON THE WHITEFISHES OF OTHER REGIONS

By David Starr Jordan and Barton Warren Evermann

PLATE I

LAKE TROUT; MACKINAW TROUT
Cristivomer namaycush (Walbaum)

A REVIEW OF THE SALMONOID FISHES OF THE GREAT LAKES,
WITH NOTES ON THE WHITEFISHES OF OTHER REGIONS.

J-

By DAVID STARR JORDAN and BARTON WARREN EVERMANN®

In the investigations of the fisheries of the Great Lakes region conducted in 1908
and 1909 by the International Fisheries Commission the writers had opportunity to
examine great numbers of specimens of the food fishes and especially of the Core-
goninae, known as whitefish and lake herring. It has been clearly shown that the fauna
of each of the Great Lakes exhibits peculiarities of its own, and especially that each
lake has one or more species of the group called lake herrings or ciscoes peculiar to itself.
In this paper the species of these and other groups of fresh-water Salmonidse are treated
and figured somewhat fully. The specimens described are in the United States National
Museum, with series of duplicates in the museum of Stanford University. The following
species are described as new:

Leucichthys supernas, Leucichthys cyanopterus, Leucichthys manitoulinus , Leucichthys ontariensis,
. Leucichthys harengus arcturus.

Three others from the same collections have been previously described and figured
(Proc. U. S. Nat. Mus., vol. xxxvi, p. 165-172) by Jordan & Evermann:

Leucichthys huronius, Leucichthys eriensis , Leucichthys zenithicus.

Genus SALVELINUS (Nilsson) Richardson.

Salvelinus fontinalis (Mitchill). Eastern Brook Trout.

The common brook trout occurs in all cold streams and in some lakes throughout this region. It
occurs freely in Lake Superior but not in any other of the Great Lakes. In the streams of Isle Royale
a variety almost jet-black in color is said to occur.

0 In the preparation of this paper the authors have had the assistance of William Francis Thompson, of .Stanford
University. Most of the text figures were drawn by William Sackston Atkinson, and the colored plates are from paintings
made by Charles Bradley Hudson.

48299° — Bull. 29 — II 1

BULLETIN OF THE BUREAU OF FISHERIES.

Genus CRISTIVOMER Gill & Jordan.

Cristivomer namaycush (Walbaum). Lake Trout; Great Lakes Trout; Mackinaw Trout; Togue; Longe;
Namaycush; Siscowet. (PI. i.)

The Great Lakes trout or Mackinaw trout occurs throughout the Great Lakes region, and in the
lakes northwestward to the Yukon and the Arctic Sea. It is subject to many variations in color and
in degree of plumpness, but we find no tangible differences on which the genus can be separated into
species or subspecies.

A notable variant is found in the siscowet ( Salm o siscowet Agassiz, Lake Superior, p. 333, 1850;
Sahno siskawitz Agassiz in Herbert, “Frank Forester’s Fish and Fishing, p. 143, fig. on p. 144, 1849).
This is a pale trout, excessively fat and with the skeleton feeble for its size, found in Lake Superior and
in waters of 50 to 80 fathoms. It is never seen in shallow water. It differs in no technical respect from
the ordinary lake trout, and it is connected with the latter by perfect intergradations known locally as
half-breeds. The siscowet is taken in schools of the deep-water ciscoes, the bluefin ( Leuciclithys cyanop-
terus), the cisco (L. supernas ) and the Lake Superior longjaw (L. zenithicus), themselves also soft-bodied
and very fat. There is every reason to believe that the siscowet is an ordinary trout which has fed

Fig. i. — Cristivomer namaycush sisco-wel. Siscowet. (Drawn from specimen 18 inches long, taken
in Lake Superior off Marquette. Mich.)

on these soft fat fishes and which has followed them into deep water. If so, it should not be regarded
as a distinct species or subspecies.

The siscowet is not badly flavored but too fat to be digestible, and it almost melts away in frying.
Salted, it is more satisfactory, but there is little market for it. Sometimes the walls of the abdomen
are over half an inch in thickness.

Our text figure is taken from a small but very fat example of the typical siscowet taken in a
School of bluefins in about 60 fathoms off Marquette. The colored plate is from a typical lake trout
from Lake Michigan off Berrien County, Mich.

Commercially the lake trout is of great importance. The catch in American waters for the Great
Lakes in 1908, according to the Bureau of the Census, was as follows:

State.

Pounds.

Value.

1 29, 600
6, 798, 000
150, 400
215, 000
4, 710, 100

$9, 640
424, 080
12. 55°
n, 690
34°. 360

12, 003 , 100

798, 320

SALMONOID FISHES OF THE GREAT LAKES.

Genus LEUCICHTHYS Dybowski.

The Lake Herrings.

Argyrosomus Agassiz, Lake Superior, p. 339, 1850 (" clupeijormis” of De Kay, not of Mitehill = harengus) not of
M. de la Pylaie, which, according to Doctor Gill, is P seudoscuzna aquila.

Leucichthys Dybowski, Fische des Baikal-Wassersystemes, Verh. K. K. Zool.-Bot, Gesell. Wien, bd. xxiv, 1874.
p. 390 (Salmo omul Pallas).

Allosomus Jordan, Manual Vertebrates, ed. 2, p. 361, 1878 (Coregonus lullibee Richardson).

Thrissomimus Gill Ms., November. 1909 ( Coregonus artedi Le Sueur).

Cisco Jordan & Evermann, new subgenus (Argyrosomus nigripinnis Gill).

We are indebted to Prof. Theodore Gill for the information that the name Argyrosomus was first
given to the “maigre” of the Mediterranean, and in advance of its use by Agassiz for the genus of
lake herring. The maigre should therefore stand as Argyrosomus aquila instead of Pseudoscicena
aquila. The following statement is given by Professor Gill :

The name Argyrosomus first appears in the “Comptes Rendus du Congr^s Scientifique de France,”
2nd session in 1834, pages524 to 534 (published in 1835). The article is entitled 11 Recherches en France
sur les poissons de l’Oc6an pendant les ann6es 1832 et 1833, par. M. de la Pylaie de Fougbres.”

On page 534, Professor Gill informs us, M. de la Pylaie has the following:

Sous le tribu des Persfeques, nous voyons . . . V Argyrosomus procerus, nouveau genre que j’ai
form6 avec le Scicena aquila Cuv., et auquel j’associe une nouvelle espbce, VArg. sparotdes, de la baie
de Bourg Neuf.

No other reference is made to Argyrosomus or these species. The species Scicena aquila must
be taken as the type of Argyrosomus. The name thus antedates Pseudoscicena Bleeker, given in 1863
to the same species, aquila.

The name Leucichthys, first given by Dybowski in 1874 to two Siberian species of the genus Argy-
rosomus Agassiz, must apparently replace the latter for the lake herring ciscoes with their old world
congeners. Leucichthys, based on Coregonus omul and Coregonus tugun, is separated by Dybowski
from “ Coregonus sensu strictiore” by the terminal mouth. The first species named, Coregonus omul,
may be taken as its type.

Dybowski thus records these species:

2. Gruppe, Leucichthys, Der Mund vorderstandig oder halb oberstandig. Die Symphyse des
Unterkiefers mit einer hockerartigen Anschwellung.

19. Art. Leucichthys omul Pall., 1. c., Taf. vm, Fig. 2. Der Kopf nach vorn zugespitzt, die Schnauze
verlangert. Der Unterkiefer ein wenig vorstehend. Die Nase schwach gewolbt, etc.

20. Art. Leucichthys tugun Pall. Der Kopf nach vorn zugespitzt, die Schnauze wenig verlangert,
der Unterkiefer etwas vorstehend, etc.

In both these species the jaws and tongue are said to be “mit schwacher Zahnehen besetzt.”

Pallas, however, says of L. omul, “ os plane edentulum,” and of L. tugun, “maxilla . . . utraque
edentula.” We find no teeth in the jaws of the American species, and only minute asperities on the
tongue. There is no hook on the end of the lower jaw in any of our species, although a slight promi-
nence in L. johannee, L. prognathus, and L. cyanopterus suggests it. In view of all this there is some
doubt as to whether our American species should be referred to the same genus as Leucichthys omul.
We may note, however, that both Guldenstadt and Pallas deny the presence of teeth in Stenodus leucich-
thys. Our specimens of the latter from the Volga River at Sammara, Russia, show small teeth in both
jaws and on the vomer, palatines, and tongue, as supposed by Doctor Gunther and as shown by the Ameri-
can species, Stenodus mackenzii. The use of Leucichthys as a generic name by Dybowski may indicate
that he had this species, Stenodus leucichthys, in mind as the type of Leucichthys. But he mentions
only the two species omul and tugun. As both of these are said to have teeth, and to have the lower
jaw produced and hooked, it may be that they constitute a separate subgenus, intermediate between
Stenodus on the one hand and the American on the other. To this subgenus the European species
Leucichthys vandesius may possibly belong, as that species is said to have minute teeth on the jaws and
tongue, and a projecting lower jaw and uncurved chin as in Leucichthys omul. On the other hand, the
British species, Leucichthys pollan, much resembles the American species.

bulletin of the bureau of fisheries.

We therefore provisionally adopt the name Leucichthys for the entire group, considering the sub-
genus Leucichthys proper as composed entirely of old world species, and placing the American species
in three subgenera, Thrissomimus, Cisco, and Allosomus .

We further note that in Leucichthys omul 6 to 8 rows of pearly bodies are present in the breeding
season, as in certain species of Coregouus. None of the American species of lake herring shows these
structures, although slight warty elevations are shown in some of our specimens of L. johannce.

This genus Leucichthys includes the species known in America as lake herring, cisco, and tullibee,
and the corresponding forms in northern Europe and northern Asia, known as laksild, sik, vendace,
pollan, etc. These forms are related to the whitefish, Coregouus, agreeing with the latter in the large
silvery scales and obsolescent teeth. In Leucichthys, however, the mouth is larger, with longer jaws,
the lower jaw being at least as long as the upper, and the premaxillaries set nearly horizontally. The
gillrakers are long and slender, about 30 on the lower limb. The jaws are toothless in all of our species.
There are no teeth on the palate but minute teeth are seen on the tongue when dry.

The species are much more active than those of Coregouus and feed more generally on small fishes.
In general, they are less valued as food than the wliitefishes, but at least one of them ranks with the
very best of food fishes. The group separates naturally into three subdivisions which may be called
subgenera.

To the first of these, Thrissomimus (which is the earlier Argyrosomus of Agassiz, the name unfor-
tunately preoccupied), belong the typical lake herring, or laksild, both of Europe and America, fishes with
slender bodies, silvery scales, relatively firm flesh and firm skeleton, and the general form of herring,
to which these fishes bear much external resemblance that indicates no real affinity. All the species
of Thrissomimus have the jaws toothless, which separates them from the Asiatic genus or subgenus
Leucichthys. None of this group or the next one is found in the basin of Lake Winnipeg, which includes
the Lake of the Woods, the Saskatchewan, the Rainy River, and the Red River of the North. The only
species of the genus in this vast basin is the tullibee, Leucichthys tullibee.

To the second group, which we call Cisco, belong the ciscoes, bluefins, blackfins, bloaters, and
longjaws, species living in 50 or more fathoms of water, with the mouth larger than in the lake
herring, and with the skeleton relatively feeble and the flesh softer, often saturated with fat. These
forms are all very closely related and probably sprang from a common stock which is near the species
called L. supernas. It is not clear that they are derived from any of the existing shore species.

To the third group, Allosomus , belong the tullibees, robust, compressed fishes with the tail very
short, the mouth small and the color in general more dusky than silvery. The scales are firm and the
texture of the flesh more solid than in the lake herrings. The species of this group are mostly confined
to the region northwest of Lake Michigan, and they are found mainly in the smaller lakes to the north-
westward of Lake Huron, their distribution being chiefly in the Winnipeg basin. The tullibees are not
greatly valued as food fishes, the flesh being soft and watery and inferior to that of most other Salmonidae.

The Siberian species, Leucichthys peled (Lepechin) (= Salmo cyprinoides Pallas) is doubtless a
tullibee or typical Allosomus.

Besides the species found in the Great Lakes region, we give here an account of all the species of
Leucichthys known from North America. It may be noticed that the species of each group are closely
related to one another, that the differences are more evident in the mass, as in a boat or fish market,
than in individual preserved specimens, that measurements are liable to fluctuation, that individual
differences are unusually great, and finally, that in those characters usually most trustworthy in fishes,
such as the number of scales, fin-rays, gillrakers, etc., the different species are practically in agreement.

ANALYSIS of species of leucichthys found in the great lakes region.

a. Caudal peduncle relatively long and slender, its length along lateral line above last ray of anal more
than .75 length of head, its length from last ray of anal to first of caudal more than its depth;
scales silvery, more or less loosely inserted; body more or less elongate, the depth 3.25 to 5.5 in
length; minute teeth on tongue, none on jaws or palatines.

SALMONOID FISHES OF THE GREAT LAKES.

Thrissomimus:

b. Species of shore waters, spawning in late autumn, the flesh firm, the skeleton well developed, the
mouth small, the maxillary not reaching past middle of eye.

c. Adipose fin very small, usually shorter than eye; body elongate, the caudal peduncle slender,
its least depth about 3 in head; body slender, the depth 4.33 to 4.66 in length; body anteri-
orly long, the pectoral not reaching nearly halfway to ventrals; back lustrous bluish in life,

usually not marked with lengthwise streaks harengus; osmeriformis

cc. Adipose fin well developed, longer than eye.

d. Body elongate, the depth 4.33 to 4.5 in length; caudal peduncle slender, its least depth about
3 in head; body anteriorly long, the pectoral not reaching halfway to ventrals in the
adult; back dark lustrous blue in life, usually marked with dark lengthwise streaks.

e. Body subcylindrical, little compressed, its depth about 4.5 in length, its greatest depth

usually before dorsal sisco; huronius

ee. Body more robust and more compressed, its depth about 4 in length, the greatest depth
usually near insertion of dorsal .... ontariensis; lucidus; laurettce; alascanus; pusillus
dd. Body deep and compressed, the depth 3.33 to about 4 in length; caudal peduncle stout, its
least depth nearly half head; pectoral reaching more than halfway to ventrals; adipose
fin larger, longer than eye; back olive-gray, without distinct dark streaks.

/. Body moderately robust, depth 3.5 to 4 in length; angle at the nape slight, scales rela-
tively thin and loosely attached artedi; bisselli

//. Body very robust, depth 3.33 to 3.5 in length, with a strong angle at the nape; scales
large, regular, and firmly attached; flesh rich, of excellent flavor eriensis

Cisco:

bb. Deep-water forms found in 50 fathoms and upward, spawning in midsummer, the flesh soft and
fat, the skeleton relatively feeble, the mouth relatively large; adipose fin rather large.

g. Mouth moderate, the maxillary not extending to middle of eye; premaxillary nearly
horizontal, the upper jaw not truncate; head broad, the width between temples
rather more than half length of top of head; caudal peduncle stout.

h. Lower jaw distinctly projecting, its tip somewhat produced upward; head thick;
eye large; pectoral extending more than halfway to ventrals; depth about 4 in
length; adipose fin small; fins with little dark.

i. Head short and slender, 4.66 in length; mouth relatively small; adipose fin rather

small supernas

ii. Plead long and thick, 4 to 4.25 in length; mouth large; adipose fin small.

j. Gillrakers more than 40 prognathus

jj. Gillrakers fewer than 40 johannce

hh. Lower jaw included; head long, about 4.5 in length; body moderate, the depth
about 4.2 in length; caudal peduncle thick; fins all broadly edged with black.

k. Gillrakers 16 to 19+31 to 35 nigripinnis

kk. Fins slightly bluish or dusky at tip; gillrakers 14+25 cyanopterus

gg. Mouth larger, the maxillary extending about to middle of eye; snout long, sub-
truncate at tip, the premaxillaries more or less vertically placed, lower jaw included;
body slender, the depth more than 4 times in length; caudal peduncle slender;
head slender, its breadth at temples half its length above. Color pale, often some
dark on fins except the ventrals.

I. Pectoral not reaching halfway to base of ventrals; snout about equal to eye,

about 4 in head; depth of tail much greater than snout; snout more
truncate than in next species; scales about 70; color very silvery. . . . hoyi

II. Pectoral reaching more than halfwaj' to base of ventrals; depth 4.6 to 4.66

in length; snout less truncate than in L. hoyi, 3 to 3.5 in head, longer
than eye; depth of tail not equal to snout; scales about 77. Color
brassy -silvery, with dark points on all fins save ventrals zenithicus

BULLETIN of the bureau of fisheries.

Allosomus:

on. Caudal peduncle short and thick, its length along lateral line above last ray of anal about
half head, its length from last ray of anal to first of caudal less than its depth; skeleton and
flesh firm; scales dusky, firmly inserted; body deep, compressed, the depth 2.25 to 3.4 in
length; no teeth. Colors dark, back and fins dusky.

m. Depth 3.2 to 3.33 in length; adipose fin very small, shorter than eye;

caudal peduncle moderate, its depth 2.5 in head manitoulinus

mm. Depth 2.5 to 3 in length; adipose fin large, longer than eye; body
short and deep; caudal .peduncle very short and deep, its depth 2

to 2.25 in head tullibee

The relationships of the species may be indicated graphically as follows:

lucidus

arcturus /

harengus

manitoulinus tullibee

osmeriformis

supernas

ho^'i

zenithicus

liuronius sisco

ontariensis

prognathus cyanopterus

artedi bisselli

johannae nigripinnis enensis.

Subgenus THRISSOMIMUS Gill.

Leucichthys harengus (Richardson). Saginaw Bay Herring; Georgian Bay Herring.

Salmo ( Coregonus ) harengus Richardson. Fauna Boreali-Americana, hi. p. 210, pi. xc, fig. 2. 1836, Georgian
Bay at Penetanguishene, Ontario.

Coregonus clupeiformis, Agassiz, Lake Superior, p. 339, 1850, the Pic (Michipicoten Island); not of Mitchill.
Coregonus albus, Agassiz, op. cit., p. 342, the Pic; not of Le Sueur.

Argyrosomus artedi, Evermann & Smith, Rept. U. S. Fish Comm. 1894, p. 305, pi. 21, in part, Bayfield, Wis.

Distribution : Bays and shallow waters of Lake Huron and Lake Michigan ; Georgian Bay, Saginaw
Bay, Green Bay, etc.

The herring of Georgian Bay, hitherto confounded with Leucichthys artedi, is a distinct species, well
separated from all the other species of this group found in the Great Lakes by the very small adipose
fin, length of which is about 5 in head. This character is well shown in Richardson’s figure of the species.
In form the Georgian Bay herring is much more slender than L. artedi, approaching in that regard
the herring of Lake Huron ( Leucichthys sisco huronius). As a food fish Leucichthys harengus is distinctly
superior to either L. artedi or L. sisco huronius, though by no means equal to A. eriensis.

Doctor Richardson’s specimens came from Penetanguishene at the southern end of Georgian Bay.
We obtained many specimens from the neighboring port of Collingwood, one of which we have figured,
and which is the type of the following description. This may be regarded as typical of Leucichthys
harengus. We have seen specimens from near Mackinac which seem to belong to this species.

The herring of Saginaw Bay is also in all respects identical with the specimens from Collingwood.
It is not only slender, as usual in this species, but reaches only a small size, the average weight when
mature being 6 ounces, those examined by us, from Bayport, ranging from 2.5 to 9.5 ounces. The
maximum length is 12 inches and the usual from 9 to 10.

A small copepod which Dr. Charles B. Wilson is describing as a new species of Lernseopoda is
parasitic on the gills of the Saginaw Bay herring.

SALMONOID FISHES OF THE GREAT LAKES.

Of all the species of Leucichthys this must be the most numerous in individuals, occupying as it
does most of the open waters of Lake Huron and Lake Michigan. It is taken in great abundance in
Saginaw Bay, where it is largely salted for commercial purposes. It is the most important fish in the
fisheries of Saginaw Bay, the catch in 1908 amounting to 3,871,345 pounds, while the total catch of all
species was 7,104,703 pounds.

This species is said to range down the shores of Lake Huron to Port Huron, and to be taken occa-
sionally in Lake Erie, having come down the Detroit River. It is also said that the shore lake herring
of Green Bay in Lake Michigan are of the same type. These Saginaw herring differ from the ordinary
blueback of Lake Huron and Lake Michigan in their gray color, less cylindrical body, smaller size, and
especially in the much smaller adipose fin.

Specimens from near Pine, Ind., at the southern end of Lake Michigan, seem to belong to this
species rather than to Leucichthys sisco huronius. These are small in size, gray in color, and with the
adipose fin not larger than in L. harengus.

Head 4.33 in body without caudal; depth 4.33; length of caudal peduncle measured from last anal
ray to first of caudal, 2.12 in head; depth 3; eye 4; snout 3.75; interorbital space 3.75; maxillary meas-
ured from tip of snout 3; dorsal 11, anal 12; scales 10-83-9, between occiput and dorsal, 33; branchi-
ostegals 9; gillrakers 16+31, length 0.87 eye diameter.

Body elongate, not much compressed, more cylindrical than in most species. Width 1.75 in its depth, •
more convex ventrally; caudal peduncle long, terete, not deep nor much compressed; back above occiput

Fig. 2. — Leucichthys harengus (Richardson). Saginaw Bay herring. (Drawn from a specimen 1 1
inches long, collected in Georgian Bay, Lake Huron, Collingwood, Ontario.)

only moderately arched; head small; under jaw projecting somewhat; maxillary not quite extending
below the anterior edge of pupil, thrice as long as broad; teeth on tongue only, very minute and few
in number; distance from snout to occiput always less than half distance from occiput to dorsal
insertion; dorsal inserted midway between snout and base of caudal, somewhat small, its longest ray
1.75 in head, its base about half length of head, usually shorter than eye, rarely longer; adipose small,
its length from insertion to tip 5 in head, low, its height 0.33 its length, but variable in different speci-
mens; in general its greatest length is 4 to 4.5 times in the distance from the depressed tip of the dorsal
to its base; ventrals somewhat shorter than pectoral, the latter about 0.66 length of head; anal small, its
base equal to that of dorsal, its longest ray 2.33 in head; lateral line straight; scales moderate in size.

Color in spirits, dark along the center of the back and on the dorsal surface of the head, coffee-colored
on the remainder, silvery laterally and colorless ventrally; dorsal black on distal half; caudal dark,
edged with black ; pectoral and ventral lightly touched w'ith dark along first rays ; anal dark on distal half.

Specimens from Blind River on the North Channel of Lake Huron differ from the Collingwood
specimens in having the colors darker, the surface suffused by dusky, as usual in “muskeeg” waters, or
water darkened by drainage from sphagnum swamps. These are also more slender and smaller, but
do not differ otherwise. A figure of one is presented.

The ordinary herring of Lake Superior are placed provisionally under Leucichthys harengus, of which
they constitute a tangible variety or subspecies, distinguished by the larger size, the more cylindrical

bulletin of the bureau of fisheries.

form, and in general by the still smaller adipose fin. But these characters are average only, and are
subject to much variation, hence we refrain from regarding the Lake Superior herring as a distinct
species. Specimens having these characters were taken at Sault Ste. Marie, both above the Rapids
(Point aux Pins) and below (St. Marys River). Specimens exactly similar were secured from Peter
Anderson, a fisherman at Marquette. These are rather larger than the specimens from Collingwood,
but exactly like them in form and color. The figure of Evermann & Smith taken from a specimen
from Bayfield, Wis., seems to be the same, although named Argyrosomus artedi in their plate.

Fig. 3. — Leucichthys harengus (Richardson). Saginaw Bay herring. (Drawn from a young exam-
ple, 9 inches long, collected in Blind River, North Channel, Lake Huron.)

In the work of the International Fisheries Commission it was claimed by the fishermen about Duluth
that a mesh of less than 2.5 inches was necessary for the capture of the lake herring. The fishermen
about Marquette were entirely satisfied with this mesh. It was claimed at Duluth that the herring
there were more slender than those to the eastward of Keweenaw Point. Examination of specimens
shows this to be true. The lake herring examined from Duluth, Knife River, Port Arthur, and all
points on the northwest shore of Lake Superior, are more slender, less compressed, and more spindle-
shaped than those from Georgian Bay and Marquette. On a single specimen no great difference is
shown, but in a boat load of herring it is notable. Possibly the difference is due to scantier food on

Fig. 4. — Leucichthys harengus arclurus Jordan & Evermann, new subspecies. (Drawn from
the type, a specimen 1 1.5 inches long, collected in Knife River, Lake Superior, near Duluth.)

the narrow rocky shelf inhabited by these fishes along the north shore. Possibly it has a certain taxo-
nomic value. The lake herring is a shore fish, and the great depth of the waters of Lake Superior more
or less completely isolates the fishes of Isle Royale and neighboring shores from those of the eastern
and southern part of the lake.

We present a figure of a specimen from Knife River, near Duluth, typical of the subspecies which
we call Leucichthys harengus arcturus. This form agrees exactly with the ordinary harengus of Geor-
gian Bay in the small size of the adipose fin. The fishes from Michipicoten Island (“ the Pic ”) in Lake
Superior, called by Agassiz Coregonus albus, may belong to this slender type.

SALMONOID FISHES OF THE GREAT LAKES.

Comparison oj specimens of Leucichthys harengus.

Lake Huron.
L. harengus.

Lake Superior.

L. harengus arciurus.

Lake Michigan.
L. harengus.

Colling-

wood.

Blind

River.

Mar-

quette.

Knife

River.

Duluth.

Pine,

Ind.

Specimen no. .

5267

5283

5271

s=s6

5210

5288

5290

Length without caudal mm. .

243

215

255

253

238

215

245

Dorsal rays

1 1

I I

Anal rays

1 1

1 2

Scales

Scales between occiput and dorsal

10-83-9

9-85-9

9-80-8

10-79-8

9-86-8

9-90-8

9-80-8

fins

Branchiostegals

Gillrakers

Comparative measurements: ®

16 +31

16 +29

16 +30

16 +3°

16 +30

18+35

17+31

Head

0. 23

0. 22

0. 225

0. 23

0. 22

0. 23

O. 235

Depth of body

Caudal peduncle, length from anal

• 23

. 20

. 21

. 22

. 20

. 21

• 205

to point of caudal rays

. 10

. 12

. 1 1

• 103

Caudal peduncle, depth (least) ....

• 075

. 07

• 07

. 07

Eye

• 055

• 05

•05

• 05

Snout from eye

■ 055

• 05

. 06

• 05

• 055

. 06

Interorbital space

. 065

. 06

. 065

. 06

• 065

Maxillary length from tip of snout .

• 075

. 07

.08

• 075

. 07

• 075

Snout to occiput

. 16

• IS

. 16

• 15 5

• 15

• 155

. l6

Ventrals to pectorals

Pectoral length in ventral-pectoral

• 35

.31

• 32

• 325

■ 31

distance

2.25

2. 20

2. 125

2. 25

2 . 00

2 . OO

Pectoral length

. 16

. 14

• 15

. 14

• 155

. l6

Ventral length

• 14

• 13

• 14

. 14

• 15

Dorsal height

. 14

. 12

• 135

. 14

• 15

Adipose length

• 05

. 04

• 055

. 06

• 05

• 05s

Anal height

• 09

. 085

.09

.08

. 09

• 09

a Measurements in hundredths of body lengths unless otherwise specified.

Leucichthys osmeriformis (Smith). Seneca Lake Herring; Seneca Lake Smelt.

Coregonus osmeriformis Smith, Bull. U. S. Fish. Comm., vol. xiv, 1894, pi. 1, 2, Seneca Lake; Skaneateles Lake.

Evermann & Smith, Rept. U. S. Fish Comm. 1894, p. 305, 1896; same specimens.

Distribution: Lakes of central New York, tributary to Lake Ontario.

We have examined the type (from Seneca Lake, New York) and the 4 cotypes (from Skaneateles
Lake, New York) of this species, which is locally known as smelt. It is one of the smallest species and
is allied to Leucichthys harengus, with which it agrees in the slender body and very small adipose fin.
It differs from that species, however, in the considerably longer maxillary, longer and decidedly project-
ing lower jaw, larger eye, and longer head.

The following is the substance of the account given by Doctor Smith, whose figure we copy (fig.
21, p. 40):

Head 3.9; depth 5; eye 3.9; dorsal 9; anal 13; scales 9-83-10; maxillary 2.6. Body elongate,
slender, back not elevated; head rather large, its width equal to half its length; length of top of head
2.25 in distance from occiput to dorsal, greatest depth considerably less than length of head; eye
large, equal to snout; gillrakers very long and slender, as long as eye, 20+35; dorsal fin rather high, its
height equal to 0.8 depth of body and 1.5 times length of base of fin, its origin nearer base of caudal
than snout, its free margin nearly vertical, straight; longest anal ray 0.8 length of base of fin ; ventral long,
equal to height of dorsal, its length equal to 0.75 of distance from ventral origin to vent; ventral origin
midway between base of caudal and pupil; adipose dorsal very small, described as long and slender, of
same width throughout, its width 0.33 its length. Mouth large, the lower jaw projecting, the snout
straight; maxillary 3 in length of head, its posterior edge extending to line drawn vertically through
anterior margin of pupil; mandible 0.5 length of head, its angle under the pupil; teeth present on the
tongue. Color above grayish silvery; sides bright silvery; below white; tips of dorsal and caudal dark.
Length 10 inches. Known from Seneca and Skaneateles lakes, but probably occurring in other deep
lakes of central New York.

BULLETIN OF THE BUREAU OF FISHERIES.

Leucichthys sisco (Jordan). Cisco of Lake Tippecanoe.

Argyrosomus sisco Jordan, Amer. Nat. 1875, p. 135, Lake Tippecanoe at Warsaw, Ind.; collector, J. H. Carpenter:
Rept. Geol. Survey Indiana, 1876, p. 4, with a crude figure, Lake Tippecanoe, Lake Geneva.

Argyrosomus artedi sisco, Jordan & Evermann, Eishes North and Mid. Amer., pt. 1, 1898, p. 469, and elsewhere.

Habitat: Small glacial lakes of northern Indiana and southern Wisconsin formerly tributary to
Lake Michigan (lakes Tippecanoe, Barber, Shriner, James, Oconomowoc, Green, La Belle, etc.).

Comparison of the Lake Michigan herring with the “sisco” of Lake Tippecanoe convinces us that
no specific difference can be made out by which the two can be separated.

The cisco of Lake Tippecanoe is merely a landlocked form of the ordinary Michigan herring, smaller,
softer in flesh, and more plump, but showing no technical differences whatever. This was the judgment
of Jordan & Evermann in 1898, but we then made the mistake of supposing the Lake Michigan species
to be the true artedi. If the common Michigan herring is to receive a distinctive name, it may be pro-
visionally called Leucichthys sisco huronius. As a matter of fact, however, sisco is the variety and
in strictness each separate lake has its own variety of “cisco,” as such changes as the form has under-
gone since post glacial times must have taken place separately in each of the several lakes in which the

Fig. 5. — Leucichtkys sisco ( Jordan). Cisco of Lake Tippecanoe. (Drawn from specimen 9 inches
long, collected in Lake Geneva, Wisconsin.)

cisco is left. As a whole this species differs little from L. harengus except in the larger adipose fin,
which is, however, subject to considerable variations. In general it is longer than the eye and is con-
tained 3.5 times in the distance from the depressed tip of the dorsal to its base. On the whole harengus
is the more slender fish and paler in color. Ultimately ontariensis and sisco, with possibly the deep
water supernas, may be regarded as subspecies of harengus.

The name Argyrosomus sisco was applied in 1875 to the cisco of Lake Tippecanoe, a small lake
herring, inhabiting the depths of the glacial lakes in northern Indiana and southern Wisconsin, formerly
tributary to Lake Michigan. These fishes are known to occur in lakes Tippecanoe, Barber, Crooked,
Shriner, Twin, Cedar and James in northern Indiana, and in lakes Geneva, Oconomowoc, and La Belle
in Wisconsin. If these are relics of an earlier fauna, as is probable, the cisco in Indiana and the
cisco of Wisconsin must have been separately derived from a common ancestor of which huronius is
the direct descendant, and from which neither has obviously changed. The name sisco applied to
the first species of fish described by the present senior writer is much older than that of huronius,
and as elsewhere stated, the common lake form must stand as the subspecies if the two are separated.
We do not know the origin of the word “cisco” nor do we know whether it is related to “siscowet.”
We now adopt the current spelling of “cisco” instead of “sisco,” the form under which the cisco of
Lake Tippecanoe first became known to us. The following is the substance of the original description
of the type of A. sisco from Lake Tippecanoe:

Head 4.33 to 5 in length; depth 4.1 (4 to 4.25); eye 3.6 in head; maxillaries 3.33 in head, not
reaching center of eye; length of mandible 2.125 in head, much more than least depth of tail; scales
84; dorsal 9 or 10; pectoral 15; ventral 12; anal 12. Form regular, spindle-shaped, slightly elevated
at beginning of the dorsal, the form essentially as in the common Lake Michigan herring. Lower jaw
the longer; distance from occiput to snout 2.33 in distance from occiput to dorsal; depth at occiput

SALMONOID FISHES OF THE GREAT LAKES.

1.5 in length of head. Scales thin but firm. Dorsal short, rather high, its height 1.5 in head, the
longest ray 3 times the shortest; adipose fin “rather slender,” reaching slightly beyond anal; pectoral
long and pointed, not reaching nearly to ventrals; ventrals more than 0.66 length of head, falling much
short of vent, the accessory scale short and triangular, not half length of fin; depth at vent 5.75 in
body; caudal deeply forked; vent to base of caudal below, 4.6 times in length.

Color, deep steel blue, becoming gradually paler below to lateral line, where it changes to silvery;
scales above dotted with black, with traces of lines along rows of scales; vertical fins and tips of paired
fins also thickly punctate; dark dots on skin of head. Length 9.5 inches. Said occasionally to reach
a weight of 1.5 to 2 pounds.

A single specimen from Lake Geneva was described a.t the same time as more slender; the depth
5, the head 4.66 in length, and the eye 4 in head; maxillary 2.87 in head, the depth at the vent 6.75 in
length, the distance from the vent to base of caudal below 4 times in length. Scales 77.

The following account was given of the habits of the fish in Lake Tippecanoe by Judge Carpenter:

Some years ago, probably five, these fish were discovered on the north side of Tippecanoe Lake
by Isaac Johnson, and at each return of their spawning season, which is the last of November, they
have reappeared in large numbers. They are not seen at any other season of the year, keeping them-
selves in the deep water of the lakes. The general opinion is that they will not bite at a hook, but Mr.
Johnson says that he has on one or two occasions caught them with a hook. To my knowledge they
have never been found in but two of our lakes, Tippecanoe and Barber, which are both large lakes and
close together, as will be seen by reference to the map.

The spawning season lasts about two weeks and they come in myriads into the streams which
enter the lakes. There are large numbers of persons who are engaged night and day taking them with
small dip nets. They are caught in quantities that would surprise you, could you witness it. Those
who live in the neighborhood put up large quantities of them, they being the only fish caught in the
lakes that will bear salting. Some gentlemen who have been fishing to-day (Dec. 8) inform me that
the run is abating and that in a few days the fishes will have taken their departure for the deep water
of the lakes and will be seen no more until next November.

We here present a description of a specimen in the U. S. National Museum, from Lake Geneva,
with a figure taken from the same fish. It will be noticed that the differences already noted between
Wisconsin and Indiana specimens do not hold in this case, and the same specific name must suffice for
both. In the specimen before us the ventral seems to be placed farther forward than in the Michigan
herring. This appearance is doubtless fallacious, due to the flabbiness of the fish after spawning and
the now rather soft condition of the specimen. In life it would doubtless appear more elongate.

Specimen from Lake Geneva, Wisconsin Body length without caudal, 8 inches; head 4.33 in body;
depth 4.33; length of caudal peduncle 2 in head, its depth 3.33; eye 4 in head; snout 4; interorbital
space 3.66; maxillary measured from tip of snout 4; width of opercle 4 in head, subopercle 6.5; dorsal
10; anal 12; scales 8-80-8, between occiput and dorsal 36; branchiostegals 10; gillrakers 18+32.

Body elongate; dorsal and ventral outlines similar, nearly parallel in central third of body; caudal
peduncle slender, long, little compressed; head moderate in size, pointed; dorsal outline straight;
lower jaw longer than upper; maxillary extending under anterior edge of pupil; teeth on tongue only,
very small and few; distance from snout to occiput more than twice in distance from occiput to dorsal.

Scales thin, rather small, not varying much in size between anterior and posterior; lateral line
straight, nearest to dorsal contour.

Dorsal inserted slightly nearer cdudal than tip of snout, its ray 1.66 in head (specimen mutilated,
probably slightly longer); adipose from insertion to tip contained 4 in head, its height 10; anal trun-
cate, its longest ray 2.75 in head; ventral insertion below first rays of dorsal; length 1.66 in head, its
scale 2.33 in ventral length; pectoral short, 2.33 in distance between pectoral and ventral bases;
caudal deeply forked.

Color in spirits light, darker above, silvery on sides from slightly above lateral line, colorless ven-
trally; all fins colorless (as far as can be seen in the poor state of specimen).

We have also received three fine specimens of the Indiana cisco, from Lake James, Steuben County,
Ind., through the courtesy of Willis S. Blatchley, state geologist of Indiana. These specimens agree
with the preceding accounts and we are quite unable to see that they differ in any regard whatever from
examples of huronius from Port Huron. The adipose fin varies somewhat, but in all it is a little

BULLETIN OF THE BUREAU OF FISHERIES.

longer than eye, and 3.5 times in the distance from the depressed dorsal to its base. The gillrakers are
16 to 18 + 31 or 32. The eye, as in huronius, is smaller than in the original sisco from Lake Tippecanoe.

It is astonishing how long the slight characteristics of the Lake Michigan and Lake Huron herring
{huronius) persist in these separated waifs of the glacial lakes, once part of this lake system.

Leucichthys sisco huronius (Jordan & Evermann). Lake Huron Herring. (PI. 11.)

Argyrosomus huronius Jordan & Evermann, Proc. U. S. Nat. Mus., xxxvi, p. 167, fig. 2, March 3, 1909, Port
Stanley, Ontario.

This is the common bluebaek or Michigan herring of Lake Huron and Lake Michigan. It occa-
sionally enters Lake Erie, where it is recognized as the Lake Huron herring. We found no specimens
in Lake Superior, but have recently received 4 from Wiarton, on Georgian Bay, through the kindness
of the Doyle Fish Company, of Toronto. The original type of huronius figured by Jordan & Evermann
was obtained at Port Stanley, on the north shore of Lake Erie, where about a dozen of this species were
found mixed with about a thousand of Leucichthys eriensis. We have also specimens obtained at Erie,
Pa., by Dr. Seth E. Meek, and numerous young examples from Lake Michigan. We are not able to
see that these differ from Lake Huron specimens. Numerous specimens were taken at Port Huron
and Mackinac. These vary considerably in the number of scales (80 to 90), but the form and general
coloration of lustrous blue is seen in all examples. In all, the adipose fin is large, and the space
between pectoral and ventral more than twice length of pectoral. The caudal peduncle is almost as

Fig. 6. — Leucichthys sisco huronius (Jordan & Evermann). Lake Huron Herring. From the type.

slender as in harengus. We may note that but a single specimen of artedi as accurately determined
has been seen by us from Lake Huron.

The Lake Huron herring may be described as follows' Head 4.66 in length to base of caudal; depth
4.25; length of caudal peduncle from anal to first caudal rays 2 in head; depth of caudal peduncle 2.9;
eye 5; snout 4; interorbital space 3.33; length of maxillary from tip of snout 3; dorsal 10 or 11; anal
11 or 12; scales in lateral line 75 to 85; between lateral line and origin of dorsal 8; between occiput and
dorsal 36; gillrakers 14 to 16+29 1:0 31-

Body notably elongate, elliptical, with slender, pointed head and slender tail, less compressed than
in the other species of the genus; head small, the snout long and pointed, distance from tip of snout
to posterior edge of orbit equaling 0.5 length of head;0 lower jaw not closing within the upper, but
extending slightly beyond it; maxillary reaching a pcint below center of pupil, its width contained 3
times in the length; teeth on tongue only, minute, seen only by drying; gillrakers on first arch very
slender, those near angle equal in length to diameter of eye, lateral line almost straight; scales large
and rather loosely attached; dorsal inserted midway between anterior border of eye and base of
caudal; height of first ray contained about 1.6 times in length of head; adipose fin large, longer
than eye; length of base about equal to its height; origin of ventrals below middle of dorsal, the rays
slightly shorter than those of dorsal; length of first anal ray 2.5 in head; caudal deeply forked; pectoral
short, about 1.5 in head.

a Our drawing is not accurate as to this character.

SALMONOID FISHES OF THE GREAT LAKES.

Color in life, clear metallic blue above, silvery below; in spirits, silvery, dusky above, light below;
a very indistinct, narrow, dusky stripe along each row of scales on upper half of body; dorsal with a
broad dusky margin; caudal largely dusky ; a mere trace of dark color on paired fins and the anal.

The type, no. 62516, U. S. National Museum, a female, measures 14.75 inches in length and was
taken at Port Stanley, Ontario, by the writers, on July 29, 1908. A cotype, no. 13082, Stanford Uni-
versity collection, measuring 17 inches long, has 10 rays in the dorsal and a slightly longer pectoral.

The flesh of this species is rather dry and flavorless, something like that of the Menominee white-
fish, Coregonus quad rilat era lis, and it is not to be compared as a food fish with the Erie herring.

Comparison of specimens of Leucichthys sisco huronius.

Erie. Pa.

Port Huron.

Specimen no. .

493 2

4912

5226

5222

5224

Length without caudal mm. .

310

290

325

220

Dorsal rays (fully developed)

1 1

Anal rays

1 1

1 2

Scales

8-84-7

8-85-7

8-75-7

8-82-7

8-82-8

Scales between occiput and dorsal fin

Branchiostegals

Gillrakers

16 +3 1

16 +31

14 +29

14+29

16 +31

1. 8

1.8

Comparative measurements: a

Head

0. 21

0. 22

O. 23

Depth

. 24

■ 24

. 21

. 22

Caudal peduncle, length from anal to first caudal

rays

. 10

. 1 1

. 1 2

• 125

. 1 1

Caudal peduncle, depth

• 07

.07

• 075

• 07

. 07

Eye

■ 045

. 04

• 045

. 04

• 055

Snout

• 05

• 055

. 06

Interorbital space

. 065

. 06

. 06s

. 06

. 065

Maxillary length from tip of snout

• 07s

• 075

. 07

Snout to occiput

■ 14

• 15

. 16

Ventrals to pectorals

• 35

• 34

. 28

•33

Pectorals in pectoral-ventral distance

2. 50

2. 33

2. 20

2. 00

2. 20

Pectoral length

■ 14

• 14

• 15

Ventral length

. 14

• 14

. 14

• 14

Dorsal height

. 125

• 13

• 14

• 135

• 14

Adipose length.

. 065

. 06

. 065

Anal height

. 08

• 09

• 095

. 08

a Measurements in hundredths of body length unless otherwise specified.

Leucichthys ontariensis Jordan & Evermann, new species.

Coregonus clupeiformis, De Kay, New York Fauna, Fishes, p. 248, pi. 60, fig. 198. 1842, Lake Ontario; not of
Mitchill.

Habitat: Lake Ontario and Cayuga Lake, New York.

The ordinary lake herring of Lake Ontario is allied to Leucichthys artedi, but is more elongate, the
caudal peduncle more slender, the pectoral not reaching nearly halfway to ventrals and the color
much darker, the back, as in leucichthys sisco huronius, being lustrous blue. In all these regards the
form stands intermediate between L. sisco and L. artedi, though doubtless nearer the former, toward
which it seems to vary. The adipose fin, as in huronius and artedi, is large. From huronius it differs
in being more compressed and stouter in every part.

The specimens before us, five in number, were taken by Dr. Seth E. Meek at Deseronto, Ontario,
the Bay of Quinte. The type is no. 64673, U. S. National Museum (collector’s number 29-2). This
description is based on the type and four other specimens from Deseronto.

Head 4.5 in body without caudal; depth about 4 (3.75 to 4.25); length of caudal peduncle from
last rays of anal to first of caudal 2.5 in head, depth 2.66; eye 4.75 in head; snout 4; interorbital space
3.75; maxillary, measured from tip of snout, 3; width of opercle 3.66 in head, subopercle 6.75; dorsal
10; anal 11 ; scales 9-76-8, between occiput and dorsal 35 ; branchiostegals 9 ; gillrakers 14+27.

Body elongate, more so than in Leucichthys artedi; dorsal and ventral outlines similar, convex;
body compressed, width 2.12 in depth; depth varying in other specimens to 4 in body length, in which
case the width is 1.75 to 2 in depth; caudal peduncle not greatly compressed, longer than deep; head

bulletin of the bureau of fisheries.

pointed, lower jaw slightly projecting, not usually included in the upper; maxillary extending to below
anterior edge of pupil, its width 3 in its length, supplementary bone 3 in its length. Very minute
teeth on tongue, none elsewhere. Scales moderate, not firmly attached, nearly equal in size posteriorly
above anal, but not quite to those above tip of pectoral; lateral line nearly straight. Dorsal inserted
midway between snout and caudal, its longest ray 1.66 in head; adipose fin moderate, measured from
insertion to tip 4 in head, its height 9; anal concave, its longest ray 2.5 in head; ventral length 1.62 in
head, its scale 2.5 in ventral length; pectoral short, reaching less than halfwray to insertion of ventrals,
its length 2.33 in distance between pectoral and ventrals.

Color in spirits dark; a dark blue shading under the scales dorsally, silvery laterally and colorless
ventrally; dorsal darkened on distal end; caudal dark, edged with darker, anal, ventrals, and pectorals
nearly clear.

Fig. 7. — Leucichthys ontariensis Jordan & Evermann, new species. (Drawn from a specimen 13
inches long, collected in Lake Ontario off Deseronto. Ontario.)

This species is intermediate between sisco and artedi , differing from the latter chiefly in the greater
elongation of the body and the relatively shorter pectoral fin. It is claimed by fishermen that a mesh
of 2^4 inches is required for these fishes, w'hile 3^ is adequate for the capture of artedi or eriensis.

Reed & Wright a say that this fish, which they identified as L. osmeriformis, is taken in Cayuga
Lake in fairly large numbers, but that it is not as common as formerly. They were informed by old
fishermen that it has never been abundant since the introduction of the alewife, which occurred about
1872, or earlier.

Comparison oj specimens oj Leucichthys ontariensis from Deseronto.

Length without caudal

Dorsal rays

Anal rays

Scales

Scales between occiput and dorsal fin

Branchiostegals

Gillrakers

Comparative measurements:^

Head

Depth

Caudal peduncle, length from anal to first of caudal

Caudal peduncle, depth

Eye

Snout from eye '.

Interorbital space

Maxillary length from tip of snout

Snout to occiput

Ventrals to pectorals

Pectoral length in pectoral-ventral distance

Pectoral length

Ventral length

Dorsal height

Adipose length

Anal height

Specimen no .
mm.

495

492

4918

300

310

1 1

9-76-8

8-72-7

9-77-7

10-8

14+27

16 + 29

0. 22

0.21

0. 22

. 28

. 24

. 28

. 095

. 11

. 09

.08

. 09

• 05

- 05

. 06

• 05

. 06

■ 075

. 07

- 07

. 15

. IS

- 15

• 34

- 37

2-33

2.33

2. 66

. 14

• is

- 15

• 14

• 15

- 15

. 1 4

. 14

• 15

• 055

. 065

. 06

.08

. 08s

. 10

a The vertebrates of the Cayuga Lake basin, New York, by Hugh D. Reed& Albert H. Wright, Proceedings American
Philosophical Society, vol. xlviii, no. 193, 1909, p. 398.

& Measurements in hundredths of body length unless otherwise specified.

SALMONIOD FISHES OF THE GREAT LAKES.

Leucichthys lucidus (Richardson). Great Bear Lake Herrinq.

Salmo ( Coregonus ) lucidus Richardson, Fauna Bor.-Amer., vol. in, p. 207, pi. xc, fig. 1, 1836, with figure. Great
Bear Lake.

Coregonus lucidus, Gunther, Cat., vol. vi, p. 198, 1866, Great Bear Lake. Gilbert, Bull. U. S. Fish. Comm., vol.
xiv, 1894, p. 24, Great Bear Lake.

Argyrosomus lucidus, Jordan & Evermann, Fishes North and Mid. Amer., pt. 1, p. 471, 1898; after Gilbert. Scofield
Report Fur-Seal Invest., pt. hi, p. 495, 1898, Arctic Sea off Herschel Island.

Habitat: Mackenzie River Basin.

The herring of Great Bear Lake is known from Richardson’s description and excellent figure, and
from specimens taken in 1893 by the artist, Miss Elizabeth Taylor. From these specimens now before
us the following description has been prepared. Two specimens were also obtained by Scofield & Seale
in the Arctic Sea off Herschel Island. The species has a very long, compressed body and a large adipose
fin. It is nearest in its relationship to L ontariensis, but the differences are obvious. In Richardson’s
figure the adipose fin is represented as far too small and too far back, but it is to be remembered that
this figure is taken from a dried skin.

Head small, 5 to 5.33- depth 4.33 to 4.6; eye 5 ; dorsal 1 1 or 12 developed rays; anal 1 1 or 12; scales
85 to 87, 1 1 or 12 in an oblique series downward and forward from front of dorsal to lateral line. Eye
slightly less than length of snout, 1.5 times in interorbital width. Body slender, elongate, the curve
of back and belly about equal, the greatest depth exceeding length of head; snout narrow, almost
vertically truncate when mouth is closed, the lower jaw fitting within the upper, but the mouth not
inferior; distance from snout to nape 2.60 to 3 in distance between nape and front of dorsal; head much
smaller in one of our specimens than in the other, mouth oblique, with rather slender maxillary, which
extends to vertical midway between front and middle of pupil, its length from tip to articulation equaling
distance from end of snout to front of pupil, and contained 3.66 to 3.8 in length of head; supplemental
maxillary bone probably broader than in L. artedi, from .6 to .66 greatest width of maxillary; suborbitals
very narrow, their least width less than half diameter of pupil; supraorbital bone large, its width 2.5
to 2 66 in its length. Gillrakers very long and slender, the longest slightly more than .66 length of
eye, 16+28 in number in each specimen. Front of dorsal slightly nearer tip of snout than base of
upper rudimentary dorsal rays (the fins are mutilated, so that their length can not be given); adipose
fin large, inserted vertically above last anal rays, its height from tip to posterior end of base equaling
vertical diameter of eye. Color silvery. As pointed out by Doctor Gunther, this northern form differs
from L. artedi in its shorter head and smaller eye. It seems also to have the premaxillaries placed
at a greater angle than in L. artedi.

Leucichthys laurettse (Bean) Lauretta Whitefish.

Coregonus laurettas Bean, Proc. U. S. Nat. Mus., vol. iv, 1881, p. 156, Point Barrow, Alaska; type no. 27695; coll.
Capt. Calvin L. Hooper.

Argyrosomus laurettce, Jordan & Evermann, Fishes North and Mid. Amer., pt. hi, p. 471, 1898. Evermann & Smith,
Rept. U. S Fish Comm. 1894. p. 374, pi. 25 (1896) Point Barrow. Evermann & Goldsborough, Bull. Bureau
Fisheries, vol. xxvi, 1906 (1907), p. 235, Point Barrow, Port Clarence, Yukon River at Nulato, Meade River,
Kuaru River, Elson Bay, Nushagak River, Naknek River.

Habitat: Lakes and streams of northern and western Alaska.

This species is apparently common in northern Alaska. It seems to be an ally of L lucidus, having
the adipose fin large, the caudal peduncle slender, and the pectoral not reaching halfway to ventrals.
The fins are perhaps larger than in L. lucidus, the head smaller and the body deeper.

The following is the substance of Doctor Bean’s account of this species:

Head 5; depth 4; eye 4.5 to 5; dorsal 12; anal 11; ventral 12; scales 10-84 to 95-10, 84 to 87 in
specimens examined. Body robust, the back elevated; head small and slender, the small eye not
longer than snout; distance from nape to front of snout 2.5 times in its distance from dorsal; maxillary
about reaching middle of eye, 3.5 in head, its supplemental bone half its length; lower jaw very slightly
longer than upper; mandible 2.33 in head; lingual teeth present; gillrakers long and numerous, 10+25;
ventral scale not half length of fin; pectoral short, not reaching halfw'ay to ventrals. Scales smaller
than in L. artedi, 16 cross series under base of dorsal. Alaska, from Yukon River northward to Point
Barrow, generally common. Apparently very close to L. lucidus, but the base of dorsal longer.

BULLETIN of the bureau of FISHERIES.

Leucichthys alascanus (Scofield) . A retie Lake Herring.

Argyrosomus alascanus Scofield, in Jordan & Evermann, Fishes North and Mid. Amer., pt. hi, p. 2817, Nov. 28.
1898. and in Jordan, Report Fur-Seal Invest., pt. hi, p. 495, pi. xm, 1898, Point Hope. Grantley Harbor, Arctic Sea.

Habitat: Arctic Alaska, entering the sea.

This species is allied to Leucichthys sisco, but has the body less elongate and the caudal peduncle
stouter. The pectoral, as in L. artedi, reaches more than halfway to the ventrals. The adipose fin is
said to be large, but in Scofield’s type and as shown in his figure, it is slender and moderately long,
midway in size between sisco and harengus. The ventrals are short, but they reach more than halfway
to the anal, a character which will probably separate the species from harengus.

It is not certain that this species differs from Leucichthys laurettce of the same region. The body
in the latter is deeper and the head smaller, but these may not be trustworthy characters.

The species is known only from the specimens taken by Scofield & Seale. It is described as
follows by Scofield :

Head 4.25; depth about 4; dorsal 12; anal 12; scales 10-85-9; eye a little shorter than snout,
5 in head, 1.33 in interorbital space; head wedge-shaped, the upper and lower profiles straight and
meeting with a sharp angle at the snout. Viewed from above the snout is blunt, almost square, the
narrow, pale, rounded tip of the lower jaw slightly projecting; mouth oblique, the distance from tip
of snout to tip of maxillary equal to distance from tip of snout to center of pupil; the maxillary
from its anterior articulation is contained 3.5 in the head, its width 3 in its length, its upper anterior
edge closing under maxillary ; mandible 2.33 in head, its articulation with the quadrate bone beneath the
posterior edge of the eye ; width of supplemental bone a little more than .5 width of maxillary ; preorbital
broad, its greatest width equaling .37 of its length, or diameter of pupil; width of supraorbital equaling
.28 of its length; gillrakers 12 to 14+21 to 23, long and slender, the longest .66 diameter of the eye;
tongue, vomer, and palatine without teeth; distance from tip of snout to nape equaling .5 distance from
nape to front of dorsal, or .66 length of head; adipose fin large, ventral scale .5 length of fin; longest
dorsal ray 1.5 in head; longest anal ray 2 in head; pectoral reaching more than halfway to ventrals;
ventrals reaching .66 distance to vent; caudal forked for a little more than .5 its length. Color dusky
above, silvery beneath; the dorsal, adipose fin, tips of caudal rays, and upper side of anterior pectoral
rays dusky; fins otherwise pale. But three specimens of this fish were obtained — one in salt water at
Point Hope, the other two in brackish water at Grantley Harbor. The largest one is 10.5 inches in length.

Leucichthys pusillus (Bean). Least Lake Herring.

Coregonus pusillus Bean, Proc. U. S. Nat. Mus., vol. xi, 1888, p. 526. Kobuk River. Alaska, type, 38366: coll.
Chas. H. Townsend.

Argyrosomus pusillus, Jordan & Evermann, Fishes North and Mid. Amer., pt. 1, p. 470, 1898, after Bean. Ever-
mann & Smith, Rept. U. S. Fish Comm. 1894, p. 312. pi. 23 (1896). Scofield. Fur-Seal Invest., pt. hi, p. 494,
1898, Grantley Harbor. Barter Island, Naknek River, Nushagak River. Evermann & Goldsborough, Bull.
Bureau Fisheries, vol. xxvi, 1906 (1907), p. 235, Lake Bennett at Caribou Crossing; coll. Jordan & Ever-
mann, with description.

Habitat: Lakes of Yukon basin and Alaska generally.

This is one of the smallest of the American species, rarely reaching a foot in length, and the flesh,
which is said to be bony, is mainly used as food for dogs. The fish is said to be widely distributed
throughout northern and western Alaska. Our specimens are from Grantley Harbor. Scofield & Seale
found it in the Arctic Sea and about Bristol Bay. It is a slender species with long lower jaw, large
adipose fin, the pectoral reaching more than halfway to the ventrals, and usually the dorsal fin is spotted
and the fins are all high. It is a well-marked species, probably nearest L. alascanus.

The following is the substance of Doctor Bean’s account:

Head 5; depth 5; eye 3.75 in head; dorsal 10; anal 12; ventral 11; scales 10-91-9 Body rather
elongate, compressed. Form of mouth as in L. artedi, the lower jaw considerably projecting; maxil-
lary broad, with rather broad supplemental bone, three times as long as wide, extending not quite to
middle of the very large eye, its length 3.33 in head; preorbital extremely narrow; mandible 2.33 in
head. Teeth none, or reduced to minute asperities on the tongue. Gillrakers numerous, very long and
slender, 49 in all. Dorsal very high, much higher than long, its last rays rapidly shortened, the first
rays twice length of base of fin; caudal large, well forked; anal small, ventral inserted under middle of
dorsal, very long, .83 length of head; pectoral the same length. Scales as in L. artedi. Steel-bluish

SALMONOID FISHES OF THE GREAT LAKES.

above, with many dark points; belly white; dorsal and caudal mostly blackish; pectorals and ventrals
tipped with black; eye blackish, the iris silvery. Length a foot or less. Yukon River to Bering Sea
and northward, ascending rivers.

To this Evermann & Goldsborough add the following from specimens from Lake Bennett at Cari-
bou Crossing:

Head 4.67 in body; depth 5.5; eye 3.75 in head; dorsal 10; anal 12; ventral n; scales 10-90-8.

Body rather elongate, compressed; mouth oblique, gape rather small, extending back about half the
length of the maxillaries; lower jaw considerably projecting; maxillary broad, somewhat curved, not
extending much beyond the anterior margin of orbit, its length 3.13 in head; mandible long, reaching
to below middle of pupil, 2.3 in head; teeth almost microscopic in both jaws, none on tongue; gillrakers
long, slender, and numerous, 10+26 and 13+28; dorsal high, its longest ray (about the third) about

I. 3 in head and about twice length of base; base of dorsal 2.5 in head; dorsal rays shortening rapidly
after third and fourth, leaving the margin of the fin very slightly concave; insertion of dorsal midway
between tip of snout and a point about halfway between adipose and caudal fins; caudal large, equally
forked, both lobes and indentation acutish; anal low, its longest ray 2.25 in head, its base 2 in head, its pos-
terior margin slightly concave; ventrals inserted somewhat behind origin of dorsal, reaching about ^dis-
tance to origin of anal, the length of their longest rays about 1.3 in head; pectoral equaling ventral.

Bluish above, with minute black punctulations; sides below lateral line and a short distance above
silvery, belly white; dorsal and caudal almost imperceptibly dusky; other fins wholly plain; iris silvery
a narrow blackish ring about the orbit plainest above and below.

Leucichthys artedi (Le Sueur). Lake Herring; Erie Herring; Common Lake Herring; Grayback.

Coregonus artedi Le Sueur, Joum. Ac. Nat. Sci. Phila., vol. i, 1818, p. 231, Lake Erie (at Buffalo) and Niagara
River (Lewistown); description inadequate. Jordan & Gilbert, Synopsis, p. 301, 1883.

Argyrosomus artedi, Evermann & Smith, Rept. U. S. Fish Comm. 1894, p. 305, in part (not plate). Jordan &
Evermann, Fishes North and Mid. Amer., pt. 1, p. 468, 1898. Of recent authors generally.

Coregonus clupeiformis, Gunther, Cat., vol. vi, p. 198 (not Salmo clupeaformis Mitchill).

The name artedi applied by Le Sueur to specimens from near Buffalo must be retained for the
common lake herring of Lake Erie.

This species is characterized by its relatively deep elliptical form with compressed sides and rather
stout caudal peduncle, in connection with the large adipose fin. All the other species of this subgenus,
bisse/li and eriensis excepted, are much more slender in all their parts. The average length of this
species in Lake Erie is 12 to 14 inches and the weight about 14 or 15 ounces. The fishermen of Lake
Erie are in general entirely satisfied with a mesh of 3 inches to catch artedi and eriensis, while for the
other species a mesh of 2X inches is required, and this is too coarse for the form called supernas. This
species is also paler in color than any of the others, eriensis excepted, and lacks the blue shades character-
istic of huronius and ontariensis . The flesh in artedi, as in huronius, is much inferior to that of eriensis.

This is the most abundant of the lake herrings so far as market fishing is concerned. It abounds
in Lake Erie, especially in its southern parts. It ascends to Lake St. Clair, and we have one fine
example from Lake Huron at Port Huron, where it was taken with a multitude of huronius. We
have also examples obtained by Dr. Seth E. Meek at Toronto. As Doctor Meek was present at the cap-
ture of the Toronto specimens, there is no doubt that they came from Lake Ontario, but we know
also that whitefish and herring fry have been often transferred from Lake Erie to other lakes, and
it is possible that L. artedi is not native to Lake Ontario.

The specimens here figured are from Cleveland and Toronto. The fish from the latter place is
a ripe female with unusually deep body. Others at hand for comparison are five from Erie, one
from Port Maitland, three from Toronto, and one from Port Huron (Lake Huron). The presence of
a specimen at the latter locality indicates the tendency of these closely allied species to invade one
another’s territory.

The Lake Erie herring is described as follows, from eleven specimens, between 8.3 inches and

I I. 8 inches long, from Lake Erie off Cleveland:

Head 4.4 in body to base of caudal; depth of body 3 to 4; length of caudal peduncle from last
rays of anal to first of caudal 2 to 2.75 in head, its depth 2 to 2.5; eye about 4.4; snout 4; interor-
bital space slightly greater than length of snout; maxillary measuring from tip of snout 2.87 in head;

48299° — Bull. 29 — 11 2

bulletin of the bureau of fisheries.

width of opercle 3.33; dorsal rays (fully developed) 10 or n; anal 12; scales 8 — 69 to 75 — 7, between
occiput and dorsal 30 to 35; branchiostegals 8 or 9; gillrakers 15 or 16+27 to 31 on first gill-arch.

Body not elongated, but somewhat compressed and usually deep; dorsal and ventral outlines
similar and usually symmetrical, greatest depth at insertion of dorsal; width about 2.12 in depth;
caudal peduncle compressed, deep, frequently deeper than long. Head small, pointed, with narrow
snout; jaws subequal, the premaxillaries variably oblique; maxillary moderate in length, extending
to or slightly beyond perpendicular from front margin of pupil, its width about 3 in length; supple-

Fig. 8. — Leucichthys ariedi (Le Sueur). Lake herring. ^Drawn from a specimen 12 inches long
collected in Lake Erie off Cleveland.)

mentary bone large, well developed; very minute teeth on tongue, absent elsewhere; distance from
snout to occiput less than half distance from occiput to dorsal. Scales moderately large, firm, slightly
broader anteriorly; lateral line straight, prominent, nearer back than belly.

Dorsal fin inserted midway between snout and base of caudal, its base about 2 in head, its height
about twice maxillary length, but variable, margin truncate or slightly concave; adipose large, its
length from insertion to tip contained 3 to 4 in head; pectoral usually long, reaching at least half

Fig. 9. — Leucichthys ariedi (Le Sueur) Lake herring. Female. (Drawn from a specimen 12
inches long from the Toronto market.)

distance to ventrals (contrasting with L. ontariensis) , but very variable; ventral equal or slightly less in
length than height of dorsal, rather shorter than usual; anal very short, its longest ray usually some-
what longer than depth of caudal peduncle, its base about equal to that measurement, margin con.
cave; caudal rather short, not very deeply forked.

Color in spirits silvery, darker above; somewhat less silvery and colorless ventrally; dorsal and
caudal slightly edged with black, but comparatively pale; pectorals, anal, and ventrals colorless, save
for an occasional stipple of black.

SALMONOID FISHES OF THE GREAT FAKES.

Comparison of specimens of Leucichthys artedi.

Cleveland.

Erie, Pa.

Port

Huron.

Port

Maitland.

Toronto.

Specimen no . .

5252

5251

523

5223

5225

4930

493 7

Length without caudal mm. .

252

245

260

235

200

262

205

Dorsal rays

1 1

I I

1 1

Anal rays

1 1

1 2

Scales

8-74-7

8-76-7

8 rA- 71-7

9-69-8

8-72-7

8-71-7

8-75-7

Scales between occiput and dorsal fin .

Branchiostegals

8 or 7

Gillrakers

Comparative measurements:0

l6 +27

l6+29

16 +29

Evisc.

15 +29

16 +29

16 +31

Head

O. 22

O. 23

0. 23

0. 235

O. 23

0. 225

0. 24

Depth

Caudal peduncle —

. 28

• 30

. 26

• 23

. 28

• 27

Length &

. 092

. I I

• 09

. IO

• 095

. 1 1

. 11

Depth

. IO

■ 09

■ 085

• 09

. 09

Eye

• 05

• 055

•055

• 05

Snout from eye

• 055

. 055

. 06

• 055

. 06

Interorbital space

. 065

• 07

. 06s

. 06

■ 065

. 06

Maxillary length from tip of snout.

. 08

.08

. 08

. 09

•075

. 08

Snout to occiput

• 15

• 155

. 16

• 165

• 155

• 145

■ IS

Ventrals to pectorals

Pectoral length in ventral-pectoral

.31

■ 34

• 33

•335

• 30

•35

• 31

distance

2. OO

I . 89

I- 75

2. OO

1 . 89

Pectoral length

■ 17

■ 175

• 17

- 17

■ 17

. 165

. 17

Ventral length

• 17

■ 175

• 17

■ 17

•( 1 7

. 165

• 17

Dorsal height

. 18

. 19

. 18

. l6

■ 175

. 16

. 17

Adipose length

• 07

. 08

. 06

• 07

• 075

■ 07

Anal height

• 105

. 12

• 115

. IO

. 12

• 05

. IO

a Measurements made in decimal fractions of body length without caudal unless otherwise specified.
b Length from anal to first caudal rays.

Comparison of L. artedi and L. eriensis.

L. artedi, Erie, Pa.

L. eriensis , Port
Stanley.

Specimen no . .

49i

493

13083 (cotype).

Length without caudal mm . .

285

305

310

Dorsal rays (fully developed)

I I

Anal rays

1 1

I I

Scales

8-65-7

8-73-7

7 A-Si-S

Scales between occiput and dorsal fin

Branchiostegals

Gillrakers

14 +31

17 +32

Sexual condition

Spawning.

Not ripe.

Comparative measurements: a

Head

0. 22

O. 22

Depth

• 32

• 34

. 28

Caudal peduncle —

Length b

■ 09

.08

Depth

. IO

. 11

• 095

Eye

• 05

■ 055

. 04

Snout

• 055

• 05

Interorbital space

• 065

• 07

. 065

Maxillary length from tip of snout

• 075

■ 075

• 07

Snout to occiput

• 14

• 15

• 14

Ventrals to pectorals

• 34

• 36

• 33

Pectorals in pectoral-ventral distance

2. OO

2. 20

2. OO

Pectoral length

• 17

■ 165

Ventral length

. 165

• 17

• 15

Dorsal height

. 16

• i7

• 15

Adipose length

065

• 075

Anal height

. 1 1

. 1 2

a Measurements in hundredths of body length to base of caudal.
b From last anal to first caudal rays.

BULLETIN OF THE BUREAU OF FISHERIES.

Leucichthys artedi bisselli (Bollman). Rawson Lake Herring; Bissell’s Herring.

Coregonus tullibee bisselli Bollman, Bull. U. S. Fish Comm., vol. viii, p. 223, 1888, Rawson Lake and Howard Lake*
Michigan.

Argyrosomus tullibee bisselli, Jordan & Evermann, Fishes North and Mid. Amer., pt. 1, p. 473, 1898.

Habitat: Glacial lakes of southern Michigan once tributary to Lake Erie.

A large plump lake herring was described by Charles Harvey Bollman in 1888, from Rawson and
Howard lakes at Schoolcraft, Kalamazoo County, Mich., in connection with his survey of the fish
fauna of southern Michigan. Because of its robust form it was regarded by Bollman as a subspecies
of the tullibee. Its relationships are, however, wholly with artedi, of which it may be regarded
as a subspecies. The accompanying description and figure are taken by us from Bollman’s type, no.
40619, U. S. National Museum:

Head contained 4.5 in length without caudal; depth 3.5; depth of caudal peduncle 2.33 in head;
eye 5.2; snout 5; interorbital space 3.66; length of maxillary from tip of snout 3.25 in head; dorsal 11;
anal 1 1 ; scales in lateral line 77, between dorsal and lateral line 10, between ventral and lateral line 9,
and between occiput and dorsal 30; branchiostegals 9. Gillrakers 16-1-29,0.75 diameter of eye in length.

Body strongly compressed, its width from side to side contained 1.83 in head; dorsal outline
arched upward strongly from head; ventral outline convex; head flat dorsally, pointed; snout rounded;

Fig. 10. — Leucichthys artedi bisselli (Bollman). Rawson Lake herring. (Drawn from a specimen
13 inches long, collected in Howard Lake, Michigan.)

lower jaw slightly longer than upper; maxillary extending to below anterior edge of pupil, the supple-
mental parts three times as long as broad; width of opercle 3 in head. Dorsal inserted midway between
snout and caudal base, its longest ray 1.5 in head; adipose base 6 in head, length from insertion to
tip 3.33 in head; anal base 2.33 in head, longest ray 2.25, and its scale 2.5 in ray length.

Color in spirits, light olive, somewhat darker above; sides silvery; dorsal fin clear, edged with
dark, other fins clear.

This subspecies is slightly more robust than L. artedi, but no differences of importance set it off
from the lake form from which it is no doubt derived.

Leucichthys eriensis (Jordan 8e Evermann). Jumbo Herring; Erie Great Herring.

Argyrosomus eriensis Jordan & Evermann, Proc. U. S. Nat. Mus., vol. xxxvi, March 3, 1909, p. 165, fig. 1, Lake
Erie at Port Stanley.

Habitat: Lake Erie, northward.

This species inhabits especially the north shore of I.ake Erie, where it is extremely abundant. As
a food fish it is far superior to the other lake herrings and is as good as the best whitefish. The original
type came from Port Stanley. Besides the type we have examples from Port Burwell and Point Ron-
deau. Reports of jumbo herring from Toronto have reached us, but these probably refer to large
examples of the local species. As the fishes from Port Stanley are largely sold in Toronto, it is possible
that the reference is to Lake Erie examples of the present species

SALMONOID FISHES OF THE GREAT LAKES.

The jumbo herring has been confounded with the tullibee, with which it has nothing in common
save the robust form. The name “mongrel whitefish” belongs to eriensis , not to the tullibee. The
nearest relative of L. eriensis is L. arfedi, from which it differs in the much more robust form, deeper
nape, smaller head, and firmer scales.

The following is the original account :

Head 4.4 in length, measured to base of caudal; depth 3.4; depth of caudal peduncle 2.2 in head;
eye 5.2; snout 3.75; interorbital space 3.25; length of maxillary from tip of snout 3; dorsal 10; anal
12; scales in lateral line 71 ; between lateral line and origin of dorsal 8; between occiput and dorsal 32.

Body very deep, its width contained 1.4 times in head; dorsal outline curved abruptly upward
behind occiput; dorsal contour of head straight; snout pointed, though rather blunt at tip; jawrs about
equal, the lower closing just beneath the upper at tip; maxillary extending to a point beneath anterior
edge of pupil, the supplemental part about 3 times as long as wide. Gillrakers on first arch 16+29,
very slender, the longest equal in length to diameter of orbit. Scales firmly attached. Dorsal inserted
about midway between tip of snout and base of caudal, the highest (first) ray contained 1.5 times in
length of head; height of adipose dorsal equal to 1.5 times the length of its base; height of anal con-
tained 2 times in length of head; outline of both dorsal and anal slightly concave; origin of ventral
below anterior part of dorsal, length of fin contained 1.5 in head; pectoral 1.4 in head.

Fig. 11. — Leucichthys eriensis (Jordan & Evermann). Lake Erie Herring; Jumbo Herring. Fromthetype.

Color in spirits silvery, dusky on upper parts, but without blue shades in life; distal portion of
dorsal, outer part of caudal, and edge and tip of pectoral dusky; other fins white.

Type (no. 62515, U. S. Nat. Mus.) from Lake Erie at Port Stanley, Ontario, measuring 16 % inches
in length, and collected by the writers. This represents the maximum size of the species as seen by
us. Its weight when fresh was 2^ pounds. A cotype, 14+f inches long, no. 13083, Stanford University
collection, obtained at the same time, is a little smaller and slightly darker in color, the anal having a
terminal dusky cloud. It has 11 dorsal and 11 anal rays.

This species is very abundant along the northern shore of Lake Erie about the first of August. It
is also occasionally taken in the southern part of Lake Huron, but it seems to be unknown in Lake
Superior, and we did not hear of it in Lake Ontario. On the date of our visit to Port Stanley,
July 29, 1908, about 1,500 pounds were taken in the gill nets. The largest of these weighed 2 pounds
and w’ere about 18 inches in length. The bulk of the catch was, however, about 14 inches in length.
It is said of this species that there is a “great spurt,” or large run, in the spring and a short one in the
autumn before the spawning time in November.

The jumbo herring was also seen at Port Burwell, where large numbers are smoked, having an
excellent flavor as thus prepared. Many others from Point Rondeau, Ontario, were seen in the Detroit
market.

Leucichthys eriensis is characteristic of the northern part of Lake Erie, although other species,
Leucichthys artedi, the common lake herring, and Leucichthys sisco huronius are found in the same lake.
It is said to have been virtually unknown until ten years ago, but is rapidly increasing in abundance.

bulletin of the bureau of fisheries.

Fishermen claim that it is found in middle water, not at the surface nor at the bottom. As a food fish
it is far superior to any other lake herring, being as delicate and rich as the best whitefishes, Corcgonus
albus and Coregonus clupeajormis. It is therefore a species worthy of careful attention from the propa-
gators of fishes. Most of the fishermen claim never to have seen examples of 2 or 3 pounds until within
four or five years. It is locally known as the jumbo herring because it reaches a larger size than any
other lake herring except the tullibee of the northwestern lakes ( Leucichthys tullibee).

It is believed by many fishermen that the jumbo herring is the product of a cross between the Erie
whitefisli ( Coregonus albus) and the lake herring ( Leucichthys arledi). This belief is without founda-
tion. It rests on the fact that at the Put-in Bay hatchery attempts have been made to fertilize white-
fish eggs with the milt of the lake herring, in default of the milt of its own species. To test this matter
Mr. Frank N. Clark, of the hatchery at Northville, Mich., undertook the same experiment under
carefully prepared conditions. In no case was the egg of a whitefisli fertilized by the milt of the lake
herring, and the hybridization of the two species is quite improbable.

Subgenus CISCO Jordan & Evermann, new subgenus.

Cicso Jordan & Evermann, new subgenus (type, Argyrosomus nigripinnis Gill).

The depths of the Great Lakes are inhabited by species of Leucichthys, locally known as blackfin,
bluefin, cisco, longjaw, bloater, kiyi, chub, etc., differing somewhat from any of the shore species of the
genus. In nearly every favorable locality three forms of these fishes are found, representing the three
nrincipal species, prognathus (with supernas and johannce), nigripinnis (with cyanopterus), and hoyi
(with zenithicus). These fishes are much softer in flesh and more delicate than the ordinary lake
herring. They spawn earlier, in summer, and are rarely taken in water of less than 60 fathoms. None
has been found in Georgian Bay or Lake Erie. They inhabit the western part of Lake Ontario, the
northwestern part of Lake Huron, the whole length of Lake Michigan, and the middle southern part of
Lake Superior.

Leucichthys supernas Jordan & Evermann, new species. Cisco of Lake Superior.

Type, no. 64679, U. S. National Museum, a specimen about 11 inches long, from Lake Superior off the mouth of
Knife River, near Duluth; coll., Doctor Jordan.

Habitat: Deep waters of Lake Superior.

The cisco, as it is called about Lake Superior, is a fine silvery species, found in waters of 50 fathoms
or more, and is regarded as an excellent food fish. It is near Leucichthys prognathus and L. johannce

Fig. 12. — Leucichthys supernas Jordan & Evermann, new species. Cisco of Lake Superior.
(Drawn from the type, a specimen. 11.5 inches long, collected in Knife River, Lake
Superior, off Duluth, Minn.)

but is a better food fish than these, is of firmer flesh, and reaches a larger size. It also approaches
somewhat Leucichthys harengus of the shore waters of the same region.

Leucichthys supernas is especially characteristic of the waters to the west qf the Keweenaw' penin-
sula, where it is found in company with the bluefin, Leucichthys cyanopterus, and the longjaw, Leucichthys
zenithicus, and also the siscowet, which preys on all three. The bluefin is a still better fish, reaching a
larger size, while the longjaw is inferior and much less fat

SALMONOID FISHES OF THE GREAT LAKES.

Description of type: Head 4.4 in body to base of caudal fin; depth of body 4; length of caudal
peduncle from last anal to first caudaf rays 2 in head, its depth 2.87; eye 4.6; snout 3.87 to 4; inter-
orbital space 3.5; length of maxillary from tip of snout 2.87; dorsal 10 (developed rays); anal 12;
scales 8-76-7; branchiostegals 9; gillrakers 15 + 29, length .66 eye diameter.

Body somewhat elongate, moderately deep, and compressed, very much resembling L. artedi;
arched between snout and insertion of dorsal more than from insertion of dorsal to caudal, slightly
more convex ventrally; caudal peduncle long, not deep as in L. artedi (some specimens of which it
approaches, however), and compressed; head smaller than in L. prognathus, not full at nape; snout
pointed, compressed, its outline continued by premaxillaries, lower jaw slightly projecting; maxillaries
short in proportion to snout, reaching to anterior edge of pupil; distance from snout to occiput slightly
less than half distance from occiput to dorsal insertion.

Lateral line straight, scales moderate, thin.

Dorsal fin inserted midway between snout and base of caudal, low, more so than in L. artedi, its
longest ray a trifle less than .66 head, its base .66 of ray length; adipose fin rather small, as long as
snout, measuring from insertion to free end; caudal widely forked; anal rather low, its longest ray 2.3
in head, its base equal to ray length, its margin nearly truncate; pectorals and ventrals rather shorter
than in L. artedi, being slightly longer than longest dorsal ray, the former not reaching more than half
way to ventrals.

Color in spirits silvery, slightly darker above, especially on removal of scales; cheeks silvery;
dorsal fin dark on distal half, caudal broadly edged with black, other fins colorless save for very slight
stipple on pectoral.

As already indicated, this species, although a deep-water form, is very close to L. harengus, of
which it is probably a deep-water variant. It is perhaps through L. supernas that the other deep-water
forms are derived. Compared with L. harengus, L. supernas has a slightly deeper tail and the body is
less slender. Two specimens of cisco, from off Knife River, near Duluth, differ from the others in the
number of gillrakers, the number being about n + 21. Such variations were also noted by Evermann
& Smith. These specimens are a little more robust than the others, with the adipose fin perhaps a
trifle larger. For the present we can only record them as a variant of L. supernas. They differ from
L. johannce in the slightly shorter snout, broader interorbital space, deeper body, and firmer scales.

A copepod, apparently the same, is parasitic on both L. supernas and L. harengus.

Leucichthys prognathus (H. M. Smith). Cisco of Lake Ontario; Ontario Longjaw; Bloater; “Chub. ”

Coregonus prognathus Smith, Bull. TJ. S. Fish Comm., vol. xiv, 1894, p. 4, pi. 1, fig. 3, Lake Ontario at Wilson,
New York ; type no. 45568, U. S. National Museum; coll., John S. Wilson.

Argyrosomus prognathus, Evermann & Smith, Rept. U. S. Fish Comm. 1894, p. 314, 1896, pi. 26, Lake Ontario;
Jordan & Evermann, Fishes North and Mid. Amer., pt. 1, p. 471, 1898 (after Smith).

Habitat: Deep waters of Lake Ontario, in depths of 60 fathoms and more.

This species is abundant in the western part of Lake Ontario in deep water. Whether any fishes
from Lake Huron or Lake Michigan (here recorded as L. johannce) should be referred to this species is
uncertain. It is distinguished by its projecting lower jaw and by the thick body. When taken from
deep water the viscera become inflated under reduced pressure, hence the name “bloater” given to
this and to the related species in the upper lakes. Our specimens of this species were taken by
Dr. Seth E. Meek in Lake Ontario off Toronto.

The following description is from a ripe female, 8+( inches long, from off Toronto, no. 4922 in
the table on page 26.

Head 4 in length to base of caudal; depth 3.5 (greater on account of ripe condition); length of
caudal peduncle from last anal to first caudal ray 2.5 in head, depth nearly 3.5; eye 4; snout 4; inter-
orbital space 3.57; length of maxillary from tip of snout 2.6; dorsal 10 (developed rays); anal n;
scales 8-71-7; branchiostegals 8; gillrakers 15 + 29.

Body moderately elongate, more convex ventrally, appearing, despite ripe condition of specimen,
deeper than specimens from Lake Huron; caudal peduncle slender, tapering much, especially on ventral
outline from anus; head large, thick at opercle, nape full and humped or strongly curved from occiput

BULLETIN OF THE BUREAU OF FISHERIES.

to insertion of dorsal; snout bluntly rounded, broad; lower jaw projecting markedly, a slight angle at
symphysis of dentaries, giving jaw a slightly hooked appearance; premaxillaries not breaking contour
of head noticeably; lateral projection of anterior ends of preorbitals and maxillaries greater than usual;
maxillaries extending to below middle third of eye, their supplemental one-half their breadth and
length; distance from snout to occiput long, half distance between dorsal and occiput; opercular breadth
equal to snout.

Lateral line rising slightly anteriorly, but nearly straight; scales moderate, slightly larger ante-
riorly, easily detached.

Dorsal fin inserted nearer base of caudal than snout, moderately high, its longest ray about 1.5 in
head, its base 2.5, its margin truncate; adipose moderate (somewhat shrunken in preservation), slightly
shorter from insertion to tip than snout; ventrals and pectorals a trifle, the latter noticeably, longer
than dorsal, pectoral reaching half way to ventrals; anal slightly concave; adipose eyelids and pectoral
fold not prominent; caudal forked widely but not deeply.

Color in spirits, suffused with brownish, darker above than in Lake Huron specimens; lateral line
marked with line of distinct black in specimen at hand; fins clear, dorsal and caudal dusky on distal
halves; ventrals, anal, and pectorals with only slight traces of black stipples on first rays and margins.

From the bloater of Lake Michigan, which we here call Leucichthys johannce, the Ontario fish differs
in its darker coloration, the more projecting lower jaw, the slenderer caudal peduncle, the greater depth
of the body, and the greater distance between the pectorals and ventrals. From typical examples of
Leucichthys johannce, it also differs in the much larger number of gillrakers. But as stated later, part
of our specimens from Lake Huron, referred to L. johannce, have the gillrakers much as in L. prognathus.
What this difference means is a matter demanding further study.

Leucichthys johannae (Wagner). Lake Michigan Cisco; Bloater oj Lake Michigan. (PI. in. )

Argyrosomus johannce Wagner, Science, n. s., vol. xxxi, no. 807, p. 957-958, June 17, 1910, Lake Michigan, in about
25 fathoms, some 18 miles off Racine, Wis. Type no. 372c!, Wisconsin Geological and Natural History Survey.

The bloater is very common in the northwestern part of Lake Huron in deep water, and also for
the whole length of Lake Michigan. On these lakes it is not often taken to the markets, and is not
highly valued as food. It is a great nuisance to the fishermen, large schools entering the nets and
tangling them, although the mesh is large enough to allow escape.

Whether the form in Lake Huron and Lake Michigan is really distinct from the prognathus of Lake
Ontario is a matter we can not finally determine. Some examples of johannce may be known at once
by the few gillrakers, but this character is lost in Lake Huron examples, which, for the present, we are
forced to refer to the same species.

The following is a description from four specimens, 7 to 10 inches in length, two from Lake Michigan
near Chicago and two from Lake Huron off Cheboygan, Mich.:

Head 4.2 in body length to base of caudal; depth of body equal to head; length of caudal peduncle
from last anal to first caudal ray 2.4 in head, its depth 3.5; eye 4.4; snout 3.75 in head; interorbital
space equal to snout; length of maxillary from tip of snout 2.66 in head; dorsal 11 (developed rays);
anal 12; scales 8-76-8 (8-74 to 80-7 or 8), branchiostegals 9; gillrakers on first arch 11 + 23.

Body moderately elongate, not greatly compressed nor deep, its depth 1.66 its width; more convex
ventrally (possibly on account of being brought from a depth and blown out by reduced pressure) ;
without nuchal hump; caudal peduncle long, not deep, somewhat compressed; head moderately long,
somewhat less than the average of L. zenithicus; distance from snout to occiput moderately long,
equal to half distance from occiput to insertion of dorsal; eye moderate; maxillary rather long, reaching
to below anterior third of pupil, without decurving strongly on free edge from junction with premaxil-
laries; premaxillaries continuing contour of head at but slight angle; snout rather long and rounded,
lower jaw projecting beyond it somewhat with a small symphyseal angle; suborbitals narrow, pre-
orbitals rather broad. Lateral line straight, scales moderate in size, thin and flexible. Dorsal fin
inserted midway between snout and base of caudal, moderately high, border truncate, adipose moderate,
from insertion to free end somewhat longer than snout; pectoral and ventral rather short, latter not

SALMONOID FISHES OF THE GREAT LAKES. 25

reaching beyond halfway to former, about equal to distance between snout and occiput. Anal rather
short, 2.4 in head, concave.

Color in spirits silvery, suffused with brownish and slight dark above lateral line, below silvery
white or colorless, cheeks silvery ; fins colorless, save for slight edging of black on dorsal and caudal.

Besides these specimens, which resemble each other closely and belong to the same species, we
have others not differing at all externally, in which the average number of gillrakers runs from 12+25
to 14+28. All these are from Lake Huron, off Cheboygan, and approach Leucichthys prognathus.
Evermann & Smith (Report U. S. Fish Commission for 1894, p. 31 1) note the finding of similar examples,
five from Lake Michigan and three from Lake Superior, which they refer provisionally to hoyi, although
recognizing the close relation to prognathus . They say: “ In the numerous specimens of hoyi examined,
the average number of gillrakers was found to be 39, while for the 8 specimens here considered the
average is but 31)+” These specimens from Lake Michigan we refer to L. johannce, those from Lake
Superior provisionally to L. supernas. The specimens from Lake Michigan which differ from the
type of Leucichthys johannce we may regard for the present as a variation of the latter. We here pre-
sent a description of this form.

Description of the bloater of Lake Huron with many gillrakers ( Leucichthys johannce , var. B.):

Seven specimens from 6.25 to 9 inches in length; one 8.5 inches in length, no. 5277 here
described; all from Lake Huron, off Cheboygan, Mich.

Head 4 in length to base of caudal; depth 4; length of caudal peduncle from last ray of anal to
first of caudal 2.4 in head, depth 3.25; eye 4; snout 3.57; interorbital space 4; length of maxillary from
tip of snout 2.3 in head; dorsal 10 (developed rays); anal 12; scales 8-79-7; branchiostegals 9; gill-
rakers 14+26.

Body moderately elongate, more convex in ventral outline, not greatly compressed, its width 1.66
in body depth; caudal peduncle rather long and slender, its width 1.5 in depth; ventral outline along
base of anal tapering more abruptly to caudal peduncle than dorsal outline; head long as in L. zenithicus ;
dorsal surface slightly arched from snout to occiput, and from eye to eye; snout bluntly rounded, not
tapering much; underjaw projecting; dentaries meeting at a slight angle to form a dorsal tubercle at
symphysis; premaxillaries breaking contour of head but slightly; anterior ends of preorbitals and
maxillaries protruding laterally somewhat to give bluntly rounded appearance to snout; maxillaries not
lying closely to head along their whole length, extending to below middle third of eye; supplemental
0.5 maxillary breadth (in other specimens 0.66); distance from snout to occiput long, from 0.5 to 0.57 of
distance between occiput and dorsal fin; opercular breadth slightly more than length of snout; lateral
line straight; scales moderate in size, easily detached, and smaller posteriorly.

Dorsal fin inserted nearer base of caudal than tip of snout, moderately high, its longest ray about
1.5 in head, its base 2.5, border truncate; adipose moderate, from insertion to tip nearly equal to snout,
its height 0.33 length ; ventrals and pectorals as long as dorsal ray, pectorals reaching halfway to ventrals;
anal somewhat concave; caudal forked widely.

Color in spirits not very silvery, suffused with brownish, but slightly darker above; fins clear, save
for dusky margin of dorsal and caudal; slight trace of black on pectorals; lateral line sometimes marked
distinctly, sometimes very faintly with a line of black.

Whether Leucichthys johannce can be separated as a species from L. prognathus is uncertain; as there
can be no connecting forms, it is a distinct species or nothing.0 *

a The following is Mr. Wagner’s original description of this species:

Head. 4.1 in length to base of caudal; depth, 3.8; eye, 6.5 in head; depth of caudal peduncle, 3.1; snout, 3.4; max-
illary, 2.6; mandible, 2; height of dorsal fin, 1.5; distance from snout to dorsal, 1.9 in length; gillrakers, 10+19; longest,
1 in eye; dorsal, 10; anal, 12; scales, 9-80-8.

Body deep, not greatly compressed, back strongly arched, rising rapidly for one-half the distance from snout to dorsal,
then more gradually. Caudal peduncle high, not greatly compressed. Head small, sharply wedged-shaped, its height at
occiput 1.9 in height of body. Eye small. Lower jaw even with upper; maxillary reaching nearly to center of eye.
Gillrakers coarse and widely set. Lateral line straight. Scales large and thick, nondeciduous.

Color (in formalin): Lips and head pale; body dark above but not nearly to lateral line; quite pale below. Dorsally
some indication of stripes, longitudinally. Dorsal and caudal fins with black edges, other fins pale.

bulletin of the bureau of fisheries.

Comparison oj Leucichthys prognathus and Leucichthys johannce.

L. prog.na-
ihus,
Toronto.

L. johannce, Cheboygan.

Specimen no . .

4922

5280

5281

5279

5277

Length to base of caudal mm. .

205

210

164

160

215

Dorsal rays

1 1

Anal rays

1 1

1 2

1 1

Scales

8-71-7

8-78-7

8-70-7

8-73-7

8-79-7

Branchiostegals

Gillrakers

15 + 29

12+25

13+26

14 + 28

14 + 26

Sexual condition

Ripe $

Ripe c?

Unripe $

Comparative measurements:®

Head. . . . 7

O. 26

O. 25

Depth

• 30

• 27

. 26

• 25

• 23

Caudal peduncle —

Length

• 095

• 105

• 095

. I I

Depth

. 07

. 08

• 075

.08

Eye

. 065

. 06

■ 07

. 072

. 06

Snout

. 068

. 07

• 075

• 07

. 07

Interorbital space

. 07

• 065

. 07

■ 065

Maxillary from tip of snout

. 10

. IO

• 105

. II

Opercular breadth

• 07

• 075

• 07

Subopercular breadth

• 03

. 02

• 03

• 035

Snout to occiput

. 185

• 185

• 19

.185

Ventrals to pectorals

• 39

• 36

• 35

• 34

Pectorals in pectoral-ventral distance

2. 125

2. 20

2 . 00

1 . 80

2 . 00

Pectoral length

• 19

• 17

. 17

• 19

. 18

Ventral length

. 18

• 17

. 18

. 19

. 18

Dorsal height

. 165

• 17

■ 17

• 19

• 165

Adipose length

. 06

. 07

. 08

.08

Anal height

. 1 1

. IO

. 1 1

. 10

a Measurements in hundredths of body lengths unless otherwise specified.

Leucichthys nigripinnis (Gill). Blackpn of Lake Michigan. (PI. iv.)

Argyrosomus nigripinnis Gill Ms., in Hoy, Trans. Wis. Ac. Sci., i, p. 100, 1872, Lake Michigan off Racine; name
only. Hoy, Rept. U. S. Fish Comm, for 1872-73 (1874), p. 87, Lake Michigan off Grand Traverse. Jordan,
Rept. Geol. Surv. Ind. 1875, p. 5, Lake Michigan. Jordan & Evermann, Fishes North and Mid. Amer.,
pt. 1, p. 472, 1898, Lake Michigan, Lake Mendota, and Lake Miltona, Wisconsin. Evermann & Smith, Rept.
U. S. Fish Com. 1894, p. 317, pi. 27 (1896), Lake Michigan.

Habitat: Deep waters of Lake Michigan and certain small lakes in Wisconsin.

This is the largest of the deep-water ciscoes, and is a food fish of fine quality and of large commercial
importance in Lake Michigan. It reaches a larger size than any of the other species of Leucichthys
except eriensis, and is readily known by its black fins, in connection with its plump body and rather
large eye and mouth. In Lake Michigan the fins are all chiefly black and the fish is called blackfin.
In Lake Superior the species is replaced by the paler closely allied bluefin, Leucichthys cyanopterus.

The following description is from our single specimen, 13 inches long, taken in Lake Michigan,
off Kenosha:

Head slightly less than 4 in body length to base of caudal; depth slightly more than 4; length of
caudal peduncle from last rays of anal to first of caudal 3 in head, depth slightly greater; eye 4.66;
snout 4; interorbital space 3.5; maxillary from tip of snout 0.5 longer than snout, 2.66 in head; dorsal 1 1
(fully developed rays); anal 12; scales 8-75-8, between occiput and dorsal 34; branchiostegals 8; gill-
rakers 18+33.

Body moderately elongate, dorsal and ventral outlines symmetrical, not greatly compressed, its
width 2.33 in greatest depth; caudal peduncle short and deeper than its length. Head moderate in
length; snout not conical viewed from above, but rounded and broad; premaxillaries projecting very
obliquely forward ; lower jaw longer, with slight symphyseal angle; maxillary not quite reaching anterior
edge of pupil; distance from snout to occiput short, less than twice in distance from occiput to dorsal,
and 2.5 times opercular breadth, which is slightly shorter than snout. Lateral line straight, nearer
dorsal outline; scales moderate, of equal size anteriorly and posteriorly.

Dorsal inserted slightly nearer head than base of caudal, relatively high, equal in length of first
developed ray to the distance between the snout and occiput, a trifle more than 1.5 in head, all ray tips

SAL, MONOID FISHES OF THE GREAT LAKES.

coinciding when fin is supine, edge truncate, nearly perpendicular, base 2 in head; adipose moderate,
equal in length, from insertion to tip, to interorbital space; caudal broad, widely forked, anal moderately
high, its edge concave, first developed ray not reaching tip of last when supine; ventrals long, slightly
more so than dorsal; pectoral still longer, 1.66 in distance from pectoral to ventrals.

Color in spirits silvery, dark blue-black above, on tip of mandibles and snout, black on all fins,
saving their bases, which are clear; ventrals, pectorals, and anal with less black than other fins; body
colorless ventrally.

Leucichthys cyanopterus Jordan & Evermann, new species. Bluefin.

Type, no. 64672, U. S. National Museum, a specimen 16 inches long, from Lake Superior, off Marquette, Mich. ;
coll., Mr. August J. Anderson.

Habitat : Deep waters of Lake Superior.

This species, closely allied to the blackfin, L. nigripinnis, is here described from the type and 9
cotypes from off Marquette in Lake Superior.

Head a trifle less than 4 in body length to base of caudal; depth of body 3.75; length of caudal
peduncle from last anal ray to first of caudal 2.25 in head, its depth 2.8; eye 5; snout 3.5; interorbital
space slightly more than snout; length of maxillary from tip of snout 2.8 in head; dorsal 10 or 11
(developed rays); anal n or 12; scales 8-76 to 87-7, between occiput and dorsal about 33; branchi-
ostegals 9; gillrakers 13 or 14 + 24 to 27.

the type, a specimen 16 inches long, collected in Lake Superior off Marquette, Mich.)

Body less elongate than usual, dorsally and ventrally equally curved; depth greater than usual
not greatly compressed; width of body a trifle over twice in depth; caudal peduncle moderately long
and deep, tapering from the proximal end to the caudal, and not more compressed than the body;
head somewhat smaller than in related deep-water forms, but larger than in L. artedi; snout rounded,
lower jaw usually the longer, but meeting the projecting premaxillaries; maxillaries extending nearly
to a vertical from the front margin of pupil, and lying close to dentaries, so as to give them an oblique
relation to the ventral body plane, distance from snout to occiput slightly more than half the distance
from occiput to insertion of dorsal; opercular breadth about equal to snout or somewhat greater; eye
rather large, less than interorbital space, the latter very slightly convex, straight in profile; snout
slightly arched in profile.

Lateral line straight, slightly nearer dorsal outline; scales moderate in size, equal, save on the
caudal peduncle and on belly, showing blue-green luster when magnified. Dorsal fin inserted nearer
snout than base of caudal, moderately high, its longest ray about 1.66 in head, its base somewhat
over 2, its margin straight or slightly concave, first and last ray tips coinciding when supine; adipose
rather large but variable, about 4.33 in head, and moderately high; caudal broad, widely forked,
moderately deep; anal similar to dorsal in shape, but about 0.66 its height, its margin more concave,
its base about equal to that of dorsal; ventrals long, reaching 0.75 distance to anal, and broad ; pectoral
also long, reaching halfway or more to insertion of ventrals, and longer than the latter.

Color in spirits silvery, darker above, with a bluish tint; dorsal fin dark on first ray and on distal
half, but not dense black, as in L. nigripinnis ; caudal broadly margined with black in varying degrees;

BULLETIN OF THE BUREAU OF FISHERIES.

pectorals and anal margined with fainter black, the latter less; ventrals usually pale, but not always.

This species is exceedingly close to Leucichthys nigripinnis , from which it differs by a somewhat
shorter snout, fewer gillrakers (18+33 in our specimen of L. nigripinnis ) and the less pronounced black
of the fins. In the measurements given by Evermann & Smith in the Report of the U. S. Commission
of Fish and Fisheries for 1894, page 318, the gillrakers for 17 specimens of L. nigripinnis of Lake Michi-
gan ranged from 16+30 to 19+34, whereas in our specimens (10 in number) of L. cyanopterus the
range is from 13+24 to 14 + 27. From L. zenithicus, to which it is almost as closely related as to L.
nigripinnis , it differs in the shorter maxillary, smaller mouth and deeper body.

The most marked differences are in the length of the maxillary, which in L. zenithicus ranges from
o. 10 to o. 1 1 of the body length, while in L. cyanopterus it is only 0.083 to 0.095, and in the greater depth
of body, the former ranging between 0.21 and 0.245 (with one specimen 0.26), while the latter varied from
0.245 to 0.28. All our specimens of L. cyanopterus were taken at Marquette, whence they were sent us
by Mr. August J. Anderson, a prominent fish dealer at Marquette. Four specimens of L. zenithicus
came from Marquette and 6 from near Duluth. The length of our specimens of L. cyanopterus is in
every case greater than that of any specimen of L. zenithicus. In quality of flesh there is a marked
difference, the L. cyanopterus taken at Marquette being very fat with thick abdominal walls, w+ile
L. zenithicus is generally lean and with thin abdominal walls. The greater depth of L. cyanopterus
may be due to accumulations of fat.

Other specimens are from Duluth and from off Knife River, at the head of Lake Superior. The
species abounds in the deep waters of the lake, its value exceeding that of the other deep-water species.
A large specimen apparently belonging to L. cyanopterus was found in the Toronto market. Its fins
were almost without dark markings. It must have come from Wiarton, on Georgian Bay. It is
very unlikely that any Lake Superior fish would be mixed with these.

Comparison of specimens 0} Leucichthys cyanopterus from Marquette , Lake Superior.

Specimen no. .

5242

5228

5246

5243

5248

5247

5244

5240

524s

5249

Length without cau-
dal mm . .

28s

29s

305

322

325

330

335

340

345

Dorsal rays

1 1

Anal rays

1 1

1 2

1 1

1 r

I I

Scales

8-79-7

8-78-7

8-86-7

8-85-7

8-82-7

8-87-7

8-81-8

8-76-7

8-83-8

8-82-7

Scales between occiput
and dorsal fin

Branchiostegal

14+27

13 +24

14+24

13 +24

14 +27

13 +25

14+26

Sex

Comparative measure-
ments:®

Head

0. 24

0. 265

0. 255

0. 245

0. 24

0. 25

0. 262

0. 25

0. 23

0. 245

Depth

■ 25

• 245

. 28

. 26

• 27

• 275

. 265

. 26

• 25

. 27

Caudal peduncle —
Length

. 10

• 115

. 12

. 1 r

• ii5

. 10

■ ns

. 12

• IIS

Depth

• 07s

• 07

. 08

. 085

. 08

• 075

.08

. 085

Eye

• 05

■ 05

• 054

■ 05

• 052

052

• 05

. 05

Snout

• 07

. 08

• 07

. 067

• 07

. 067

• 075

• 065

. 065

• 07

Maxillary from tip of
snout

• 095

. 087

. 083

• 095

• 09

. 09

Snout to occiput

- 17

. 18

• 17

• 165

• 175

. 18

. 165

. 173

Pectoral length

• 17

• 19

• 17

• 19

• 175

. 18

• 185

• 19

• 195

Ventral length

• 165

. 16

• 17

. 18

. 16

. 18

• 17

• I7S

. 16

Dorsal height

■ 15

• 155

■ IS

. 16

• 15

• 165

• 15

■ 15

• 14

. 14

Adipose length

. 065

- 07

. 07

• 07

. 06

. 065

• 075

. 062

• 07

Anal height

. 10

• 095

. 105

. 10

. IO

. 1 1

a Measurements in hundredths of body lengths unless otherwise specified.

Leucichthys hoyi (Gill). Cisco of Lake Michigan; Kiyi; Chub ; Mooneye Cisco. (PI. v.)

Argyrosomus hoyi Gill Ms., in Hoy, Trans. Wis. Ac. Sci., vol. i, 1872, p. 100, Lake Michigan off Racine; no descrip-
tion. Milner, Rept. U. S. Fish Comm, for 1872-73 (1874), p. 86; in part; no description. Jordan, Rept. Geol.
Surv. Ind. 1875, p. 5, Racine, Wis., specimen received from Doctor Hoy. Jordan & Evermann. Fishes of North
and Mid. Amer., pt. 1, p. 469, 1898, Racine and Kenosha. Evermann & Smith, Rept. U. S. Fish Comm. 1894,
p. 310, pi. 22 (1896), Lake Michigan.

Habitat: Lake Michigan, in deep water.

This beautiful cisco is very abundant in the deep waters of Lake Michigan and is an excellent
food fish, very delicate in flavor. We have examined specimens from Racine (Doctor Hoy’s type),

SALMONOID FISHES OF THE GREAT LAKES.

from Kenosha (here figured), and from Green Bay, off Escanada. Thus far it has not been certainly
recognized outside of Lake Michigan, the closely related L. zenithicus replacing it in Lake Superior
and probably in Lake Huron.

Description of Leucichthys hoyi from a cotype, a specimen 1 1 inches in length taken off Kenosha,
Lake Michigan, sent to Doctor Jordan by Doctor Hoy, no. 119x9, Stanford University collection:

Head about 4 in body length without caudal; body depth equal to head; length of caudal peduncle '
from last anal to first caudal rays 2.2 in head, depth of same 3.25; eye 4.5; snout 3.5; interorbital
space slightly less than snout; maxillary 2.5 in head; dorsal 10 (fully developed rays); anal 11; scales
7-72-7; branchiostegals 9; gillrakers 14+25 (gill-arch mutilated slightly, however).

Body somewhat elongated and compressed, yet not deep; dorsal and ventral outlines similar,
without nuchal hump or fullness; caudal peduncle long, somewhat compressed, and not deep; head
moderately large (not as long as in L. zenithicus or L. prognathus, but larger than in L. harengus or
L. artedi); snout rather long, blunt, because of almost vertical position of premaxillaries, which
approach those of a true Coregonus in position; jaws subequal, the lower slightly included; maxillaries
broad and long, extending slightly beyond vertical from center of pupil; eyes fairly large; distance
from snout to occiput long, 0.5 distance from occiput to dorsal fin insertion. Gillrakers numerous, their
length 0.5 eye diameter, slightly serrated on edges. Lateral line straight, scales moderate, smaller

Fig. 14. — Leucichthys hoyi (Gill). Cisco of Lake Michigan. (Drawn from a specimen 11.5 inches
long, collected in Lake Michigan at Kenosha, Wis. )

posteriorly. Dorsal fin inserted midway between snout and base of caudal fin, low, its longest ray
1.2 in head, its base 0.66 ray length, its margin truncate: adipose rather small; caudal widely forked ;
anal low, its longest ray 2.6 in head, its base slightly shorter or equal; pectorals and ventrals equal in
length, and equal to longest dorsal ray, the former not reaching quite half way to ventrals in specimen
at hand.

Color in spirits silvery, slightly darker above; cheeks silvery; fins colorless, save for slight black
on edge of dorsal and caudal.

Leucichthys zenithicus (Jordan & Evermann). Longjaw of Lake Superior.

Argyrosomus hoyi, Milner, Rept. U. S. Fish Comm. 1872-73 (1874), p. 86, Lake Superior at Outer Island, Wisconsin;
not of Gill, Hoy, or Jordan, and not original type.

Argyrosomus zenithicus Jordan & Evermann, Proc. U. S. Nat. Mus.,vol. xxxvi, March 3, 1909, p. 169, fig. 3, Lake
Superior, between Duluth and Isle Royale.

Habitat: Lake Superior, in deep water; possibly in other lakes.

Description of Leucichthys zenithicus, from n specimens, 8.5 to 12 inches in length, 4 from Mar-
quette, Lake Superior, and 7 from Duluth, Lake Superior:

Head 3.8 to 4 in length to base of caudal; depth 4 to 4.75 ; length of caudal peduncle from last anal ray
to first caudal 2.2 to 2.5 in head, depth about 3.5; eye, 4.6; snout, 3.5; interorbital space about equal
to snout; length of maxillary from tip of snout 2.6 in head; dorsal 10 or 11 (developed rays); anal 11
or 12; scales 8-77 to 83-7, between occiput and origin of dorsal, 32 to 34; branchiostegals 9; gillrakers
14 to 16+24 to 28.

BULLETIN OE THE BUREAU OF FISHERIES.

Body rather elongate, somewhat compressed, its width about 2.4 in length of head; depth greatest
cephalad of insertion of dorsal, seeming to taper posteriorly from somewhat larger head, but not always;
caudal peduncle moderately elongate and not deep, compressed; head rather large, larger than in L.
cyanopterus on average, but about same as L. prognathus, which is larger than usual ; snout proportion-
ately long; maxillaries long, extending almost to below center of pupil, gape large; lower jaw equal to
or longer than upper; distance from snout to occiput long, slightly more than half distance from occi-
put to dorsal. Eye large in proportion to the larger head; dorsal surface of head slightly arched and
convex between orbits. Lateral line -straight near center of body, scales moderate in size, loosely
attached. Dorsal inserted nearer base of caudal, high, its longest ray about 1.6 in head, its base 2.5, its
margin straight or slightly concave, the longest, first developed ray reaching beyond tip of last ray when
supine; adipose rather large, but variable; caudal deeply forked; anal short, its longest ray about 0.66
that of longest dorsal ray; ventrals long, reaching about 0.66 distance to anal; pectoral longer, reaching
more than halfway to ventrals, the fin length variable, merging into that of other closely related species.

Fig. 15. — Leucichtkys zeniihicus (Jordan & Bvermann). Lake Superior Longjaw. From the type.

Color in spirits silvery, darker above, no stripes clearly visible along rows of scales; dorsal and anal
broadly edged with dusky; other fins clear, save for occasional stipples of black. In life, clear metal-
lic blue above, silvery below.

Comparison 0} specimens of Leucichtliys zeniihicus.

Marquette, Lake Superior.

Duluth, Lake Superior.

S pecimen no . .

5238

5236

5241

5237

5215

5221

5219

5216

13084

5269

5257

Length without cau-
dal mm . .

230

247

252

253

205

255

235

240

275

240

250

Dorsal rays

1 1

Anal rays

1 1

Scales

8-80-7

8-78-7

8-77-7

8-83-7

Branchiostegals

Gillrakers

16+26

14 +28

14 +26

15 +26

14 +26

14+25

14+24

14+26

14+27

14+26

Sexual condition

Ripe 9

Ripe $

Ripe 9

Comparative measure-
ments: a

Head

0. 26

0. 25

O. 26

0. 25

0. 26

0. 255

0. 25

0. 26

O- 253

Depth

. 21

• 23

. 26

. 21

. 22

• 245

. 22

. 2 2

. 21

. 225

. 21

Caudal peduncle —
Length

. 10

• 105

. 11

. 105

. 1 1

. 10

• IIS

. II

Depth

• 07

• 075

. 075

• 075

.08

. 08

■ 075

• 075

■ 075

. 07

Eye

. 06

■ 055

• 055

. 06

• 055

. 058

• 055

Snout

• 075

• 07

■ 07s

• 07s

• 075

■ 07

• 075

. 08

Maxillary from tip of
snout

. 10

. 1 1

. I I

. IO

• 105

. 10

. 1 1

. 10

. 105

. II

■ 105

Snout to occiput

• 19

. 18

. 20

.185

. 18

. 185

.185

. 18

■ 19

Pectoral length

• 17

. 18

• 175

• 19

• 17

. 17

• 19

. 185

. 16

• 17

Ventral length

■ 155

• 17

. 18

. 17

• 17

• 15

.165

• 17

Dorsal height

• 15

. 16

• 165

. l6

• 17

. 16

. 165

. 16

■ IS

. 16

• 17

Anal height

. 10

. I I

• 09

. 10

• 09

. 10

. 1 1

• 095

. IO

a Measurements in hundredths of body lengths unless otherwise specified.

& From last of anal to first of caudal.

SALMONOID FISHES OF THE GREAT LAKES.

Subgenus ALLOSMUS Jordan.

Leucichthys manitoulinus Jordan & Evermann, new species. Manitoulin Tullibee.

Argyrosomus tullibee, Evermann & Smith, Rept. U. S. Fish Comm. 1894, p. 320, pi. 28; in part.

Type no. 64670, U. S. National Museum, a specimen 1 1 inches long, from Blind River, North Channel, Lake Huron;
coll., Dr. Seth E. Meek.

Habitat; North Channel of Lake Huron and probably lakes of Minnesota.

Head 3.89 in length without caudal; depth 3.4; depth of caudal peduncle 2.5 in head; eye 4.5;
snout 4; interorbital space 3.25; length of maxillary from tip of snout 2.75; dorsal 12; anal 13;
branchiostegals 7 or 8; scales 8-71-8; between occiput and dorsal 24; gillrakers 16+29.

Body somewhat over twice as deep as broad, comparatively elongate, more so than in Leucichthys
tullibee, symmetrically elliptical; dorsal contour of the head straight; snout rounded, tapering; lower
jaw slightly longer; maxillary extending to beneath anterior third of the eye, the supplementary bone
three times as long as broad ; teeth on tongue very minute, none on jaws, vomer, or palatines ; width of
opercle 4 in head, that of subopercle 7.5, measuring from anterior edge overlapped by opercle; gillrakers
0.87 diameter of eye in length ; lateral line straight, ascending a little at the anterior end ; scales moderate
in size, not deciduous, yet easily removed. Dorsal inserted midway between nares and base of caudal,
its height moderate, the longest ray 1.33 in head; adipose fin smaller than in the true tullibee, being

Fig. 16. — Leucichthys manitoulinus Jordan & Evermann, new species. Manitoulin tullibee.
(Drawn from specimen 11 inches long, collected at Blind River, North Channel of Lake
Huron.)

contained 4.25 to 6 in head, measured from insertion to free end; anal base one-half length of head and
equal to its longest ray-, ventral insertion not much posterior to that of dorsal, its longest ray 1.5 in
head, its scale contained 2.75 in its length; length of pectoral 1.33 in head.

Color in spirits, dark on dorsal surface of head and body above lateral line, silvery below, all fins
blackish but darker on the border; general hue suffused with smoky, as usual in fishes from waters
colored by “muskeeg” or the wash of sphagnum and of peaty substances.

This species is close to L. tullibee, from which it may be distinguished by the longer head, longer
snout, more slender body, larger eye, and longer and larger maxillary.

This description is based on three specimens, the type and two cotypes, at Stanford University,
all taken by Doctor Meek at Blind River on the north side of the North Channel of Lake Huron
Another specimen, smaller and more slender, is in the same collection. It is evidently one of the tulli-
bee group, but it is not identical with the tullibee of the northwestern lakes, differing in the more
elongate body and tail and in the smaller adipose fin.

All these characters and every other one shown by the species are approximations toward characters
shown by Leucichthys harcngus, the common lake herring of the same waters. We were told about the
Manitoulin Islands that the tullibee was occasionally taken, but we saw no specimens other than
these three.

bulletin of the bureau of fisheries.

Mr. Charles W. Triggs, a dealer in fish in Chicago, tells us that he recently had a consignment of
fish of this species sent from the North Channel to Chicago. There was no sale for them. The flesh
was poor and flavorless, almost worthless as food, in comparison with the other fishes of the Great
Lakes. This is said to be the only species of the tullibee type, or Allosomus, found in the Great Lakes,
and it is confined to the northern region of Lake Huron and perhaps of Lake Superior and the smaller
lakes of Minnesota

Leucichthys tullibee (Richardson). Tullibee; Tulipi.

Salmo ( Coregonus ) tullibee Richardson, Fauna Boreali-Amer., vol. ur, p. 201, 1836, Cumberland House, Pine Island
Lake (near Lake Winnipeg).

Coregonus tullibee, Gunther, Cat., vol. vi, p. 199, 1866, Albany River. Jordan & Gilbert, Synopsis, p. 301, 1883.

Argyrosomus tullibee, Evermann & Smith, Rept. U. S. Fish Comin. 1894, p. 320, pi. 28, 1896. Jordan & Evermann,
Fishes North and Mid. Amer., pt. 1, p. 473, 1898.

Habitat: Winnipeg basin, perhaps entering Lake Superior.

We have critically examined the following specimens of the tullibee type: One 13.75 inches long;
from Waubegon Lake at Oxdrift, Ontario; one 12.5 inches long, from Rainy Lake at Rainier, Minn.,
one 9 inches long, from Lake of the Woods at Warroad, Minn.; a specimen 18 inches long, presumably
from Minnesota, figured by Evermann & Smith in their whitefish paper; one 14 inches long, sent to

Fig. 17. — Leucichthys tullibee (, Richardson). Tullibee. (Drawn from specimen 12.5 inches long,
collected in Rainy Lake, Rainier, Minn.)

the Bureau of Fisheries by Dr. G. A. MacCallum of Dunnville, Ontario, presumably from Lake Simcoe;
one 14 inches long, from Oneida Lake, N. Y. ; two specimens 4.62 and 5.5 inches long, from Kettle
Falls, Minnesota.

Head 4 in body without caudal; depth 3; depth of caudal peduncle 2.5 in head, its length 3, as
measured from last ray of anal to first of caudal; eye 4; snout 4; interorbital space 1.25 in eye, 3.5 in
head; length of maxillary from tip of snout 3 ; dorsal 12; anal 12; scales in lateral line 67 to 72; between
dorsal fin and occiput 28; branchiostegals 9; gillrakers 16+34-

Body very deep, elliptical, its width a little less than half the depth; dorsal outline convex, curved
strongly upward from the snout; ventral outline nearly as convex as dorsal; head arched slightly
dorsally from snout to occiput, premaxillaries continuing the curve of the head; jaws nearly equal in
front but the lower contained in the upper; maxillaries extending to below the anterior edge of the
pupil, their supplementaries 2.5 times as long as wide and about half their width; scales large, rather
firm, lateral line nearly straight.

Dorsal truncate, inserted midway between the occiput and adipose fin, its highest ray 1.33 in head;
adipose fin large, its base equal to its height, measured from insertion to free tip, 3.5 in head; longest

SALMONOID FISHES OF THE GREAT LAKES. 33

anal ray 1.87 in head, anal outline concave; longest ventral and pectoral rays 1.33 in the head; ventral
scale 3.5 in ventral length; caudal widely but not deeply forked.

Color in spirits, light olive, silvery laterally, dark above; dorsal, anal, and caudal fins bordered
with dark; ventral and pectoral clear, slightly stippled with black.

The specimen from Rainy Lake differs in being much darker in coloration, the lower fins largely
black, a- few more scales (72) in the lateral line, slightly narrower opercle and subopercle, and slightly
larger adipose fin and ventral scale. The specimen from Warroad, Lake of the Woods, differs noticeably
in nothing but a darker coloration, more nearly approaching that from Rainy Lake, and the larger eye,
correlated with the smaller size.

We have taken as the basis of this description a tullibee from Waubegon Lake at Oxdrift, Ontario,
a tributary of Lake Winnipeg, as being nearest the type locality of the species, which is Pine
Island Lake, at Cumberland House, a tributary of the Saskatchewan which flows into Lake Winnipeg.
We present figures of specimens from Rainy Lake at Rainier and Lake of the Woods at Warroad.
In the specimens from the coffee-colored waters of Rainy Lake and Lake of the Woods the coloration
is very dark, as is usual with other species in the same locality. The only important differences are

Fig. 18. — Leucichthys tullibee (Richardson). Tullibee. (Drawn from a specimen 9 inches long,
collected in Lake of the Woods at Warroad, Minn.)

shown in the figures. The caudal peduncle is relatively thickest in the largest examples. The sub-
opercle in the Rainy Lake example is narrower than in the others. These are no doubt individual
differences.

Comparative measurements of all of the specimens are given in the following table :

Waubegon

Lake.

Rainy

Lake.

Lake of
the Woods.

Minne-

sota.

Kettle Falls.

Simcoe

Lake.

Oneida

Lake.

Length in inches . .

13. 75

11. 25

4- 625
14 or 15+28
14 or 15+28
3-95
4. 12
3- 5
4

5- 5

17+32 L
17+31 R
3- 65
3- 65
3-55
4

14 9
17+31
17+31
4. 6
3.25
5
5

14?
17+31 1-

17 + 29 R
4- 25
2. 83
5

4 +

Head

4
4
3

4. 18
2. 89
4 +
4- 25

3- 25

5 —

4- 25

4. 28
3- 2
5
4

Depth

Eye

Snout

48299° — Bull. 29 — 11 3

bulletin of the bureau of fisheries.

The tullibee or tulipi is the most abundant fish in the lakes tributary to Lake Winnipeg, its young
forming a large part of the food of the wall-eyed pike or yellow pike, Stizostedion vitreum. It is not
highly valued as food, its flesh being rather watery and tasteless. In the summer it is largely infested
with worms, which are found in the flesh of the back. In winter it is more esteemed.

The southern distribution of the tullibee is unknown. It occurs in certain small lakes of Minne-
sota and is reported in those of Wisconsin. Eastward Leucichthys artedi bisselli and Leucichthys erien-
sis, species not at all related, have been confounded with it. Doctor Bean records it from Onondaga
Lake, in New York. We have seen no specimens of the true tullibee from the Great Lakes, but we
are told that it occurs in Lake Superior and the North Channel of Lake Huron. Doubtless these
statements refer to L. manitoulinus. The “mongrel whitefish” of Lake Erie, once supposed by the
present writers to be the true tullibee, proves to be Leucichthys eriensis.

Comparison of species of Allosomus.

L. tullibee.

L. manitoulinus. Blind
River.

Oxdrift.

Lake of the
Woods.

Rainy

Lake.

S pecimen no . .

5229

5272

499

5273

5284

Length without caudal mm. .

330

210

270

245

205

Dorsal rays (fully developed)

Anal rays

Scales

8-67-8

9-67-9

9-72-8

8-71-8

8-77-8

Scales between occiput and dorsal fin

Branchiostegals

Gillrakers

Evisc.

16 + 28

, 16 + 29

l6 + 29

16+31

Comparative measurements: «

Head

0. 24

0. 25

0. 26

O. 25

0. 25

Depth

• 32

• 33

• 35

. 28

. 27

Caudal peduncle —

Length b

• 07

. 1 1

• 085

• 09

Depth

. 10

• 105

• us

. IO

. 10

Eye

. 06

. 065

. 06

Snout

■ 055

• 055

. 06

Interorbital space

• 07

• 075

.08

. 07

■ 075

Maxillary length from tip of snout

• 075

. 085

. 09

.08

Opercular breadth

• 07

. 06s

• 065

. 065

Subopercular breadth

. 04

• 03

. 025

• 03

Snout to occiput

• 17

. 18

Ventrals to pectorals

. 28

• 295

• 32

.31

• 3 1

Pectorals in pectoral-ventral distance

I- 55

1-5°

1 . 60

1. 66

1. 75

Pectoral length

. 18

. 20

• 19

• 17

Ventral length

. 18

. 20

• 17

Dorsal height

• 19

. 21

. 2 1

• 17

Adipose length

.08

. 04

. 055

Anal height

• 14

• 15

. 12

. 10

a Measurements in hundredths of body lengths to base of caudal unless otherwise specified.
b Length from anal to first caudal rays

SALMONOID FISHES OF THE GREAT LAKES.

Genus COREGONUS (Artedi) Linnaeus.

Subgenus COREGONUS.

Coregonus clupeaformis (Mitchill). Labrador Whitefish; Sault Whiiefish ; Lake Superior Whitefish;
Manitoba Whitefish ; Musquaw River Whitefish; Whiting of Lake Winnepesaukee; Shad of Lake
Champlain.

Salmo clupeaformis Mitchill, Amer. Monthly Mag., vol. n, 1818, p. 321, Falls of St. Mary, northern extremity of
Lake Huron; coll., Col. Samuel Hawkins, who called it “whitefish of the lakes.”

Coregonus clupeaformis, Jordan & Evermann, Proc. U. S. Nat. Mus., vol. xxxvi, 1909, p. 171, Sault Ste. Marie;
not Coregonus clupeiformis, Jordan & Evermann, Fishes North and Mid. Amer., pt. 1, p. 466, 1898, which is
chiefly based on Coregonus albus.

Salmo otsego a Clinton, Account of the Salmo olsego or the Otsego basse, 1822, p. 1, with plate, Otsego Lake.

Coregonus labradoricus Richardson, Fauna Bor. -Amer., vol. 111, p. 206, 1836, Musquaw River, Labrador, and of
many subsequent authors.

Salmo ( Coregonus ) sapidissimus Agassiz, Lake Superior, p. 344, 1850, Lake Champlain (type), after Zadock
Thompson ; Lake Superior.

Coregonus latior Agassiz, Lake Superior, p. 348, 1850, Lake Superior.

Coregonus neohantoniensis Prescott, Amer. Journ. Sci. Arts, vol. xi, 1851, p. 343; Lake Winnepesaukee, New
Hampshire.

? Coregonus richardsonii Gunther, Cat. Fish., vol. vi, p. 185, 1866, Arctic North America; locality unknown.

This species is the common whitefish of all the Great Lakes, Lake Erie excepted. It is also found
in many of the smaller lakes tributary to these. The Otsego whitefish ( Salmo otsego Clinton) is appar-
ently identical with this species, as is also the whiting of Lake Winnepesaukee.

Fig. 19. — Coregonus clupeaformis (Mitchill). Labrador whitefish. (Drawn from a specimen 21
inches long, collected at Rainy Lake, Rainier, Minn.)

This whitefish is generally recognizable by the compressed elliptical form, rather pointed snout, the
absence of a hump at the nape except in very large examples, and by the presence of a dusky shade on
the back, forming more or less distinct streaks along the rows of scales. It varies much in size, being

a This description is accredited by authors to the Medical & Philosophical Register, 1844, vol. 111, p. 188. The correct
title of this publication is “Annals of Medicine, Natural History, Agriculture and Arts, in four volumes, by J. W. Francis
& D. Harack, published in 1814”. The description and figure appear in a printed “Account of the Salmo otsego , or the
Otsego basse in a letter to John W. Francis, M. D., professor of obstetrics and the diseases of women and children in
the University of New York, by De Witt Clinton, LL. D., governor of the state of New York; published by C. T. Winkle,
101 Greenwich street, 1822.”

According to Doctor Evermann, who has examined the copy in the Library of Congress, the printed matter is on pages
1, 3. 4, 5, and 6. Preceding the title page, p. 1, is a full-page cut of the fish described. Following the words “Otsego
basse” has been written in lead pencil “ Coregonus clupeiformis” . The cut, although crude, plainly shows Coregonus
clupeaformis. The form is elliptical, and the back shows the dark streaks along the rows of scales usually characteristic
of that species.

bulletin of the bureau of fisheries.

mature at about 2 % pounds, and growing to the weight of 8 to 12 pounds in Lake Superior. These
very large whitefish are known as bowbacks. The species is one of the most valuable of all of our food
fishes. It is probably the only large whitefish native to the Great Lakes system, Lake Erie excepted.

In Jordan & Evermann’s Fishes of North and Middle America, the upper lakes were supposed
to be inhabited also by the Erie whitefish, and on this supposition the name clupeijormis was retained
for the latter, while the present species was called Coregonus labradoricus . There is very little differ-
ence between these two species, if species they really are. In general, Coregonus clupeajormis can be
told at once by its more elongate, more compressed and more symmetrical body, deepest at the dorsal
fin, and scarcely elevated at the nape, by its dark and streaked back, and by its longer pectorals, which
reach more than halfway to ventrals. The flesh of the Lake Erie fish is fatter and softer.

The whitefishes from the basin of Lake Winnipeg, or Manitoba whitefish, show the general traits
of Coregonus clupeajormis. In general, however, these are more robust, with larger head, deeper body,
and longer fins. The caudal peduncle is deeper than long (the gillrakers are mutilated in all our speci-
mens). Those from the dark or “muskeeg” water are unusually dark, with dark streaks above and
black fins. Those from the milky waters of Lake Winnipeg (about the mouth of the Red River of the
North) are all very pale, as pale as the whitefish of Lake Erie. As the water of Lake Erie is similarly
milky, discolored by muddy, clay-bottomed streams, it is a question whether this feature of coloration
is really a specific character. Perhaps Coregonus albus, as well as this Manitoba form, may be “onto-
genetic species,” or forms dependent on the food and the character of the water. Of the Manitoba
form of Coregonus clupeajormis we have examined hundreds of examples and have preserved examples
from Rainy Lake at Rainier, Lake of the Woods at Warroad, Lake Winnipeg at Fort Alexander, Lake
Playgreen, and Lake Waubegon at Oxdrift.

We figure the example from Rainy Lake.

The following description of Coregonus clupeajormis is taken from numerous specimens, mostly
from Lake Superior:

Head, 4.5 to 5 in body length to base of caudal; body depth 3.5 to 4; eye 4.5 to 5.5 in head; snout
3.5 to 4.5; maxillary to tip of snout 3 to 4; interorbital space 3 to 3.8; caudal peduncle length from last
rays of anal to first of caudal 1.8 to 2.5 in head, its least depth 2 to 2.5, but usually less than its length;
dorsal 10 to 12 (fully developed rays); anal 10 to 14; scales 72 to 86 (usually over 75), between occiput
and insertion of dorsal 30 to 34; branchiostegals 9 or 10; gillrakers 9 to 11 + 16 to 18 (25 to 28 in all)
on first gill-arch.

Body moderately elongate, increasing considerably in depth with age, deepest under dorsal; com-
pressed, its width about 2.5 in its depth; dorsal profile sometimes arched from occiput to insertion of
dorsal fin, sloping gradually to caudal peduncle, the latter deep, nearly as deep as long, sometimes
deeper than long, compressed strongly; head small, conic, square at tip, premaxillaries directed back-
ward so as to place mouth on lower side of projecting snout; lower jaw included, mandible reaching to
midway between pupil and hind margin of eye, about 2.6 in head; maxillary broad and short, extending
to anterior margin of eye, supplementaries broad, short, not as broad as long; distance from snout to
occiput about 2 in distance from occiput to insertion of dorsal; teeth on tongue only, very minute, barely
visible, except when dried.

Origin of dorsal about midway between snout and base of caudal; moderate in height, between 0.8
and the whole of the head length, almost always greater than distance from snout to occiput, its base
1.66 in head; adipose moderate or rather large, from insertion to free end contained about 2 to 3 in head;
pectorals and ventrals equal to longest dorsal rays in length (former reaching over halfway to vent in
forms from Lake of the Woods, Rainy Lake, and Lake Waubegon) ; anal low, its longest ray 1.66 in head,
its base 1.75 or 2. Lateral line straight, scales moderately large.

Color in spirits pale, darker above, always showing more or less distinct streaks along the rows of
scales; vertical, pectoral, and ventral fins usually colorless, save for dark margin of dorsal and caudal,
although others are sometimes dusky.

SALMONOID FISHES OF THE GREAT EAKES.

Comparison of Coregonus albus and C. clupeaformis.

C. albus. Lake Erie.

C. clupeaformis, Lake Ontario.

Specimen no . .

494

5255

5254

5253

4933

4914

4913

4936

4911

Body length mm . .

340

35S

315

290

275

26s

350

190

265

Dorsal rays

1 1

I I

Anal rays

1 2

1 1

I I

Scales

9-80-8

9-86-8

10-81-8

10-79-9

9-82-8

10—82-8

IO-80-8

i 0-8 i -8

Branchiostegals

Gillrakers

Comparative measurements:0

10+16

1 1 +16

9+18

10+18

10 +18

10 +19

10 +18

9+16

10+18

Head

0. 20

0. 225

0. 215

O. 21

0. 20

0. 22

0. 225

0. 21

Body depth

Caudal peduncle —

• 30

• 325

. 29

• 30

• 27

. 26

. 29

. 265

. 29

Length

• 105

. 10

• °8s

.08

. 09

. 10

- IO

• 125

• IIS

Depth

. 10

• 095

. 10

• 105

• 085

. 09

■ 09

Eye

• 045

. 04

■ 045

. 04

• 05

• 045

• 05

• 057

Snout

. 04

. 06

• 05

. 052

• 05

■ 055

• 05

. 05

Maxillary from tip of snout ....

■ 055

. 065

. 06

■ 065

. 06s

. 07

Distance snout to occiput

■ 14

• 15

. 16

• 15

■ IS

• IS

. 16

• 15

Pectoral length

. 18

• 19

. 18

• 163

• 17

• 19

• 165

. 18

Ventral length

. 18

. 20

. 18

. 165

• 17

■ 17

Dorsal height

■ 195

. 18

■ 185

. 18

• 175

• 17

. 18s

■ 17

Anal height

. 12

■ 13

• 13

. 12

. I I

. 12

■ US

. 115

“ Measurements in hundredths of body lengths unless otherwise specified.

Comparison of specimens of Coregonus clupeaformis.

Lake

Superior.

Lake Huron.

Lake

Michigan.

Lake of the
Woods.

Lake Waubegon.

Rainy

Lake.

Specimen no . .

5227

4927

13112

528

11918

5231

5259

Body length mm . .

283

37o

285

190

420

36s

270

445

Dorsal rays

1 2

1 1

Anal rays

1 1

Scales

10-84-8

10-79-8

10-78-9

10-79-8

10-70-8

10-74-9

Branchiostegals

Gillrakers

Comparative measure-
ments: °

20 +18

10 +16

8+17

10+16

Evisc.

Head

0. 20

0. 21

0. 225

0. 23

0. 225

O. 235

0. 23S

Body depth

Caudal peduncle —

• 25

. 26

• 25

• 37

. 29

• 32

Length

• 105

. 10

. 12

. 1 1

. 085

• 105

. 09

Depth

.08

. 09

. 085

. 11

. 1 1

. IO

Eye

. 04

• 05

■ 045

• 05

. 045

Snout

Maxillary from tip of

■ 05

. 06

• 05

. 06

• 055

. 06

■ 065

snout

Distance snout to occi-

• 055

. 06

• 05

• 065

■ 075

. 065

. 07

. 068

put

■ 15

• 155

• 15

• 17

. 16

. 167

. 165

. 16

Pectoral length

. 16

. 18

• 15

• 17

. 21

. 20

Ventral length

. 16

. 18

. 16

• 175

. 20

. 19

Dorsal height

. 16

. 20

. 16

. 195

. 21

. 2 1

. 20

• 17

Anal height

. 1 1

• 13

. 11

. 33

. 16

• 14

• 15

. 12

“Measurements in hundredths of body lengths unless otherwise specified.

Coregonus albus I,e Sueur. Lake Erie Whitefish; Common Whitefish. (PL vi.)

Coregonus albus Le Sueur, Jour. Ac. Nat. Sci. Phila., vol. I, 1818, p. 232, Lake Erie. Jordan & Evermann, Proc.

U. S. Nat. Mus., vol. xxxvi, 1909, p. 171, Lake Erie. And of many other authors.

Habitat: Take Erie and Lake St. Clair; introduced into other lakes.

This species is the common whitefish of Take Erie. It is very close to Coregotms clupeaformis,
the whitefish of the other lakes, differing only in form and color. Compared with the latter, the Erie
whitefish has a smaller head, higher nape, more angular form, and the color is almost pure olive-white,
without dark shades or dark stripes along the back. The flesh is softer, containing more fat. All
these differences may be correlated with the fact that Lake Erie is shallow and its southern shore is
fed by warm, shallow, muddy, or milky rivers. The difference shown by the wall-eyed pike of the
different lakes is supposed to rest on the same variation in environment. As no difference appears

bulletin of the bureau of fisheries.

in technical characters, we regard Coregonus a/bus as a doubtful species, its distinctions being perhaps
purely ontogenetic. On the other hand, it is claimed that the fry of the two can be readily separated.
Mr. Harry Marks, superintendent of the United States hatchery at Sault Ste. Marie, claims that the eggs
of Coregonus clupeaformis are larger and darker than those of the Lake Erie whitefish. The fry are
also livelier and are marked by two dark lines on the side, while those of C. albus are plain silvery.

The Lake Superior whitefish takes the hook readily, large numbers being taken every day in season
in the locks at Sault Ste. Marie by local anglers. Coregonus albus is not known to take the hook.

The eggs of the Lake Erie whitefish have been planted in all the other lakes, and we have
recognized specimens we call Coregonus albus from Lake Champlain, Lake Ontario, and Lake Superior
among the Apostle Islands. The close resemblance between the whitefish, fat, plump, and pale, from
the milky waters of Lake Winnipeg and those of Lake Erie has been noticed by many fish dealers.
We doubt if anyone could distinguish individual specimens from these two localities, although on the
average they are different. Possibly Coregonus albus is merely an “ontogenetic species,” its peculiari-
ties being due to the conditions of food and water in Lake Erie.

According to the figures issued by the Bureau of the Census, the total catch of whitefish in
United States waters of the Great Lakes for the calendar year 1908 was 7,482,800 pounds, valued at
$5°7>310- The following table shows the catch by states:

State.

Pounds.

Value.

Pennsylvania

451. 200

$36, 290

Ohio

732 , 200

60, 010

Michigan

4, 768, soo

339. 230

Indiana

5 r , 800

4. 990

Wisconsin

1, 274. 500

56,320

Minnesota

204, 600

10, 470

Total

7, 482, 800

507. 3io

Coregonus nelsoni Bean. Alaska Whitefish.

Coregonus nelsonii Bean, Proc. U. S. Nat. Mus., vol. vii, 1884, p. 48, Nulato, Alaska; type 29903 ; collector Edward
W. Nelson.

Habitat: Rivers and lakes of Alaska and Mackenzie River region.

This species resembles the Lake Erie whitefish, but has a smaller mouth and the flesh is said
to be dry and bony.

Subgenus PROSOPILTM Milner.

Numerous species of river whitefish occur in the United States. These belong to the subgenus
Prosopium, distinguished by the elongate form, the thick gillrakers. and the moderate or large
scales. In some of these the males have pearl organs or tubercles on the scales in spring. In some
the adipose fin is enormously developed. In some the snout in the male is much produced, and in
one the scales are much enlarged. Each of these types should perhaps stand as a distinct subgenus,
the typical species of each being quadrilateralis ( Prosopium ), william soni, coulter i and oregonius.

Coregonus quadrilateralis (Richardson). Menominee Whitefish; Pilotfish', Round. Whitefish; Shadwaiter.

(PI. VII.)

Coregonus quadrilateralis Richardson, Franklin’s Narrative, p. 714, pi. xxv, fig. 2, 1823, Fort Enterprise, British
America.

Coregonus nov-anglice Prescott, Am. Jour. Sci. Arts, vol. xi, 1851, p. 342, Lake Winnepesaukee N. H.

Habitat: Alaska and upper Great Lakes to New England, in lakes.

This species is common in Lake Superior and the northern parts of Lake Huron and Lake
Michigan. It may be known at once by its short head and elongate, little compressed body. It is
not highly valued as food, ranking even inferior to lake herrings in this regard, and agreeing with
them in size and form. It is destructive to the spawn of the whitefish.

The species is recorded by Evermann from Lake Bennett, Yukon Territory, where it was taken
by the writers in 1903. It is also recorded from various other localities on the Yukon and from
Wood River (Bristol Bay). As the species certainly does not occur in the Winnipeg basin, it may

SALMONOID FISHES OF THE GREAT LAKES.

be questioned whether this Yukon fish is not a distinct species of Prosopium separate from the ordinary
Coregonus quadrilateralis . Our specimens are from Mackinac, Cheboygan, Marquette, and Blind River.

Description of a specimen of Coregonus quadrilateralis 15.5 inches long from Blind River, North
Channel, Lake Huron:

Head 5.5 in body length to base of caudal; depth 4.5; eye 5 in head; snout 3.6; interorbita
breadth 3; maxillary from tip of snout somewhat longer than eye diameter; caudal peduncle length
1.28 in head, its depth one-half its length; dorsal 11 (fully developed rays); anal 12; scales 8-90-7,
between occiput and origin of dorsal 35; branchiostegals 8; gillrakers 6+10.

Body elongate, little compressed, more terete than in any other species of the genus, its greatest
depth and width in anterior portion of body, hence space from snout to insertion of dorsal more
strongly arched than remainder; caudal peduncle long, little compressed, half as deep as long; head
small, pointed; snout moderately short; post-orbital and sub-orbital bones broad; maxillary very short,
broad, not reaching eye; supplementary bone very narrow; mandible short, three in head, not
reaching posterior edge of pupil, included within upper jaw; dorsal contour arched somewhat,
although not greatly; distance*from snout to occiput 2.5 in distance from occiput to dorsal insertion.
Dorsal insertion nearer snout than base of caudal, its longest ray equal to distance from snout to
occiput, its base about 1.5 in head; adipose small; caudal short; pectorals short, somewhat longer

than dorsal rays, inserted low, reaching halfway to ventrals; ventrals very short, considerably more
so than pectorals; anal base somewhat more than 0.5 head, its longest ray 1.66 in head. Lateral line
straight, scales rather small.

Color in spirits, rather dark on sides and back, colorless ventrally; a line or streak of dark along
edges of longitudinal rows of scales, especially just below lateral line; fins pale, except for borders
of dorsal and caudal, which are dark

Coregonus kennicotti Milner. Kennicott’s IVhitefish.

Coregonus kennicotti Milner, in Jordan & Gilbert, Synopsis Fishes North Amer., p. 298, 1883, Fort Good Hope,
British America.

Habitat: Mackenzie River, Canada, Yukon River, and other streams of the Alaskan region
Recorded by Evermann from Lake Bennett, Alaska, v/here it is probably common.

Coregonus stanleyi Kendall. Stanley’s IVhitefish.

Coregonus stanleyi Kendall, Bull. U. S. Fish Comm., vol. xxii, 1902 (1904), p. 366, with figure, thoroughfare
between Mud and Cross lakes, Aroostook County, Me.

Habitat: Lakes of northern Maine.

This species, provided with pearly bodies on the scales in the breeding season, seems nearest to
the Rocky Mountain whitefish, Coregonus williamsoni.

BULLETIN OF THE BUREAU OF FISHERIES.

Fig. 21. — Leucichihys osmeriformis (H. M. Smith). Smelt. From the type, a specimen io inches long, taken in

Seneca Lake, New York.

Fig. 22. — Coregonus Coulteri Eigenmann & Eigenmann. Coulter’s Whitefish. From a specimen, 4 inches long, one of
the types, collected in Kicking Horse River, at Field, British Columbia.

SAlyMONOID FISHES OF THE GREAT LAKES.

Coregonus williamsoni Girard. Rocky Mountain Whitefish.

Coregonus williamsoni Girard, Proc. Ac. Nat. Sci. Phila. 1856, p. 136, Des Chutes River, Oregon.

Habitat: Rivers of the Sierra Nevada and west slope of the Rocky Mountains, from the Fraser
and the Columbia to the Truckee and other streams of the Lahontan basin of Nevada; abundant
especially in lakes of northern Idaho, western Montana, and Washington. One of the most delicious
of food fishes, and reaching a weight of 4 pounds.

Coregonus cismontanus Jordan. Y ellow stone Whitefish.

Coregonus williamsoni cismontanus Jordan, Bull. U. S. Fish Comm., vol. ix, 1889, p. 49, pi. 9, fig. 8, 9, Horsethief
Creek, Madison River, Montana: coll., E. R. Lucas.

Habitat: Streams of the Rocky Mountain region tributary to the upper Missouri.

It is very doubtful if this fish differs at all from Coregonus williamsoni which replaces it on the
west side of the Rock Mountains.

Fig. 23. — Coregonus oregonius Jordan & Snyder. Oregon V/hitefish. From the type.

Coregonus coulteri Eigenmann & Eigenmann. Coulter' s Whitefish.

Coregonus coulterii Eigenmann & Eigenmann, Amer. Nat., Nov., 1892, p. 961, Kicking Horse River at Field, British
Columbia.

Habitat: Headwaters of the Columbia.

A strongly marked species easily recognized by its large scales (60 to 63).

Coregonus eouesi Milner.

Coregonus couesii Milner, Rept. U. S. Fish Comm, for 1872-73 (1874), p. 88, Chief Mountain Lake, Montana;
coll., Elliott Coues.

Habitat : Headwaters of Saskatchewan River.

This is a strongly marked species, allied to Coregonus oregonius, and very improperly confounded
with Coregonus williamsoni by Jordan & Evermann.

Coregonus oregonius Jordan & Snyder. Chisel-mouth Jack; Oregon Whitefish.

Coregonus oregonius Jordan & Snyder, Proc. U. S. Nat. Mus., vol. xxxvi, 1909, p. 425, with fig., Mackenzie
River, Oregon.

Habitat: Lower Columbia River basin.

A well-marked species, agreeing with C. eouesi in the long snout, and further distinguished by
the very high adipose fin.

BULL. U. S. B. F. 1 909

PLATE II

LAKE HURON HERRING
Leucichthys sisco huronius (Jordan &. Evermann)

BULL. U. S.

PLATE III

BLOATER OF LAKE MICHIGAN
Leucichthys johannS (Wagner)

PLATE IV

Drawn by Charles B. Hudson BLACKFIN OF LAKE MICHIGAN

Leucichthys nigripinnis (Gill)

BULL. U. S. B. F. 1909

PLATE V

Drawn by Charles B. Hudson clsc0 Qp LA«E MICHIGAN

Leucichthys hoyi (Gill)

PLATE VI

Drawn by Charles B. Hudson COMMON WHITEFISH OF LAKE ERIE

Coregonus albus (LeSueur)

BULL. U. S. B. F. 1909

PLATE VII

Drawn by Charles B. Hudson MENOMINEE WHITEFISH; ROUND WH1TEFISH

Coregonus q u ad ri lateral i s (Richardson)

INFLUENCE OF THE EYES, EARS, AND OTHER
ALLIED SENSE ORGANS ON THE MOVEMENTS
OF THE DOGFISH, MUSTELUS CAMS (MITCHILL)

J-

By G. H. Parker, S. D.,

Professor of Zoology , Harvard University

INFLUENCE OF THE EYES, EARS, AND OTHER ALLIED SENSE
ORGANS ON THE MOVEMENTS OF THE DOGFISH, MUSTELUS
CANIS (MITCHILL).

By G. H. PARKER, S. D.,

Professor of Zoology, Harvard University.

The common occurrence of the smooth dogfish, Mustelus canis (Mitchill), in the
waters about Woods Hole, the success with which this fish can be kept in confinement,
and the ease with which it resists the adverse effects of operations led me to undertake
a study of its more important sensory reactions. This paper deals with the effects of
the following sense organs on the movements of the dogfish: Eyes, ears, lateral-line
organs, the ampullae of Eorenzini, and the organs of touch. The work was carried out
at the United States Fisheries Laboratory, Woods Hole, Mass.

CLASSES OF MOVEMENTS.

The more obvious external movements of the dogfish fall into four classes. The
first class consists of the movements of the eyeballs, either backward and forward, as
for instance when the fish is swimming, or rolling movements such as occur when the
animal is rotated on its long axis. The second class of movements are those of the false
eyelid or nictitating membrane, which can be made to rise from the ventral edge of the
orbit and thus cover the surface of the eyeball ordinarily exposed. The third class of
movements are the respiratory movements of the gill region. These vary much in rate
dependent upon the momentary state of the animal. In a large resting fish they vary
from about 35 to 45 movements per minute. The same fish when swimming slowly will
respire 50 to 55 times per minute. In vigorous swimming the rate is doubtless still more
rapid. The fourth class of movements are the locomotor movements which are carried
out in the main by the fins. The specific gravity of the dogfish is slightly greater than
that of sea water and when the fish ceases to swim it sinks to the bottom. As it has no
swim bladder, it is incapable of floating in the water as many teleosts do, and whenever
it is off the bottom it maintains its position necessarily by active swimming. In this
operation all the fins are concerned, but of these none is so important as the caudal fin.
If one dorsal fin or the anal fin is removed, the fish swims apparently as well as ever. If

BULLETIN of the bureau of fisheries.

all three fins, i. e., the two dorsal and the anal, are removed the efficiency in swimming
is somewhat reduced though not as much so as when the caudal fin alone is removed.
The removal of all the median fins leaves the fish still capable of forward locomotion
but only with excessive effort, largely because of the small amount of surface that can
be opposed to the water. The removal of the paired fins from one or both sides has
very little effect on the swimming of the fish, though its ability to turn accurately is
much reduced. The removal of all fins both median and lateral leaves the animal still
capable of wriggling through the water, though with a somewhat rolling motion. It
is probable that under normal conditions the lateral fins correct this roll. Of all the fins
the caudal is the one chiefly concerned with locomotion; the others serve mainly as keel-
like guides and rudders, though the median fins other than the caudal certainly
supplement this fin in the movements of swimming.

THE EYES.

When a normal dogfish is first put into even a large aquarium, it swims about with
much awkwardness, colliding with such objects as the dark walls and glass sides of the
aquarium and avoiding only the more conspicuous bodies, such as light-colored rocks,
etc. The impression given to the observer is that the dogfish has very poor vision, and
this opinion is current among many fishermen. After a few hours, however, such a
dogfish will adjust itself to its new quarters and will swim about with only an occasional
collision. That this condition is not dependent upon its acquaintance with the currents,
etc., in the aquarium is shown from the fact that if the dogfish is etherized and its optic
nerves are cut, it will swim slowly about bumping its nose continually against solid
objects precisely as a blinded animal might be expected to do. Nor does it ever recover
in any very marked degree from this state. It therefore seems clear that a normal
dogfish possesses fair vision and that it is capable of adjusting its responses to the stimuli
in its retinal fields with such precision that its locomotion is in large part guided by these
stimuli. The relation of the two eyes in these responses is clearly seen when only one
optic nerve is cut.. Under this condition the dogfish will still swim much as a normal
one does, though collisions will occasionally occur on its blinded side. Such a fish never
moves in circles, as many of the lower animals do, showing that the directive discrimina-
tion in one retinal field is of more importance in its locomotion than the mutual relation
of the two retinas.

Not only does a blinded dogfish fail to recognize the detailed illumination of its
surroundings, but its remaining sensory apparatus is apparently unstimulated by light.
If a beam of concentrated sunlight is thrown on any part of the skin of a blinded dog-
fish, no response is obtained, showing that the integumentary nerves of these fishes, unlike
those of the young lamprey (Parker, 1905 b ) and many amphibians, are not stimulated
by light.

Another feature to be observed in the blinded dogfish as compared with the normal
one is the region of its swimming. A normal dogfish will swim indiscriminately through
an aquarium, whereas a blinded one remains usually near the bottom and swims about in

EYES, EARS, AND OTHER SENSE ORGANS OF THE DOGFISH. 47

such a way as to be almost continually in contact with some solid surface, as though
relying on its sense of touch for its location.

If the nictitating membranes of a dogfish are drawn across the eyes and stitched to
the upper eyelids, the fish does not respond as a blinded fish does, but swims about in
the most brightly illuminated part of the aquarium. This is usually the top, but it may
be the bottom if light is admitted from low down on the sides. Such fishes are liable
to collide with solid bodies in their paths of motion and are doubtless reduced to the
condition of many lower animals in which the visual organs are not image-forming eyes
but mere direction eyes, i. e., the fishes are reactive to the presence or absence of light
and to the direction of a chief source, without, however, being able to respond to the
details of illumination in their surroundings. This condition is doubtless dependent
upon the fact that the intercepting nictitating membranes are at best only slightly
translucent and thus prevent the formation of efficient retinal images.

When a bright light is brought to the glass side of an aquarium otherwise dark,
normal dogfishes and those whose eyes are covered with the nictitating membranes will
gather near it. Very likely a submerged light in clear water could thus be made a lure
for dogfishes in the night. These reactions, however, cease in a generally illuminated
field such as surrounds the dogfish during daytime. As might be expected from what
has already been observed, blinded dogfishes show no response to a single light in an
otherwise dark field.

From these observations it is clear that the only part of the dogfish sensitive to light
is the eye and that the retinal image is an important factor in guiding the locomotion
of these fishes. In an otherwise unilluminated field dogfishes will swim toward a single
light, i. e., they are positively phototropic.

THE EARS.

The original function attributed to the vertebrate ear was of course that of hearing.
In 1828 Flourens recorded observations that led to the belief that the ear was also con-
cerned with equilibrium, and this opinion, though not without its opponents, has been
supported by Goltz, Mach, Breuer, and others. In 1891 Ewald advanced the view that
the ear likewise had to do with the maintenance of muscular tonus. These three func-
tions are the chief ones ascribed to the vertebrate ear. To what extent they are char-
acteristic of the ears of the dogfish will now be discussed.

In a previous paper (Parker, 1903), on hearing in fishes', I made the statement,
recently confirmed by Lafite-Dupont (1907), that the ears, lateral-line organ, and skin
of the dogfish were not open to stimulation by vibrations such as are produced by a
bass-viol string and transmitted to this fish through the water. But I also noted that
this fish was responsive to the same vibrations when it rested on a solid transmitting
base. It would seem from these observations that the smooth dogfish is at best only
slightly sensitive to material vibrations, and my subsequent work has shown the correct-
ness of this opinion. To test the question of hearing in the dogfish, I followed the plan
previously adopted for Fundulus (Parker, 1903), and experimented in the main with
three classes of fishes: (1) Normal individuals; (2) those with the eighth nerve cut but

bulletin of the bureau of fisheries.

with the surface of the skin normally sensitive, and (3) those with the ears intact but
with the surface of the skin rendered insensitive.

When a normal dogfish is placed in a large wooden aquarium, it at first swims about
in a disturbed and irregular manner. After half an hour or so it becomes so far accus-
tomed to its new quarters as to move about with apparent complacency. If, while the
dogfish is swimming through the water and is not in contact with the sides or bottom
of the aquarium, a fairly vigorous blow is struck with a mallet on the wooden wall of the
aquarium, the dogfish will almost invariably respond with a sudden jump forward.
This can be repeated many times provided that a few minutes intervene between the
trials. If the blow is not very vigorous the response may be only a slight waving of
the fins, best seen on the posterior edges of the pectorals.

To get some measure of this response, I suspended on a stout cord from the ceiling
of the room in which the experiments were conducted a large spherical iron weight so
that it formed the bob of a pendulum which, when at rest, just touched the middle of one
of the wooden sides of the aquarium. By drawing this iron bob away from its position
of rest and letting it swing squarely against the wooden side of the aquarium, a noise
was produced that would be louder or fainter depending upon the distance between the
bob and the aquarium side when the bob was liberated. The momentum with which
the blow given by the bob was struck was taken as a rough measure of the noise pro-
duced. As the whole apparatus was a simple pendulum, it was comparatively easy to
make the necessary calculations for a scale to be placed next the cord of the pendulum
to indicate the positions from which the bob must be liberated in order to generate
given momenta. The length of the pendulum was 260 centimeters and the weight of
its bob was 3,800 grams. The momenta used in the experiments and expressed in
centimeter-gram-second units were (1) 83,600, (2) 125,400, (3) 167,200, (4) 250,800, and
(5) 334,400, or, calling momentum (1) unity, they could be more conveniently designated
as 1, 1.5, 2, 3, and 4.

Normal dogfishes when swimming freely in the water of the aquarium occasionally
responded by pectoral fin movements to the sound generated by the bob of the pendulum
striking the wall of the aquarium with a momentum of 1, and invariably responded when
the momentum was 1.5. The range from 1 to 1.5 was therefore taken as the range of
minimum stimulus for a normal fish.

Six dogfishes, which had previously been tested to ascertain that they were normally
responsive, were now subjected to the operation for cutting the eighth nerve, and after
recovery they were again tried for their responsiveness. None reacted to the sounds
produced when the ball struck the side of the aquarium with a momentum of less than
3, and they responded invariably only when the momentum was 4.

At first sight this considerable reduction in the sensitiveness of the fish might be
taken to be a final answer to the question of the significance of the ear as a receptive
organ for sound, but it is possible that its real explanation lies in the reduced physio-
logical state of the animal as a result of so severe an operation as that of cutting the
eighth nerve. I therefore repeated these tests on several dogfish in which for other
purposes the optic nerves had recently been cut, and I found that notwithstanding the

EYES, EARS, AND OTHER SENSE ORGANS OF THE DOGFISH.

severity of the operation these fishes were as sensitive to sounds as normal fishes are.
I therefore believe that the loss of sensitiveness in dogfishes whose eighth nerve has
been cut is not due to the severity of the operation, but to the actual loss of the ear as
an effective sense organ.

As it has often been maintained that the responses of fishes to sounds depend upon
stimulation of the skin and not of the ears, I prepared another set of dogfishes in which
I endeavored to render the nerves of the whole integument insensitive to mechanical
stimulation. As in the case of Fundulus, so in the dogfish, I cut the fifth and seventh
nerves as well as the lateral-line nerves. I also pithed the animals by cutting off the
tail, plugging the caudal artery and vein with a ball of absorbent cotton so as to prevent
excessive bleeding, and inserting a wire into the spinal canal and twirling it as far forward
as the neck region so as to destroy the spinal cord. After recovery from these operations
the skin of the dogfish was found insensitive to mechanical stimuli except in the region
of the gills and pectoral fins. In my experiments on Fundulus this region was also of
necessity left sensitive to mechanical stimulation and might therefore serve as a recep-
tive surface for sound vibrations. In reporting my results on Fundulus I noted this
fact with regret, and it has been used as an argument against the validity of my results
by a recent critic, Korner (1905). It seemed to me therefore highly important to ascer-
tain whether this region of the skin played any important part in the reception of sound,
and for this purpose I attempted to render it insensitive without, however, interfering
with the nervous control of its underlying muscles.

To accomplish this end I endeavored to cut the dorsal roots of the spinal nerves
of this region, but my efforts were unsuccessful. I finally found in cocaine a means
of accomplishing my purpose. If a 2 per cent solution of cocaine is applied to a tactile
area on a dogfish’s skin, in from fifteen to twenty minutes the area becomes somewhat
mottled and loses its sensitiveness. I therefore placed, on a frame in the open air,
a dogfish in which the appropriate nerves had been cut, and after having started a
current of sea water through its mouth and gills for respiration I covered the remaining
sensitive part of its skin in absorbent cotton soaked in 2 per cent cocaine. Before
the application of the cocaine the dogfish responded by movements of the pectoral
fins to mechanical stimuli applied to these fins, but after a quarter of an hour these
responses ceased. After half an hour’s treatment the dogfish was taken from the
frame and suspended by its anterior dorsal fin in the sea water of the wooden
aquarium and subjected to sound stimuli. The animal occasionally responded by
movements of the pectoral fins to the sound produced when the bob of the
pendulum hit the side of the aquarium with a momentum of 1 and it invariably
reacted when the momentum was 1.5 or more; in other words, the animal, so far
as its responses to sound were concerned, differed in no essential respect from a
normal dogfish. Three other dogfish were tested in like manner and gave similar
results. I therefore conclude that the skin of a dogfish is not essential to its response
to sound.

To check these conditions in relation to the ear, two of the four dogfishes with
insensitive skins were subjected to the further operation of having their eighth nerves

48299° — Bull. 29 — 11 4

BULLETIN OF THE BUREAU OF FISHERIES.

cut. On testing these with sounds before the effects of the cocaine had disappeared
they were found not to respond to any sounds produced by the pendulum apparatus.
It therefore seems clear that the relatively slight response that the smooth dogfish
shows to sounds is mainly dependent upon the ear and that this fish, like Fundulus
(Parker, 1903), Carassius (Bigelow, 1904), and Cynoscion (Parker, 1910), may be said
to hear.

Having ascertained that the smooth dogfish is capable of hearing, I next endeavored
to determine what part of its ear is concerned with this function. The deep seat of
this organ and its relatively small size made my task so difficult that I was at last obliged
to abandon it, but one set of experiments in this direction are not without value. Fol-
lowing the directions given by Lyon (1900) for cutting cranial nerves, I found that
the sacculus of the ear of the dogfish was accessible for operative purposes through
the roof of the mouth and that this organ could be exposed in favorable cases without
causing bleeding. I made this exposure in seven dogfishes with the intention of opening
the sacculus and washing out its otolith with a fine current of sea water. In four cases
the operation was successful on both sides. These four dogfishes were given time
to recuperate and then were tested. All were strong and vigorous in their swimming
and, contrary to what would be expected from the statement made by Kreidl (1892),
they were absolutely indistinguishable from normal individuals in their equilibrium.
In their reactions to sounds produced by the pendulum apparatus they resembled
fishes in which the eighth nerves had been cut in that they were responsive only to
sounds made by a blow of the bob with a momentum of 3 or more.

Objections might be raised to these results, at least so far as equilibrium is concerned,
because the animals tested had had both otoliths removed, and in fact Loeb (1891 a) has
already declared that when only one otolith is taken out the animals show disturbed
equilibrium in that they swim with the operated side low. I removed a single otolith
from each of three dogfishes, but though I kept them under observation several days I
was never able to make out any characteristic irregularity in their equilibrium. These
results show that the large friable otoliths of the dogfish’s ears, like those of Siredon
and the frog (Laudenbach, 1899) and Cynoscion (Parker, 1908), are not essential to
equilibrium, but are, as in the case of Cynoscion at least, concerned with hearing.

That the ears of the dogfish have to do with equilibrium is so well attested by
previous investigators that this aspect of the subject calls for no special reconsideration.
After having had their eighth nerves cut, some smooth dogfishes will acquire the ability
to swim slowly in normal equilibrium — a condition which, as experiments have shown,
is certainly in part dependent upon the eye and perhaps in part upon the sense of touch;
but these animals when made to swim with ordinary rapidity lose equilibrium and pre-
sent a condition of irregular locomotion such as characterizes the majority of operated
animals at all times.

Possibly exceptional cases of this kind influenced Sewell (1884) and Steiner (1886,
1888) in their opinion that the ear of the dogfish was not concerned with equilibrium — an
opinion that has been set at naught by the more recent work of Loeb (1891 b), Kreidl
(1892), Lee (1892, 1893, 1894, 1898), Bethe (1899), Gaglio (1902), and Quix (1903).

EYES, EARS, AND OTHER SENSE ORGANS OF THE DOGFISH.

Although some of these investigators differ among themselves as to the details of their
conclusions, they all agree in ascribing a function of equilibration to the ear, and this
conclusion is abundantly borne out by my own observations. If both eighth nerves of a
smooth dogfish are cut, the animal becomes profoundly disturbed in equilibrium. It
usually swims in irregular spirals and will rest on the bottom in any position, dorsal or
ventral side up. When only one nerve is cut, the disturbance is much less pronounced.
After such an operation a dogfish will often swim and rest in the usual position and be
almost indistinguishable from a normal individual. If such animals are made to swim
rapidly, however, they usually show much unsteadiness and may even lose equilibrium.
A comparison of dogfishes in which one nerve has been cut with those in which both
have been severed makes it perfectly evident that the loss of one ear can be largely
compensated for by the other and that it is only after the loss of both ears that profound
disturbance of equilibrium can be looked for with certainty. These conditions are so
uniform and clear that the conclusion is fully justified that the ear of the dogfish is a
receptive organ from which emanate impulses that influence its locomotor mechanism
so far as to retain the equilibrium of a body that is naturally in a somewhat unstable
state.

A dogfish in which one of the eighth nerves has been cut is slightly weaker after the
operation than before it, and one in which both eighth nerves have been cut is invariably
very much weaker than it was previously. These differences are very noticeable in
handling the fishes, and they are characteristic of operations involving the eighth nerves.
Where, for instance, the second nerves have been cut, this diminution in muscle tonus
does not occur. It is, as Ewald (1892) has pointed out, a distinguishing feature of the
eighth nerve.

From these various observations and experiments on the ears of the smooth dogfish,
I conclude that these organs, like the ears of the higher vertebrates, are concerned with
hearing, equilibrium (Flourens), and muscular tonus (Ewald), and that the otoliths are
not essential to equilibrium, but are in some way concerned with hearing.

THE ORGANS OF THE LATERAL LINE.

As I have elsewhere shown (Parker, 1905 a), the lateral-line organs of the smooth
dogfish can be stimulated by material vibrations of low frequency. This stimulation
gives rise to movement of the fins, especially of the caudal fin, and to actual locomotion
in which the fish swims, where possible, downward into deeper water. Lee (1898) has
maintained on the basis of the movements of the fins as a result of the direct stimulation
of the lateral-line nerves that the lateral-line organs are concerned with equilibrium and
that in this respect they are closely related to the ear. I have repeated Lee’s experi-
ments so far as possible, but with rather different conclusions.

Lee states that if the lateral-line nerve is cut near its anterior end and stimulated
centrally, perfectly coordinated, definite movements of the fins occur. Thus if the left
lateral-line nerve is stimulated, the dorsal fins and caudal fin move to the right, the
right pectoral and pelvic fins move downward and the left upward. It is true that if

BULLETIN of the bureau of FISHERIES.

the lateral nerve is exposed and directly stimulated electrically precisely these move-
ments occur. They also occur if the lateral line on the surface of the body is stimulated
electrically. But none of these movements take place if previous to the stimulation of
the regions mentioned the spinal cord is destroyed. If the spinal cord of the dogfish
is destroyed from the tail to the neck region and the animal allowed to recover, no
amount of stimulation of the lateral line or its nerve in the region in which the cord has
been destroyed will, in my experience, call forth the fin movements described by Lee;
but if the lateral-line nerve is cut anteriorly these movements may be induced by
stimulating any spot along the appropriate side of the body, provided the stimulus is
applied anterior to the pelvic fins. Thus the responses described by Lee depend on a
stimulation of spinal nerves, not of lateral-line nerves. As Lee nowhere states that he
took steps in his experiments to eliminate the spinal nerves, I suspect that he mistook
reactions dependent upon these nerves for true lateral-line reactions. Thus the evi-
dence that he has brought forward for the equilibrium function of the lateral-line organs
falls to the ground.

Although the lateral-line organs, in my opinion, do not influence the fin movements
in the way that Lee believed, they are capable of effecting important responses. If the
skin of a dogfish whose spinal cord has been destroyed is pressed upon above or below
the lateral line, no reaction occurs; if, however, the pressure is brought to bear on the
lateral line itself, there is a considerable slowing in the respiratory rate or even a tem-
porary cessation of movement. This respiratory response can also be obtained when a
current of water is played on the lateral line, but it disappears permanently on cutting
the lateral-line nerve. With the lateral-line system intact it is, however, so invariable
in its occurrence that I believe that pressure may be regarded as one of the normal
means of stimulating this system. This view has already been advanced by Fuchs
(1894) as a result of his experiments on Raja.

The influence which the lateral-line organs of the dogfish have on its respiratory
rate is not limited to the side stimulated. A stimulus applied either to the right lateral
line or to the left one will effect a change in the whole respiratory mechanism.

The experiments thus far carried out show that the lateral-line organs of the dogfish
are stimulated by vibrations of low frequency and by simple pressure, both mechanical
forms of stimuli, and that these organs can influence the respiratory rate and the loco-
motion of the animal, but not in a way especially concerned with equilibrium.

the ampullae of lorenzini.

The head of the dogfish is marked with symmetrically placed clusters of minute
pores which are often mistaken for lateral-line pores. Each of these pores opens into
a long, narrow tube which makes its way below the skin and ends in a bulb-like enlarge-
ment. These are the ampullae of Lorenzini. They have long been suspected of being
related to the lateral-line organs, an opinion that is supported by their innervation.
So far as I am aware, no experimental evidence has thus far been obtained concerning
their function. As the region in which they occur is covered with a skin filled with

EYES, EARS, AND OTHER SENSE ORGANS OF THE DOGFISH.

tactile organs and penetrated by certain parts of the lateral-line system, it was necessary
first of all to eliminate these sense organs before conclusive experiments could be made
on the underlying ampullae. To effect this elimination, I painted the skin over a given
patch of ampullae with a 2 per cent solution of cocaine, hoping thereby to destroy the
receptiveness of the superficial tactile and lateral-line organs and leave that of the deep-
seated ampullae. After half an hour I tried various stimuli on this surface and I found
that pressure upon this spot was accompanied by a momentary slowing or cessation
of the respiratory movements. As I had also obtained this reaction from the lateral-
line organs and as these organs were possibly involved here, I abandoned this method of
procedure for another. This consisted in dissecting off the skin over a patch of ampullae
and thus removing the tactile and lateral-line endings completely. If, now, into the
mass of ampullae thus exposed, a blunt glass rod is gently pressed, the same partial or
complete respiratory inhibition takes place as was seen in the earlier experiment. As
this ceased on cutting the bundle of fine nerves that supplied the cluster of ampullae,
I conclude that pressure is a normal stimulus for the ampullae of Torenzini, and that
these organs are in truth closely related to lateral-line organs.

THE ORGANS OF TOUCH.

The whole outer surface of a smooth dogfish, like that of many higher vertebrates,
is open to stimulation from a deforming pressure, i. e., it is sensitive to touch. As a
result of this stimulation no alteration in the respiratory rate has been observed, but
movements of the nictitating membrane and fins have been called forth. The fin
movements often appear in coordinated groups such as would result in normal loco-
motion. Wherever tactile stimulation occurs, electrical stimulation is also usually
effective, with this difference, however, that the electrical stimulation may call forth a
much more vigorous response than the purely tactile does.

The surface of the dogfish’s body may be divided into some five tactile regions char-
acterized mainly by the responses that result from their stimulation. The first of these
regions is the part of the head anterior to the hindermost limits of the orbit. So far as
the fins are concerned tactile stimulation of this region results in only slight irregular
movements. When the stimulus is applied to a considerable stretch in front of the eyes,
or above or below them, or to a very restricted area behind them, quick closing move-
ments of the nictitating membrane occur. These movements, which are the really
characteristic ones of this region, are strictly homolateral in that mechanical stimulation
of the appropriate region on one side of the head never calls forth movements in the
nictitating membrane of the opposite side, but only in that of its own side. Since they
originate from a stimulus that in most cases is anterior to the eye and result in a closure
of the nictitating membrane, they may be regarded as primarily concerned with the
protection of the corneal surface of the eye-ball. Strange to say, they do not occur with
anything like the certainty when the cornea is touched as when the adjacent skin is
stimulated. This protective winking movement can be called out so far as I am aware
only by mechanical stimulation; the nictitating membrane is not moved when intense

bulletin of the bureau of fisheries.

sunlight is thrown into the eye or the surface of the cornea is bathed with even so stimu-
lating a solution as normal sulphuric acid. The protection apparently is only against
mechanical injury.

The second general tactile region includes the whole surface of the fish from the
posterior edge of the orbits to the pelvic fins except the ventral surfaces of the pectoral
fins and the skin on the breast between these fins. The second region is bilaterally divided
and a stimulus applied to any part of one side may call forth a movement of the two dorsal
fins, the caudal fin, and the anal fin away from that side, an upward movement of the
pectoral and pelvic fins of the stimulated side, and a downward movement of those of the
opposite side, a group of coordinated movements already described by Lee (1898).
These movements are undoubtedly concerned with guiding the fish in swimming.

The third general tactile region extends from the pelvic fins to the end of the tail.
This region, like the preceding one, is bilaterally divided. The same fins that respond to
the stimulation of the second region also respond to stimuli applied to this region, but the
response is in the reverse direction. A stimulus applied to one side of this region calls
forth a movement of the median fins toward that side, a downward movement of the
paired fins of the same side, and an upward movement of those on the opposite side.
Comparing this condition with that of the second region, it is clear that the fin responses
produced by stimulating a given side in the second region agree with those called forth
by stimulating the opposite side of the third region. This diagonal relation is probably
significant in the swimming movements of the dogfish.

The fourth tactile region is the ventral surfaces of the pectoral fins and the breast
region. Mechanical stimuli applied to almost any part of these surfaces call forth a
fairly symmetrical ventral approximation of the pectoral fins. At times there is almost
an overlapping of the posterior median edges of the two fins, but never a scissors-like
movement, such as Sheldon (1909) has demonstrated by chemically stimulating the
breast region.

The fifth region is the ventral surfaces of the pelvic fins. When these surfaces are
stimulated a symmetrical movement of the pelvic fins toward the median plane takes
place, thus closing the cloaca. There is some correlation between the response of this
region and that of the fourth, though in the main the two regions are independent.

The movements of the fins produced from the fourth and fifth region partake of
the nature of protective movements in that they wipe surfaces or close apertures. They
probably have little to do with locomotion. The reactions initiated in the second and
third regions are chiefly locomotor and probably have little significance otherwise. In
this connection the movements of the posterior dorsal fin are significant. This fin moves
with extreme freedom and in such a way that its posterior finger-like tip is wiped over
the back of the animal on the side stimulated as though it were intended to remove
some offending body. If, however, a weak stimulus is applied to a point low down on
one side of the body, the fin thus made to move slightly to one side, and then a strong
stimulus is applied between the dorsal line and the fin, the fin instead of wiping back
over the newly stimulated part turns still further away from the dorsal line and vigor-
ously wipes a part of the skin to which no stimulus whatever has been applied. It is

Byes, bars, and other sense organs of the dogfish.

therefore evident that the direction of the movement of this fin is dependent upon the
stimulation of any part of a given side and is not related to particular spots on that side.
Hence the movement probably subserves a general function like swimming rather than
a special one like the protection of the surface.

Not only are these fin movements called forth by the obvious tactile stimulation
of given areas of skin, but, as Lyon (1900) first pointed out, they can be induced by
moving certain parts of the body. If the end of the tail of a dogfish is seized symmet-
rically and turned to a given side, the dorsal and anal fins bend toward that side as though
a tactile stimulus had been applied to that side in what has been called the third tactile
region. That this reaction is really dependent upon a mechanical stimulation of the
skin and not upon the activity of more deeply seated sense organs, is seen from the fact
that the reaction disappears when the skin of the tail is rendered insensitive by about
twenty minutes’ treatment with a 2 per cent solution of cocaine. Not only can these
correlated fin movements be called forth by turning the tail, 'out they can also be induced
by moving the head. If the head of a dogfish is taken hold of symmetrically and turned
toward a given side the median fins, particularly the anterior dorsal, turn toward that
side. Thus the tactile surfaces of the dogfish are most intimately concerned with the
correlated movements of this animal’s fins and in such a way that they are undoubtedly
significant factors in the animal’s locomotion.

CONCLUSIONS.

The eyes of the smooth dogfish are the only receptive organs for light possessed by this
animal. The dogfish reacts with sufficient accuracy to the details of its retinal images
to show that it has moderately sharp vision. When the sharpness of its vision is greatly
reduced, it becomes simply positively phototropic.

The ears of the dogfish are organs of hearing and are concerned with equilibrium and
muscular tonus. The removal of their otoliths interferes with hearing but not with
their two other functions.

The lateral-line organs are stimulated by vibrations of low frequency and by
pressure. They are relatively insignificant as organs for the control of equilibrium.

The ampullae of Lorenzini are stimulated by pressure and are doubtless closely
related in origin and function to the lateral-line organs.

The whole integument of the dogfish is a receptive organ for mechanical stimuli.
From it arise impulses for the movement of the nictitating membrane, and for a com-
plicated system of correlated fin movements most of which are concerned with loco-
motion and equilibrium.

LIST OF REFERENCES.

Bethe, A.

1899. Die Locomotion des Haifisches (Scyllium) und ihre Beziehungen zu den einzelnen Gehirn-
theilen und zum Labyrinth. Archiv fur die gesammte Physiologie, bd. 76, heft 9-10,
p. 470-493.

Bigelow, H. B.

1904. The sense of hearing in the goldfish Carassius auratus L. American Naturalist, vol. 38.
no. 448, p. 275-284.

56 bulletin of the bureau of fisheries.

Ewald, J. R.

1892. Physiologische Untersuchungen ueber das Endorgan des Nervus octavus. Wiesbaden,
800, xiv+324 p., 4 taf., 1 photogr.

Fuchs, S.

1894. Ueber die Function der unter der Haut liegenden Canalsysteme bei den Selachiern. Archiv
fiir die gesammte Physiologie, bd. 59, p. 454-478, taf. 8.

Gaguo, G.

1902. Experiences sur l’anesthesie du labyrinthe de l’oreille chez les chiens de mer (Scyllium

catulus). Archives Italiennes de Biologie, t. 38, fasc. 3, p. 383-392.

Korner, O.

1905. Konnen die Fische horen ? Beitrage zur Ohrenheilkunde, Festschrift gewidmet August
Lucae, p. 93-127.

Kreidl, A.

1892. Weitere Beitrage zur Physiologie des Ohrlabyrinthes. Sitzungsbericht der K. Akademie der
Wissenschaften, Wien, Mathematisch-naturwissenscliaftliche Classe, bd. 101, abt 3,
p. 469-480.

LaEite-Dupont.

1907. Recherches sur l’audition des Poissons. Compte Rendus de la Society de Biologie, t. 63.
p. 710-71 1.

Laudenbach, J.

1899. Zur Otolithen-Frage. Archiv fiir die gesammte Physiologie, bd. 77, heft 5-6, p. 31 1-320.

LEE, F. S.

1892. Ueber den Gleichgewichtssinn. Centralblatt fiir Physiologie, bd. 6, no. 17, p. 508-512.

1893. A study of the sense of equilibrium in fishes. Part I. Journal of Physiology, vol. 15.no. 4,

p. 311-348.

1894. A study of the sense of equilibrium in fishes. Part II. Ibid., vol. 17, no. 3-4, p. 192-210.
1898. The functions of the ear and the lateral line in fishes. American Journal of Physiology,

vol. 1, no. 1, p. 128-144.

Loeb, J.

1891a. Ueber Geotropismus bei Thieren. Archiv fur die gesammte Physiologie, bd. 49, heft 3-4,
p. 175-189.

1891b. Ueber den Antheil des Hornerven an den nach Gehirnverletzung auftretenden Zwangs-
bewegungen, Zwangslagen und assoziirten Stellungsanderungen der Bulbi und Extremi-
taten. Ibid., bd. 50, heft 1-2, p. 66-83.

Lyon, E- P.

1900. Compensatory motions in fishes. American Journal of Physiology, vol. 4, no. 2, p. 77-82.
Parker, G. H.

1903. Hearing and allied senses in fishes. Bulletin United States Fish Commission, vol. xxii,

1902, p. 45-64, pi. 9.

1905a. The function of the lateral-line organs in fishes. Ibid., vol. xxiv, 1904, p. 183-207.

1905b. The stimulation of the integumentary nerves of fishes by light. American Journal of
Physiology, vol. 14, no. 5, p. 413-420.

1910. The structure and function of the ear of the squeteague. Bulletin United States Bureau
Fisheries, vol. xxvm, 1908, p. 1211-1224, pi. xxii.

Quix, F. IT.

1903. Experimenten over de Functie van het Labyrinth bij Haaien. Tijdschrift der nederlandsche
dierkundige Vereeniging, ser. 2, deel 7, afl. 1, p. 35-61.

Sewall, H.

1884. Experiments upon the ears of fishes with reference to the function of equilibration. Journal
of Physiology, vol. 4, no. 6, p. 339-349.

EYES, EARS, AND OTHER SENSE ORGANS OF THE DOGFISH.

Sheldon, R. E.

1909. The reactions of the dogfish to chemical stimuli. Journal of Comparative Neurology and
Psychology, vol. 19, no. 3, p. 273-31 1.

Steiner, I.

1886. Ueber das Centralnervensystem des Haifisches und des Amphioxus laneeolatus, und uber
die halbcirkelformigen Canale des Haifisches. Sitzungsberichte der koniglichen preus-
sischen Akademie der Wissenschaften, Berlin, jahrg. 1886, halbbd. 1, no. 26-28, p. 495-499.

1888. Die Functionen des Centralnervensystems und ihre Phylogenese. Zweite Abtheilung:
Die Fische. Braunschweig, 8vo., xii+127 p.

BARNACLES OF JAPAN AND BERING SEA

By Henry A. Pilsbry, Sc. D.

Curator Department of Mollusca, Academy of Natural Sciences of Philadelphia

Bull. U. S. B. F., 1909.

Plate VIII.

W. H. Dali and Helen Winchester, pinx.

A.HoenS Co Baltimore.

BARNACLES OF JAPAN AND BERING SEA.

By HENRY A PILSBRY, Sc. D.

Curator Department of Mollusca, Academy of Natural Sciences of Philadelphia .

The Cirripedia described herein were collected by the United States Fisheries
steamer Albatross during the expedition of 1906. With a single exception, all are from
Japanese waters and Bering Sea. The stations occupied are described in Bureau of
Fisheries Document No. 621.

Tittle has been published on the barnacles of the northwest Pacific and adjoining
seas; our knowledge of littoral and deep sea forms alike is scant. If the profusion of
other invertebrates has any significance, we may expect a rich and varied fauna of
Cirripedia off the Japanese east coast. Yet it must be admitted that the work of the
Challenger and that of the Albatross have given no evidence of unusual richness in this
cirripede fauna. An interesting feature brought out by the work of the Albatross is
that a number of species of Scalpellum and Pachylasma live upon the stalks and
pinnules of crinoids.

In Japan, acorn barnacles (Balanus sp.) are extensively used as manure. Bunches
of bamboo collectors, similar to those used for oyster spat, are planted in the tide flats
of Ariake Bay. After sixty to one hundred days they are taken up and the barnacles are
beaten off. The annual yield is 400,000 bushels, valued at 30,000 yen.®

Family SCALPFTLIDT.

Genus MITELLA Oken.

Mitella mitefla (Linnaeus).

1851. Pollicipes mitella Linnaeus, Darwin, Monograph on the Cirripedia, Lepadidae, p. 316.

Locality, Matsushima, on shore.

Genus SCALPELLUM Leach,

GROUP OP S. SCALPELLUM.

Scalpellum stearnsii Pilsbry. [PI. ix, fig. i (young).]

1907. S. stearnsii , Pilsbry, U. S. National Museum Bulletin No. 60 p. 14.

1907. 5. stearnsii , Hoek, Siboga Expeditie, Monographic xxxia, Cirripedia, p. 69, with var. gemina and robusla.

This species was originally described from the Pacific coast between the Bay of Tokyo and the
Inland Sea. The Albatross has taken specimens at the following stations:

Museum

number.

Station

number.

Locality.

Depth in
fathoms.

38663

4940

Kagoshima Gulf

IIS

38665

4941

117

38664

4942

11S

38677

4943

119

32875

3704

Seno Umi, off Hondo I

0 K. Mitsukuri, Bulletin of the Bureau of Fisheries, vol. xxiv, p. 287.

bulletin of the bureau of fisheries.

A specimen taken at Nagasaki by Lischke has been figured by Hoek. The same author has
described a variety robusta from the Malay Archipelago. This form has a broader capitulum and is
said to have a longer peduncle. In the latter character, at least, the Japanese form does not differ
from the Malaysian, as will be seen by the following measurements:

Station

number.

Length of
capitulum.

Breadth of
capitulum.

Length of
peduncle.

Number
of rings of
scales.

Remarks.

mm .

mm.

4942 -

Very plump.

4942

28.5

4940

4941

A dry specimen in the collection of the Academy of Natural Sciences of Philadelphia has a very
short peduncle; length of capitulum 44, width 28.5, length of peduncle, 20 mm. with 14 close scale
rings. In dry specimens the peduncle contracts a good deal, bringing the spaced scale rings close
together. The type originally figured by me was a dry specimen, which probably had originally a
peduncle fully as long as any of the variety robusta. It has about 26 rings of scales.

Scaipellum stearnsii var. gemma Hoek (= Scalpellum inerme Annandale) I regard as a distinct
species.

A young specimen (pi. ix, fig. 1) from station 4942 shows some suggestive features. The capitulum
is 8.5 mm. long, 4.5 wide. The umbo of the scutum is apical, and that of the Carina is nearly so, being
within 1 mm. of the apex, the total length of the carina being 7 mm. The inframedian latus is
comparatively much narrower than in adult individuals, and is somewhat contracted in the middle,
the umbo being situated below the middle near the rostral border. In shape this plate reminds one of
that of S. idioplax and its allies. The carinal latera project very little below the carina. No rostrum
is visible. The plates are closely juxtaposed, without the wide chitinous sutures of the adult stage.
These several characters, especially the positions of the umbones and the shape of the inframedian
latus, approximate to the structure of Arco scalpellum , and inasmuch as they probably represent
an ancestral condition, they indicate that the typical group of Scalpellum is a divergent phylum,
Arcoscalpellum being a more conservative group. The specimen figured is no. 38678 U. S. National
Museum.

Subgenus ARCOSCALPELLUM Hoek.

GROUP OF SCALPEELUM VELUTINUM.

This group was defined in Bulletin 60, U. S. National Museum, page 26, where the American species
are described. The following species belong here, all being deep-water forms:

Scalpellum velutinum Hoek.
-S', regium Wyville Thomson.
5. regium latidorsum Pilsbry.
5. regina Pilsbry.

5. darwini Hoek.

S. gig as Hoek.

5. giganteum Gravel.

S. moluccanum Hoek.

S. rubrum Hoek.

5. antarcticum Hoek.

5. sociabile Annandale.

5. alcockianum Annandale.
S. pedunculatum Hoek.

5. indicum Hoek.

S. hirsutum Hoek.

.S', hawaiiense Pilsbry

Scalpellum rubrum Hoek. [PI. vm, fig. 1, 2, 3, 4.]

1883. S. rubrum Hoek, Challenger Report, Zoology, vol. vm, p. 91, pi. 4, fig. 18.

This species was described from one specimen with the capitulum 5 mm. long, taken by the Chal-
lenger at station 204, near Luzon, in 100-115 fathoms. This specimen is described as “beautifully red
and white colored”, but without details as to the pattern. Its valves are “not covered by distinct
membrane,” and nothing is said of cuticular hairs. The internal organs were not examined.

BARNACLES OF JAPAN AND BERING SEA.

A series of ten specimens was taken by the Albatross at station 4934, Eastern Sea, off Kagoshima
Gulf, 30° 58' 30" N., i30°32/ E., 152 fathoms, rocky bottom. (No. 386S0 U. S. National Museum.)
These show that the Challenger example was a very young one. I have therefore thought it well to
describe the adult stage.

The oceludent margin of the scutum is slightly convex, that of the tergum a trifle concave. The
plates are crimson, passing into a dull yellowish tint. The pattern varies somewhat, but there is usually
a ray of the paler tint down the middle of each of the three larger plates, while the borders have crimson
rays. In some examples nearly the whole scutum is yellowish. The plates of the lower whorl are
generally crimson. The narrow sides and rounded ribs bordering the roof of the carina are milk white.
The flat, sunken roof has a crimson stripe bordering each lateral rib, the middle being pale. The plates
are covered with a very thin cuticle which is most minutely downy.

Fig. 1. — Scalpellum rubrum Hoek. A, 15th and 16th segments of outerramusof cirrusv; B, nth segment of inner ramus
of cirrus v; C, maxilla; D, terminal appendage; E, mandible.

The scutum and tergum each has a low median diagonal riblet running from umbo to the baso-
carinal angle. On both sides of this the surface is sculptured with low, irregular growth-wrinkles, and
extremely minute growth-striae; and weak fine radial striae may be seen in suitable lights. A low rib
runs along the scutal border of the upper latus, which is sculptured with growth-wrinkles and indistinct
radial striae, like the other plates.

The carina is very long, reaching upward beyond the upper fourth of the length of the carinal
border of the tergum; and its apex is thrust between the terga, w'hich diverge at the tips. On the roof
the fine growth-striae are broadly V-shaped.

The visible portion of the rostrum is small and triangular or oblong (pi. vm, fig. 2).

bulletin of the bureau of fisheries.

A dissected specimen shows that the true shape of the rostrum is very unlike its externally visible
face. It is wider than high, with concave upper and convex lower margin, as shown in figure 3, an inside
view of rostrum and rostral latera.

The inframedian latus is triangular, the base slightly longer than the sides.

The peduncle is short, with six rows of large erect scales, five to seven scales in each row. It is
rather copiously hairy. The scales are dull olive-yellowish, those of the carinal and adjacent rows
edged with crimson.

The measurements of three individuals follow:

Length of
capitulum.

Breadth of
capitulum.

Length of
carina.

Diameter of
carina.

Length of
peduncle.

Mm.

M m.

Aim.

16.0

9- 7

17. 0

3- 1

9. 0

17. 0

9. 2

17. 0

3-o

8. 0

17-0

10. 0

18.5

3-o

12.0

The mandible (fig. 1, E) has four teeth and a multispinose lower point. There is a very small
beard on the lower edge.

The maxilla (fig. 1, C) has a slightly sigmoid edge, closely spinose.

The first cirrus has very unequal rami of 8 and 1 1 segments, which are densely hairy. The other
cirri are of the usual slender form. The second cirrus has many spines on the inner faces of the cirri,
and five pairs on the anterior side. The third and fourth cirri have a row of about 3 small spines on the
inner face. The fifth cirrus has rami of about 27 segments, the median ones with four pairs of large and
one of small spines, and the usual tufts at the posterior sutures (fig. 1, A, 15th and 16th segments of
outer ramus cirrus v) ; besides these, the inner ramus has 1 to 3 small spines on the inner face of some of
the median segments (fig. 1 B, nth segment). The terminal appendages have 17 segments (fig. 1, D).

The penis is extremely long and slender, with some short, very sparsely scattered hairs.

GROUP OF SCALPELLUM ALBUM.

A group of Arcoscalpellum; rostral latera rather high; inframedian latus narrowly triangular with
apical umbo; carinal latus high, with incurved apical umbo. Scales of the peduncle well developed, in
few (5 or 6) regular longitudinal rows. Small forms, living so far as we know on the pinnules of crinoids.
The following species belong here :

a. Rostrum well developed; carina extending downward V-like between the carinal latera.

Scalpellum album Hoek, Malay Archipelago, 500 fathoms.

S. weltnerianum Pilsbry, ofF southern Japan.

5. pentacrinarum Pilsbry, off Havana, Cuba.

b. Rostrum minute or wanting; carinal latera enormously long, united in a suture below the carina

Scalpellum balanoides Hoek, 50 42' S., 1320 25' E., 126 fathoms.

S. gonionotum. Pilsbry, Goto Islands, Japan.

Scalpellum weltnerianum Pilsbry. [PI. ix, fig. 5, 6, 7.]

Type no. 32679 U. S. National Museum.

Type locality: Albatross Station 4918, 30° 22' N., 1290 08' 30" E., 361 fathoms, about 90 miles
WSW. of Kagoshima Bay, Japan; one specimen on a crinoid pinnule.

The capitulum is fully twice as long as wide; the occludent border is straight, the dorsal border
arched. The plates are white, with an extremely thin, not hairy, cuticle, and those of the upper whorl
are separated by distinct but rather narrow chitinous spaces which isolate the carina and upper latus
except at their bases. All of the plates are sculptured with radial striae or fine riblets, which are weaker
and worn near the apices; and there are some spaced impressed lines indicating growth periods.

BARNACLES OF JAPAN AND BERING SEA.

The scutum is narrow, with the beak reaching over the base of the tergum. The basal margin
makes a right angle with the occludent margin, and is less than half its length. The diagonal ridge is
acute in its lower part.

The tergum is about three times as long as wide, with straight occludent and basal margins. The
carinal margin is straight except near the lower angle, where it becomes convex. The apex of the carina
lies in the middle of the carinal margin. The surface of the plate is lightly concave near the occludent
margin.

T'he carina is regularly and strongly arched throughout, with rounded roof. In section it is U-shaped.
The sides are wide near the base, pass gradually into the roof and taper regularly toward the apex, near
which an extremely narrow intraparietal area is visible through the cuticle. The lines of growth descend
V-like on the roof.

The upper latus is quadrangular, more than twice as long as wide. The scutal border is much the
longest and is concave; tergal border straight, somewhat serrate; carinal border slightly convex; basal
border very oblique and straight. The lower angle of the plate is concealed under the apex of the
inframedian latus. The umbo is terminal above.

The visible part of the rostrum is lozenge-shaped or rather narrowly pointed-oval, with regularly
convex sides and a ridge down the middle.

The rostral latus is about as high as wide, with straight and equal scutal and lateral borders meeting
at an angle of about 6o°. The basal margin is very short, and the rostral margin is concave.

The inframedian latus is narrowly triangular, the height more than double the basal width. It
is longer than the adjacent edge of the rostral latus, and toward the apex it curves slightly toward the
carina.

The carinal latus is higher than wide, with the acute apical umbo curving scutad and situated at
the suture between carina and upper latus. The carinal border is longest, strongly arched; upper
border concave; the lateral margin is somewhat concave. The surface of the plate is divided by a
curved diagonal line from the apex to the baso-lateral angle separating the sunken lateral area from
the strongly convex carinal area. In carinal view, the carinal latera meet at the base, their carinal
edges forming a long V.

The peduncle tapers strongly toward the base. It is closely covered with strongly imbricating and
laterally interlocking subtriangular white scales, which under a high power are seen to be finely striated
from summit to base. The scales form six regular longitudinal rows, of fourteen scales each.

Length of the capitulum n mm.; greatest width 5 mm. Length of the carina 8.2 mm.; width
near the base 1.5 mm. Length of the peduncle about 4 mm.

A single example was taken. In order to preserve this entire, I was compelled to forego examination
of the internal organs. It is closely related to 5. album Hoek described from the Malay Archipelago
in 500 fathoms, but that species seems from the description and figure to be smoother, more compressed,
and larger. Hoek writes of .S. album: “surface smooth * * * when studied with the microscope

the beautiful striation of the valves distinctly appears”. In S. weltnerianum the costation is distinctly
visible to the naked eye. 5. -weltnerianum is also related, though rather distantly, to Scalpellum penta-
crinarum Pilsbry,0 a West Indian species also living on the pinnules of crinoids. The peculiar armor
of the peduncle is the same in the two species, which further agree in the structure of the carina and the
general shape of the other plates; but the sculpture and proportions of the individual plates are quite
diverse. The very sparsely scattered hairs mentioned in my preliminary description are, I am now
disposed to think, foreign growths.

This species is named in honor of Herr W. Weltner of the Museum der Naturkunde in Berlin, author
of several useful papers on cirripedes.

Scalpellum gonionotum Pilsbry. [PI. ix, fig. 2, 3, 4.]

Type no. 38678, U. S. National Museum.

Type locality: Albatross station 4901, 320 30' 10" N., 128° 34' 40" E., 10-20 miles southwest
of the Goto Islands.

®U. S. National Museum Bulletin no. 60, p. 55, fig. 20.
48299° — Bull. 29 — ir s

BULLETIN OF THE BUREAU OF FISHERIES.

The capitulum is narrow and long, widest near the middle, tapering toward both ends, with no
perceptible cuticle or pubescence. Occludent margin straight, carinal margin obtusely angular in the
middle. The plates are white, everywhere closely juxtaposed, with sculpture of rather widely spaced
grooves indicating former growth-periods.

The scutum is long, with straight, subparallel occludent and lateral margins; basal margin straight,
at a right angle with the occludent margin.

The tergum is longer and larger than the scutum, with slightly convex basal and carinal margins,
the apex erect.

Carina very short, nearly straight, with apical umbo at the upper fourth of the carinal margin of
the tergum. Roof flattened; sides rounded, narrow, of nearly equal width throughout. Upper latus
triangular, the sides and angles subequal.

Rostrum very narrow, separating the rostral latera in the upper half of their length.

Rostral latus somewhat wider than high, quadrangular, divided into triangular areas by a low
diagonal ridge.

The inframedian latus is triangular, the apex curving toward the occludent margin. The basal
width is about half the height.

The carinal latus is enormously lengthened, as long as the Carina. The two latera meet behind in
a straight suture, diverging only near the apices, which curve ventrad. The carinal outline of the plate
is convex; the lateral border is divided into two concave arcs, a point between them projecting toward
the occludent margin.

The peduncle tapers rapidly to the small base. It is densely covered with ivory-like scales
arranged in five regular longitudinal rows, of which one is carinal, two on each side lateral. The
carinal row has 14 scales, which are not so wide as those of the other rows. In the largest specimen a
few additional scales are interposed between the lateral rows near the base of the capitulum.

Length of the capitulum 7.3 mm.; breadth 3.5 mm. Length of the carina 3.5 mm.; length of the
peduncle 4.2 mm. A second specimen is slightly smaller; length of the capitulum 6 mm.

This curious little species is closely related to 5. balanoides Hoek, taken by the Challenger in
50 42' S., 1320 25' E., in 129 fathoms. A number of specimens were seated on a crinoid arm, none of
them so large as S. gonionotum, the capitulum being only 4.5 mm. long, peduncle with five rows of seven
scales each. S. balanoides has no rostrum; the dorsal margin is regularly curved, not hunchbacked like
S. gonionotum , and the inframedian latus is very much narrower. Moreover, the roof of the carina
is flat in S. gonionotum. The two species seem therefore to be quite distinct. The two specimens of
.S. gonionotum were detached when received, but from the shape of the impression near the base of
the peduncle, they were attached to some narrow object, probably a crinoid pinnule.

GROUP OP SCALPELLUM japonicum.

The species of this group have one or more longitudinal rows of spines on the segments of the
posterior cirri, besides the usual pairs on the anterior and along the posterior margins. The posterior
side is also minutely spiculose. The somewhat allied .S', imperjectum Pilsbry has similar segments.

This group seems to be rather richly developed off southeastern. Japan. The species are variable,
and many more forms probably await the dredge.

Scalpellum japonicum Hoek. [PI. x, fig. 1 to 5, 9.]

1SS3. Scalpellum japonicum Hoek, Challenger Report, vm, Cirripedia, p. 67.pl. 3, fig. 9, 10 (type locality, Chal-
lenger Station 235, lat. 340 7' N., long. 138° E., in 565 fathoms).

1907. Scalpellum japonicum metapleurum Pilsbry, Proc. Acad. Nat. Sci. Phila., 1907, p. 360 (type locality
Albatross station 4972).

This species was based upon a single example with the capitulum 13.5 mm. long, taken in the Pacific
off Japan south of the middle of Plondo Island in deep water.0 Since the published drawing does not
show clearly the shape of the calcified portion of the upper latus, I have given a view of the right side

a The shell upon which this barnacle is seated was thought by Hoek to be perhaps a species of Rissoa, but from its
size and shape, as shown in Hoek’s drawing, I think it may be a Balhybembix ( Turcicula ).

BARNACLES OF JAPAN AND BERING SEA.

(pi. x, fig. 9) from a camera lucida sketch of the type which I owe to the kindness of Mr. W. T. Col-
man, of the British Museum. These show the calcified area to be irregularly oblong, with subparallel
scutal and basal borders, and with two short subequal, straight facets opposed to the carina and the
carinal latus, respectively. The peduncle is described as 4.5 mm. long, with about 8 longitudinal rows
of 7 scales each. The two sides of the type are alike.

The Albatross took two specimens of Scalpellum at station 4972, south of Hondo, 330 25' 45” N.
1350 33' E., in 440 fathoms, which agree in the main with japonicum, but differ a little in shape of
the upper latus. These specimens may be referred to as no. 38684 and no. 38685.

No. 386S4 (pi. x, fig. 1, 2, 3) has a capitulum 17 mm. long, 9.5 wide, peduncle 5 mm. long. The
calcified portion of the upper latus on the right side (fig. 1) forms a quadrangular band transverse to the
length of the capitulum, with an oblong tongue projecting beyond the umbo. There is no calcified lobe
along the scutal margin, and it differs from the type of 5. japonicum in having no straight face opposed
to the carinal latus. On the left side, the upper latus has a slightly waved lower margin, approaching
in a slight degree to the condition in specimen no. 38685, and to typical S. japonicum. The other

Fig. 2. — Scalpellum japonicum. A, terminal appendage; B, maxilla; C, mandible; D, segments from both rami of cirrus v.

plates are substantially as in the type of 5. japonicum. The peduncle has 8 longitudinal rows of about
7 large scales each, therefore like that of S. japonicum. This is the specimen I called var. metapleurum,
which name will now become a synonym of japonicum.

Specimen no. 38685 measures, length of capitulum 15, width 9, length of peduncle 6 mm. On the
left side the upper latus is shaped substantially as in no. 38684, but on the right it is narrower, and
abruptly attenuated near the carinal end (pi. x, fig. 4). The rostrum is a trifle smaller (pi. x, fig. 5).
The scales of the peduncle are less numerous, only 4 or 5 in each longitudinal row. Both of the above
specimens are clothed with a very thin, finely pilose cuticle, which has been mainly ignored in the fig-
ures, in order to show the outlines of the calcified valves more clearly.

Specimen no. 38684 was opened. The mandible (fig. 2, C) has three acute points and a severi-
spined lower point. There are a few scattering hairs below, but elsewhere the borders are very
smooth, simple, and clear-cut.

The maxilla (fig. 2, B) has very few spines, a few hairs below but none on the upper margin.

The first cirrus has unequal rami of about 7 and 12 segments, but they are not distinct in my prepa-
ration. The second cirrus has subequal rami, is profusely bristly, with 6 or more pairs of large spines

bulletin of the bureau of fisheries.

on the anterior margin of each segment The fifth cirrus has branches of 33 and 27 segments. The
posterior edges are set with minute spines The outer branch has three pairs of large and one of small
spines along the anterior border. There are two or three very unequal spines posteriorly at each
suture, and one or two between the sutures. There is also a row of short spines along the inner face
of the ramus. The inner branch has longer segments, with more spines along the anterior border —
as many as 6 or 7 pairs. There are two rows along the inner face of the ramus (fig. 2, D, 12th segment
of inner ramus and 13th and 14th segments of outer ramus of cirrus v).

The terminal appendages (fig. 2, A) have 6 segments, with very few bristles except for a group of
long ones at the apex. Its length, not measuring the apical bristles, is 2.25 mm.

At Albatross station 4901, southwest of the Goto Islands, Eastern Sea, 139 fathoms, a minute
barnacle was taken, which I believe to be the young stage of S. japonicum or some closely related form.
It is figured on plate x, figures 6, 7, 8. The capitulum is 6.3 mm. long. The carina is separated from
the tergum and upper latus by a narrow chitinous space, the other plates being closely juxtaposed.
There is a narrow rostrum. The umbo of the inframedian latus is near the lower third. The carina
has a rather broad roof. The peduncle has rather large scales, sparse except on the dorsal side. If
mature this barnacle would be thought a member of the group of Scalpellum idioplax; but its characters
are just what one would expect in young of the 5. japonicum group. The specimen is no. 38688, U. S.
National Museum.

Scalpellum japonicum biramosum. New subspecies. [PI. xi, fig. 1, 2, 3.]

Type no. 38686, U. S. National Museum.

Type locality: Albatross station 4972, south of Hondo Island, Japan, 330 25' 45" N., 1350 33' E-,
440 fathoms.

This form was associated with the two specimens of 5. japonicum described above. It differs
from them in the following respects: The umbo of the carina is nearer the upper end of the plate.
The upper latus has a lobe extending down along the scutal border; this lobe is bifid on the right
(fig. 1), simple on the left side (fig. 2). The hour-glass-shaped inframedian latus is less excavated
along its upper border than in japonicum. The rostral latus is much higher. The rostrum is reduced
to a punctiform vestige. The peduncle has 10 longitudinal rows of about 7 scales each. Length of
capitulum 17.5 mm., width 9.3 mm., length of carina 17 mm., diameter at base 2 mm. Length of
peduncle 4 mm.

Whether this form will prove to be within the range of normal variation of 5. japonicum or not
remains to be determined by future collections.

Scalpellum molliculum. New species. [PI. xi, fig. 4, 5.]

Type no. 38687, U. S. National Museum.

Type locality: Albatross station 4967, south of Hondo Island, Japan, 330 25' 10" N., 1350 37' 20”
E-, in 244 fathoms.

A species allied to S. curiosum and 5. japonicum. The oblong capitulum is widest in the middle,
tapering toward both ends, the occludent and carinal margins about equally arched. The calcified
portions of the valves are white, the chitinous portions yellowish. The very thin cuticle is nowhere
hairy.

The scutum has an arcuate occludent margin, and a short projection at the tergo-lateral angle.
The baso-lateral margin is rounded.

The tergum is V-shaped, the occludent limb narrower and much shorter than the carinal.

The carina is regularly and strongly arcuate, with a flat roof and slightly projecting angles. The
sides are narrow, a little wider above; they meet above the umbo, which is removed a very short
distance from the upper end of the plate.

There is no externally visible rostrum.

The upper latus is triangular, the umbo quite near the apex. The carinal margin is very short, the
basal margin irregular.

BARNACLES OF JAPAN AND BERING SEA. 69

The rostral latus is oblong, the lateral margin longer than the rostral; upper and lower margins
subparallel.

The inframedian latus is fan-shaped, wide in the upper part, tapering from the middle to the very
narrow base, where the umbo is situated.

The carinal latus is triangular, the umbo projecting a little at the baso-carinal angle, there is a
short, straight face opposed to the upper latus and a long, slightly concave margin opposed to the
inframedian latus.

The peduncle is closely covered with rather small scales in about 15 rows of 12 to 15 scales each.
Some of the longitudinal rows do not reach to the base of the peduncle, the scales being somewhat
irregularly arranged in places.

Length of the capitulum, 19.5 mm.; width, 11 mm.; length of the carina, 19 mm.; diameter at
base, 3 mm.; length of the peduncle, 6.5 mm.

Fig. 3. — Scalpellum molliculum. A, basal segments of cirrus vi with terminal appendage; B, maxilla; C, 16th segment

of cirrus v; D, mandible.

The type specimen was dissected. The mandible is very similar to that of 5. japonicum, differing
only in being a little more slender, with fewer spines at the lower point (fig. 3, D).

The maxilla (fig. 3, B) is also like that of S. japonicum. As in that species, the upper spine stands
alone, then two great spines diverge from a common base.

The first cirrus has unequal rami of 8 and 1 1 segments. The later cirri have segments with four
pairs of large and one of minute spines at the anterior edge. They do not differ materially from those
of 5. japonicum (fig. 3, C, 16th segment of cirrus v).

The terminal appendages consist of 9 segments, the last 6 copiously spinose at the articulations.
The total length, exclusive of the terminal spines, is nearly 4 mm.

This species differs from 5. japonicum by the shapes of the upper, inframedian, and rostral latera,
and especially by the more numerous scales of the peduncle. The plates are also more fully calcified,

BULLETIN OF THE BUREAU OF FISHERIES.

although the specimen is larger. In 5. japonicum the larger specimens have the calcified portions
comparatively more reduced than the smaller ones. The internal organs closely resemble 5. japonicum
except that the terminal appendages are quite unlike. 5. molliculum has also much in common with
5. curiosum Hoek, from the Malay Archipelago; but that barnacle has the carina less arched, with the
umbo farther from the apex, the scales of the peduncle are far larger, the shape of the carinal latus
differs, and there is a small rostrum. Scalpellum subflavum Annandale is also related, but it has
far larger scales on the peduncle, a more broadly triangular tergum, etc. Only one specimen of
i>. molliculum was taken.

Family LEPAD1D7E.

Genus LEPAS.

Lepas anserifera LinnG

Locality: Albatross station 4920, near Kusakaki-jima, about 90 miles WSW. of Kagoshima Gulf,
surface, on pumice.

Lepas anatifera Linn6.

Locality: Albatross station 4758, 70 miles W. of Cape St. James, Queen Charlotte Island, surface.
Lepas pectinata Spengler.

Locality: Albatross station 4897, 10-20 miles southwest of Goto Islands, Japan, surface.

A much inflated and unusually smooth variety of this species occurs at Bering Island. It has been
figured in Bulletin 60 of the U. S. National Museum, plate vm, figures 5, 6. This form may be known
as Lepas pectinata beringiana, n. subsp.

Genus OCTOLASMIS.

Octolasmis orthogonia (Darwin). [PL xi, fig. 6 and 7.]

1851. Dichelaspis orthogonia Darwin, Monograph on the Cirripedia, Lepadidae, p. 130, pi. 2, fig. 10 (locality
unknown.)

1907. Dichelaspis orthogonia Darwin, Hoek, Siboga-Expeditie, Monographic xxxia, Cirripedia, p. 25, pi. 2, fig. 14-18;
pi. 3, fig. 1, ia, ib, iob, Malay Archipelago.

The type locality of this species was unknown, but the typical form was rediscovered in the Malay
Archipelago by the Siboga Expedition, where it was taken at several stations, in 40 to 1 12 meters. Two
other forms very closely related to orthogonia were taken by the Siboga, Dichelaspis weberi Hoek and
D. versluysi Hoek. Three specimens of 0. orthogonia were taken by the Albatross at station 4936, off
Kagoshima Gulf, in 103 fathoms, seated on Heteralepas. Two of these are figured (pi. xi, fig. 6, 7, no.
38676 U. S. National Museum) to show the variation in shape of the plates, chiefly of the terga. In
the larger specimen (fig. 7), length from apex to base of carina 10 mm., the median and occludent
lobes of the base of the tergum are rather short and acute on the left side, as figured, but noticeably
longer and less acute on the right side. The other example figured (fig. 6) has a capitulum 9.3 mm.
long. The basal lobes of the tergum are very long and finger-shaped. The third example of the group
has a tergum intermediate in shape between the two extreme forms figured. The basal disk of the
carina is formed about as Darwin figures for D. orthogonia.

The variations observed among these three individuals, which clung in a group to the peduncle of
an Heteralepas, show that there is considerable variation in the shape of the terga among adult egg-
bearing individuals. It seems not impossible that the three described species of this type, orthogonia,
weberi and -versluysi might better be looked upon as variations or local races of a single widely distrib-
uted species.

The terga in these specimens are pink-tinted, and the valves are not much covered by cuticle.

BARNACLES OF JAPAN AND BERING SEA.
Genus CQNCHODERMA.

Conchoderma auritum (Linn6). [PI. vm, fig. 5, 6, 7.]

1767. Lepas aurita Linnaeus, Syst. Nat., ed. xn, p. mo.

1851. Conchoderma aurita Linnaeus, Darwin, Monograph on the Cirripedia, Lepadidae, p. 141.

1907. Conchoderma auritum Linnaeus, Pilsbry, Bull. 60 U. S. Nat. Mus., p. 99, pi. ix, fig. 2.

Specimens adhering to Coronula were taken from the throat of a humpback whale in Plover Bay,
Siberia, by Dr. W. H. Dali in 1865, and are now in the U. S. National Museum. Color sketches made
by Doctor Dali from life are reproduced on plate vm. In Atlantic C. auritum the stripes and spots are
dark purple, but these examples are striped and mottled with deep rose color and rose-pink. In structu-
ral characters they agree with Atlantic C. auritum. Small scuta and a very minute carina are
developed.

The Californian specimens described by Doctor Dali (1883) as Otion stimpsoni were marked with
purple, like the Atlantic C. auritum.

Genus HETERALEPAS.

Heteralepas japonica (Aurivillius).

Alepas japonica Aurivillius, Kongl. Sv. Vet. Akademicns Handlingar, bd. 26, no. 7, p. 28, Hirado Strait,
Japan, 80 fathoms.

Locality: Albatross station 4986, off Hokkaido Island, Japan; 430 01' 40" N., 140° 22' 40" E.
in 103 fathoms. No. 38683 U. S. National Museum.

Two specimens taken agree in the main with the above-named species, but differ in certain details
noticed below. The extent of individual and local variation in species of this group is unknown, since
a majority of the species are known from one lot from a single place, or at best from very few lots.

The size of two apparently mature specimens is somewhat smaller than japonica — length of capit-
ulum 10 mm., width 8.5 mm.; length of peduncle 4 mm., length of orifice 3.5 mm. The capitulum is
plump, with only the weak trace of a carina toward the summit. There are three low dorsal tubercles,
two on the back of the capitulum and one on the peduncle at the base of the capitulum. The peduncle
is shorter than in japonica.

The mandible (fig. 4, A) has three slender teeth and a lower point below which the border pro-
trudes. Near the edge it is hairy, and both upper and lower margins are bearded.

The maxilla (fig. 4, C) is deeply excavated below the two great upper spines.

The first cirrus has about 1 1 and 23 segments, though the rami are not very unequal in length.
The second, third, and fourth cirri are long with subequal rami, of about 70 segments in the fourth
cirrus. The fifth and sixth cirri have the inner rami very small, less than half the length of the outer
rami, and composed of 17 segments.

The terminal appendages (fig. 4, B) are very short, 2.75 mm. long, of 7 segments.

The penis is very long, sparsely hairy, with a small terminal tuft.

BULLETIN OF THE BUREAU OF FISHERIES.

The principal differences of these specimens from the types of II. japonica are that while the animal
is somewhat smaller, there are more joints in the cirri, and the teeth of the mandible are more slender.

Heteralepas vetula, new species. [PL xii, fig. i, 2, 3.]

Type no. 38689, U. S. National Museum.

Type-locality: Albatross station 4934, off Kagoshima Gulf, in 152 fathoms.

The capitulum is oval, plump, somewhat tubular toward the orifice, which is more than one-third
the length of the capitulum, and has thin, flaring lips, but slightly crenulated. Along the back a suba-
cute and rather high keel runs from peduncle to summit. The crest of the keel, while irregular, shows
no tubercular prominences or nodes. A stout cord-like ridge runs along each side. These ridges meet
at the baso-carinal extremity of the capitulum, and converge again at the apex, defining a broadly
lanceolate dorsal area, which is somewhat smoother than the slightly wrinkled surface in front of the
ridge. No scuta are visible. The capitulum passes rather gradually into the short peduncle, which is
transversely wrinkled.

Fig. 5. — Heteralepas vetula. A, forty-first and forty-second segments of cirrus v; B, penis; C, mandible; D, maxilla;

E, basal segments of cirrus vi and terminal appendage.

Length of the capitulum 11 mm.; breadth 8 mm.; length of the peduncle 5 mm.; breadth 4.5 mm.

The type specimen was dissected. The mandible (fig. 5, C) has three long conic teeth and a lower
point, the latter with three short spines below the terminal point.

The maxilla (fig. 5, D) has a deep recess below the major spine. Its edge is profusely spinose, the
spines giving place to hairs at the lower angle.

The first cirrus has very unequal rami of 13 and 23 segments, each with a distal circle of hairs.
Cirri ii to iv have equal rami of very numerous segments, as usual in Heteralepas. Cirrus v has rami 11
and 4.5 mm. long, composed of 57 and 22 segments. The outer ramus bears a pair of long spines at the
anterior distal angle of each segment, with several very small ones, and two delicate small spines at the
posterior distal angle (fig. 5, A, forty-first and forty-second segments of cirrus v). The smaller ramus
bears only a few very small and delicate spines. The sixth cirrus resembles the fifth.

The terminal appendage is very minute, not quite 2 mm. long, and consists of nine segments. There
are a few small hairs at the distal articulations, and two at the end (fig. 5, E, t. app.).

BARNACLES OF JAPAN AND BERING SEA. 73

The penis is very small, about 5 mm. long. It has comparatively few annuli, and is very sparsely
hairy (fig. 5,B).

This species has an external recognition mark in the lateral cords, defining a dorsal escutcheon.
Internally the few-jointed inner rami of cirri v and vi, the reduced terminal appendages, and the com-
paratively small number of annuli of the short penis, are characteristic.

A single small example from Albatross station 4892, southwest of the Goto Islands in 181 fathoms,
seems to be referable to H. vetula. It is no. 38685 U. S. National Museum.

Heteralepas, species undetermined. [PI. xi, fig. 8, 9.]

Locality; Albatross station 5049, off the east coast of Hondo Island, Japan, 38° 12' N., 1420 02' E-,
in 182 fathoms.

A single specimen, no. 38682 TJ. S. National Museum, externally perfect, but the internal organs
wholly wanting, seems to represent an undescribed species.

The eapitulum is oval; the carinal border is almost evenly arched and is rounded, with no trace of
a keel; rostral border strongly convex below the orifice. There is a pair of minute narrow, yellowish
scuta; elsewhere the surface is smooth and somewhat transparent. It is flattened laterally, the sides
being even a little concave. The orifice is very small, about one-sixth the length of the eapitulum, and
not in the least tubular. Below it the rostral surface is smooth and rounded, not superficially slit as
in Alepas pacifica. The peduncle is narrow, very short, and coarsely wrinkled transversely.

Length of the eapitulum 1 1 mm. ; width 8 mm.; length of the peduncle 4 mm. ; width 3 mm.

The figures will serve to call attention to this species, which I refrain from naming on account of the
imperfection of the single specimen.

Family BALANIDAE.

Genus BALANUS Da Costa.

SECTION D.

Balanus rostratus Hoek. [PI. xn, fig. 6 ]

1883. Balanus rostratus Hoek, Challenger Report, Zoology, vol. VIII, p. 152, pi. 13. fig. 16-22.

This species was described from off Kobe, Japan, in 8 and 50 fathoms. The type specimens were
small, the largest 9 mm. high, 7 mm. in diameter of base. The types were not furrowed exteriorly, and
the orifice is small. A series from Tokyo Harbor (no. 1814 collections of Academy of Natural Sciences
of Philadelphia) shows that the species attains a far larger size, up to 27 mm. high and 37 mm. in basal
diameter. Some notes on the adult examples may be useful. While usually almost smooth, or only
irregularly roughened, the outer wall is sometimes ribbed in places. The walls and opercular plates
are invariably white throughout, and the egg-shaped orifice is generally about half as long as the base,
which is strong and flat. The basal ends of the parietes show square holes, exactly as figured by Darwin
for B. porcalus of the north Atlantic. The large size of the rostral and diminution of the carino-lateral
pieces has been duly emphasized by Hoek. The radii are deeply sunken below the parietes, appear-
ing as small, narrowly triangular or wedge-shaped spaces, which are delicately and closely striated
transversely.

The opercular plates agree with those described by Hoek, but are less transparent than his figures
indicate, though still thin. The longitudinal striation of the scutum is very distinct and beautiful
though fine, and the transverse ridges are almost lamella-like on the lower part of the plate. They pro-
ject along the occludent margin. The terga show only weak traces of the depressor-muscle crests.
Externally there are some very weak longitudinal striae near the carinal margin. The band leading to
the spur is smooth except for transverse growth-lines; and the surface on both sides of it has extremely
weak oblique riblets, quite narrow and hardly raised above the level surface.

This species, I have little doubt, is identical with “some fine, brilliantly white specimens (without
opercula) from the coast of China” which Darwin alludes to as possibly a species distinct from B. porcatus
(Monograph on the Cirripedia, Balanidae, p. 259).

bulletin of the bureau of fisheries.

B. rostratus agrees with B. porcatus Da Costa in the porose parietes, solid radii and base, but differs
in having the adductor ridge of the scutum wholly free from the articular ridge, and by the absence of
any distinct articular furrow. In B. porcatus and B. nubilis the articular furrow of the tergum is deep.
The wholly white plates are a further distinguishing feature. In B. porcatus the tergum usually has a
purplish spot on the inner face, and a purplish beak.

Balanus rostratus apertus, new subspecies. [PI. xii, fig. 4, 7; pi. xiii, fig. 1, 2, 8, 9.]

Cotypes no. 38667, 38668, 38669, U. S. National Museum, all from station 4778.

Type locality : Albatross station no. 4778, Bering Sea, N. lat. 520 12', E. long. 179° 52' in 43
fathoms. Living embedded in sponges. Also stations 4777 and 4779, on Petrel Bank, Bering Sea,
in 52 fathoms.

The shell is white, subcylindric or conic, with convex sides and a large, triangular-ovate orifice,
frequently as large as the base. The parietes are marked with fine, waved, transverse striae, and

Fig. 6. — Balanus rostratus apertus. A, ist cirrus; B, mandible; C, maxilla; D, 15th and 16th segments of cirrus v.

sometimes bear short, acute spines projecting outward and downward, each prolonged upward in a
short rib. These spines appear in groups and are not numerous when present. The radii are much
wider than in B. rostratus, transversely striated, with the upper edges parallel to the base. They
are only very little sunken below the parietes. Internally the plates are deeply, closely, and sharply
sulcate, and the bases of the parietes have square holes as in B. rostratus. The smooth sheath is
nearly half the length of the shell. The stout, poreless, calcareous base is generally concave externally.
The rostrum is very wide, about as wide at its summit as at the base. Two specimens measure,
(a) height 46, greatest diameter 33, length of aperture 19 mm., length of tergum 22 mm.; (b) height
45, greatest diameter 31, diameter of base 24 mm., length of aperture 26 mm.

The scutum is extremely strongly ridged transversely, the ridges much narrower than the inter-
vals; deeply and closely striated longitudinally, the striae weaker near the edges. Inside there is a
rather narrow, not very high, articular ridge, but only the trace of an articular furrow. The adductor
ridge is rather well developed, long, and wholly free from the articular ridge throughout. The

BARNACLES OF JAPAN AND BERING SEA. 75

adductor and depressor muscle scars are moderately deep. It differs from the scutum of B. rostratus
only in being somewhat more solid, with the adductor ridge a little better developed.

The tergum is thin, rather fragile, narrow, its greatest width contained about 2 times in the
length. Spur wide at the base, tapering to an obtuse, truncate end; situated close to the scutal
margin; decidedly longer than that of B. rostratus. External sculpture of narrow oblique riblets,
much stronger than in B. rostratus, the intervals faintly, weakly striate longitudinally. There is no
groove from spur toward beak, only a flat, longitudinally and transversely striated band. The inte-
rior is white throughout. Articular ridge rather narrow, arched, not much more than half the length
of the valve, stronger than in B. rostratus. Articular furrow only weakly indicated. Crests for the
depressor muscles rather weak and irregular, but much stronger than in B rostratus.

Both of the opercular plates have a thin, yellowish cuticle, whitish in young specimens.

The mandibles of no. 38667 have three rather stout short teeth, then a minute tooth and an
obtuse lower angle. The upper tooth is minutely bifid at the tip. The upper and lower borders are
densely and very finely hairy, as are also the intervals between the teeth (fig. 6 B).

The maxilla; do not differ materially from those of B. rostratus as figured by Hoek, except that
there are several small spines above the two great spines (fig. 6 C).

The first cirrus (fig. 8 A) has very unequal rami of 15 and 27 segments, those of the posterior
branch strongly protuberant at the anterior side, with dense hair-tufts. The second and third cirri
also have unequal branches, the segments of both strongly protuberant, with dense tufts. Cirrus ii
has 15 and 19 segments; cirrus iii, 12 and 19. Cirri iv to vi are of the usual slender and elongate
shape, with subequal branches of about 35 segments. These segments are convex anteriorly, each
with 6 or 7 pairs of spines, and having the usual posterior sutural groups of small spines. (Fig. 6 D,
15th and 16th segments of cirrus v.)

The penis is very long, over 20 mm., purplish, densely and conspicuously annulated, with a very
few short hairs near the end. There is a blunt projection on the dorsal base. The cirri and mouth
parts of the largest specimen in group no. 38670 agree fully with no. 38667.

In this race the radii are scarcely sunken below the parietes. In the type lot the walls form a
subcylindric shell, but in a group of seven individuals seated on a scallop shell, from station 4779,
54 fathoms, the shell is more conic and smoother, the parietes yellowish or dirty white, the radii pure
white. The largest specimen in this group measures 55 mm. high, 45 mm. in greatest diameter of
the base. This group, no. 38670 U. S. National Museum, is figured in plate xn, figure 4.

The cirri of the types of B. rostratus are not fully described. The first cirrus as described by
Hoek agrees with B . rostratus apertus, except in having fewer segments, probably owing to its imma-
ture condition or smaller size. The change in shape between the third and fourth cirri in B. rostratus
apertus is quite abrupt.

Balanus crenatus Bruguifere. [PI. xiv, fig. 1-9.]

1853. B. crenatus Darwin, Monograph on the Cirripedia, Balanidse, p. 261.

Localities: Union Bay, Bayne Sound, British Columbia shore, specimens no. 38671 and 38672
U. S. National Museum; Albatross station no. 5008, Aniwa Bay, Saghalin Island, 24 fathoms,
specimen no. 38674 U. S. National Museum; Albatross station no. 5038, near Urakawa Light, south
coast of Hokkaido, 175 fathoms.

Two forms of this species were taken on shore in Bayne Sound, British Columbia: No. 38671,
a smooth, conic form with triangular parietes and delicately striate opercular plates, the specimen
illustrated having a basal diameter of 14 mm. (pi. xiv, fig. 1, 2, 3); and no. 38672, in which the shell
is more prism-shaped, or columnar with prominent angles, the old ones generally supporting a crop
of younger barnacles at the summit. The opercular plates are much worn and are rather strongly
striate. The figured group is 42 mm. high (pi. xiv, fig. 4-9). The examples from station 5008 are
small and conic, but more rugged than no. 38671.

BULLETIN OE THE BUREAU OF FISHERIES.

Balanus evermanni Pilsbry.

1907. Balanus evermanni Pilsbry, Bulletin of the Bureau of Fisheries, vol. xxvi, p. 203.

In 1906 this fine barnacle was taken at the following stations: Station 4792, near Bering Island,
in 72 fathoms, museum no. 38661 ; stations 4803 and 4804, off Cape Rollin, Simushir I., Kuril Islands,
in 229 fathoms, museum no. 38658, 38659, 38660, 38662. It has apparently a general distribution
from Alaska to the Kuril Islands.

The specimens agree in essential features with those originally described, but show some varia-
tion in the shape of the cup, such as is to be expected in any lengthened acorn barnacle. In a few
examples it flares toward the mouth, like some liliaceous corolla (fig. 7, A, mus. no. 38661). In others

it is shortened and wide (fig. 7, B, mus. no. 38662). In these stumpy examples the rostrum or the
Carina may become longitudinally ribbed, the ribs rounded and not very prominent.

These specimens from the northwestern Pacific agree with those from Alaska in the characters
differentiating the species from the North Atlantic Balanus hameri Ascanius.

Plates of the wall solid, without pores and without radii; base membranous, sometimes with a
calcareous peripheral rim, which is poreless.

This group was instituted by Dr. Hoek for two species, Balanus hirsu/us from the Faroe Channel
and B. corallijormis from near Kerguelen Island. Two more are now described from Bering Sea,
greatly extending the range of the group.

In wanting radii these forms are more primitive than the typical Balani. The teeth of the mandible
are longer and more slender than in most others of the genus. None of them are littoral barnacles.

Fig. 7. — Balanus evermanni, x^.

SECTION G.

BARNACLES OF JAPAN AND BERING SEA.

1 790 52', in 43 fathoms,

Balanus hoekianus, new species. [PI. xm, fig. 3-7, pi. xv, fig. 1-2.]

Type no. 38666 U. S. National Museum.

Type locality : Albatross station 4778, Bering Sea, N. lat. 520 12', E. long
seated on a gastropod shell ( Buccinum ).

A species of the group G of Hoek; base excessively thin, partly membranous; plates of the wall
solid, without pores; no radii.

The shell and opercular plates are white throughout. Shape shortly subcylindric, flaring outward
at the large triangular ovate orifice. The parietes are slightly roughened but not distinctly ribbed
or sulcate, with no chitinous cuticle and no hairs. The alas are smooth, with extremely oblique upper
margins, so that the peritreme is deeply serrate. Internally the walls have a long glossy sheath below
which they are somewhat sulcate, chiefly at the base of attachment.

The rostrum (fig. 8, A, internal view) is much the largest plate. Externally, while it is finely
indistinctly rugose longitudinally, there is no distinct costation, and no trace of radii. Inside the
sheath is tripartite. The carina (fig. 8, B) is strongly concave. The rostro-lateral plate is wide, tri-
angular, with a well-developed ala but no radius. The carino-lateral plate is narrow, recurved, with
the ala wider than the parietal area. Inside
the sheath is bipartite. The strongly recurved
carina is V-shaped above, with wide alre and
smooth, undivided sheath (fig. 8, B, inside
view).

The base is an excessively thin transparent
film, calcareous at the edges, membranous in
the middle.

Height of the shell 8 mm. ; diameter of
the base 8 mm.

Mandible (fig. 9, B) has four principal teeth.

The upper two are rather long and acute, the
second one in the middle of the edge. The
third and fourth teeth are blunt, and there
are two denticles between them. The lower
point is short and slightly bifid. The lower
edge of the mandible is heavily bearded. The
two mandibles are exactly similar.

Maxilla (fig. 9, C) has an even edge except for a notch below the upper two large spines. There
are six or seven large spines and a few smaller ones below the notch. A band along the edge of the
maxilla and below the lower angle is bristly, and there are a few hairs along the upper edge.

The first cirrus (fig. 9, A) has unequal rami of 9 and 13 segments. Those of the longer ramus pro-
trude slightly, and all are densely hairy. The second cirrus has rami of 9 and 1 1 segments which
are convex on the anterior side but do not protrude; third cirrus has unequal rami with 12 and 13 seg-
ments. The other cirri are longer, the sixth with 23 segments, each with three pairs of spines, the
lower pair rather small. (Fig. 9, D, 10th and nth segments of cirrus v.)

The scutum (pi. xm, fig. 3, 4, 5) is moderately thick. It flares outward and is twisted toward
the apex. Externally it is indistinctly marked with fine, weak growth-striae and rather widely
spaced growth-arrest lines which are scarcely raised. Inside there is a short but well-developed
articular ridge, about one-third the greatest length of the plate. The articular furrow is narrow and
distinct though not deep. There is no adductor ridge, though a noticeable thickening extends down-
ward from the lower end of the articular ridge, representing a vestigeal adductor ridge. A shallow
oblong pit marks the insertion of the depressor muscle.

The tergum (pi. xm, fig. 6, 7) is very thick for so small a plate, white, the scutal margin concave,
carinal margin short, strongly convex. The spur is long and narrow, separated from the scutal margin

Fig. 8. — Balanus hoekianus .

A, rostrum; B, carina. Internal
views.

BULLETIN OE THE BUREAU OE FISHERIES.

by nearly its own width. A smooth depressed band runs to it. The area on the scutal side of this
band is marked with widely spaced, strongly arched, linear riblets. The wide area on the other side
has very oblique linear riblets, and an interstitial sculpture of very weak, fine, longitudinal striae.
There are some minute hairs on the cuticular riblets, along the scutal border, but none on the outer
surface of the plate. Internally the upper or beak portion of the plate is transversely striated. The
articular ridge is high and massive, arcuate; the articular furrow wide but not very deep. The crests
for the depressor muscle are short and sharp.

This species is related to B. corollijormis Hoek and B. hirsutus Hoek, the former from southeast of
Kerguelen Island, 150 fathoms, the latter from the Faroe Channel, in 516 fathoms. Both have a more
or less hairy cuticle, while B. hoekianus has no noticeable cuticle on the walls. B. corollijormis has some
resemblance in shape of the walls to hoekianus, but the sheath is shorter, only one-third the length
of the plates, and the tergum is of quite different shape. In B. hirsutus the articular ridge of the tergum
projects conspicuously beyond the scutal margin, in external view, being much larger than in B. hoeki-
anus, and the spur is scarcely removed from the baso-scutal angle of the plate, whereas in B. hoekianus

the baso-scutal angle is conspicuously produced, and the spur is separated from it by at least the basal
width of the spur. The mandible of B. hoekianus has a smaller tuft of hairs on the upper margin, and
the lower teeth are conspicuously obtuse, not acute as in B. hirsutus. This bluntness of the teeth is not
the result of wear, since the unexposed teeth of the next moult, visible through the mandible, are equally
obtuse. The maxillae are also somewhat different in the two species. The number of spines on the
segments of the posterior three pairs of cirri is smaller than usual.

B. hoekianus, named in honor of Dr. P. P. C. Hoek, is therefore quite distinct from its two antipodal
relatives.

Balanus cailistoderma, new species. [PI. xii, fig. 5, pi. xv, fig. 3-7.]

Type no. 38690 U. S. National Museum.

Type locality: Albatross station 5068, Suruga Gulf, Japan, in 77 fathoms.

A species of Hoek’s Section G. Base in large part membranous; parietes solid; no radii. The
shell is in form a broadly truncated cone, the orifice rather large, ovate, with deeply toothed border.
Parietes lemon yellow, fading to whitish near the orifice; alse whitish. Under a lens the exterior is

BARNACLES OF JAPAN AND BERING SEA.

seen to be marked with rather regularly spaced transverse darker lines, those near the base bearing
fine shining bristles in a single close series. These bristles are largely lost on the older part of the wall,
and some specimens lack them entirely.

The rostrum is the largest plate, triangular in shape. Its sheath is tripartite, as usual. The
rostral latera are nearly as large. Like the carinal latera and carina, it has a well-developed, distinctly
sunken ala. The carinal latera are very narrow. The carina is V-shaped in upper view.

The sheath occupies more than half the total height. It is closely ridged transversely, the ridges
narrow, not hairy. Its lower edge is continuous with the surface below it, not in the least overhanging.

The base has a calcareous rim at the edge, sometimes as much as 6 mm. wide. The central part
is membranous.

Altitude of cup about 32 mm. greatest diameter of base 30 mm.; of orifice 16 mm.

The scutum (pi. xv, fig. 5, 6, 7) is curved, the outer side concave, covered with a dense golden
olive cuticle. It is sculptured with well-raised transverse thread-like ridges, each bearing a close

row of minute shining spicules. Along the occludent edge there is a series of oblique nodes, formed by
the enlarged extension of every alternate ridge of the outer surface (pi. xv, fig. 5). Internally there
is a somewhat massive but low articular ridge extending along two-thirds of the scutal margin. The
articular furrow is deep but very narrow. The adductor ridge is represented by a low callus only.
The pit for the depressor muscle has several short but emphatic crests.

The tergum is covered with yellowish cuticle paler than that of the scutum. It has a concave
scutal border, the adductor ridge not projecting beyond it. The convex carinal margin is equal in
length to the basal margin. The spur is short, rather wide, and separated by about half its width
from the baso-scutal angle. A slight depression, marked only with arcuate growth-lines, runs to the
spur. On the scutal side of this band the surface has narrow arched thread-like riblets. The larger
area on the carinal side of the spur-band has similar oblique riblets. There are no noticeable longi-
tudinal striae. The articular ridge is arcuate, rather high; the articular furrow broad and shallow.

BULLETIN OF THE BUREAU OF FISHERIES.

There are some acute crests at the insertion of the depressor muscle, and in old individuals the whole
inner surface is slightly roughened. The spur is not thickened inside, but the scutal border, near the
basal angle, is raised in a thin laminar flange (pi. vm, fig. 3, 4). The inner faces of both scuta and
terga are white.

The mandible (fig. 10, D) has four slender teeth and a lower point. The second tooth stands
midway of the cutting edge. There is a copious beard along the lower margin, and there are some
hairs near the cutting edge. The maxilla (fig. 10, C) has a notch at the upper angle and numerous
larger and smaller spines; both upper and lower margins are bearded. The first cirrus (fig. 10, A)
has subequal rami of 16 and 14 segments, which are rather densely spinose; and while convex at the
sides, the segments do not protrude. The second cirrus has subequal rami of 18 and 22 segments, more
copiously spinose than the first cirrus. Third cirrus, with 25 and 29 segments. The fourth to sixth
cirri are longer and more slender, and are similar in armature. The fifth cirrus has rami of about 48
segments, several of the lower ones difficult to distinguish, as usual. Each segment is armed with two
pairs of very long spines, with a group of quite small spines between and slightly below the large ones
of each pair (fig. B, 32d to 34th segments of cirrus v). The posterior border of the cirri, in the basal
half, is very minutely serrate or shortly spinulose. The penis (fig. 10, E) is remarkably short, only
about 7 or 7.5 mm. long, very closely annulate, and wholly without hairs.

This handsome barnacle is readily distinguished from B. corolliformis and B. hirsutus by the shape
of the tergum, which has a spur distinctly removed from the baso-scutal angle of the plate, and the
articular ridge does not project beyond the regularly concave scutal margin of the plate. In these
characters, B. callistoderma is more like B. hoekianus, in which, however, the cuticle of the opercular
plates and walls is not hairy, the tergum is much narrower, and the smooth sheath has a free lower
edge, as usual in Balanus. In B . callistoderma the sheath is transversely ridged and continuous below
with the rest of the plate, with no overhanging ledge.

Genus ACASTA Leach.

Acasta spongites japonica, new subspecies. [PI. xvi, fig. 1-9.]

Type no. 38681 U. S. National Museum.

Type locality : Albatross station 4936, off Kagoshima Gulf, in 103 fathoms.

A form more closely related to A . spongites than to any other described species. The deep basal
cup is about half the height of the carina, broadly ovate in contour. Externally it has fine, uneven
circular striae and low, inconspicuous, narrow, longitudinal riblets, each terminating in a minute point
on the upper margin. Inside there are no ribs and no teeth at the margin.

The plates of the wall are only loosely connected, and have a few calcareous points or spines. The
radii are narrower than the parietes. The carina is decidedly larger than the rostrum, quite concave
within. The carino-lateral plate has a narrow parietal area, its basal width contained 2 to 2.3 times
in that of the rostro-lateral plate, thus being much wider than in A. spongites. The rostrum is the widest
and shortest plate. Internally the plates of the wall show only the weakest traces of longitudinal ribs
below the sheath, which is continuous with the surface below it and occupies more than half the length
(pi. xvi, fig. 6, 7, 8, 9, interior views of rostrum, rostro-lateral, carino-lateral and carina). The sheath is
glossy, and in the carina and carino-laterals is ridged across with smooth, thread-like riblets. The
rostro-laterals are less strongly ridged, and in the rostrum the ridges are very weak and low.

The scutum (pi. xvi, fig. 4, 5) is concave outside, with sculpture of low transverse lamellae and
delicate radial striae. The articular ridge is rather low and about half the length of the tergal margin.
There is no adductor ridge.

The tergum (pi. xvi, fig. 1, 2) has a concave band from apex to the spur, and is sculptured elsewhere
with transverse threads. The low articular ridge is continuous with a low ridge which continues upon
the spur. The spur is united until near the end with the baso-scutal angle, in this respect being unlike
A. spongites.

This form differs from A. spongites of the Mediterranean, etc., chiefly by the wider parietes of
the carino-lateral plates, the absence of an adductor ridge in the scutum, and the different shape of

BARNACLES OF JAPAN AND BERING SEA.

the spur of the tergum. It is apparently as distinct a form as several which are ranked as species, but
without a large series the constancy of the differential characters can not be tested. I have therefore
ranked the Japanese form temporarily as a subspecies. The type is a unique individual which had been
wholly overgrown and filled up with the sponge-host, but with the walls and opercular plates complete
and perfect.

Genus TETRACLITA Leach,

Tetraclita porosa (Gmelin).

Locality: Matsushima, on shore.

Genus PACHYLASMA Sowerby.

Pachylasma crinoidophilum, new species. [PI. xvii, fig. i-ii ]

Cotypes no. 38675, U. S. National Museum.

Type locality: Albatross station 4934, off Kagoshima Gulf, in 152 fathoms.

A species somewhat related to P. aurantiacum Darwin. Base apparently membranous, walls solid,
not porous. The basal contour is oblong, the ends elevated to conform to the shape of the supporting
crinoid stem, on which the barnacle always sits lengthwise. The carina rises vertically, the other plates
slope inward more or less. Rostrum and rostral latera white, carina, carinal latera and tips of the
opercular plates pink tinted. All of the plates are thin and without radii. The parietes have a fine,
indistinct sculpture of short, irregular impressions vertical to the faint lines of growth. The alae have
very oblique, wide-spaced grooves. The carina and the median latera are large plates, the others being
much smaller.

The rostrum and rostral latera are narrowly triangular, united by linear sutures (pi. xvii, fig. 3, r., r.l.).
Internally the rostrum is glossy and slightly ridged transversely in the upper two-thirds (fig. 6). It has
narrow alae on both sides. The rostral latera are about as wide as the rostrum at their bases, and
obliquely triangular, without alae (pi. x, fig. 7, interior view). The median latera (pi. xvii, fig. 2, m. /.)
are very large, with triangular parietes and an ala of irregular shape. Inside (pi. xvii, fig. 8) the apical
portion of the plate is slightly ridged transversely, the ridges opaque-white; a radius is faintly indicated’
The basal margin of the plate is sharp and smooth. The carinal latera (pi. xvii, fig. 2, c. 1.) are quadran-
gular, about twice as long as wide, and externally are divided by a diagonal ridge into parietal and
alar areas. Internally there is an obliquely ridged area near the beak (pi. xvii, fig. 9).

The carina (pi. xvn, fig. 2, c.) is recurved at the apex, V-shaped as viewed from above. Outside
there is a rather narrow, triangular parietal area, and two much larger triangular alas. Inside more than
half of the plate is transversely ridged, the ridges white.

Length of base 9, width 6.2, height of carina 7 mm.

The scutum (pi. XVII, fig. 4, 5) is triangular, the width half of the length, marked externally with
narrow, widely spaced transverse grooves. Inside the articular ridge is well developed, nearly as long as
the tergal border of the plate. Articular furrow narrow but rather deep. The apical part of the plate is
transversely ridged. The tergum (pi. xvn, fig. 10, 11) has a strong ridge along the scutal border, and is
concave near it. The surface is marked with lines of growth and spaced grooves. Some radial lines
are weakly sketched. Internally there is a very wide but short articular ridge and a deep articular
furrow. There is a group of sharp crests for the depressor muscle, projecting as small teeth at the lower
border of the plate. The tergum has a truncate shape at the apex, and is marked internally with
arcuate ridges there.

The mandible (fig. n, E) has three long, acute teeth and a blunter, multispinose lower point. It
is somewhat profusely hairy, as shown in the figure, the hairs projecting below the lower point.
There is also a patch of hairs on the upper margin.

The maxilla (fig. 1 1, B) has an irregular, step-like edge, with numerous spines, and is hairy on the
upper and lower borders. The first cirrus (fig. n, C) has short unequal rami of 9 segments, which are
very profusely hairy on the inner face, much less so outside. The second cirrus is similar but larger.
The rest of the cirri are quite long, with three pairs of long and one of very short spines on each segment,
and a tuft of several spines at each suture posteriorly (fig. 1 1, A). Cirrus vi (fig. 1 1, F) has rami of 22
48299° — Bull. 29 — ri 6

bulletin of the bureau of fisheries.

and 23 segments. The penis (fig. 1 1, F, p.) is very long, with indistinct traces of annulation. There is a
pencil of hairs at the tip, and a few sparsely scattered elsewhere. Terminal appendages are very minute,
about 1.25 mm. long, composed of 8 rather profusely bristly segments (fig. 11, D).

This species is known by seven individuals, all very similar. It is much smaller than Pachylasma
giganteum (Philippi) of the Mediterranean and P. aurantiacum Darwin from New South Wales, the
only species of the genus hitherto known, and differs from them in so many details that a com-
parison would be superfluous. The specimens had been removed from the crinoids before reaching
me, and therefore the exact nature of the base could not be ascertained. From the thin, acute basal

Fig. ii. — Pachylasma crinoidophilum. A, two segments of cirrus v; B, maxilla; C, 1st cirrus; D, terminal appendage;

E. mandible; F, 6th cirrus and penis.

edges of the plates of the wall, and the nearly perfect condition of the soft parts, I presume that the
base is wholly membranous. The base of the cup is hollowed to fit the stem of the crinoid, upon
which all were seated in a longitudinal position.

Catophragmus (Chionelasmus) darwini Pilsbry.

1907. Catophragmus darwini Pilsbry; Bulletin of the Bureau of Fisheries, vol. xxvi, p. 188.

The Hawaiian barnacle described as Catophragmus darwini Pilsbry, and known by mutilated indi-
viduals only, has many points of resemblance to Pachylasma crinoidophilum. The mouth-parts, cirri, and
penis are very similar, and the terga, scuta, and plates of the wall are alike in many respects. In

BARNACLES OF JAPAN AND BERING SEA

texture and finer sculpture the plates are similar; so that I can not doubt that the forms are related.
Unfortunately the number of plates of the wall is not knowm in the Hawaiian species, since only frag-
mentary remains were preserved; yet so far as these go they indicate an octomerous wall, the median
latera of which are still unknown. The development of an accessory basal whorl of plates in C. darwini
indicates affinity to the genus Catophragmus. I am disposed to believe that when perfect individuals
come to light, C. darwini will prove to belong to a distinct genus, or at least subgenus, intermediate
between Pachylasma and Catophragmus, and distinguished from Catophragmus by the well-developed
caudal appendages, the wall with a single series of accessory basal plates, part of them with alae, and
by the dense, porcellanous texture of all the plates. This group may be called Chionelasmus .

EXPLANATION OF PLATES.

PLATE VIiI.

Fig. 1, 4. Scalpellum rubrum Hoek, lateral and dorsal views of an adult, no. 38680, U. S. National Museum, x 4.7.

Fig, 2. Scalpellum rubrum, rostrum and adjacent parts.

Fig. 3. Scalpellum rubrum , rostrum and adjacent latera seen from the inside.

Fig. 5-7. Conchoderma auritum Linnaeus, posterior, ventral and lateral views of living specimens from Plover Bay,
Siberia Drawn by Wm. H. Dali.

plate ix.

Fig. 1. Scalpellum stearnsi Pilsbry. Young individual, no. 38678, U. S. National Museum, x 6.

Fig. 2, 3. Scalpellum gonionotum Pilsbry. Lateral and dorsal views of the type.no. 38678, U. S. National Museum x 10.
Fig. 4 Scalpellum gonionotum. Rostrum and adjacent plates.

Fig. 5, 6. Scalpellum wellnerianum Pilsbry. Lateral and dorsal views of the type, no. 32679, U. S. National Museum, x 9.
Fig. 7. Scalpellum wellnerianum. Rostrum and adjacent plates.

PLATE X.

Scalpellum japonicum Hoek.

Fig. 1, 2. Lateral and dorsal views, no. 38684, U. S. National Museum, x 4-
Fig. 3. Rostrum of the same individual.

Fig. 4. 5. Lateral view and rostrum of another individual from the same station, x 4, no. 38685, U. S. National Museum.
Fig. 6, 7. 8. Ventral, dorsal, and lateral views of a very young Scalpellum of the japonicum type, x 12.7, no. 38688,
U. S. National Museum.

Fig. 9. Outline figure of the type specimen of S. japonicum, x 5 Y2.

PLATE XI.

Fig. 1.. 2. Scalpellum japonicum biramosum Pilsbry. Right and left lateral views of the type specimen.no. 38686, U. S.
National Museum, x 3.

Fig. 3. Rostrum and adjacent parts of the same individual.

Fig. 4, 5 Scalpellum molliculum Pilsbry. Lateral view (x 3) and rostral detail of the type, no. 38687, U. S. National
Museum.

Fig. 6, 7. Oclolasmis orthogonia Darwin, no 38676. U. S. National Museum. Two varieties from off Kagoshima Gulf,
x 8.6.

Fig. 8, 9. Heteralepas sp. undet. Ventral and lateral views, x 6, no. 38682, U. S. National Museum.

PLATE XII.

Fig. 1-3. Heteralepas vetula Pilsbry. Dorsal, lateral and ventral views of the type, no. 38689, U. S. National Museum.
Fig. 4- Balanus rostratus aperius, no. 38670, U. S. National Museum, natural size.

Fig. 5. Balanus callistoderma Pilsbry, walls of type, natural size.

Fig. 6. Balanus rostratus Hoek, Tokyo Harbor, Japan.no. 1814. Academy of Natural Sciences, Philadelphia, natural size.
Fig. 7. Balanus rostratus aperius Pilsbry, no. 38667, natural size.

PLATE XIII.

Fig. 1. 2. Balanus rostratus apertus Pilsbry. Scutum of no 38667, U. S. National Museum.

Fig. 3, 4. Balanus hoekianus Pilsbry, scutum of type.

Fig. 5. Balanus hoekianus Pilsbry. Profile of scutum of type.

Fig. 6. 7. Balanus hoekianus Pilsbry, tergum of type.

Fig. 8, 9. Balanus rostratus aperius Pilsbry, tergum of no. 38667, U. S. National Museum.

BULLETIN OF THE BUREAU OF FISHERIES.

PLATE XIV.

Fig. i, 2. Balanus crenatus Brugui&re. Top and lateral views of the walls of an individual of the solitary conic form.
Fig. 3. Tergum of the same individual.

Fig. 4. Balanus crenatus , columnar or colonial type. Profile of scutum. No. 38672, U. S. National Museum.

Fig. 5, 6. Tergum of same individual.

Fig. 7, 9. Scutum of same individual.

Fig. 8. Colony of the columnar type.

PLATE xv.

Fig. 1, 2. Balanus hoekianus Pilsbry. Lateral and top views of the walls of the type.

Fig. 3, 4. Balanus callistoderma Pilsbry. Tergum of the type, no. 38690, U. S. National Museum.

Fig. 5. Profile of scutum, occludent aspect, same individual.

Fig. 6, 7. Scutum of same example.

plate xvi.

Acasta spongites japonica Pilsbry.

Fig. 1, 2. Tergum of the type, no. 38681, U. S. National Museum.

Fig. 3. Walls, lateral view.

Fig. 4, 5. Scutum.

Fig. 6-9. Plates of the wall, internal aspect. 6, rostrum; 7, rostral latus; 8, carinal latus; 9, carina.

PLATE XVII.

Pachylasma crinoido philum Pilsbry.

Fig. 1-3. Top, lateral, and rostral views of the type.

Fig. 4, 5. Scutum of same individual.

Fig. 6-9. Plates of the wall. 6, rostrum; 7, rostral latus; 8, median latus; 9, carinal latus.
Fig. 10, 11. Tergum, same individual.

Bull. U. S. B. F., 1909.

Plate IX.

Bull. U. S. B. F., 1909.

Plate X.

- v

Plate XI,

Bull. U. S. B. F., 1909.

Plate XII.

Bull. U. S. B. F., 1909.

Buu*. U. S. B. F., 1909.

Plate XIII.

Plate XIV

Bull. U. S. B. F., J909.

Bull. U. S. B. F., 1909

Plate; XVI

Bull. U. S. B. F. , 1909

Platk XVII

THE FOOD VALUE OF SEA MUSSELS

By Irving A. Held

U. S. Fisheries Laboratory , Woods Hole , Mass.

CONTENTS.

Page.

Introduction 87

Natural history of the sea mussel 87

Form and structure 87

Reproduction 89

Growth 92

Food 92

Enemies and parasites 95

Distribution and habitat 97

Present uses of sea mussels 97

Sea mussels as food 99

Palatability 100

Digestibility 100

Experiments to show available protein 10 1

Metabolism experiments 102

Composition and nutritive value 105

Mussels a cheap food no

Preservation methods in

Canning m

Pickling 1 13

Drying 114

Cold storage 116

Recipes for cooking 1 16

Cultivation of mussels 1 19

Poisonous mussels 123

Summary, conclusions, and recommendations 125

Literature 126

Bull. U. S. B. F., 1909

Plate XVIII

2. — A bed of sea-mussels 1 year old.

THE FOOD VALUE OF SEA MUSSELS.

By IRVING A. FIELD.

U. S. Fisheries Laboratory , Woods Hole, Mass.

J-

INTRODUCTION.

The purpose of this report is to make known the character and food value of one of
our abundant, nutritious, and palatable sea products which has been little utilized up
to the present time. The substance of a previous paper on the subject a is here added
to and amplified into a more complete, and, it is hoped, more useful discussion.

The sea mussel has been, so far as most of this country is concerned, in the category
of many other unappreciated resources which have later become valuable. Familiar
examples are the sturgeon and the eel. Finnan haddie, too, have only recently come
into popular favor. The large snail, or abalone, of the California coast, at first eaten
only by the Chinese, is now relished by the American palate. Raising frogs for market
is now a profitable industry in various parts of the United States, although in 1903
a bill introduced into the Pennsylvania legislature for the protection of frogs was
greeted with shouts of laughter. The mussel bids fair to become as valuable as any
of these products, for its merits are unquestionable, once the groundless prejudice shall
have given way.

The basis of this report is a series of investigations carried on during three summers
for the United States Bureau of Fisheries at its laboratory at Woods Hole, Mass.

NATURAL HISTORY OF THE SEA MUSSEL.

FORM AND STRUCTURE.

The common sea mussel, Mytilus edulis (pi. xvm, fig. 1), along with the oyster and
clam, is a member of the class Lamellibranchia in the phylum Mollusca. In form it is
triangular ovate. The umbo or beak is much pointed and is situated at the anterior end
of the valves (pi. xix, fig. 3). In size it measures from 2 to 4 inches in length and from
1 to 1 p2 inches in diameter. Occasionally specimens 4 yi inches long are found. The
color of the shell proper varies from violet to pale blue. Externally it is covered with
a horny epidermis of shining blue-black. The sea mussel is most apt to be confused

a Field, I. A: Sea mussels and dogfish as food. Proceedings Fourth International Fishery Congress, Bulletin U. S
Bureau of Fisheries, vol. xxvm, 1908, p. 241-257.

bulletin of the bureau of fisheries.

with the horse mussel, Modiola modiola, which it most closely resembles. Close obser-
vation, however, will show that the umbo or beak of the horse mussel is not at the
extreme end of the shell, but a short distance back near one margin, and that the
epidermis is brown instead of blue.

Internally, the most conspicuous part of the body is the mantle (pi. xix, fig. 3 and 4),
which is made up of two lobes, each attached to and filling one of the two valves of the
shell. Just before breeding, the mantles are thick and fleshy and assume a characteristic
color by means of which it is possible, in a general way, to distinguish the two sexes.
The males are white or pink, while the females vary from an orange to a brick red
color. Another means of distinguishing the sexes is to note the surface character of
the mantles, which in males shows closely aggregated follicles filled with spermatozoa
(pi. xix, fig. 1); in the females it presents a uniform granular appearance containing
scattered groups of pigment cells (pi. xix, fig. 2). During the quiescent period the
mantles are thin and almost transparent.

The foot (pi. xix, fig. 3), so well marked in the fresh-water mussel, is a muscular
organ of small size in the sea mussel, tongue-like in form, with a longitudinal groove
on the underside. Its hinder portion contains the byssus gland, which secretes the
byssus or “beard” for the attachment of the mollusk (pi. xix, fig. 3).

There are three important sets of muscles in addition to those in the foot. (1) The
adductors (pi. xix, fig. 3) are two in number. They extend across from one valve to the
other and serve for closing the shell. The posterior adductor is the large muscle which
it is necessary to cut before the shell is opened. The anterior adductor is inconspicuous
and located, as its name implies, at the front end of the shell. (2) The retractors (pi. xix,
fig. 3), which are two in number and serve for withdrawing the foot, are long, narrow,
paired muscles attached to the foot, from which one pair extends forward and the other
backward to attach to the shell. (3) The pallial muscles (pi. xix, fig. 3) are a row of
delicate structures along the border of the mantle which serve to attach it to the shell.

The digestive tract has a complicated arrangement. It consists of a large mouth
(pi. xix, fig. 3) located at the anterior end just in front of the foot, a short gullet opening
into a stomach which is surrounded by a large, dark-colored digestive gland, sometimes
called the liver (pi. xix, fig. 4). From the posterior end of the stomach the intestine
passes backward to the posterior adductor muscle, where it turns forward in an oblique
manner to the left side of the stomach. At this point it turns back again and passes
through the ventricle of the heart and over the posterior adductor muscle to the anus,
which is a short distance behind this muscle. The labial palps (pi. xix, fig. 3), two pairs
of loose flaps which lie just inside the edge of the mantle attached to the lower lip of
the mouth, may be considered as accessory structures of the digestive system. They
are covered with cilia and serve to direct food to the mouth.

The gills (pi. xix, fig. 3) are a pair of filamentous structures extending along each
side of the body from between the inner and outer palps to the posterior end of the
animal. In cross section they present the form of a narrow W attached by the central
part of the letter; the outer and inner arms remain free at their upper ends.

FOOD VAIyUEJ OF SEA MUSSEES.

The kidneys, or so-called organ of Bojanus, consist of two symmetrical sacs on the
ventral side of the body situated one on either side of the foot. Each extends backward
to its opening, which is located on the inner side of the point of attachment of the gill
just anterior to the posterior adductor muscle.

The circulatory system is well developed and completely closed as in all other
mollusks. The heart lies in the mid-dorsal region in a pericardial chamber. From the
heart a single large blood vessel is given off, which passes forward as the anterior aorta.
It breaks up into a network of arteries that ramify all through the body. The blood is
collected into a large, longitudinal vein on the ventral side of the body, from whence it
passes through the kidneys to the gills and finally to the heart. The blood is colorless.

The nervous system, as in other lamellibranchs, is made up of three pairs of gang-
lionic centers connected one with the other and giving off nerves to supply the various
surrounding organs. One pair is located in the head region with a ganglion on each
side of the gullet, another in the foot, while the third, just ventral to the anterior edge
of the posterior adductor muscle, supplies the digestive and reproductive organs, heart,
gills, and posterior portion of the mantle.

The reproductive system is much more extensive than is found in most other mol-
lusks. It is made up of a complicated branching network of canals which radiate
throughout nearly the entire body. Internally each canal ends in a pocket or fol-
licle. Externally the canals open out on either side of the body through a genital
papilla which is at the inner point of attachment of the gills in front of the posterior
adductor muscle and just in front of the kidney opening (pi. xix, fig. 4). Since there is
no definite organ which can be designated as an ovary or testis, it is impossible during
the quiescent period to determine the sex of an individual. In mussels from Woods
Hole, Mass., genital products were found developing in these canals during the early
spring and summer months. (Compare fig. 1-4, pi. xxm). According to Williamson
(1907) the eggs arise from certain minute, brown-colored cells which he found present
in the mantle of the female. My own observations are to the effect that the sexual
products are formed by a process of budding from the cells lining the walls of the genital
canals. At first the cells formed are extremely small and undergo rapid division.
After a time division stops and the cells enter upon a period of growth. By the time
the sperms and eggs are ripe they occupy almost the entire portion of the mantles, which
are greatly distended by them. They fill the floor of the pericardial region, the wedge-
shaped abdomen and cover to greater or less degree the outer walls of the digestive gland
(pi. xix, fig. 3).

REPRODUCTION.

With such an extensive genital system the mussel is capable of producing an
enormous number of germ cells. For the past two summers between 200 and 300
mussels were kept in a shallow trough of running sea water where the process of egg
laying and fertilization could be readily observed. The extrusion of the sexual elements
on the part of two or three individuals began within an hour after bringing them in
from the natural beds, and as time passed the number of spawning individuals

BULLETIN of the bureau of fisheries.

increased. After from twenty-four to thirty-six hours all the ripe mussels of a given
lot were spawned out. It was observed that spawning started soonest among specimens
which had been roughly handled before being placed in the trough. The duration of
spawning varied with different individuals. Some would deposit practically all their
products at one time, which required from twenty minutes to an hour. Others would
spawn intermittently for short periods of several minutes each and finally stop altogether
without having discharged half their genital products.

A male mussel discharges a stream of milt which will color the water for a distance
of i o or 12 feet before becoming too diffuse to be seen. In quiet water a female mussel
will discharge her eggs so that they will fall in a heap. They can easily be removed
by means of a pipette and measured in a graduate, a method which revealed the fact
that mussels lay from i to 4 cubic centimeters of eggs at a single spawning. Knowing
the average diameter of the eggs to be 0.07 mm., it is easy to calculate the number in a
cubic centimeter, which approximates more than 3,000,000. On August 2, 1909, a
mussel 3X inches long was seen to begin the deposition of eggs. A homeopathic vial
of about 10 c. c. capacity was immediately placed in such a position as to receive the
string of spawn as it was discharged. The egg laying proceeded at a remarkably rapid
rate and continued for 15 minutes, when it suddenly stopped.

The mussel was watched for an hour longer and, when it was seen that no more
eggs were to be laid, was removed from the trough and the shells opened to expose the
mantle. The condition found is shown in figure 4 of plate xix. All of the eggs except
little patches here and there near the edge of the mantle had been discharged. Of
course it was not known whether any of the eggs had been laid before this individual
had come under my observation. The number of eggs laid measured 4 c. c., which
means that this mussel liberated in round numbers about 12,000,000 eggs in 15 minutes.
This is possibly more than the number usually produced. Three other mussels under
my observation liberated from 6,000,000 to 9,000,000 each.

The period of reproduction varies for different regions and is influenced considerably
by climatic conditions. It has been hard to determine when the mussel breeds on our
northern Atlantic coast. Verrill and Smith (1873) and Goode (1887) say that the
mussel breeds early in the spring. Ganong (1889), writing in Acadia, states that the
height of the breeding season appears to be April and May. Mr. Charles H. Silverwood,
of Pawtucket, R. I., who for years has been watching the habits of the mussels in
Narragansett Bay, writes that the breeding season varies with the weather, beginning
sometimes as early as the middle of June and lasting until late in August. Mr. George A.
Carman, of Canarsie, N. Y., observes that the mussels in Long Island Sound spawn
during April and May, while those in the open ocean do not spawn until about Sep-
tember 1. My own observations on the development of the sexual organs in mussels
from Woods Hole, Mass., are in harmony with Silverwood’s statement. Specimens of
mussels were collected every month from February 7 until August 24. The mantles were
sectioned and mounted for microscopical examination. The series of preparations
show a gradual development of the sex cells during the whole period. No mature

FOOD VAL,UE OF SEA MUSSEES.

sexual products were observed before July 3. On that date I found spermatozoa,
which, when placed in sea water, were very active; they clustered about the eggs and
by their active movements caused the eggs to slide gradually hither and thither across
the microscopic field.

In England, on the Lancashire coast, Scott (1901) found that the mussels do not
breed until midsummer. He kept the mussels in tanks under constant observation
for a year and made frequent comparisons with those in natural beds. The sex organs
developed at about the same rate in the two lots. The first eggs were discharged on
May 6 by individuals in both the tanks and the beds. No spermatozoa, however, were
observed until June 13 and the first developing eggs were found on June 14. The spawn-
ing season continued up to the middle of July. In France, where the water is much
warmer than on our coast, the mussel spat appears in February and March. It is clear
from the above evidence that the mussel breeds at various times between the months
of February and September according to the temperature of the water in which it lives.

The ripe egg is a spherical body so small as to be hardly visible to the naked eye.
It is surrounded by distinct membrane. On account of the great number of opaque
yolk granules which fill the egg, none of its internal structures, such as the nucleus
and nucleolus, are clearly visible under the microscope. The spermatozoa are pin shaped,
with a conical protuberance upon the head. When liberated in the water they swimabout
actively and show great tenacity of life. Specimens placed in a bowl of sea water kept
up active movements for more than six hours.

It has been an open question whether fertilization of the eggs takes place within the
body of the female or not. M’lntosh (1885) and Wilson (1886) believe that it is accom-
plished outside of the female. That this is possibly so, Wilson has demonstrated by mix-
ing ripe ova and spermatozoa in a beaker of sea water. He obtained the sexual products
by mincing up portions of the mantle of the two sexes. Scott (1901), who studied the
mussels kept in tanks, believes, on the other hand, that fertilization of the eggs takes place
in the branchial chamber of the mother. He observed that “the embryos flow from the
female in a slow, distinct stream.” If the water is quiet, they settle on the bottom,
forming a pinkish mass. In this position they continue to develop for from eight to
twelve hours, finally becoming ciliated larvae, which rise to the surface and swim about.
At this time they are borne hither and thither by the tidal currents for about four days,
so that eventually they reach almost every yard of our coast line within their range. At
the end of this period the larvae undergo important changes. They develop a shell and
settle upon seaweeds, hydroids, or other convenient objects for attachment. At this stage
they vary from tJt to of an inch in diameter. The foot now becomes the chief organ
of locomotion. By means of it they can creep from unfavorable situations over seaweeds
and other objects to a more suitable position. In young forms the foot is capable of
great extension and has the appearance of a long, white, flexible thread. By extending,
attaching, and contracting this foot, the mussel readily draws itself forward. Of the
myriads of brood mussels that appear shortly after the breeding season, only a small
portion ever reach suitable places for growth, and of these only a few are destined to
reach maturity.

BULLETIN OF THE BUREAU OF FISHERIES.

GROWTH.

The rate of growth is dependent upon circumstances of situation, temperature,
salinity of the water, and the amount of food available. Mussels in sheltered positions
grow more rapidly than those exposed to the force of waves. The ideal location for the
mussel is an estuary where food is supplied in great abundance, where the exposure to air
between tides is not long, and where there is no deposition of silt. In such a place, if not
too thickly crowded, they may grow to the average size of 2 or 3 inches in length in a single
year. On the English coast, where they are cultivated by the bed system, it requires not
less than two years and usually three years for them to reach a length of 2 inches. In
France, where they are cultivated by the buchot method, that size is acquired in about
a year and a half. O11 our Atlantic coast Charles H. Silverwood, of Pawtucket, R. I.,
says the mussels of Narragansett Bay reach marketable size, which I take to be not less
than 2 inches, in from twenty-eight to thirty-four months.

Overcrowding is a very important factor affecting the growth of mussels. A single
pair produces myriads of young, most of which are doomed to early death through lack
of space and other conditions necessary to growth. After the free swimming stage is
over, the young mussels often apply themselves in such close proximity to each other
that no space is left for increase in size. In order to grow it is necessary for the stronger
to smother out the weaker competitors. Sometimes the death rate from this cause is so
high that the many disintegrating bodies apparently contaminate the closely applied
living individuals and cause their destruction. This process may go on so far as practi-
cally to destroy what looks like a promising bed. Mussels on the margin of a thick
cluster will almost always be found larger and in a more thrifty condition. Consequently,
the healthiest individuals and specimens of largest size, other conditions being the same,
are found in beds where the mussels do not lie in close contact with each other.

FOOD.

The food of the mussel is an important topic for study. A knowledge of the food and
feeding habits of the marine animals which are utilized as food by man is of much greater
importance than is ordinarily supposed. Especially is this true of forms like the mussel
and oyster, which may be propagated by artificial means. The agriculturist who plants
his grain regardless of the presence or absence of nitrates, phosphates, and sulphates in
the soil is apt to reap very small crops. These chemical substances constitute an
essential part of the food of plants, and the amount of the harvest’s yield depends
largely upon their presence in the ground on which it grows. The important relation
of soil composition to crop production is well known and is receiving very serious
investigation in every State of the Union.

The cultivation of marine products depends upon this same principle. The would-be
oyster culturist who plants his seed oysters in any convenient spot, without knowledge of
what constitutes their food or of its presence in the water, will be even less successful than

FOOD VALUE OF SEA MUSSEES.

the farmer who ignores the first principles of agriculture. Up to the present time,
however, very little study has been made of the food of marine animals or of the relative
fertility of the waters in various parts of the sea. Such investigations as those of Peck
(1894 and 1896) on the sources of marine food, and of Moore (1907) on the food of the
oyster are of very great economic value.

My observations on the food of the mussel were necessarily limited. They were con-
fined to the vicinity of Woods Hole and to the months of July and August. Lack of
time did not permit a determination of the food value of the water over the mussel beds.
During the summers of 1908 and 1909, however, a microscopic examination was made of
the material found in the digestive tracts of 50 mussels.

Two methods were employed. The first was to extract the stomach contents by
means of a pipette, which was thrust down the animal’s gullet. The substance drawn
out from the stomach was mixed with a few drops of water and a thin layer spread
across the middle of a microscopic slide. The slide was then passed several times
through the flame of an alcohol lamp, until the organisms were thoroughly fixed by the
heat and the water almost evaporated to dryness. A drop of glycerin or of hot glycerin
jelly was next applied and a cover glass pressed down upon it. Permanent mounts
were later made from these preparations by cleaning the slides outside the boundary
of the cover glass and ringing the mounts first with King’s cement and, twenty-four
hours later, ringing them again with asphaltum. This method proved best for pre-
serving the animal forms, Protozoa, found in the stomach.

The second method was to place the mussels, immediately after removal from their
natural beds, in small dishes of filtered sea water. After two or three hours’ time the
bottoms of the dishes were covered with intestinal discharges, which were removed by
means of a pipette and transferred to a vial containing 95 per cent alcohol. After the
sediment had completely settled the alcohol was drawn off and fresh alcohol added.
The process was repeated, using absolute alcohol instead of the weaker grade. This
was followed by a few minutes’ treatment with xylol, and after removing most of the
xylol three or four drops of a rather thin solution of Canada balsam were added. This
mixture was allowed to stand for a few hours, until the xylol, sediment, and balsam were
thoroughly mixed. Then, by means of a pipette, a large drop was transferred to a
microscopic slide and on it was placed a cover glass. This method was found best for
the preservation of the plant organisms which are known as diatoms. The diatoms,
thus prepared, have had the pigments and coagulated protoplasm more or less com-
pletely removed, leaving a clear view of the striations and other markings on the
skeleton.

The food of the mussel was found to consist of microscopic plants and animals which
are carried by chance to the mollusk by water currents and are swept into the mouth
by means of cilia on the gills and palps. The wall of the gullet is also lined with cilia,
which direct the movement of the food material into the stomach. Not only food, but
dirt and other indigestible substances are swept in. From the alimentary tracts of 50

bulletin of the bureau of fisheries.

mussels there were found 29 species of diatoms and 9 species of Protozoa.® The relative
abundance of each species is indicated in the following list :

Organisms Constituting the Food or the Mussed.

diatom ACEA3. [Plates xx and xxi.]

Actinoptychus undulatus Ehrenberg (fig. 12) Common.

Amphiprora lepidoptera Cleve Very common.

Amphora proteus Gregory (fig. 2) Frequent.

Biddulphia favus (Ehrenberg) H. V. H. (fig. 11) Do.

Biddulphia rhombus (Ehrenberg) W. Smith (fig. 1) Do.

Coscinodiscus excentricus Ehrenberg (fig. 25) Do.

Grammatophora marina Kiitzing (fig. 16) Do.

Hyalodiscus subtilis Bailey (fig. 23) Very common.

Melosira sculpta Kiitzing (fig. 14) Do.

Navicula didyma Ehrenberg (fig. 6) Common.

Navicula lyra Ehrenberg (fig. 8) Occasional.

Navicula lanceolata Kiitzing (fig. 7) Frequent.

Navicula splendida var. puella Ad. Schmitz (fig. 10) Occasional.

Nitzschia sigma Grunow (fig. 15) Common.

Nitzschia sigma var. rigida Grunow Do.

Nitzschia sigma var. sigmatella Grunow (fig. 13) Do.

Pleurosigma affine Grunow Frequent.

Pleurosigma angulatum W. Smith (fig. 24) Do.

Pleurosigma balticum W. Smith (fig. 18) Common.

Pleurosigma decorum W. Smith (fig. 20) Do.

Pleurosigma elongatum W Smith (fig. 19) Do.

Pleurosigma naviculaceum Brebisson Very common.

Rhabdonema adriaticum Kiitzing (fig. 5) Frequent.

Rhabdonema arcuatum Kiitzing (fig. 9) Do.

Rhizoselenia setigera Brighter (fig. 17) Very common

Stephanopyxis appendiculata Ehrenberg (fig. 21) Occasional.

Surirella ovalis var. ovata Brebisson (fig. 4) Common.

Synedra gallionii Ehrenberg (fig. 22) Very common.

Tabellaria fenestrata Kiitzing (fig. 3) Frequent.

protozoa. [Plate xxu.]

Ceratium fusus Ehrenberg (fig. 3) Frequent.

Distephanus speculum Stohr (fig. 4) Common.

Exuvisella lima Ehrenberg (fig. 5) Very common.

Exuviaella marina Cienkowsky (fig. 1) Common.

Glenodinium compressa Calkins (fig. 2) Do.

Peridinium divergens Ehrenberg (fig. 6) Do.

Prorocentrum micans Ehrenberg (fig. 7) Very common

Tintinnopsis beroidea Stein (fig. 9) Do.

Tintinnopsis davidoffi Daday (fig. 8) Common.

“The identifications were made by Mr. T. E. B. Pope, assistant of the Bureau of Fisheries.

FOOD VALUE OF SEA MUSSELS.

The organisms included in this list are of the most primitive type, and, as Peck
(1896) has demonstrated, are the ultimate source of food for all marine animals. The
food of diatoms is the dissolved mineral matter removed from the soil and carried by
rivers and the smaller streams down to the sea. It is absorbed through the surface
of their bodies and transformed into living tissue. When their bodies have increased
to a certain size, each individual divides into 2 ; as these grow they divide into 4, the 4
into 8, 8 into 16, etc., in geometric ratio. Under favorable conditions multiplication
by this means is so rapid that millions may be produced in a day from a single individual.
The Protozoa on which the mussel feeds multiply in much the same way, but in feeding
habits differ from the diatoms in that they consume solid food, chiefly diatoms, in
addition to absorbing soluble nourishment through the surface of the body. It is
interesting to note, as Professor Brooks has pointed out, that these unicellular organ-
isms are the means of bringing back to us in the form of food our mineral wealth which
is continually being lost through the agency of erosion and solution.

ENEMIES AND PARASITES.

The enemies of the mussel are numerous. Killifish, cunners, and scup are very fond
of the young mussels, greedily stripping them from the wharf piles, seaweeds, and other
objects of attachment. The squeteague and tautog eat them from the beds. Among
the mollusks the drill, Urosalpinx cinereus, destroys large numbers by boring a hole
through the shell to the soft parts on which it feeds. On nearly every mussel bed
numbers of shells may be found pierced with a hole about the size of a pin head which
testify to the ravages of this voracious snail. Another snail, Neverita duplicata, is
supposed to feed upon them in the same manner but the hole drilled is much larger.
The so-called whelks, Busycon canaliculata and B. carica, also prey upon them to
considerable extent. Perhaps the worst enemy is the starfish, which destroys them to
as great a degree as it does the oyster. In England, Lebour (1907) reports that one
whole bed of mussels at the mouth of the River Tyne was completely destroyed by
this echinoderm. Crows and rats are said sometimes to eat mussels from the beds when
they are exposed. Seaweeds like Ulva and eel grass ( Zostera marina ) are very injurious
to the health and growth of mussels when they spread over the beds. Two of the largest
beds near Woods Hole, Mass., have been practically ruined this year (1908) by a dense
mass of eel grass which has sprung up over them. The weed by its growth not only
gradually smothers the mussels, but causes the sand and mud to silt over them at such
a rate that in a few months all signs of the bed are obliterated. The decaying bodies
of the shellfish fertilize the soil and finally what was once a bed of mussels is a thrifty
bed of eel grass.

The parasites of the mussel are few. The most common one is a little crab, Pinno-
theres maculatum, which is very similar to the oyster crab but larger and with a tougher
shell. It apparently works no injury to either the health or growth of the shellfish.
Indeed, some observers believe the relation is symbiotic rather than parasitic. The

bulletin of the bureau of fisheries.

crab lives in the gill chamber, where it is protected from outside harm. In return for
this protection it is said that the crab runs out and collects food which on returning it
chews up in the gill chamber and shares with its host. From the examination of the
stomach contents of several of these crabs, however, I found no evidence to support this
belief. The only food material found consisted of diatoms and other microscopic
organisms which probably would have been utilized by the mussel had not the parasite
been present. Other hosts, such as the giant scallop and smooth scallop, are known to
harbor this same species of crab. In describing it (Goode, 1884), Rathbun says:

Another species of Pinnotheres ( P . maculatum ) frequently occurs in the shells of the common sea
mussel ( Mytilus edulis) and the smooth scallop ( Pecten tenuico status), between the gills of the animal.
It attains a size larger than the oyster crab, and, as in the case of the latter, the females alone are para-
sitic, the males only having been found swimming at the surface of the sea. We have never heard of this
species being eaten, probably because neither the mussel nor the smooth scallop has ever been used as
food in this country. In the summer of 1880, while dredging off Newport, R. I., the United States
Fish Commission steamer Fish Hawk came upon extensive beds of the smooth scallop, from a bushel
of which nearly a pint of these crabs were obtained. Again, in 1881, the same species was encountered
in great abundance by the same party in Vineyard Sound, in Mytilus edulis. As an experiment, they
were cooked along with the mussels and found to be very palatable, although their shell is, perhaps,
somewhat harder than that of Pinnotheres ostreum.

In my own experience with mussels I have observed no other parasite, but in
Europe Lebour (1907) found a boring annelid, Polydora ciliata, which attacks the
Northumberland mussels. The worm burrows through the shell from the outside,
making a hole about the size of a pin. It causes the mussel to grow pearly excresences,
often to considerable extent, over the internal surface of the shell, which interfere with
the muscular development of the animal and frequently almost destroys the posterior
adductor muscle. If the pearly masses press upon the mantle, the reproductive lobes
fail to develop in such places. Aside from injuring the mussel, the presence of the
pearly excrescences gives the mussel an unsightly appearance and consequently renders
it unfit for market.

Three larval trematodes are also found in the Northumberland mussels. The
cercarias of the pearl trematode have been found in the mantle, the encysted cercarias
of Echinostomum secundum in the foot, and a third unidentified species encysted in the
liver. These trematodes, however, even when present in large numbers, work very
little injury to their host.

Several species of mollusks are commonly found living with the sea mussel. Oysters
are very often associated in the same beds with them and usually to the detriment of
the oyster, if the mussels are present in large numbers. The mussels, having the power
of free movement which the oysters do not possess, are able to acquire the more favorable
positions for collecting food and thus deprive the oysters of much nourishment. The
soft-shelled clam, Mya arenaria, and the hard-shelled clam, Venus mercenaria, are
sometimes found growing among the mussels in good, healthy condition. Boat shells,
Crepidula fornicata and C. convexa, are very common. Sometimes three or four individ-
uals are attached to a single mussel, covering it almost completely, but apparently doing

FOOD VALUE OF SEA MUSSELS.

no injury. Large numbers of periwinkles, Littorina litorea, are usually present on the
beds, where, according to Allen and Todd (1902), by feeding upon the seaweed and
thus keeping down the growing vegetation, they are a positive benefit to the mussel.

distribution and habitat.

The sea mussel has a very wide distribution, occupying most of the coast line of
the northern half of the Northern Hemisphere. It is circumpolar in range and extends
down our eastern coast to North Carolina, down the Pacific coast to San Francisco,
Cal., on the Asiatic coast to Japan, and on the European coast southward to the Medi-
terranean Sea. It is extremely abundant in the shallow, sheltered bays along the coasts
of New Jersey, Long Island, Rhode Island, and Massachusetts.

The mussel seems to grow equally well in shallow and deep water. The bathy-
metrical range is from the littoral zone to about 100 fathoms. In the channel between
Eastport, Me., and Deer Island, Verrill and Smith (1873) dredged them in from 40 to
50 fathoms and report that later their party dredged them in deeper water, but do not
state from what depth. Some of the beds near Boston, Lynn, and Vineyard Sound
lie in from 5 to 7 fathoms of water.

The favorite habitat of the mussel is where the water is slightly brackish, in shallow,
protected bays and estuaries, on a bottom of mud rich in diatoms and covered more or
less with stones or other solid objects to which it may attach by means of its byssal
threads. The swift tideways of shallow inlets are also very good situations for the
mussel. In these localities it is generally distributed from halfway between tide
marks to a level several feet below low water. Other situations chosen by the animal
are the piles and timbers of bridges, wharfs, and other objects, buoys, light- vessels,
and rocks. But these locations are not so advantageous as the first ones mentioned,
where mussels thrive in enormous beds, sometimes acres in extent, and where it is
possible for a man to collect them daily by the ton.

PRESENT USES OF SEA MUSSELS.

The sea mussel, which is practically unknown as a food in the United States outside
of New York City, has been utilized in other parts of the world for hundreds of years.
According to Ouatrefages (1854) the artificial culture of mussels for food began as early
as the year 1035. Gould (1870) states that this shellfish is extensively used as a food in
England, France, Norway, and Russia, and that it is more palatable than the common
clam, Mya arenaria. Anderssen (1880) refers to it as a cheap and healthful food in
America, France, Spain, and Portugal, where it is eaten raw with vinegar and pepper or
boiled with milk. Goode (1884) writes that in Europe Mytilus holds an important place
among the sea foods. Ganong (1889) says that as a food in Europe the mussel ranks
second only to the oyster and takes the place of the soft-shelled clam, which is not
eaten. This state of affairs we find at present reversed in America, where the soft-
shelled clam is so popular that there is danger of the demand exceeding the supply,
while the mussel, although exceedingly abundant, remains almost unutilized.

48299° — Bull. 29 — 11 7

bulletin of the bureau of fisheries.

In the early colonial days, however, the settlers did eat mussels, as may be seen in
Lescarbot’s description of De Mont’s settlement at St. Croix Island (Dochet Island of
to-day), written in 1604. From this account Ganong (1889) makes the following
quotation :

There is a little chapel built after the fashion of the savages, at the foot of which there is such a
store of mussels as is wonderful, which may be gathered at low tide, but they are small. I believe
that Monsieur De Mont’s people did not forget to choose and take the biggest and left there but the
small ones to grow and increase.

Of how the change in attitude toward the mussel and clam came about Ganong
(1889) offers a very plausible explanation. He attributes it to the influence of the
Indians, who ate the soft-shelled clam to the almost total neglect of the mussel, which,
without reason, they superstitiously avoided. He furthermore thinks that this was
unfortunate for us, since the mussel is a superior article of food. Goode (1887) refers
to the use of mussels on the northwest coast of America, where it is the chief molluscan
food. The Indian women and children collect them from the rocks every day the year
around. Mussels are also consumed by the white inhabitants of that region. The
Russian name for them is “black shells” (chornie rakooshka). In Alaska the method
of cooking is by boiling; on Vancouver Island they are more commonly roasted.

Aside from being useful as an article of food, the sea mussel is valuable for other
purposes, the most important of which is bait. In England the mussel is valued as
the best hook bait known. The quantity used in Great Britain for this purpose amounts
to more than 100,000 tons annually. In this country, however, fishermen rank it
second to the squid in bait value.

Next in importance the mussels are valuable for the production of fertilizer. The
so-called mussel mud constitutes one of the best fertilizers known. It is formed in
places where the mussel beds are exposed to constantly depositing silt, which slowly
destroys the mollusks and buries them beneath their offspring. The slow accumulation
and decay forms a mass of very rich fertilizer, enormous quantities of which are taken
along the coasts of Long Island and New Jersey, where it is considered excellent for
carrots and onions. Goode (1887) stated that for the last thirty years he had seen it
applied to lands where onions had been grown with a product varying from 300 to 600
bushels per acre. At that time the mussel mud sold, delivered several miles from where
it was dug, at $4 to $5 a cord. It is gathered during the winter, piled up and exposed
to the frosts, and then distributed in amounts of from 4 to 8 cords to the acre. For
bait and fertilizer the value of the mussel fishery to the United States is estimated at
$37,500 annually.

Pearls of some value are sometimes found in mussels. Usually, however, although
quite commonly present, they are small and of such poor color that the price they bring
is low. In England they have been sold for from is. 6d. to 4s. per ounce.

The shells can be used by oyster planters for cultch upon which to catch oyster
spat. When polished, they may be used in numerous ways. Artists use them as
receptacles for gold or silver paint. They may be mounted on marble for paper weights

FOOD VALUE OF SEA MUSSELS.

or made into pretty needle books and scent bottleholders, earrings, crosses, pins, and
pin cushions. It is said that the American Indians and the natives of New Zealand
used the mussel shells as tweezers for pulling out their beards.

SEA MUSSELS AS FOOD.

The fact that the sea mussel is so widely used as a food and yet is not utilized to
any extent in the United States, where it grows prolifically in great beds, has led me to
investigate its properties as a human food and to determine whether or not there is any
reason for not making wide use of it in our diet. A food substance to be of value must
measure up well to four standards. It must be palatable, digestible, nutritious, and
economical.

By palatable I mean that the substance must have a flavor that will appeal to the
average man’s taste. To determine this quality, I found it necessary first to taste or
eat the substance in question myself. If the flavor was agreeable and no evil results
followed its use, I persuaded members of the Woods Hole scientific staff to follow my
example and express their opinions concerning the dish. If they gave a favorable
report, I had mussels served on certain tables of the Marine Biological Laboratory
mess hall and to other persons who were interested enough to try them. The general
opinion expressed was taken as an indication of the palatability of the food. By this
method it was often possible, also, to obtain criticisms which would suggest new ways
of preparing the substance to improve its flavor.

The second standard, digestibility, means several things. It relates to the propor-
tion of the food that can be digested, to the ease or rapidity with which it can be digested,
and to the degree in which the material agrees or disagrees with the user. Compara-
tively little is known concerning the relative rapidity of digestion of different foods
within the body. Most of the current statements referring to this are apparently based
on experiments carried on outside of the body, and it is certain that the processes in the
two cases are not exactly the same. The artificial process takes much longer than the
natural one, although the relative rates of digestion as regards different substances
appear to be much the same. For example, under natural conditions, soft boiled eggs
will digest more quickly than hard boiled ones. The same proportionate results are
obtained by the artificial method. The artificial process serves merely to determine
the rate of digestion of the substance compared with that of staple foods. How it
agrees or disagrees with the user can only be determined by taking the article into one’s
own stomach and awaiting results.

The third standard, nutritive value, involves such questions as the ratio of edible
portion to refuse and the chemical composition and proportion of nutriment that can
be absorbed by the body under normal conditions.

The fourth standard, economy, means that a food of high nutritive value must be
so abundant and easily obtained that it can be sold reasonably cheap. If it can be
readily prepared in various ways so that it may be preserved for long periods, its value
is still further increased. Any food that measures up well to these four standards ought
to find a large and ready market.

IOO

BULLETIN OF THE BUREAU OF FISHERIES.

PALATABILITY.

From the standpoint of palatability I have abundant testimony from scores of
persons who have eaten mussels prepared in various ways (pickled, steamed, roasted,
stewed, and fried) that in flavor and texture they are superior to the long clam and
fully equal to the oyster. A few people were inclined to rank them not so high. On
July 30, 1907, pickled mussels were served on three tables of the Marine Biological
Laboratory mess hall. About 36 persons ate of them and all expressed their appre-
ciation of the unfamiliar dish. The only adverse criticism that was made related to the
tough, muscular part of the foot, which was difficult to masticate.

Two days later one of the residents of Woods Hole was given four dozen mussels,
which he took home for family use. He had them steamed and served with salt, pepper,
butter, and oil. They were pronounced “elegant and superior to clams.”

On August 3, 1907, mussels dipped in egg and cracker crumbs were fried and served
to about 25 persons at the Marine Biological Laboratory mess hall. They were declared
to be equal to or better than fried oysters, and were so relished, in fact, that there was a
general call for more. A few days later, in answer to this request, a large quantity
was prepared and served to 40 persons. Enthusiastic comments were made as to the
appetizing appearance, rich flavor, and delicate texture of the flesh.

On August 13 mussel chowder was served to the same 40 persons and called forth
the same favorable comments, especially as to richness of flavor and tenderness of the
meat. The tender quality of the flesh is a point decidedly in favor of the mussel when
compared with the clam, the meat of which latter in chowder is so tough that few persons
ever think of trying to masticate it.

Mussel fritters were next tried on the tables of the mess hall on August 27. They
were eaten with relish and pronounced excellent.

The following year, 1908, the work of preparing mussels in various ways and serving
them in the mess hall to friends and visitors of the Bureau’s laboratory was continued,
with the result that quite a general interest in the food value of this shellfish has been
aroused and a local demand now exists. For some years past at certain points along
the coast of Rhode Island, New York, and New Jersey a few people have been in the
habit of collecting mussels for their own personal use. Some of the summer visitors
also have learned to eat them. I have met several persons living in the vicinity of
New York City who say they have always prized the sea mussel as a food and that it
is their custom to pickle a number every summer for use during the winter.

For the benefit of those interested in making use of the mussel in their diet, a few
recipes for cooking them will be given in another section of this paper. They have been
tried repeatedly and have proved to make most palatable dishes.

DIGESTIBILITY.

Personal testimony in various instances is very favorable to mussels for their
digestibility. Persons with weak stomachs say that they can eat them without suffering
any inconvenience. Others have eaten them just before retiring and experienced no

FOOD VALUE OF SEA MUSSELS.

IOI

discomfort. One man with whom meat dqes not ordinarily agree states that he can
eat freely of mussels and digest them without difficulty. Many persons have declared
that in their opinion mussels are more digestible than either clams or oysters, a fact
due to the character and properties of the flesh which by cooking is rendered tender
and mealy, whereas the oyster and clam become very tough.

But the problem of really determining the digestibility of a given food material is
surrounded with great difficulties. It is an easy matter for one to eat the food and learn
by experience how it agrees or disagrees with him; but to determine the rate of diges-
tion and the proportion of nutriment which the body absorbs from a given quantity of
the food involves a series of very complex chemical studies.

EXPERIMENTS TO SHOW AVAILABLE PROTEIN.

By artificial methods it is possible, however, to determine approximately the pro-
portion of protein which is rendered soluble and absorbed by the animal body. Diges-
tion experiments of this sort were made by Dr. C. L. Alsberg. His method and results
are as follows :

Mussels, hard-boiled eggs (yolk and white together), and thoroughly boiled beef were each ground
up in an ordinary kitchen sausage machine. Each chopped-up sample was thoroughly mixed to make
it as uniform as possible. Then 5-gram samples were weighed out. Each sample was placed in a
flask containing 100 c. c. of artificial gastric juice. This juice was prepared by dissolving 0.5 gram
pepsin in 1 liter 0.15 per cent hydrochloric acid. All the flasks were placed in a thermostat at a
temperature of 38° C. At stated intervals they were all shaken by hand. After two hours one-half
the flasks were removed from the thermostat. The remainder were removed after four hours. Imme-
diately after taking them out of the thermostat each flask was brought to a boil in order to destroy
the enzymes. Each was then filtered through an ash-free quantitative filter, and when all the liquid
had passed through the filter the undissolved residue was washed with 100 c. c. of distilled water.
When all the wash water had passed through the filter, the amount of nitrogen was determined by
the Kjeldahl method in the combined filtrate and wash water as well as in the undissolved residue.
From the relative amounts of nitrogen in the filtrate and undissolved residue an opinion may be
formed as to how much protein has been rendered soluble by the action of the gastric juice. This
method is not accurate, but it is believed to be more accurate than the methods commonly employed,
in which the various digestion products are precipitated out and weighed. The washing and drying
of such proteins upon filters presents great difficulties. It is believed that the determination of the
nitrogen rendered soluble gives a better index of the effect of the digestion. The figures obtained
were multiplied by 6.25 to indicate the amount of protein corresponding to them. The resulting
figures are given in the following table, each figure representing the average of several experiments:

Table i. — Results of Experiments to show Available Protein in Mussels.

Substance.

Protein in
filtrate.

Protein in
residue.

Per cent dis-
solved.

For two hours’ digestion:

Grams.

Gram.

Mussels

0. 5783

0. 201 2

74- 1

Beef

1 . 1656

■ 2705

81 . 1

For four hours’ digestion:

Mussels

. 6107

. 1522

80. 0

■ 7455

. 2104

77- 9

1. 2930

• 1450

96. 7

102

BULLETIN OF THE BUREAU OF FISHERIES.

It will be seen that under the conditions of these experiments there was no very
great difference in the digestibility of the egg and the mussels, while the beef was con-
siderably more digestible than either. It must, however, be pointed out that beef has
more nitrogenous extractives than egg and that the greater digestibility of the beef
may be accounted for in part by the fact that under the conditions of these experiments
the nitrogenous extractives are calculated as protein. How much nonprotein nitroge-
nous extractives mussels contain is not known. It must be noted, however, that, judged
by sight, the greater part of the mussels went into solution. The undissolved portions
consisted mainly of the tough portions, such as the foot and posterior adductor muscle.

Finally, it should be pointed out that experiments such as these must be inter-
preted cautiously. Digestion in vitro is surely not so effective as digestion in the intes-
tinal canal. It is even probable that in the intestinal canal all these three foodstuffs
may be equally perfectly utilized. This can be determined by careful metabolism
experiments.

METABOLISM EXPERIMENTS.

The metabolism experiments were made a special subject of research by Dr. Donald
D. Van Slyke, assisted by Messrs. W. M. Clark and C. B. Bennett. In Doctor Van
Slyke’s report, which follows, the rate of digestion and proportion of nutriment absorbed
from cooked mussels and squid is compared with that of beef as a standard:

The work outlined was undertaken to determine the comparative rapidity and completeness with
which various sea foods are digested, absorbed, and utilized in the animal organism and the effects of
different modes of preparation and preservation upon the food value. The substances were compared
with beef as a standard. The experimental animal was a fox terrier bitch of 1 21/, pounds weight. While
more valuable results, from a practical standpoint, might be obtained from experiments on men, the
latter could not tolerate for a long time the simple diet used, nor be subject to regular catheterization.
The experiments, furthermore, were for comparison of the behavior of different protein foods under the
same conditions, and it is probable that the foods would rank in the same order when tested in dogs or
in men, although the absolute completeness and rapidity of utilization varies with different species
and individuals.

PRINCIPLES OF METHODS.

The daily rations were so proportioned, from analyzed foods, that the dog obtained just the amount
of protein required to maintain nitrogenous equilibrium. Fats and carbohydrates were also kept
constant. The amount of protein digested was calculated from analysis of the food and feces, the
nitrogen in the latter being ascribed to undigested protein. The rate at which the protein is digested,
absorbed, and utilized is measured by the rate at which its nitrogen is excreted in the urine.

methods in detail.

The dog was brought to nitrogenous equilibrium by feeding on a constant diet of cracker dust,
lard, lean beef, and salt. In the experiments with fish flesh, the beef was replaced by an amount of
steamed fish meat. The fish was cleaned and the flesh steamed immediately after the fish was caught,
in order to prevent autolytic or bacterical changes. The remainder of the ration was the same as
in the beef diet, except the amount of lard was reduced in proportion to the fat content of the fish flesh,
so that the fat content of the ration was kept the same as in the standard beef diet. All foods were
analyzed for nitrogen and fat. On alternate days animal charcoal was mixed with the ration, in order
that the feces from food consumed on successive days might be separated by their colors. In case
the entire daily ration was not consumed, the remainder was fed through a tube.

FOOD VALUE OF SEA MUSSELS.

103

The animal was catheterized immediately before feeding the day’s ration, and at three-hour intervals
thereafter for twelve hours, then again at the end of twenty-four hours after feeding, the bladder being
washed out with 0.6 per cent sodium chloride solution at each catheterization. The nitrogen excreted
in the urine during each interval was determined by Kjeldahl analysis. The urine obtained at each
catheterization, combined with the cage washings in case the dog had urinated during the interval,
was acidified with sulphuric acid, diluted to 500 or 1,000 volumes, and one-twentieth taken for
analysis.

The feces containing the undigested portions of each day’s rations were collected and the nitrogen
content determined. The animal charcoal in the alternate day’s feces made a separation possible,
and the 5 grams of bone ash fed daily insured a well-formed, solid, stool.

It was found that analysis of both food and feces for nitrogen and fat could be made accurately
without preliminary drying in a dessicator. For fat analysis about 10 grams of the fresh material were
ground up with anhydrous copper sulphate until the mixture became a dry, homogeneous powder.
This was extracted for about ten hours with carbon tetrachloride, ground again, and reextracted for
a few hours. Representative samples of flesh for nitrogen determination were obtained by grinding
the flesh as fine as possible in a meat grinder, and taking 2 grams or more for the sample.

The daily diet consisted of 25 grams of fat, 50 grams of cracker dust, and sufficient beef or fish flesh
to bring the total nitrogen of the diet up to the amounts indicated in the table. About three-fourths
of the protein ration was contained in the flesh, the other one-fourth in the cracker dust. To the lard,
cracker dust, and meat were added 5 grams of sodium chloride and 5 grams of bone ash.

After being fed squid for two days, the dog refused to consume completely the rations offered and
was partially starved for several days. During the feeding of raw beef and squid she consumed and
excreted 2.5 grams of nitrogen daily, as indicated in the two lower curves of the figure.

The results are briefly indicated by the following tables and figure :

Table 2. — Showing Results of Metabolism Experiments.

Ration containing —

Raw beef.

Steamed

squid.

Steamed

beef.

Steamed

mussel.

2. 497

■ 423
2. 074
83- 1

2. SOS
. 291
2. 214
88. 4

2 . 085
. 285
1 . 800

86.3

2. 131
• 444
1 . 687
79- I

Nitrogen digested

Per cent nitrogen digested

Ration containing —

Raw beef.

Steamed

squid.

Steamed

beef.

Steamed

mussel.

Nitrogen in ration (grams)

Nitrogen in urine +feces

Nitrogen retained

2. 497
2. 489
+ 0. 01

2- 5°5
2. 48s

+ 0. 02

2. 085
1 . 910
+ 0. 18

2. 131
2. 1 17
+ 0. 01

conclusion.

The above results indicate (table 2) that the protein of the ration containing steamed mussel
was digested somewhat less completely (79.1 per cent) than that of raw beef (83.1 per cent), while the
squid gave higher results (88.4 per cent) than the raw beef. The steamed-beef figures (in table, not
in the figure) are of doubtful accuracy, as a portion of the feces may have been lost, causing the high
figures for digestibility (exceeding those of raw beef, which is improbable) and for nitrogen retention
The digestibility figures indicate only the relative digestibility of the meats fed. A considerable

104

BULLETIN OF THE BUREAU OF FISHERIES.

proportion of the undigested (fecal) nitrogen is due to the cracker-dust protein, which is known to be
less digestible than ordinary flesh proteins. Consequently, in order to determine the digestibility of
the meat proteins alone, a correction must be applied for the undigested vegetable protein. Unfor-
tunately, we lacked time to determine this correction.

The urine curves must be considered in pairs, because the amount of nitrogen given in the raw-beef
and steamed-squid diets was greater than that given later in the steamed-beef and mussels ration.
The beef and squid (upper) curves show that the beef protein was metabolized more rapidly, as the beef
curve rises more rapidly after feeding. The difference is not great, however, and the total amount
of squid nitrogen metabolized and excreted in the urine in twenty-four hours is slightly the greater,
coinciding with the fact that less squid nitrogen was found in the feces. Apparently squid proteins
are digested slightly less rapidly than those of beef, but more completely

The steamed-beef and Mytilus curves show a similar relation, the beef being metabolized more rap-

Fig. i. — Curves showing results of metabolism experiments. Figures on base line indicate number of hours
since feeding. Figures in vertical line at right show number of grams of nitrogen excreted in urine.

idly in the hours immediately following feeding, the Mytilus curve overtaking and passing the beef
curve later, however.

The raw-beef figures are taken from three successive days’ results, the figures for the other meats
from the results of two days’ experiments each. The brief time (less than three weeks) available pre-
cluded longer tests, which would have been desirable, and limited the experiments to those above
reported. They must be regarded as merely preliminaries to a thorough investigation of the problem.

It is clear, from the evidence just presented, that the mussel measures up well to
the standard of digestibility. It agrees well with the consumer and the rate of digestion
and proportion of nutrients supplied to the body approximate very nearly those of
steamed beef.

FOOD VALUE OF SEA MUSSELS.

105

COMPOSITION AND NUTRITIVE VALUE.

The function of food is to build up new tissues and repair them as they are worn
out by use, to supply heat energy for keeping the body warm and muscular energy for
doing work. The nutritive value or degree to which a food material is able to perform
this function depends upon two factors, (1) the ratio of edible portion to refuse and (2)
the relative amounts of nutrients contained in the edible portion. The first of these is
determined by separating the flesh and liquor from the shells and byssus of the mussels,
then weighing them separately and determining the percentage of each present. The
second factor is determined by means of a chemical analysis of the edible portion.

The nutrients sought represent four classes of compounds: (1) Protein, which forms
the nitrogenous basis of blood, muscle, connective tissue, etc.; (2) carbohydrates; (3)
fats, which may be stored up as fat or consumed for fuel; and (4) mineral matters or
ash, which are used chiefly in the formation of bone.

In studying the ratio of edible portion to refuse two sets of determinations were
made. One was based on the examination of fresh or uncooked specimens and the
other on mussels which had been cooked by steam. In the first case the mussels were
weighed after being washed free from dirt. They were then quickly shucked and
“bearded,” the meats and liquor being preserved in separate dishes. What liquor
adhered to the flesh was drained off and added to the other dish. The weights of the
flesh and liquor werp ascertained and recorded. The total weight of the mussels minus
the combined weights of the flesh and liquor was considered the amount of refuse
matter. This method, it will be observed, places the loss due to handling in the refuse
column. The results obtained from the examination of five separate lots of mussels will
be found in the following table :

Table 3. — Showing Proportion of Edible Parts to Refuse in the Sea Mussel.

Determinations from fresh or uncooked material.

Date.

Num-

ber

taken.

Total

weight.

Aver-

age

weight.

Flesh.

Liquids.

Total

edible

portion.

Refuse.

Flesh.

Liquids.

To+al

edible

portion.

Refuse.

1908.

Lbs.

oz.

Ounces.

Lbs. oz.

Lbs.

OZ.

Lbs.

oz.

Per ct.

July 10

1. 68

1 8i

1 6|

1 44

5 4

28. 87

26. 78

55-65

44- 35

July 13

100

i-57

2 13J

2 8

5 s

28. 75

25. 48

54- 23

45- 77

August 8

5°

i-39

I IlV

i h

if^

3 if

25-35

23- 74

49- 09

50. 91

August 26

3 4

1.76

O 9T8

0 io*

3 s

26. IO

29. 00

55- 10

44- 90

August 28

1 1

1. 68

0 5b

0 4b

30. 80

25 . 00

55- 80

44- 20

Total

231

Ilf

i- 57

6 5

5 13!

I 2

2§

27. 79

25- 75

53- 54

46 46

In the second case the total weight, as above, was taken after washing the mussels
free from dirt, but before removing the meats and liquor the shellfish were cooked by
means of steam until the shells began to open. This treatment gives very different
results from those obtained from the raw material, as may be seen in the following:

io6 bulletin of the bureau of FISHERIES.

Table 4. — Showing Proportion op Edible Parts to Refuse in the Sea Mussel.

Determinations from steamed material.

Date.

Num-

ber

taken.

Total

weight.

Aver-

age

weight.

Flesh.

Liquids.

Total

edible

portion.

Refuse.

Flesh.

Liquids.

Total

edible

portion.

Refuse

1907.

Lbs.

oz.

Ounces.

Lbs. oz.

Lbs.

oz.

Lbs. oz.

Lb.

. oz.

Per ct.

August 12

119

1. 34

10 V2

5 'A

21.56

15. 00

36. 56

63. 44

I)o

167

1. 44

2 15

19- 58

7- 50

27 . 08

72. 92

August 13

186

1.38

3 4

1 1

20. 35

10. 54

30. 89

69. 11

192

i-33

3 3

19. 92

1 1 . 7 1

31- 63

68. 37

August 14

204

1. 33

3 8

1 1

20. 58

12.50

33- 08

66. 92

August 15

213

i-35

3 13

1 1

21.18

13- 19

34- 37

65. 63

August 26

180

1 . 42

3 1

I 2

1 1

19- 14

10. 97

30. 1 1

69. 89

August 27

330

1 . 2 1

5 9

22. 25

10. 50

32. 75

67. 2S

August 28

1. 63

1 9 14

I Vi

14 ^

17. 71

5-55

23. 26

76. 74

1908.

July 9

1 . 60

I 13

20. 00

6.89

26. 89

73- 11

July 12

2l8

1 . 70

4 1

17- 52

8. 09

25. 61

74- 39

July is .

106

1 2

1 . 81

2 6

1 1

19. 79

7. 81

27. 60

72. 40

July 16

356

1 . 61

6 9

I 2

1 1

20. 34

7,63

27. 97

72. 03

.luly 30

356

1. 44

5 7

17.26

8.33

2 5 ■ 59

74. 41

August 8

287

1 . 80

4 12

I I

2.5

14. 70

5-99

20. 69

79-31

August 10

212

i- 52

2 15

14- 55

4. 64

19. 19

80. 81

August 11

l8o

1 . 60

2 5

12. 84

4. 16

17. OO

83. 00

August 14

744

1 2

1 . 60

15 12

21. 15

12. 29

33- 44

66. 56

Total

4, 229

399

1.50

75 1

1 12

286

I 2

18. 81

9- 32

28. 13

71-87

A comparison of the two tables reveals a wide difference in the ratios of edible
parts to waste. In case of the raw material it is 53.54 per cent of meat and liquor to
46.46 per cent of refuse. With the cooked material it is 28.13 Per cent to 71.87 per cent.
This great dissimilarity of results is due to two facts. In the first place, cooking
removes considerable water from the flesh and in the second place the opening of
the shells of many of the mussels during the process of cooking causes considerable
loss of the natural liquor. The loss of water and liquor is thus added to the refuse
column and makes the difference between the useful and waste parts appear greater
than it really is. These figures apparently indicate that much loss of food material
results from cooking, but such is not the case. The loss in weight is due almost entirely
to the extraction of water.

A comparison of the mussel with the oyster and long clam on the basis of the rela-
tive amounts of edible parts to refuse will help one to appreciate its real value as a food.
The figures used for this purpose are taken from Atwater (1891) and incorporated in
the following table:

Table 5. — Showing Percentage of Edible Parts and Refuse in the Mussel, Long Clam, and

Oyster.

Kinds of shellfish.

Number
of speci-
mens.

Edible portion.

Refuse

(shells,

etc.).

Flesh.

Liquids.

Total.

Sea mussel

44i

3,383

Per cent.
32. 66
34- 77
9. 81

Per cent.
18. 00
21.78
7- 65

Per cent.
50. 66
56. 55
17. 46

Per cent.
46. 69
4i. 77
81 . 40

Measured by the above standard, the mussel contains about the same proportion
of flesh and liquids as the long clam and about three times as much as the oyster. If

FOOD VALUE OF SEA MUSSELS.

107

the flesh of each species contained the same amount of nutrients we might conclude that
for equal weights of the shellfish the food value of the mussel is about equal to that of
the long clam but three times that of the oyster. This obvious superiority over the
oyster is due to the thin, light shell of the mussel, which stands in sharp contrast to
the heavy, thick shell of the oyster. A consideration of the chemical composition of
these forms, however, will show that the difference in food value between the mussel
and oyster is even greater than is indicated by the above table.

The account which follows is taken from Doctor Alsberg’s personal report to me. In
view of the fact that the methods used in making the analyses differ in some important
particulars from those employed by Atwater (1891), with whose results comparisons
are made, it is necessary to describe them briefly.

In preparation of a sample a large quantity of the mussel meats was ground up in a
meat chopper and the ground-up sample thoroughly mixed. Of this, a small sample
of 50 grams was weighed out into a weighed glass dish. Enough sulphuric acid was
added to make the reaction neutral. As the reaction of the juices of invertebrates
is very alkaline, this is a most important matter. If it is neglected, much nitrogen is
lost as ammonia. This precaution has apparently not been taken by Atwater or any-
one else. Probably Atwater’s figures for oysters are too low for this reason. Doctor
Alsberg’s high nitrogen values are probably in part due to this method. The glass dish
containing the 50 grams of neutral material was then evaporated to dryness on the
steam bath, with care that the reaction remained neutral. Atwater dried in a stream
of hydrogen. There were no facilities for doing this in the present work, but it is thought
that the results are unaffected, except to a slight extent for the fat determinations.

The material thus dried was very difficult to pulverize, partly because of the fat
content, which made it greasy, and partly because invertebrates contain hygroscopic
salts. Therefore the material was boiled out with 95 per cent alcohol until the latter
was colorless. The alcoholic solution was made up to a known volume and analyzed
by itself. The results were added to those obtained from the residue. The sum of the
two gives the figures for the total. The residue from the alcohol was easily ground up
and sampled in an agate mortar. The material for all the determinations was weighed
out at the same time. In addition, about 1.50 grams were weighed in a weighing bottle
and dried at 6o° C. in vacuo over sulphuric acid in a Schmiedeberg drying apparatus. In
this way the total quantity of water was determined and the determinations calculated
accordingly. The water determinations are therefore more correct than those of Atwater.

The fat determinations were done by extracting with carbon tetrachloride (CC14)
in a Soxhlet apparatus. It was not safe to use ether, as Atwater did, because of the
danger of fire in a wooden building. As carbon tetrachloride is a better solvent than
ether, the figures obtained are naturally a little higher than those of Atwater. Another
reason why they are higher is that the material was not dried in hydrogen.

Nitrogen was determined by the Kjeldahl method, which had not been discovered
in Atwater’s time. He used the soda-lime method, which is probably as good.

• Atwater made no determinations of carbohydrates. Inasmuch as the oyster con-
tains much glycogen, an attempt was made to determine glycogen in the mussel. This

io8

BULLETIN of the bureau of fisheries.

was done by Pfliiger’s method in its latest modification. One hundred grams of abso-
lutely fresh material were used and the determination begun at once to prevent the
hydrolysis by enzymes. The purified glycogen was determined in three ways: (i) It
was filtered through a weighed Gooch crucible, dried, and weighed. It was then ashed
and the crucible weighed again. The weight of the ash, which was always under 2
per cent, was then subtracted, and the resulting figures are those given in the table.
(2) The glycogen was then hydrolyzed with dilute sulphuric acid and the sugar deter-
mined titrametrieally with Fehling’s solution. (3) The glycogen was hydrolyzed with
dilute sulphuric acid and the resulting sugar determined in the polariscope.

The figures for flesh calculated on fresh substance do not quite total 100 per cent.
This is probably not due to errors in methods or technique, but to errors of calculation.
Thus the proteins are calculated arbitrarily. It is assumed that all nitrogen is present
as protein, whereas as a matter of fact some is in the form of extractives and some in the
form of fats (lipoids). It is assumed, further, that the proteins of mussels have the
same nitrogen content as those of vertebrates. As they have not been investigated,
this is an arbitrary assumption, and the factor 6.25 may be wrong. Moreover, as some
of the nitrogen is in the fat (lipoids), this figures twice in the tables, once as protein and
once as fat. The crude ash, too, does not quite correctly represent the inorganic sub-
stances of the mussel, because in the process of ashing some is volatilized, while new
phosphoric acid and sulphuric acid are formed from the protein. All these, however,
are errors inherent in all analyses of this nature.

The structure of the flesh of male and female mussels being very different (compare
figs. 2 and 3, pi. xxiii), separate analyses were made of the two sexes. The distinction of
the sexes was based on the color of the mantle, white flesh being called male and red flesh
female. This method of separation is, however, not absolutely accurate. Microscopic
examination revealed the fact that in about 2 per cent of the cases a red mussel might
be a male and a white or cream-colored one a female. The results of the analyses are as
follows :

Table 6. — Showing Composition of Mussels Calculated for Water-Free Substance.

[August 15, 1908.]

Ingredients.

White flesh
(male).

Red flesh
(female).

Average for
white and
red flesh.

In flesh:

Per cent.
9- 35
58. 44

8. 51

13- 61

6. 74

Per cent.
10. 75
68. 18
12.01
9. 41

6. 03

Per cent.

10. 05

63.31

10. 26

11. 51

6.38

3. 62
22. 62
. 28
Trace.

65- 50

9. 19
57- 43
8. 93
9- 97
14. 27

In liquids:

In total edible portion:

food value; of sea mussels.

109

Table 7. — Showing Composition of Mussels Calculated for Fresh Substance.

[August 15, 1908.]

Ingredients.

White flesh
(male).

Red flesh
(female).

Average for
white and
red flesh.

In flesh:

Per cent.
76. 62
2. 44
IS- 25
1 . 98
3- 19

1. 58

Per cent.
76. 18
2. 46
15- 38
3- 10
2. 24

1. 44

Per cent.

76. 40
2. 45
15-31
2. 54
2. 71
i- 5i

95 - 64
. 16
• 99
. 01

Nitrogen

In liquids:

2. 86

83- 27

1. 63

IO. l8

I . 64
1- 74
1. 99

In total edible portion:

Fat, CCh Ext.

The above figures indicate that, for a shellfish, the mussel contains a high percentage
of each of the four classes of food materials and that the white-fleshed individuals (males)
differ considerably in chemical composition from the red-fleshed ones (females), the
latter containing a much higher percentage of protein and fat but less carbohydrate.
This difference is accounted for by the fact that the whole body of the female, during
the spring and summer, is distended with eggs which are rich in yolk material. It is
during this season, therefore, that the mussels are at their best as a food.

A fair idea of the food value of the mussel may be obtained by comparing its fuel
value with those of several standard food materials, e. g., oysters, long clams, and
beef. Tuel value refers to the number of calories of heat equivalent to the energy
which the body is supposed to obtain from 1 pound of a thoroughly digested food
material. The fuel values of various food materials are calculated by using the factors
of Rubner, which, in terms of the English system of weights, correspond to 1,860 calories
of energy for every pound of protein or carbohydrate and 4,220 calories for each pound
of fat.

Table 8. — Showing Comparative Fuel Values of Mussels, Oysters, Long Clams, and Lean

Beef.

Food materials.

Refuse.

Water.

Protein

(NX6.25).

Fat.

Carbohy-

drate.

Ash.

Fuel value
per pound.

Per cent.
46. 69

Per cent.
41. 1
83.3
16. 1
86. 9

Per cent.

Per cent.
0. 8

Per cent.

0. 85

1. 74
• 7

Per cent.

Calories.

140

290

235

140

240

785

10. 18

1 . 64
. 2

1. 99
• 4

Oysters, in shell 0

81.4

1 . 2

Long clams, in shell0

41. 9

49- 9
85.8
55-3

5-o
8. 6

1. 1

i-5

Beef, hind quarter as purchased 0 . . .

16. 6

16. 7

11. 2

. 8

° From calculations of Atwater and Bryant (1906).

I IO

bulletin of the bureau of FISHERIES.

A comparison of the fuel values of the mussel and oyster based on the total weight
of waste and edible portions shows that the value of the mussel as a food is three times
greater than that of the oyster. The ratio between the fuel values of the edible portions
of these two shellfish is more nearly equal, but the mussel in this case is superior to the
oyster by 65 calories per pound. The fuel values of the mussel and long clam are
about the same. Compared with lean beef we might say that 5 % pounds of mussels
in the shell, or 2^4 pounds of meats and liquor in their natural proportion, are equal in
food value to 1 pound of beef.

As a food material, therefore, from the standpoint of chemical composition and
nutritive value, the mussel is far superior to the oyster, is equal to the long clam, and
has about one-third the value of lean beef.

MUSSELS A CHEAP FOOD.

Measured by the fourth standard, economy, we again find the mussel taking high
rank among food materials. It is widely distributed, extremely abundant, and easily
obtained. Mussels abound in the bays and estuaries of our Atlantic coast from North
Carolina northward and on our Pacific coast from Alaska to San Francisco. They
grow in great beds, often acres in extent, on the surface of mud or sand extending out
from between tide marks to several fathoms of water. Plate xxiv, figure 1, is a
view of an exposed mussel bed at Menemsha Pond, Marthas Vineyard, Mass. This
bed is but two years old and represents hundreds of tons of valuable food.
Mussels are also found growing in great abundance out in the deeper waters. On one
occasion in Vineyard Sound, not far from Robinsons Hole, the steamer Fish Hawk
dredged up a beam trawl full of them, a quantity approximating a ton or more. A
resident of Pawtucket, R. I., writes that there are places in Narragansett Bay where a
man could obtain 50 bushels a day for the whole season if he had a partner to receive
and dispose of them. Under these conditions he considers 35 cents a bushel a reason-
able price to ask. The total supply of New York City, which amounts to 75 barrels of
mussels in the shell and 400 gallons of the pickled variety per day, is furnished chiefly
from the bays bordering Long Island. The man who provides nearly this whole
supply informed me that the quantity of mussels is far in excess of the demand.

As has already been shown, the mussel breeds at an almost inconceivable rate
and grows very rapidly. Even if the demand should grow to exceed the supply from
the natural beds it would be an easy matter to meet the increase by means of cultiva-
tion. The methods which may be utilized for this purpose are discussed in another
chapter.

The question of real economic importance to the consumer of food is the ratio
between the cost of a given food and the amount of nutriment it supplies. Milner
(I9°3) groups food materials into three classes: (1) Cheap, those which furnish more
than 1,900 calories energy for 10 cents at ordinary prices; (2) Medium, those which
furnish 800 to 1,900 calories energy for 10 cents; and (3) Expensive, those furnishing
less than 800 calories energy for 10 cents. A bushel of mussels weighs about 70 pounds.

FOOD VALUE OF SKA MUSSELS.

Ill

At 35 cents a bushel the rate would be half a cent per pound, or io cents for 20 pounds.
In table 8 we find the fuel value for each pound of mussels in the shell to equal 140
calories energy. 20X140 = 2,800 calories energy, the amount 10 cents would purchase
at 35 cents per bushel. This, however, is calculated on the wholesale price. The
retail cost would probably be double this amount. Consequently, our fuel value
should be cut in half, making 1,400 calories energy the purchasing value of 10 cents
at retail rates. Thus the calculation on wholesale prices places the mussel in the class
of cheap foods. The calculation on retail prices puts it among the cheaper of the
medium-priced foods, such as beef flank, neck and shank, milk, beans, and turnips.

To thousands of families who live near the coast, the mussels are to be had for the
slight effort required to gather them, and yet up to the present time all this vast wealth
of food has been ignored and wasted. This, too, where families in easy reach of a rich
supply of the shellfish are facing poverty.

PRESERVATION METHODS.

At the present time there is great need for methods of preserving perishable foods
in such a manner as not to injure their palatable flavor and nutritive qualities or greatly
increase the price at which they may be sold to the consumer. Especially is this true
for fishery products, which spoil very quickly after removal from the water. The
decomposition which sets in so rapidly is caused by the presence of bacteria, which
multiply with great rapidity, the rate of putrefaction progressing in direct proportion
to their increase in number.

To preserve fishery products, then, it is necessary to keep them free from the
action of bacteria, and this may be accomplished by eliminating one or more of the
three conditions on which the life and growth of the organisms depend — namely, heat,
moisture, and oxygen. Cold storage deprives the organisms of sufficient heat for
growth, desiccation takes the needed moisture from them, and canning at high tem-
peratures destroys the germs present and, furthermore, excludes the air required for
growth. Antiseptics, such as salt, vinegar, and boracic acid, are employed to prevent
the multiplication of bacteria. All of these methods are applicable to the mussel.

CANNING.

The sea mussel is of all the shellfish particularly adapted for canning. Unlike the
oyster, it remains tender and retains its full flavor when subjected to the high tem-
peratures necessary to prepare it in this way. The process which has been devised as
most feasible is as follows :

The mussels when taken from the collecting boats are rapidly picked over by hand
to eliminate any dead or unhealthy ones which may be present, as well as the coarse
adhering debris. Then they are placed in a cleaning apparatus, such as is shown in
figure 2. It consists of a rectangular box 2 by 2 by 3 feet, which revolves on its long
axis. The ends of the box are of solid yellow pine and are firmly held in place by four
pairs of braces 3 feet long, 2 inches wide, and y2 inch thick. Three sides of the box are

1 12

bulletin of the bureau of fisheries.

inclosed with f ^-inch mesh galvanized wire netting. The fourth side has a door 8 inches
wide, running the length of the box. The door is clamped firmly in place by means of
a lever, which is swung over it. The rest of the side is filled in with parallel strips of
wood placed one-half inch apart. The projecting ends of the axis rest on the walls
of a trough \ % feet deep, in which there is running- sea water. A crank at one end serves
as a means to rotate the cage.

About i bushel of mussels is placed in this cleaning apparatus, which is set in rota-
tion at the rate of 30 revolutions a minute for fifteen minutes. The treatment cleans
off from the shells all clinging sea weeds, sand, and debris, besides breaking open the

Fig. 2. — Apparatus for cleaning mussels preparatory to canning or other preservation process. (Drawn
for the author by Prof. L. C. Harrington.)

shells of dead mussels and washing away the injurious substance contained within them.
In the experimental work this method of cleaning mussels proved very effective. For
cleaning on a commercial scale the device may easily be constructed on larger dimen-
sions and operated by means of steam or water power.

After this treatment the mussels are removed and rinsed off with clean water.
They are placed in a chest and subjected to live steam for from five to ten minutes, or
until the shells begin to open. They are next emptied out into shallow pans to cool
and the natural liquor which has escaped into the chest is preserved in a separate dish.

FOOD VALUE OF SEA MUSSELS. 113

As soon as they are cool enough to be handled, the mussels are shucked and the horny
“beard” removed, the meats and liquor being preserved in separate dishes.

While the liquor taken from the steam chest and that taken from the mussels
during the process of shucking is filtering through a fine-meshed cloth, the mussel meats
are packed in glass jars or bottles. The filtered liquor is brought to a boil and 2 ounces
of salt are added for each gallon. The jars containing the meats are then filled with
the boiling liquid and sealed. To insure complete sterilization, the sealed jars are
placed in a steam chest and subjected to 5 pounds pressure for fifteen minutes. They
are allowed to cool down slowly and when the temperature has fallen to about ioo° F.
they are removed and set aside for future use.

Persons wishing to can mussels for use in their own homes and who lack the facilities
described in this process, may do so by modifying the method in the following way:
After thoroughly cleaning the outsides of the mussels by means of a stiff-bristled brush,
rinse them in clean water and place them in a large, closely-covered kettle with a little
water covering the bottom — about one cup of water to each gallon of mussels. Place
on the stove and bring to a boil, continuing the cooking for about fifteen minutes or
until the top shells have opened. Pour out the liquor that has collected in the bottom
of the kettle and preserve it in a separate dish from the mussels. Shuck the mussels,
being careful to remove the byssus or horny tuft of threads growing out from the base
of the foot. While the liquor is filtering through a fine-meshed cloth pack the meats
in pint or half-pint glass jars of the ordinary household type. To each quart of the
filtered liquor add one heaping teaspoonful of salt and bring it to a boil. Pour the
boiling liquid over the mussel meats, filling the jars to the brim, and then quickly clamp
or screw on the lids. The jars should next be placed in a large vessel, such as a wash
boiler, containing boiling water, and left to boil for at least half an hour. At the end
of this time the vessel with its contents should be removed to the back of the stove
and allowed to cool. As soon as convenient the jars may be removed and the tops
tested to see that they are sealed air tight. Treated in this manner, the mussels ought
to keep for many months and preserve their natural flavor. When desired for use on
the table they may be prepared according to almost any of the methods employed in
preparing the fresh mussels for food.

PICKLING.

At the present time, in the United States, the pickling of mussels is the only form
of preservation in use. As an article of trade they are known only to New York City
and vicinity, one man supplying most of the demand with 400 gallons per day. They
are eaten both by Americans and foreigners. The process for preservation by pickling
involves the use of vinegar and spices in various proportions according to individual
fancies. In my own experience I have found the following formula most satisfactory
in results:

48299° — Bull. 29 — 11 8

BULLETIN OF THE BUREAU OF FISHERIES.

I 14

After thoroughly washing the mussel shells in the cleaning apparatus already
described, the mussels are placed in a steam chest for about ten minutes, or until the
shells have opened. They are then shucked, the liquor and meats being preserved in
separate vessels. Care should be taken to see that the horny filament or “beard” is
removed from the base of the foot. For each quart of natural liquor there is added
1 pint of vinegar, l/2 ounce of allspice, ]/2 ounce of cinnamon, X ounce of cloves, % ounce
of salt, and 1 small red pepper. The mixture is allowed to simmer upon the stove for
fifteen minutes and is then poured over the meats. After standing about twenty-four
hours the meats are removed from the spiced liquor and are neatly packed in bottles
or fruit jars. The liquor after being filtered through a fine-meshed cloth, to remove
the undissolved spices and sediment that is formed, is heated to boiling and poured
over the meats until the jars are brimming full. The jars are sealed air tight and placed
in a steam chest, where they are subjected to 5 pounds steam pressure for fifteen
minutes.

After this treatment they will remain in a good state of preservation for about two
years. If the pickled mussels are desired for immediate consumption, it is not necessary
to seal them up in jars. They may be kept a week or more in open tubs without dete-
riorating. If kept much longer than this, they gradually turn dark and fall to pieces.
A New York dealer told me that he was able to sell pickled mussels in the tub at 35
cents per gallon, but this gave him very little profit.

DRYING.

The preservation of mussels by means of desiccation is a problem to which I
have devoted considerable attention. So far the efforts have been hardly successful
enough to make mention of them in this report. A few words concerning the difficulties
involved in the process, however, and some observations may be of value. The prob-
lem to solve in drying mussels for food is to regulate the process, so that the flavor of
the meats is not impaired nor the appetizing odor lost.

The plan originally employed was to clean the mussels, steam and shuck them by
the method already described, and transfer the meats to an artificial dryer, which con-
sisted of a large chamber, 3 by 5 by 6 feet, tapering off at the top into a flue. Two
drawers with galvanized wire bottoms extended into this chamber. A current of air
was forced by means of a 24-inch fan over a hot radiator into the bottom of the cham-
ber, from whence it passed upward through the meshed drawer bottoms and over the
substance to be dried. The temperature of the air as it passed over the drying flesh
was 50° C., or 1220 F. Material subjected to this treatment dries very rapidly, even in
the very humid atmosphere of Woods Hole, Mass. In from seven to twelve hours
mussel flesh treated thus will lose 70 per cent of its weight. The accompanying table
of 12 experiments indicates that after seven hours’ drying most of the water which it
is possible to extract by this method has been removed.

FOOD VALUE OF SEA MUSSELS.

“5

Table: 9. — Showing Loss of Weight in Mussels Due to Drying.

Date.

Weight of
flesh.

Time in
dryer.

Weight after
drying.

Per cent of
loss.

Per cent re-
maining.

1907.

August 28

Ounces.

10 SA

Hours.

Ounces.

3 K

69. 4

30. 60

August 29

5 y«

79- 5

20. 50

August 30

17 *A

7°- 83

29. 17

1908.

July 9

1 2

7 SA

73- 7i

26. 29

July 10

24 K

6 A

72. 13

27. 87

July 12

64- 04

3596

July 15

a 42

93A

76. 79

23. 21

July 16

105

36 'A

65. 48

34- 52

August 10

1 4 vs

69 95

30. 05

n3/i

68. 24

31- 76

August 26

6 3A

71. 84

28. l6

August 28

7 ^

75. 00

25. OO

Total

499

b i6§

149 3A

69. 99

30. OI

“ Had been salted down 15 hours. 6 Average length of time in the dryer.

The product of this treatment is a brown brittle substance with an unappetizing
look and odor. The appearance is greatly improved by passing the material through
a sausage grinder, which breaks it up into a mass of brown granules. In this condition
it looks well when put up in glass jars or fiber-ware packages. The only remaining
objection to it is an offensive alkaline odor. In attempts to eliminate this disagreeable
quality I have treated both the raw and cooked flesh with salt, with vinegar, and with
hydrochloric acid in various proportions and for various periods of time preliminary to
the drying, but without success. The purpose of using the acid, which was in very
dilute solutions, was to neutralize the alkaline compounds as fast as they were formed.
Dried mussels which had been soaked in a 0.2 per cent solution of hydrochloric acid
for two hours before desiccation were rendered remarkably free from any bad odor.
After being bottled up for a few weeks, however, they acquired the smell so character-
istic of the dried material.

In spite of this offensive property the dried mussel can be used in preparing a very
palatable soup or chowder. A better smelling variety will have to be produced, how-
ever, before there can be a possibility of attaching commercial importance to it.

The chief trouble with this process is that the drying is accomplished at a high
temperature, where chemical changes within the food material are accelerated, causing
the production in large quantities of undesirable substances. This difficulty is removed
by means of an improved method of desiccation devised by Shackell (1909). Briefly,
this consists in freezing the flesh, and drying it, while still in the frozen condition, in a
vacuum. At this low temperature chemical changes practically cease and with the
extraction of moisture a very stable substance is secured which will withstand all ordi-
nary temperatures. Mussel flesh treated by this method shows remarkable properties.
It retains the color and form of the fresh material; it is light and porous and can be
easily crushed between the fingers. In air-tight bottles it may be preserved indefinitely.

bulletin of the bureau of fisheries.

A sample of mussel thus prepared, after having been kept a month, was placed in a
small dish of water. The dried material rapidly absorbed moisture and at the same
time the natural juices dissolved out into the water, giving it the characteristic opa-
lescent color of fresh mussel liquor. The odor was that of perfectly fresh mussels, and
when made into soup the aroma and flavor were those of cooked fresh material. This
method of preservation is ideal but for one reason — the high cost forbids its use com-
mercially. The inventor of the method is working to overcome this disadvantage.

COLD STORAGE.

The mussel is not well adapted to the method of preservation by means of cold
storage. The writer wishes to make this statement with reserve, however, since his
experiments in this respect have been very limited. Attempts to keep mussels fresh in
an ice chest for more than twenty-four hours met with failure. They appeared to
live no longer in the cold than in the open air. Decay did not seem to be retarded by
the lower temperature of the ice box. This fact was a matter of complaint made by a
New York dealer who wished to develop a market for mussels inland. I was informed
that it would be possible to develop quite a trade in mussels if a method for preserving
them in the fresh or living condition could be devised. At present I can only suggest
a probable solution of the problem; that is to reduce them to a freezing temperature
and ship them in a double walled carrier having a vacuum between the walls. The
vacuum being a nonconductor of heat insures the continued low temperature of the
mussels and does away with the surplus weight of ice usually employed in cold-storage
transportation. The mussels preserved in this manner would have to be used almost
immediately after removal from the carrier. Further mention of this method of preserva-
tion will be found in my conclusions and recommendations.

RECIPES FOR COOKING SEA MUSSELS.

CREAMED MUSSELS.

Thoroughly wash the mussels and place them in boiling water until the shells begin to open. Pour
off the water quickly, take out the “ beard” or byssus, and remove the meats from the shell, preserving
the liquor in vl separate dish. For each cupful of chopped meats make one cupful of cream sauce,
which is prepared by melting in a saucepan one tablespoonful of butter and stirring with it one table-
spoonful of flour; cook, being careful not to brown it; then stir in slowly one-half cupful of mussel
liquor and one-half cupful of milk or cream and season with pepper and salt to taste. Continue to cook
until it is thick and creamy, stirring all the time; add the mussels just before serving. Pour the mixture
over small pieces of toast laid on the bottom of the dish.

FRIED MUSSELS.

After thoroughly cleaning the outsides of the mussels boil them until the shells begin to open.
Take out the “ beard” and remove the meats from the shell. Season with salt and pepper, then roll in
cracker or bread crumbs, dip in egg beaten up in milk, and roll again in the crumbs; fry quickly in hot
fat; drain on paper as fast as taken up. Serve hot, garnished with slices of lemon. Have them as free
from grease as possible.

FOOD VALUE OF SEA MUSSELS.

117

MUSSEL CAKES.

Clean and scald the mussels as directed above, beard, and remove the meats. To one pint of
chopped mussel meats add two eggs, one-half cupful of milk, two teaspoonfuls of baking powder, and
a pinch of salt. Stir in enough flour to make the mixture a little thicker than pancake batter and fry.

MUSSEL CHOWDER-

Clean and scald the mussels as directed above, take out the beard, and remove the meats, preserv-
ing the natural liquor in a separate dish. To a quart of the meats take a quarter pound of salt pork;
cut it into small squares and fry to a brown in the bottom of the kettle. At the same time add three or
four sliced onions and cook until the pork is well tried out; then add the mussel liquor, mixed with an
equal quantity of water, and when it comes to a boil add six finely chopped or sliced potatoes and
boil in a closely covered dish until the potatoes are done ; then add the mussels with one quart of boiling
milk, season with pepper and salt to taste, and serve.

MUSSEL CROQUETTES.

Clean and scald the mussels as directed above, beard, and remove the meats from the shell. Chop
up one pint of meats, moisten with a thick cream sauce, add one teaspoonful of chopped parsley and
bread or cracker crumbs sufficient to make the mixture firm enough to shape, season with salt and
pepper. Let the mixture get cold, then shape into croquettes and fry in hot fat, in a frying basket if
available; drain and serve on a hot napkin.

MUSSEL FRITTERS.

Two eggs, one tablespoonful of oil, one cupful of flour, one-half cupful of mussel liquor, pinch of
pepper and salt, tablespoonful of lemon or vinegar, one cupful of chopped mussel. Have the mixture
quite thick and drop from a tablespoon into hot fat and fry until an amber color.

MUSSEL PATTIES.

Cut one quart of scalded mussels into small pieces and stir into one cup'of rich drawn butter based
on milk, season to taste, cook five minutes, fill the patty cases, heat two minutes, and serve

MUSSEL SOUP.

Clean and scald the mussels as directed above, beard, and preserve the meats and liquor in separate
dishes. To one pint of the liquor add an equal quantity of water; season with pepper, mace, and salt,
and boil five minutes. Then put in the mussels, either whole or minced, and boil for five minutes with
the vessel closely covered. Then add a pint of milk thickened with a little flour and butter or fine
cracker crumbs. The addition of a little chopped celery and onion improves the flavor.

ROASTED MUSSELS.

Wash the shells thoroughly with a brush and cold water. Place them on a pan and bake in a hot
oven until the shell opens. Remove the upper shell carefully, so as not to lose the liquor, and arrange
them on plates. On each mussel place a piece of butter and a little pepper and salt. Do not roast too
long.

STEAMED MUSSELS.

To a gallon of thoroughly washed mussels, add one cup of water and boil in a closely covered vessel
for ten minutes or until the mussels on top are well opened. Then pour off the water and place the mus-
sels in a large dish on the center of the table. Serve to each person some melted butter to which may
be added vinegar and pepper to taste. The mussels may be removed from the shell, bearded, and,
held by the foot, dipped into the butter and eaten.

BULLETIN OF THE BUREAU OF FISHERIES.

1 18

The French people are noted for their excellent preparations of mussels for the table.
The characteristic feature of nearly all their methods is to serve them on the half shell.
From Audot’s “La Cuisinere de la Ville et de la Campagne” I have taken the following
recipes :

MUSSELS (ENTRIES).

Choose mussels which are fresh, heavy, and of medium size, scrape and wash them through sev-
eral waters. (In order that one may have no fear of them, it is necessary to cleanse them for five or six
hours in water which is renewed several times. Not only are they able to reject the impurities within
them, but they gain in quality. It is necessary to avoid using them from April to September, during
which time they are apt to be unhealthy.)

A la marinikre. — Having cleaned the mussels well, place them in a saucepan with some white wine,
a glass to 4 quarts, or else a spoonful of vinegar, some slices of carrots, onion, and parsley chopped fine,
thyme, clove of garlic, a little salt and pepper, 2 cloves, and a piece of butter the size of an egg. Place
the saucepan on a good fire, keeping it covered from the first to make the shells open. Stew continu-
ously until the shells have opened, when the mussels are done. From each remove one of the shells
and take out the little crabs which are found in them, but which are not injurious in any way; they are
found present principally during the months of the year which do not contain the letter “r.” When
the mussels have thus been opened, stew them a while (stirring or shaking to prevent them from sticking
to the saucepan) and then turn them into a large, deep dish with a quart of their dressing strained
clear. The remainder of this dressing makes a very agreeable onion soup.

A la pouletle. — Take up quickly some of the prepared mussels (steamed and prepared on the half
shell), as they are called, and make a sauce with a piece of butter, a pinch of flour, a little of their liquor,
and the yolks of eggs, if these are desired. Turn this upon the mussels and serve.

A la bechamel. — Pour over the mussels a bechamel sauce in place of the sauce poulette.

BECHAMEL SAUCE.

Melt a piece of butter (about 1 ounce) and mix well with it a spoonful of flour and some salt and
white pepper. Moisten it with a glass of milk, a little at a time with constant stirring; let it boil, being
continually stirred. At the same time warm over that which you wish to serve with the sauce. To
make it more elaborate, place in a saucepan some butter, slices of onion, a carrot, a bunch of parsley,
some mushrooms, and place it on a fire. Moisten with some boiling milk, adding a little at a time with
constant stirring; add some salt, white pepper, and nutmeg, and stir until it boils. Allow it to cook very
slowly for three-quarters of an hour, then strain it through a colander. In a saucepan make a light-
brown butter sauce w7ith 3 spoonfuls of flour and turn into it the milk broth; let it boil three minutes.

Attention should be called to the fact that Audot’s precaution to avoid eating
mussels between the months of April and September does not apply to all parts of the
world. On our northern Atlantic coast the months between April and September are
the very months when the mussels are best for eating purposes, while during the fall and
early winter they are unfit for use. The explanation of this is that the mussels of France
breed in the early spring while these on our coast breed in the late summer and fall.
After spawning the mussels become sickly and great numbers of them die. A more
general way to state the precaution is: Avoid eating mussels from a given locality dur-
ing the four months following their spawning. At the end of this period they again
become fat and healthy.

FOOD value of sea mussels.

1 19

CULTIVATION OF MUSSELS.

In Europe, where there is considerable demand for mussels as food and bait, it long
ago became necessary to cultivate them artificially on a large scale. Two methods were
devised. One may be termed the buchot system or French method, and the other the
bed system or British method. The buchot system is apparently much the older and
its history, although published in many French and English periodicals, is so interesting
that it ought to be recorded again briefly at this point.

Strange as it may seem, this French system of culture was invented by an Irish-
man named Walton who was the sole survivor from a shipwreck in the Bay of Aiguillon
near the village of Esnandes some seven or eight centuries ago. Authors disagree as to the
exact date. Quatrefages (1854) states that it was in the year 1035, Bertram (1865)
says 1135, while Coste (1883) puts it at the close of the year (1235). Walton was kindly
received by the French fishermen, with whom he decided to make his home, although
the prospects of making a good living were not very bright.

Up to the time of Walton’s arrival the inhabitants of the coast had been unable to get
much sustenance from the sea, but the newcomer was ingenious and was not long in origi-
nating a means for earning a livelihood from this source. His first step was to explore
an immense lake of mud which was in the locality and there observing that large num-
bers of land and sea birds were in the habit of skimming over the water at twilight, he
determined to catch them as an object of trade. For this purpose he devised a large
net, the “alluret,” which was between 330 and 430 yards long and 10 feet in height,
fastened in a vertical position to stakes driven into the mud to a depth of 3 or 4 feet.
Birds flying into its meshes were entangled and held securely. Shortly after beginning
his bird-catching business, Walton discovered that young mussels in great numbers were
collecting on the submerged stakes of his net. He also observed that mussels sus-
pended for some distance over the mud grew to a larger size and were better flavored
than those upon the mud. He experimented by putting down many more stakes,
which in turn became covered with growing colonies of mussels. Continuing his experi-
ments he was soon convinced that the young of native mussels could be easily gathered
and profitably raised in artificial reservoirs.

The buchot system of mussel culture that was finally established by Walton is still
followed and has proved a lasting reward and blessing to that locality, where at the pres-
ent time buchots extend for miles along the coast and give support to several thousand
inhabitants. In 1905 the village of Esnandes alone marketed 215,253 bushels of mussels,
valued at $112,433. The total number of mussels cultivated on the French coast in
1905 is estimated at 425,492 bushels, valued at $222,439.

Walton’s buchots, or wooden inclosures for the artificial rearing of mussels, were
made V shaped, with the apex pointing out to the sea, the purpose of this arrangement
being to protect the structure from the destroying action of the wind, waves, and ice.
Each wing of the V consisted of a row of stakes placed about 2 feet apart and interlaced
with a meshwork of flexible willow or chestnut branches some 12 to 18 feet long and

120

bulletin of the bureau of fisheries.

2 inches in diameter at the larger end. The stakes were trunks of trees, J to i foot in
diameter and from 12 to 15 feet long, driven into the mud for about one-half their length.
The meshwork covered the stakes to within 8 inches of the bottom, the space being left
to allow free circulation of water, so as to prevent the deposition of mud at the base of
the stakes. Bach horizontal line of branches was tightly woven to the stakes to pre-
vent slipping up or down. They were arranged about 20 or more inches apart, because,
if brought together closer than that, they were apt to collect mud and cause deposits
that would interfere with navigation and perhaps seriously injure the apparatus itself.

The length of wings to a buchot at any particular place depended, as now, on the
nature of the bottom on which they were constructed. At present they occupy about
one-fourth of the distance between the extreme limits reached by the water at high and
low tides. In the Bay of Aiguillon they are now constructed about 250 yards long, and
according to Herdman (1894), who has made an extensive study of this region, are no
longer arranged in the V form, but in parallel rows about 30 yards apart at right angles
to the shore. The buchots are practically made up of two divisions, one for collecting
spat and the other for the growth and fattening of the mussels.

Five series of buchots may be included in these two divisions: (1) Buchots d'aval,
(2) buchots batisse, (3) buchots du bas, (4) buchots batards, and (5) buchots d’amont.

The buchots d’aval are out in the deep water, sometimes 3 miles from high-water
mark, and are exposed only at the lowest tides. They are composed merely of solitary
stakes placed about 1 foot apart. They serve to catch the spat and constitute a most
favorable place for the early growth of the mussels, since it is necessary for the
young to be protected from long exposure to the sunlight or extreme cold. The spat
collects on these stakes during February and March. By July the young mussels have
attained the size of a haricot bean.

At this time the seed mussels are scraped off the piles by means of hooks fastened
in a handle, are collected in baskets, and transferred to the next zone of weirs, the buchots
batisse, toward shore and ordinarily uncovered after high tides. The parcels of young
mussels are fastened by means of old netting to the branches, where, before the netting
decays away, they become firmly attached by their byssal threads. When the mussels
have grown so large as to be crowded on the wickerwork, they are thinned out by removing
the larger ones to the next higher buchots, and so on from one section to the other, each
time transferring the mussels nearer the shore. The mussels are attached by the same
operation already described, but are not wrapped so carefully since their size is such as to
enable them to be more securely fastened without help of the netting. The work of
transferringfromone buchot toanother goes on dayand night whenever low tide permits it.

After about one year’s treatment under these conditions the mussels attain market-
able size, which is between if and 2 inches in length. Before being offered for sale, those
that have reached the desired size are transplanted to the highest row of buchots, the
buchots d’amont. In this location, although left dry twice each day, they thrive well
and can be easily handled when desired for market. The mussels on these upper rows
become inured to exposure and consequently keep longer and fresher than those from

FOOD VALUE OF SEA MUSSELS.

I 2 I

the lower rows. The poorest of cultivated mussels are considered superior to the best
mussels grown under natural conditions.

To traverse the soft mud from one buchot to the other Walton devised the “aeon,”
a characteristic mudboat still used by the bucholeurs. Herdman (1894) describes it as
follows :

The “aeon” is composed of a piank forming the bottom and bent up in front to make a flat prow.
The sides and stern are each made of one piece of wood, sometimes the sides are of two planks each.
The size is 9 or 10 feet in length, from 2 feet to 2 feet 6 inches wide, and about 1 foot 6 inches deep.
There is a shelf at the stern, a narrow thwart close to the bow, and a small wooden Stool in the middle
of the floor; these with a wooden paddle and a short pole complete the equipment. The boatman in
using the “aeon” faces the bow, grasps the sides about the middle firmly with both hands, rests his
left knee on the floor of the boat, and putting his right leg (encased in a long sea boot) over the side,
he plunges it into the mud and pushes it onward. He is able to propel it at a great rate over the soft
mud, and when he gets to a channel of water where the “aeon” floats he works with paddle or pole
until he again reaches mud and is able to use his foot.

The British method of mussel culture, briefly, is to collect young mussels from salt
water and transfer them to artificial beds in favorable localities. These are generally
situated in estuaries where the water is brackish and where they are not exposed at
low tide, both of which conditions are supposed by many to favor growth and fattening.
Others believe that the presence of fresh water is injurious to the young shellfish and of
no advantage to the full-grown individuals. To support their views they point to the
large beds of healthy, uniform-sized individuals in regions far removed from the influence
of fresh water. Harding (1883) believes that the spat will not mature in anything but
pure sea water, but that for fattening full-grown mussels brackish water of the density
1. 014 is most suitable. It has been estimated that the average yearly yield of an acre
of such mussel beds is 108 tons, worth at least $262.

Careful cultivators observe several rules in planting mussels. They may be planted
on almost any natural bottom, but rich estuarine flats where there is plenty of sand and
gravel covered with mud rich in diatoms, infusoria, and spores of algae is considered the
ideal situation. They are placed in positions where they are not exposed to dangers from
floods, gales, shifting sands, or frost. The beds are so placed that they will not be un-
covered long at low tide nor where silt is likely to deposit upon them. Should this evil be
discovered the bed is immediately transplanted to a better situation. In planting the
beds care is taken not to place the individuals so close together that one will come to
lie on another and thus cause a too crowded condition.

For collecting the mussels a rake or dredge is used, the former instrument being
considered better than the latter for the reason that it does not crush the shells nor cause
sand to shift over the bed. In size it has a breadth of about 18 inches, with the teeth 1
inch apart. It is fixed to a pole 20 to 25 feet long and has a wire net bag behind it for
holding the catch. The large and small mussels are separated by means of a riddle,
which is an instrument having a i-inch iron mesh. The bunches of various size mussels
are first separated by hand and then sifted, or riddled. The large and small mussels
thus divided are then placed in separate beds or the large ones utilized for bait.

122

bulletin of the bureau of fisheries.

Other methods of myticulture are followed in certain localities. Goode (1887),
describing some of the European methods, says:

In the North Sea these [spat collectors] consist of large numbers of trees, from which the smaller
branches have been cut, and which are planted in the bottom of the sea at such a distance from the
shore that their upper portion is partially laid bare at low water. After four or five years they are
raised, stripped, and replaced by others. In the Bay of Kiel, Germany, alone about 1,000 of these trees
are annually planted and about 1,000 tons of mussels are brought on the market. Bad seasons occur,
however, both with respect to quality and quantity, owing to various causes. In the Adriatic the
mussels are raised on ropes extended between poles rammed into the ground. The ropes are raised and
stripped once in eighteen months.

The question now arises, Which is the better method for artificially propagating
mussels on our coast ? This depends on two factors; (1) the quality of mussels produced,
and (2) the actual expense of propagation as compared with the financial return.
Though I unfortunately can not answer this question now, I can throw a little light on
it from the experience of others. In France, where labor is cheap, the buchot system
is most profitable, while in England, where the cost of labor is much higher and where
favorable localities for buchot culture are few, the bed system has to be employed.
That the buchot method of culture is not practicable for the Scottish coast is very
evident from the extensive report of Fullarton (1891), whose conclusion I quote:

The buchot experiment, therefore, does not promise to yield in Scotland the same good results as
in France. This is due to the character of the mud along our shore, to the climatal conditions of our
Scottish waters, and the influence of these on animal life. But the financial aspect of the question, as
shown above, is absolutely fatal to the system. I can not conceive what modifications of the buchot
system would be likely to yield results which would benefit the fishermen of Scotland, nor mitigate in
any important degree the mussel famine; while the bed system only requires to be developed in suitable
localities in order that fishermen may obtain an ample supply of bait at a cheap rate and on sound
financial principles.

Calderwood (1895) states that the buchot system of culture has been tried on a small
scale at five different places in Scotland, and in every case was a failure. At Little
Ferry the mussels were washed from the structures by gales; at Tain one buchot was
covered with shifting sand, while another erected in an unfortunate position yielded
little return. At Inverness the cost of handling the mussels was found prohibitive
and at Montrose the system was found unsatisfactory because the mussels fell from the
laths, which were used instead of branches. Where the cost of building material and
labor are high, the buchot system will be found unprofitable.

Herdman (1894) believes that mussels grown on buchots are no better than those
grown on beds, and thinks the buchot system is necessary only in localities where the
mud is soft and so constantly depositing as to prohibit a bed of mussels from being estab-
lished. Lebour (1907), describing the mussel beds of Northumberland, believes that
the bed system is the only suitable method of cultivation on the coast and that the
buchot system is not a practical one to apply even at Budle Bay and Holy Island,
which regions are best adapted for their use.

In view of the facts just stated, and especially in consideration of the high cost
of building material and of labor in the United States, the prospects are very poor for

FOOD VALUE OF SEA MUSSEES.

123

successfully cultivating mussels by the buchot method on our shores. No serious
objections having yet been found to the bed system, we are left to utilize that method
with better hopes of success, unless in the meantime a better method is devised.

POISONOUS MUSSELS.

Mussels, like oysters, clams, and other shellfish, are subject to contamination from
parasites, bacteria, and the ptomaines generated by these, which render them a dan-
gerous food unless selected with proper care. Cases of serious illness from eating
poisonous mussels are known and a number of persons have died from the effects. The
same is true of oysters and clams, and inasmuch as the symptoms in all the cases are
similar, there is nothing here to indicate that the mussels are not just as safe a food
as the other shellfish when gathered with the same precautions. If they are collected
from pure water and eaten in a fresh condition, they are a wholesome food. It some-
times happens, however, that the individual is peculiarly susceptible to poisoning from
shellfish, and such persons I would advise to abstain from eating them.

The most common cases of poisoning from mussels and other shellfish are due to
ptomaines, which are poisonous substances resulting from the action of micro-organisms
upon the animal tissues. Their formation usually, although not always, accompanies
putrefaction and they are said to be most abundant in its early stages. It is therefore
safest to prepare for the table only shellfish that are in a healthy, living condition.
Dead mussels should never be purchased. Good specimens are free from any stale
odor and do not remain with the shells open after being slightly irritated. They defy
all efforts to open their shells until the muscle which holds them shut is cut.

Dangerous intestinal troubles, followed by eruptions on the skin, have been known
to result from eating apparently fresh mussels. Various explanations have been offered
to account for these effects. Goode (1887) states that the Alaskan Indians, recognizing
this fact, eliminated it by removing the byssus or beard whenever it had a greenish
color, which was a sign that the animal had been feeding upon poisonous material.
Better evidence, however, shows that these evil effects come rather from mussels which
grow in impure waters, and that the injurious qualities lie in the liver rather than the
byssus.

In the year 1885, at Wilhelmshaven, Germany, a large number of people were taken
seriously ill after eating the sea mussel, Mytilus edulis, gathered from the harbor of that
place. Several died from the effects. The symptoms of the poisoning were of three
kinds, (1) a swelling in the head and abdomen, with the appearance of red spots on the
body; (2) diarrhea, cramps, and prostration; and (3) paralysis.

A careful study of the conditions revealed that the water from which the mussels
were taken was stagnant because of the inclosing breakwater, which cut off the effects
of the tides. Although no sewage emptied into the harbor and ships were forbidden
from dumping refuse into the water, the stagnated water was so impure that its effect
upon animal life was highly injurious. Fishes that found their way in through the sluice
gates soon became so sluggish that they could easily be caught by hand. Eels were

124

BULLETIN OF THE BUREAU OF FISHERIES.

observed to lose almost all their vitality during the summer. Mussels from these waters,
when cooked and fed to rabbits, acted as a most virulent poison, killing them in from
two to ten minutes. If the mussels were transferred to places where currents of pure
water could flow over them they lost all their poisonous properties; and, on the other
hand, if harmless mussels were transferred from outside waters to the harbor they
acquired poisonous qualities in less than two weeks.

Virchow (1886) and Wolff (1886) affirm that the poison was not the result of any
decomposition and that the mussels had no external signs of disease. Wolff’s experi-
ments indicate that the liver is the sole source of the poison. Inoculations from that
organ into rabbits and guinea pigs were fatal in every case in from two to twenty min-
utes, while inoculations from other parts were without effect. He believes that the
poison originated in the liver and was not due to the absorption of copper salts, as
popularly believed.

Another record of a serious case of poisoning from the eating of mussels by a party
of Alaskan Indians is briefly mentioned by Dali (1870) and Petrol! (1884). In response
to a request for further details of the incident Doctor Dali wrote me the following story,
which is amplified somewhat from notes gleaned from the references just cited: The
Sitkan natives, being able to get better prices from the Hudson Bay Company, refused to
trade with Baranoff, the Russian director of Alaska. Baranoff therefore resorted to
importing, on a sailing vessel from Unalaska and Kodiak, a large number of Aleut
hunters with their skin canoes, to take sea otter in the islands of the Sitkan Archipelago.
In the year 1799 a party of about 200 camped on the shores of the strait separating
Baranoff from Chichagof Island, where the tides are great and at low water expose great
numbers of mussels. Being accustomed to eat them at home, the Aleuts gathered a
quantity of mussels and feasted upon them. In a few hours they were taken violently
ill, and 150 died within a day or two. This incident gave rise to the name Peril (in
Russian, Pogibshi) Strait, which name it bears to this day. Mussel poisoning in this
region is known to have occurred on other occasions and is supposed to be due to the
ptomaines developed in the liquor of the mussels exposed to the sun. Doctor Dali was
informed by the Aleuts that specimens not actually out of water were always safe.

In Audot’s “La Cuisinere de la Ville et de la Campagne,” page 677, a paragraph is
devoted to the symptoms and treatment of mussel poisoning. A free translation of it
is as follows :

The true cause of the poisoning produced by mussels is not yet known, but it is a mistake to attribute
it to the presence of the small crabs which are found in their shells. The opinion more generally accepted
to-day is that the mussels, by attaching themselves to the bottoms of ships sheathed with copper,
absorb a certain quantity of verdigris, which produces the poison causing indigestion. Whether this
is so or not, the use of these mollusks sometimes leads to symptoms of very serious poisoning, of which
the more common are: A sharp pain in the region of the stomach, violent cramps, severe contractions
of the chest, an alternating quick and slow pulse, a redness and swelling of the face, an eruption of little
red spots upon the skin, cold sweats, and oftentimes convulsive movements and delirium.

When these symptoms manifest themselves it is necessary to combat them promptly by employing
an emetic (2 grains of emetic in a glass of tepid water taken several times at six-minute intervals), and

FOOD VALUE OF SEA MUSSELS.

125

when a sufficiently long time has elapsed since the ingestion of the mussels, follow the emetic with a
purgative such as 60 grams of caster oil in a cup of light bouillon. If the symptoms continue in spite
of these means, give the patient some mucilaginous drink and call a doctor.

The foregoing account would probably frighten the average person from ever
attempting to use mussels as an article of food. Careful inspection, however, will
reveal the fact that the mussels which have caused serious illness came either from
impure waters or had been exposed to the heat of the sun so long that ptomaines had
time to form in the liquor within their shells. Mussels taken from pure water which
has free circulation have never been known to produce injurious effects when eaten.
A New York dealer who has been selling mussels for years has never known of a case
of poisoning from them. Nevertheless, too much emphasis can not be given to the
fact that care must be exercised in choosing proper localities for the cultivation and
collection of mussels for market. They must be sold to the consumer in a perfectly
fresh condition or serious results will be likely to follow.

SUMMARY, CONCLUSIONS, AND RECOMMENDATIONS.

1. The sea mussel, Mytilus edulis Linnaeus, is not utilized as a food to any extent in
the United States outside of the vicinity of New York City.

2. As a food material it is superior to many articles which are commonly eaten.
Scores of persons have pronounced it to be equal in flavor, or even superior, to the oyster;
it is easily digested, has high nutritive value, and is exceedingly abundant and general
in its range. Especially for persons living on the coast it is an excellent cheap food.

3. Along most of our eastern coast the mussel is in season for food purposes when
the oyster is out of season.

4. The mussel is well adapted to preservation. When canned or pickled it will
retain its natural flavor for months.

5. The mussel breeds at a prolific rate, it develops rapidly, requires less special
conditions for growth than the oyster, and may therefore be easily cultivated.

6. The only difficulty in the marketing of mussels for food purposes is that they
spoil quickly after being removed from the water. It is necessary to use them within
twenty-four hours after they are collected or ptomaine poisoning may result. To insure
one’s self against illness from eating them, the mussels must be taken from water that
is pure and subject to the constant circulation of tidal currents.

7. Other important ways for utilizing mussels are as bait for the fisheries and as
fertilizer for soil on which onions and carrots are to be raised.

In view of these facts it is clear that the mussel beds of our eastern and western
coasts constitute a valuable food resource of the nation which so far has not been devel-
oped. The natural beds alone are capable of supplying wholesome food to thousands
of persons at the expense of a little trouble to collect the mussels and to hundreds of
thousands more people, through the markets, at a moderate price. It is possible to
develop an industry in the marketing of mussels which may surpass even that of the
oyster and at the same time have no injurious effect upon the oyster trade. The success

126

bulletin of the bureau of fisheries.

with which mussels may be canned and pickled promises a good future for such a branch
of the business.

The author recommends (i) that the facts set forth in this paper be made known
to the packers of marine food products and widely advertised among the fishing popu-
lation of our northern Atlantic and Pacific coasts; (2) that investigations be instituted
to determine a method for preserving mussels in a fresh living condition long enough to
permit their being readily shipped and sold at the inland markets, and the further investi-
gations on methods for preserving mussels by canning, pickling, etc., which will make
it possible to transport to long distances without being broken or otherwise injured
should be continued; and (3) that a detailed study of the life history of the mussel be
made as of the oyster. The solution of these problems, it is believed, will help to develop
a new and profitable branch of fisheries industry.

LITERATURE.

Allen, E. J., and Todd, R. A.

1902. The fauna of the Exe estuary. Journal Marine Biological Association, vol. 6, no. 3, p. 295-
343-

Anderssen, Joakim.

1880. The fishery exhibition in Philadelphia in 1876. Report U. S. Commissioner of Fish and
Fisheries for 1878, p. 47-71.

Atwater, W. O. /

1891. The chemical composition and nutritive values of food fishes and aquatic invertebrates.
Report U. S. Commissioner of Fish and Fisheries for 1888, p. 679-868.

Atwater, W. O., and Bryant, A. P.

1906. The chemical composition of American food materials. (Corrected Apr. 14, 1906.) Bulle-
tin No. 28, U. S. Dept, of Agriculture.

Bertram, J. E-

1869. The harvest of the sea, 2d ed., p. 40-417. London.

Calkins, Gary N.

1902 Marine Protozoa from Woods Hole, Mass. Bulletin U. S. Fish Commission, vol. xxr, 1901,
p. 415-468.

Coste, M.

1883. Report on the oyster and mussel industries of France and Italy. Report U. S. Fish Com-
mission for 1880, p. 825-883.

Dall, William H.

1870. Alaska and its resources. Boston.

Fraiche, Felix.

1883. A practical guide to oyster culture, and the methods of rearing and multiplying edible
marine animals. Pt. v. — Cultivation of mussels. Report U. S. Commissioner of Fish
and Fisheries for 1880, p. 810-818.

Fullarton, J. H.

1891. On buchot mussel culture and the buchot experiment at St. Andrews. Ninth Annual
Report of Fishery Board for Scotland, pt. 111, for year 1890, p. 212-221. Edinburgh.
Fullarton, J. H., and Scott, T.

1889. Mussel farming at Montrose. Seventh Annual Report of Fishery Board for Scotland,
P- 327-34U pk vii.

Ganong, W. F.

1889. The economic molluska of Acadia. Reprinted from Bulletin no. viii. Natural History
Society of New Brunswick. St. John, N. B.

FOOD VALUE OF SEA MUSSELS.

127

Goode, G. Brown.

1884. The fisheries and fishery industries of the United States. Sec. 1, Natural history of aquatic

animals, 709 p. — U. S. Fish Commission, Washington.

1887. The fisheries and fishery industries of the United States. Sec. v, vol. 11, History and
methods, Mussel fishery, p. 615-622. U. S. Fish Commission, Washington.

Goued, A. A.

1870. Report on the invertebrata of Massachusetts, 2d ed., edited by W. G. Binney. vin+524 p.,
12 pi. Boston.

Harding, Charles W.

1883. The utilization of localities in Norfolk and Suffolk suitable for the cultivation of mussels

and other shellfish. Bulletin U. S. Fish Commission, vol. 11, 1882, p. 83-88.

Herdman, W. A.

1894. Report upon the methods of oyster and mussel culture in use on the west coast of France.
Report for 1893 of the Lancashire Sea-Fisheries Laboratory, p. 41-80, pi. i-m.

King, William.

1891. Mussels and mussel culture. Northumberland Sea Fisheries Committee, p. 1-8. New-
castle-on-Tyne.

Lebour, Marie V.

1907. The mussel beds of Northumberland Sea Fisheries Committee. Report on the Scientific
Investigations for the year 1906, p. 28-46. Newcastle-on-Tyne.

M’Intosh, W. C.

1885. Notes from the St. Andrews Marine Laboratory (under the Fishery Board for Scotland).

I. On the British species of Cyanea and the reproduction of Mytilus edulis Linn. Annals
and Magazine of Natural History, vol. xv, p. 148-152.

Milner, R. D.

1903. The cost of food as related to its nutritive value. Reprint from Yearbook of U. S. Dept
of Agriculture for 1902, p. 387-406.

Moore, H. F.

1907. Survey of oyster bottoms in Matagorda Bay, Texas. Bureau of Fisheries Document No. 610.
86 p., 13 pi., 1 chart.

Peck, J. I.

1894. On the food of the menhaden. Bulletin U. S. Fish Commission, vol. xm, 1893, p. 113-126,
pi. 1-8.

1896. The sources of marine food. Ibid., vol. xv, 1895, p. 351-368, pi. 64-71.

Petroff, Ivan.

1884. Report on the population, industries, and resources of Alaska. House of Representatives,

Miscellaneous Document for 2d sess. of 47th Congress, 1882-83, vol. xm, no. 42, pt. 8.
Quatrefages, A. DE-

1854. Souvenirs d’un Naturaliste. Paris.

Scott, A.

1901. Note on the spawning of the mussel. Ninth Report of the Lancashire Sea Fisheries Labora-
tory for 1900, p. 36-39. Liverpool.

Shackell, L. F.

1909. An improved method of desiccation with some applications to biological problems. Journal
of Physiology, vol. xxiv, no. in, p. 325-340.

Simmonds, P. L.

1879. Commercial products of the sea. vm-t-484 p., illus. New York.

Verrill, A. E-, and Smith, S. I.

1873. Report upon the invertebrate animals of Vineyard Sound and the adjacent waters, with
an account of the physical characters of the region. Report of U. S. Fish Commission
for 1871-72, p. 295-778, pi. i-xxxviii.

128

BULLETIN OF THE BUREAU OF FISHERIES.

Virchow, Rud., and LohmeyEr, Carl; Schulze, Fr. Eilk., and Martens, E- v.

1885. Beitrage zur Kenntnis der giftigen Miesmuscheln. Archiv fiir pathologische Anatomie und
Physiologie und fiir klinische Medicin, bd. 104, p. 161-180.

Wolff, Max.

1885. Die Localisation des Giftes in den Miesmuscheln. Archiv fiir pathologische Anatomie und
Physiologie und fiir klinische Medicin, bd. 103, p. 187-203.

1885. Die Ausdehnung des Gebietes der giftigen Miesmuscheln und der sonstigen Seethiere in
Wilhelmshaven. Ibid., bd. 104, p. 180-202.

Williamson, H. Charles.

1907. The spawning, growth, and movement of the mussel ( Mytilus edulis Linn.), horse mussel
{Modiolus modiolus Linn.), and the spoutfish {Solen siliqua Linn.). Twenty-fifth Annual
Report of Fishery Board for Scotland for 1906, pt. in, p. 221-254, ph xvi.

Wilson, John.

1887. On the development of the common mussel ( Mytilus edulis Linn.). Fifth Annual Report
of Fishery Board for Scotland for 1886, p. 247-256, pi. 12-14.

Wolle, Francis.

1894. Diatomaceae of North America, xm-)- 15+47 p., 112 pi. Bethlehem, Pa.

Bull. U. S. B. F., 1909.

Plate XIX.

1. — Interior surface view of the mantle of a male mussel. X 10.

2. — Interior surface view of the mantle of a female mussel. X 10.

3. — Lateral view of a mussel with the shell and mantle of one side removed. Slightly enlarged.

4. — Lateral view of a female mussel with the shell and mantle of one side and the foot, gills,

and abdomen removed to show the main canals of the genital system. Slightly enlarged.
Abbreviations: A, abdomen; AAd, anterior adductor muscle; AR, anterior retractor muscle;
By, byssus; F, follicle containing male genital products; Ft, foot; G, gills; GC, genital
canals; GP, genital papilla; L, liver or digestive gland; LP, labial palps; M, mantle; Mth,
mouth; O, ova remaining in the mantle after spawning (4CC); PAd, posterior adductor
muscle; PM, pallial muscles; PR, posterior retractor muscles; S, shell; U, umbo.

Organisms constituting the food of mussels. X 1,000. Diatomaceae (modified from Wolle).

1. Biddulphia rhombus (Ehrenberg) W. Smith.

2. Amphora proteus Gregory.

3. Tabellaria fenestrata Kiitzing.

4. Surirella ovalis var. ovata Brebisson.

5. Rhabdonema adriaticum Kiitzing.

6. Navicula didyma Ehrenberg.

7. Navicula lauceolata Kiitzing.

8. Navicula lyra Ehrenberg.

9. Rhabdonema arcuatum Kiitzing.

10. Navicula splendida var. puella Ad. Schmitz.

11. Biddulphia favus (Ehrenberg) H. V. H.

12. Actinoptychus undulatus Ehrenberg.

Bull. U. S. B. F., 1909.

Plate XXI.

Organisms constituting the food of mussels. X 900. Diatomacese (modified from Wolle).

13. Nitzschia sigma var. sigmatella Grunow. X 114.

14. Melosira sculpta Kiitzing.

15. Nitzschia sigma Grunow.

16. Grainmatophora marina Kiitzing.

17. Rhizoselenia setigera Brighter. X 38.

18. Pleurosigma balticum W. Smith.

19. Pleurosigma elongatum W. Smith.

20. Pleurosigma decorum W. Smith.

21. Stephanopyxis appendiculata Ehrenberg.

22. Synedra gallionii Edirenberg.

23. Hyalodiscus subtilis Bailey.

24. Pleurosigma angulatum W. Smith.

25. Coscinodiscus excentricus Ehrenberg.

iDiinTiiingu

■

■I

Bull. U. S. B. F., 1909.

Plate XXII.

Organisms constituting the food of mussels. Protozoa. (All figures except 7 after Calkins.)

1. Exuvisella marina Cienkowsky. X 780.

2. Glenodinium compressa Calkins. X 822.

3. Ceratium fusus Ehrenberg. X 315,

4. Distephanus speculum Stohr. X 960.

5. Exuvigella lima Ehrenberg. X 780.

6. Peridinium divergens Ehrenberg. X 636.

7. Prorocentrum micans Ehrenberg. X 375-

8. Tintinnopsis davidoffi Daday. X 354.

9. Tintinnopsis beroidea Stein. X 900.

Bull. U. S. B. F., 1909,

Plate XXIII

Bull,. U. S. B. F., 1909. Plate XXIV.

i- — A mussel bed at Menemsha Pond, Marthas Vineyard, Massachusetts, exposed at low tide.
( Photographed by Dr. R. W. Miner.)

2. — Dredging for mussels. This vessel operates on the ocean and bays from Princes Bay to Fire Island, and
gathers from 200 to 250 bushels a day. (Photograph by courtesy of Mr. George A. Carman.)

Bull. U. S. B. F., 1909.

Plate XXV.

1. — A heap of mussel shells, the result of a few days’ work. (Photograph by courtesy of Mr. George

A. Carman.)

2. — A heap of shells from mussels which have been pickled for the New York market. The shells are
used as cultch for seed oysters. (Photograph by courtesy of Mr. George A. Carman.)

THE MIGRATION OF SALMON IN THE COLUMBIA RIVER

By Charles W. Greene, Ph. D.

Professor of Physiology and Pharmacology , University of Missouri

48299° — Bull. 29 — ii-

129

CONTENTS.

Page.

Established facts and unsolved problems 131

Principle and method of experiment 133

Marking tags and tools 134

Conditions and details of process 134

Discussion of technique 136

Little injury to fish in handling 137

Effects of marking on migration 138

Detailed results of experiment 139

Careers of individual salmon retaken 142

Chinook salmon 142

Silver salmon 143

Steelheads 144

Migration speed 145

Summary of conclusions 148

130

THE MIGRATION OF SALMON IN THE COLUMBIA RIVER.

By CHARLES W. GREENE, Ph. D.,

Professor of Physiology and Pharmacology, University of Missouri.

J-

ESTABLISHED FACTS AND THE UNSOLVED PROBLEMS.

The life history of the anadromous fishes is one of the most interesting subjects
in biology. The detail of facts surrounding the migration of the young from the fresh
water to the sea and the migration of the adults to fresh water for spawning purposes
are indeed little enough known of themselves. How much more shrouded in obscurity,
therefore, must be the causes operating during these migrations. The United States
Bureau of Fisheries has never ceased in its efforts to untangle this thread of piscatorial
history.

In the instance of the Pacific coast salmon of the genus Oncorhynchus , thanks to the
labors of Evermann, Gilbert, Meek, Rutter, Chamberlain, and others, the following
general facts are now established within a reasonable degree of certainty:

i. The young of the species of Oncorhynchus , which have been hatched in the fresh-
water streams, migrate to the sea, where they can secure an abundance of food during
their developmental period. Evermann® in 1894 and 1895 observed many young
O. tschawytscha and O. nerka in the Salmon River headwaters in Idaho. He says: “We
are not yet able to say just when the young salmon leave the waters where they were
hatched and begin their journey to the sea, but it undoubtedly occurs between September
of the first and July of the second year following that in which they were spawned.
Eater Rutter 6 followed the downward migration of young salmon in the Sacramento
River, California. He found that young salmon fry “begin their down-stream migra-
tion as soon as they are able to swim.” They reach the estuary in large numbers in from
ninety to one hundred days or more. He found also that many young salmon “summer

Evermann, B. W.: A preliminary report upon salmon investigations in Idaho in 1894. Bulletin U. S. Fish Com-
mission, vol. xv, 1895, p. 253, 1896; and A report upon salmon investigations in the headwaters of the Columbia River
in the State of Idaho in 1895, together with notes upon the fishes observed in that State in 1894 and 1895. Bulletin U. S*
Fish Commission, vol. xvi, 1896, p. 184.

b Rutter, Cloudsley: Natural history of the quinnat salmon. Bulletin U. S. Bureau of Fisheries, vol. xxn, 1902,,

132

BULLETIN OF THE BUREAU OF FISHERIES.

residents” remained in the headwaters of the Sacramento until the first winter rains,
when they all went out.

2. The salmon feed in the ocean for a period of years. For the chinook salmon
this period is believed to be from three to five years, though the evidence is not entirely
conclusive. The feeding period continues until maturity is reached.

3. At the end of the feeding and maturing period the salmon migrate up the Pacific
coast rivers to spawning grounds, which are sometimes only a few miles from the sea
and scarcely beyond brackish water, but often for hundreds of miles, apparently always
into cold fresh waters of the streams fed by springs, lakes, and mountain snow fields.

4. It has long been known in a general way that the migration of O. tschawytscha to
the spawning grounds is made wholly without food.

5. The most striking and least expected climax to this interesting life cycle was
discovered in 1894 by Evermann01 for the species O. tschawytscha and O. nerka, namely,
the fact that death invariably follows the spawning act. Evermann states, on page 260
of his preliminary report upon the 1904 expedition, that on September 13th he counted
72 dead salmon in a three-mile stretch of Salmon River and a mile or more of the lower
portion of Alturas Creek in Idaho. Only one live salmon was noted on this date. He
quotes numerous observations and conclusions of local men of the region tending to
confirm the deduction expressed on page 1 53 of his final report as follows: ‘‘The chinook
salmon which come to these waters die after spawning.”

This brief salmon history is repeated here for the reason that it is the most effective
way of presenting the setting for the problems that appeal to the physiologist. Of
these problems I have in a previous paper6 attacked the question of the acclimatization
of the chinook salmon to fresh water after its life in the sea. That study was based on
an examination of the blood and other body fluids. The special interest attaches to
the osmotic changes during the passage of the fish through the various degrees of brackish
water in the journey from the salt water of the sea to the fresh water of the rivers. The
further osmotic change during the run up the river was also studied.

The changes in the blood and body fluids are relatively slight and are carried on
very slowly and gradually. The osmotic changes in the body fluids give little or no
intimation of the length of time consumed by the fish in the transition from salt to fresh
water. Neither do the osmotic changes give any measure of the duration of the sojourn
in fresh water. In order to arrive at any adequate explanation of the profound changes
in the tissues and organs during the migration it becomes almost a necessity that the
rapidity of change in the environment and the total duration of the period be determined.
The time element in this change is indeed the most important factor, yet an almost
wholly unknown one.

The present paper gives the results of a preliminary experiment designed to secure
more tangible evidence as to the time element in the migration, especially on the Columbia

o Evermann, B. W., op. cit., vol. xvi, p. 151.

b Greene, C. W.: Physiological studies of the chinook salmon. Bulletin U. S. Bureau of Fisheries, vol. xxiv, 1904,
p. 429-

MIGRATION OF SALMON IN COLUMBIA RIVER. 133

River.® The question can be better understood when analyzed into the following points
or questions:

x. How long do salmon remain in brackish water? Or, stated more fully, how
rapidly do salmon pass from salt water through the various degrees of brackish water at
the mouths of the rivers?

2. What evidence is there that salmon swim back and forth with the ebb and flood
of the tide during the migration through brackish water?

3. When once quite within the fresh water of the rivers, how rapidly and how
continuously do salmon travel on their course up the rivers to the spawning grounds?

4. What evidences do salmon give of special responses to unusual conditions, such
as obstruction to their course, individual injury, etc. ?

PRINCIPLE AND METHOD OF EXPERIMENT.

This experiment is based on the principle that an understanding of the details of
the migration phenomena can only be had by a study of the movements of individual
fishes. The information derived from the movements of large schools of fishes, while
often of extreme value as corroborative evidence, can never be taken as conclusive
evidence of the movements of individuals. Even if it were safe to assume that the
movements of a given school of salmon represent the average of the movements of the
component individuals, yet it is quite impossible to identify certainly any given school
at different points along the river.

In order to subject the above questions to a preliminary test, I arranged a salmon
marking experiment on the lower Columbia River. The experiment was accessory to a
physiological investigation under my immediate direction during the summer of 1908.
Fifty-nine fish were marked with individual tags and liberated in the Columbia River
at the head of Sand Island, which is just within the mouth of the Columbia. The point
at which the fish were liberated was about eight miles up the river above the Canby
light-house on Cape Disappointment. This experiment was launched on August 14, 1908.

Superintendent Nicholay Hansen, of the Chinook (Wash.) fish hatching station,
contributed the catch of the Washington state fish trap. He also generously furnished
transportation to the trap and granted me the assistance of the hatchery foreman and
crew. I was assisted also by one of the staff of the United States Bureau of Fisheries.
On the above date the trap contained a two-days catch. We reached the trap at
about 9 o’clock in the morning, just before extreme low tide, and the net was lifted
soon afterwards. The fish were run from the net into a special live car used by the
Chinook hatchery crew to transport fish from the trap to the retaining grounds.
The fish were later dipped from the car with a large dip net, lifted out of the net
by hand, and quickly measured for total length. The marking tag was next inserted
and the fish turned loose into the current. It goes without saying that the utmost

a A briefer paper based on this experiment is published under the title, “An experimental determination of the speed of
migration of salmon in the Columbia River,’’ in the Brooks Memorial Volume of the Journal of Experimental Zoology, vol. 9,

1910.

134

BULLETIN OF THE BUREAU OF FISHERIES.

dispatch was used to prevent asphyxiation and care taken to avoid injury during the
necessary handling.

MARKING TAGS AND TOOLS.

The tags used to mark the salmon in this experiment were made of aluminum and
were extremely light and very strong. The entire tag or button weighed 2.6 grams

ounce). The tag was made of two pieces on the general principle of a Yankee
button (fig. 1). The piece B consisted of a circular disk, 1 mm. thick by 19 mm. in
diameter, which was forged to a hollow shaft, 7 mm. long by 7 mm. in diameter. The
shaft had a hole through its length some 4 mm. in diameter. A serial number was
stamped on the face of the disk (fig. 1, D). Piece A was a disk similar to B but forged
to a solid rivet, 4 mm. in diameter by 9 mm. long. On this face was stamped the words
“U. S. Fish,” as shown in E. When the rivet of piece A is inserted into the shaft of
B (fig. 1, C), the rivet projects 2 mm., which gives ample length for securing. When
the two pieces are adjusted and the rivet compressed, the soft aluminum fills the shaft
and the end is mashed down so that the two pieces can not be torn apart (fig. 1, D).

The marking pliers (fig. 2) used in this experiment were supplied by the manu-
facturer of the marking buttons. They were of cast iron, quite large, and rather heavy
for quick work. The pliers were 28 centimeters long and weighed 670 grams. Between
the handles there was inserted a hollow punch that cut a hole 7 mm. in diameter. The
width of the pliers was adjustable to the length of the button, the adjustment being made
by threading in one jaw. It was not necessary to use this adjusting device in the salmon
experiments, since the thickness of the salmon fin was never so great but that the pieces
of the button could be completely thrust home with the fingers without the aid of the
pliers.

CONDITIONS AND DETAILS OF MARKING PROCESS.

When a salmon is caught up in a dip net he struggles vigorously to get away. One
should use a relatively large dip net with a wide flat bottom (i. e., not the usual round or
kettle-shaped bottom). With such a net it is very easy to manage a fish through the
struggling stage so that it does no injury to itself. It is not necessary that scales should
be lost, even in such loose-scaled fish as the silver salmon.

In this experiment when a fish was caught it was held with the bottom of the net
just deep enough in the water for the fish to struggle against the resistance of the water.
While this method resulted in a goodly quantity of water being thrown over the operator,
it had the very desirable effect of quickly producing a temporary fatigue of the salmon.
As a result of this fatigue, the fish remained quiet for a number of seconds.

The instant a fish stopped struggling it was lifted out of the water, seized by the tail
with a strong grip of the hand, swung free of the net, and over the free arm of the oper-
ator. The next instant it was quickly but gently laid out on the measuring platform
and its length read off. The measuring platform consisted of a broad board with an
upright at one end. A meter stick was tacked to the board with its zero against the
upright. Loose folds of burlap were laid over the board and over the meter stick for

Bull. U. S. B. F. , 1909.

Plate XXVI.

Fig. 1. — The two pieces of the marking button are shown in A and B, the former especially
arranged to show the rivet, the latter to show the shaft. In C the two pieces are shown
put together but not riveted. In D the parts are riveted together, and in K the converse
side is figured.

Fig. 2. — Pliers used in attaching the marking buttons.

MIGRATION OF SALMON IN COLUMBIA RIVER.

135

the greater portion of its length. A fold of the burlap was so arranged that it could
be quickly thrown over the middle portion of the body of the salmon whenever desir
able, i. e., occasionally with the largest specimens.

When a fish was laid out on the measuring platform the tip of its nose was allowed
just to touch the vertical piece and its tail was extended to full length. The total length
was then read off by the measurer and announced to the recorder. The tail was, how-
ever, never released from the grasp of the operator during this move; a struggle is apt
to begin at any moment, and if the fish struggles it must be swung free into the air to
prevent pounding on the board and injury to itself. If the length was not caught by
the measurer before struggling occurred, the process, of course, had to be repeated.
Lifting a salmon from the water, taking it from the net, and reading its length on the
measuring board really consumed only a very few seconds — not so long a time as
required to describe the process.

After the length was read the next step was the insertion of the marking button.
This was done by the person who did the measuring. The buttons in this experiment
were all inserted in the caudal fin. The upper lobe was used except in a few cases where
a cleft was present, in which case the lower lobe was used for the button. The inserting
tool, previously described, although intended for use on the domestic animals, was reason-
ably workable on salmon. Its chief deficiency was in the fact that its use required two
very different movements. The first movement was to slip the handle over the lobe of
the fin in order to punch the hole for the button (see fig. 2). The second act was for
the purpose of compressing the button and riveting it securely in place. If the fish
began to struggle at the instant the button was being compressed, the button had to
be released instantly lest it be torn from the fin. In cases where the tail was released,
the unriveted button was usually thrown out and had to be reinserted. A special
tool is being devised for future work that will punch the hole, insert the button, and rivet
it home in one continuous movement. Such a tool will materially increase the rapidity
of the work.

The salmon that came through the marking process in good condition were imme-
diately released overboard in the direction of the open water. If there was any ques-
tionable degree of asphyxia, the fishes were released into the car and turned overboard
only when fully recovered. In two fishes that were markedly asphyxiated it was neces-
sary to use artificial respiration for a short time. Both v/ere strong and active when
ultimately released from the live car. The fishes took the water readily and quickly
swam away. My previous experience in handling live salmon enables me to state that
the present handling was well within the limits of treatment which salmon endure
without danger or risk.

The weight of the fishes was estimated by Foreman Borkman, who has a reputation
for skill in the accuracy of his judgments. Mr. Borkman’s estimates have come very
close to the actual weights of certain of the fish retaken. In at least one of the largest
fish the actual weight tallied exactly. The judgments of the weight were arrived at dur-
ing the handling of the fish in the net and on the measuring board. These estimates

136

BULLETIN OF THE BUREAU OF FISHERIES.

are only of relative value, however, as indeed are the measurements of length in this
preliminary test, and no calculations are to be based on either set of measurements.

DISCUSSION OF TECHNIQUE.

It should be remembered that the procedure related here was done on the first
and only attempt to tag fish in the migration run up the Columbia River. The details
are given rather fully for the guidance of those who may in the future try this or similar
experiments. The technique in handling can be improved as regards two factors; first
in the convenience of arrangements for increasing the speed of dipping, measuring,
and tagging the fish; second, in the skill which comes with continued handling which will
reduce the chances of local injury and of asphyxiation of the fish.

The fishes suffer no physical injury up to the point where the hole is punched in the
tail to receive the button. Careless or inexperienced handling, however, may lead to
some injury. For example, if the meshes of the dip net are too large it requires care
lest the fins be split or a gill torn in removing the fish from it. These injuries can be
reduced by care and skill, as has just been stated. Silver salmon will also lose scales
in struggling unless they are swung free of the operator’s body. For example, if a sil-
ver salmon should begin to struggle just as it is swung into the arms of the operator
and the operator should undertake to hold it firmly, a number of scales would almost
invariably be lost. But if the fish be quickly swung by the tail free of the operator’s
body until the struggles cease no injury will be done.

Other fins, such as the dorsal or pectorals, might better have been tagged than the
tail fin. The objection can be legitimately raised that, since the tail is the most active
organ, it would be better to run no risk of its injury, even though the injury were slight,
as in this experiment. On the whole, I am of the opinion that this is a well-founded objec-
tion. If the button is inserted a little too near the base of the tail, there will be some
delay in the healing of the wound. Most of my fish were reported as retaken in fine
condition, but some that were taken at The Dalles, Oreg., and had therefore made the
longest runs, were reported to have buttons that had become very loose.® The holes
for the insertion of the buttons had not healed — in fact, had grown larger. The dorsal
fin, or even the adipose fin, are possible points that might prove more advantageous for
the insertion of the marker. The possibility of tearing out the button in gill nets and
the like must always be given consideration in making a choice of points for marking.

As for the tag or marker itself, various criticisms have or may be offered regarding
it — that it is too large, that it is too heavy, that it may frighten the fish, since it is bright
and shining, that “it may act to the fish like the proverbial tin can to a dog’s tail.”
All of these have little basis in fact and reason. Considered in relation to the size and

a ‘'[On August the 25] a 35-pound chinook salmon, in the very best of condition, button snugly in place without any
sign of sore, was caught by seine about 15 miles upstream (from the state trap) in the Columbia River, in the main ship
channel opposite Altoona, Wash.” — Wm. H. Bailey, of the Miller’s Sands Fishing Company, of Altoona, Wash.

“We got a steelhead to-day. No. 98. * * * This button wears a big hole in the tail, large enough almost to

drop out.” — Frank A. Seufert, The Dalles, Oreg., under date of October 5, 1908.

“I inclose herewith serial tag No. 87, taken from a io-pound silver salmon on the 10th of October, caught by
Mr. Ed. Le Roy in a trap at the head of Cottonwood Island. Mr. Le Roy states that the fish was in first-class condition
when taken.” — H. C. McAllister, master fish warden of Oregon.

MIGRATION OF SALMON IN COLUMBIA RIVFR.

T37

weight of the fish, I regard this particular aluminum button as almost ideally light
and strong and conspicuous for use in tagging salmon in fresh water. It is probably
not visible to the fish that wears it, so can not frighten him, and the possible effects on
other individuals are of little importance. As for the “tin can” comparison, this point
makes a very good joke, but has no basis in fact. I have marked numerous salmon on
the spawning grounds and find that the marked fish come and go with the unmarked
fish without any disturbing behavior to distinguish them from the other fish of the
schools.

For sea-run fish, where the sojourn in salt water lasts for a year or more, aluminum
will not do. Salt water corrodes aluminum and the disk will probably drop off within
a year. The corroding property of aluminum in salt water is, however, very valuable
as an accessory check on salmon that are making the journey through tide water. (See
figs. 3 and 4.) The degree of corrosion of the aluminum button indicates the relative
immersion in salt water, although from this fact alone one can not distinguish between
the corrosion due to a relatively short immersion in concentrated and that produced by
a longer immersion in more dilute sea water.

LITTLE INJURY TO FISH IN HANDLING.

The necessary physical injury to salmon while marking them by the methods used
in this test are two, or at most three. The first of these is the degree of asphyxiation
produced by the handling of fish out of water. The second injury is that of cutting the
7 mm. hole through the caudal fin. The third is the physical effects of the handling.

By asphyxiation is meant the condition which results from the inability of the
salmon to secure the usual quantity of oxygen and to get rid of the carbon dioxide
rapidly enough. With fishes this exchange of oxygen and carbon dioxide takes place
between the blood in the gills and the water flowing through the mouth and over the
gills, the oxygen being absorbed from the water into the gills and the carbon dioxide
exchanged at the same time passing in the opposite direction. If a fish is taken from
the water and air is allowed to pass freely over the gills, the conditions for the gaseous
interchange between the air and the blood through the gills is for a time as good, or
even better, than with water. The trouble comes when the gill covers are tightly closed
down and when the gill filaments, no longer supported by water, adhere together in a
mass. These conditions sharply reduce the respiratory efficiency, and asphyxiation
results. This is slight at first, but is more intense and more rapidly developed later.
One who gives attention to the fact can not but be impressed by the degree with which
salmon withstand asphyxiation and the ease with which asphyxiation can be overcome
b)r artificial respiration. In the above experiments only two salmon required the arti-
ficial respiration. One of these was a fish weakened by old injuries that were quite
severe. I do not consider ordinary mild asphyxiation of any particular injury to the
fish unless it be so pronounced that the irritability of the respiratory center in the
medulla is lowered enough to stop completely all respiratory movements.

The injury to the fish from cutting the small hole in the tail for the button is very
trifling indeed. This cut is for the fish about like making a pin prick in the skin of the

138

BULLETIN OF THE BUREAU OF FISHERIES.

hand to a man. It gives a stimulation that produces physiological reflexes for the
moment, and that is small. If the button is carelessly inserted, it might tend to further
stimulate the skin during the succeeding two or three hours, but the effects even in this
instance would be so slight that it seems to me there would be no very noticeable influ-
ence on the fish. Scarcely a fish is caught in the upriver fish wheels where I have
worked but that shows physical injuries greater than this.

There still remains the general effect of the handling. No doubt a certain amount
of fright and stampeding must have resulted from the handling of these fish, just as it
would have resulted if the same fish had been turned loose directly by the lifting of the
trap or from a seine. This effect will be discussed more fully in the next chapter.

EFFECTS OF MARKING ON MIGRATION.

The question that naturally presents itself is, What effect will all this have on the
migration and on the manifestations of the migratory instinct of the salmon? In my
opinion, it will have little or none, and the following pages will reveal my reasons.

First of all, one must divest himself of the customary attitude toward reactions
of such complex animals as man and the domestic animals. These are far too complex
for comparison with salmon. The reactions of a form so low as the salmon must be
considered in the light of its biological development.® For example, the salmon brain
is very simple in its type and low in its development. The cerebral lobes are relatively
small and the so-called cortex layer consists of little more than a single and simple layer
of nerve cells. That it possesses anything beyond the very simplest of association
fibers is improbable. With such a low form of brain the salmon can not carry out very
complex reactions; it has no machinery for such reactions.

The simplicity of the salmon’s brain when compared with that of a bird or of a
mammal is like the mechanical simplicity of the spiral screw in the ordinary cannery
soldering device when compared to the most complicated intricacies of the vacuum
solderless heading machines. This salmon brain is complicated enough to coordinate
certain particular functions; for example, the circulation, respiration, muscular motions,
etc. That the salmon may carry out consecutive nerve reactions such as psychic
deductions is impossible. To illustrate, when the hole is punched in the tail in the tag-
ging process, there are slight muscular movements in the region of the tail — local motor
reflexes. Sometimes, but by no means always, there may be general motor reactions and
the fish struggles to free itself. There are also momentary inhibitions of respiration
involving one or two respiratory movements, and, judging by other experiments conducted
to determine the fact, there are reactions on the circulatory apparatus. All these are
of the simpler reflexes and are comparatively slight, and disappear within a few minutes
at most. The mechanical stimulus of inserting the marking button furnishes an occasion
for the repetition of the whole series of the above reactions, but in a milder degree. If
one can rely on the observations made on sharks, which are not far removed from the
salmon in their development, one must conclude that mutilations much more severe

° F.dingcr.L. : Ueber das Horen der Fische und anderer niederer Vertebraten. Zentralblatt fiir Physiologie, bd. xxii,
1908, p. 1.

MIGRATION OF SALMON IN COLUMBIA RIVER. 1 39

will be ignored by the fish within a very short time — a time probably measured by
minutes.

The chief objection one can raise here is to assume that the button when once
inserted acts as a continuous source of stimulation to the individual fish, thus driving
it into panic. One may assume that the button is not where the fish can see it
and that it makes no sound which the salmon can hear, granting the questionable fact
that the fish recognizes unusual sounds. The only other possibility is that the button
is a continuous source of cutaneous sensory stimulation. This last seems plausible,
but the fact is that either the wound will heal and adapt the surface to contact with
the button or the injured surface will begin to degenerate, in which process the local
nerve endings will soon lose their function and become insensitive.

Those conditions which lead to the migration of the salmon are the chief directive
stimuli for the salmon at this phase of its existence. They overshadow all others. In
comparison with this series of reactions, the so-called migratory instinct, small physical
injuries are as nothing. If it were not so, the numerous fish that are injured by seals
or sea lions, that are torn by hooks and the rocks, that are even more profoundly injured
in the escape from the gill nets, would not appear in such vast numbers on the upper
fishing grounds of the river. By my own count on different occasions net-injured fish in
the catch of some of the wheels during the summer of 1908 amounted to from 25 to 60
per cent of the total, and I am reliably informed that at certain times the per cent may
run to 80 or 90. My observations indicate that some of the salmon recover from these
bruises received from the gill nets, though what per cent of recovery occurs I can not
say. Salmon are, however, frequently taken on the Celilo fishing grounds with injuries
so profound that one wonders how they could have survived so long, yet these severely
injured fish are forging ahead toward the spawning grounds. The migratory stimuli
overshadow even these most profound injuries and continue to do so until death ends
the struggle, and death must inevitably end the struggle of these unfortunates long
before the spawning act is consummated.

DETAILED RESULTS OF EXPERIMENT.

The location chosen for the marking of the salmon of this experiment is the Wash-
ington state fish trap, a few hundred yards above the head of Sand Island. The point
is some 7 or 8 miles within the mouth of the Columbia, on the Washington side, and
10 or 12 miles below Astoria. The border of the channel above the island is bounded
by a line which represents the legal limits regulating the setting of fish traps by the
fishermen. The state trap is located just outside these limits, permission having been
secured for the location by the Washington fisheries authorities from the United States
engineers in order to catch fish for the Chinook hatchery. The point also marks the
limits on the north to the area over which gill-net fishermen drift their nets. In fact,
gill netters occasionally have their nets caught by the cross currents and thrown on
this trap. Standing, as it does, just on the border of the north channel on the line that
separates the gill netters’ field on the one hand from the set traps on the other, this
trap is especially well located for this experiment. It is in the area of brackish water,

140

BULLETIN OF THE BUREAU OF FISHERIES.

yet it is several miles upriver from the lower fishing limits, and therefore gives a chance
to test whether the marked fish ever run toward salt water.

Of the 59 fish marked and liberated on August 14, there were 25 chinook salmon
(1 Oncorhyiichus tschawytscha) , 16 silver salmon ( O . kisutch), and 18 steelheads ( Salmo
gairdneri). These fish ranged in total length from 41 to 103 cm. for the chinooks,
47 to 78 cm. for the silvers, and 71 to 90 cm. for the steelheads. The largest chinook
weighed 35 pounds. The fish, while few in number, were well distributed as regards size,
Information as to the import of the experiment was given out to the fishery interests
on the Columbia. Fishermen were requested to record the place and details of the
catch of any marked fish, to note any injuries or other facts of interest, and to report
the same to me. Fishermen were also requested to send in the marking buttons with
the tails of the fish. The various salmon-packing firms were especially helpful in
reporting catches and in forwarding the marking buttons.®

Seventeen out of the 59 fish marked were retaken and reported to me. This
number retaken represents 29 per cent of the fish liberated, a very favorable propor-
tion considering the 12 to 15 days of closed season following the 25th of August. Of
these fish 6 were chinooks, 6 were silver salmon, and 5 were steelheads. The time of
the retaking extended from the date of the marking, August 14, to October 10, a total
of 57 days. The general record of all the fish retaken is presented in table 1.

Table I. — Distribution, Time, and other Facts Concerning the 17 Salmon and Steelheads
Retaken out of the 59 Marked and Liberated at the Washington State Trap, Columbia
River, August 14, 1908.

Species, number,
and sex.

Weight.

Length.

Date

retaken.

Days

out.

Place taken.

CHINOOK.

8ocT

Pounds.

Cm.

103

Aug.

1 1

Ship channel opposite Altoona.

I09< ?

Aug.

Chinook, Wash.

HOC?

Aug.

Do.

113$

Aug.

Republic spit.

Ii5c?

i-5

Aug.

Chinook, Wash.

I23C?

Sept.

Opposite Brookfield.

SILVER.

75c?

9- 5

Sept.

Celilo rapids.

76c?

14- 5

Sept.

Do.

79c?

Sept.

Do.

87?

Oct.

Cottonwood Island.

89c?

Sept.

1 3

Celilo rapids.

97?

Sept.

Do.

STEELHEAD.

Oct.

Celilo rapids.

1 16

Aug.

Republic spit.

124

1 1

Sept.

Celilo rapids.

125

1 Bet. Sept.
1 14 and 20

} 31-36

Cottonwood Island.

Aug.

2 1

Chinook, Wash.

a Marked fish were caught by or reported to me by the following persons and firms: P. S. McGowan & Sons, McGowan,
Wash.; N. Futrup, Chinook, Wash.; W. and M. Mclrvin, Chinook, Wash.; Wm. Graham, Ilwaco, Wash. ; Pillar Rock
Packing Company, Pillar Rock, Wash.; Wm. B. Bailey, of the Millers Sands Fishing Company, Altoona, Wash.; “Sun-
derland Trap,” Brookfield, Wash.; Ed Le Roy, Cottonwood’ Island; Seufert Brothers, The Dalles, Oreg. ; B. Soderlund,
Chinook, Wash.

MIGRATION OF SALMON IN COLUMBIA RIVER.

141

Table I. — Distribution, Time, and other Facts Concerning the 17 Salmon and Steelheads
Retaken Out of the 59 Marked and Liberated at the Washington State Trap, Columbia
River, August 14, 1908 — Continued.

Species, number,
and sex.

Distance

from

state trap.

How taken.

By whom taken or reported.

CHINOOK.

8ocf

Miles.

Millers Sands Fishing Co., reported by Wm. B. Bailey.
W. N. Futrup.

I09cf

Trap

a 4

Sunderland’s trap, reported by H. C McAllister.

SILVER.

75c?

Do.

87?

89/

Seufert Brothers Company.

210

Do.

STEELHEAD.

Seufert Brothers Company.

Pillar Rock Packing Company.

Seufert Brothers Company.

?.:

Trap

B. Soderlund.

a Downstream.

The fact that aluminum is corroded by immersion in salt water has in a degree
served to indicate the career of the marked fish after they were turned back into the
Columbia. The degree of corrosion does not enable one to distinguish as between a
relatively short time in concentrated salt water and a longer time in relatively dilute
brackish water, but where corrosion occurs extensively in a short period of time, as in
fish number 80, which was out only 11 days, it is pretty safe to assume that the fish
spent most of the time in relatively concentrated sea water. Tables and figures are
presented below for the purpose of showing the degree of corrosion of the marking
buttons. An examination of these tables and figures will show that each group of
fishes of the three species liberated had certain individuals that had gone into sea water
long enough to produce corrosion of the marking buttons.

Table II. — Marked Chinook Salmon Retaken, Showing the Extent of Corrosion of the
Marking Buttons by Sojourn in Salt Water.

Number.

Time out
in days.

Distance

from

state

trap.

Corrosion of marking button.

“U. S. Fish” surface.

Numbered surface.

Miles.

80^

1 1

Very light corrosion in groove around

Corrosion over four-fifths of raised rim of

head of rivet.

shaft and around rivet.

T r«n ,-f

Smooth.

t t n T1

Do.

a 4

Do.

123c?

Blackened and slight corrosion around

Deeply etched about rivet where it emerges

head of rivet.

from shaft, and on inner margin of

shaft.

a Downstream.

142

BULLETIN of the bureau of fisheries.

CAREERS OF INDIVIDUAL SALMON RETAKEN.

CHINOOK SALMON.

Of the ehinook salmon, three, numbers 109, no, and 115, were retaken in traps in
the immediate vicinity of the point where they were liberated. They were taken at the
next lift of those traps on August 15 and may have entered the traps at any time during
the interval of a little less than 24 hours following their liberation. These three salmon
are the only fish of the marked series reported retaken by the traps of the vicinity.
They are of interest chiefly as showing that the great majority of the fish took to the
main channel in the direction in which they were liberated. The currents at the time
of liberation were toward the trap field. On the theory that salmon stem the currents in
the tide waters as well as in fresh water, it is obvious that the liberated fish would be
directed away from the trap field. These observations are in the main in harmony with
this theory.

Chinook number 1 13 was caught 6 days after liberation and by a purse seine operating
near Republic spit. Republic spit is a point marked by the wreckage of a vessel which
obstructs the channel off the south shore of Sand Island. It is located about 4 miles
down the river from the state trap. The aluminum marking button of this salmon is
quite smooth. Had the fish gone out into the pure sea water it might have shown some
slight signs of corrosion. Six days in brackish water would scarcely lead to corrosion
of the aluminum. It is probable, therefore, that this salmon had spent the time swim-
ming back and forth in the tide water of the vicinity in the process of acclimatization.
Whether or not it swam long distances, either upriver or out to sea, does not appear, but
judging by the results of the comparison with specimen number 80 it is probable that
the time of number 113 was spent in the relatively fresh water in the neighborhood of
Sand Island.

Number 80 was taken 15 miles up the river from the state trap and on the eleventh
day after liberation. The time required by a straightaway swim for the salmon to
travel 15 miles could not be over one or two days (three of the silvers averaged over 7
miles a day, see numbers 75, 76, and 89) ; hence this fish had about 9 days in which its
movements are not accounted for. The corrosion of its tag is slight on one side but
quite extensive on the other. So much corrosion in the short time of 1 1 days can onty
be accounted for on the theory that the fish was in relatively salt water. My guess would
be that this fish went well out toward the jetty or even beyond during its 11 days’ stay,
and that the average of its time was spent in water as salt as in the vicinity of lower
Sand Island or of Canby light.

Chinook number 1 23 was out 3 1 days, yet this salmon had traveled upriver only 1 5 miles
when taken near Brookfield. Its button was the second deepest etched of the series
recaptured. The corrosion indicates a sojourn in salt water or in relatively concentrated
brackish water. The evidence given by the corrosion of this button is to my mind
conclusive evidence that its bearer had spent considerable time well below the point
where it was liberated, probably at or beyond the lower end of Sand Island. I would

Bull. U. S. B. F. , 1909.

Plate XXVII.

Fig. 3. — Photograph of eleven of the marking buttons after they were recovered from the marked
fishes. This and the next figure show the corrosion of aluminum 011 the exposed surfaces.
The buttons are shown natural size.

Fig. 4. — Photograph of the converse facesof the eleven marking buttons shown in figure 3.
The buttons have the same relative positions in the two photographs. Reading
from left to right the numbers of the top row are 75, 76, and 79; of the middle row 80, 87,
89. and 98: and of the bottom row 97, 123, 124, and 125. Buttons photographed natural,
size.

■

MIGRATION OF SALMON IN COLUMBIA RIVER. 1 43

value this evidence second only to actually capturing the salmon out toward the sea
from the state trap.

Marked Chinooks were not recaptured above Millers Sands. Whether they got
through during the closed season from August 25 to September 12, or from what other
reason they were not retaken, is wholly a matter of conjecture. Sharp lookout was
kept for them all along the river at the United States hatcheries, and especially at the
Ontario (Oreg.) state hatchery, where I collected in early September. No marked fish
appeared at the Ontario station up to the close of the fishing about November 1, and
none were taken at the government stations.

SILVER SALMON.

The silver salmon, with a single exception, were all retaken by Seufert Brothers
Company on the Celilo rapids at the Tumwater seining grounds. One, number 87,
was taken at- Cottonwood Island, by Mr. Ed Le Roy. This last fish was out the longest
of all the fish retaken — 57 days.

An examination of table III and of figures 3 and 4 will show that great diversity
exists as to the degree of etching by corrosion shown by the buttons of these silver salmon.
The button of number 79 was smooth and clean on both sides. This salmon was out 33
days, but evidently did not spend much if any of its time in brackish water after it was
marked.

Table III. — Marked Silver Salmon Retaken and Extent of Corrosion of Marking Buttons

by Sojourn in Salt Water.

Number.

Time out
in days.

Distance
from state
trap.

Corrosion of marking buttons.

“ U. S. Fish” surface.

Numbered surface.

Miles .

210

Slightly corroded about head of rivet . . .

Deeply corroded on head of shaft and about

rivet.

about rivet, but not deeply pitted.

210

Slightly corroded about one-half the

Corroded over entire head of shaft, and

head of rivet.

deeply pitted about rivet and on inside

of end of shaft.

210

Deeply coiToded and pitted over this

Corroded on one-third the head of shaft and

surface of the button except head of

slightly on end of rivet.

rivet; most corroded of all the but-

tons.

Number 97, which was out the same length of time and retaken at the same place
as 79, had the most deeply corroded and pitted button of the entire series. It was even
more corroded than chinook button number 123 which was out 31 days and was retaken
only 15 miles up the river. Number 89 was also a deeply corroded button. These two
fish, 89 and 97, bear evidence of a considerable sojourn in salt or strongly brackish water
after they were tagged. The buttons of the 3 remaining silvers grade between the
extremes just discussed, number 75 being almost smooth and 79 considerably corroded.

144

bulletin of the bureau of fisheries.

Yet it will be noted that these 5 fish were retaken by Seufert Brothers within the period
of 5 days from September 12 to 16. Silver salmon number 87 is a decided exception
in this list. It was retaken only 70 miles up the river and was out the longest time of all
the marked fish, namely, 57 days. Its button, however, does not present a history of
long contact with salt water. It is etched to some degree on one surface, but not more
than would be possible by a long career in slightly brackish water.

steelheads.

Of the 18 steelheads marked, only 5 were retaken. One of these, number 116, was
caught down the river 4 miles below where it was liberated and between four and five
hours after liberation. As already stated, the fishes were liberated on a strong flood
tide and it is evident that this particular fish at once made about a mile an hour speed
toward sea. It was taken by purse seine in the channel near Republic spit in the same
locality where ehinook number 123 was captured 6 days later. These two fishes give
absolute proof of downstream movements of salmon. The fishing annals of the lower
Columbia have many instances of similar outward movements of schools of salmon.

Tabu® IV. — Extent or Corrosion or the Aluminum Marking Buttons oe the Steelheads

Retaken.

Number.

Time out

Distance
from state
trap.

Corrosion of marking surface.

in days.

“U. S. Fish” surface.

Numbered surface.

Miles.

210

Slightly corroded about head of rivet . . .

Markedly corroded over head of shaft and

a 4

around rivet within the shaft.

30-35

Slightly corroded about rivet.

Deeply corroded about rivet and slightly
pitted.

Button not preserved.

125

Corroded about head of rivet

Button not preserved

a Downstream.

It is said that at certain times, following a period of stormy weather or when for
other reasons the gill nets have not been operating on the lower river, the seines on
lower Sand Island capture fish with definite marks received from fishing gear — marks
that can be accounted for only on the theory that the fishes have moved seaward after
receiving the marks.

One steelhead was reported captured in a trap only about one-half mile upriver
from the state trap where it was liberated. This fish was out 7 days, but as its button
number was not taken and since the button itself was not sent to me, no record could
be made of the character and extent of its corrosion.

Of the two steelheads retaken by Seufert Brothers, number 124, out 33 days, shows
slight corrosion, but number 98, out 52 days, shows marked corrosion. Evidently the
former spent little time in tide water, while the corrosion of the button of the latter
indicates considerable contact with salt water.

MIGRATION OP SALMON IN COLUMBIA RIVER. ^145

The steelhead number 125, which was caught only 70 miles up, shows a salt-water
history similar to that of number 98, which had gone 210 miles up the river.

MIGRATION SPEED.

The speed of the total migration is unquestionably divided into two periods, first,
the migration through the various stages of tide water, and, second, the migration up
the river when once quite within fresh water. This preliminary experiment was launched
in the tide-water zone, hence can not directly solve either speed period. In discussing
the three groups of fishes a number of instances have been given to show that these
fishes spent much time in brackish water after their marking. One may assume the broad
working hypothesis that salmon travel at an average speed that is apparently uniform
for different individuals under similar conditions. Table v shows the days out, total
distance traveled, and the average speed made for the time. A glance at the table
suffices to show either that the hypothesis is unsatisfactory or that a number of the
salmon have not made direct runs upstream.

Table V. — Marked Fish Arranged in the Order of the Average Time Taken to Travel the

Distance Covered Before Recapture.

Species.

Silver. . . .
Do. .
Do. .
Do. .
Do. .
Steelhead.
Do. .
Do. .
Chinook. .
Silver. . . .
Chinook. .

Do. .
Steelhead,

Tag

number.

Days out.

Distance

traveled.

Average
speed
per day.

M iles.
210

Miles.

7- 50

210

7. 24

210

7. 00

210

6.36

210

6. 36

124

210

6. 36

210

3 - 85

125

±35

±2.00

1 1

1. 36

1. 23

123

.48

11 3

a 4

. 66

1 1 6

a 4

24. 00

a Downstream.

Rutter® branded a number of salmon on the Sacramento River in September, 1900,
at Rio Vista, which is above the salt-water tides of the river. Three of these fish were
retaken, two at the Mill Creek hatchery and one at Battle Creek. They covered the
distance in an average speed of 4 to 5 miles per day. This speed was exceeded by six
of the marked fish in the present experiment, these six making an average individual
speed of from 6.36 to 7.50 miles a day with a general average of 6.8 miles.

The observations of the commercial fishermen on the Columbia River make it
quite probable that the highest speed shown in table v is low for the migration rate of
Columbia River salmon under favorable conditions of the river.6 The statistics of the

a Rutter, Cloudsley, op. eit., p. 124.

Mr. Frank A. Seufert writes me as follows: “Usually it is from 7 to 9 days from the time a run is reported entering
the river in July or August when we get the effects of it here.” Seufert Brothers’ fishery is 210 miles up the river, which
would give a speed of 23 to 30 miles a day for a heavy run.

48299° — Bull. 29 — 11 10

146

BULLETIN OF THE BUREAU OF FISHERIES.

commercial fisheries would indicate a maximal speed of three or four times that given by
my highest rates. It is very probable, therefore, that the lack of uniformity in speed
shown in the table is due to days consumed in ways not accounted for by the direct run
through fresh water in the course up the river.

An interesting side light is thrown on these observations if the speed for all is
computed on the basis of the average speed made by number 76, the highest on the list.0
Table vi presents the results of this recomputation.

Table VI. — Results of Computing Time Actually Taken in Run, on Basis of Average

Speed of 7.5 Miles a Day.

Species and number.

Distance
traveled
in miles
from
point of
liberation.

Days out.

Days required
to cover
distance at
an average
speed of 7.5
miles a day.

Days un-
accounted
for.

Silver, 75

210

Silver, 89

210

Silver, 79

210

Silver, 97

210

Steelhead, 124

210

Chinook, 80

1 1

Steelhead, 98

210

Steelhead, 125

Chinook, 123

±31

Silver, 87

Chinook, 113

0 4

t> 6

o Downstream. b Had not yet left tide water.

I fully recognize that table vi is based on an assumption. Nevertheless, it can
not at present be displaced by observed facts, and serves better than an.y other method
devised to illustrate the great discrepancy in the time consumed by numbers 80, 87, 98,
123, and 125. The last column of the table shows that these particular fishes must have
played around in the lower waters of the Columbia. Certain of them have not gone
beyond tide water — for example, 80 and 123. This last fish has taken a whole month
to go only 15 miles up the river. By the computation there are three others that have
about the same time available for playing around or resting quietly somewhere, and the
history of number 123 renders it quite probable that they all spent this extra time in
tide water.

We have, therefore, from this experiment two series of facts that throw light on
the life history of salmon in tide water, namely, the etching or corrosion of the aluminum
marking buttons and the probable time consumed by the salmon after they were marked
at the state trap before they began the strictly fresh-water journey. Both observations
show an unexpectedly long time in tide water, i. e., as long as 30 days (chinook number
80) or even 48 days (silver number 87).

Rutter 6 has advanced the theory that salmon make the journey through tide water
by running up during the ebb and down during the flood tide, stemming the current each

a It is evident from the slight corrosion of the button of this fish that it spent some time in brackish or salt water.
It made, therefore, a really higher average speed during the time in fresh water.
b Rutter, Cloudsley, op. cit., p. 122.

MIGRATION OF SALMON IN COLUMBIA RIVER.

147

way. He applied this principle in his studies of the ehinook salmon of the Sacramento
River. Following the variations in the catch of the fisheries at the different towns
along the bay and lower Sacramento, he estimated that a school of salmon made its
way from Vallejo, on the lower bay, to Sacramento, on the river, in 4 days for the spring
run when the river is relatively high. In the summer and fall they move more slowly.
This he explains bv the fact that the river is low and the tides in the bay therefore more
nearly equal in time, thus requiring more time for the salmon to pass through the bay.

My fish were marked in August, hence are to be compared with the movements of
fall fish as described by Rutter. I accept Rutter’s hypothesis as partially explaining the
movements of salmon in tide water. Undoubtedly currents in the rivers are directive
on the movements of the migratory fishes. In tidal waters this factor is still active.
In the tidal area at the mouth of a river the relative time of the flood and ebb currents
rapidly changes toward the upper tidal limits, where the former entirely disappears. If
salmon were directed by currents alone they would make the journey more and more
continuously as they come within the brackish area. Figured on the basis of the dif-
ference of the duration of the flow of the flood and ebb currents as against the observed
speed of salmon, it is obvious that the fish would pass through the tidal area in a much
shorter time than these observations indicate. Other factors are operative, for currents
alone are not sufficient to account for the movements. I believe that a much more
influential factor is the condition of the water as regards its amount of salt. Salmon
are sharply responsive to the stimulus that comes from variation in the degree of admix-
ture of sea water and river water in the tidal area, a stimulus that is doubtless in the
nature of a negative chemotaxis. Attention has already been called to the changes in
the osmotic equivalents of the blood in fresh-water salmon as compared with those in sea
water. These changes, though slight, are due in large measure to the transition from a
sea-water environment to one of fresh water. Such physiological adaptations require
a relatively long time. If a salmon entering the mouth of the Columbia should swim
into an area of water relatively fresh before his gills and other epithelial tissues were
sufficiently adapted to it, chemotactic reaction would stimulate him to increased activity,
which, by the law of such reactions, would lead him in the end toward salt water. These
journeys into areas now relatively fresh, now relatively salt, but in the balance ever
toward fresh water, will continue until the epithelial tissues of the individual fish have
become adapted to life in fresh water. The rate at which this adaptive process takes
place determines the total time required for the passage through the tidal area. The
observations recorded in this experiment indicate a very much longer time spent in
tide water by the salmon on the Columbia River than allowed by Rutter for salmon
on the Sacramento. While not numerous enough and not sufficiently varied to make
the deductions absolutely conclusive, yet these experiments strongly indicate that
salmon spend not less than from 30 to 40 days in passing the tidal area of the lower
Columbia.

148

bulletin of the bureau of FISHERIES.

SUMMARY OF CONCLUSIONS.

Remembering that this experiment is preliminary and that the observations are
entirely too few to make the deductions conclusive beyond question, still the following
tentative answers may be given to the questions announced in the beginning of this
paper.

1. Salmon may take from 30 to 40 days to pass through the brackish water within
the limits of the fishing waters at the mouth of the Columbia River.

2. That salmon spend considerable time swimming back and forth in tide water
during the acclimatization to fresh water is indicated (a) by the fact that two fishes
were taken below the point at which they were marked, ( b ) by the corrosion of the
aluminum marking buttons by salt water, and (c) by the long time spent by certain
fishes in reaching the lower limits of fresh water.

3. When wholly within fresh water, the silver salmon and the steelhead make the
migratory journey at an average speed of from 6 to 7^2 miles a day and probably more.

4. There is little evidence that the process of marking or that the partial obstruction
of the course by fishing gear does more than produce a temporary checking of the
migratory journey.

NATURAL HISTORY OF THE AMERICAN LOBSTER

By Francis Hobart Herrick, Ph. D., Sc. D.

Professor of Biology, Western Reserve University, Cleveland, Ohio

149

CONTENTS.

Page.

Introduction 153

Chapter I. The lobsters and allied Crustacea; their zoological relations, habits, development,

and use as food 155

Natural history of the Crustacea 155

Development of the Crustacea 162

Family life in crayfish 167

II. The American lobster; its economic importance and general habits 169

Geographical range 170

History and importance of the lobster fisheries in brief 170

Capture, transportation, and acclimatization of the lobster 173

Habits and instincts of the adult lobster 177

Migratory instincts 180

Movements of tagged lobsters 180

Movements off Cape Cod and at Woods Hole 18 1

Optimum temperature 182

r Influence of light and nocturnal habits 183

Burrowing habits 184

Food and preying habits 185

Cannibalism 188

Review of the instincts and intelligence of the adult lobster 188

Color in the adult 191

III. Giant lobsters 194

Greatest size attained by the lobster 194

IV. Molting 200

The skin and shell 200

Periods, conditions, and significance of molting 201

The molting act 204

Withdrawal of the big claws 206

Molting of the “hammer claw” in the snapping shrimp Alpheus 207

Changes in the skeleton preparatory to molting 207

The gastroliths or stomach-stones 208

Hardening of the new shell 21 1

Relation of weight to length in adult 212

Proportion of waste to edible parts in the lobster 214

V. Enemies of the lobster 215

Predaceous enemies 215

Parasites and messmates 213

Diseases and fatalities of the lobster 217

VI. Anatomy of the lobster, with embryological and physiological notes 219

Body 219

Internal skeleton and head 220

Appendages 222

Mouth parts 227

The slender legs 229

Central nervous system 230

Peripheral stomato-gastric system 231

Sense organs 232

NATURAL, HISTORY OF AMERICAN LOBSTER. 151

Page.

Chapter VI. Anatomy of the lobster, with embryological and physiological notes — Continued.

Sense organs 232

Eyes 232

Sensory hairs 234

Relation of setae to hatching and to molting 235

Touch, taste, and smell 236

Balancing organs or statocysts 238

Muscles 241

Blood and organs of circulation 242

Heart 243

Pericardial sinus 243

Arteries 244

Arterial supply of the swimmerets 245

Gills 246

Branchial cavity and respiration 247

Course of the blood in the gill 248

Alimentary tract 249

Grinding stomach 249

Liver 251

Kidneys or green glands 252

VII. The great forceps, or big claws 253

The crustacean claw 253

The great chelipeds 254

Lock hinges of big claws 255

Asymmetry in the big claws of the lobster 256

Torsion of the limb 257

Breaking plane and interlock 259

The toothed claw or lock forceps, and its periodic teeth 260

The cracker, or crushing claw 264

Development of the great forceps 266

Variation in position of the great forceps 274

Symmetry in the big claws 275

Changes in the toothed claw at molting 278

VIII. Defensive mutilation and regeneration 281

Autotomy or reflex amputation 281

Restoration of lost parts 283

Monstrosities 285

IX. Reproduction 288

Sexual distinctions 288

The ripe ovary 289

Development of the ovary to the first sexual period 290

Cyclical changes in the ovary after the first sexual period 291

Disturbances in cyclical changes in the ovary 292

Period of adult life or sexual maturity 293

Limits of the breeding season 294

Frequency of spawning 295

Number of eggs produced 298

Breeding habits and behavior in crayfish .0o

Pairing habits in the lobster 302

Preparation for egg laying : Cleaning brushes of the lobster 303

Egg laying 3o5

152 BULLETIN of the bureau of FISHERIES.

Chapter IX. Reproduction — Continued. page

Arrangement and distribution of the eggs and their attachment to the body . . 305

Origin of the egg glue and fixation of the eggs 306

The oviduct and its periodic changes 307

Comparisons with other Crustacea, and theories of fixation 308

The male sexual organs 312

Sperm cells, their origin and structure 312

Fertilization 315

The seminal receptacle, copulation, and impregnation 318

X. Development 320

Analysis of the course of development 320

Embryo 322

Exclusion and dispersal of the brood 326

Hatching process 327

First larva 329

Color of the larva 331

Structure and habits 332

Natural food of the larva 335

Second larva 337

Third larval stage 338

Fourth or lobsterling stage 340

Color in the fourth stage 341

Fifth stage 342

Sixth stage 344

Seventh stage 344

Eighth and later stages 346

Habits of adolescent lobsters 346

A lobster 413 days old 347

When does the young lobster go to the bottom to stay? 347

Food and causes of death in artificially reared lobsters 349

Significant facts of larval and later development 350

XI. Behavior and rate of growth 353

Behavior of young lobsters 353

Reactions to light 354

Reactions to other stimuli 356

Movements of the young lobster in a state of nature 357

Variation in the rate of growth and duration of the stage periods 358

Conditions which determine the rate of growth and duration of the stages. . . 359

Rate of growth and age at sexual maturity 360

XII. The preservation and propagation of the lobster 367

The fact and cause of decline of the fishery 367

The problem 369

How the problem has been met 369

Closed seasons 370

Protection of berried lobsters 370

The gauge law 371

The life rate or law of survival 375

Propagation of the lobster 379

Recommendations 382

Bibliography of the lobster — Homarus 384

INTRODUCTION.

The present work when originally undertaken in 1903 was designed to form the
zoological part of a history of the lobster in both America and Europe, but subsequent
events led to a modification of this plan, and when it was decided to issue this section
separately, its character and scope were somewhat changed.

Dr. Hugh M. Smith, of the United States Bureau of Fisheries, had planned to deal
with the lobster fishery and the economic questions which this great industry has
raised, in a comprehensive manner, and hope is entertained that this design may still
be carried out.

Though essentially a distinct work, this is in a measure both a revision and an
extension of rny earlier report upon The American Lobster, published by the United
States Commission of Fish and Fisheries in its bulletin for 1895. But little from the
latter, however, has been incorporated directly, and this only when newer or better
research has failed to give us more light upon the subject. Six drawings of the young
lobsters, three of which are in colors, have been reproduced, after slight revisions, from
my former report; all of the rest are new and deal chiefly with the anatomy of the body
and appendages, especially with torsion, reflex amputation, and the developmental
history of the toothed and cracker claws, the sexual organs, and the germ cells. I
have depended mainly upon the store of materials collected in former years, but have
received accessions from the United States Bureau of Fisheries, for which as well as for
many courtesies, now extending over a long period, I wish to offer my sincere thanks.
The Bureau has generously given me the privilege of a free lance, and all critical sections
of this paper should be read in the light of individual opinion only, directed, it is true,
in a friendly spirit, and as we believe from the standpoint of science.

Our knowledge of the lobster has increased to such an extent during the past
fifteen years that in all probability there is no marine invertebrate in the world which
is now better known. This result is due to the suggestive ideas or elaborate researches
of a large body of naturalists in both America and Europe, and to their labors the
reader will find abundant reference in the pages which follow. As a result of this advance
in the biological field, a signal success has been achieved in the artificial propagation
or culture of the lobster, and particularly in rearing the delicate young to the bottom-
seeking stage, a success from which this fishery should not be slow to profit, and which
it owes to experiments begun under the auspices of the United States Fish Commission
at Woods Hole, Mass., and afterwards carried to a high degree of perfection by the
Commission of Inland Fisheries of Rhode Island, under the direction of Prof. Albert D.
Mead, at Wickford. Through the aid of such a practical method there is ground for
hope, not only of restoring our depleted fisheries on the Atlantic coast, but of estab-
lishing new ones on the Pacific, as well as in other parts of the world.

153

154

BULLETIN OF THE BUREAU OF FISHERIES.

While many dark puzzles have been solved, and many questions, raised fifteen
years or more ago, can now be answered with assurance, no enterprising or resourceful
worker need be told that the field is still fertile for fuller or more exact researches in
many directions. We hope that some of these subjects will be suggested by the imper-
fections of the present work when attention is not called to them directly.

F. H. HERRICK.

Cleveland, Ohio.

BULL. U. S. B. F. 1 909

PLATE XXVIII

A.Hoe/l l GoflallimorB.

FIRST LARVAL OR SURFACE-SWIMMING STAGE OF THE LOBSTER

LENGTH 7.8 MM.

NATURAL HISTORY OF THE AMERICAN LOBSTER.

By FRANCIS HOBART HERRICK, Ph. D., Sc. D.,

Professor of Biology, Western Reserve University, Cleveland, Ohio.

Chapter I.— THE LOBSTERS AND ALLIED CRUSTACEA; THEIR ZOOLOGICAL
RELATIONS, HABITS, DEVELOPMENT, AND USE AS FOOD.

NATURAL HISTORY OF THE CRUSTACEA.

Nature works according to definite principles, and with a degree of uniformity which
for most of our purposes is practically absolute. Accordingly we find that whenever
an animal or plant has been successfully domesticated or whenever the young of any
form have been successfully reared by the artificial impregnation and subsequent care
of the eggs, as in the case of the oyster or the whitefish, this has been accomplished by
acting, whether intelligently or not, in accordance with the principles of nature. The
mollusk or the vertebrate is made to yield to experiments which a knowledge of its
habits and structure would suggest. In the lobster we have to deal with another and
distinct type, for although this animal swims in the sea, it is not a fish, but an arthropod,
and a knowledge of the ways of fishes and mollusks will help but little in the study of
its habits or in the propagation of its race.

The following paragraphs on the general characteristics of the arthropods will be
of little dr no use to professional zoologists, but may help to set our subject in a clearer
light for other readers.

Of the eight or more animal types recognized by naturalists the arthropods are
distinguished for their complicated structure and wonderful diversity of form, for the
wide range and specialization of their instincts, their almost unparalleled fertility and
corresponding activity. In the latter respect, at least, some of the insects are not sur-
passed by birds, the most active vertebrates.

The body of the arthropod is composed of a series of successive segments, the
somites or metameres, which in conformity to vertebrate anatomy are divided into three
groups, pertaining to the head, thorax, and abdomen. (PI. xxxm, and table 4.) Theo-
retically, each somite at one time possessed a pair of jointed limbs, and many of the seg-
ments still retain them. In the living adult state, the body is normally maintained in a
definite upright position, which is often one of unstable equilibrium, whether the animal
is in motion or at rest. These characteristics are shared in some degree by the annelid

I55

156

BULLETIN OF THE BUREAU OF FISHERIES.

worms, their nearest allies, as well as by the vertebrates. The arthropod possesses in
addition a dorsal brain, united by a ring-commissure about the esophagus, to a ventral
chain or “ladder” of paired ganglia, a character also shared by the higher worms; the
heart is dorsal and overlies the food canal; the cuticle, which encases the body and lines
every inward fold, is secreted by the outer layer of the skin, the epidermis or hypodermis,
and is chitinous — that is, contains chitin, a complex nitrogenous substance, by some
chemists regarded as analogous to cellulose and lignin, which occur typically in plants
and form the basis of all their woody tissues. This cuticle of the Crustacea is often rein-
forced by thick deposits of lime and other minerals, thus forming a hard external skeleton,
to which every peripheral muscle is directly or indirectly attached, and by which every
soft and delicate organ in the entire body is protected. No other animals possess all the
several characteristics just enumerated. Since the arthropods embrace the insects, with
their hundreds of thousands of species, it is not surprising that according to some
estimates they include three-fourths of all the known species of living animals.

Of the five commonly recognized classes of arthropods the Crustacea are the lowest
and most primitive. They fall into two principal subclasses: (a) The Entomostraca,
embracing all the simpler, more primitive and generally smaller forms, such as water
fleas, copepods, and barnacles, and (6) the Malacostraca, to which pertain the larger
and the most highly organized of living Crustacea, such as lobsters, shrimps and crabs.
The ancient name of the class served the older zoologists to distinguish those animals
which possessed a “crust,” or a shell flexible at certain joints, from the Testacea, or
animals like the oyster and clam in which the shelly covering was a hard and unyielding
“test. ”

Eight orders of Malacostraca “ have been recognized, of which the more important,
in view of their size, numbers, economic and general zoological interest, are the Amphi-
poda and Isopoda, which embrace the beach fleas on the one hand and terrestrial wood
lice on the other; the primitive Stomatopoda, of which the edible mantis or “praying”
shrimp are well known representatives, the small Schizopoda, or cleft-feet, and the
ten-footed and stalk-eyed Decapoda, which mainly interest us.

In both the isopods and amphipods the eggs are carried in a brood chamber on the
underside of the thorax, formed by membranous plate-like outgrowths from the thoracic
legs in the female; the schizopods also carry their eggs in a similar way.

The breeding habits of the stomatopods are highly peculiar; although celebrated
for their widely dispersed pelagic larvte, and although it was understood that they
dwelt in mud burrows under water, and did not carry their eggs attached to the body as
in decapods, little was known of their early life history until the studies of Professor
Brooks upon Gonodactylus chiragra of the Bahama Islands appeared in 1893, when he
gave the first full account of their habits, and the first record of the rearing of a young
stomatopod from the egg. Fortunately this animal does not deposit its ova deep in the
mud, but in a burrow, apparently of its own making, in the soft coral rock; they are
glued together by a viscous cement and molded to fit the convex form of the mother’s

a In the classification briefly outlined in this chapter we shall follow mainly the excellent work on Crustacea by Geoffrey
Smith, in vol. iv of the Cambridge Natural History. London, 1909.

NATURAL, HISTORY OF AMERICAN LOBSTER.

157

body. With its egg cluster on its back Gonodactylus stands or sits on guard at the
mouth of the burrow, awaiting its prey, and meantime keeping its eggs aerated by the
fanning movements of the swimmerets. Says Professor Brooks:

When the burrow is broken open she quickly rolls the eggs into a ball , folds them under her body
in a big armful, between the large joints of her raptorial claws, and endeavors to escape with them to
a place of safety. The promptness with which this action is performed would seem to indicate that
it is an instinct which has been acquired to meet some danger which frequently presents itself.

‘ J The decapods have the general characteristics given for the lobster in chapter vi.
All glue their eggs to their swimmerets and carry them thus attached, protecting and
aerating them for a period of weeks or months with unerring instinct until they hatch.
After pairing, the sexes frequently separate, as is possibly the case with lobsters (see p.
302), or they remain together, swimming side by side, and receiving mutual aid as in
Stenopus, for as long at least as the period of fosterage lasts. The young, upon hatching,
usually either swarm together for a time, or are immediately dispersed, as in the lobster.
A long and perilous metamorphosis awaits the young of most of the decapods, during
which they are pelagic or free surface swimmers, but every degree of abbreviation of this
development exists, and in the crayfishes and certain other species, both fluviatile and
marine, the young resemble the parent at birth, and a complex family life, which will
receive attention later, may be developed.

The decapods are divisible into three intergrading suborders: (1) The Macrura,
or long-tailed Crustacea like the shrimp and true lobsters; (2) the Anomura or hermit
lobsters and hermit crabs, and (3) the Brachyura or true crabs, the most highly special-
ized of the entire class, in which the tail is not only very short but is even rudimentary
in the male.

To follow out the Macrura only and in brief, they embrace numerous families
possessing both zoological interest and economic value, of which the most important are
(1) the Nephropsidse (Astacidse of many authors) or true lobsters; (2) the fresh-water
crayfishes of the world, or Astacidse of North America and Europe, and the Parastacidae
of the Southern Hemisphere; (3) the other decapods known collectively as prawns or
shrimps, including the Peneidae, Alpheidae, Pandalidae, Crangonidae, and Palaemonidae ;
(4) the Palinuridae, variously known as spiny, thorny, or rock lobsters, and (5) the Scyl-
laridae, which are sometimes classed with the Galatheidae, and are known as warty lobsters.
Representatives of some of these families will now be briefly considered, before dealing
more fully with the special subjects of this work embraced in the family of Nephropsidae.

The crayfish (of the family Astacidae) has become a favorite subject in zoology,
and very few invertebrates have received the degree of attention which naturalists have
paid to every phase of its history. It is well known that the common crayfish, Astacus
fluviatilis, has been used for centuries as food all over the continent of Europe, while
in France the farming of crayfish in order to increase the natural supply of this crus-
tacean has been successfully practiced for some time. For many years also crayfish
have found their way to the markets of American cities which possess large populations
of foreign birth, as New York, New Orleans, Chicago, Milwaukee, and San Francisco;
but many persons would probably be surprised to learn the present status of the Cray-

158

BULLETIN OF THE BUREAU OF FISHERIES.

fish industry in this country, where vast numbers are not only eaten but used to supply
classes in zoology or some phase of nature study in nearly every State of the Union.

Professor Andrews,® from whose paper the following statistics are taken, thinks
that the demand for the fluviatile crayfish is likely to grow steadily, and may help to
counterbalance the waning supplies of marine food, especially in the form of lobsters
and crabs.

The crayfish of the eastern central regions belong to the genus Cambarus, the Poto-
mac supplying C. affinis; Chicago, C. virilis; New Orleans, C. blandingii; and Montreal,
C. bartoni. A considerable fishery for the large and handsome American species of
Astacus, a counterpart of the European form, has been developed on the Pacific coast.
This centers in Portland, Oreg., where, in 1899, the product reached 117,696 pounds,
valued at $19,556.

Andrews has shown that the common Cambarus affinis not only breeds annually,
but that its young reared from spring eggs may in turn lay eggs the spring following,
when under a year old, while at the age of 3JJ years they attain the average market
size of 4 inches. It is further suggested that the large 6-inch Oregon Astacus, which is
more lobster-like in appearance, could doubtless be successfully introduced into Eastern
waters, and, with a growing demand, profitably reared, since there is no reason to
suppose that climatic changes would offer any obstacle to its development.

The prawns and shrimps distributed among the various families enumerated are
undoubtedly the most active and most graceful, as well as the most plentiful of all the
decapod Crustacea. Many species are highly valued as food, and are netted and sent to
market in vast numbers over a large part of the world. The most important shrimp
fisheries of the United States center in the Coast States of the Gulf of Mexico and
Pacific Ocean.

Among the best-known species in North America are the edible shrimp of the South
(. PencBus setiferus and P. brasiliensis ) , the still more abundant common shrimp ( Crangon
vulgaris), found on both coasts and closely related to the common European shrimp
The California shrimp ( Crangon jranciscorum) , the largest and most important of the
edible species on the western coast, attains a length of 3 inches. It not only supplies
abundantly the local markets, but occupies an important place in the export trade of
San Francisco, being boiled, dried, and shipped to China in large quantities.

Prawns are extremely abundant in the East Indies from Japan to Australia, and,
commercially considered, are the most important Crustacea of the Orient. Thirteen
species of the genus Penceus alone are taken in Japanese waters. “They are highly
prized and extensively used as food and bait, and dried prawns annually exported to
China amount to about 900,000 kilograms in weight and to about 200,000 yen
($131 ,000) in value. The dried prawns belong almost exclusively to the genus Penceus.”b

Closely allied to prawns, though placed in a distinct family, are the Alpheidae, of
which over 100 species of snapping shrimps belonging to the genus Alpheus and
Synalpheus alone have been described. They are essentially tropical, and abound in

a Andrews, E. A.: The future of the crayfish industry. Science, n. s., vol. xxin, 1906, p. 983-986. New York.

^Kishinouye, K.: Japanese species of the genus Penaeus. Journal of the Fisheries Bureau, Tokyo, vol. vm, 1900, no. 1, p. 1-29.

NATURAL, HISTORY OF AMERICAN LOBSTER.

159

the coral seas of both hemispheres. The Alpheidse have no commercial value, but
are of great biological interest, on account of their wide variation in form, coloring,
and development, as well as for their remarkable instincts and habits.

The large and handsome spiny or thorny lobsters (family Palinuridae) are repre-
sented chiefly by the single genus Palinurus. The langouste of the French, which has
been celebrated from antiquity, is noted for its great size, brilliant coloring, and formi-
dable appearance, though claws are lacking, as well as for its small and numerous eggs
and grotesque transparent larvae. Its flesh, which is mainly confined to the thorax
and tail, is considered by many quite as delicate as that of the true lobsters. From
13 to 16 species have been described from the temperate and tropical seas of the world.
According to Spence Bate,® this genus is represented in the South Indian Ocean by
Palinurus edwardsii, the range of which extends from the Cape of Good Hope to New
Zealand, by Palinurus trigonus and allied forms in Japan, by Palinurus frontalis on the
coast of South America, and by Palinurus longimanus and related species in the West
Indies. The common spiny or rock lobster ( Palinurus vulgaris) of southern and western
Europe is an important article of marine food, particularly in France and on the coasts
of the Mediterranean Sea and its islands. It is commonly seen in the markets and
restaurants of Eondon, where it commands a good price.

According to Ritchie,* * 6 Palinurus vulgaris occurs on all the shores of the British
Isles except a part of the east coast to the north of Flamborough Head. It is most
abundant in the southwest, and scarcer northward, but is frequently debarred from
entering traps on account of its stout, unyielding antennas. Palinurus in the adult
state is unknown in the North Atlantic Ocean north of the Bermuda Islands, but its
pelagic larvae are undoubtedly borne far to the northward by the Gulf stream. It
is represented on the western coast of North America by Palinurus interruptus.

The carapace of the langouste is not “buttoned” to the tail so effectively as in
the common lobster; all the thoracic legs end in long dactvls with indurated tips,
which are studded with dense bunches of stiff setae. The first two pairs of legs are
greatly elongated, and the tactile setae of their dactyls, which resemble bottle brushes,
exhibit an extraordinary development.

The largest of the scaly or warty lobsters is represented by Scyllarus, which occurs
both in the Mediterranean and the North Atlantic Ocean, and is said to attain a length
of 18 inches and to excel all other lobsters in the quality of its flesh. Their quadran-
gular, flattened shell and small, slender legs give them a singular appearance, but
specially remarkable are the short, scale-like antennae, which are possibly used as
shovels or scoops in burrowing. Their small and widely separated eyes are completely
embedded in the carapace, which is studded all over with wart-like tubercles, thus
giving it a granulated and leathery texture, while on the inside it has the appearance
of a fine sieve of uniform pattern. Each hole gives passage to a bundle of tactile
setae, which spread in the upper layers of the shell and issue through minute pores

a Bate, Spence: Report on the Crustacea Macrura; Scientific results of the voyage H. M. S. Challenger; Zoology, vol. xxiv.

London, 1888. -

& Ritchie, James: Distribution of Palinurus in British waters. Proceedings of Royal Physical Society of Edinburgh, vol
xxm, p. 68-71. Edinburgh, 1910.

160 bulletin op tpie bureau of FISHERIES.

upon the tubercles or around their margins. The last pair of thoracic legs, in the females
only, bear claws, which led to the fanciful notion that they were used by the mother
in rupturing the eggs and liberating the young. The eggs are very small, and, as in
Palinurus, the young issue in the peculiar transparent larva known as phyllosoma.

The whole front of Palinurus guttatus is armed with stout spines culminating in
a pair of rostral horns, which in large specimens rise vertically to the height of an inch
or more in parallel planes, thus shielding the eyes and presenting one of the most effective
types of protective armature to be seen in an adult crustacean. The antennules are
extremely long and slender, while the antennae have very stout basal stalks, and long
stiff flagella, encircled at intervals with sharp teeth, like the war mace of a South Sea
Islander.

The second segment of the antenna bears a notable structure, usually described
as a stridulating organ. The inner surface of this division is free, and carries a pad
and flap which, with the movements of the antenna, plays backward and forward over
a smooth ridge or track on the somite. The sound, which it is said may be heard in
or out of water and may be produced artificially after death, is evidently caused by
friction of the hard chitinous surface of the pad on the track over which it slides.
(See p. 240.)

The California spiny lobster, according to Rathbun, may attain a length of 14
inches, and an average weight of 3 >3 pounds, the greatest weight recorded being iipZ
pounds. The usual length of Palinurus -vulgaris , as given by Bell ( 20)0 in 1853, was
about a foot, but 18 inches was sometimes reached. His description was from a male
of the latter size, which weighed 5 pounds. “I can not but think,” said Bell, “that
Dr. Milne Edwards is greatly mistaken in attributing to individuals of that size a weight
of from 12 to 15 pounds.” The Californian langouste is most abundant on the southern
part of the coast. It is often trapped in great numbers, but even twenty years ago we
are told by Rathbun that the species was in danger of extermination from overfishing.

Artificial propagation of the Japanese spiny lobster, Palinurus japonicus Gray,
was undertaken by the fisheries institute, near Tokyo, previous to 1899, and a report
of progress was published in that year. Great difficulty was experienced in handling
the larvae, on account of their minute size and long metamorphosis. The spawning and
hatching periods of this lobster, as I am informed by Tasute Hattori, who conducted
the experiments, extend from late April to late September. The larvae were easily
hatched, but gradually died off after the fifteenth or sixteenth day. No success had
been attained in 1901, since which time no further information has been received.

The Nephropsidae, the best known of the Crustacea, on account of their high com-
mercial value as food, are represented by three species, the Norwegian lobster, Nephrops
norvegicus Linnaeus, the common lobster of Europe, Homarus gam-mams Linnaeus,
and the common lobster of America, Homarus americanus Milne Edwards.

The technical names for the lobsters adopted in a former work (149) are here
retained, pending a decision upon the question by the International Committee on
Nomenclature of the International Zoological Congress, which met in Boston in 1907.

a Italic figures in parentheses refer to works enumerated in the bibliography at the end of this paper.

NATURAL HISTORY OF AMERICAN LOBSTER.

161

The question of the validity of Latreille’s types in his “Considerations Generates . .
of 1810, has been raised by Stebbing, who would restore the terminology of Leach, desig-
nating Astacus Potamobius and Homarus Astacus .a

Aside from the merits of this controversy, it may be well to point out again that
Latreille and others who have followed him were wrong in asserting that Aristotle makes
no mention of the river crayfish (149). O11 the contrary, the Father of Zoology uses

the term dozaiwc to designate both crayfish and lobster, and so far as antiquity is con-
cerned neither has the claim of priority.* * * * 6

The Norwegian lobster is common not only to Norway but to the coasts of Scotland
and Ireland. While essentially a northern form, it is found as far south as the Medi-
terranean but in much less abundance. It attains a length of from 7 to 8 inches, and
in life is of a delicate flesh tint, boldly marked with light brown in symmetrical pat-
tern over the abdomen and tail fan. Its slender form suggests the shrimp type, and
its large kidney-shaped eyes remind one of Penceus, and of the adolescent lobster
( Homarus ) when from x to 3 inches long. The claws of the first pair of thoracic legs are
slender, of nearly equal size and keeled above, below, and at the sides, each keel having
a single, or at the sides a double row of spines. Bell, writing at the middle of the last
century, said of this species that it was frequently on sale in the Edinburgh markets,
and was occasionally seen in London.

The European lobster is found on the shores of the British Islands, and on the
western coast of Europe from Norway to the Mediterranean. The southwestern coast
of Norway appears to be the central point of its distribution and still supports the
largest of the European fisheries, but the species is found northward as far at least as
Tromso, or to about 69°-7o° north latitude. (See 306.) It is very rare, if present at
all, in Iceland. It does not appear to enter the Baltic, and is not common in the
Mediterranean, being limited in its eastern range by the Adriatic Sea. In Great Britain
it is chiefly confined to certain districts on the west and north coasts.

Of the three kinds of lobsters already described for the Atlantic and its tributaries,
the Norwegian and common lobsters are typical northerly forms, while the langouste
or Palinurus abounds only in the south. The best fishing grounds for the common
lobster in the Scottish seas are said to be the Orkney and Outer Hebrides islands.

The common lobster of Europe resembles the American lobster so closely in every
structural detail that the two might at first sight be considered as geographical varieties
of the same stock rather than as distinct species. It has been pointed out that the under
side of the beak or rostrum is smooth in the Homarus gammarus, while in the American
form it is armed with a spine, a rather trivial distinction in view of the variable character

° This commission reported to the Congress, which met at Graz, August, 1910, in favor of accepting Latreille’s type desig-

nations. The term Astacus should therefore be restricted to the crayfishes, and the names stand as designated in the text.

See opinions rendered by the International Commission on Zoological Nomenclature. Publication No. 1938, Smithsonian Insti-

tution, Washington, 1910.

& Those interested in discussions of this character are referred to no. 225 and no. 260 of the bibliography at the end of this work,
and also to the following: Rathbun, Mary J., List of the decapod Crustacea of Jamaica, Annals of the Institute of Jamaica, vol.
1, no. 1, 46 p. Jamaica, 1897; Faxon, Walter, Observations on the Astacidse in the U. S. National Museum and in the Museum of
Comparative Zoology, with descriptions of new species, Proceedings U. S. National Museum, vol. xx, p. 643-694, Washington,
1898; Stebbing, Thomas R. R., The late lamented Latreille. Natural Science, vol. xn, p. 239-244. London, 1899.

48299° — Bull. 29 — 11 11

BULLETIN OF THE BUREAU OF FISHERIES.

162

of such structures. In fact, either one, two, or three spines of inconstant size may be
present in the American lobster, though this is a condition which in some cases might
be attributable to an injury and its imperfect repair. In the slight differences observed
in the development of the American form, however, there are more valid reasons for
maintaining the specific names.

It has been the accepted belief that the American lobster attains a greater size than
its European counterpart, but it is possible that in early days the maximum size was
essentially the same. The fishing of lobsters in Europe is of great antiquity, and the
average size of the adults taken has been reduced in consequence, while the industry in
this country has been mainly developed during the last hundred years. The same
gradual falling off in size, due to the same cause, has nevertheless been experienced
on the New England coast and in the maritime provinces. It seems certain, however,
that the American lobster has larger claws, and, length for length, it will weigh more
than the European form. (See chapter in, p. 195.)

The slight differences in the development of the two forms, already referred to, are
seen in the young at the moment of hatching. The abridgement of the larval period
has been carried a step farther in the common lobster of Europe, so that its young issue
from their eggs in a stage nearly comparable to the second larva of the American lobster.

DEVELOPMENT OF THE CRUSTACEA.

All the decapod Crustacea are developed from eggs which in the Macrura are fertilized
outside of the body and are generally carried until hatched on the under side of the tail
or abdomen of the female, where they are glued to certain hairs of the swimmerets.
The sperm cells are vesiculate and often “rayed.” The eggs vary in number from less
than a dozen, as found in small species of Synalpheus with abbreviated development, to
several millions, as in Callinectes and Palinurus, and from nearly \ inch, in certain deep
sea shrimp, to less than Tjjo inch in diameter.

The time of fertilization, so far as known, always coincides with that of oviposition
and attachment. By means of a liquid cement the eggs are fixed, in a way to be later
discussed, often to one another and always to the swimmerets under the abdomen. In
life the swimmerets beat rhythmically backward and forward, whether the animal is in
motion or at rest, and the attached eggs are thus constantly cleaned and aerated under
natural conditions.

The ova are delicate and soon die if cut loose and left to themselves. In order to
rear them successfully under such conditions, artificial aeration of some kind must be
resorted to and conditions devised to prevent the accumulation of sediment or parasitic
growths over the surfaces of the eggs. The best “brooder” of any decapod’s eggs is
undoubtedly the mother, whether lobster, shrimp, or crab.

The period of fosterage varies from a few days or weeks in some of the smaller
tropical decapod Crustacea to nearly a year in the lobsters. There is a similar variation in
the frequency of spawning; certain Alpheidae of the Bahama Islands apparently have a
succession of broods the year round, while others may lay their eggs twice or once only
each year. In the American lobster the breeding period is biennial, but it is possible

NATURAL HISTORY OF AMERICAN LOBSTER. 1 63

that successive annual broods are occasionally produced, as has been known to occur in
Homarus gammarus on the English coast, and after transplantation to New Zealand.

In many of the prawns the eggs all hatch in the course of a few hours, and at night
or very early in the morning, as I have observed in Pontonia, Stenopus, and Synalpheus.
The adult Pontonia lives in the mantle chamber of Pinna, a large bivalve mollusk. For
a day or two its young move about in a dense cluster like a swarm of gnats.

The young in most Crustacea are hatched in- an immature state, and in most species
they cut loose from the parent at once, proceed to the surface, and as pelagic larvae
lead an independent existence for days or weeks. Though as adults they may be
sedentary and chained to the bottom, as larvae they are usually most active, and it is
during this period of free swimming that they undergo their metamorphosis, or series
of changes by which most of their proper adult characters are acquired.

So remarkable are some of these larval changes, and so great is the difference of
degree in which they are expressed, even in forms so near akin as lobster, crayfish,
and prawn, that the fact when first affirmed was denied as incredible. The credit for
the discovery of the metamorphosis in Crustacea, which has proved to be a most fruitful
generalization in zoology, belongs primarily to a Dutch naturalist, who has not always
received his just dues, and secondarily to an Irish zoologist, for the old observations
of Martin Slabber,0 made June 24-28, 1768, and published with excellent drawings in
1778, were not followed up and fully understood until J. Vaughan Thompson confirmed
and completed them by studies began in 1822, continued for many years, and published
at various times from 1828 to 1843. The sea-waterflea or Taurus of Stier, which
Slabber figured and distinctly described as passing by metamorphosis to a different and
higher form, was afterwards regarded as representing an independent genus of animals
and renamed Zoe or Zoea by Bose* * * 6 in 1802.

Bell, who has given a very fair account of this subject in the introduction to his
work already referred to, thought that the zoea which Slabber had under observation
was the larva of the common ditch prawn Palcemon varians, later described by Du
Cane.

Very shortly Thompson obtained in abundance larvae resembling the Zoea taurus
of Bose by rearing the eggs of the common English crab, Cancer pagurus. Again in
1835, by extending his studies to the common green crab, Carcinus moenas, he
showed that it not only was hatched as a zoea, but passed from this larval state into
a megalopa before acquiring the true crab-like form and characteristics, proving that
this mythical genus which had been proposed by Leach was, like the zoea, only a passing
phase in the metamorphosis of the crab. Then it was shown that in the course of its
development from the egg the crab passed through two consecutive stages which were
so unlike each other and so unlike the adult form that former naturalists had placed
them not only in different genera but in different families.

0 Slabber, Martinus. Natuurkimdige Verlustigingen behelzende Microscopise Waameemingen van In-en Uitlandse Water-

en Land-Dieren. Waarneeming van een Zee-Watervloo, genaamd Taurus of Stier, v. stukje, 5 plaat, p. i-xn, 1-166, pi. 1-18*

Haarlem, 1769-U778.

& Bose et Desmarest, Manuel de l’histoire naturelle des Crustaces, t. n, p. 237. Paris, 1830.

BULLETIN OF THE BUREAU OF FISHERIES.

164

Few general laws are without exceptions, and the fact that metamorphosis, which
is even more common in Crustacea than in insects, is sometimes scamped or wanting
altogether, led at once to confused and contradictory ideas. The abbreviated larval
history of the crayfish which had been worked out with great care by Rathke in 1829
and that of the European lobster first announced by Thompson ( 262 ) in 1831, and
confirmed by Brightwell in 1835, as well as that of the West Indian shore crab,
Gegarcinus ruricola, determined at the same time by Westwood, led to temporary
difficulties, which were eventually cleared away when the development of many kinds
of both macruran and brachyuran Crustacea had been studied with sufficient care.

It thus appears that the term “zoea” was first applied to the larva of a prawn and
crab, in which the swimming appendages are three pairs of claw feet or maxillipeds,
the thoracic legs being rudimentary buds when represented at all. The abdomen is
segmented, but bears no appendages and ends in a forked telson. There is a long
depressed rostrum and a very long and sharp dorsal spine ivhich springs from the
middle of the carapace, both of which seem to be admirably adapted for protection.
Though many variations occur in the larvae of closely related genera and it is difficult
to make general terms fit the varying degrees of modification which larvae have under-
gone, it seems best to preserve the historical usage of the word zoea as far as possible.
For this reason we speak of the young lobster when hatched with its thoracic appen-
dages well formed and using both its great maxillipeds and following thoracic legs for
swimming simply as a larva rather than as a zoea, however modified.

Most true crabs and prawns hatch as zoeas from minute eggs, and are commonly
translucent and flecked with brilliant red and yellow pigment cells. They molt fre-
quently during the first few weeks of life, passing in the case of crabs through a megalops
stage, and then gradually assuming the structure and habits of the adult animal.

Entomostraca generally, and exceptionally certain of the Malacostraca, such as the
decapod Penceus and the schizopod Euphasia, hatch from eggs still more minute and
in a much simpler larval form called the nauplius. It is unsegmented, possesses but
three pairs of appendages, representing the antennulas, antennae, and mandibles of the
adult, and has a single median “nauplius” or “Cyclopean” eye. Upon the theory
of recapitulation, the nauplius has been regarded as the representative of a primitive
or ancestral form, but it seems more probable that existing larvae of this type have
become modified to meet the present conditions of their environment.

In every metamorphosis individuality is preserved from egg to adult, and develop-
ment proceeds according to this simple formula : Egg = embryo = larva 1,2,3+= adolescent

(gcrcrs or
sperm

A long metamorphosis which entails a long pelagic life near the sunace means greater
risk and greater destruction than one of short duration. Consequently it is not surpris-
ing to find a general tendency to shorten this larval period, reducing the metamorphosis
by shifting it to the egg, or, more exactly, by lengthening the period of egg development.
In this case the supply of food yolk is increased to support a longer life within the egg
membranes, and the larvae or young issue in a more advanced state, and as a rule have

NATURAL HISTORY OF AMERICAN LOBSTER. 1 65

a shorter pelagic period. The size of the individual egg is increased, but the number
of eggs is diminished. The alternative lies between two extremes as follows:

(Eggs small, but many of them.

Long metamorphosis.

Less chance for individual survival, but more individual chances.

(Eggs large, but few in number.

Metamorphosis shortened.

Greater chance for the individual, but fewer individuals to take it.

Between these two types of adjustment many compromises have been made. The
principal larval stages or types in decapods which have received definite names, being
the survivals in some cases of a period when crustacean larvae were considered adult
forms, are the following:

(1) Nauplius and metanauplius. The shrimp Penceus is hatched as a nauplius and
passes through the metanauplius, first and second protozoea, first and second zoea, and
mysis stages, before attaining the adult form. Lucifer hatches as a nauplius, molts
into a metanauplius stage, with buds of three more appendages present ; then passes
successively through the protozoea, zoea, schizopod or mysis, and mastigopus stages,
and finally to the adult.

(2) Protozoea, zoea, and metazoea. The shrimps Sergestes and Stenopus hatch as
protozoeas, and pass the successive stages as given for Lucifer.

In the protozoeas the antennae are large and are often used in swimming; the
carapace is formed, and the abdomen is unsegmented or but incompletely marked off
into somites. The telson is forked and garnished with plumose setae.

A protozoean stage has been assigned to the lobster, but erroneously, as will be later
explained.

The zoea characteristic of the crabs has seven pairs of appendages and a segmented
abdomen. The last two pairs — first and second maxillipeds ( Callinectes ) — are swimming
feet, which in the adult are converted into mouth parts. Many shrimp are hatched as
modified zoeas with three pairs of locomotor maxillipeds, and the abbreviation is carried
a step farther in some species of Synalpheus (S. minus) where buds of three pairs of
thoracic limbs appear behind the maxillipeds, and still farther in others (S. bremcarpus),
where the first young to appear are in a “mysis” stage similar to the second larva of
the lobster.

(3) Megalopa. The changes which follow in the early development in the crab
zoea lead first to the metazoea, with rudimentary thoracic limbs and pleopods, and
then by a sudden leap to the megalopa, a form comparable to the fourth stage of the
lobster. The megalopa has large, free, stalked eyes, large claws, and functional walking
legs. The swimming exopodites or outer branches of the maxillipeds have atrophied
and disappeared, and like a lobster from the fourth stage onward, it has a segmented
abdomen with functional swimmerets. It has also well-developed statocysts or balanc-
ing organs and no longer reels in its motion through the water by day, but maintains a
definite, upright position. In the course of succeeding molts the abdomen becomes
reduced and modified, while the animal acquires the peculiar structure and habits of

1 66

BULLETIN OF THE BUREAU OF FISHERIES.

the adult crab. The development is abbreviated in the Gegarcinus ruricola, the gaily
colored terrestrial crab of the West Indies, the large eggs and young of which were
a puzzle to the early observers.

(4) Mysis or schizopod stage. The biramous condition of the thoracic legs char-
acteristic of this stage is transitory in the larv® of the higher Crustacea, but perma-
nent in the lower order of schizopods. The oar-like exopods of the larval thoracic
appendages persist in the lobster until the fourth molt, when they are suddenly reduced
to rudiments, and after the fifth stage no vestige of them remains.

(5) Larval period reduced in various degrees, and metamorphosis in some cases
practically absent. In addition to the crayfishes, lobsters, and other illustrations of
abbreviated development already given, we may mention Synalpheus longicarpus of the
West Indies as a striking example, in addition to certain fluviatile and many deep-sea
forms.

Like other animals, the Crustacea tend to recapitulate in some degree the history of
their ancestors in the course of their own development, and to become modified in
structure and instincts to fit them for a temporary pelagic life which is totally unlike
that assumed when adult. Their history is further complicated, as has just been seen,
by the tendency to abridge the larval period or lengthen the time spent in the egg.

Shortening the path of development is not a peculiarity of arthropods, but is
common with both vertebrates and invertebrates. It depends in a large degree upon
the relative amount of food yolk and protoplasm of the egg cell, both of which are
derived from the parent, and primarily upon the unknown variations and conditions
which have led to this result. The size of the egg is proportional to the amount of yolk
which it contains, not the size of the animal producing it. Thus the egg of a snapping
shrimp 1 to 2 inches long may be many times larger than that of the lobster, while the
egg of the latter is hundreds of times larger than that of the blue crab. When the
amount of yolk is small, as in the egg of the starfish or spiny lobster, the young hatch
in an immature condition; at the other extreme, when the egg is relatively large, as in
the crayfish or domestic fowl, the whole period of early development is passed at the
expense of the egg substance, and within its envelopes. The chick hatches in the form
and with many of the instincts of an adult bird, ripe for the experience of bird life and
capable of using it with profit.

The yolk retards the progress of development up to the time of hatching, but
greatly shortens the adolescent period. The chick of the domestic fowl spends 21 days
in the egg, but in the hands of the poultry breeder it may later attain the weight of xpi
pounds in 3 months, when it is ready for market.

On the other hand, the egg of the starfish or sea urchin, which is unencumbered by
a great mass of yolk, and very small in consequence, measuring about inch in
diameter, hatches at ordinary temperatures in 24 hours. It must, however, lead a long
life as a larva, make its own living, run the gauntlet of enemies, and keep up the struggle
for months. Thus the handicap at the start may count for little in the end. The
advantage gained by the fowl in having a few very large eggs is offset by that of a vast
number of almost microscopical ova in the echinoderm.

NATURAL HISTORY OF AMERICAN LOBSTER.

167

In the lobster the conditions of development are intermediate between such
extremes, but in weighing them the structure and habits of the animals at every stage,
the environment, and their adjustment to it must be considered. The whole period of
development is long, followed by a long period of adolescence, but the relative duration
of the swimming life, which is about 3 weeks, is shorter than in the starfish or in
Palinurus (see p. 160). This is a fortunate circumstance in view of the possibilities of
artificial propagation, as will be later seen.

While the abbreviation of the metamorphosis is attended by an accumulation of
yolk in the egg, it is impossible to explain either how this has been effected or why in
any case such a course should have been followed to secure greater harmony or fitness
to the environment.

In fresh-water forms and in deep-sea species the shortening of the metamorphosis
may be more uniform and the advantage derived more apparent. In all cases, however,
it is a question of the survival of the young, but no one can say why in Palinurus the
problem has been solved by increasing the number of individual chances and in the lob-
ster by lengthening the period of fosterage and reducing that of the larva. In any case
the tax on the parent, when no parental instinct is involved, is essentially the same,
though the items are changed, since the total amount of food yolk manufactured in the
ovaries of a crab, which lays millions of eggs, is probably not relatively greater than that
produced in the organs of the lobster, whose eggs are counted only by tens of thousands.
The greater the size of the egg, however, the longer is the tax issue upon the energy of
the young deferred and the greater the reduction of its rate.

The adjustment represented by either extreme is certainly advantageous in the
long run, but probably neither is the best under all circumstances.

FAMILY LIFE IN CRAYFISH.

The crayfishes, which are now all inhabitants of fresh water or burrowers in soil
where moisture is available, are undoubtedly descended from marine lobster-like
ancestors, and, as we have seen, for reasons not fully understood have undergone a
still greater reduction in larval development. They have, further, acquired an inter-
esting family life, which was noticed by Rosel von Rosenhof over one hundred and fifty
years ago. An adequate account of this relation has finally been given by Andrews,3
and in concluding this chapter we shall give a resume of one phase of it, based upon his
work.

Metamorphosis has been curtailed to such an extent in Astacus and Cambarus that
they are hatched in a form which suggests the fourth stage of the lobster. In reality
the young crayfish presents a curious compound of embryonic, larval, and adult char-
acters. The peculiar family relation which serves to tide the young over a helpless
period of infancy to complete independence endures, according to Andrews, for about
a fortnight, or until after the second molt in Astacus and after the third in Cambarus.

a Andrews, E. A. The young of the crayfishes Astacus and Cambarus. Smithsonian Contributions to Knowledge, vol.
xxxv, no. 17, 18, p. 1-80 ; pi. i-x. Washington, rgo7.

BULLETIN OF THE BUREAU OF FISHERIES.

1 68

It is dependent upon a complicated chain of events, which suggests the story of the old
woman who went to market to buy a pig. Thus if the egg stalk in Astacus does not
adhere to a “hair” of the parental swimmeret or to another egg; if the two egg shells
are not themselves adherent; if a certain delicate thread, which is spun, as it were,
from an embryonic cuticle shed at hatching time, does not itself stick on the one hand
to the telson of the young and on the other to the inside of the inner egg shell, and thus
tether the little one to its mother; if again, a little later, when its leading string has
broken, this young one has not been enterprising enough to hook on to some part of
the egg glue with its great forceps, the tips of which have been bent into fishhook form,
it comes to certain grief. The result is fatal at whatever point the chain weakens and
snaps.

A few hours after hatching, the helpless little crayfishes, still dangling from the
“telson threads” which secure each to the parent, begin to flap their abdomens and to
open and close their big, hooked claws. In this way they manage to seize the old stalk
of the egg and, with hooks embedded in its tough chitinous “glue,” they hold on, liter-
ally for dear life, often grasping the same stalk with both chete.

At the second molt this crayfish is for the first time free, and soon begins to descend
the parental pleopod, climbs over its mother’s body, and makes short excursions in the
neighborhood, returning again and again to the alma mater and the family brood.
Hitherto it has been sustained solely by the generous amount of yolk inherited from its
egg state, but since the egg stalks and cases, as well as the cast-off skins, which were
attached to the mother, disappear at this time, it is thought that they are eaten bv the
'young and constitute the first direct food they receive before beginning to forage for
themselves.

In Astacus the “telson thread,” according to Andrews, represents an embryonic
molt or cuticle, and the abdominal part is turned inside out at the time of hatching
and drawn out into the thread, the cuticle sticking on certain of the median marginal
spines of the telson. The newly hatched Cambarus is tethered to its mother in a some-
what similar way by means of the partially inverted and telescoped “lost larval cuticle,”
which is shed at hatching and is in this instance an “anal thread,” since it sticks at two
points only — on the side of the mother to the egg membranes, which are adherent to
her, and on that of the young Cambarus to a portion of the intestine where its cuticular
lining is at first set free. As a result of the tension this embryonic molt is stretched
and crumpled, with a tendency to turn the abdominal part inside out. This telescoping
and partial inversion of the discarded cuticle is checked only by the molted plate of the
telson, with the resultant production of a narrow creased ribbon, the “anal thread,”
which is firmly fastened to the intestinal wall.

Chapter II.— THE AMERICAN LOBSTER: ITS ECONOMIC IMPORTANCE AND

GENERAL HABITS.

White men caught lobsters in Massachusetts Bay for the first time early in the
seventeenth century. The Pilgrims and Englishmen who began to flock into the bay
colony about the year 1630 were well acquainted with the products of the sea in their old
home, and the coast of New England supplied their tables with essentially the same
kinds, only in far greater abundance. It is said, indeed, that the Pilgrims began at once
to pay their debts, due in England, out of the products of their fisheries.

In the chronicles of those early days the lobster is honored with frequent mention,
and the early colonists must have enjoyed to the full both the new and the familiar
kinds of American fish, lobsters, crabs, and clams, so big, so palatable, so abundant, and
so cheap everywhere along that coast. Indeed, one would think there was no need of
starvation, with lobsters and the other forms of sea food to be had on every shore. To
quote from Mrs. Earle (80), the minister, Higginson, writing of Salem lobsters, said that
many weighed 25 pounds apiece, and that “the least boy in the plantation may catch
and eat what he will of them.” Again, in 1623, when the ship Anne brought over many
of the families of the earlier Pilgrims, the only feast of welcome which the latter had to
offer was “ a lobster, or a piece of fish, without bread or anything else but a cup of spring
water.”

The Pilgrim lobsters “five or six feet long,” ascribed to New York Bay, take us
back one hundred years further, to the time of Olaus Magnus. In a tabulated list of
some fourteen of the biggest lobsters ever captured on the Atlantic coast (no. 9, table
1, p. 195) for which authentic weights or measurements have been preserved, the giant
among them all weighed 34 pounds, and measured exactly 23 inches from spine to tail.
No doubt the Pilgrims would measure a lobster as some fishermen do now, with the big
claws stretched to their fullest extent in front of the head. In this condition the actual
length of the animal is about doubled, so that the length of the New Jersey record
breaker, when distended in this way, would reach nearly 4 feet, and the Pilgrim 6-foot
lobsters have probably been stretched nearly a yard. (Compare fig. 1.)

In an account of marketing in Boston in 1740, “oysters and lobsters” are mentioned,
“in course the latter in large size at 3 half-pence each,” and this abundance continued
for over one hundred years.

To revert at once to modern times, many no doubt remember when lobsters were
sold by the piece, and at a few pennies at that. Five years ago, with a market price of
25 cents per pound, a lobster weighing 3 pounds 9 >4 ounces, at an inland market in New
Hampshire, cost 90 cents. The clear meat of the claws and tail of this animal,
which had a fairly hard shell, were found to constitute but 27 per cent of the whole.
(See table 3, p. 214) This would bring the cost of such meat to 90 cents per pound.

169

170

bulletin of the bureau of fisheries.

Even when every edible part of this animal was saved, which is seldom or never done,
the total waste was found to be 45 per cent, and the cost of all edible parts 45 cents per
pound. At the present retail prices of from 30 to 35 cents per pound, these estimates
would have to be considerably increased.

GEOGRAPHICAL RANGE OF THE AMERICAN LOBSTER.

The American lobster ( Homarus americanus) is found only on the eastern coast of
North America. Its geographical range covers about twenty degrees of north latitude,
from the thirty-fifth to the fifty-second parallel, and embraces a strip of the North
Atlantic Ocean 1,300 miles long and 30 to 50 miles wide, and according to one estimate
7,000 miles in length when measured along the curves of the shore. Its vertical distri-
bution varies from x to over 100 fathoms. The most northern point at which its capture
has been recorded is Henley Harbor, Labrador (209) ; the most southern point, the coast
of North Carolina.0 Since the fishery was begun on the southern New England coast
and was gradually extended northward, it is not surprising to find the lobster at the
present time not only more abundant but attaining the greatest average size in the north-
erly parts of its range — in eastern Maine and the Maritime Provinces. It should be
noted, however, that three of the largest lobsters captured in recent years are from New
Jersey. (See fig. 1 and table 1, p. 195.)

HISTORY AND IMPORTANCE OF THE LOBSTER FISHERIES IN BRIEF.

According to Dr. Richard Rathbun (227), who was the first to give us a history of
the American lobster fisheries, this fishery as a separate industry began toward the close
of the eighteenth or the beginning of the nineteenth century, and was first developed
on the coast of Massachusetts and in the region of Cape Cod and Boston, some fishing
being “done as early as 1810 among the Elizabeth Islands and on the coast of Connect-
icut.” “Strangely enough, this industry was not extended to the coast of Maine,
where it subsequently attained its greatest proportions, until about 1840.”

The early white men learned many lessons in fishing from the Indians, and those
living upon the coast in the course of time began to supply settlers more remote, until
the Cape Cod region, having become famous, attracted fishermen with their smacks from
Connecticut and from other states, and furnished most of the lobsters consumed both
in Boston and New York for fifty years, or until the middle of the nineteenth cen-
tury. In 1812, as Dr. Rathbun remarks, the citizens of Provincetown, realizing the
danger of exhausting their fishing grounds, succeeded in having a protective law enacted
through the state legislature, apparently the first but not the last of its kind, for legal
restrictions, including this statute, have been in force ever since. But this measure
was designed to protect the fishermen rather than the lobster, for it was merely declared

a So far as known, the lobster has been taken but four times on the North Carolina coast during the pastfortv years, namely;
One lobster in 1870 at Beaufort; one dredged by the Albatross in 1884 off Cape Hatteras in 30 fathoms; one said to have measured
18 inches, caught in a gill net at Nags Head in 1903 and exhibited for some time as a curiosity at Elizabeth,Virginia;and another,
as noted by J. N. Cobb, was caught by a fisherman at Oregon Inlet, presumably not far from the latter date. For the last two
notices I am indebted to Dr. H. M. Smith of the U. S. Bureau of Fisheries.

NATURAL HISTORY OF AMERICAN LOBSTER. 171

illegal for anyone not a resident of the Commonwealth to take lobsters from Province-
town without a permit. The laws later enacted proved of little or no avail; by 1880 the
period of prosperity had long passed, and few lobsters were then taken from the Cape.
Only eight decrepit men were then engaged in the business, and were earning about $ 60
apiece. This great local fishery was thus rapidly exhausted by overfishing, and it has
never recuperated.

The history at Cape Cod has been repeated on one and another section of the coast,
from Delaware to Maine, and is already well advanced in the greatest lobster fishing
grounds of the world, the ocean and gulf coasts of the British Maritime Provinces of
Canada, especially of New Brunswick and Nova Scotia, and in Newfoundland.

Every local fishery has either passed, or is now passing, through the following
stages :

1. Period of plenty: Lobsters large, abundant, cheap; traps and fishermen few.

2. Period of rapid extension: Beginning in Canada about 1870, and much earlier
in the older fishing regions of New England; greater supplies each year to meet a growing
demand; lobsters in fair size and of moderate price.

3. Period of real decline, though often interpreted as one of increase: Fluctuating
yield, with tendency to decline, to prevent which we find a rapid extension of areas
fished, multiplication of fishermen and traps and fishing gear or apparatus of all kinds;
decrease in size of all lobsters caught, and consequently of those bearing eggs; steadily
increasing prices.

4. General decrease all along the line, except in price to the consumer, and possibly
in that paid the fisherman.

The official statistics for the State of Massachusetts and for Canada afford pertinent
illustrations of the older and newer phases of this history. Thus, in Massachusetts in
1890, 373 fishermen, working 19,554 traps, caught 1,612,129 lobsters of legal size and
70,909 egg-bearing females, with an average catch per pot of 82. Fifteen years later it
required 287 fishermen, using 13,829 traps, to produce about one-quarter of this number,
or 426,471, and less than one-seventh the number of egg-lobsters, or 9,865; while the
catch per trap had diminished by nearly two-thirds, and was only 31. No substantial
increase followed until 1907, when the legal length was reduced to 9 inches, and this was
undoubtedly due to the large number of small lobsters caught.

The total product of the lobster fisheries in the United States for 1892 was
23,724,525 pounds, about three-fifths of which were furnished by Maine, and valued
at $1,062,392. It is significant to notice that thirteen years later, in 1905, the total
yield, according to Dr. Smith {325), had fallen to 11,898,136 pounds, with a value of
$1,364,721; in other words, during this comparatively short interval, the supply was
practically cut in two, but the value greatly enhanced.

The lobster fisheries of Canada, which next to those of the codfish and salmon are
most valuable to the Dominion, have yielded, from 1869 to 1906, inclusive, a period
of thirty-seven years, a grand total of $83,291,553. In 1897 the produce of this fishery
was 23,721,554 pounds, valued at $3,485,265. Ten years later, in 1906, the yield had
dropped to 10,132,000 pounds, but, though less than one-half as great, it had nearly the

172

bulletin of the bureau of fisheries.

same estimated value, namely, $3,422,927. Notwithstanding the increased cost to the
consumer, even in Canada the total value of the fishery has begun to fall, the product
for 1906 being less by half a million dollars than that of 1905.

The lobster grounds of the Atlantic coast were the finest the world has ever pro-
duced. In Canada alone 100,000,000 lobsters have been captured in a single year. If
properly dealt with, it would seem as if this vast natural preserve should have yielded
lobsters in abundance and in fair size for generations and even centuries to come. But
instead, lean and still leaner years soon followed those of plenty, first in the older and
more accessible regions of the fishery, until the decline, which has been watched for
more than three decades, has extended to practically every part of this vast area.

The lobster fisheries of the old world, and especially the more important industries
of Norway and Great Britain, when they came to be pursued with the system and energy
characteristic of modern conditions, have experienced a similar decline, and upon the
whole attempts have been made to meet it in a similar way and with the same result.
The treatment has been of the symptomatic kind, and the real cause of the difficulty has
not been reached. Sweden, indeed, is said to have felt the need of protective measures
two hundred years ago, and to have framed the first laws regulating her lobster fishery
in 1686. In 1865 the export of lobsters from Norway, to England chiefly, reached
nearly 2,000,000 in numbers. Already as early as 1838 protective measures were being
vigorously discussed, and it was proposed to establish a gauge limit of 8 inches; but this
was rejected, and a close season (July 15 to September 30, and later extended from July
to November) adopted instead. From 1883 to 1887 about 1,000,000 lobsters were
captured on the Norwegian coast yearly, having a value of 640,000 francs ($128,000),
a large part of the product being consumed in the interior and the rest exported alive.
While this small fishery has maintained itself better than most others, it has suffered
still greater reduction in recent years.

The product and value of the lobster fisheries of Norway from 1815 to 1907 are given
by Boeck (24), and Appellof (505), the latter from official returns. According to these
data the best single year in its history was 1865, with a catch of 1,956,276 lobsters, and
the best periods from 1821 to 1830, with numbers ranging from 784,511 (1823) to
1,609,051 (1825), and i860 to 1886, with numbers varying from 987,370 (1877) to the
greatest record as given above. Since 1886 the annual catch has not touched the million
mark, and the numbers have varied from 549,446 (1892) to 992,761 (1907). It is further
interesting to note the steady rise in value of the produce of this fishery. Thus the catch
of 1883, namely, 1,255,790 lobsters, though greater than that of 1907 by 263,039, had
only about one-half its value, or 423,083 crowns ($114,232), as compared with 835,002
crowns ($225,450). Expressed in another way the average price of lobsters had increased
from 28.50 crowns per 100 in 1878 to 92.41 crowns in 1905, or over 300 per cent.

Herbst (136) writing about 1790, thus speaks of the importance of the lobster fishery
Norway at that time:

In the Stavanger district this trade brings every year more than 10,000 Reichsthaler into the country.
Yet many maintain that it is detrimental to Norway, since owing to the extensive fishing of lobsters, other
fish have left the Norwegian coast . . . The inhabitants of Zirlcson, Holland, were the first to under-

NATURAL HISTORY OF AMERICAN LOBSTER.

173

take this trade, and through it they have become very rich. Up to the present time also the English have
brought many lobsters from Hittland. From 30 to 40 lobster vessels come each year from Amsterdam
and London to Norway, and each carries from 10,000 to 12,000 lobsters . . . When a load is safely
landed it is very profitable, since a lobster which is bought in Norway for 2 Danish shillings is sold in
England for a crown. This is the fixed price for a lobster, 8 inches or over in length, the legalized
gauge. If a lobster lacks a claw, it is then sold for only a shilling . . . The females are considered the
best eating.

The lobster fisheries of Denmark, Holland, Belgium, France, Portugal, and Spain are
relatively of minor importance at the present time, and in most cases wholly insufficient
to supply the home markets. Roche, in 1898 (257) placed the total annual value of the
French fisheries of the lobster and langouste at 3,114,317 francs ($622,863), of which
1,425,572 francs ($285,114) was represented by the lobster ( Homarus gammarus ).

The yield of the lobster fisheries in the British Islands has in some years reached
a total of 3,000,000 lobsters, and complaints of a diminishing supply have been loud
and frequent. This would be a little over a third more than the returns of the Massa-
chusetts fishery in 1888, with its higher gauge of \o}4 inches at that time. Prince
maintains that lobsters are so dear in England that only one person in 1 5 has one to eat
in the course of the year. (See p. 368 footnote.)

Restrictive measures of some sort have been in force in England for a long period.
Thus, R. Brookes in “The Art of Angling,”® under “necessary cautions,” is careful to
state that “Eobsters must not be sold under Eight Inches from the Peak of the Nose
to the End of the Middle Fin of the Tail; the Forfeiture is One Shilling for each Lobster.”
He remarks that “Lobsters are taken in Pots as they are call’d, made of Wicker-Work,”
baited and set in 6 to 10 fathoms of water, or deeper, and adds: “Their Flesh is sweet,
restorative and very innocent.”

A review of the measures which have been taken to propagate the lobster and to
check the decrease in its fishery in recent times is given in chapter xii.

THE CAPTURE, TRANSPORTATION, AND ACCLIMATIZATION OF THE LOBSTER.

The principle of the modern lobster trap is that of the old-fashined rat trap
adapted for taking an aquatic animal with as keen a scent as the rodent, but with far
duller wits. The device is undoubtedly of great antiquity, but as modified and applied
for the lobster it is apparently not over 200 years old. It was introduced to this country
from Europe, where, as Boeck (24) plausibly suggests, it was first applied in this way
by the Dutch in 1713, and was adapted from the eelpot then in use.

Primitively lobsters were speared, gaffed, or hooked, and for a long time on the
coast of Norway were taken with wooden tongs about 12 feet long and adapted for use
in shallow water only; lobster tongs had not wholly disappeared at the middle of the
nineteenth century. All animals taken by such means were injured more or less severely
and were unfit for transportation. The gaffing of lobsters from small boats was a com-
mon practice in the early history of the American fishery, and a fisherman in Maine once

a 2d edition, London, 1740.

174

BULLETIN OF THE BUREAU OF FISHERIES.

told me that in the period of plenty, from 1855 to i860, he had taken 150 in this way
in a single morning.

Then followed the hoop net or bag, sometimes called “plumpers” in England, or
“Fallenkorbe” (basket traps) in Germany, which were in extensive use at the middle
of the eighteenth and locally to the middle of the nineteenth century, or even later.
This was a simple iron hoop with bag net attached and often with crossed and arched
half hoops over its mouth. When baited and sunk it had to be watched and pulled at
frequent intervals in order to secure the lobsters before they could crawl out. About
the year 1858 a giant male lobster, said to have weighed from 25 to 30 pounds, was
taken in one of these hoop nets in Golden Cove, Vinal Haven, Me.

Travis (264) describes the use of hoops at Scarborough, England, in 1768, but
Pennant a few years later remarked that lobsters were sometimes —

taken by the hand , Sut in greater quantity in pots, a sort of trap formed of twigs and baited with garbage ;
they are formed like a wire mousetrap, so when the lobster enters there is no return. They are fastened
to a cord sunk in the sea, and the place marked by a buoy.

This English lobster trap undoubtedly came, as Boeck suggests, from the Norwegian
“Tejner, ” or baskets, which were the Dutch adaptation of the eelpot, the Scandinavian
name being derived from “tun,” the long tough roots of the juniper tree ( 24 ). After
1713 they were made of plaited willow twigs. Linnaeus saw similar baskets in 1746
in use on the coast of Bohuslan. Herbst ( 136 ), writing in 1790, says that lobsters were
then caught in “Tuner,” “Teiner,” or lobster baskets (“Hummertienen” or “Hummer-
korbe”) made of birch twigs.

The tines in later use among the fiords of the Norwegian coast were sometimes
made of slats or rods nailed to small hoops, and at considerable intervals, which were
filled in with interwoven cords of hemp. There were entrance funnels at either end, a
door at the top, and a flat stone lashed to the bottom for weight, wThile in the center of
the trap was suspended a peg for attaching the bait. (See 309, p. 733.) When a lobster
was taken from the tine, his claws were securely bound with pack thread, and thus held
until he was delivered to the submerged box or car to await final transportation to
market.

Essentially this old-style trap has been retained in Europe, where it is to be seen
at the present day. Those examined at St. Andrews, Scotland, where they are called
“lobster creels,” in July, 1896, were small cylinders, made of a wooden frame covered
with netting, and were anchored by means of a flat stone tied to the bottom. A fisher-
man with whom I conversed on the beach had 40 of these creels, and was going to haul
them at 5 o’clock that evening, but with no expectation of taking any lobsters, for,
as he expressed it, the sea was too calm; rough weather brought better luck. The
“tiner” of the Helgoland fishermen, according to Ehrenbaum ( 84 ), are birdcagelike,
cylindrical or four sided, with the bottom weighted with stones, covered with netting
or wirework, and with funnel-shaped ends, like eelpots. Each is sunk to the bottom
with attached cord which is floated with corks. In Norway hemispherical wicker
traps, with funnel at the top, were occasionally used.

NATURAL HISTORY OF AMERICAN LOBSTER.

175

The American lobster trap of the present time is simply a larger and more efficient
modification of the old wicker “basket,” but made of laths with netted heads or ends
in the form of a funnel with entrance ring. On the outer islands and coast of Maine
the half-cylinder form is preferred. They are 2)4 to 4 feet long, 2 feet wide, and 18
inches high, the smaller sizes being now commonly used. A trap of this type which
I measured on Great Duck Island in 1902 was 3 feet 9 inches in length and 25 inches in
both height and width. The frame was of scantling, from which were sprung three
arches or “bows” of spruce, and to these were nailed laths at intervals of 2 inches, one
side being provided with a hinged door. The “heads” are made of netted cotton, or,
preferably, of manila cord, tarred and strung to a “funnel bow” or entrance ring of
spruce, 6 inches in diameter, and often, as in this case, set obliquely to the long axis
of the trap, the whole head being drawn inward to form an upwardly directed funnel.
The lobster, in order to get to the bait, must therefore climb up the funnel and pass
through the entrance ring; when once a prisoner it is liable to crawl over the ring
rather than through it to liberty. The spindle for holding the bait is an iron spike
securely attached to the center of the floor. Flat stones or bricks are used as weights,
and the trap is secured to a 6-strand manila warp, which serves to lower and raise it,
as well as to mark its position. This cord, the length of which is determined by the
depth of the water, is fastened by one end to a corner of the frame or “sill” of the trap
and by the other to a wooden float or buoy, which bears the owner’s color or mark.
Traps are commonly set on single warps, but in summer are sometimes strung to an
anchored ground line or trawl, to the number of 8 to 25 or more units and at intervals
of about 30 feet, according to the depth, so that when one trap is hauled to the boat
the next in line will be at the bottom. In this case the position of the anchor at either
end of the trawl is marked by a buoy. Trawls were sometimes set across currents
so that fine particles coming from the bait would be widely diffused, but the practice has
been mostly given up. Fishermen tend from 50 to 125 traps, according to conditions,
and some have two sets, the winter relay being left on the beach to dry out in summer.
The “counters,” or lobsters of legal size, are temporarily stored in floating cars until
gathered up by well boats, which carry them to the large markets or to the numerous
pounds along the coast, where they are stocked for the winter and summer trade.

The traps are baited with small herring, halibut, hake, or codfish heads or with
fresh or salted fish of any kind. The fishermen try to follow the movements of the
lobsters and in summer fish closer to the shores, ordinarily in from 1 to 10 fathoms,
but in winter they often go out 5 or 6 miles and set their traps in 20 to 50 fathoms of
water. The traps are pulled as often as possible, once or twice daily in summer, but in
winter weather a week or even a fortnight may elapse before the traps can be visited,
and many are destroyed by storms.

The fish commission of Massachusetts, in recommending the adoption of a double
legal gauge for lobsters of 9 to 1 1 inches, inclusive, proposed a standard trap which
should have an entrance ring not to exceed 3^2 inches, with slats not less than i)4 inches

bulletin of the bureau of FISHERIES.

176

apart, to work automatically to the extent of not permitting lobsters above legal size to
enter and of allowing the undersized to escape.

Lobsters destined for inland markets are successfully transported with or without
plugging the claws, packed in wet seaweed, and with ice at the bottom. For a long time
nearly the entire product of the Norwegian lobster fishery (see p. 172) has been sold in
England, the animals, usually with claws bound with cord, being carefully packed in
small fish boxes, in heather wet with sea water, and in summer with ice at the bottom;
care is taken not only to shield them from the drip, for they can not stand fresh water,
but also by means of paper linings to protect them from excessive cold; always with
the precaution of leaving suitable openings at top and bottom to allow the air to enter
and the water to pass out.

Early in the nineteenth century, according to Prince (219), several barrels of lobsters
were sent from Nova Scotia, as a present to King George III of England. Again in 1862
several tubs of lobsters in sea water were forwarded from the coast of Maine to the
Emperor Napoleon III of France. The longest sea journey yet made by the living
lobster was accomplished some time previous to 1896, when the Otago Acclimatization
Society of New Zealand succeeded in transplanting 9 lobsters from England, 3 only
having died on a voyage of 54 days, covering a distance of 12,000 miles through the
Tropics, where water not artificially cooled reaches a temperature of 84° F. The experi-
ment was repeated in 1906, and up to May 30, 1909, four shipments had been made
from Plymouth, England, to Portobello (Dunedin), for the fish hatchery and biological
station there. The last of these proved most successful, 31 out of 34 lobsters being
delivered alive. Each of the animals was given a separate compartment in the wooden
shipping tank, and was supplied with clean, well-aerated and cooled water, and \yas fed
during the voyage.

From 1874 to 1889 five attempts to acclimatize the American lobster on the Pacific
coast were made by the United States Fish Commission, when 590 animals of both sexes,
and some with external eggs, were successfully transported across the continent and
distributed at different points from Monterey Bay to Puget Sound. Accounts of these
early experiments have been given by Perrin ( 319 ), Rathbun (228) , and Smith (253, a).

No positive results having appeared [says Dr. Smith], the experiment was renewed in the fall of 1906,
when a special carload of brood lobsters, numbering more than all the previous plants combined, was
dispatched to Puget Sound, and in 1907 a still more extensive plant, aggregating about 1,000 adult
lobsters, was made in the same water. Further consignments will be made until the lobster is removed
from the list of failures and recorded as a great financial as well as a gastronomic success (325, p. 1406).

We believe that the Bureau has taken a most commendable step, and in the right
direction, the initial attempt being to find a water where the Atlantic lobster will
thrive. When this primary question has been settled, further importations to that
point, supplemented in time by artificial propagation, promise well for the eventual
establishment of new and remote fisheries which, for all that is now known to the con-
trary, may at some future da)^ enjoy a greater prosperity even than those nearer home.

NATURAL HISTORY OF AMERICAN LOBSTER.

177

HABITS AND INSTINCTS OF THE ADULT LOBSTER.

At this point we shall examine certain facts in the general natural history of the
lobster, leaving, however, such important subjects as reproduction, growth, and
development for special consideration.

The sea bottom is the natural abode of the lobster, as it is of all the large and
heavy Crustacea, the source of its food and the scene of all its activities, from the
close of free pelagic life to old age. Its external world is the ocean floor, to which it
reacts, and it knows no other. While its powers of locomotion are considerable, it
never forsakes the water of its own accord or leaves the bottom, to which nature has
consigned it by giving it a heavy body and a sedentary disposition. Lobsters wander
close to the shore and out to depths of over a hundred fathoms, and the nature of the
bottom, or more directly the supply of food, as well as the physiological condition of
the animals, especially in respect to their molting periods, determine their abundance
within these limits in any locality.

The supply of food, the temperature of the water, and in general the physical
conditions of the environment vary greatly throughout the range of this animal, as one
might infer from a study of the coast line. From Labrador to Maine the coast is very
rugged, deeply indented with bays, and studded with islands, some of which present
perpendicular walls to the sea. The coast of Maine, particularly in its eastern and
middle sections, is essentially bold, rocky, and diversified to an extraordinary degree
by deep channels, extensive bays, and inlets of all kinds, and these are studded with
rock-ribbed, spruce-clad islands. The geological formation is pre-Cambrian, the rocks
being mainly granites. From 10 to 30 miles from the shore we find large and important
islands standing alone or closely related, as Monhegan Island and the Vinal Haven and
Matinicus groups. All are essentially masses of granite, which in some cases have been cut
by glacial forces into archipelagoes; they abound in basins and channels of various
kinds, into which fresh sea water is driven with every tide, and thus form admirable
breeding grounds for food fishes, the lobster, and a host of invertebrates. The Cape
Cod region is distinguished for its extensive sand shoals, which resemble those of North
Carolina. The northern part of the Massachusetts shore is rocky, while the southerly
portions are very diversified, abounding in submerged ledges, sandy and weedy bottoms,
a great variety of bays and channels, as in Vineyard Sound and neighboring waters.
Here lobsters were once exceedingly abundant, until they were nearly exterminated
by the fishermen.

Under the variety of conditions indicated we should expect not only to find lobsters
larger and more abundant in some localities than elsewhere, a condition greatly influenced
by the number and persistence of the fishermen, but also to meet with variations in
the time of egg laying and hatching, of molting, and in the rate of growth.

This animal spends most of its time in the search for food and in reproducing its
kind. Its instincts are constantly leading it to secure protection through concealment,
and we find it burrowing in the mud or sand, or hiding under stones, whether to await
its prey or to pass in greater security the crises of its successive molts.

48299° — Bull. 29 — 11 12

1 78

BULLETIN OF THE BUREAU OF FISHERIES.

In traveling over the bottom in search of prey the lobster walks nimbly upon the
tips of its slender legs, which are provided with brushes of sensitive hairs. The large
claws are directed forward, a position which offers the least resistance to the water, or
when at rest are held somewhat obliquely, their tips touching the bottom, while the
long sensitive “feelers,” or antennae, sweep back and forth continually to give warning
of a foe or of objects which its other sense organs fail to detect. In exploring its feeding
grounds the movement of the body is chiefly maintained by the swimmerets, or pleopods,
wrhich spring from beneath the tail in the form of a double bank of paddles on either
side. The swimmeret consists of a short stalk and two flexible blades, which beat
rythmically writh a backward stroke, and thus impel the animal forward even without
the aid of the ambulatory legs. Each blade is further garnished with a fringe of long
and strong hairs or setae, which add to its efficiency as a rowing organ, and certain of
which in the female catch and hold the egg glue by which her progeny, in the form of
thousands of eggs, are tethered to her body.

The most primitive sense of animals being that of touch, it is not surprising to find
tactile organs widely distributed over the body of this crustacean. As will be seen
later, they occur by thousands in the form of tufts and fringes of hair-like setae on the
legs and free margins of the shell, and in any part subject to frequent contact either
with the body itself, with its food, or the ocean floor. It will also appear that instead
of being incased in a solid, impenetrable armor, the crustacean can receive stimuli and
impressions from without as readily as if it possessed a soft and delicate skin.

When an enemy appears, or the lobster is suddenly surprised and cornered, it will
immediately strike an attitude of defense. Raising itself on the tips of its walking
legs, it lifts its powerful claws over its head, after the manner of a boxer, and, striking
the offending object, endeavors to crush and tear it to pieces.

When transferred from sea to land the lobster can only crawl in its vain attempts
to walk, owing to the great weight of its body, which the slender legs are unable to
sustain. If turned on its back its discomfort is immediately shown by attempts to
right itself, which are usually successful. When taken directly from the water and
left to its own devices on the beach, I have seen it strike out by the nearest path to the
sea with as keen a sense of direction as a turtle shows on land. It should be stated,
however, that this experiment was tried only within short distances from the water.

By far the most powerful organ of locomotion in the lobster is its “tail,” called
also the “abdomen” (terms borrowed from vertebrate anatomy), and the “pleon.”
By the rapid flexion of this muscular tail, aided by its terminal fan, the lobster shoots
backward through the water with astonishing rapidity, going, according to one observer,
25 feet in less than a second. If tossed into the water, the animal quickly rights itself,
and with one or two vigorous flexions of the tail makes quickly for the bottom as if
sliding down an inclined plane.

On calm summer evenings toward sundown lobsters are often seen close to shore,
lying on little patches of sand or in eel grass, awaiting their chance to seize a passing
fish or crab. When alarmed, they assume the defensive attitude; but press them close,

NATURAL HISTORY OF AMERICAN LOBSTER.

179

or try to pin them down with an oar, and they will dart backward toward deeper water;
if still pursued they flee in other directions, zigzagging their way over the bottom until
safety is found at still greater depths.

Lobsters kept in aquaria of sufficient size and provided with running water often
thrive, and if they receive proper care will live for a long period. If the tank is pro-
vided with a pile of stones, the lobster will examine this carefully until the most attrac-
tive holes are discovered. When several individuals are placed in the same aquarium,
each soon selects a hole or corner, for the possession of which it is always ready to fight.
This is true of the “lobsterlings” as well as the adults, showing that the power of asso-
ciation or of the formation of habits, which is the mark of intelligence, is well developed.
When the occupants of the same aquarium are of equal size and show no weakness, they
usually live in peace; but should one become disabled, as by the loss of a claw, it is
quickly attacked by the strong and forthwith destroyed.

As the lobster lies in its corner of the aquarium, usually with the tail folded, and
always so if a female in “berry,” it slowly sweeps the water with its long, sensitive
antennae, which are now held erect, now lowered, until they lie horizontal and extend
directly forward in front of the body. The smaller antennae are elevated, while the
stouter outer branch of each beats with a rythmical up-and-down movement; this
branch carries the delicate hairs or setae, which are regarded as the organs of smell.
One often sees the animal deliberately lower the whip-like branches of the first pair of
antennae and clean them by drawing them through the brushes of the large maxillipeds;
the great claws when not extended and ready for immediate use are turned obliquely
inward and downward, with their tips touching the bottom.

All animals that play the part of scavengers must have strong powers of scent or
keen eyes to guide them to their prey, and lobsters are no exception to this rule. The
turkey buzzard sees, but, according to Audubon and Bachman, can not scent its prey,
while the lobster, though dull of sight, has a keen chemical or “olf acton7” sense. This
is illustrated by the way in which it can be enticed into the traps. It is asserted that
when traps are set on a trawl placed across the tide, the catch is greater than when the
trawl is set in the direction of the current, since in the former case the chemical sub-
stances, or fine particles coming from the bait, are more widely diffused. Lobsters are
sometimes wary and shy of entering a trap, and have been seen to crawl about it several
times and examine it cautiously on all sides before, too weak or too hungry to resist
temptation, they finally enter. When the pots are hauled, lobsters sometimes escape
by darting backward through the narrow opening of one of the funnels, but this seldom
happens and may be set down to accident.

Sluggish as the lobster may appear when out of the water and partially exhausted,
it is quite a different animal, as we have just seen, when free to move at will in its
natural abode on the bottom of the sea. In the water it is agile, wary, pugnacious,
capable of defending itself against enemies often larger and more powerful than itself,
and on occasion of exhibiting a high degree of speed. It often captures its prey by
stealth and with concealed weapons. Lying hidden in a bunch of seaweeds, in a rock

i8o

BULLETIN OF THE BUREAU OF FISHERIES.

crevice, or in its burrow in the mud, it waits until the victim is within reach of its
claws. Though far less active and keen witted than many of the higher crabs, and
sedentary in the sense of being restricted in its range, it is sluggish only at the period
of the molt or in very cold weather. The sense of hearing is probably absent and that
of sight far from acute, but this animal possesses a keen sense of touch and smell, possibly
a sense of taste, and is quite sensitive to changes of temperature and light (see p. 184).

MIGRATORY INSTINCTS.

Adult lobsters never migrate up and down the coast at definite periods or in con-
siderable numbers in any degree comparable to the semiannual movements of many
fishes and birds; in April and May, however, they come in toward the shore, and again
in fall retire to deeper water. Such migratory instincts as they possess are of a very
diffuse type and are far from being generally displayed. The abundance of food and
periodic necessity of molting and laying eggs, and the temperature of the water, may
one and all enter with more or less force into bringing about local and restricted move-
ments. When the question of food is paramount, lobsters will pass the winter in con-
siderable numbers in the shallow waters of harbors, but usually only on a rocky bottom
where food is to be found. The extent of their journeys is influenced by the slope of
the bottom and the depth of water, as well as by the nature of the bottom itself, and
varies in different sections of the coast as well as at the same point in different seasons.

Movements of tagged lobsters. — In order to test the extent and rapidity of the adult
lobster’s movements along the coast, as well as to and from deep water, some interesting
experiments in tagging lobsters have been made by Bumpus {43) at Woods Hole, Mass.,
Mead and Williams (295) at Wickford, R. I., and by Meek (316) and Appellof ( 303 ) in
Europe.

In the summer of 1898 Bumpus tagged 479 lobsters from which eggs had been
removed, and liberated them at various points about Woods Hole. Seventy-six of
these were recaptured and the tags returned for identification. The valuable data thus
obtained showed a great variation in the “migratory” impulse and remarkable rapidity
of movement in individual cases. Some had not strayed far after gaining their freedom
for from 3 to 4 weeks, being recaptured near the points where they had been set free,
while others had moved at the daily rate of a mile for a period of 10 to 12 days. One
of them which had been freed at Woods Hole on July 2 entered a trap at Cuttyhunk
Island, 12 miles to the southwest, on July 13, having covered this distance in 11 days.
It does not seem probable that such sporadic movements are determined by the search
for more abundant food, or for more favorable conditions as regards the temperature
and depth of the water or character of the bottom, but are to be set down to individual
initiative and general restlessness of behavior. In this connection it would be interest-
ing to learn whether the more sedentary or the more active individuals had showed
any evidences of preparation for the molt, which is due in female lobsters shortly
after the hatching of the eggs (middle May to middle July at Woods Hole).

Tagging experiments were undertaken by Mead in the summer of 1902 and 1903
at Wickford. Of the 16 released in the first season, the most enterprising traveler had

NATURAL HISTORY OF AMERICAN LOBSTER.

181

covered io miles in less than 8 days. Out of 385 lobsters tagged and set free in 1903,
30 were later reported, most of them having taken a southerly or southwesterly course
down the Narraganset Bay. Eight which had been free from 9 to 31 days had
traveled only a mile when captured, June 11 to July 3; 6 had wandered from 10 to
12 miles in the course of 22 to 58 days, having been liberated June 24 to July 26.
Further systematic experiments in this interesting subject have been carried on at the
Wickford station, and are recorded by Barnes (75 and 16, a). One of the fastest trav-
elers made 4 miles in a single day.

Movements off Cape Cod and at Woods Hole. — If there were any considerable coast-
wise migration, it is evident that regions once depleted could be restored under favoring
conditions by accessions from neighboring parts. Apparently this does not occur, and,
as Rathbun has observed, we may regard each geographical section of the coast as
inhabited by a more or less distinct colony, which tends to hold its ground fairly con-
stantly, so that if its numbers be once seriously depleted, recovery under nature must
needs be a slow process at best. The history of the Provincetown region on Cape
Cod, already referred to, seems to support this idea.

The region about Woods Hole, Mass., including the western end of Vineyard Sound,
No Man’s Land, and the Elizabeth Islands, was studied for a period of 5 years, from
1890 to 1894, with reference to the general natural history of the lobster, and the follow-
ing conclusions were then reached regarding its migratory habits: The general move-
ment of lobsters toward the shore in the spring is modified by reason of females with
old eggs finding it advantageous to remain on rocky ledges until their young are hatched,
while the males press onward to shallower water. After hatching is over, the females
make their appearance in large numbers in the sound toward the last of June or 1st
of July, and form a large part of what fishermen call “school lobsters” or “buckle
shells.” Their appearance is probably not as sudden as it often seems. Fishermen
as a rule work only one set of traps, setting them now here, now there. In order to
follow the movements of these animals systematically, it would be necessary to set
traps simultaneously in different places and on different bottoms, and to record the
catch for a considerable time.

Some females with old eggs come into the sound before the young are hatched, but
the majority do not. It must also be borne in mind that many lobsters remain in the
sound and harbors the year round, and that these observations refer only to the move-
ments of the larger number. Toward the latter part of August the pendulum begins to
swing the other way, and the lobsters move into deeper water or to a rocky bottom.
This outbound movement is continued during the months of September and October,
but, as already remarked, it is by no means general and may be more pronounced in
cold than in mild seasons.

Aside from their in and off shore movements, the lobsters must be regarded as
essentially sedentary or stationary animals. Yet their occasional sudden appearance
in great numbers, and often at points where a previous scarcity had been noted, creeping
toward the shores in veritable swarms of thousands of individuals, as already reported
by Sars (244), Appellof (305), and myself (149, p. 21), indicate that at certain times and

182

BULLETIN OF THE BUREAU OF FISHERIES.

under certain conditions not at present completely understood, movements of a somewhat
different character may take place. The “traveling lobsters” of Sars probably belong
to this category, and my former suggestion that they might represent “some large
species of surface-feeding shrimp” (149, p. 19), may be an error, as Appellof asserts.
Sars’s account, if correctly translated, is somewhat ambiguous; it is as follows: “The
hard-shell and ponderous lobster must always make an extra exertion in moving about,
and its movements can therefore not be of long duration. People certainly talk of
the ‘traveling lobsters’ (‘Faerd-hummer’) which are said to come from the open sea
in large schools, and some even say that they have seen such schools many miles from
the coasts moving about rapidly near the surface of the sea. If this is really so, I con-
sider it as absolutely certain that these schools come from no very great distance, possibly
from some of the elevated bottoms off the coast.” (No. 244, p. 675.) We consider it
highly probable that the “swarms” referred to represent only more concentrated move-
ments of the usual inshore character, the animals coming from elevated areas not hitherto
discovered and fished.

In general we conclude that since lobsters as a rule spawn in warming water the
migratory impulse must be regarded as primarily correlated with the development of the
reproductive organs, which periodically respond to a rising temperature. Incidentally
the carriage of eggs, the abundance of food, and molting which occurs in the female
shortly after the eggs are hatched, tend to disturb the regularity of these movements.

OPTIMUM TEMPERATURE.

While the question of food supply must be of paramount importance to all bottom-
feeding animals like the lobster, the temperature of the water can hardly fail to exert
some influence upon their movements. Whether there is a direct reflex response in
the lobster to the warming waters of the shores in spring or not, it is a fact that it shows
a marked tendency, as we have seen, to move shoreward at this time. Further, without
any doubt, there is a certain optimum temperature, under the influence of which, when
other conditions are favorable, growth is most rapid, and those dependent processes of
reproduction and exuviation most accelerated. The data available, however, do not
enable us to determine this point with much accuracy.

The physical conditions of Woods Hole region have been made the subject of
special study by Sumner,® from whose account the following facts have been gathered.
The temperature of sea water at Woods Hole for May ranges from 50° to 6o° F. The
warmest period extends from approximately July 12 to August 24 (which corresponds
with the height of the spawning period of the lobster at this point), with a temperature
of 70° to 710. The September range of 69° to 65° is about the same as that for the first
half of July. In the latter part of October the water cools to about the same tempera-
ture it had reached during the first half of May. The lowest daily temperature, of about
30°,is recorded for mid-February. The bottom temperature at the western end of Vine-
yard Sound, at the period of maximum summer heat, was found by Sumner to be 60.2°,

a Sumner, Francis B. An intensive study of the fauna and flora of a restricted area of sea bottom. Proceedings of the
Fourth International Fishery Congress, Bulletin of the Bureau of Fisheries, voL xxvm, p. 1223-1264. Washington, 1910.

NATURAL HISTORY OF AMERICAN LOBSTER.

183

or about io° lower than the average at Woods Hole at a corresponding period. A station
in that part of the sound which showed in August a bottom temperature of 550 (60.3°
at surface) gave in March 36.7° (at the surface 37. 40).

The temperature of the surface water of Winter Quarter Shoal, Virginia, ranges
from 350 to 76° F. ; at Five Fathom Bank, New Jersey, the range is 370 to 76°. Dela-
ware Breakwater, which at one time was practically the southern limit of the lobster,
is situated between the lightships anchored upon these two shoals. In the Gulf of
Maine the mean annual range is approximately 320 to 62°, while at some points the
maximum is only 540. (228.)

The average temperature on the north shore of Prince Edward Island has been given
as 56.56° in June, 63.40° in July, and 62.27° in August, the bottom temperature in
6 to 8 fathoms being estimated at 55°.

The temperature of the sea on the Labrador coast is said not to exceed 46.05° F.
on the warmest summer days. The lobster thus seems to be debarred from this coast
east of the straits of Belle Isle by the Arctic current and the lingering ice.

From the facts given above we may infer that the optimum temperature of the
lobster lies between 50° and 60° F. When the temperature of the sea water marks
from 50° to 55° in spring large numbers of these animals have already begun to creep
nearer the shores into shallower and warmer places, and again in fall, when the tempera-
ture has fallen to this point, many have already been impelled to recede to greater
depths. Many lobsters, however, remain in the relatively shallow water of harbors all
winter, a fact already emphasized; so it is certain that temperature is not the only
influence at work in directing these semiannual movements. The question of food
or nature of the bottom may at times be of equal or of even greater importance.

The lobster, like many other marine invertebrates, is very sensitive to the extremes of
heat and cold. If exposed to direct sunlight out of the water, or to the nipping air of a
winter’s day, it weakens or succumbs in a short time. On the other hand, if packed in
seaweed with ice it will live for days or weeks, a fact daily illustrated in the transporta-
tion of this crustacean alive to inland markets far from the coast. (See p. 176.)

Lobsters which pass the winter in relatively shallow water often seek protection
by burrowing in the mud, as usually happens when they are confined in pounds. In
such cases a long period of severe cold may prove fatal. On March 10, 1882, a number
of lobsters were taken through the ice by the scoop of a mud-digging machine off the
coast of Prince Edward Island. They were said to be sluggish but not torpid.

INFLUENCE OF LIGHT AND NOCTURNAL HABITS.

The lobster is essentially an animal of the twilight, and in its semiadult and adult
condition explores the bottom in quest of food mainly after sundown or at night, when
it is generally far more active than by day. This may be proved by anyone who
watches its behavior when confined in either lobster cars or pounds. These animals
it is true on occasion move about by day, but at night they become exceptionally rest-
less. It is probable that the eggs are laid and that pairing takes place as a rule under

184

BULLETIN OF THE BUREAU OF FISHERIES.

the cover of darkness, either at night or in early morning. Such indeed is known to be
the common habit of crayfish, shrimp, and many other Crustacea.

While the lobster is very sensitive to light throughout every stage of its existence,
its reactions to this stimulus are of a complex character, especially during its free swim-
ming career, as will be seen in a later chapter. It will appear that the young shun or
avoid light of a greater intensity or move toward or away from a source of light and in
the direction of its incident rays as a result of the varying state of the animal itself and
of its environment. There seems to be ever a struggle among competing impulses, now
one set of reactions winning the day, now another. In general the young seem to seek
the light, as their swimming habits might lead us to expect, and are usually captured in
the day time, but they are sometimes caught at night.

After the discovery of the bottom has been made, through all their later adolescent
and adult stages they practice concealment, and prefer the twilight of their rock caves or
tangles of weed amid the sand. Yet, under exceptional conditions, the adult may
expose itself to stronger light.

According to Forel, light can not penetrate the ocean below a depth of 400 meters
of tolerably clear water, but even in fifty fathoms off the Atlantic coast the difference
between day and night can not be very considerable. This is not the case in shallow
bays or sounds with sandy bottoms, which lobsters frequent in summer, and where
we may expect to find the greatest difference between their diurnal and nocturnal habits.

The large floating cars in which lobsters are generally stored in readiness for market
are always kept closed. When they are particularly shallow and the lobsters are exposed
to the glare of the sun they are sure to suffer, and sometimes die in consequence. The
majority of lobsters probably spend the greater part of the year at depths where the
effect of sunlight is but slight, and during the course of its evolution the eye of this
animal has become sensitive to a minimum quantity of light. For this reason alone we
should expect that adults would tend to avoid intense sunlight.

BURROWING HABITS.

The lobster not only digs up the sea bottom in its search for shellfish and covers itself
with mud in cold weather, but burrows under some conditions as extensively as the
muskrat. Impounded lobsters will sometimes burrow during both summer and winter,
and this habit is no doubt freely practiced when they roam at will.

The burrowing habit was typically shown in one of the pounds at Southport, Me.,
where the lobster holes were driven horizontally into a mud bank for a distance of from
1 to 5 feet. When we did not see the feelers and claws of a lobster projecting from its
hole, the occupant could usually be felt by inserting the end of an oar, and it would
sometimes grip the blade and allow itself to be dragged out clear.

The holes had an opening of from 8 to 10 inches in diameter, which allowed of
their being readily probed and measured with an oar blade. I did not observe that
they ever had an upward or downward curve, but they sometimes swerved to the
right or left, which might be due to the presence of some obstacle in the path. In

NATURAL, HISTORY OF AMERICAN LOBSTER.

185

some cases the burrows were under rocks, and the entrance was often much larger than
that described, possibly owing to the union of the mouths of two originally distinct
burrows. The pile of dirt and the broken clam shells which are sometimes seen near
the hole of the lobster recall the excavations of the muskrat. It was exceptional to
see a lobster with his tail projecting from the burrow, and when disturbed in this posi-
tion they were quick in disappearing.

In digging, lobsters probably make use of their large claws and walking legs, and
possibly the tail fan may be brought into service as a scoop or shovel, but we have no
observation in support of the latter supposition. Yet, in some cases we have noticed
the underside of the tail fan to be scratched and scarified, and the marginal fringe of
hairs worn down in a way to suggest the probability of such use.

Mead (193) found that the young lobster sometimes burrows in its fourth or
lobsterling stage, and this instinct is very pronounced in all its later phases. It removes
bits of gravel presumably with its claws and deposits them short distances away, thus
digging to a depth of 2 or 3 inches. Young lobsters, like the old ones, hide in their
holes, and issue stealthily in search of prey. Indeed, it may be said that such com-
manding instincts of the adult as preying, concealment, and fear, are manifested sud-
denly and for the first time in the fourth stage.

The burrowing habits of certain species of crayfish are well known, while those
of the stomatopods (see chap. 1) are equally characteristic. We meet with the
same habit in many snapping shrimps, expressed in a greater or less degree in terrestrial
crabs, and in a great number of the lower Crustacea.

FOOD AND PREYING HABITS.

The food of the adult lobster consists principally of fish, alive or dead, and of
invertebrates which inhabit the bottom and come within its reach. It is not unusual
to find bits of algae or common eel grass in its stomach, and at times in such quantities
as to suggest that it may not be an accidental occurrence. Vegetable matter, however,
forms at most but a small and casual part of its diet. Fragments of dead shells, coarse
sand, and gravel stones as large as duck shot are also swallowed. The former yield
lime, which is in some measure absorbed; the latter are not needed in grinding the food
as in the gizzard of the domestic fowl, since the lobster’s stomach has, as is well known,
a mill admirably adapted for this purpose, and their occurrence is probably accidental.

I have dissected soft lobsters, with fragile papery shells, from 3^2 to inches long,
in which the stomach was literally crammed with water-worn calcareous fragments
of the dead shells of crustaceans and mollusks such as one can gather on the beach,
besides other shells of mollusks which had undoubtedly been eaten alive. This sug-
gested the possibility that the supply of lime for hardening the new shell might at
times be obtained in this way (see 149; p. 89-90) for it seemed hardly probable that
they would be swallowed to be immediately regurgitated. The lobster undoubtedly
regurgitates the insoluble and indigestible parts of its food, as is the known habit of
crayfish. Some such outlet for waste matter is absolutely necessary in an animal

i86

bulletin of the bureau of fisheries.

where the fluid or finely divided and digestible parts of the food only can pass to the
delicate intestine. The hard parts of fish, mollusks, and crustaceans, however, appear to
be retained until they have given up a good deal of their lime, thus contributing to the
calcareous supply of the exoskeleton.

An analysis of the stomach contents of lobsters captured at Woods Hole from
December to June revealed the following organisms, which are named in the order of
their relative abundance : Fish (procured independently of the traps) ; crustaceans,
embracing chiefly isopods and decapods; mollusks, consisting largely of small uni-
valves; algae, echinoderms, and hydroids. The bones of the fish eaten belonged as a
rule to small individuals or species. Among the crustacean remains parts of small
mud-crabs, Panopceus ( P . sayi and P. depressus, the common species in Vineyard
Sound), were almost invariably recognized, and it was not unusual to find parts of the
skeletons of small lobsters. The isopod Civolana concharum is frequently eaten by
the lobster, and often in large numbers. It is a scavenger, and devours the bait used
in the traps, a fact which explains its common occurrence in the stomachs of lobsters
newly caught. In the case of a female, captured in January, the stomach was filled
with fresh lobster eggs in an advanced stage of development. These eggs were not
stolen from any lobsters in the trap, but under what circumstances they were obtained
one can easily conjecture. The egg-lobster is undoubtedly a shining mark, not only
for predaceous fishes but even for members of its own species. The larger mollusks
are eaten by crushing the shells and picking out the soft parts, while many of the
smaller kinds are swallowed entire, and presumably pulverized in the gastric mill.
Echinoderms probably enter largely into the diet of the lobster wherever they abound.
Parts of the common starfish ( Asterias forbesn) and rarely a few spines of the sea
urchin ( Arbacia punctidata) were detected, but it might be that the latter were swal-
lowed together with other calcareous fragments. Very little change in the food was
noticed during the winter and spring months, and there was little evidence that the
appetites of these animals sensibly abated during cold weather, yet it is probable that
food if not less abundant is less necessary in winter.

That lobsters catch fish alive there is no doubt, but few observers have ever seen
the feat performed. Fish that inhabit the bottom, like the flounder, would naturally
fall an easy prey to the powerful claws of the lobster, which is said to catch the sculpin;
and I have known a lobster when confined in an aquarium to seize and devour a sea
robin ( Prionotus evolans).

While lobsters are great scavengers, it is probable that they always prefer fresh
food to stale. Some fishermen maintain that there is no better bait than fresh
herring. Fresh codfish heads, flatfish, sculpins, sea robins, menhaden, and haddock
are also used, as well as salted fish. The flesh of sharks was occasionally used by the
Gay Head fishermen on account of its firmness and lasting qualities. Nothing could
be more offensive to the human nostril than the netted balls of slack-salted, semi-
decomposed herring, which are commonly used as bait on the coast and islands of
Maine, but by the wonderful chemical processes which are continually going on in the

NATURAL HISTORY OF AMERICAN LOBSTER. 1 87

laboratory of its body, the lobster is able to transmute such products of organic decay
into the most delicate and palatable flesh.

Lobsters are very fond of clams, as they are of mollusks of all kinds, and when
kept in pounds are constantly scoring and digging up the bottom in search for these
shellfish. In a large lobster pound at the Vinal Haven Islands I have seen the
muddy bottom scored in all directions, the work of lobsters in their search for clams.
One was reminded of a pasture in which the soil had been rooted up by pigs. As a
fisherman remarked, if you put lobsters in a pound and do not feed them they will
soon turn over the bottom as effectively as it could be done with a plow. Some of the
holes which the lobsters had made in digging clams were 2 feet in diameter and 6 inches
or more in depth. Here they had dug up the eel grass, or loosened it so that it had
floated to the surface, and cartloads had been cast ashore. We have already seen
that the lobsters sometimes eat parts of this plant, but they had plainly rooted it up
in this case with another object in view. The broken and often comminuted shells of
the long-necked clam ( Mya arenaria ) could be seen strewn everywhere about their
excavations.

The lobster probably attacks such large and powerful mollusks as the conchs,
which live upon hard bottom in deep water, and devours their soft parts. An illus-
tration of this was afforded in an aquarium at Woods Hole in the summer of 1892,
when a conch ( Sycotypus canaliculatus) was placed in the same tank with a female
lobster which was nearly 10 inches long and which had been in captivity about eight
weeks. The conch, which was of the average size, was not molested for several days,
but at last, when hard pressed by hunger, the lobster attacked it, broke off its shell,
piece by piece, and made quick work of the soft meat.

If a lobster that has fasted for a number of hours is fed with a little fresh meat,
such as a piece of clam or fish, the process of feeding will be found to be one of no little
interest. The lobster eagerly seizes a piece of food with the chelae of the third and
fourth pairs of walking legs, and passes it up to the third pair of maxillipeds, which
are held close together, each being bent at the fifth joint and folded on itself. With
the third maxillipeds thus pressing against the mouth, the food is kept in contact with
the other mouth parts, all of which are in motion, and their action is thus brought to
bear upon it. By means of the cutting spines of the appendages external to the man-
dibles— chiefly the maxillae and second pairs of maxillipeds — the meat is as finely divided
as in a sausage machine, and a stream of fine particles is passed on toward the mouth,
to be finally subjected to the cutting and crushing action of the mandibles before
entering it.

If one wishes to watch the movements of the complicated mouth parts more
closely, one has only to take a lobster out of the water, place the animal upon its back,
and when it has become sufficiently quiet stimulate the mandibles or the broad plates
of the second pair of maxillipeds with the juice of a clam or the vapor of ammonia,
which can be squirted with a pipette. Masticatory movements are immediately set up
in the appendages, those belonging to the side stimulated usually working independ-

i88

BULLETIN OF THE BUREAU OF FISHERIES.

ently. The two small chelate legs are also drawn up rapidly to the mouth, as if to
hand up pieces of food.

When stimulated in this way, the plates of the first pair of maxillae come together
over the lower posterior half of the mandibles. The movements of the masticatory
parts of the second maxillae are synchronous with the beating of the scaphognathite.
These leaf-like plates project somewhat obliquely over the convex surfaces of the jaws,
and are directed inward and slightly upward. The large plates of the first maxillipeds
work up and down and at the same time inward toward the middle line, describing an
ellipse. The second pair of maxillipeds move alternately or together, inward and out-
ward, with slight up-and-down movement. The large maxillipeds move together, the
toothed margins meeting like the jaws of a nutcracker, while the three terminal joints
are bent inward and somewhat downward, as in the case of the second maxillipeds,
so as to meet on the middle line below and hold the food up to the mouth. (For full
analysis of the mouth parts, see ch. vi, p. 227.)

CANNIBALISM.

Lobsters are cannibals from birth, owing, primarily, to their strong instinct of
pugnacity. The small, as well as the large, are ever ready to prey upon those still
smaller or weaker than themselves. This is certainly true of all the lobsters which have
been kept under observation in the restricted space of hatching jars or aquaria and
where suitable food in suspension was either lacking or insufficient. In their natural
environment in the sea, however, where the young are quickly and widely dispersed,
opportunities for the display of this tendency could seldom arise. In the early stages,
at least, it is questionable whether cannibalism would occur under any conditions,
provided the larvse were properly fed.

When crowded in cars or pounds, lobsters play the role of cannibals at a great rate.
As Mr. F. W. Collins remarked to me in 1902, persons not understanding this will lose
20 per cent of their stock in a very few days. He usually counted on a loss in crowded
cars of 5 per cent in the course of three days, the larger feasting on the smaller, even
when the precautions of supplying them with food and separating the “soft shells”
had been duly taken.

REVIEW OF THE INSTINCTS AND INTELLIGENCE OF THE ADULT LOBSTER.

The instincts of fear and of concealment by burrowing or hiding in seaweed or
under stones; the restless activity of the lobster in exploring the bottom for food, feel-
ing its course by whipping the water with its long antennae, and testing all objects
with both these and its sensitive feet, or smelling its way to food by beating its anten-
nules, even seeming at times to stalk and approach its prey by stealth; storing up food
or, at least, dragging dead prey into its burrows or sometimes burying it, to be after-
wards exhumed, thus recalling a well-known trait of the dog; the fighting instinct so
often displayed between members of its own race and not confined to captives, which
brings into play all its caution and characteristic attitudes in attack and defense; its

NATURAL, HISTORY OF AMERICAN ROBSTER.

189

incessant activity at night whether in search of prey or not; its irregular migratory
movements to secure, it may be, a rocky bottom where food and better places of con-
cealment abound, deeper or warmer water, or, in a word, those conditions which for
the time suit better certain individuals of one or the other sex for feeding, spawning,
or shedding the shell — these may all be observed in either free or captive animals.

In every movement the lobster is guided chiefly by the chemical sense and that of
touch, and, least of all, by its eyes. Thus vision, which is never keen, is probably
almost nil in bright lights. This explains its nocturnal activity and its frequent retreat
from light to shadow.

Of the habits of the European lobster, Williamson (282) remarks that it has the
sense of light and shade, that it will test a strong shadow with its antennae, and will
even jump at it with outstretched and snapping claws. It is guided mainly by its
antennae, with them finding and exploring every cavern, and with them searching its
depths before entering or inserting a claw. As I shall point out elsewhere, the wary
lobster, “tiptoeing” over the bottom, feels its way at every step. If food is thrown
to the captive, no appeal is made to its sense of sight. The bait remains unnoticed
unless it happens to touch one of the antennae or legs; but a lively whipping of the anten-
nules seems to announce the awakening of the chemical sense. The lobster immediately
takes notice and begins to explore the water with its long “feelers,” at first without
leaving its hole. The antennules begin to whip in the direction of the food and explora-
tions become more active. The lobster cautiously leaves its hole, goes straight for the
bait, feeling its way. The food is usually picked up and handed to the mouth parts by
the second pair of legs.

Meanwhile, says Williamson, the expected feast has by association stimulated the maxillipeds,
which are actively working as if they were already masticating the food. Once this is seized it is con-
veyed to the maxillipeds and the lobster retreats to its hole, there to enjoy its meal. Two lobsters were
noticed to have stored up in one case some mussels and in the other a dead sand eel ( Ammodytes
tobianus) in the inner recesses of their caves.

In regard to the interesting question of storing food, we give the account of a
lobster which was kept at the Rothsay aquarium in England (302):

A flounder was unintentionally left in one of the aquaria, in which three lobsters were living. The
largest animal immediately appropriated the fish, which was then dead, and buried it beneath a heap
of shingle, over which it mounted guard. Five times within 2 hours was the fish unearthed, and as
often did the lobster shovel the gravel over it with his huge claws, each time ascending the pile and
turning his bold defensive front to his companions.

To this catalogue of instincts we must add the parental instinct of the mother
lobster in protecting her cargo of eggs during the long period of fosterage. The paren-
tal instincts of birds are, as a rule, far keener than in the invertebrates; but it should
be added that in many of our commonest birds they endure for a time which is only
an eighth or a tenth as long. Through her inbred caution the mother lobster saves
not only herself but her progeny from many a strong and clever adversary. Barring
the fisherman’s trap, she will run the gauntlet of daily life, escape a thousand perils,

BULLETIN OF THE BUREAU OF FISHERIES.

190

and after 330 days or more of successful fosterage deliver her young to the teeming
and merciless sea. She shows this parental instinct not only by keeping to cover but
by folding her tail in emergencies, so that the inquisitive cunner and insidious eel and
other troublesome neighbors can not pick off her eggs or pull them out of her brood
pocket. Further, by the incessant beating of the egg-laden swimmerets, the lodgment of
destructive parasites is discouraged. The lobster also instinctively cleans her antennae
by drawing their whips through the brushes of the great maxillipeds and applies the
“broom,” the tips of the last pair of slender legs, to the swimmerets and underside of
the tail when ready to deposit a new batch of eggs.® Sexual union is largely, if not
wholly, indiscriminate, and it is possible that the males “try” every lobster which they
meet, or at least every female, whatever her condition (see p. 303).

Lobsters about to molt, and possibly after the shell is cast, often conceal themselves
in sand or seaweed, and the soft lobster will instinctively eat its own cast or swallow a
miscellaneous mass of calcareous fragments, presumably for the purpose of obtaining an
immediate and abundant supply of lime for the hardening of its new shell (see p. 185).

Most important to the welfare of the lobster race no doubt is the instinct of fear
upon which all their characteristic actions of burrowing, hiding, and what we have
described as “stealth” and “caution” depend. Moreover, it is as important for the
life of the young as of the adult, for this instinct manifests itself with comparative
suddenness, as in birds, at the close of the larval swimming life, in the fourth-stage
lobster, when, as if by magic, the lobsterling casts aside its larval habits, together with
its characteristic larval organs, and appears in a new role, with new armor to suit the
part which it is to play. It betrays fear and caution, and now goes to the bottom, digs
burrows, and hides. The possession of the instinct of fear gives ground for the hope
that the method of rearing the }mung to the fourth or fifth stage before liberation,
which has met with complete success, may yet furnish a means of restocking our coastal
waters, and of thus reviving the decayed lobster fisheries of the northern Atlantic States.

The intelligence of the lobster is shown in its power of associating things with
actions or of forming habits in the technical sense; in other words, in a power, however
limited, of profiting by experience. Thus the lobster habitually returns to its burrow
or place of hiding, which it recognizes and claims as its own, being ready to fight for its
possession. There can be little doubt that it finds its way back by the same process that
the fox returns to its hole or the bird to its nest, through the power of association, though
not necessarily through the mediation of the same sense.

But this rudimentary power of using experience as guide does not carry the lobster
very far any more than it does many of the fishes and lower vertebrates generally. It
does not enable it to escape from a trap or to avoid this engine of destruction in the
future when once set free.

a it may be noted further that Coste, who made some remarkable statements about the European lobster which are not
confirmed by later observers, says that “In order to favor incubation the brood lobsters can expose at will their eggs to the
light or keep them in shadow, according as they bend or straighten their tails; when assuming the latter attitude they will
now bring their eggs to rest, or now wash them by gently moving the swimmerets.” (55, p. 204.)

NATURAL HISTORY OF AMERICAN LOBSTER.

191

COLOR IN THE ADULT LOBSTER.

The color of the adult lobster is due primarily to the presence of pigments, either in
a state of solution in the blood or in the form of granules in the protoplasm of certain
cells, particularly the chromatoblasts, which lie beneath the euticular epithelium. The
chromatoblasts are richly supplied with blood, which flows in a system of irregular
9inuses through the spongy tissues underlying the epidermis.

In the adult lobster the hard shell is an opaque lifeless substance, and the pigments
to which it owes its characteristic coloring are excreted by the chromatoblasts of the
soft underlying skin. These are immediately exposed upon removing the shell. The
delicate skin is seen to be flecked or mottled with scarlet, and with the aid of a simple
magnifying glass it is readily perceived that its color is due to branching pigment cells,
groups of which correspond to the blotches of color on the shell itself. The excreted
pigments undergo physical and possibly chemical changes in the hard euticular shell
and may thus come to differ markedly in color from the parent chromatoblasts. Since
the colors of the lobster reside in a lifeless body, the pigment layer of the shell, it is
evident that no changes of a vital nature can take place after this is definitely formed.

The coloration of the lobster is fairly uniform in plan, but extremely variable in
details, even more so than we find in the case of the color patterns of many insects.
The brilliancy and purity of the shell pigments depend largely upon the age of the shell
or upon its condition with respect to the molting period. These pigments are usually
most brilliant just after the molt, when the cuticle is thin and translucent, and dullest
before eedysis begins, when the old shell still encumbers the body.

The pigment cells themselves, as we have seen, reside in the soft skin, and when
the shell is once hardened the color of the animal is more or less fixed and permanent.
It is certain, however, that under the action of light and possibly from other natural
causes the shell pigments undergo molecular or chemical changes. Men who handle
lobsters have frequently observed that when they are exposed in shallow cars to unusually
intense light they become decidedly bluer in color.

According to MacMunn {185) the coloring of the skin of the lobster is due to the
presence of chromogens, which may be converted on slight provocation, as by dehy-
dration, oxidation, or some molecular change, into a red lipochrome resembling rhodo-
phan. Everyone is familiar with the wonderful change in color which the living lobster
undergoes when boiled, and according to the same writer the beautiful pigment of the
larval lobster is converted by alcohol into a true lipochrome.

Alcohol quickly converts the chromogens in the lobster’s shell into lipochromes
and dissolves them at the same time. This is seen when a recently molted lobster with
brilliant coloring is placed in alcohol for preservation. The soft shell is first reddened,
and then in a short time completely bleached, while a hard lobster treated in the same
way will retain much of its shell pigment for years, if not indefinitely.

Lipochromogens are found in a natural state in the gastric glands, blood, soft skin
(as the blue prismatic cyano-crystals, which are reddened by alcohol or by boiling),

192

BULLETIN OF THE BUREAU OF FISHERIES.

and in the exoskeletons of crustaceans generally. MacMunn is of the opinion that they
are “built up in the digestive gland and carried in the blood current to be deposited in
other parts of the body.” If this is true, it would not be remarkable if the color of the
animal were affected by the nature of its food, yet this does not seem to be often the case.

Following the classification of Bateson (79) we distinguish between (a) variations
in colors themselves, and ( b ) variations in color patterns. The variation in colors,
which Bateson calls “substantive variations,” may be the result of a physical or chemical
change, and has no vital significance. The different colors themselves are further
liable to different discontinuous variations, as when crustaceans occasionally lay bright,
golden-yellow eggs, while the normal color is dark green.

The following substantive variations have been met with: (1) Blue lobsters, in
which the prevailing color is blue; (2) red lobsters, which are pure red or reddish yellow;
(3) cream-colored lobsters, characterized by the almost entire absence of color; and we
should also add (4) black lobsters, to include possible cases of melanism, where the
colors are extremely dark. A specimen of this kind was reported to me at Beal Island,
near West Jonesport, Me., where a fisherman recently captured, in 3 fathoms of water
among the eelgrass, a lobster about 6 or 7 inches long with moderately hard shell and
almost jet black. He supposed at first that it was covered with coal tar. It did not
appear to be preparing to molt. Malard speaks of meeting with cases of melanism in
crabs, where in consequence of a lesion of the skin the animal becomes entirely black.

Changes in color pattern are more elusive. There are (1) the normal variety, in
which the upper part of the body is mottled with green, blue, and cream color; (2) spotted
or “calico” lobsters, the coloration of which is a bold pattern of green and light-yellowish
or cream-colored spots; (3) pied or parti-colored varieties, in which the contrast of
tints is abnormally pronounced. This may perhaps be better classed under substantive
variation. The changes are due apparently to vital or physiological causes, which have
at least no adaptational significance.®

There is no sexual color variation in the lobster, and such substantive variations
as the eggs undergo are not of an adaptive character. The freshly laid egg is dark green,
sometimes almost black, due to the presence of dissolved lipochromogens. Occasionally
the ova are nearly pea-green, grayish-green, or greenish-straw color, but the golden-
yellow variation, so striking in some of the snapping shrimps, has never been observed
in the lobster.

If the eggs are treated with hot water, alcohol, or other killing reagents, the green
lipochromogen is quickly converted into red lipochrome. When the water is heated
gradually, the red color appears slowly, and it is interesting to observe that if these
red eggs are now plunged into cold water the green color is restored. This change may
be somewhat analogous to the breaking up and reconstruction of the blue compound of
of starch and iodine upon the successive application of heat and cold, and to the varia-
tion in color which sometimes appears in the living animal at the time of the molt.

a For fuller account of red living lobsters and other color variations, with illustrations, see 14Q.

NATURAL HISTORY OF AMERICAN LOBSTER. 193

Soon after the water has been brought to the boiling point the red color becomes
permanent.

The colors of deep-sea animals that live in total obscurity can not be of any utility
to the animal as a source of protection. The color may be very brilliant, red, scarlet,
orange, rose color, purple, violet, and blue, which is less frequently reported, but they appear
to be developed quite independently of the light. It has been shown by experiment
with sensitive photographic plates that luminous rays do not penetrate ordinary sea water
to a greater depth than 400 meters, as noted above. In depths of 50 fathoms or more
there might be an appreciable amount of light on clear days, but even then, when the water
was loaded with sediment and the bottom composed of dark materials, it seems hardly
probable that colors would have any protective value whatever.

The normal colors of the lobster, which are spread like a mantle over the whole
upper surface, tend undoubtedly to obliterate it and to screen its movements while
crawling over a weedy or rocky bottom. The absence of all color or a more generous
display of bright pigment would make it a more conspicuous object, especially upon
sandy bottoms in shallow water, which it is usually careful to avoid in the daytime.
The vivid red of the claws appears to be overlaid by a darker pigment in spots, particu-
larly on the upper surface. The underside of the pleon, which rests upon the bottom
when the tail is not folded, is very meagerly supplied with pigment, as is usually the case
with marine animals which inhabit the bottom.

48299° — Bull. 29 — 11 13

Chapter III.— GIANT LOBSTERS.

Stories of gigantic lobsters made their appearance at a very early period, and one
could probably gather as many exaggerated accounts of this animal now as in the days
of Olaus Magnus. Time, however, has narrowed the bounds of credulity, even among
the ignorant, and we no longer hear some of the interesting legends which the old writers
have carefully handed down. Thus Olaus Magnus tells us in his description of northern
lands and seas,a published in 1555, that between the Orkneys and Hebrides there lived
lobsters so huge that they could catch a strong swimmer and squeeze him to death in
their claws. His curious figures were copied by Gesner, who has many others equal to
any which are described in the old mythologies.

Giants are met with in all the higher groups of animals. They interest us not only
on account of their actual size, but also in showing to what degree individuals may
surpass the mean average of the race. It may be a question whether lobsters weighing
from 20 to 30 pounds or more are to be regarded as giants in the technical sense, or
simply as sound and vigorous individuals on whose side fortune has always fought in
the struggle for life. I am inclined to the latter view, and look upon the mammoth
lobster simply as a favorite of nature, who is larger than his fellows because he is their
senior; good luck never deserted him until he was stranded on the beach or became
entangled in some fisherman’s gear.

Gesner gives a poor likeness of a lobster, but an excellent drawing of the large
crusher claw of one which he had preserved in his collection on account of its great
size. The length of this claw was inches, and its breadth at the junction of the
dactyl about 4 inches, so that it was borne by a lobster which weighed not far from 8
pounds.

The European lobster of to-day seldom or never attains so great size as the American
species, as already remarked, and its average weight is considerably less. Buckland
gives an account of large lobsters from the British Islands, in which the greatest weight
recorded was 14 pounds, and European lobsters of this size are undoubtedly now very
rare. The Academy of Natural Sciences of Philadelphia possesses a skeleton of Homarus
gammarusb which, judging from its measurements, must have weighed from 23 to 25

a Historia de Gentibus Septentrionalibus, Rome. 1555.

b It is possible that a mistake has been made in attributing the Philadelphia specimen to the European species The deter-
mination was made by Prof. John R. Ryder, who evidently relied upon the character of the rostrum (see p. 161) in basing his opin-
ion. Regarding this specimen, Professor Ryder wrote under date of March io, 1894, as follows: “It turns out to be European
instead of American. I send the data obtainable. The catalogue does not give weight or locality. At one time there was a
label stating the weight; now that has also disappeared.’’ Again on March 15, he wrote: “There is no doubt of the large lobster
being H. vulgaris. I found no spines on the under side of the rostrum of the large specimen; perfectly smooth, as was also another
smaller specimen of the same species. I mad 2 a very careful examination to-day and can assure you that the facts are as I state.”
He further added that the large skeleton “is also perfectly symmetrical and must have been a beautiful specimen originally, as
it now is.”

194

NATURAL HISTORY OF AMERICAN LOBSTER.

195

pounds. (Table 1, no. 15.) There may also be seen in the museum of Bergen, Norway,
a lobster which Prof. S. 0. Sars in 1878 described as an “immense specimen,” the living
weight of which could not have been much over 12 pounds.

Though it has been an accepted belief that the American lobster attains a greater
size than its European counterpart, it is possible, in view of comparison of no. 10 and
no. 16 of table x, that the maximum size of each species is nearly the same. The data
are not at hand for determining the question with certainty. It seems certain, however,
that American lobsters of average or medium size are considerably stockier and have
larger claws than the European, and that length for length, such animals will weigh
more. The lobster fishery of Europe, though pursued for ages by primitive methods,
is still very much older than that of America, and it is probable that the larger
lobsters have been more effectually weeded out there than here. At the time Sars’s
paper was written (244) it would not have occurred to one familiar with the American
species to speak of a 10 or 12 pound lobster as in any way remarkable, yet at present
few of this size find their way to our markets. In fact the same gradual falling off,
due evidently to the same cause, has been experienced for many years in Maine and
Canada.

Table; i. — Record of Giant Lobsters.

[No. 1-14 refer to Homarus americanus. No. 15-16 to H. gammarus .]

Crushing claw.

Toothed claw.

No.

Sex.

Place of capture.

Date.

Length.

Length of

Where preserved.

Living

weight.

carapace.

Length

Girth.

j Length

Girth.

Inches.

Pounds.

Gloucester, Mass.

1840

17-50

Peabody Academy of
Science, Salem, Mass.

a 28

1850

1868

21-75
20. 25

9.94

9-37

12. 50
12. 50

15-25

12.37

13-25

a 23-25

a 24

Boothbav, Me. . .

11. 12

Land Office, Booth-

bay Harbor, Me.

12.50
i 3- 12

15- 50
16. 12

® 24

a 25

12. 87

8. so

tion, Washington.

1891

20+1

9+1

13-75

16.87

13-87

12. 50

A d e 1 b er t College,
Cleveland, Ohio.

628

1892

20. 62

9* 25

11.50

Campobello Island,
New Brunswick.

a 23

1894

20-21

12-13

Formerly at St. Nicho-
las Hotel, Boston,

a 23-25

Mass.

Atlantic High-

1897

23- 75

12. 24

20. 50

I5- 50

15-25

American Museum of

lands, N. J.

Natural History,

New York.

Newport, R. I.c .

19.50

n-75

11.87

mission Inland Fish-
eries, Providence,
R. I.

Atlantic High-

1899

22.50

10. 28

14. 66

17- 68

14.40

13-54

American Museum of

lands, N. J.

Natural History,

New York.

1899

23-24

032+

land, Me.d

19. 80

12.33

15. 60

12. 40

a 24

Natural History,

New York.

Near Bayonne,

1898

20.37

13-50

11. 50

a 25-28

N. J.

9. 29

Museum of University
of Pennsylvania,

19-40

13. 10

16. 80

12. 40

10. 15

a 23-25

Coast of Norway.

i85o(?)

Philadelphia.

18. 73

8. 58

10. 23

10. 62

10. 03

8. 07

Bergen Museum, Nor-

O I2-J-

way.

0 Living weight estimated, b Living weight estimated from weight when boiled. c After Hadley, d Body length eti mated.

196

bulletin of the bureau of fisheries.

The large Belfast lobster (no. 6, table 1), which came into my possession in 1893,
was captured in Penobscot Bay, near Belfast, Me., in 1891. (For full account with photo-
graphs see 149.) Its total length, had the rostrum been perfect, would have been 21
inches. The body seems surprisingly short for so powerful an animal, and it is indeed
in the large claws that the greater part of the weight and strength resides. This may
possibly be explained by the fact that as age advances the increase in length at each
molt becomes less, while there is a corresponding gain in the volume of the body and
of the claws. Thus Ehrenbaum mentions a lobster 42.2 cm. long, which showed an
increase in length of scarcely 1 mm. on molting. The length of the crushing claw of
the Belfast giant is 13.75 inches, and its greatest girth 16.87 inches.

GREATEST SIZE ATTAINED BY THE LOBSTER.

It is difficult to obtain exact data regarding the true weights and measurements
of all big animals, and the lobster seems to be particularly deceitful in this respect.
Remembering the decision of the judge that “affidavits are not lobsters,” I endeavored
to take a conservative position on this subject, when writing in 1895 (see 149, chap-
ter v). Fortunately since that time two specimens of the mammoth class have been
added to the collections of the American Museum of Natural History in New York.
Through the kind offices of the museum I have been able to obtain data and to present
a sketch of one of the biggest known lobsters in the world. The larger (no. 9, table
1), when received in the fresh state, weighed, according to Whitfield (278), “about 34
pounds;” the weight of the smaller (no. 11 of table) is given as “about 31 pounds.”
Both were taken alive by fishermen off the Atlantic Highlands in New Jersey in
the spring of 1897. The larger animal was exhibited in one of the tanks at the Cas-
tle Garden Aquarium, but neither lived more than a few days in captivity. Both
specimens have been remounted at the museum, the smaller to show the upper (fig. 1)
and the larger the under side.

The most important measurements upon which we can rely for exact comparisons
are: (1) The length of the carapace from the tip of rostrum to hinder border, (2) the
length of each of the big claws, taken with callipers from the short spur near the proximal
end of the larger division of the claw to its apex,® and (3) the greatest girth of the
propodus, measured in a line at right angles to the last. These values should be fairly
constant by whomsoever made, and in whatever form the skeleton is mounted.

Knowing the measurements in the American Museum specimens to be correct,
and assuming that the weights as given by Whitfield are correct also, I have taken
these data as a new basis for estimating the weights of other large lobsters recorded
in table 1, and believe them to be a closer approximation to the facts in each case than
I was able to make in 1895. The former estimates were founded on the measurements
and supposed weight of the Belfast lobster (no. 6, table 1), the largest specimen known
at the time. I was assured that this animal weighed 23 pounds after it had been boiled,
and allowing a shrinkage of 40 per cent in the process, its living weight was estimated
at 28 pounds. Notwithstanding the doubts cast upon this statement at the time, com-

a Or from the spur near the proximal articulation to apex of propodus, the last measurement being somewhat less. Where
big claws are chopped off for preservation, the joint is apt to be defective.

37"

NATURAL HISTORY OF AMERICAN LOBSTER.

197

•$;

Fig. i. — Giant lobster from New Jersey; living weight, 31 pounds. (See table 1, no. 11.) Outline after photo-
graph, and reproduced through courtesy of the American Museum of Natural History, New York. General meas-
urements of skeleton as mounted, indicated in inches. About one-fifth natural size.

198

bulletin oe the bureau of fisheries.

parison with the measurements of lobsters 9 and n shows that it must have been sub-
stantially correct. It wTill be seen that this animal approaches closely the 31-pounder
from New Jersey, the lengths for the carapace being 10 inches (allowing for 1 inch of
the rostrum missing) and 10.28 inches, respectively, and the girth of the crusher claw
16.87, as opposed to 17.68 inches.

After taking account of the facts so far as ascertainable at present, my former state-
ments regarding the weights of giant lobsters are revised to the following effect; the
greatest known living weight of the American lobster is 34 pounds and that of the
European lobster about 25 pounds. (See note, p. 194.) Altogether six or seven individ-
uals of the American species weighing 25 pounds or more are known to have been
caught on the Atlantic coast during the last 70 years.

The lobster (no. 12, table 1) which was seen by Cobb at Peak Island, Maine, in
1899, is said to have measured 44 inches with claws extended in front of the head. It
was caught off Monhegan Island, Maine, and exhibited about the country by fishermen
of that region. If this measure was correct, it would correspond to a body length of
23 to 24 inches and a corresponding weight of upward of 32 pounds, thus being one of
the largest lobsters on record. The ratio of body length to the total length with extended
claws varies greatly in small and large lobsters, being as high as 72 per cent in a female
of 3 inches and 38 per cent in a male of 10.37 inches, while in the big Belfast lobster
(no. 6) this ratio is somewhat under 55 per cent. On the other hand the ratio of cara-
pace length to total body length for the average 10.5-inch lobster, as applied in the
gauge law adopted in Maine, is 45 per cent (see chapter iv, p. 212).

In addition to the lobsters given in table 1, Cobb (52) has noticed a male said to
have measured 25 inches and to have weighed 25 pounds. It was caught in a hake
trawl off the Matinicus light, Maine, at a depth of 60 fathoms, in 1898. The given length
in this case does not accord with the given weight, and is probably much too great.
Another lobster is mentioned by Hadley (126) as having a length of 22.5 inches, but
weighing only 19.5 pounds; the same kind of difficulty is presented here, the length
calling for a much heavier individual. Waite (274) has also recorded the measurements
of a large male lobster, which was captured at Block Island April 10, 1896, measured
21 inches and weighed when alive slightly over 22 pounds. The length and girth of
the cracker and toothed claws were 13.25 and 16.5 inches, and 12.75 and 12.25 inches,
respectively.

In June, 1898, Dr. H. M. Smith called my attention to a large lobster which had
been recently captured in New Jersey and which was reported to have measured 23
inches in total length and to have weighed 36.5 pounds. Through the kindly aid of the
late E. G. Blackford of the Fulton Market, New York, we were able to obtain a reliable
account of this interesting specimen, together with the necessary measurements, which
are given in table 1. This lobster was caught on June 21, 1898, by a fisherman in New
York Bay, off East Forty-sixth street, near Bayonne, N. J., and was taken alive to the
Bayswater Hotel, where it was on exhibition in a tank for several days. The man who
was sent by Mr. Blackford to take the required measurements found that the animal

NATURAL HISTORY OF AMERICAN LOBSTER.

199

was then dead and partly dried out, the owner claiming that it had shrunk 2.62 inches in
consequence. It is hardly necessary to show that this was impossible, since the body
of a lobster can be distended at only one point, namely, at the articulation of the carapace
and the tail, and there only to the limit of the articular membrane, which is inelastic.
Drying would tend rather to contract this membrane and to give more accurately the
true length, but the difference would not in any case be very great. The measurements
taken from the dead shell show that this animal probably did not weigh over 25 to 28
pounds. In his letter to Dr. Smith Mr. Blackford remarked that the owner asked the
modest sum of $250 for the specimen. We do not know what finally became of it.

In August, 1891, according to Mr. F. W. Collins, a lobster of undetermined sex was
caught at Blue Hill Falls, Maine, which weighed 18.5 pounds, and in November, 1892, a
perfect female lobster weighing 18 pounds was taken at Green Island, Maine. This
outer island has long been noted for its fine lobster fishing. Mr. Collins stated that in
August, 1891, he had 50 lobsters at one time in his establishment which would weigh
from 10 to 18.5 pounds. About half of these came from Castine and the remainder from
Blue Hill Falls. All of them were “new shell lobsters,” or those which had shed in the
year, probably in July.

After the lobster has attained a length of 20 inches and a corresponding weight of
23 to 25 pounds or more, we may be certain that the stage periods, or intervals between
each molt, are long, and probably several years apart, and that this interval is gradually
increased with advancing years. The relative increase in length seems to slow up with
increasing age, but volumetric increase still goes on, and the animal becomes stockier
and its big claws more powerful. There is no fixed limit to age, growth, or molting
power, but the practical limit is probably not far from that of the largest animal on
record. Whether giant or pigmy, the fighting strength is apparently renewed at each
molt, when a brand new suit of armor is acquired.

The shell of the crusher claw of the Salem lobster (for full-sized drawing, see 149,
pi. 15) weighed but a trifle over a pound, and the living weight of this animal is now
estimated at about 28 pounds. The skeleton of the crusher of a 12 to 15 pound
lobster with very dense shell weighed 8.25 ounces. The Salem lobster had probably
molted within less than 3 months from the time it was caught. The Lubec lobster
(no. 7) had a clean shell, which indicated that not over 6 months had intervened
between the time of its capture and the last molt. It was light for its length and
the most perfectly proportioned large specimen I have seen.

In general it is undoubtedly true that the older the adult lobster the longer its
stage periods and the less the increase at each molt. Yet it is almost equally certain
that both may vary greatly in the giant as in the pigmy. At present our data regarding
the molting of large lobsters is insufficient to enable us to estimate their age. Giants
weighing from 25 to 35 pounds have possibly weathered the storms of life for half a
century or more.

Chapter IV.— MOLTING.

Molting is an incident and expression of growth. The crustacean does not “grow
by molting,” as is sometimes said, but it molts because it has grown. It has outgrown
its inelastic shell, which is cast off in one piece, normally without a break in any of
its hard parts. Other animals molt or shed a part of their cuticle and its products, but
nowhere is the process so striking, so abrupt, or so critical as in the higher Crustacea.
In these animals the span of life from infancy to old age and death may be divided into
a series of stages, varying in length, each stage-period of life culminating in a molt.

Any influence which retards growth or unduly taxes the vital energies prolongs
this period, and conversely the more vigorous and the more rapid the growth the shorter
the interval between molts. Shortly after molting the body increases in size, probably
in part through the absorption of water, but this expansion should be distinguished
from the change that has already taken place, which is due to cellular growth, and is
the primary cause of the molt. Thus in molting the animal parts with its old shell or
epidermic exoskeleton at one stroke, and presently attains to greater size.

Molting begins on the second day after hatching and lasts throughout life or at
least as long as there is any growth. The first three molts are passed in from 12 to 15
days. From first to last the cuticle is cast as one piece (excepting only the gastro-
liths), the animal escaping through a rent of the membrane between the tail and back.
In healthy young animals molting lasts but a few minutes, but at all times the process
is critical and it is frequently fatal. It often leads to the distortion or the loss of limbs
and to a variety of deformities such as duplications of a limb or of its parts.

It is difficult to avoid repetition in dealing with the molting process since it has
modified the habits of the animal at so many points, but we shall now consider the
subject in regard to the adult animal as a whole. In order to understand the process
it will be necessary to examine the structure of the shell and of the soft skin, of which
the former is a product.

THE SKIN AND SHELL.

The skin as a whole is composed of the soft dermis, the soft epidermis, and the
shell or cuticle which the latter secretes. The epidermis is typically composed of a
single stratum of chitin-producing cells, and often rests upon a thin basement mem-
brane, which then forms a distinct boundary between the two layers and like the outer
shell is a cuticular product. The dermis is composed of connective tissue cells, which
are often attached to the basement membrane, blood vessels, nerve fibers, pigment
cells, and glands, which are apparently of epidermic origin. Wherever muscles are
attached to the shell, the epithelium is greatly modified or reduced (see ch. vi, p. 241).
The shell in sectional view shows four layers, namely, (1) a thin outermost stratum,
which is structureless, called the enamel layer; (2) an underlying and lamellated pigment

200

NATURAL HISTORY OF AMERICAN LOBSTER.

201

layer, transversed by vertical canaliculi, abounding in pigment and impregnated with
mineral s^lts; (3) the calcified layer proper, devoid of pigment, but otherwise like the
last, and forming the greater part of the shell substance; and (4) a nonealeified inner
stratum composed of very thin lamellae.

The chitinogenous epithelium may be compared to the Malpighian layer of the
epidermis of the vertebrate, while the layers of chitin represent its horny cuticle,
though formed in a different manner. The vertical canaliculi of certain decapods,
according to Vitzou (272) , correspond to the boundaries of the epidermic cells, but this
is not the case in the lobster, where they are close together and very numerous.

During the molting period the cells of the chitinogenous epithelium undergoes a
great change, its cells being extended vertically into very long and slender rods (pi. xlvi,
fig. 2). The epithelium developed over the surface of a budding limb is of a similar
character. The chitinous layers of the new shell are formed by discontinuous thicken-
ings of what, according to Vitzou, may be regarded as the upper wall of the epithelial
cell. Thus are formed parallel lamellae of varying density, which fuse with those of
adjoining cells and make a continuous shelly crust.

At the time the shell is ready to be cast the tegumentary coverings consist of (1)
the old shell, (2) the new shell, (3) an intermediate structureless membrane, besides
the chitinogenous epithelium, and (4) the dermis. The new carapace, according to
Vitzou, is composed of the enamel and pigment layers only. The calcified layer is
not formed until after the molt.

Certain peculiar cells which have been referred to as connective tissue become very
conspicuous at the molting period, particularly in the dermis, and experimental evidence
seems to show that they secrete glycogen which is used in the production of the new
shell, but no exact knowledge concerning these structures is available at present. The
enamel layer is the first formed, and when once laid down can not be removed except by
the shedding of the entire shell. However, it is worn away by abrasion, as seen in the
old hard-shelled animals, and its function is purely protective.

The surface of the shell has a punctate appearance, due to hair-pores, which
mark the points where hairs or seta; now pierce the shell or where they were present
at an earlier stage of development. In the adult lobster the seta of the carapace have
disappeared more or less completely except upon its margins and in the orbital region.

The dense shell of this animal is in reality a veritable strainer, being perforated
by hundreds of thousands of minute passages, which lead from the surface to the parts
below it — to the tegumental glands on the one hand or to the sensory cells which lie at
the roots of the hairs on the other.

PERIODS, CONDITIONS, AND SIGNIFICANCE OF MOLTING.

The hard-shell lobster is heaviest, has the firmest flesh, stands transportation best,
and is therefore most valuable for the market. A large percentage of all lobsters taken
during the fall and winter months are of this character, and nearly all lobsters caught
in March, April, and May belong also to this class. Shedders and soft-shell lobsters
are taken in greater or less abundance from June to October, varying somewhat with

202

BULLETIN OF THE BUREAU OP FISHERIES.

the season and surrounding conditions, such as the nature of the sea bottom and the
temperature of the water. By far the greater number of lobsters cast their shells during
the months of July, August, and September. The time of shedding, however, varies
considerably on different parts of the coast, being from 4 to 6 weeks earlier in some
seasons in western Maine than in the extreme eastern section. Shedders are not fit
for the market, being lean and watery, and soft lobsters are in a similar condition and
will not bear much handling or transportation. Until the shell becomes tolerably hard
the soft lobster is easily wounded and killed. Lobsters with very soft shells and those
that have been mutilated are often kept in the lobster preserves or pounds until the
shell is hardened or the injury repaired.

Traps set by Mr. Vinal Edwards at fixed points on the rocky bottom in the harbor
of Woods Hole, Mass., for a period of 7 months, from December 1, 1893, to June 30,
1894, were daily hauled and the conditions of the shell of each lobster noted. The
significant data thus obtained were as follows:

Table 2.— Data for Lobsters Examined at Woods Hole, Mass., with Reference to Molting

Condition.

Number of lobsters caught.

Lobsters
recently
molted or
preparing
to molt.

Shell
hard and
dull.

Shell soft.

Males 1, 313

Females 1,344

Total 2, 657

Of the entire catch, 110 lobsters had either recently molted or were preparing to
molt; 77 of these were males and 33 females. The total number of males was smaller,
yet the number of soft shells among them was nearly twice as great as in the other
sex. This fact implies that the males molt oftener than the females, which would be
an a priori deduction from the greater size which the male attains, or that they molt
more frequently during this period, assuming that the distribution of these animals
was uniform for the time and place.

In the fullest sense the molting process consists of two distinct phenomena: (1)
The formation of a new shell and (2) the rejection of the old. When once formed the
shell admits of no increase in size, since it is a dead structure, excreted by the soft
skin below it, and when it is outgrown it must be cast off and give way to a new and
larger covering. The new shell is gradually secreted under the old one, and when the
latter is discarded the new cuticle is soft and flexible, so that it is easily distended to
meet the requirements of growth. The growth of the lobster, as of every arthropod,
is thus measured by a series of stages characterized by the growth of a new shell under
the old, by the shedding of the outgrown old shell, a sudden expansion in size, and the
gradual hardening of the shell newly formed.

NATURAL HISTORY OF AMERICAN LOBSTER.

203

Not only is the external shell east off in the molt, along with the linings of the
masticatory stomach, the esophagus, and the intestine, but also the internal linkwork
of hard tendons described in chapter vi. The sloughing of the latter is rendered pos-
sible, first by the presence of absorption areas and secondly from the fact that the
inner skeleton is in origin an infolded part of the cuticle; in molting the lobster with-
draws its soft body from the mold of its old and hardened skeleton. It is thus easy
to see why the molting act is a continually recurring crisis in the life of the decapod
crustacean, for it is both dangerous and expensive, not only calling for a considerable
excess of energy, but demanding that a long series of preparatory changes, to be later
considered, must be exactly executed. Since it is dependent upon the condition of the
individual, which is subject to wide variation, the molt does not take place at any
stated time, but may occur in any month of the year. In general, molting in either sex
is rare in winter and spring and most frequent in summer. Warmer weather, a more
active life, a greater abundance of food, and a more vigorous appetite, which are char-
acteristic of the lobster or its environment during the warmest part of the year, are
most favorable to the renewal of the shell. The lobster, though a carnivorous animal,
feeds less in winter, when its habits are relatively sluggish. Broken limbs and injuries
to the shell are then but slowly repaired, and there is less energy to be drawn upon in
molting.

As a rule, the adult female that lays her eggs in August of any given year carries
them for 10 or 11 months, until they hatch in the succeeding June. Since the spawn-
ing periods are 2 years apart, Hadley (126) infers that the molting periods can not
oftener occur and that the rate of growth in the female is consequently diminished.
In average cases this rule may hold, but exceptions occur. Thus, I have recorded two
cases {149) where soft-shelled lobsters with eggs were taken in which the molt could
not have preceded ovulation by more than two or three weeks; still further, in excep-
tional cases, a second molt may possibly take place in late autumn or in the early
winter, following the hatching of a brood.

It is several weeks before the new envelope becomes as hard as the one rejected,
so that the lobster is, for a large part of its life, either preparing for a molt or recovering
from one. Therefore it is not remarkable that lobsters have acquired many popular names
among fishermen, such as “hard shell” or “old shell” lobster, “shedder,” black shell,”
or “crack shell” (lobster preparing to molt), “soft shell,” “new shell,” “shadow,”
“rubber shell,” “paper shell,” “buckle shell” lobsters, etc. (animals which have
recently molted).

Shedders can be readily distinguished by the dark, dull colors of the old shell,
hence the common name of “black lobster,” and by the deep reddish tint of the mem-
branes at the joints, where the flesh is seen through the old and new cuticulae. The
lobster is now naturally sluggish and takes but little food, but it can not be said that
the shedder never breaks its fast. It is not a very unusual experience for the fisherman
to take both the soft lobster and its cast from his traps. When in this condition
lobsters commonly haunt shallow water, with a sandy, muddy, or weedy bottom, and

204

BULLETIN OF THE BUREAU OF FISHERIES.

at low tide have been taken out of bunches of eelgrass at a depth of a few inches only.
They frequently dig a shallow hole in the mud under stones, where they can await the
coming change with greater security from enemies. Fishermen have frequently seen
a cast shell lying on the bottom and have found a soft lobster near by, protected by a
rock or bunch of kelp.

Many of the prawns habitually molt in the early morning while it is yet dark, but
lobsters which we have kept in aquaria have cast both by day and at night. Consid-
ering the nocturnal habits of the lobsters, we should expect to find the latter practice
the commoner in a state of nature. In those captives which Brook (57) observed with
great care, the shells were cast off in the night time and partially buried.

Anderton (5) found that the lobsters transported from England to New Zealand
molted mostly at night, their cast shells being usually seen lying upside down on the
bottom. The shedders retired to some secluded spot where the water was shallow, and
appeared vicious upon the approach of intruders. On the 3d of September, says
Anderton, “a male lobster was seen to be behaving in a very peculiar manner in the
shallow end of the pond. It would walk alongside the concrete dividing wall for a distance
of about 5 feet, halt, and then turning round would retrace its steps the same distance
in the opposite direction. In this manner a rut several inches deep was formed in the
gravel and at one end of this the lobster scooped out a hole about 4 inches deep and
12 inches in diameter.” The water had to be temporarily withdrawn from the pond,
but as soon as permitted to do so this lobster resumed its peculiar walk, and continued
it through the night and the following day. Molting began at 4.30 p. m. of that day
and lasted 35 minutes. The lobster at first lay on its side, with its large claws extended
in a direct line with its body, and later turned on its back when the tail, the last part
to be withdrawn, was released. The habit of scooping a hole in the gravel was noted
on several occasions, when the soft lobster was found lying beside its “shadow.” As
noted in chapter ix, molting in the females was almost immediately followed by copula-
tion, whenever a male was available, and the interval between this act and the laying
of the eggs was in two cases observed — 65 days. Molts in both sexes were recorded
from November 18 to March 3, but rather more frequently in the warm months of Novem-
ber and December.

THE MOLTING ACT.

A male “shedder” was caught in the harbor of Woods Hole July 13 and placed
in an aquarium. At exactly 2.48 p. m. this lobster began to molt and in 6 minutes
was out of its shell.

When the lobster is approaching the critical point the carapace or shell of the back
gapes away a quarter of an inch or more from the tail. Through the wide chink thus
formed the flesh can be seen glistening through the old and new cuticle, giving it a
decidedly pinkish tinge. Take the lobster up in the hand now and the tail drops down
as in death, the strong muscles which bind the pleon to the carapace being completely
relaxed. When this stage is reached the time of exuviation is at hand and the process
becomes purely automatic, the animal having no control over its own movements.

NATURAL HISTORY OF AMERICAN LOBSTER.

205

The period of uneasiness, which foreshadowed the molt and was very marked,
ended in this lobster by its rolling over on its side, briskly moving its legs, and bending
its body in the shape of the letter V, the angle of the V corresponding to the gaping
chink between the dorsal shield and tail. Presently the old cuticle, holding these parts
together, began to stretch, the wall of the body pressing against it with considerable
force, and the hinder end of the shield being slowly lifted up, while its anterior part
remained attached to the rest of the skeleton. The slow but sure pressure of the parts
within cause an increasing tension in the yielding cuticular membrane, which finally
bursts, revealing the brilliant colors of the new shell. The legs and other appendages
are occasionally moved, but no marked convulsive movements are to be seen. The
carapace has now become raised to an elevation of perhaps 2 inches in its hinder part,
in consequence of which, the anterior end being fixed, the rostrum is bent downward
and the animal presents a very singular appearance.

When this stage has been reached the lobster becomes quiet for a few seconds and
then resumes its task with renewed vigor. From this time on until free its muscles work
intermittently. The doubled-up fore part of the body, with each effort of the animal,
is more and more withdrawn from the old shell, and this implies the separation of the
skin from the intricate linkwork of the internal skeleton, and particularly in its release,
together with a part of the nerve cord, from the closed archway of this structure, as
well as the freeing of the 28 separate appendages from their old cases and tendons, for
the accomplishment of which special adjustments are made in advance. The cuticular
sheath of every ectodermic structure is stripped off. The exoskeleton folded to fit so
complicated a mold is virtually a continuous structure, and from the method of its
regeneration the sloughing of one part necessitates the shedding of the whole.

The carapace is now elevated to such an extent from behind that the rostrum is
directed obliquely downward and backward. The lobster is still lying in comparative
quiet upon its side, but the muscles of all its appendages are undergoing violent con-
traction as the animal tugs and wrestles violently as if to free itself from ropes which
bind it down firmly on every side. The carapace is unbroken, yet the two halves bend
as upon a hinge along the median line, where the lime of the shell has been absorbed.
Presently the pressed-down bases of the antennse, the eyestalks, and the bent-down
rostrum of the new shell can be clearly seen. No part of the covering of the large
claws or of any of the legs have been split or cracked. The muscular masses of the
powerful claws have been withdrawn through their narrow openings without a rent.
Finally a few kicks free the entire forward half of the body, the antennae, chelipeds,
and varous other parts, which now lie above or to one side of the old covering. The
tail has been gradually breaking away from its old case, and as soon as the forward
part of the body is withdrawn the lobster gives one or two final switches and is free.

The newly molted lobster has a very sleek and fresh appearance, and its colors
were never brighter or more attractive. Try to take it up in the hand, after some time
has elapsed, and it feels as limp as wet paper; but immediately after casting the shell
the muscles of the crustacean are hard and tense, probably from being in a state of
cramp or tetanus. Every part of the old shell down to a microscopic hair has been

206

BULLETIN OF THE BLTREAU OF FISHERIES.

reproduced in the new one, but in the latter the fringes of stiff setae are as soft as silk,
the stony ends of the claws, the rostrum, and every spine of the body so soft as easily
to bend beneath the finger. Possibly the hardest parts of the newly molted lobster are
the horny surfaces of the teeth of the stomach sac. The large claws are considerably
distorted, as well as some of the other parts, being compressed and drawn out to an
unnatural length. After getting clear of the old shell the animal is not inclined to
activity. It soon orients itself, however, resting in the usual way, and is capable of
moving about with some degree of agility by the flexure of the tail. Fishermen who
have had lobsters shed in their cars or traps have often been surprised by the ease with
which they sometimes slip through their fingers.

The length of the cast shell of this lobster was x i .25 inches, and shortly after the molt
the animal measured 12 inches from tip to tip. On July 17, four days after molting,
the length was a little short of 12.5 inches. The increase in length was thus very
nearly 1.25 inches. Very soon after molting the lobster is ready to take food, the body
plumps out to its natural shape, and no further increase in volume can take place until
another molt.

The increase in length of body at each molt in lobsters between 5.5 and 11.5 inches
is between 11 and 12 per cent. Increase in length diminishes beyond this period, yet
the volumetric increase of the entire body, especially the big claws, may be as great
or even greater. Beyond the twenty-second stage, according to Hadley, the male
grows more rapidly than the female.

WITHDRAWAL OF THE BIG CLAWS.

The shell of the large claw is molted entire without a rupture in any part. This
means that the great mass of muscles which fill its terminal joints must undergo disten-
tion and compression to an extraordinary degree, since it is all drawn through the con-
stricted base of the limb as wire is pulled through the holes of a drawplate. What
this implies will be best appreciated when it is realized that the cross sectional area of
the biggest part of the cheliped is more than four times greater than that at its nar-
rowest point, in the second joint.

The lobster is aided in accomplishing this feat by the elasticity of the muscles and
other tissues and by the removal of blood from the fine meat of the claw (pi. xl, and
fig. 3, pi. xlvi), as well as by the development of absorption areas in the shell of the
third and fourth segments of the cheliped. (PI. xxxvn, fig. 2, abs. a.) The muscles
of the big claw, which are pulled out like a stick of candy, are at first quite tense.
Very soon, however, they relax and, filling with blood and presumably taking up some
water, they assume their natural form, with proportional increase in size. The absorp-
tion areas, from which mineral matter is removed preparatory to the molt, are easily
distinguished in the hard-shell lobster, though less clearly defined. The shell of the
basal joint becomes a slender ring, but does not break.

At the time of the casting of the shell the large claws must be practically free from
blood, since, as Vitzou has pointed out, if the claw were to be increased in size it would

NATURAL HISTORY OP AMERICAN LOBSTER.

207

be next to impossible for it to be withdrawn without rupture. The older naturalists
used to explain the withdrawal of the large claws by a wasting of the tissues. The
lobster was supposed to become sick and emaciated, which was, of course, an error.
The most significant fact in this process is the displacement of the liquids which nor-
mally belong to these appendages. The terminal soft tissues of the claw are essentially
a sponge work of involuntary muscle fibers, to which the returning blood stream has
free access.

The changes in the armature of the lock forceps, which attend each molt in both
young and adult, are discussed in chapter vii.

MOLTING OF THE “HAMMER” CLAW IN THE SNAPPING SHRIMP, ALPHEUS.

It would be erroneous to infer that all relatives of the lobster in molting with-
draw the flesh of their big claws through the “drawplates” of the basal segments of
the limb. This is not true of certain species of the snapping shrimp, in which the great
“hammer” claws are proportionately larger than in the lobster.

On November 13, 1896, while at the zoological station at Naples, a large male of
Alpheus dentipes molted in a small aquarium at 3 o’clock in the afternoon. Prepara-
tions for this act had been going on for several hours, and were probably begun in the
early morning. In this case the muscular mass of the claw was withdrawn through a
crack, which extended along the outer margin of the propodus. This cleft was con-
tinuous, with a similar fissure involving the proximal segments of the cheliped and
extending through the basal ring. The great muscular mass of the hammer claw was
thus withdrawn without distortion. This fissure was assumed to correspond to a linear
absorption area, but I have not been able to repeat the observation.

CHANGES IN THE SKELETON PREPARATORY TO MOLTING.

At the time of the molt there is an intermediate membrane which makes its appear-
ance between the new and old shells. It is noncellular, has a gelatinous appearance, is
very transparent, and may be found adherent to the old shell after the molt is past.
It bears the impress of a mosaic of cells, which can be none other than the cells of the
chitinogenous epithelium. Vitzou is thus in error in supposing that this substance is
a secretion of chitinogenous epithelium underlying the new carapace, which it traverses
by endomosis. It must be either the first secreted product of the new shell or the
innermost layer of the old shell modified by absorption, if not derived from tegumental
glands.

In this cuticular membrane the parts which correspond to the cell boundaries of
the chitinogenous epithelium have the form of elevated ridges on the under side, and in
the center of each polygonal area there is a slight thickening. Reaumur a had in view
a similar structure in the crayfish when he spoke of a glairy matter “as transparent as
water, which separated the parts which the crayfish was soon to cast off from the rest

a Additions aux observations sur la mue des 6crevisses, Memoires de 1’ Academie Royale des Sciences, p. 263-274, 1 pi.
Paris, 3719

208

bulletin of the bureau of fisheries.

of the body, and which allowed these to glide smoothly over one another.” The old
shell becomes brittle, owing to the absorption of organic matter previous to molting,
and if the carapace is pressed between the fingers it will sometimes split down the back
in the longitudinal median furrow, but in most cases the shell does not crack in this
plane unless artificially compressed. In the course of the preparation for the molt the
lime salts of the shell are absorbed along the middle line of the carapace, leaving a
narrow, perfectly straight gutter extending from the spine or rostrum to the posterior
margin of the shield. The chitinous portion of the cuticle still remains, forming an
elastic hinge, on which the lateral halves of the carapace bend without breaking asunder.
In the molted shell there is also a linear membranous area on either side of the rostrum.
Absorption of the hard matter of the shell at these points tends to give greater latitude
to the movements of the two halves of the carapace. If you examine a hard-shell lob-
ster, you will fmd in place of the median furrow a blue line, drawn as if with pen and
rule. Below this line the epidermic cells of the skin become so modified as to bring
about the total absorption of the lime salts of the cuticle.

Other areas of absorption besides those of the great chelipeds, already described,
include the wide lateral margins of the gill covers or branchiostegites, which in life are
colored light blue, parts of the endophragmal skeleton, especially the roof of the pas-
sageway, in which are lodged the sternal blood sinus and part of the nerve cord, and
the endotergites, three small teethlike projections from the under side of the carapace,
on which the posterior gastric muscles are partly inserted. Rupture in the rostral
regions is further provided against by the narrow absorption areas on each side of it,
while the softening of the margins of the carapace makes the lifting of this from the
body an easy matter during the molt. The softening of the endotergites and apodemes
of the internal skeleton is also necessary to prevent injury to the soft tissues and to
permit their release.

The lobster, as we have seen, leaves its old envelope by drawing the anterior part
of its body backward and the abdomen forward through a rent in the soft membrane
between carapace and tail. The cuticular lining of the masticatory stomach and esopha-
gus comes out by way of the mouth, while whatever is molted from the intestine is with-
drawn from the anus. The intestinal molt of the larva is apparently much more exten-
sive than that of the adult. When the discarded carapace falls back into its natural
position we might, as Reaumur says of the crayfish, mistake the empty shell for another
animal.

THE GASTROLITHS, OR “STOMACH STONES.”

The gastroliths of Crustacea are found only in the lobster and crayfish, and according
to Patrick Browne, as noticed by Stebbing (259), in certain land crabs of the island of
Jamaica. Having been first discovered in the common river crayfishes of Europe,
they figured in the old pharmacopoeias as oculi seu lapides cancroriim, and have excited
the interest of naturalists from early times. Owing to their transitory character, they
are not commonly seen in the lobster.

NATURAL HISTORY OF AMERICAN LOBSTER.

209

If the shell of the lobster which is nearly ready to molt is removed, there will be seen
two glistening snow-white masses, one on either side of the stomach. A gastrolith
taken from a lobster 1 1 inches in length was an inch long, three-quarters of an inch wide,
and a quarter of an inch thick. Its outer convex side was applied to the sac in which it
lay, while its concave side was separated from the cavity of the stomach by the old artic-
ular lining of this organ. When the stomach is raised the gastroliths almost break
through its delicate outer wall by their own weight. They lie between the old cuticular
lining of the stomach, which may be stripped off, and its delicate outer wall, next to
the body cavity. The impression of the gastrolithic plate (pi. xxxm) is seen on the
new cuticular lining only. If the sacs in which they are formed are cut open, each
mass separates into hundreds of small ossicles or columns, the majority of which are
slender truncated prisms of irregular shapes and about one-fifth of an inch long. Each
ossicle resembles a piece of milk-white glass, with transparent edges, and is faintly
marked with transverse and longitudinal striations, like those seen in the cuticle.

The gastroliths, though a part of the cuticle, are not regularly cast off during the molt,
but are retained in the stomach; when the old lining of this organ is withdrawn, they
are soon set free, and breaking up into their constituent parts are speedily dissolved.
Consequently it has been supposed that they served the function of providing a supply
of lime for hardening the new shell. Messrs. Irvine and Woodward (165), however,
have proved that the amount of calcareous matter obtained in this way is only about
one one-hundred-and-eighty-sixth part of that of the entire skeleton, and therefore too
insignificant to be of any practical value. Lime, moreover, is at hand in abundance
in the form of the shells and skeletal fragments of mollusks and other animals, which
lobsters make free use of at the. time of the molt.

We have suggested that the gastrolithic plates or sacs in the walls of the stomach
are organs for the excretion of lime, and that the gastroliths represent the lime removed
from the absorption areas previous to the molt. Upon this theory their retention and
absorption is an incident of no special importance (see 149, p. 93).

The gastrolith of one of the common crayfishes ( Cambarus robustus) when 4 inches
long is about the size of a split pea, 7 millimeters in diameter by 5 millimeters thick.
It shows no divisions into ossicles, but is a hard mass. The convex face is dull white
and nearly smooth, while the flattened side presents a brown circular scar with a white
center. In form and appearance it suggests a small mushroom with the stem cut off
close to the cap. In sectional view it shows concentric striations.

Chemical analysis 0 has proved that lime salts as carbonates and phosphates
form about half the constituents of the hard shell, there being from three to five times
as much carbonate as phosphate. We also find that in the cast shell of the lobster the
proportion of organic matter present is considerably less than under other conditions.
An absorption of organic matter thus takes place during the period in which the new
shell is formed, and this fact explains the fragility of the cast-off shell. Small quantities
of alumina and silica are normally present in both the shell and gastroliths.

° See article by Prof. A. W. Smith, 252 of bibliography.

48299° — Bull. 29 — 11 14

210

bulletin of the bureau of fisheries.

The composition of the gastroliths is similar to that of the shell, a conclusion which
we should be led to draw from the fact that these bodies are specialized parts of the dead
chitinous integument. The same substances are found in both, but in different propor-
tions. The gastroliths are far richer in lime, chiefly in the form of carbonate (CaC03),
than is the shell, and the amounts of magnesium carbonate (MgC03), alumina (A1,03),
ferric oxide (F^Og), and silica (Si02) are more or less reduced.

Lime estimated as carbonate (CaC03) constitutes about three-fourths of the gastro-
lith, but less than two-fifths of the carapace. Lime reckoned as phosphate (Ca3(P04)3)
forms about io per cent of the gastrolith and but little less in the case of the shell ; about
io per cent of the gastrolith is water and organic matter, probably mainly chitin, and
the rest is made up of various salts and oxides. In the only molted shell analyzed
about 38 per cent was water and organic matter, while in two hard-shell lobsters this
percentage was considerably greater, 42.21 in one case and 51.80 in the other.

Since the total quantity of lime contained in the gastroliths is but a small fraction
of the amount necessary for building up the hard crust, the rapidity with which the new
shell hardens depends in some measure upon the individual, and particularly upon the
quality of its food. Lobsters when young and sometimes when adult not only eat their
own cast after molting, but swallow fragments of shells and other calcareous materials,
which are dissolved in the stomach and help to strengthen the new shell.

Williams (279), who has recently studied this subject, has added some important
facts to our knowledge of the gastroliths. He found that while absent in the larvae
they made their appearance at the fourth stage, when the shell begins to receive deposits
of lime, and at about the middle of this period. After the next molt the gastroliths
were dissolved in the course of a few hours, either remaining in place or falling to the
bottom of the stomach sac, to be later broken up. With their dissolution there was
observed a gradual hardening of the gastric teeth, mandibles, and later of the chelipeds
and other parts.

As soon as the gastroliths are dissolved [says Williams], the lobster attacks his cast, beginning to eat
the bristles and small parts and proceeding to devour more or less of the harder parts. The newly
molted lobsters seldom seriously attack their sloughs within three or four hours, and generally eat the
greater part of the cast within twelve or eighteen hours.

He therefore supports the older view that the gastroliths represent a store of lime
and other minerals reserved from the old shell for the immediate hardening of the new,
with the additional statement that this reserve is destined for particular parts — gastric
teeth, mandibles, and chelipeds — so that the cast and other calcareous matter within
easy reach may be quickly available.

Stebbing (260), who also has criticised the view that the gastroliths are primarily
excreted products, does not believe that such nicely adjusted structures can serve as
“mere off scourings of the body.”

The difficulties in the way of supposing that these interesting bodies are necessary
rather than incidental sources of lime to the newly molted lobster are by no means
removed by the observations quoted above. To be of service at all the carbonates of

NATURAL HISTORY OF AMERICAN LOBSTER.

21 I

the gastroliths must be dissolved, absorbed into the general circulation, and converted
into phosphates. There is no reason to suppose that the gastric teeth or any other
part can make exclusive use of this lime, or use it at all except through the roundabout
course open to all lime-absorbing cells. Moreover, the total amount of mineral matter
in the gastroliths is so small that when equally disseminated it is difficult to understand
how it could be of vital importance.

It seems altogether more probable that the parts mentioned by Williams are
hardest in the end because they have the hardest chitinous base in the beginning, and
that all parts receive only their due proportion of lime.

Assuming the problem of the gastrolith to be similar in both lobster and crayfish,
the spicular character of the former may have no special significance. In the crayfish
these bodies, as we have already seen, are solid stones, which, according to Chantran,®
are slowly ground down rather than dissolved, their complete dissolution taking upward
of three days in an adult animal.

Turning to the other side of the question, the absorption of lime from definite areas
of the shell is of the utmost importance. Deformity or death awaits every animal in
which the absorption areas are not duly formed. The production of such areas involves
the excretion of lime through the medium of the blood. Their actual development
proceeds, in some measure at least, with the growth of the gastroliths.

Accordingly, while the question may still be regarded as somewhat involved, we
still believe that the theory earlier given, that the gastroliths are primarily excreted
products and represent mineral matter removed from the shell in preparation for molt-
ing, and that their use for hardening the new shell is purely incidental, is the only one
which meets all the facts in the case with any degree of success.

If it could be experimentally shown that the gastrolith is essential to life after the
molt, as we now know it to be for the safe passage of the molt itself, a theory early
maintained but not satisfactorily proved, the present status of the question would be
changed.

HARDENING OF THE NEW SHELL.

A lobster which molted while under observation was watched particularly with
reference to the hardening of the shell. One hour after the molt the cuticle seemed to
the touch of the finger to be perceptibly hardened, but this may have been due to the
turgescence of the tissues. Eighteen hours after shedding the cuticle had a leathery
consistency, and the tubercles and spines had hardened slightly. The shape of all the
parts was perfectly normal. Four days after the molt, when the animal died, the
cuticle was still coriaceous, and but slight increase in the stiffness of any parts had
occurred.

Another animal which also molted in confinement was kept for a period of 25
days. The carapace at the end of this time was easily compressible between the thumb
and finger. The large claws could be made to yield in the same way, but not without

Comptes rendus de 1' Academic des sciences, t. lxxvui. Paris, 1874.

212

bulletin of the bureau of fisheries.

using considerable force. It was in the state which the fishermen designate as a “paper-
shell” or “rubber-shell” lobster. If sent to market it would have been classed as a
soft-shell lobster. It is possible, of course, that in this space of time an animal under
natural conditions would have become harder. It is safe to conclude, however, that
from 6 to 8 weeks are necessary, under ordinary conditions, to produce a shell which is
as hard as that cast off, and if the lobsters were destined for the market they would
probably be in a still better condition in io weeks or 3 months. Many lobsters with soft
shells are caught and sent to market, but their flesh is then watery and of inferior quality.
When cooked, the fine meat of the claws, which will serve as a good index of their con-
dition, shrinks to an almost unrecognizable remnant. According to the opinion of a
canner of lobsters in Maine, 7 pounds of soft-shelled lobsters in summer or fall will
yield no more than 4 pounds in spring, when the flesh is more solid.

RELATION OF WEIGHT TO LENGTH IN THE ADULT.

The lobster’s weight does not bear a constant ratio to its length, but is very variable
owing chiefly to the loss of limbs, and particularly of the great claw-bearing legs. These
alone represent from one-fourth to one-half of the weight of the animal, and probably
in all giants of the 20 to 30 pound class, which are invariably males, the weight of the
great chelipeds is fully two-thirds that of the entire body. The lost limbs are promptly
regenerated, as we have seen, but never completely without the intervention of one or
more molts, so that a lobster with an undersized claw is a common occurrence.

The length of lobsters is commonly measured from apex of rostral spine to the end
of the telson, not including its terminal fringe of hairs. More exact comparisons can
be made from measurements of the nondistensible carapace or back shell alone. This
method of measuring the lobster was adopted by the legislature of Maine in 1907, and
should be generally followed. The Maine laws require the marketable lobster to meas-
ure 4.75 inches from the beak to hinder margin of the carapace, which is equivalent to
a 10^ -inch animal under the old standard, the ratio of carapace length to full body
length being approximately 45 per cent for animals of average size. When the rostrum
is defective the total body length can be taken. Under such a relatively inflexible
standard the fisherman is not tempted to stretch his lobsters in order to put them
into the “counter” class, and to sell animals which are likely to die from injuries
thus received.

The weight is subject to considerable variation in consequence of molting, when
a dense armor is exchanged for a much lighter though larger one. In the soft lobster
the specific gravity of the solids and fluids of the body is considerably reduced, but
on the whole the weight is chiefly affected by disparity in the size of the big claws.

The male is heavier than a female of the same length, at least after passing the
8-inch mark. The 10-inch males are about an ounce heavier than females of corre-
sponding length. From this stage onward the balance in favor of the male becomes
most pronounced. Thus the n-inch male exceeds the female of this length by a full

NATURAL HISTORY OF AMERICAN LOBSTER. 213

quarter of a pound. In a lobster 12.5 inches long there is a difference in favor of the
male of 7.5 ounces.

It is evident from the data earlier presented (see J49, table 31) that the greater
size of the male, which is a sexual characteristic, does- not appear until the animal has
passed the 8-inch limit. At this period the sexes are of about equal weight, but from
this point the male surpasses the female in weight, owing chiefly to the greater develop-
ment of the large claws.

The average weight of females without and with eggs proves that females with
spawn are in a poorer condition or weigh relatively less than females without eggs
attached to the body. In one-third of the cases recorded the weight of females with
eggs was actually less than that of females of the same length without eggs. In the
10-inch series 184 females were examined; 36 of them had eggs and weighed on the
average but one-tenth ounce more than those without eggs. The average quantity of
eggs borne by a 10-inch lobster is 1.73 fluid ounces, and since a fluid ounce of lobster
eggs weighs very nearly an ounce avoirdupois, the average weight of the 10-inch female
deprived of her eggs is 22.13 ounces, as compared with 23.76 ounces, the average weight
of nonegg-bearing females of this size. There is thus a difference of 1.63 ounces in
favor of the female without eggs. In the case of the 9.5-inch female lobsters, where
169 in all and 24 bearing eggs were examined, the average weight of the spawners was
less by 0.09 ounce than that of the corresponding females without eggs.

The facts which have just been stated do not support the conclusion of Buckland
and his associates on the fisheries work in Great Britain that “the lobster, when berried,
is in the very best possible condition for food.”

The average weight of the 10.5-inch male lobster (the present legalized length limit
in Maine, New Hampshire, and certain districts of Canada) is about 1.75 pounds, a cor-
responding female without eggs weighing about an ounce less. At 9 inches (legalized
in New York, Rhode Island, Connecticut, in Massachusetts since 1907, and in certain
parts of Canada) the average for both sexes is nearly 1.25 pounds. The lobster 8 inches
long (the present legal gauge for England, Norway, and parts of Canada) of either sex,
has an average weight a little short of a pound, or 15.16 ounces. At the 12-inch length
the male weighs approximately 2 pounds 12 ounces, the females being about 2 ounces
lighter, while lobsters 15 inches long will weigh on the average 4.25 to possibly 4.5
pounds.

A lobster 17.75 inches long weighed nearly 10 pounds (though in this case the
cutting claw was undersized), and the mammoth specimens recorded in table 1, weighing
from 19 to 34 pounds, varied only from 19.5 to 23.75 inches in length. Indeed between
the 18-inch and 20-inch length, as well as beyond this limit, great variation is seen in
the weight of normal individuals of either sex of the same length as in the case of smaller
lobsters, and due to the same causes, namely, variations in the size and the correspond-
ing weight of the large claws or to the condition of the shell with respect to molting.
Beyond the 20-inch size a slight increase in length may imply a great addition to the
weight.

214

BULLETIN OF THE BUREAU OF FISHERIES.

PROPORTION OF WASTE TO EDIBLE PARTS IN THE LOBSTER.

Atwater (n), in his chemical analysis of the flesh of the lobster, gives the propor-
tion of the edible parts and shell as follows:

Per cent.

Total edible portion 39-77

Shell.- 57.47

Loss in cleaning , 2.76

100. 00

The proportions of water and dry substance in the edible portion are estimated as

follows :

Water 82. 73

Dry substance 17-27

100. 00

In this relation the analysis given in table 3 will be of interest. These data were
obtained from a 13-inch (boiled) female lobster, with shell of medium hardness. Liter-
ally all of the soft and edible parts were carefully removed from the skeleton and
weighed. This, without doubt, accounts for the higher percentage of “edible” parts
obtained when compared with the result quoted above, it being assumed that all of the
soft tissues of this animal are edible and wholesome excepting the stomach and intestine.

The flesh of the lobster is rich in nitrogenous or proteid substances and contains a
considerable amount of phosphorus and sulphur. Its nutritive value as compared with
beef taken as a standard is 61.97 Per cent (IJ)-

Table 3. — Showing Relation of Edible to Waste Parts in the Lobster.

Edible parts.

Pounds.

Ounces.

Waste.

Pounds.

Ounces.

(1) Tail muscles

8 H

(8) Shell and "lady” or

(2) Meat of great claws, including joints of great cheli-

stomach sac

(3) "Cream, ”or clotted blood from great chclipeds

(4) Fine picked-out meat from linkwork of body and

smaller appendages, including gastric, mandibu-

lar muscles, and green glands

(5) "Cream,” or clotted blood from body under shell . .

27/&

(6) "Coral, ” or ovaries

(7) " Tomally, ” or liver

2 Yz

Total weight of claw and tail meat, 1 pound.

Total weight of items i to 9, 3 pounds 9% ounces.

Estimated living weight, 4 pounds 4 1/2 ounces.

Dead weight, 3 pounds 9% ounces.

Percentage of clear meat in claws and tail, 27.

Percentage of all clear meat and edible parts, 55.

Total cost at current retail-market price, at 25 cents per pound, at Tilton, N. H., June 27, 1903, 90 cents.
Cost per pound of clear meat of big claws and tail (items 1 and 2), 90 cents.

Cost per pound of clear meat and other edible parts not usually saved (items 4-7), 45 cents.

Chapter V.— ENEMIES OF THE LOBSTER.

PREDACEOUS ENEMIES.

The adult lobster, whether with eggs attached to its body or not, is the prey of numer-
ous fish which feed upon the sea bottom, like the sharks, skates, and rays. When of
considerable size or in soft condition it is also devoured by the cod, pollock, striped
bass, sea bass, tautog, and probably by many other species. In fact every predaceous
fish which feeds upon the bottom may be looked upon in general as an enemy of the
lobster.

Next to man with his traps, the codfish is probably the most destructive enemy
of the lobster, for it not only takes in the soft and hard shell animals alike up to 8 inches
or more in length, but is very partial to the young from 2 to 4 inches long.

If the lobster is thus attacked and destroyed in large numbers by fish after it has
acquired the habits of the adult and has many devices to avoid its enemies, what shall
we say of the destruction which is wrought on the young during the first three or four
weeks of their life? From the time of hatching up to from the fourth or fifth stage the
young lobster swims at the surface and becomes an easy prey to all surface-feeding
fish, some of which, like the menhaden, roam about in vast schools, straining the water as
effectively as the towing net. When lobsters settle in relatively shallow water the
greedy cunners or even fish of smaller size would doubtless prove vastly more destructive.
During this period the lobster measures from one-third to three-fifths of an inch in length,
and is not only helpless in the hands of its animate enemies, but is subject to a vast
amount of indiscriminate destruction from the forces of inanimate nature.

parasites and messmates.

But two parasites in the strict sense have thus far been known to infest the lobster,
although it is probable that others will he discovered. One of these, a trematode worm
(. Stichocotyle nephropis) first noticed in the intestine of the Norwegian lobster, was later
detected in the American form, about 2 per cent of these animals being infested by it.
Its final host is probably some species of fish which preys upon the lobster, but the adult
trematode is unknown.

The only other strict parasite which has been found to trouble the adult lobster is the
large gregarine ( Gregarina gigantea), discovered in the intestine of the European lobster
by Van Beneden (269).

215

2l6

BULLETIN OF THE BUREAU OF FISHERIES.

The European lobster is commonly infested with a small colorless worm, Histriob-
della homari, of remarkable habits and doubtful relationship. Discovered in 1853 by
Van Beneden on this lobster’s eggs at Ostend, it was regarded as a larval serpulid, but
later ( 108 ) shown by him to be an adult and placed among the leeches. An account of
its anatomy was given by Foettinger (108) in 1884, but for the most exact anatomical
analysis of this curious semiparasite or commensal we are indebted to Shearer (324),
whose work has but recently appeared. He found that it not only lived among the eggs
of the berried lobster, but took up its abode in the branchial chamber and on the gills of
both sexes also, passing readily back and forth when its host was a female in berry. It
crawls slowly, but is more active among the lobster’s eggs, to which it attaches its own
ova freely, as well as to the carapace side of the branchial chamber. It is very sensitive to
changes in the sea water, and its selection of such lodgings seems to indicate clearly the
need of an abundant supply of oxygen. Development is direct, there being no larval
stage, and little is known of its distribution or the means by which this is effected.
Though possessing toothed jaws, and though seen to bite one another, these parasites
are not known to molest either the gills or eggs of their host, and since they often devour
diatoms in quantity they may be the lobster’s bosom friend rather than its enemy.
So far as known at present, Histriobdella is not attached to the American lobster.

But although parasites are rai'e, the lobster is encumbered with a great variety of
messmates, which attach themselves to the external shell. Whenever the lobster is
confined in inclosures, or compelled for any reason to lead a sluggish life, the common
barnacle fixes itself to the arched carapace and begins to secrete its tent-like covering
as securely as it might upon a stone; mussels of various kinds insinuate themselves in con-
venient angles of the shell and joints, and small tunicates sometimes become attached
firmly to the underside of the shell between the legs. Tube-forming annelids, lace-like
bryozoa, form incrustations in various parts, and red, brown, and green algae often
decorate the antennae and carapace with long streamers which are waved with every
movement of the animal. At each molt the lobster of course frees itself completely
from these troublesome companions. (For fuller account of parasites and messmates
see 749, p. 122-124.)

When young lobsters are hatched and reared in confinement they are apt to be
troubled with a variety of parasitic fungi and algae, including many species of diatoms, as
well as stalked protozoans. Young lobsters captured at sea seem to be peculiarly free from
foreign matters of every kind, but when the young of almost any crustacean are confined
they are liable to become clogged with solid organic and inorganic particles of many
kinds, including living bacteria, spores of fungi, and diatoms. The hairs which garnish
the body and appendages of crustacean larvae serve to gather up and hold particles
from the water, so that one of the first considerations in the artificial rearing of these
animals is to give them as clean a water supply as possible. Old lobsters, in which the
molting periods have become very infrequent, are the worst sufferers from enemies of this
kind, but the physiological condition of the animal is a most important consideration.

NATURAL HISTORY OF AMERICAN LOBSTER.

217

diseases and fatalities of the lobster.

There are few specific diseases to which adult lobsters are subject so far as known, yet
they sometimes die off so rapidly as to lead one to suspect that they have fallen a prey
to infectious disease.

Mr. N. F. Trefethen, of Portland, Me., relates the following experience: In May,
1893, he placed 100,000 lobsters in a pound at South Bristol, the area of which is about
3 acres. Very soon they began to die, and in a few days all of them were dead.
There was from 12 to 13 feet of water in this pound at flood tide and not less than 9
feet at low tide. The pound was probably very much overstocked, but it is difficult
to understand why these lobsters should have all died so suddenly, unless they were
either poisoned or attacked by disease.

In the summer of 1889 a lobster with a large bunch on the side of the carapace was
captured in Vineyard Sound. On the top of this tumoid growth was a crater-like depres-
sion covered with a membrane. This was probably a sore resulting from a wound
which the animal had received in the back, and which failed to heal. A similar case is
mentioned by Rathbun. Further, according to Prince ( 218 ), Professor M’lntosh has
described a tumor-like growth in a large lobster which originated in the wall of the
stomach sac, finally perforated the carapace and caused its death.

In another place I have alluded to the experience of the U. S. Bureau of Fisheries
at Woods Hole in feeding the young lobsters with shredded menhaden. The larvse
became infected with a fungus, which spread to all parts of their tissues and was soon
fatal.

To paraphrase the words of Hardy,® the lobster, like many other aquatic animals,
is confronted by the same problem that has so long puzzled the shipbuilding world.
Larvse and spores are constantly settling upon the exposed surfaces of its body, where they
tend to develop growths which would interfere with their movements unless some
method of destroying or removing them were adopted. Hardy believes that “the
presence of a film of soluble slime on the surface of an animal immersed in water would,
like the copper sheathing of ships, mechanically prevent the occurrence of parasitic
growths by continually forming a fresh surface,’’ and further that this slime may in
some cases have a specific poisonous power, directed chiefly against vegetable parasites.

The lobster apparently secretes no slime, but its shell is studded with the openings
of the tegumental glands, the exact function and role of which is still in doubt. At all
events it will do no harm to raise the question whether these bodies may not help to
free the animal from such pests. That molting alone is not able to do this and that
some additional aid is often needed is amply proved by the great variety of messmates
or semiparasites which we have described.

Lobsters from a few inches in length up to the greatest size are sometimes driven
ashore and stranded on the beach, where, stunned or crushed by the force of the waves,

a Hardy, W. B. The protective functions of the skin of certain animals. Journal of Physiology, vol. xiii, no. 3 and 4.
London, 1894.

218

bulletin of the bureau of fisheries.

they are often left to perish. Well-nigh incredible accounts of the “windrows” of dead
lobsters left by fierce storms on the shores of New Brunswick and of other maritime
provinces were current in the earlier days of the fishery. Thus Prince ( 218 ) speaks of
a memorable storm along the Shippegan shore, Gloucester County, New Brunswick,
in 1873, and states that as many as 2,000 dead lobsters were counted in the distance of
2 rods.

The writer quoted above also speaks of the fish crow ( Corvus frugilevus ) as very
destructive to lobsters on parts of the coast of Nova Scotia, where he says “when the
tide goes down these birds destroy the lobsters left amongst the seaweed. They pierce
the shield of the lobster where the heart and main blood vessels are situated, and the
crustacean is at once rendered helpless and is devoured by its assailant.” I have seldom
known the lobster to be stranded in this way in calm weather. The adolescent lobsters,
which alone remain in near the shores, ordinarily go deep down among the loose stones,
where neither crow nor any other bird could possibly dislodge them.

Chapter VI.— ANATOMY OF THE LOBSTER, WITH EMBRYOLOGICAL AND

PHYSIOLOGICAL NOTES.

Both the lobster and the crayfish have long been regarded as classical exponents of a
zoological type and have figured so prominently in text-books that the elementary facts
of the anatomy of few invertebrates are better known; yet there is still a wide field for
more exact research in nearly every direction, as we have found whenever it was possible
to dip below the surface. In the present chapter it will be necessary to restate certain
elementary facts, but my embarrassment would be greater were this work intended solely
for professional zoologists, who will probably find more that is new in the chapter which
follows.

In attempting to give a fairly consistent account of the lobster’s anatomy I shall
not hesitate to enter into details, but shall endeavor to emphasize those parts of most
zoological interest from the standpoint of morphology, physiology, and development.
Numerous anatomical drawings are given, including the entire series of adult appendages,
which may serve for more exact comparisons with the larval stages than have been
possible hitherto.

THE BODY.

The lobster’s body (pi. xxxm and table 4), which the fisherman compares to a pistol
in shape, but holds by the “barrel,” is made up of a series of 21 somites or body segments
(or of 18, omitting 3 of doubtful value), all but the last of which bear paired and jointed
appendages. The first 14 are united into one piece called the cephalo-thorax or “barrel,”
while the last 7 form the flexible abdomen or tail. This primitive segmentation which
is expressed chiefly in the exoskeleton or the hard and soft skin extends also to the
nervous system, as well as to certain muscles and blood vessels, but does not involve
the soft parts of the body as a whole. A cuticle, which is strengthened with lime and
other minerals to form a hard crust wherever greater protection or rigidity is needed,
follows every inward fold of the skin and covers every part of the body down to a micro-
scopical hair.

The skeletal parts of head and thorax are fused on the upper and lateral surfaces
to form a large cephalo-thoracic shield or carapace, often called simply the “shell,”
which is “buttoned” on to the tail by small overlapping pleura of the first small somite
of this part. The carapace is marked and sculptured in a very definite manner by
symmetrical folds or grooves, tendon marks, and absorption areas, not to speak of pro-
tective spines, and smaller tubercles, fringing sensory hairs, and the very minute depres-
sions with which it is stippled all over, the hair pores to be later described. The light
median stripe which runs, as if drawn with pen and rule, from the rostrum to the hinder
border of the carapace represents an absorption area of the greatest importance to the
molting lobster. A prominent fold known as the cervical groove crosses the carapace

219

220

bulletin of the bureau of fisheries.

at a point about midway on the back to a triangular depression, representing a tendon
mark, and is thence continued forward on either side as a groove, which ends between
the antennae and the mandibles. In a soft lobster a penknife can be readily inserted
into this fold on the midline. Inwardly the pocket is continued into three divergent
endotergites, which give attachment to parts of the posterior gastric muscles, but are
absorbed previous to molting. Immediately below the forward end of the groove is
seen the “grater,” a peculiar roughened area of the shell at the outlet of the branchial
cavity; just before reaching this place the groove rises slightly, as if to avoid a promi-
nent swelling, which marks the position of the ball of the outer hinge of the mandible,
to be seen upon opening the branchial cavity. A branchio-cardiac line passes backward
from each tendon mark toward the hinder border of the carapace, and with the cervical
groove divides it into cardiac, gastric, and branchial regions. These lines are obscure
in young animals, but become prominent grooves later, and deep furrows in lobsters of
mammoth size. The gastric mill underlies the shell immediately in front of the cervical
groove; a puncture behind this fold draws blood from the pericardium or the heart,
while one below the branchio-cardiac line pierces the gill cover to the branchial chamber.
The meaning of other tendon marks and muscle impressions on the carapace is given
in a later section. Of the last io thoracic legs in the decapod, the first pair bear the big
claws in the lobster and are its largest and most characteristic appendages. Its smaller
and slenderer legs are chiefly ambulatory and sensory. The tail carries at either side
on its under surface a bank of elastic oar-like feet of simple type, the swimmerets or
pleopods for forward swimming, while the greatly enlarged and displaced sixth pair,
or uropods, make with the telson the tail-fan already referred to.

INTERNAL SKELETON AND HEAD.

If we examine a well-prepared skeleton of a lobster we see that besides the outer
hard crust there is a delicate internal skeleton, consisting not only of hard strap-shaped
tendons at the joints of the limbs, but of a complicated linkwork of very thin plates or
apodemes (pi. xxxm and xli). These unite to form partitions between successive sterna
and their appendages in the cephalo-thorax, and form an internal or endophragmal
skeleton. This intricate structure is produced by infoldings of the epidermal layer of the
skin in the sternal and epimeral parts of the cephalo-thorax. The apodemes of which it
is composed, are formed like the rest of the exoskeleton from matter secreted by the
epidermis. Each plate or rod is thus double in origin, being formed in a flattened
pocket like the tendons of the legs ( tp , fig. i, pi. xliii).

According to Huxley “ four apodemes are originally developed as ventral folds of
the skin between any two successive somites of the body, the anterior wall of each
pertaining to the somite in front, and the posterior wall to the somite behind. These
four apodemes thus form a single transverse series, the two nearer the middle line being
called the endosternites, and the two farther removed the endopleurites. The linkwork

“Huxley, T. H. The Crayfish, p. 158. New York, 1880.

NATURAL, HISTORY OF AMERICAN EOBSTER.

221

which thus arises by the repetition of simple units on the ventral side of the thorax
becomes more complex through the divergence and coalescence of both endosternites
and endopleurites at a higher level to form an archway for the sternal sinus. The roof
of this passage is discontinuous, being formed by the fusion on the midline of the inner
processes or mesophragms of the endosternites of each side, while their outer processes
or paraphragms unite with corresponding horizontal plates of the endopleurites.

The endophragmal skeleton greatly increases the area for the attachment of muscles,
and serves to bind the somites of the cephalo-thorax together with greater rigidity, as
well as to protect important organs, for not only does the archway securely lodge the
large blood sinus, but it also gives passage to the nerve-cord, access to which from above
can not be had without cutting through its roof (pi. xxxm and xxxiv). Since, as is
well known, this linkwork is shed in one piece, how do the central nervous system and the
parts adjacent to it escape unharmed? I have never heard this simple question raised,
but the answer is given by the molted shell, in which it will be seen that the roof of the
archway is completely absorbed as well as a large part of the intersegmental and dividing
partitions of the bulkheads referred to above, so that the whole under surface of this
part of the body with the delicate gills can be withdrawn with impunity.

The endophragmal skeleton bears the hinges for the articulation of the limbs,
the arrangement of which is peculiar (pi. xxxvn and xxxvm). The central hinges
which lie close to the mid-line are all cups and are borne on the sterna and close to the
endosternites, while the outer or peripheral hinges are all balls and are borne on the
epimeral surface of the branchial cavity, close to the endopleurites. The transverse
partitions are parallel with the axes of articulation of the appendages in successive somites.

The hard skeleton of the lobster’s head immediately in front of the mouth, repre-
senting apparently the sterna of somites ii to iv, consists of a conspicuous plate shaped
like an Indian arrowhead or spear, with the point drawn out into a sharp spine lying
between the first segments of the lesser antennae, while its broad base, raised into a
ridge, bears the soft upper lip or labrum; immediately in front of the ridge this triangular
plate is traversed by a deep furrow, in the midst of which lies a small closed pit, most
obvious in a soft-shelled animal. This marks the position of a median endosternite to
which are attached certain small muscles leading ventrally to the esophagus and
dorsally to the membranous covering of the brain.

Upon examining the skeleton of the head from the inside, it is seen that the epimeral
and tergal parts are fused to form a ring into which the eye stalks open, close to the
brain. On the upper side at the base of the rostrum the ring forms a solid bar, which
Professor Huxley thought might represent the tergum of the antennulary somite in the
crayfish, and from either side of this bar spring two large leaf-like divergent plates,
the procephalic processes, to which the anterior gastric muscles are attached. Below
the ring the calcified epimeral surface surrounds the large paired openings for the anten-
nules and antennse, and is continued to form the wall of the branchial chamber on
either hand.

222

BULLETIN OF THE BUREAU OF FISHERIES.

APPENDAGES.

The 20 pairs of appendages of the lobster are developed as tubular folds or out-
growths of the body wall, and consist of ectoderm with mesodermic cores, a rule which
seems to be broken only in the case of regenerating limbs, where ectoderm appears to
contribute to the renewal of both muscles and nerves. The order of embryonic develop-
ment is: (i) Antennules, (2) mandibles, (3) antennae, (4) maxillae and the thoracic
limbs in regular succession. Four pairs of swimmerets (somites xvi-xix) are released
together in the second larval stage (fig. 41); the uropods in the third stage (fig. 42)
and the first pair of pleopods, which are the last to appear, are not usually recognizable
until the sixth molt or later.

The eyestalks, which are omitted from the enumeration given above, and the
antennules are prostomial in origin, while the originally postoral antennae reach a
position in front of the mouth by the twentieth day, when the compound eyes are dis-
tinctly lobate. Segmentation in the limbs is a gradual process, constrictions early
marking future joints, while the division into outer and inner branches begins at the
apex of the appendage except in the antennules, as noted below. Most parts of the
adult appendages are recognizable in the first larva, and all, excepting those of the xv
somite, in the lobsterling. From the fourth stage on through the adolescent period
the changes are gradual and relatively slight, excepting only those which involve the

Tabes 4. — The Body Segments and Appendages of the Lobster

Divisions of body.

No. of
somite.

Name of somite.

Name of appendage.

Functions of appendage.

First antennal

Antennule

Olfactory cr chemical, chiefly through
outer branch, and static.

Head (6)

Second antennal

Antenna

Tactile chiefly, and probably chemical

Mandibular

Mandible

Crushing and triturating small, hard parts
of food.

First maxillary

First maxilla

Masticatory and chemical, but chiefly for
passing the food.

Second maxillary

Second maxilla

Respiratory chiefly; also chemical, masti-
catory, and for passing on the food.

' VII

First thoracic

First maxilliped

For passing, and like the maxillae possibly
subserving the chemical sense.

VIII

Second thoracic

Second maxilliped ....

For transference of food, the chemical sense,
and respiration.

Third thoracic

Third maxilliped

Chiefly masticatory, with brushes for clean-
ing.

Thorax (8)

Fourth thoracic

Great cheliped, or first
pereiopod.

Chelate; big claws adapted on one side for
crushing and on other for seizing and
rending prey; respiratory, tactile, and
possibly olfactory.

Fifth thoracic

Second pereiopod

Chelate; ambulatory, tactile, and possibly
with chemical sense, for seizing, testing,
and transference of food; respiratory.

XIII

Seventh thoracic

Fourth pereiopod

Nonchelate; the same

XIV

Eighth thoracic

Fifth pereiopod

Non chelate; the same, and for cleaning
swimmerets.

NATURAL HISTORY OF AMERICAN LOBSTER.

223

great che'iipeas and the first pair of swimmerets. The complex and varied relations
of the successive somites and appendages of the lobster in the larval and adult state are
outlined in table 4.

In their type form (fig. 2 and pi. xxxvi, fig. 5) the appendages consist of an inner
and outer branch borne on a basal stem, known respectively as endopodite, exopodite,
and protopodite. The protopodite is composed of two segments, a proximal coxa, or
coxopodite, and distal basis or basipodite. The coxa of each limb from the maxillae to
the fourth pair of pereiopods (somites v-xiii) bears a hairy respiratory plate or epipodite,
from which rises a gill or podobranchia on all but the first two of these somites. The
primitive type of crustacean limb was probably biramous, since in the course of develop-
ment we frequently find the uniramous condition produced by loss of the more transi-
tory exopodite, and further, since the foliaceous form of appendage of the lower branehio-
pod Crustacea is secondarily assumed by certain of the mouth parts of the lobster and
other decapods. The undivided form of limb is permanently preserved in metameres 1
and x-xv, in the last of which the appendage is modified in the two sexes to perform
distinct functions. The origin of the two-branched antennules will be considered
presently. The exopodite is frequently abortive, or multiarticulate and elastic, as in
the swimmeret, a condition which the endopodite has also preeminently assumed in
the long whips of the antennae.

with their Chief Functions and Modifications in Larva and Adult.

Relation of appendage to type form.

Relation of adult to embryonic and larval ap-
pendage.

Apertures of body.

Doubtful; stalk in two segments

Doubtful. Basal segment lodges statocyst sac. . .

Exopodite wanting; exopodite reduced to scale,
and endopodite irregularly segmented.

Biramous; two distal segments of palp supposed
to represent the endopodite.

Transitory ocellus in first larva; compound eye
relatively large, and stalks short.

Bifid, and later uniramous in embryo; finally bi-
ramous in first larva; inner flagellum a secondary
outgrowth from primary stalk. Prostomial.

Bifid, and later completely biramous in embryo;
poststomial in origin, but later advance in front
of mouth.

Body and palp at comparatively late embryonic
stage.

Pore of statocyst on up-
per surface of basal
segment.

Papilla for opening of
renal organ on coxa.

Mouth, screened by
labru'm, between
mandibles.

Foliaceous; exopodite wanting; endopodite of
two modified segments.

Biramous and foliaceous; respiratory fan formed
by fusion of exopodite and epipodite.

Biramous and foliaceous, and like maxillae, with
protopodite modified for testing and passing
the food. Endopodite 2-jointed.

In type form; endopodite 5-jointed, and epipo-
dite with rudimentary gill.

In type form, modified for mastication, and
cleaning; second and third podomeres fused,
and exopodite reduced. Epipodite with func-
tional podobranchia in ix-xiu.

Uniramous through loss of exopodite in fourth
stage. Second and third podomeres modified
for autotomy, and fused “breaking joint” be-
tween them.

Uniramous through loss of exopodite in fourth
stage.

Early larval condition similar to adult, but endo-
podite unsegmented.

First larval condition similar to adult

The same, but epipodite without fold for “bailer ” .

First larval state similar to adult

In first larva with long swimming exopodite, lost
at fourth stage, and third joint free; no cleaning
brushes, and no teeth on ischium.

Biramous to fourth stage. Big claws nonprehen-
sile in first larva; of toothed type in fourth, and
symmetrical up to sixth or seventh stage. Tor-
sion of limb completed at fourth stage, after
which big claws are horizontal, and dactyls face,
opening toward mid-line of body.

Swimming exopodite shed at fourth stage

The same

The same, without epipodite and podobranchia. .

The same

The same; torsion of terminal segments away from
mid-line of body completed at fourth stage, when
limb is directed backward.

Oviduct opens on coxa.
Seminal receptacle.

Vas deferens opens on
coxa.

224

bulletin of the bureau of fisheries.

Table 4. — The Body Segments and Appendages of the Lobster with

Divisions of body.

Abdomen (7).

No. of
somite.

Name of somite.

Name of appendage.

Functions of appendage.

Modified in male for copulation, and re-
duced in female to prevent attachment of
eggs. Unirainous.

Biramous; for forward swimming; in female
for holding and aerating the eggs, and pos-
sibly for secreting the glue by which they
are fastened to certain of the setae; tactile,
with chemical sense in doubt.

XVII

XIX

XXI

Sixth abdominal

Sixth pleopod, or uro-
pod.

Enlarged and modified for forming with
telson, the tail-fan, for backward swim-
ming; tactile.

In the typical thoracic leg (pi. xxxviii) the endopodite is divided into 5 segments,
which, with the two divisions of the protopodite, give the limb 7 podomeres, numbered®
and named from base to apex as follows: (1) Coxa or coxopodite, (2) basis or basipo-
dite, (3) ischium or ischiopodite, (4) meros or meropodite, (5) carpus or carpodite, (6)
propodus or propodite, and (7) dactyl or dactylopodite. These successive segments
are articulated to the body and to one another by soft membrane and usually by hinge
joints which limit the movements of each to a single plane at right angles to the articular
axis, or to the line joining the two hinges; each segment, with the exceptions to be
noted later, is actuated by opposing muscles, a larger flexor and a smaller extensor, the
fibers of which are implanted over the hard shell of their respective segments and are
inserted on strap-shaped tendons which react on the distal podomere (fig. 1, pi. xli).
The tendon is derived from an ingrowth or flattened pocket of interarticular membrane
(fig. 2, mb., pi. xli, and fig. 1, tp., pi. xliii), and is sometimes closely united to the shell of
the distal segment. Each joint or articulation is therefore crossed by tendons which
belong to the proximal podomere and pull on the distal one.

In the successive somites of the tail the axes of articulation are all parallel, and
at right angles to the longitudinal axis of the body so that movement is limited to the
vertical plane. In the appendage, on the other hand, the direction of the axis of articu-
lation varies in successive podomeres (see figs. 6 and 7) ; moreover the initial direction of
movement of the base of each limb, which depends upon the angle which its articular
axis makes with the long axis of the body, varies greatly from head to tail (1350 in the
mandibles, about 550 in the great chelipeds, and 90° in the swimmerets). Accord-
ingly each segment acts as a lever of the third order, and the successive thoracic limbs
are capable of universal movement, and in a variable field. By reference to figures

a This order seems preferable to the reverse, which is sometimes adopted, since the protopodite has been less modified
than either of its branches, and we thus avoid the ambiguity of speaking of the seventh segment of a pleopod or of an
antenna

NATURAL, HISTORY OP AMERICAN LOBSTER.

225

their Chief Functions and Modifications in Larva and Adult — Continued.

Relation of appendage to type form.

Relation of adult to embryonic and larval ap-
pendage.

Apertures of body.

Uniramous, presumably through loss of exopo-
dite.

Appear as buds in fifth to eighth stage, and sexu-
ally differentiated in eighth to tenth stage.

In type form, with endopodital spur in male

Appear as bifid buds beneath cuticle of first larva;
released as rudimentary limbs in second larva;
fully functional at fourth stage.

The same, with protopodite undivided, and
2-jointed endopodite underlying exopodite.

Appear as buds at base of telson in second stage;
released in third and completely functional in
fourth.

Bifid in an embrvo of two weeks; later elongated

and forked; released in larva as a triangular
swimming plate, with terminal fringe of large
spines and small setae, which are more distinctly
plumose and greatly elongated at the fourth and
later stages.

base.

1 and 2, plate xli, the working of this effective mechanism is readily understood. In the
sectional view of the big claw and walking leg the tendons of the terminal joint lie in
the plane of the paper, and the axis of articulation is at right angles to it; a contraction
of the large flexor muscle (/?. 6) pulls on the large inner tendon and thus closes the
claw, while an impulse sent into the extensor (ex. 6) draws on the opposite tendon (t. 6),
which springs from the opposite side of the dactyl, and thus opens the claw. Contrac-
tion of the flexor of the next segment (fl. 5) would raise the whole claw toward the
eye, and so on. In this case, where considerable power is required, there is a double
or divided tendon for this muscle. Owing largely to the variation in the field of move-
ment of the successive pereiopods, referred to above, the lobster is able to cover a
wide front in defense, move forward, sideways, or backward, reach every part about
the mouth, and scratch the underside of its tail.

Whether the stalked eyes of decapods are metameric appendages or not is a question
upon which zoologists are not agreed. In the lobster the eye-stalk (fig. 1, pi. xxxv) is
composed of two segments, the basal of which is minute, and imperfectly calcified, as
in the protopodite of the swimmeret, and that flagella-like outgrowths occasionally
follow partial excision or injury of the eye is well known. “I think,” says Professor
Brooks in his monograph on Lucifer, ‘‘that the presence of a distinct ocular segment
in Squilla compels us to recognize an homology between the stalked eyes and an
ordinary appendage, although it is no doubt true that all the groups in which stalked
eyes occur can not be traced back to a common ancestor, and also true that the stalked
eyes themselves can not be traced back to ordinary appendages.”

The first antenna (fig. 4, pi. xxxv), as we have seen, is first in the order of embryonic
development, arising on about the ninth day, just behind the thickenings which form the
optic diks, and before the mouth invagination is formed. The latter appears a few hours
later than the antennules, and on a line drawn through their posterior margins, so that
these appendages are essentially prostomial. The mandibles come next in order, followed
48299° — Bull. 29 — 11 15

226

BULLETIN OF THE BUREAU OF FISHERIES.

in a few hours by the second antennae, both arising as simple buds, and all three pairs
become concentrated about the mouth in the early egg nauplius stage, which is thus
reached at the tenth or eleventh day. Both pairs of antennae are then distinctly divided
at the tips, as if about to branch, but the second pair only becomes biramous, the
first remaining as single constricted stalks up to near the end of embryonic life.
When the larva emerges, what is to be the inner and slenderer branch of this

appendage is seen arising as
a small bud from the base
of what becomes the outer
and thicker flagellum (fig.
34). The inner branch of
the antennule is therefore
probably not homologous
with an endopodite. The
outer branch develops its
club-shaped “olfactory”
setae in the second larval
stage, and remains very
short and stout up to the
fourth or fifth stages, when
it rapidly lengthens.

It should be noticed
that the lower or sternal
part of the head faces for-
ward instead of downward,
as a result of cephalic flexure
which arises in the course
of embryonic development;
in consequence of this the
anterior sterna are bent up-
ward through nearly a right
angle, so that the eyestalks
and both pairs of antennae
are directed forward, and
their originally anterior
faces have become their up-
per sides. (PI. xxxiii.)

Assuming that neither the eyes nor antennules are metameric appendages, and
that the telson is not a true somite, the body would consist of a prostomium bearing
the two pairs of articulated processes named, eighteen metameres, and a terminal telson,
the first four somites being fused with the prostomium to form the head, with appen-
dicular antennae, mandibles, and maxillae.

Since it will be necessary to examine the swimmerets, the compound eyes, and
statocysts in relation to other organs, the account which immediately follows will be

Fig. 2. — Left second pereiopod of first larva of lobster, showing the primitive di-
vided form of the limb, with successive segments orpodomeres of protopodite {pro,
segments 1-2), and permanent inner branch or endopodite {End, 3-7). Ex, decid-
uous swimming branch or exopodite; Ep, epipodite or gill separator, with its gill
or podobranch {pbr).

NATURAL, HISTORY OF AMERICAN LOBSTER.

227

limited to the mouth parts and certain adaptations found in the walking legs, further
details being given in table 4. The history of the big claws is reserved for the following
chapter.

MOUTH PARTS.

In addition to labrum and metastoma, we designate as mouth parts the six pairs
of limbs which are concentrated about the mouth opening, and which are modified in
some degree for dealing with the food.

When the mandibles open, a conspicuous pink fold of fleshy tissue is revealed over-
hanging the median V-shaped fissure which is the lobster’s mouth (pi. xxxm). The
labrum is shield-shaped and compressed in a peculiar manner, being keeled above and
below on the middle line, with a thin free edge or border, so that it presents two upper
and two lower concave surfaces. The lower keel by fitting into the slit of the mouth
forms the upper bound of this opening as it passes into the dorsal wall of the esophagus;
the fissure is limited below by a soft, round papilla, from the sides of which spring
a bifurcated “lower lip,” or metastoma. The metastoma on either side consists of
a short strap-shaped blade fitting closely over the convex body of the mandible; it is
slightly ridged on the outer side and sparingly sprinkled with setae. Both labrum and
metastoma are richly supplied with organs which there is reason for regarding as sensory
buds. The sides of the mouth are formed by rounded swellings of the esophageal wall,
and are directly continuous with the metastoma below. When the jaws are closed
and their outer masticatory ridges meet on midline just over the mouth fissure, the
concave sides of the labrum fit into deep grooves which traverse the opposing man-
dibular surfaces, and since the groove of each mandible lies below the level of its cutting
ridge, it is impossible for the lobster to “bite its lip.” The V-shaped mouth described
leads through a very short esophagus directly to the large stomach sac. All of the
mouth parts which succeed the mandibles are thin and leaf-like up to the somite vn;
and all conform to their outer convex surfaces.

The six pairs of appendages which are concentrated about the mouth are abundantly
supplied with sense organs, and are charged with a variety of functions, the most obvious
of which are handing the food along to the mouth and mincing it in the course of passage;
that they further serve as organs of the chemical sense and of touch more or less com-
pletely is not to be doubted.

The mandibles of the adult lobster (fig. 7, pi. xxxv) are in form like hinged double
doors set in front of the mouth, and so hung to the cephalothorax of the animal that they
are capable of swinging only a little way in or out, or toward and away from the middle
line. The body of the mandible, which probably represents the coxa of a typical limb, is a
triangular convex bar, with a very oblique axis of articulation corresponding to its long
anterior side; the opening tendon of the abductor mandibuli muscle is inserted on the
anterior border, near the outer socket and exerts a pull sufficient to open the “door.”
The posterior border bears at a more favorable point near its middle, a long tendon,
from which fan out the fibers of the powerful adductor mandibuli muscle (see p. 242).
These muscles arise from the inner surface of the carapace on either side in front of the

228

bulletin of the bureau of fisheries.

cervical groove, and between two white tendon marks; when they work the “doors” are
swung to with force.

The masticatory surface of each jaw is represented by the short side of the triangle
which meets its fellow on the midline in front of the labrum. It is divided by a deep
groove into an outer cutting ridge, capped with a dense mass of yellow chitin, and a
lower and flatter surface, which appears to be available for mastication in but a slight
degree, if at all. The groove (g, fig. 7, pi. xxxv) not only protects the fleshy upper lip,
but gives play to a 3-jointed hairy palp, the two distal segments of which are sup-
posed to represent the endopodite. The palp is actuated by muscles lodged in the body
of the mandible itself, and possibly serves to direct food particles to the mouth, below
the level of the groove, and just beneath the tip of the labrum.

The lobster’s mandibles work essentially on the principle of the modern stone-
crushing machine; little or no lateral motion being possible in an animal with a hard
shell, they can serve only by repeated closing movements to divide and triturate the
larger particles of food, which, having resisted the preceding mouth parts, get pinched
between the meeting edges of the swinging “doors.”

The leaf-like first pair of maxillae, the smallest of the mouth parts (fig. 1, pi. xxxvi),
bear on their first segment a fringe of stiff hairs and on their second a comb of bristles,
which help to pass up the food or mince it when soft. The second maxilla serves chiefly
as a “bailer,” or rather as a fan for driving water out of the respiratory cavity in front.
(Fig. 2, pi. xxxvi.) This thin elastic plate lies nearly horizontal, the divided protopodite
and rudimentary endopodite closely fitting over the mandible and the conforming first
maxilla, and is formed by the fusion of an anterior exopodite and posterior epipodite,
the upper side of the former and lower side of the latter, when not in rythmic move-
ment, resting against the sides of the respiratory cavity. (For action of fan see p.
247.) The “masticatory ridges,” or setigerous coxa, and basis of the second maxilla
are partially cleft and distinctly separated by a superficial fold.

The first pair of maxillipeds (fig. 3, pi. xxxvi), except for one or two particulars, are
modified only in minor details from the condition seen in the first larva. The parts are all
rather soft, flattened, and curved to fit over the swelling mandibles and one another; the
setae of the meeting borders of the bases and coxae are soft and useless for mastication;
the exopodite lies against a shallow groove on the outer side of the two-jointed endo-
podite, the groove being marked by independent rows of setae and the branch pre-
senting a modified four-sided appearance. There is a long respiratory epipodite which
carries no gill, but a part of its outer border is folded or turned under so as to form
a trough, Jd in which plays the posterior blade of the “bailer,” or scaphognathite.

In the slender, outwardly swelling second maxilliped (fig. 4, pi. xxxvi) there is a
fused joint ( x ) between the ischium and reduced basis. The brushes of setae which fringe
the inner border of this compound segment and the long curved meros are all soft,
and on the small knob of the dactyl only do we find short stiff spines which can in any
way effectively react on the food in mastication. Both epipodite and podobranchia
are rudimentary.

NATURAL, HISTORY OF AMERICAN LOBSTER.

229

The third and last pair of maxillipeds are similarly curved and conform perfectly
to the typical limb, with the exception of a fused third joint between ischium and basis.
(Tig. 5, pi. xxxvi, x.) The three terminal segments of this appendage are flattened and,
as commonly carried, crooked downward upon the longer and more modified meros
and ischium. The latter podomeres are curved upward and outward, are three-sided,
and, like the former, bear double fringes of dense setae which are used, among other
purposes, as cleaning brushes (see p. 179). In place of the upper or inner fringe, how-
ever, the trihedral ischium is provided with a serrate crest, or row of about twenty
closely set “incisor” teeth. These tooth-like spines increase in size distally and end
over the joint in a strong curved fang. They work on the principle of an old-fashioned
nutcracker, but in this case with toothed jaws which are very effective in cutting the
coarser pieces of food delivered by the slender claw feet before they are passed on to
the smaller mouth parts. The first three segments of this limb are closely appressed
and quite flat where they meet on the midline, the coxa bearing two flat and hairy
spurs.

The third pair of maxillipeds are the only really effective “jaw feet,” and with
the mandibles the only appendages which play an important part in reducing the
food. Of the other mouth parts, the maxillae, especially the smaller first pair, and
the second maxillipeds without doubt help in the mincing process to which the food
is subjected, but their chief function, as in the first maxillipeds, is without doubt sen-
sory and for passing the food up to the mandibles. When the latter have finished
their work the “grist” is ready for the gastric mill.

THE SLENDER LEGS.

The ten thoracic legs, which are designated as the pereiopods in the higher Crus-
tacea, consist of the great chelipeds and four pairs of slender walking legs (pi. xxxvm),
the first two of which bear weak compound or double claws and the last two end in
simple dactyls.

The successive segments of these limbs move on hinges, a description of which
is given in chapter vii, and are actuated by opposing muscles in the typical way with
the exception of basis and ischium, in each of which a flexor is absent. (Fig. 1 , pi. xu.)
The basis has but one ventral or posterior extensor, with movement limited to a few
degrees of arc, and the ischium two posterior extensors inserted upon two tendons,
which are set close together on the margin of the shell at the opening of the meros.
Accordingly these limbs can not be flexed at the fourth joint. There are no fused
joints in the slender legs, which commonly break between basis and ischium, and are
regenerated from this plane.

Aside from their direct use in locomotion, the smaller pereiopods present a variety
of functions, the last pair possessing brushes for cleaning the abdomen (see p. 303),
and incidentally serve as picks to steady the animal as it crawls over the bottom. Far
more significant, however, are the clusters of sensory setae ( s . s., pi. xxxvm) arranged
in symmetrical rows on the last two segments of the slender legs. One can count a

230

BULLETIN OF THE BUREAU OF FISHERIES.

hundred brushes upon a single leg, and each brush contains from 50 to 100 setae, the
bundles themselves being gradually concentrated toward the tip. In other words,
each limb is furnished about its apex with from 5,000 to 10,000 sensory hairs, each
of which is supplied with at least one nerve element. With such sensitive feet the
lobster can feel its way securely at every step, whether by night or by day, as well
as test every object before handing it up to the mouth.

THE CENTRAL NERVOUS SYSTEM.

The nervous system, the coordinating and regulating mechanism of the body,
is composed of a complex series of distinct but closely related nerve elements, and
each element consists of a ganglion cell and one or more outgrowing processes, the
principal of which in certain cases is termed the nerve fiber. Three kinds of nerve
elements or neurons have been described, as follows: (1) Coordinating elements, which
lie wholly within the central system, the probable function of which is to coordinate the
action of its parts; (2) motor nerve elements, which consist of a ganglion cell in the
central mass and of a fiber process which passes out to a muscle or gland; and (3)
sensory elements, composed of specially modified cells of the outer layer of the skin and
of sensory fibers which enter the ganglia of the nervous system proper. Certain nerve
fibers which pass out to the skin or its immediate neighborhood end in close relation
with sensory cells and serve to convey impulses from them to the centers, while others
conduct motor impulses from the centers to the muscles or glands. The epidermic
cells of the skin may be regarded as the simplest sensory cells, or as the direct ancestors
of such, and all the specialized sense organs, such as the eye or statocyst, are essen-
tially modified patches or pockets of the outer skin layer.

The most primitive sense being that of touch, it is not surprising to find in an
animal like the lobster that virtually every part of the skin is capable of receiving and
distributing either tactile or chemical sense impressions. The proper sense organs,
however deep their final position in the skin or tissues, come into close relation with
the nerve fibers with which each is abundantly supplied. The sense organs are thus
a primary means by which any form of energy to which they are able to respond starts
a series of changes which are finally translated into what are known to us as sensations,
feelings, and other mental states.

The lobster has a nervous system of the relatively simple “ladder” or “chain” type
characteristic of the higher invertebrates (pi. xxxm), in which segmentation, begun
at a lower level in the animal scale, is the dominant character of its structure and
instinct the ruling method of its response. Its reflexes and instincts are very precise
and very stable, but not necessarily invariable, and, as we shall see at a later page,
the lobster even at the fourth stage is able to modify its actions in relation to experi-
ence and to form habits, and thus is gifted with a certain degree of what is usually
defined as intelligence in vertebrates. The uprights of the ladder are the long com-
missures of the chain, the rungs the transverse commissures, while the paired ganglia
for each somite lie at the junctions of these parts. In addition to this cord with the

NATURAL HISTORY OF AMERICAN LOBSTER.

231

appendicular and other nerves which spring from it, the lobster has certain stomato-
gastric nerves and ganglia which have been described as a rudimentary sympathetic
nervous system.

The brain or compound supra-esophageal ganglion (pi. xxxiii) is united, by means of
a ring-commissure which embraces the esophagus, to the chain of paired ganglia; this
traverses the mid-ventral portion of the body and is protected by an archway of the
internal skeleton in the thorax. The brain, which is thus the only ganglionic part of the
central nervous system dorsal to the alimentary tract, appears as a small whitish mass
at the base of the rostrum and between the stalks of the compound eyes. It gives
origin to the following paired nerves: (a) The large optic nerves, which terminate in
the optic ganglia and the compound eyes of the eyestalks; ( b ) the antennular nerves
supplying the first pair of antennae, and (c) antennal nerves which innervate chiefly
the second pair of antennae. The brain thus represents the fused ganglia of the first
three somites and is connected by esophageal commissures with the central cord.

The subesophageal ganglion, or first ventral link of the chain, lies below the
mouth and is composed of the ganglia of the mandibles, the maxillae, and the maxilli-
peds (segments iv-ix), more or less intimately fused together, the ganglia of the large
maxillipeds being nearly or quite independent.

Then follow five pairs of thoracic ganglia, which supply the legs and body wall,
and six abdominal ganglia, the last of which sends nerves into the terminal telson.
The longitudinal commissures between the twelfth and thirteenth somites diverge to
admit the sternal artery, which thereupon divides, one of its branches passing forward
and the other backward immediately under the nerve cord. (For nerves of cheliped,
see ch. vii, p. 265).

In the embryo and larva the nervous system is much more concentrated than in
the adult, and according to Allen (2) the thoracic ganglia are fused into one mass, which
is united by short commissures to the brain. The hinder part of the embryonic brain
is connected by a bridge commissure, which in the adult lies immediately behind the
esophagus.

The nervous system is composed of a central “ Punkt-Substanz ” or neuropile, which,
though granular in appearance, is in reality a felt work of fibers running in all directions,
and an outer covering of ganglion cells. According to Allen the posterior ganglia of
the chain give off two pairs of nerves, an anterior and posterior division; the anterior
nerve becomes a double branch in the adult lobster and supplies the limbs, while the
posterior division innervates the body wall.

THE PERIPHERAL STOMATO-GASTRIC SYSTEM.

In passing down the esophageal commissures, at a distance of about two-thirds of
their course from the brain, a small commissural ganglion is seen upon either side lying
against the wall of the esophagus. The delicate bridge commissure, which indirectly
unites both sides of the brain, lies immediately behind these small ganglia and toward
the lower side of the gullet, as already seen. Each commissural ganglion gives off two

232 bulletin of the bureau of fisheries.

nerves, a dorsal medio-lateral and a ventral or antero-lateral nerve of Huxley, which
send branches to a diffuse esophageal ganglion to be seen resting against the upper ante-
rior wall of the esophagus (pi. xxxm) ; from this ganglion, moreover, a median bundle,
the anterior visceral or azygos nerve, runs up the wall of the stomach sac, to end in a
minute gastric ganglion lying between the origins of the anterior gastric muscles. A
smaller anterior median nerve also joins the esophageal ganglion to the brain.

The stomato-gastric system thus consists of four peripheral ganglia, two of which
form a pair, and of peripheral nerves, which spring from them, in addition to a smaller
ganglion belonging to the labrum, to be mentioned presently. The dorsal or medio-
lateral nerve gives off two branches to the wall of the esophagus and bifurcates, a
dorsal division going to the esophageal ganglion and a ventral forming the labral
nerve, which has hitherto escaped notice. I have found that the two labral nerves end
in a small labral ganglion embedded in the fleshy mass of this organ; from it issue fibers
which presumably supply the sense organs of this part (see p. 237). The ventral nerve
gives off a small branch to the esophagus and divides, one section going to the eso-
phageal ganglion and the other passing to a plexus of fibers on the lower border of the
mouth; from this plexus a very diminutive median nerve is sent to the esophageal
ganglion.

Allen has traced with great skill the origin and course of the fibers in various nerves.
Many of these fibers, which have bipolar cells in their course and which terminate on
the walls of the esophagus, are possibly concerned with sensory cells.

SENSE ORGANS.

Special-sense organs, in so far as they are definitely known to exist in the lobster,
are (1) the eyes, and (2) the sensory hairs or setae, distributed over the body and
appendages, if we omit from this category those organs of ecjually wide distribution
which have the appearance of sensory buds and have received the general designation
of tegumental glands. The hairs embrace (a) tactile setae, which, though apparently
aimlessty scattered over the appendages, are really distributed in a definite manner,
including the setae of the statocysts, and (b) chemical setae, which abound on the
antennules and where for a long time they have been supposed to .possess an olfactory
function, as well as on the mouth parts, to which a gustatory sense has been ascribed,
and indeed upon the surface of virtually the whole body, where experiment seems to
prove that chemical sense organs of some sort exist.

EYES.

At the time of hatching, the lobster possesses three visual organs, a median Cyclo-
pean ocellus, a mere rudiment of the simple type of eye which proved useful to its ances-
tors and is still retained in the lower orders of Crustacea, and the paired lateral or
compound eyes. The latter, so conspicuous at all later stages of life, appear very early,
and at the close of the fourth week their black pigment can be detected as a dark crescent-
shaped line on either side of the head of the embryo. The eye is first disk shaped, then

NATURAL, HISTORY OF AMERICAN LOBSTER.

233

lobate, and finally stalked. In the first larva the stalks are immobile but very large,
being relatively four times longer than in the adult. From the fourth stage the faceted
eye is typically borne at the apex of a cylindrical movable stalk, which projects from
either side of the base of the rostrum. Each stalk (fig. 1, pi. xxxv) is capped with a
hemispherical surface, over which the cuticle has become modified into a thin flexible
membrane as transparent as glass. Through it is seen the black pigment which defines
the retinal area. This window-like cornea is interrupted by a process which juts in
like a peninsula from the opaque shell at a point where the field of vision seems to be
interrupted by the rostrum.

After the first larval stage the eyestalks recede somewhat until the lobster attains
a length of from to 3A inches, when their prominence is again very marked. In
short, they now assume the form and relative size of certain fossil Crustacea from which
the modern lobsters have probably descended.

The structure of the compound eye of the crustacean appears to be extremely
complicated, because it is composed of units repeated many thousands of times. As
was shown in 1889,® it is wholly derived by differential growth from a single plate of
columnar ectodermic cells, the optic disk, which arises very early in development on
either side in front of the future mouth and before the buds of the antennules are formed.

When the lobster’s eye is examined with a hand lens, its clear corneal membrane
has the appearance of a glass mosaic, composed of minute square disks of great uniformity
both in size and arrangement, especially in its central parts (fig. 2 and 3, pi. xxxv).
Each disk is the facet of an eyelet or ommatidium of the compound eye, and each sup-
plies a part of the mosaic image produced in vision when the light is sufficiently strong.
Each eyelet is developed from a cell cluster of the optic disk and this in turn from a
single columnar cell of the primary optic plate.

The axial part of the ommatidium consists of (1) the corneal lens secreted by 2
underlying cells, (2) the refractive cone derived from 4 cone cells, and (3) a long striated
and sensitive rod, the rhabdom, secreted and sheathed by 7 retinular cells, in addition
to 2 peripheral pigment cells which surround the crystalline cone; in this rod also a
nerve fiber terminates at the level of a basement membrane which divides the proper
eye from the complex optic ganglia, muscles, and other tissues contained in the rest of
the stalk. In ordinary daylight each eyelet is completely isolated by its sheath of
black pigment cells, all of which display ameboid movement, but which respond dif-
ferently to the intensity of the light stimulus.

In 1890, while working at the laboratory of the U. S. Fish Commission at Woods
Hole, Mass., I showed by experiments upon the prawn Palcemonetes vulgaris that when
this animal was placed in total darkness there was an immediate adjustment of the
pigment cells of the ommatidium, in consequence of which the whole eye became intensely
black and prominent, and that when returned to the light the eye began to lighten in
a few minutes and in a relatively short time assumed its normal daylight appearance.
It was shown that the blackening was due to a forward movement of processes of the

a The development of the compound eye of Alpheus. Zoologischer Anzeiger, bd. xn, p. 164-169, fig. 1-5. Leipzig, 1889.

234

BULLETIN OF THE BUREAU OF FISHERIES.

distal pigment cells. One shrimp was kept in darkness 38 days, but the change was
the same whether the interval was one of a few hours or weeks.® The true significance
of this response was clearly established by Exner in his remarkable work on the phy-
siology of faceted eyes in insects and crabs, published in 1891.* 6 It was shown that the
distal and proximal pigment cells or the “iris” and “retina” pigment moved in opposite
directions in response to waning light, the former in its “night position” moving up to
the cornea and leaving the refractive cone exposed and the latter crowding down upon
the basement membrane, thus exposing the sensitive tip of the rhabdom. In the
“day position” the converse movement takes place when the eyelet is completely
isolated, and only those rays which are parallel to its long axis can enter and reach the
rhabdom. c When the pigment screens are separated and drawn wide apart at night, on
the other hand, light rays of any angle can pass freely from one ommatidium to another
to be refracted by the exposed cones upon the upper ends of the exposed sensitive rods.
The response is thus an adjustment to economize light, though at the expense of clear-
ness of image. At dusk the lobster can presumably distinguish moving objects, but
only dimly, since the eye at this time can produce no clear mosaic images.

The compound eye of the house fly is said to have about 4,000 facets, that of a
dragon fly 20,000, while in a 12-inch lobster I estimated the number to be 14,000.
Assuming that the ommatidia are equally well isolated and equally sensitive in each
case, the relative efficiency of mosaic vision in insect and crustacean would be proportional
to the number of facets. Upon this showing the lobster has a rather poor eye when we
consider the unfavorable medium in which its visual powers must be exercised. The
image produced by this organ, as Exner showed by a photograph made through the
medium of the faceted insect eye itself, is single and upright ; sight is attended by
great loss of light, and must be very imperfect except for short distances and when the
animal is moving in shallow water strongly lighted. The fact that the lobster is most
active at night, that it is abundantly supplied with tactile organs for feeling its way
about, and that the greater part of its life is spent at depths where clear vision is
impossible for lack of light, show us further that its visual organs can play but a subor-
dinate part in the activities of its daily life.

SENSORY HAIRS.

Certainly the most numerous and probably the most important sense organs of
crustaceans generally are the sensory hairs or setse, which are all of epidermic origin.
Each hair consists of a hollow, conical, or nearly cylindrical shaft of chitin, continuous
with the general cuticular basis of the shell, and is associated with one or more sensory
nerve elements connected with the central nervous system.

a Memoirs of the National Academy of Sciences, vol. v, 4th mem., p. 454. Washington, 1893.

& Exner, Sigm. Die Physiologie der facettierten Augen von Krebsen und Insecten. Leipzig, Wien, 1891.
cIt has been found by Congdon that increased temperatures cause movements in the pigment cells, which are probably of
a non-adaptive character and are reverse in direction to those caused by light. See Congdon. E. D : The effect of temperature
on the migration of the retinal pigment in decapod crustaceans. Journal of Experimental Zoology, vol. iv, p. 539-548. 1897.

NATURAL HISTORY OF AMERICAN LOBSTER.

235

The exact analysis of the sense organs of the higher Crustacea is still a vexed problem,
and the literature of the subject far from satisfactory.® In the description to be given
I shall follow in the main the account of Prentiss (217), who worked upon the common
prawns, Palcemonetes and Crangon vulgaris, with which the lobster undoubtedly agrees
in these particulars. The sensory bristles of decapods have been found to conform to
two types: (x) The tactile, and (2) the olfactory, or better, the chemical setae which
are sensitive to chemical stimuli. The former have straight, long, and often plume-like
shafts, and at the base of each a spherical enlargement is formed, which, owing to its
thin wall, permits the hair to swing freely as upon a joint. Bristles of this type occur
all over the body and appendages, and the “auditory hairs’’ of what has been called
the “ear-sac” or otocyst (fig. 2 and 4, pi. xxxv) are of this form. According to Prentiss,
each is supplied with a single nerve element. The “olfactory” or “chemical” bristles are
shorter, more cylindrical, or less tapering chitinous tubes, with no marked basal swelling.
Their tips are either perforated or possess so thin a wall as to permit the ready diffusion
of chemical substances from the water to the inside of the shaft. Each bristle is supplied
with a cluster of nerve elements, which may be very numerous, their fibers ending free
in the shaft, but not penetrating to its apex. Such setae are apparently more highly
specialized and are restricted to the small antennae, where they are called olfactory
hairs, or to the mouth parts, where they are often spoken of as gustatory bristles, though
it is probable that their functions are the same wherever found.

RELATION OF THE SETAJ TO HATCHING AND TO MOLTING.

The way in which these sensory hairs are formed and renewed at each molt is very
interesting. The subject has been investigated by a number of naturalists, but in the
brief account which follows we shall depend mainly upon the observations of Prentiss.
Each hair is secreted by a number of matrix cells which send their processes up into its
shaft. In preparation for the molt the protoplasm recedes from the shaft of the hair
and its matrix cells sink into the tissues and with other cells form a “papilla” around
the nerve fiber and begin to secrete a new hair. This condition lasts for a long time in
an adult animal, but for a few days only in the larva, which often passes several molts in
the course of a week. The cuticle which is to form the new shell and hair is secreted
under the old which is soon to be cast off, but the new hair is invaginated, so that below
the level of the skin its wall is double, while its tip only projects into the hollow shaft of
the old hair above it. The walls of the double hair tube are thus continuous with each
other and with the general cuticle which is to form the new shell.

In this condition the hairs may be compared to the fingers of a glove which have
been pushed in or telescoped, so that their tips only project from the surface. When
the lobster is ready to molt every new hair on its body is in this condition. Now at
each molt we always find between the old and new cuticle a sticky, homogeneous
substance which adheres both to the old shell and to the tips of the new hairs. Molting

a For a review of this subject, see Bell: The reactions of crayfish to chemical stimuli. Journal Comparative Neurology and
Psychology, vol. xvi, p. 299-326. 1906.

236

BULLETIN OF THE BUREAU OF FISHERIES.

thus becomes a means of drawing out or evaginating every microscopical hail of the
newly-formed armor.

This adjustment is even more complicated in the young lobster about to hatch.
Its “swaddling clothes” are so pinned together that all come off as one piece; the animal
hatches and molts at the same time. The outer egg membrane splits lengthwise like the
skin of a pea; it is glued in certain places to the inner membrane or true egg shell; this
adheres to the outer deciduous cuticle, which in turn sticks at innumerable points to the
hairs; by the time the animal has kicked off its covers it is thus ready to swim, for
every hair is drawn out to its full length.

In hatching the eggs of lobsters by artificial means in jars or boxes, this delicate
adjustment often fails at one point, and the little animal is doomed. The egg membranes
fail to stick, and thus to pull out the swimming hairs, so that the young lobster is hatched
in a helpless condition. It struggles in vain, a prisoner inside of its own skin, which it
is unable to shed.

Blood pressure is another factor which enters into this important process of evagi-
nating the setae, and in all adult lobsters withdrawal of the blood from the great claws is
an essential condition of the molt. As a consequence, when the animal escapes from the
old shell, the hair clusters on the deformed plastic flesh of the great claws are scarcely
visible, while they are prominent in other parts. With returning blood pressure the
hairs of the toothed claw are fully evaginated. It seems evident that when once the
shell has become hard no further evagination of the hairs is possible.

From the method of formation of new hairs it follows that at each molt, as Prentiss
has shown, the nerve fibers lose their connection with the old hairs and enter into
relations with the new ones.

TOUCH, TASTE, AND SMELL.

As long ago as 1868 Lemoine (779) suggested that the senses of taste and smell in
higher Crustacea might be blended with that of touch, and while many able workers
have since attacked this problem and produced far better results, we are still unable
to speak with much exactness upon the subject. As I have shown by earlier experiments,
nearly every part of the lobster’s body is subject to tactile or chemical stimulation, and
must therefore be supplied with sense organs of some sort. (See 149, p. 129.) We found
that the parts most richly supplied with setae, with the exception to be noted below, were
most sensitive, and it seemed evident that all the soft setae, whether fringing and pro-
tective or not, were sensory. It was further observed that the greater sensitiveness
was lodged in the antennules, and especially in their outer whips, which bear the peculiar
club-shaped setae, the antennae, the tips of the slender legs, and in younger animals, at
least, in the fingers of the big claws. Stimulation with various gases and liquids, injected
with a pipette upon a given part, gave more or less prompt reflexes either in the limb
itself or in the appendages nearest the part affected. If any stimulus, whether electrical,
tactile, or chemical, be applied to the right second maxilla or right first maxilliped,
vigorous chewing movements are immediately started in the affected appendage of that
side, and may spread to the side opposite.

NATURAL HISTORY OF AMERICAN LOBSTER.

237

The swimmerets of the lobster were also proved to be quite sensitive under most
conditions, as well as the thoracic sterna, the wings of the seminal receptacle of the
female, and even the hard carapace, which was nearly as responsive to weak acids as
is the soft skin of the frog, and the scratching movements made by the legs in the direc-
tion of the stimulated part are essentially the same in each case. We concluded that
the sense organs were the setae, reenforced by sensory buds, which lie in the tissues
beneath the hard shell, but open upon it by capillary ducts. For other reasons these
perplexing structures were given the name of tegumental glands. We have found no
reason to alter this conclusion, and can still point to the upper lip as a supporting case.
The labrum while possessing no true setse is highly responsive to chemical stimuli, and is
full of the organs in question, which open by ducts all over it in the lobster, but are
most abundant on the under concave surfaces, to which a greater sensitiveness was
attributed in the crayfish by Lemoine; here the ducts are clustered in large sieve-like
plates bearing 60 to 70 holes each. We have further shown (see p. 232) that the labrum
is not only well supplied with nerves, but possesses an independent ganglion of itsown.
That these labral organs are not glandular in function might be also indicated by the
fact that the upper lip is always clean in the lobster, and free from anything suggesting
a glandular secretion.

Experiments on the crayfish by Bell and others have shown conditions essentially
similar in most respects. In getting food, sight plays little part, the blinded crab or
crayfish going unerringly to the bait. This is certainly true of the lobster, as the
experience of fishermen amply proves. Apparently through their chemical sense organs,
for we do not seem warranted in using either the word “smell” or “taste,” they become
aware of the presence of food, and are attracted to it, while in the crayfish accuracy in
the localization and in the seizure of the food seems to be secured through the medium
of touch.

Bethe, who performed some strking experiments with the common green crab,
Carcinus mcenas, found that the chemical reaction was the most important in its search
for food.

The mouth parts, says Bell, in summarizing Bethe ’s results, seem to be more sensitive to chemical
stimulation than the antennre or the antennules, since the animals react when the latter are removed.
The threshold of chemical stimulation is extremely low, for the animals react most vigorously to the
trail left in the water by a finger that has been in contact with meat, and greedily devour filter paper
which has barely touched meat, but to really clean filter paper they pay no attention.

Holmes and Homutha have repeated Bell’s experiments on the crayfish and tested
its reactions to chemical stimuli after removal of the antennules and antennae, and
after destruction of the brain and a section of the ventral nerve-chain. They confirmed
the old opinion that the olfactory sense was lodged chiefly in the outer branches of
the antennules, but found it exercised in a lesser degree by the antennae, the mouth
parts, great chelipeds, and the slender legs. Destruction of the brain or nerve cord
tended if anything to slow down the reactions, but did not put an end to response.

a Holmes, *5. J., and Homuth, E. S.: The seat of smell in the crayfish. Biological Bulletin, vol. xvm, p. 155-160. Boston,
1910.

238

bulletin of the bureau of fisheries.

The lobster feels its way in the dark or gropes about in twilight by the aid of the
sensory hairs with which it is abundantly supplied. From 50,000 to 100,000 of these
organs are present on the big claws and slender legs alone. In most cases we do not
find it possible to discriminate between hairs which are solely tactile or for the chemical
sense alone. The lobster finds its way, however, to the fisherman’s baited trap after dark
or in dim light by the aid of all those setae which respond to the chemical stimulus, and
chiefly no doubt by those on the anterior appendages, the hairs which project from
the lower sides of the outer whips of the antennules being probably the most sensitive.
Fine particles of the bait which diffuse through the water from all sides of the trap, or
are carried by currents, furnish the stimulus which draws this animal to their source.

BALANCING ORGANS OR STATOCYSTS.

It is commonly observed that while a living fish swims with its body erect and poised,
a dead one floats on its side, and that the former position is one of unstable, and the
latter one of relatively stable equilibrium. The upright unstable position is maintained
in life by compensating movements which are automatically called into play by aid
of special sensory bodies called static organs. This is true of the lobster, and of all
animals which carry themselves upright, in opposition to the force of gravity.

There is now considerable evidence to show that what were formerly regarded as
true “otocysts,” or ear sacs, in the basal segments of the first pair of antennae, are
static rather than auditory in function, and accordingly they have been more appro-
priately called statocysts or organs of equilibration. The sac of either side (fig. 2)
fills nearly the entire segment, and is open to the outside by a fine pore barely large
enough to allow a minute grain of sand to pass, or to admit the point of a pin. The
membrane overlying this sac is thin and taut (fig. 4, pi. xxxv, mm.) ; long setae
encircle it, and also surround the mouth of the sac.

The sac originates as a shallow pit of the skin, sinks into the tissues, becomes hori-
zontally flattened, and remains attached to the cuticle along its transverse front, the
opening being gradually constricted to a minute pore on the inner side of the thin
membrane. Upon dissection and examination of the sac from within, we see on its
floor a semicircular or horseshoe-shaped sensory ridge (s. r., fig. 3), studded with a
median row of about 75 plume-like hairs and four times as many shorter setae arranged
on either side or crowded about its mouth. Three hundred and seventy-five hairs
were present in a single case examined, but the number may be considerably greater.
Some of the hairs have bent shafts; some are thread-like, and scattered among them
and often glued to their tips are numerous fine sand grains, the “ear-stones” or otoliths,
as they have been called. In one of the sacs examined there were several hundred
grains, ranging from one-fortieth to one-six-hundredth inch in diameter, the smaller
being far too minute to be picked up with the points of the finest forceps. Each hair
of the sac is supplied with a nerve-element, and as Prentiss has shown, with but a single
one, as is the case with all tactile setae.

NATURAL HISTORY OF AMERICAN LOBSTER.

239

From the foregoing account it will be seen that in the water-filled sacs just described,
with their rich supply of sensory hairs, many of which, having little weights in the form
of sand grains glued to their tips, and all being subject to the impact of free particles
with the least displacement of the body, we have what would seem to be an admirable
apparatus for enabling the animal to carry itself erect in walking or swimming. Any
swaying of the whole body would sway the little hairs, or rattle the sand over them,
and the stimulus thus given, would act as a sign to which the nervous system of the
animal could respond in an adaptive and useful manner.

The study of development throws some light on the probable use of these peculiar
sense organs. As shown by my earlier studies but first carefully worked out with
histological definiteness by Prentiss, the sacs are developed in the free-swimming stages.
They are barely visible as shallow depressions in the second and third larvae, but in the
fourth stage sensory hairs and sand grains are present, and closure of the sacs, which
has now begun, is gradually effected with each successive molt. As Prentiss has shown,
this “sudden leap” in the appear-
ance of the sacs at the fourth stage
is probably related to the abrupt
change in form and method of
swimming exhibited at the fourth
molt.

Every one who has watched
the swimming movements of the
young lobsters up to the fourth
stage (fig. 34 and 42) has noticed
how unsteady they become when-
ever the water is in the least de-
gree disturbed. In ordinary swim-
ming, when their equilibrium is not
upset, the thorax is horizontal
inclined downward, but at best they are very unstable, and frequently pitch and
reel to and fro, swimming now on their backs, now with their heads directed up
or down. (See fig. 40.) It should be added, however, that under certain conditions,
as in dull light, the young larva, as Hadley observes ( iji ), swims with grace and pre-
cision, and there is no doubt that the eyes act before the statocysts as organs of
orientation.

At the fourth stage (pi. xxxi) the little animals uniformly bear themselves erect like an
adult and move about with great speed and definiteness. Prentiss has pointed out that
when the young at this stage are unable to get sand for the statocysts, their movements
again become uncertain, like those of an adult animal from which the sac has been
removed. It is thus evident that while other organs, such as the eyes and antennae,
may help a crustacean to maintain its erect attitude, the sacs are indispensable for this
purpose, at least after the larval stages.

Fig. 3. — Sectional view of antennal segment to show statocyst, with needle
inserted in pore at surface and pointed to sensory ridge, 5 r.

and the abdomen bent; in rising the head is

240

bulletin of the bureau of fisheries.

It seems to be established that the supposed response of aquatic animals to atmos-
pheric sounds of ordinary intensity is a myth, for sound waves propagated in air are
almost totally reflected from the surface of water, but since sound vibrations are trans-
mitted by water it does not follow that aquatic animals are necessarily deaf. An animal
so abundantly supplied with tactile organs as a lobster has little need of ears, since sounds
transmitted through the water would be perceived or felt by means of the sensory hairs.
“The range of the average auditory organ in mammals,’’ to quote from the work of
Prentiss, referred to above, “ is from 30 to 16,000 vibrations per second; waves of less
than thirty vibrations per second do not usually produce auditory sensations, but are
appreciable to the tactile sense. It is important to note that decapods respond most
vigorously to low notes, and not at all to high notes or sounds produced by very rapid
vibrations. This fact would seem to be good evidence that the vibrations imparted to
the water and perceived by decapods correspond to those which produce tactile rather
than auditory sensations in vertebrates.’’ It has been noticed that the so-called “audi-
tory” hairs of certain crustaceans will vibrate to different musical notes, as will the hairs
on the back of one’s hand or the strings of a violin, but they are not auditory, as
Prentiss remarks.

It is only natural to find that the senses of touch and hearing grade into each other,
and in either case it is the effect of a vibration which is perceived. While it is a matter of
convention how these sensations are described, it is evident that an aquatic animal like
the lobster has no organ strictly comparable to a vertebrate ear or even to the auditory
or chordotonal organ of insects, and that if possessed of such an instrument it would have
little occasion to use it. The basal segments of the large antennae of Palinurus possess
a peculiar structure often called a “stridulating organ,” but nothing seems to be known
of the real uses which it serves. (See p. 160.)

To return for a moment to the sacs, which have the form of a narrow-necked bottle,
and are carried in the antennulae, how do the sand grains find their way through their
minute openings, guarded with hairs ? Professor Brooks has seen the megalops larva of the
crab, Callinectes , pick up the grains and place them in the sac with its claws. As an
illustration of animal instinct, this is truly remarkable, for it is peculiar to the larvae alone,
the adult crab having no sand grains or otoliths of any kind in its sacs. The lobster at
the fourth stage nearly corresponds to the crab megalops, but it has never been seen to
behave in this maimer. Whatever method the young may adopt to replenish their stock
of sand after each molt, it is evident from the microscopical proportions of the grains
that adults behave in a different manner. The animal in all probability thrusts its head
in the sand, while the smaller grains, selected by the one opening of the “strainer,” grad-
ally sift into the sac by the force of gravity. The spiny lobster (Palinurus) , which also
keeps its antennal sacs well supplied with sand, has no claws with which to pick up any-
thing, and must have recourse to a similar method. In reference to this peculiar need
of the animal, it is interesting to notice that molting lobsters often burrow in the sand,
where they remain for some time after casting the shell.

NATURAL HISTORY OF AMERICAN LOBSTER.

24I

THE MUSCLES.

The muscles of the lobster’s body are of two kinds, the striped or striated and the non-
striated, distinguished in higher animals as the voluntary and involuntary muscles. The
involuntary muscular tissue is inconsiderable in quantity, excepting the “fine meat” at
the tips of the claws, being mainly confined to the walls of the alimentary canal, the
blood vessels, and sexual organs. The heart and powerful skeletal muscles are composed
of distinctly striated fibers.

The skeletal muscles, of which the large adductor of the mandibles is a good example,
are attached to the hard shell on the one hand, and to tendinous ingrowths of the softer
cuticle on the other. Just how the union with the shell is effected is a somewhat vexed
question. In the first larval stage of the lobster the prominent muscle just referred
to is distinctly striated up to the basement membrane. (Fig. 2, pi. xlvi, bm.) At this
level its fibrillse are directly continuous with attaching fibers within the cells of the epi-
dermis; the basement membrane is accordingly penetrated at this point. Examination
of earlier embryonic stages shows essentially the same conditions. The epidermis of
the shell in the area of attachment ( fb . ep.) is modified in a characteristic manner; its
cells are columnar and elongated, and their cytoplasm develops fibers which appear to
fuse with those of the muscle-fibrillae ; moreover, their nuclei are eventually reduced
and spindle-shaped, though this was not the case in the specimen figured. The base-
ment membrane in this region is a distinct cuticular sheet, to which blood cells and
other elements (ms.) presumably of mesoblastic origin also attach themselves, with long
axes parallel with the surface, thus making a distinct lamella. The horizontally placed
lamellar cells can be detected beneath the modified epiblast, where the cuticular portion
of the membrane appears to be reduced or absent. In some cases the epiblastic fibrils
brush out perceptibly at their periphery against a concavo-convex layer of chitin, upon
which the outermost stratum of the shell is molded. Since the clearer inner chitinous
layer frequently peels off in preparations, it may represent a renewal of the shell at this
point previous to molting.

In his study of regenerating limbs in the lobster, Emmel (97) has found that the
striated muscles are regenerated from ectoderm, and that the outer ends of the myo-
fibrillseare differentiated as tensile elements, which pass between the proper epidermic cells,
are frequently spread out in branches, and are fused directly to the chitin of the shell.

The muscles of the tail, which form a great part of the edible flesh of the lobster (pi.
xxxiii) consist of two paired masses, the dorsal extensors, by the contraction of which
the abdomen is straightened, and a much larger pair of ventral muscles, mainly flexor in
function, which form the principal source of power for locomotion. As we have seen, the
segments of the shell in this region are united by flexible membrane, and move over artic-
ular surfaces as well as upon double hinges of the typical ball-and-socket form, and that
the parallel and horizontal arrangement of their articular axes limits the flexion of the
tail to the vertical plane. The ventral muscles are very complex, being composed of
external bundles attached to the side walls of successive segments, and of interlooping or
enveloping strands, which are fixed to the lower or sternal parts of the skeleton. A

48299° — Bull. 29 — 11 16

242

BULLETIN OF THE BUREAU OF FISHERIES.

twisted rope-like mass is thus formed, the forward strands of which are attached to the
linkwork of hard tendons in the thorax. There are also in the thorax, rotator abdom-
inis, ventral thoracico-abdominis and tergo-epimeral muscles, as well as flexors of the
telson and tail fan in the abdomen.

The weaker dorsal muscles (pi. xxxm) form a pair of segmented strands overlying the
Alimentary canal and dorsal blood vessel. They are inserted into the anterior border
of each abdominal somite and diverge as extensor abdominis muscles in front, where
they are attached to the walls of the thorax below the cervical groove. When the
(ventral muscles suddenly contract at the command of the nervous system, the combined
pulls on successive joints bring the tail with expanded tail fan quickly and violently
down upon the thorax, and the animal shoots backward through the water. By the
contraction of the weaker extensor muscles the body is again brought into a horizontal
position, and ready for another downward stroke. Raising the abdomen tends to send
ithe animal forward, but owing to the obliquity and slowness of the stroke after closure
of the tail fan the speed is but little checked. The muscular equipment of the great
claws and legs are described in chapter vn.

Two prominent light spots are conspicuous on either side of the carapace of an
adult lobster, one at a point about an inch behind the base of the large “feelers,” and
the other about as far behind the first, close to the irregular depression known as the
cervical groove. (See p. 220.) The first, which is large and very conspicuous at the
sixth stage, when the animal is barely five-eighths inch long, is the mark of a straight
rod-like tendon which binds the carapace firmly to the internal skeleton below. The
latter was without doubt originally a tendon-mark also, but in place of a distinct tendon,
short muscle fibers issue from its margin, and from the groove in front, to be attached
to the wall of the gill chamber. The scar-like impression conforming to the groove and
immediately in front of it marks the attachment to the shell of the posterior suspensory
muscles of the stomach sac. The powerful adductor of the jaws, by the contraction of
which their cutting surfaces are brought to bear on the food, divides to give passage to
this gastric muscle, one section of which is attached to the carapace in front of the
groove, and the other just behind it on the endotergites, which as stated above are
tendinous ingrowths from the fold itself. The anterior gastric muscles are inserted on
the procephalic plates.

Some fourteen pairs of extrinsic and intrinsic gastric muscles have been described
by Williams (279). These serve either to suspend the stomach sac to the inner wall of
the carapace (anterior gastric, anterior dilators, and posterior and lateral gastrics) or to
move its nicely articulated framework, bring the food to mill, work the grinding teeth,
and to effect in some measure the sorting and straining of the comminuted food particles.

THE BLOOD AND ORGANS OF CIRCULATION.

The blood of the lobster when freshly drawn is quite colorless, leucocytes or white
blood cells being the only corpuscles present, but after exposure to the air for a few
minutes it becomes tinged with blue, and thickens or coagulates. The bluish color is
imparted by a respiratory pigment called haemocyanin, which like the haemoglobin of

NATURAL HISTORY OF AMERICAN LOBSTER.

243

red blood becomes deeper in color as it takes up oxygen. The bluish tint of the larval
lobster is probably due in part to the hsemocyanin of its blood. The blood is also
regarded as the bearer of other pigments, the lipochromogens, which are probably
elaborated in the digestive gland, transmitted by the blood, and laid down in the pig-
ment cells and the shell.

The heart begins to pulsate rythmically when the lobster is an embryo, between
4 and 5 weeks old,“ at a time when the black pigment spots of the compound eyes have
begun to show, but when the nervous system has been only roughly blocked out and
long before any nerves are developed. The heart, although later brought under nervous
subjection and control, is at first quite automatic and independent in its movements.

The circulatory system of the lobster (see pi. xxxm) consists (1) of a muscular heart
for driving the blood, (2) of arteries or definite channels for conveying it to the tissues,
and (3) a system of irregular channels called sinuses or lacunae, besides certain well
defined vessels, the veins for leading it back to the pericardial chamber and heart.
The arteries end in microscopic capillaries which open directly into the lacunar system.

The freshly aerated blood of the lobster is driven from the gills to the pericardial
sinus, enters the heart through the ostia, is pumped thence by the rhythmical contrac-
tions of its walls into the arteries, and by their subdivisions is distributed over the
entire body. Having performed its physiological work of giving up to the tissue cells
dissolved oxygen and food materials, and having received from them carbon dioxide
and other waste products, it returns by the lacunar system to the large ventral sinus,
which surrounds the ventral nerve-chain; thence the venous blood is driven to the gills,
where aeration is effected by the absorption of oxygen from the fresh streams of sea
water in which they are constantly bathed. More simply expressed, the path traversed
is heart, body, gills, heart. The gills are placed in the returning blood stream, so
that the vessels which both supply the gills with venous blood (afferent branchial ves-
sels) and which conduct arterial blood from the gills to the heart (efferent branchial
and branchio-cardiac vessels) may be described as veins.

THE HEART.

Examining the heart more closely, it appears as a boat-shaped or somewhat hexag-
onal body, rounded below, flattened above, and broader in front. It is pierced
by three pairs of openings, the dorsal, ventral, and lateral ostia, which admit blood
from the pericardial sinus. Each ostium is provided with valves which open inward,
so that the blood once admitted to the heart can not be regurgitated to the sinus.

The heart gives off a series of arteries, five in front and two behind; these are also
supplied with valves (or at least in the largest of them, the sternal), so that the heart
can empty only into the arteries, while it can fill only from the sinus.

THE PERICARDIAL SINUS.

The chamber in which the heart is suspended, called the pericardial sinus, lies at
the extreme upper and hinder part of the carapace; it is lined with connective tissue

a The beating of the embryo lobster's heart has been noted in winter (December 14) at 100 times per minute.

244

BULLETIN OF THE BUREAU OF FISHERIES.

and muscle fibers,® and has an arched roof and floor, with sloping sides. This chamber
lies close to the back, so that if the shell is perforated anywhere in the cardiac area
the animal will quickly bleed to death. The convex floor of the sinus covers the
sexual organs and the digestive gland, while at the sides only the thin shell of the
body wall (inner epimeral surface) separates the sinus from the upper part of the
branchial cavity. Moreover, the extensor muscles of the tail virtually pass through
the sinus and are inclosed between its sides and floor.

The heart beats rythmically and heat accelerates its action. Plateau (214) found
that the isolated lobster’s heart, when placed in a moist chamber, would beat for nearly
an hour; according to this investigator the movements of the decapod heart are governed
as follows: (1) By a cardiac nerve which arises in the stomato-gastric ganglion and
ends in the heart muscle; (2) by ganglion cells within the tissue of the heart itself, by
means of which its automatic movements are maintained, and (3) by depressor nerve
fibers which moderate the heart’s action, but the real courses of which are not known.
The brain is found to have no direct influence upon the action of the heart.

THE ARTERIES.

Of the five anterior arteries the ophthalmic or cephalic runs along the middle
line just beneath the shell, and makes straight for the brain, which it supplies,
together with the eye stalks (upper side), giving off a few twigs to the stomach sac in its
course. The paired antennal arteries issue from the side of the ophthalmic, and in passing
forward along the surface of the gastric glands they give off numerous small branches
to the following organs: The glands themselves, the gastric muscles and walls of the
stomach, the sexual organs, the thoracic muscles, and the body wall, or the integument
of the carapace and the inner epimeral wall of the branchial cavity; finally the same
vessel sends twigs into the eyestalk, the antennule, the adductor mandibuli muscles, the
antenna, and the green gland which lies at its base. The paired hepatic arteries supply
the gastric glands. Both ophthalmic and antennary arteries are subject to considerable
variation in both the lobster and crayfish. (See fig. 1, pi. xliv.)

Two arteries issue from the hinder end of the heart, where it swells into a bulb,
namely the sternal artery, which passes straight down and penetrates the nerve cord, and
the superior abdominal artery, which supplies the greater part of the tail. The sternal
gives off twigs to the sexual ducts before it swerves to pass the intestine, and entering
the ring formed by the long commissures between the fourth and fifth ganglia of the
ventral chain (somites xii and xm), gains the ventral side, where it divides or gives
off a posterior branch, the inferior abdominal artery, which supplies a small part of the
ventral surface of the abdomen, but none of the appendages. The main branch of the
sternal, the inferior thoracic artery, runs forward under the nervous system, and sup-
plies the slender legs, the great forceps, and the mouth parts.

a According to Dogiel (72), the pericardium also contains blood vessels, which can be injected from the superior abdominal
artery, as well as nerves supplied by a trunk (nerve of Dogiel) which is given off from the ganglion of somite xn. The valves of
the heart are further regarded as properly sphincters, rather than of the bilabial or semilunar form. On the other hand the sternal
artery, of which the superior abdominal may be considered a branch, is provided with true valves of the bilabial type.

NATURAL, HISTORY OF AMERICAN LOBSTER.

245

ARTERIAL SUPPLY OF THE SWIMMERETS.

The dorsal or superior abdominal artery passes backward just above the intestine
and gives off six pairs of segmental lateral vessels, which, besides supplying the intestine
itself, send arterial blood into the great muscles of the tail, the posterior lobes of the
gastric glands, and the sexual organs. To complete the statement, however, it must
be added that the main branches of the lateral segmental vessels are curiously continued
around the sides of the body to the swimmerets or pleopods, which they feed with
arterial blood.®

The swimmerets have been invariably described as receiving their blood from the
inferior abdominal artery, both in the lobster and crayfish, an error which may have
arisen in the first instance from failure to inject the vessels or from inference, proba-
bility favoring the inferior vessel, on the principle that organs as a rule draw their blood
supply from the nearest source. The error, started in some such way, has escaped the
scrutiny of such keen observers as Professors Huxley, T. J. Parker, and Plowes, and is to
be found in all the text-books and literature dealing with these forms. It can be seen,
however, without recourse to much dissection, that the inferior abdominal artery is
too diminutive and passes altogether too small a quantity of blood to supply the
swimmerets, which are the most active of all the appendages, excepting only the
respiratory plate or “bailer” of the second rtiaxilla.

The superior abdominal artery divides at the hinder border of the fifth somite
into two branches, which embrace the intestine where it gives off a short caecum on its
upper side, and which run backward and diverge to supply the sixth somite and tail fan.

The principal artery of the big claw (pi. xl) traverses the lower side of the limb
and gives off numerous branches to the muscles of the segments. In the fifth podomere
it sends off a shoot which enters the big claw, passes to the abductor muscle along the
inner border of the big tendon, and ends in the fine meat of the dactyl. The main
artery, upon entering the claw, again divides, giving rise to four branches, three of
which supply the big adductor muscle and the fine meat of the propodus, while the other
passes to the adductor muscle and divides, sending a branch to both dactyl and pro-
podus. The division to the dactyl is united by a cross branch to the vessel which
supplies the abductor and enters the propodus from the fifth joint. In the index and
dactyl the arteries ramify in tree fashion, and apparently break up into a lacunar
system of irregular spaces in the fine meat. From this situation the blood returns by
a large irregular channel and enters the sternal sinus, whence it reaches the gills.

It has been shown by Fmmel (97) that as the returning sinus of the great cheliped
passes the ischium or third podomere it is divided into two channels by a septum of
connective tissue. These dorsal and ventral sinuses, moreover, possess valves which
originate as folds from the septum and become operative to staunch the flow of blood
from the breaking joint the moment a claw is shot off (see p. 282).

a I am indebted to Prof. Carl B. James for first directing my attention to this fact, which must have been noticed by other
teachers in the laboratory.

246

bulletin of the bureau of fisheries.

THE GILLS.

The adult lobster is provided with 20 pairs of gills, 1 of which, belonging to the second
pair of maxillipeds, is rudimentary. Of these, 6 are podobranchiae, 10 arthrobranchiae,
and 4 pleurobranchiae, distributed according to the following table:

Table 5. — Branchial Formula of the Lobster.

Thoracic segments and appendages.

Podo-

branchiae.

Arthrobranchiae.

Pleuro-

branchiae.

Totals.

Anterior.

Posterior.

VII, first maxilliped

0 (ep.).

VIII, second maxilliped

i rud. (ep.).

IX, third maxilliped

1 (ep.).

3 (ep.).

X, first pereiopod

1 (ep.).

3 (ep.).

XI. second pereiopod

1 (ep.).

4 (ep.).

XII, third pereiopod

1 (ep.).

4 (ep.).

XIII, fourth pereiopod

x (ep.).

4 (ep.).

XIV, fifth pereiopod

Total

6 (ep.).

20 (1 rud.).

ep.= epipodite. rud=rudimentary.

The first larva has no rudiment of a podobranchia in the eighth somite, but all the
other branchiae are represented. The podobranchiae of the following segments are very
small and are partially exposed, together with their reniform epipodites (fig. 34). In the
second larva the podobranchiae are covered by the carapace (fig. 41) and the branchial
formula is complete.

The gills are developed in the embryo as simple folds or pouches in the body wall,
(fig. 8, g. fil.) They belong to the trichobranchiate type, the respiratory surface being
gradually increased by growth of multiserial branchial filaments.

In the fourth larva the podobranchia carries four rows of filaments, and the
mastigobranchia, or epipodite proper, is a long, tapering, hairy plate.

The adult gill (pi. xxxvm), suggesting by its form a bottle brush, is a pyramidal tuft,
consisting of a central stem and numerous longitudinal rows of branchial filaments, which
enormously increase the area of the surface exposed to the water. The number of
rows of gill filaments gradually increases with the size of the animal and with its need
of a greater respiratory surface, until it reaches between 30 and 40 in an adult io}4
inches long, while the total number of filaments in such a gill is between 3,000 and
4,000. The filaments are “parted” into two groups by a median longitudinal furrow
and in the larger posterior section tend by transverse partings to separate into quad-
rangular masses. The filaments gradually lengthen in passing forward or backward on
either side of the “ part ” and terminate in several rows of short filaments next the efferent
division of the stem, opposite the body wall. Further, the filaments are so regularly
spaced that they come to assume an arrangement in circular rows from base to apex of
the branchia, corresponding to the circular efferent vessels (fig. 2, pi. xlvii c v) with
which they communicate.

NATURAL HISTORY OF AMERICAN LOBSTER.

247

THE BRANCHIAL CAVITY AND RESPIRATION.

The branchiae are lodged in a cavity of peculiar form upon either side of the body,
where they are securely protected by the broad sides of the curving carapace. The
gills (pi. xxxiv) arch upward in pyramidal form from the bases of the limbs and
the sides of the body to which they conform, those of successive somites being divided
by the gill separators or epipodites, which are hairy respiratory plates, springing from
the basal segments of the limbs. Currents of water set upward and forward from under
the free edges of the carapace, pass over the myriads of fine filamentous processes of
branchiae, and are led into a trough or groove at the forward end of this curved narrow
passageway on either side of the body. From this trough the water is fanned out by
the rythmic beating movements of the “bailer” or respiratory plate of the modified
second maxilla (see p. 228). The fan or respiratory paddle thus works with up-and-
down strokes in a narrow passageway,® which is horizontal in front, and behind curves
upward abruptly to the pyramidal apices of the gills. The lower bound of this passage
is formed mainly by the epipodite of the first pair of maxillipeds, which is folded over
so as to form a sort of trough in the part where the free inner division or epipodite of the
bailer plays (pi. xxxvi, fig. 3 fd.). This fold presses against the side of the carapace and
keeps water from entering the trough until it has passed over the lower half of the gills.
The outgoing stream is thus essentially limited to the forward upper part of the gill cavity.

By the alternate beating of the hinder (epipodite) and anterior (exopodite) divisions
of the bailer the water is driven forward and out of the cavity.

At the extreme hinder end of this chamber the carapace overlaps a small hairy leaf-
like plate belonging to the fourteenth somite and bearing a small oval lacuna in its
chitinous cuticle, just behind the pleurobranchia of this segment and above the hinge
joint of the limb. This corresponds to similar lacunae for the four pleurobranchiae in
front and without doubt represents the position of a former gill, every other vestige of
which has now disappeared.

As blood slowly passes through the 20 pairs of gills and their protective plates the
act of respiration is accomplished. Carbon dioxide diffuses from the blood through the
thin walls of the filament, and from the air dissolved in the sea water the oxygen supply
of the blood is renewed. The water in the respiratory chamber is kept stirred up by
the legs, to the bases of which 10 of the gills are attached, while the incessant
beating of the fan at the front end of the cavity (marked by the frothing which
commonly occurs when the animals are taken from the water) causes an active forward
flow through the chamber and over the gills as described above. If the motion of the
fan is stopped the animal soon becomes asphyxiated. The lobster will live for a long
time out of water, in some cases for upward of two weeks, provided the branchiae are
kept moist, and even in hot weather when the air is cooled by ice.

From the filaments the aerated blood is conducted down one of the efferent branchial
veins on the inner side of the stem in each gill, and thence through a distinct channel*
one of the branchio-cardiac veins, to the heart.

® The “ fan” has been noticed to beat at the rate of 95 to 178 strokes per minute in summer, in lobsters which had been
out of the water long enough to become quiet.

248

BULLETIN OE THE BUREAU OF FISHERIES.

COURSE OF THE BLOOD IN THE GILL.

The description of the course of blood through the gill given above usually
suffices for the text-books of zoology, but the physiologist wishes to know how the
blood circulates in the gill filaments, for if these were simple capillary tubes it would
tend to flow past rather than through them. The gill in reality is a complicated struc-
ture, and the actual course of the blood is not easy to follow.®

Each filament, like the stem of the branchia, is a double tube or vascular loop,
consisting of outer afferent and inner efferent divisions (fig. 2, pi. xlvii.) All the blood
must pass from the afferent branchial vein (af. v.) to the afferent divisions of the loops,
thence to the efferent divisions, and then to the main efferent of the stem (ef. v.). The
wall of the branchial afferent vein which carries unaerated blood to the filament sug-
gests a cylindrical sieve or grater, with fine holes arranged in regular transverse rows.
As the blood enters one of these holes it is conducted by a short passage to the afferent
division of the loop or filament, but, as Dahlgren and Kepner have shown, the course by
which the efferent half of the filament is reached is indirect. The venous blood in the
afferent section enters a plexus of fine channels or capillaries, by which it is conducted
around the filament and into the efferent loop. In the course of this passage the venous
blood is brought close to the cuticular surface, but never quite touches it, there being
always a cytoplasmic layer of the true epidermis of the filament, from which the cuticular
covering is supplied at each successive molt. Thus, in passing through the filament the
blood is kept in close relation to its surface, a condition which tends to promote the most
active exchange of gases essential to respiration. These capillaries do not, apparently,
have definite walls, but worm their way between or through the cells. The connective-
tissue cells of the central core of the filament are described by Dahlgren and Kepner
as being essentially peculiar and characteristic in possessing loosely branched proto-
plasmic processes. The efferent channel of each filament empties into a circular vessel
(fig. 1, pi. xlvii, c. v.) which runs around the main afferent of the stem, and thus
conveys the arterialized blood to the efferent vein (ef. v.).

The course of the blood through the gill is thus, in brief, as follows: Stem afferent
to filament afferent, through filament capillaries to filament efferent, to circular vessel in
wall of stem afferent , to stem efferent, to branchio-cardiac vein, to pericardium and heart.

This system of vessels is filled with blood, which, owing to the rhythmic contractions
of the heart and the dispositions of its valves, is kept moving in the same direction,
from heart to tissues, from tissues to gills, and from gills to heart again. The heart is
“arterial,” and the breathing organs of the crustacean are thus introduced into the
returning stream of venous blood, the converse of the conditions found in fishes, where
the heart is “venous” and the gills participate in the arterial system which leaves it.

o The account of the circulation of blood in the gill given in this section was written six years ago, when the drawings illus-
trating it were made. Certain details concerning the capillary plexus have been added since reading the work of Dahlgren and
Kepner, who, so far as we are aware, were the first to describe the histology of the filament and the course of the blood through it.

NATURAL HISTORY OF AMERICAN LOBSTER.

249

THE ALIMENTARY TRACT.

The alimentary tract (pi. xxxm) , extending from mouth to anus, consists of three parts,
which are quite distinct in origin, namely: (1) The foregut (stomodaeum of the embryo),
formed by a tubular invagination of ectodermic epithelium; this remains distinct until
late in embryonic life, and gives rise to the epithelial lining of the esophagus and grinding
stomach; (2) the midgut (mesenteron of the embryo), lined with endodermic epithe-
lium, and formed by the walling in of the great mass of the yolk by endodermic cells;
paired outgrowths or folds of the endodermic sac arise early in embryonic life and eventu-
ally form the liver of the adult; aside from the liver or gastric glands, the mesenteron
appears to take no part in the formation of the alimentary tract; (3) the hindgut
(proctodaeum of the embryo), formed by a solid ingrowth of ectodermic epithelium
which subsequently becomes hollowed out, its walls merging with those of the mesen-
teron; it gives rise to the lining of the intestine and caecum.

The foregut and hindgut, being infolded parts of the outer surface of the body, are
covered with a cuticle which is continuous with the chitinous exoskeleton, and is cast
off in the molt.

The grinding stomach.

The higher Crustacea are the only animals which grind the food after it reaches
the stomach as well as before it enters the mouth. Granivorous birds swallow their
food whole, and with the aid of gravel stones or other hard bodies pulverize it in a
muscular gizzard ; in a number of gasteropod mollusks analogous organs occur, but the
stomach mill of a decapod crustacean is a much more complicated machine.

When a bit of fish or clam is offered to a hungry lobster, it seizes the food with the
claws of the slender forward legs and passes it up to the mouth, where it is held by
the large maxillipeds. The cutting teeth and spines of the mouth parts, especially the
maxillae and mandibles, are successively brought to bear upon it, and chop it into
mince-meat, while it slowly enters the mouth in a stream of fine particles.

The stomach of the lobster is truly a complicated mechanism, and could not be
fully described without entering into great detail. In the brief account which follows
I shall rely mainly upon a study of this subject by Williams (279), which is by far the
best that has appeared.

The stomach sac (pi. xxxm and xxxiv) serves for storing, grinding, sorting, and
straining the food, as well as for delivering the finest particles in liquid streams along
definite channels to the intestine and to ducts of the liver; for, as Jordan has shown, the
huge gastric glands serve also for the direct digestion and absorption of food. Further,
the coarser particles of the food may be sent to mill time and again to be reground,
while the indigestible parts are regurgitated. Again, it should be added that newly
molted lobsters instinctively devour their own cast, and I have found soft lobsters
with their stomachs stuffed full of the shells of mollusks and other calcareous frag-
ments (see J49, p. 89), actions which point clearly to the need of the animals at such times
to obtain a supply of lime as quickly as possible.

250

bulletin of the bureau of fisheries.

The stomach is divided into a larger forward, or cardiac division, for storage chiefly,
and a smaller hinder, or pyloric section (pi. xxxm and xxxiv), mainly for sorting and
straining the food. Between the two lies the gastric mill, the grinding “stones ” of which
consist of a single dorsal median tooth and of two large lateral grinders. The wall of the
stomach is composed of two layers of connective tissue, in the inner and looser of which
are lodged the blood vessels and muscles, a gastric epithelium, and a chitinous lining.
The lining of the stomach is thickened in certain areas and hardened by deposits of lime,
to form the calcareous plates or ossicles which make up the framework of the gastric
mill; the largest and strongest ossicles culminate in the “millstones,’’ or teeth, just
mentioned. The lining of this organ is further thrown into various permanent folds,
pads, ridges, or bands, between which lie definite canals for the circulation of liquids
containing the comminuted food. Most of these parts are thickly studded with short
setae, which in general point toward the gastric mill, and serve to direct the food mechan-
ically into its proper channels, whether to or from the mill, whether into the pyloric
strainer or from this to the intestine and liver.

Aside from the grinding mechanism, the most essential parts of the stomach,
according to Williams, are the distributing and circulating canals (the upper and lower
cardiac and the lower pyloric canals) and the five food gates or valves, namely, the
cardio-pyloric valve between the two main divisions of the stomach and the four
pyloric valves which guard the passage of food to the intestine and the liver. There
is a small intestinal caecum, which extends forward over the dorsal wall of the stomach,
and the short duct of the liver or gastric gland opens into the intestine between the
ventral and lateral pyloric valves on either side. The conspicuous horn-shaped proc-
esses at the base of the pyloric sac and in front of the intestinal caecum are the lateral
pyloric pouches, where the finer particles of food are sifted out for delivery to the liver.
In addition to the canals mentioned there are also a pair which traverse the median
section of the pyloric sac. A small rudimentary tooth (infero-lateral tooth) is seen
projecting from between folds of the stomach wall immediately below the anterior end
of the lateral tooth, on either side (pi. xxxm).

Upon each side of the stomach sac, at its forward end, a large ovate plate (pi.
xxxm) is to be seen, called the gastrolithic plate (lying immediately above a small
gastrolithic bar). This plate is composed of a modified epithelium, which between the
molts secretes the rounded mass of snow-white prisms known as the stomach stones or
gastroliths. Williams has found that the gastroliths make their first appearance in the
fourth stage, when for the first time the skeleton abounds in lime.

Over thirty distinct plates, ossicles, and bars enter into the complex framework
of this organ, governed by some fourteen pairs of intrinsic and extrinsic muscles, some
of these serving to suspend the sac to the dorsal wall of the carapace (such as the
anterior, posterior, and lateral gastric muscles), for “turning the wheels” of the gastric
mill and feeding the “hopper,” as well as for dilating or constricting the cardiac and
pyloric chambers.

From the mouth the food passes into the short esophagus, through an esophageal
valve, and into the cardiac chamber of the stomach sac. Thence it is delivered through

NATURAL HISTORY OF AMERICAN LOBSTER.

251

the cardio-pyloric valve to the mill to be ground. The contraction of the anterior and
posterior gastric muscles reacts upon the articulated plates of the elastic frame in such
a way as to bring the lateral grinders together and to draw the median tooth forward
with great force. This upper middle tooth, or prepyloric ossicle, is shaped like a bird’s
beak and has brown indurated surfaces, while the lateral teeth, or surfaces of the zygo-
cardiac ossicles, the principal grinders, are divided by parallel transverse furrows into a
series of yellowish-brown hardened tubercles. According to Williams the forward and
downward movements of the median tooth tend to drive much of the food back into
the cardiac sac, so that it is reground again and again. Some of it, however, enters the
pyloric division of the stomach, and filters back and forth in its chambers and canals.
Here it is sorted and strained ; the finer parts, suspended in fluids, are delivered by the
canals to the intestine in four streams, while the coarser elements are swept up by
bristles of the cardio-pyloric valve and sent to mill again. Two streams from the
dorsal pyloric canal pass into the intestinal caecum; a stream from the middle pyloric
canal also delivers food to the intestine, while finally a current from the lower pyloric
canal conducts food particles to the lateral pouch, where a final sifting occurs, the
finest parts, suspended in fluids, entering the liver by the “bile ducts,” and the coarser
by way of the middle pyloric canal reaching the intestine.

When the muscles of the gastric mill relax, the elasticity of the framework is
sufficient to separate the parts. While it is not possible to see these movements in
the living animal, they can be roughly imitated by concerted pulls upon the anterior
and posterior gastric muscles. Undoubtedly the clashing movements of the teeth go
on for hours after a full meal until all of the food has been thoroughly stirred up,
brought to mill, ground, and reground. After the soft and semiliquid parts have been
filtered and delivered to the intestine and gastric glands, the indigestible residue is
regurgitated through the mouth, as is the habit with many birds.

The intestine is a delicate tube of small caliber, and since there are no coils it is
quite short. This suggests the need of a gastric mill, and the absorptive function of
the glands, for the area of the intestinal surface being limited, the digestive process
must be conducted as rapidly and efficiently as possible. As already seen, there is a
eaecal enlargement on the dorsal side of the pyloric sac of the stomach. The intestine
suddenly enlarges at the beginning of the sixth segment of the tail, where it gives off
from its dorsal side another slender blind pouch or caecum, which is apparently a rudi-
mentary structure. (PI. xxxiii.) From this point to the vent, which is closed by a
sphincter muscle, and from the mouth to the beginning of the intestine, the canal is
lined with cuticle which is continuous with that over the body and is accordingly
renewed at each molt. The embryology of the animal shows that the inner wall of the
intestine is primarily due to an ingrowth from the outside skin and in the early larvae
an intestinal cuticle can be detected, but if the latter is present in the adult it is
reduced to a layer of extreme thinness.

252

BULLETIN OF THE BUREAU OF FISHERIES.

THE LIVER.

The “liver” (pi. xxxm and xxxiv), called also the gastric glands, hepatopancreas,
and by the chefs “tomally,” is the largest single organ in the body. It is paired of a
green, bright yellow or yellowish green or yellowish brown color, and lies along the sides
and partly below the alimentary tract of which it is a part.

The liver is a soft, lobulated mass, divisible on either side into three parts — a thick
anterior lobe, a long posterior lobe, and a less clearly marked dorsal or lateral lobe.
Each lobe is composed of many lobules, and each lobule of a multitude of short aggre-
gated tubes called the caeca. The lobules are covered by a delicate transparent mem-
brane, and when this is broken can be shaken out in water like tassels.

A part of the secretions of the cseca is gathered by a system of converging tubes and
is finally admitted to the pyloric division of the grinding stomach, near the junction of
the latter with the intestine. These ducts also serve to admit streams of food particles
(see p. 249) to the glands themselves, where they are acted on by ferments and are directly
absorbed.

THE KIDNEYS OR GREEN GLANDS.

The direct excretion of nitrogenous waste products is effected by a pair of glands
which open at either side by a prominent papilla on the lower side of the basal segment
of the first pair of antennae. (PI. xxxm and fig. 6, pi. xxxv, g. gl.) In their funda-
mental relations these organs agree with the segmental nephridia of worms and
vertebrates.

When unraveled, the entire organ has been found to consist of the following parts:
A large, thin-walled peripheral vesicle or bladder, and closely applied to this, in front
or below, the proper excretory organ or gland. Together these parts form a rounded or
flattened body of a light green color, closely fitting in the convex depression over the
articulation of the antenna on either hand and just in front of the stomach sac.

The bladder empties to the outside by a short duct, the opening of which on the
papilla is guarded by a valve. The kidney proper is composed of a central saccule or
end sac, and of a convoluted tubule, both of which are glandular. According to Dahlgren
and Kepner (67) the tubule is lined throughout with nonciliated epithelial cells, and
is covered by a tunic of connective tissue, it being in this section only that a cuticle
is secreted. Upon taking a lobster in hand a fine jet of liquid is sometimes thrown from
the papilla to a height of an inch or more. Inasmuch as water does not apparently have
access to the bladder, the walls of which are contractile, the liquid is probably a true
secretion. This fountain display of the green glands has been noticed but two or three
times.

Chapter VII.— THE GREAT FORCEPS OR BIG CLAWS.

THE CRUSTACEAN CLAW.

The last ten thoracic legs of higher Crustacea all end in hard-pointed segments
technically known as dactyls. In the account which follows, when not thus desig-
nated, they will be called “single claws,” “nails,” or “digits,” the original meaning of
the word. In Palinurus , the spiny lobster, all of the thoracic legs end in talon-like
claws of this simple type; but in the true lobsters, crayfishes, crabs, and many other
decapods a unique organ is developed in certain of the forward legs by the extension of
an opposable finger-like process of the subterminal segment, the propodus, which is
often large and powerful. In the great cheliped of the lobster (pi. xxxm and xxxvii)
this division is also called “the hand” and the terminal part of it the “index,” as dis-
tinguished from the opposed “thumb” or dactyl. Thus is formed the admirable
forceps, commonly known as the “claw” or chela.®

Those legs ending in forceps are described as chelate and the others as nonchelate,
and the technical use of these terms is unobjectional. This, however, need not lead to
the ambiguity of saying that the last two pairs of legs in a lobster or crayfish have no
“claws.” To avoid this absurdity, we may adopt Huxley’s terms, “ double claws ” and
“single claws” for the forceps of the first three and the nails of the last two pairs of
legs, respectively, since they describe the conditions met with in both lobsters and cray-
fish exactly. The chelate legs all pass through the simple claw stage in either the egg or
early larval state.

The big claws of the lobster are remarkable organs whether considered in the light
of their structure, their development, or the process of their renewal, and the more we
study them the more remarkable they appear.

In most of the higher Crustacea the great claws are the chief weapons for both
attack and defense and very efficient means for seizing and rending the prey, as well
as for grasping and holding the female in the act of pairing, when the spermatophores
are transferred to her seminal receptacle or to some other part of her body.

While three pairs of pereiopods in this animal bear double claws or forceps, in the
first pair alone are they entitled to be called “great.” In many crabs, as well as in
the lobsters and crayfish, the great claws are weapons whose grip is not to be despised.

In some of the crayfishes the great chelipeds are equal to about one-quarter of the
weight of the entire animal, while in lobsters above medium size their proportionate
weight sometimes reaches one-half, and tends to increase with age. Moreover, the
disproportion between the big claws of either side, which are normally asymmetrical,

a Latinized from the Greek word for any armed appendage; in plural form chelae, corrupted from chele.

2 53

254

BULLETIN OF THE BUREAU OF FISHERIES.

tends also to increase with age and in favor of the “crusher,” which in old males reaches
an extraordinary size (fig. i). Many crayfish when incautiously handled readily draw
blood, and there can be little doubt that a lobster weighing upward of 30 pounds could
easily crush a man’s arm at the wrist.

The differentiation of the large claws is often very marked in crabs, and all degrees
are represented. The character of the adaptation is equally varied, as may be seen in
the common green crab ( Carcinus mcenas ), the fiddler ( Gelasimus pugilator), and in the
“king crab” of the West Indies ( Caleppa marmorata). In Carcinus the slightly larger
claw is of the “knobbed” or crushing type. A singular differentiation has apparently
been started in the same direction in the more remarkable Caleppa, where the great
chelipeds have been modified in a different manner for the protection of the animal. The
great trihedral claws of this singular species swing in and out in front of the head like
double doors, and when these are closed or folded in, the crab is as secure as the tortoise
in its shell.

In many of the small shrimps belonging to the Alpheus family, the huge “hammer”
claw, which is usually largest in the males, is most interesting, whether considered
as a “snapper” or popgun, as a saber for delivering a slashing blow, or as a means of
controlling the development of its fellow in regeneration (see p. 277).

But of all the crustaceans known to me the shrimp-like Jousseaumea which I found
at Nassau, Bahama Islands, in 1887, but did not describe, presents the most singular
differentiation of the claws. When viewed from above this animal presents a very
deceitful appearance, no formidable weapons of any kind being visible. In reality, it pos-
sesses a huge and ugly looking claw, which in rest is completely concealed, being nicely
folded like a pocket rule and tucked under the grooved cephalothorax, ready at any
moment to be shot out and to strike an unsuspecting victim. The fellow to this
“pocket” weapon is very diminutive. Were this little shrimp as large as the common
lobster it would be justly regarded as one of the most remarkable animals in the sea.

While in Cambarus and in crayfishes generally right and left claws may be more
or less unequal in size, they are often very similar in structure and function, suggesting
the primitive toothed type seen in the lobster, but not approaching it with any degree
of detail. There is no lock spine in Cambarus, but the hooked tips cross, the dactyl
underlapping the propodus. The armature consists of small rounded tubercules, set
like a row of corn on a cob. When this claw is closed a large gap is left at the proximal
end where the teeth are most numerous, and the fingers touch only at their tips.

the; great chelipeds.

The legs which carry the big claws consist of the 7 typical segments already enu-
merated (pi. xxxvn), united to the body and to each other by articular membranes,
and moving in the way described on double hinges of variable form, excepting only
the basis and ischium, or second and third segments, which after the fourth or fifth
stage fuse into a single piece. This limb in the adult state therefore possesses 6 free
podomeres and 6 free joints. The suture of the stiff joint (x in all figures) marks the
“breaking plane,” since whenever the lobster “shoots a claw,” the limb always breaks
at the suture of this joint.

NATURAL HISTORY OF AMERICAN LOBSTER.

255

The musculature of the great chelipeds is essentially normal and like that of the
slender legs, with the exception of the basis or second segment, which has no muscles
in the adult state, a condition to be considered in relation to autotomy and the breaking
joint; as in the smaller pereiopods the ischium carries two posterior extensors only.

The hinges of this limb are quite peculiar, and suggest possible adaptations to the
“breaking joint,” and “interlock,” considered in a later section. In place of anterior
balls working in posterior sockets, as in the tail, we have proximal balls moving in
distal cups,® with the exception of the first, fifth, and sixth podomeres, for the hinges
between the carpus and big claw are so peculiar that they merit special attention. As
we have seen, the order in the hinges of the basal joints of all the thoracic appendages is
socket and ball of limb, united to ball and socket of the body.

LOCK HINGES OP BIG CLAWS.

By far the most peculiar joint and one of the most unique mechanical devices in the
lobster’s skeleton are the concealed, sliding hinges, by means of which the great forceps
are securely locked and articulated to
the rest of the limb. By referring to
plate (xxxvii and text fig. 4) it will be
seen that the great claw swings between
flattened processes of the carpus, which
embrace the upper and lower sides of
its proximal end near the joint. These
two processes (u and / h p) conceal
the joint in question, and lock the claw
firmly to the carpus, upon which it is
free to move in the horizontal plane
through an arc of about 1350, but
from which it can not be removed
without breaking either segment.

When the hard shell is broken at
this joint the upper hinge on the claw
side is seen to consist of a prominent semicircular ridge, which fits into a corresponding
carpal groove, but of greater length. Further, on the inner or proximal side of this groove
rises a ridge of lesser arc, which runs in a corresponding groove under the curved ridge
of the claw; in brief, circular ridge and groove of claw work on corresponding groove
and ridge of fifth segment. To complete this adjustment there is an outgrowth from the
hinge process of the carpus, which is outwardly curved, and runs in a corresponding
groove distal to the articular ridge on the claw; this serves as an additional lock to the
joint, but the proper articular surfaces are those described above. Turning now to the
lower or originally anterior side of the claw, we find the conditions completely reversed,
and instead of ridge groove we have groove ridge, with corresponding ridge groove on

a These terms are used for the successive segments of the limbs in reference to the median plane of the body. The dacty
possesses proximal balls only.

Fig. 4. — Locked sliding joint of big claw of lobster. Sectional view
of left chela seen from side towards median plane of body, show-
ing reversed grooves and ridges of upper and lower hinges. This
locked joint is strengthened by the overgrowth of upper and lower
hinge processes (u h p and l h p), which arise from the carpus.

256

BULLETIN OF THE BUREAU OF FISHERIES.

the lower hinge process of the carpus. It follows from these relations that the articular
surfaces of the carpus face, while those of the claw look in opposite directions.

This remarkable joint suggests the hinge of an ordinary folding pocket rule, but with
a different locking device. It is neither a true pivot, tenon-and-groove, or ball-and-
socket joint, and so far as I am aware its principle is not found embodied in any of
the common mechanical devices. We find it well developed at the fourth stage, with
little later change except in the further overgrowth of the hinge processes. (Fig. 9.)
Such a joint works with great precision in its prescribed plane, with little or no appreci-
able lost motion, and would seem to be an adjustment by means of which the big claw
is firmly secured to the supporting carpus, and the voluminous flexors of this segment
can react upon the great weight of the claw to the best advantage.

In the crayfish ( Cambarus ) the big claw is not locked to the carpus, but moves loosely
on double hinges of the typical ball-and-socket order, each hinge consisting of carpal

ball, and propodal socket mounted
on a round tubercle. In Callinectes
and certain other Brachyura exam-
ined (text fig. 5) the great cheliped
has suffered little or no torsion,
and the dactyls open upward as
in the larval lobster. The claws
move on modified ball-and-socket
hinges, which are firmly locked to
the claw but in quite a different
manner from that of the lobster.
The propodus in this case bears
cups [l h (socket) fig. 5) on both
upper and lower sides, which are
locked over the balls by processes
(u and l h p) growing out from this
segment and not from the carpus.
The crab’s claw thus swings vertically in and out through an angle of upwards of 90°.

While the locked, sliding joint of the lobster, particularly in the reversal of its
hinges, suggests the ordinary ball-and-socket device of the other limb segments, and
even more that of the crab’s chela, it would be difficult to decide whether one was
better from a mechanical standpoint than the other, or to imagine how either could
have arisen from the simpler type upon any principle of selection.

ASYMMETRY IN THE BIG CLAWS OF THE LOBSTER.

The marked dissimilarity of the big claws (pi. xxxvii) in regard to both their
structure and chief functions in all lobsters above an inch or an inch and one-half long,
has led to various distinctive names on both sides of the Atlantic. Fishermen often
speak of the “knobbed” and “quick” claws. The larger is adapted for crushing the

Fig. 5. — Locked sliding joint of big claw of crab ( Callinectes hastatus );
in same plane as represented in figure 3, showing modified balls and
sockets, but with no reversal on upper and lower sides; hinge processes
(w and l k p) here arise from the propodus of claw.

NATURAL HISTORY OF AMERICAN LOBSTER.

257

food, and to emphasize the function, we shall call it the cracker, crusher, or crushing
claw; the smaller and slenderer, which suggests a patent lock forceps with serrated jaws,
is used for seizing, holding, piercing, tearing, and slashing the prey. We shall call it
the lock forceps or toothed claw, in preference to the phrase “cutting claw” formerly
used. In young animals from 2 to 5 inches long the teeth of this weapon are completely
concealed by dense clusters of sensory hairs, which though seldom absent become less
conspicuous with advancing age. It is therefore evident that the toothed claw is highly
sensitive and “feels” the blows it gives as well as those it takes.

Przibram (223), who classifies the higher Crustacea according to the similarity or
differentiation of the big claws into the “ Homoiochelie,” and the “ Heterochelie,” calls
the larger claw the “Knoten” or “ Knackschere,” and the smaller the “Zahnchen” or
“ Zwickschere,” in view of their form and function respectively. Stahr (257), who uses
the terms “ Zahnchenschere ” (toothed claw), and “ Knotenschere” (knobbed claw), as
descriptive of their structure, after a discussion of their probable functions, says that he
is justified in designating the claws of Homarus gammarus as follows, “the beautiful,
regular, elegantly formed, thin-walled forceps, provided with periodic teeth and sensory
hairs as the ornamental (“Schmuck-”) and sensory claw (“Spiirschere ”), and the other,
plump, oval, thick-walled form, provided with tubercles, as the crushing (“ Knack-”) and
grasping claw (“Greifschere”). As will later appear, the development of these organs
affords no warrant for regarding the toothed claw as an ornament, not to speak of the
psychological difficulties involved.

TORSION OF THE LIMB.

Of greater interest than the difference in size and structure of the big claws is the
complete change in their position on either side which takes place after birth, due to a
twisting of the limb and mainly of the fifth joint or carpus or the third podomere reck-
oned from the distal end.

This curious torsion of the crustacean leg is of very ancient origin, dating from as
early as the Cretaceous period, and is shared by many of the higher Crustacea decapods
(for first account of torsion and fuller discussion see 153). It further affords a good
illustration of how a very obvious fact may long escape the notice of naturalists, my
own attention not having called to it until 1905, although drawings of the larval and
adult stages had been repeatedly made.

In the adult lobster or crayfish the free dactyls of the smaller chelate legs all open
upward and outward in a plane which is nearly vertical, while in the big claws the
dactyls of opposite sides face and open inward or in a nearly horizontal plane. In the
lobster at birth, on the other hand, and up to the fourth stage, all the chelae have the
same relative positions; all open vertically upward with an outward inclination. (Com-
pare fig. 1, 6, and 7 with pi. xxvur.)

It is thus evident that the position of the great forceps in an adult animal has been
reversed through a rotation of either claw through an angle of 90°, toward the median
plane of the body, in consequence of which their inner or anterior faces have become
48299° — Bull. 29 — 11 17

258 BULLETIN OF THE BUREAU OF FISHERIES.

their under sides. This rotation is completely effected at the fourth stage (pi. xxxi)
and with the molt which registers so many other marked changes in the structure and
habits of this animal. It is responsible for the torsion or twist to be clearly seen in the
carpus of the limb. In conformity with this change in position, the claw has undergone
a change in coloring, for the deep green chromogen pigments which cover the present
upper surfaces are completely lacking from their pale red under sides.

It would appear in the highest degree improbable that this condition in the big claws

could have been produced through the in-
heritance of slight variations leading to a
greater and greater degree of torsion, and
finally extending through so great an arc,
although it is conceivable that such a
variation may have been correlated with
others which were of so favorable a char-
acter as to be of selective value and to
have been “dragged” along with them.

Again, it is even more difficult to re-
gard this torsion of the crustacean limb as
the resultant effect of use through inher-
itance. The carpal podomere has but
one flexor and one extensor muscle, both
of which react on the claw at points out-
side of the joint itself; at the same time
the muscles, of course, pull on the shell
of this part at their points of origin, but
no conceivable position or strain of these
fibers can convert the pull into a twist.
If the increasing weight of the claws in
the growing animal had any effect upon
their ultimate position it should tend to
turn them outward. In other words, their
modification is just the reverse of what
we should expect were the effects of
strain or use inherited.

If we examine other crustaceans we
find that the big claws open inward, up-
ward, or outward, irrespective of their
relative size or weight. In the Alphei, which usually have one claw of enormous size
and of peculiar structure, the dactyls open outward, while in the fiddler crabs ( Gclasimus
pugnax ) they incline inward, as in the lobster. This is true not only of the single huge
claw of the male fiddler but of its diminutive fellow and of the small, almost rudi-
mentary chela of the female. In the common crabs ( Carcinus , Callinectes) the claws
open obliquely outward. It therefore appears that in the rotation of the crustacean

Fig. 6 and 7. — Great first and small left third claw feet of adult
lobster with pins (mo. 2-7) inserted in the axes of articulation
of successive podomeres, to indicate normal torsion in the great
cheliped. Position of the big claw up to the fourth stage is iden-
tical with that of the little claw of the slender leg. Compare
plates xx vm and xxxi, with figure 14 of text. Cp carpus; D,
dactyl, and X, breaking joint. Podomeres or segments oi per-
manent limb numbered, as in all succeeding figures, in Arabic
numerals, from base to apex.

NATURAL HISTORY OF AMERICAN LOBSTER.

259

limb we have an illustration of an adaptive variation, which in origin and the extent
to which the process may be carried is independent of use and the mechanical strains to
which the organ may be subjected.

Apart from their crushing or piercing teeth and sharp indurated tips, the large claws
are armed along their facing edges by stout tooth-like spines, while the exposed sur-
faces and angles of the lower segments of the limb are similarly protected. These spines
are generally directed forward and mostly upward and tend to guard the space about
the head which the outstretched claws inclose (see, p. 273).

The terminal segments of the last pair of slender legs have undergone torsion but of
a different character, as described in chapter ix, page 304.

BREAKING PLANE AND INTERLOCK.

We have seen that both of the large chelipeds have a stiff or breaking joint in the
compound segment at their base, as well as peculiar hinges, which are not only adapted
to the ordinary uses of such limbs, but possibly to the resources of the animal in sacrific-
ing them for its own preservation. There has also been developed in relation to the
breaking plane an interesting interlocking mechanism, which seems to have escaped
notice up to the present, although its importance in the life of this animal would appear
to be great.

This interlock (fig. 1,3, and 4, pi. xxxvii) is a simple but effective adjustment by
means of which it is impossible for an enemy to pull out or twist off one of the chelipeds,
as may be done in a cooked lobster, without bringing autotomy into play, to which
process it seems to form a sort of emergency “brake.”

Turning the body of the lobster over and working the chelipeds by hand, we per-
ceive that they move freely forward and backward, the striking or thrust movement,
at the junction of coxa with basis. In such movements the lobster’s most powerful
blows are dealt, whether in attack or defense. We observe further that any lateral
movement of this joint would be serious, and that is guarded against by huge inter-
locking spurs (s1, s3) on the first and third podomeres respectively. This condition
seems to be related to the fact that the breaking joint (x) lies between these points,
or peripheral to a free joint, so that when the strain upon this articulation and the inter-
locking spurs is too great or, in other words, sufficient, the limb is reflexly cast off in the
breaking plane.

This mechanism, moreover, together with the complete fusion of the joint, is not
developed until after the fourth stage, when there is probably less need of strengthen-
ing the hinges between these particular segments. Yet autotomy occurs at this stage,
and we find the hinges strengthened in a degree by the interlock of distinct but different
spines (fig. 8-10, r4, and r2), although this early adjustment is not quite so marked
as in the adult animal. At all events in the lobsterling there is an interlock between
the second and third podomeres, which evidently increases the resistance of the limb
at its base during this period. These spurs of the fourth stage lobster become later
reduced to rudiments, and new interlocking processes are developed in the adult animal

26o

bulletin of the bureau oe fisheries.

between the first and third segments. The principal spur at the fourth stage (fig. 8, s2)
is still to be seen in its rudimentary state in the adult lobster immediately in front
of the large functional spurs already described. (PI. xxxvn, fig. i, nid.)

THE TOOTHED CLAW OR LOCK FORCEPS AND ITS PERIODIC TEETH.

— i

If the armature of the smaller claw is closely examined, the teeth or spines are
seen to be arranged in periodic sequence, a fact first noticed by the German naturalist,

Stahr (257). Stahr’s description is correct,
so far as it goes, but we can not adopt his
remarkable conclusions that this should be
called the “ornamental” or “beauty claw,”
and that the aesthetic sense of this self-
admiring crustacean is aroused as its eye
wanders over the dentate margin of its
“hand.” We should fail, however, to do
justice to the imagination of this writer
without quoting directly from his work, in
which he concludes “That it is not a far-
fetched idea to recognize in the periodic
teeth or rows of points of the ornamental
and sensory forceps an embellishment — an
architectural and artistic ornament. We
may mention their close relation to music,
poetry, and dancing, where we have to
do with rhythm, time, measure, composi-
tion, everywhere with periodic sequences.
* * * Thus it is only natural to sup-
pose that the beauty sense of a crustacean
would receive an agreeable impression as
its eye wanders over the periodic points of
its claw.” a

We have worked out the history of de-
velopment of both types of claw, in the light
of which their peculiar structure becomes
more intelligible. The arrangement of the
teeth or spines on the smaller claw may be
expressed by a diagram (fig. 11), in which
they appear as a linear series, made up
typically of periods of eight. In respect to size and age, or order of development,
the eight teeth of each period are symmetrically distributed and fall into four orders
or series, of which the first and second contain one each, the third two, and the
fourth four. On this basis the formula for each perfect period or sequence would

Fig. 8. — Base of right great cheliped of fourth stage lobster from
below, showing future breaking joint free at surface, before
complete fusion has occurred, a temporary interlock at this
stage by spurs {s2 and ri) of the second and third podo-
meres, as well as rudiments of the spurs (^3 and ri) of the
first and third segments, which form the permanent interlock
of the adult limb. Compare with figure 13. Swimming
branch or exopodite {Ex) functional up to this stage is re-
duced to a rudiment. Gill filaments ( g.fil ) are developed as
secondary outgrowths of the primary filament, which is a
fold of the body wall.

a All quotations from foreign languages in this work are freely rendered into English.

NATURAL HISTORY OF AMERICAN LOBSTER.

26l

be: 1 +1 +2+4=8, or, designating each spine by its serial number as in table 6,
1 :4 :3 14 :2 14 13 :4=8.

About midway on the dentate margin of the “hand” (fig. 12 and 13) or propodus
one finds a stout spur which I shall call the “lock spine” (L in all the figures). As
we shall see, it is really a displaced spine of the first order. It fits into a shallow groove
of the dactyl, which is often slight or
wanting, and forms the lock of the claw.

Upon closing, the dactyl falls on this
spur, and, its teeth sliding under those
of the opposed jaw, it is firmly locked
in this position, so that no lateral mo-
tion is possible. (Fig. 1, pi. xxxvi.)

To complete this adjustment, the tips
of the forceps are bent like the man-
dibles of a crossbill, the dactyl under-
lapping. The spines of the propodus
are bent upward, those of the dactyl
downward so that in the claws of some
individuals they make an angle of 45 0
withthe lock spine, which isnearly ver-
tical. Moreover, the spines are aligned
very accurately, and in a peculiar man-
ner. The spines of the “upper jaw”
or propodus are all tangent to a line
traversing its lower border, while those
of the dactyl or underlapping jaw meet
a line drawn along its upper margin.

This reversal of the alignment it will
be observed makes it possible com-
pletely to close and at the same time to
lock fast the jaws of an instrument
having this structure. It follows that
the teeth do not interlock but overlap
(fig. 12 and 29).

The tendency of the spines to in-
crease in geometrical ratio is often
present and if effective would in the
next progression give a period of 16
spines. Under these conditions the periods are generally incomplete, seldom yielding
over 13 spines.

The formula given above seldom holds good for more than two or three periods,
and in many claws no period is quite perfect. At both proximal and distal ends of the
series the periods become irregular and the identity of the spines is lost. Some means

Figs. 9 and 10. — Right great cheliped of fourth stage lobster, from
above, showing upper hinge process (u h p) of carpus, and disar-
ticulated ischium with interlocking process (s'1), and future inter-
locking spur (s3), which is rudimentary. Compare text figure 8,
and plate xxxiv, figures 1,3, and 4.

262

BULLETIN OF THE BUREAU OF FISHERIES.

of identifying the principal periods, however, is necessary, if we are to follow the course
of development and the changes which attend the molt. Fortunately two guideposts
are always present at either end of the series, the lock spine (fig. 12 L) and a distal
spur or tubercle on the lower side of the propodus near its tip ( Sp .) For convenience
of description we assume, then, that the first period lies proximal to the spur, and that
the “lock” spine is the primary member of a hypothetical fifth period. Between these
boundaries lie three, four, or exceptionally five, periods, of which the fourth is rarely
perfect. This leaves three or at most four periods (numbered in all the figures i-iv)
for special consideration.

Counting the tip of the claw as a primary spine (though it really is not, since it
develops as a seta), we should have from five to seven periods between it and the lock

Is* stage
2d stage

3^ Stage

4fr'stage

A A

A A ,

1 2

A A ▲ A

1 2

1 3 2 3

13 2 3

1 4 3 4 2 4 3 4 1 4 3 4 2 4 3 4

Period J. Period H.

Fig. ii. — Diagram to show the serial arrangement of the spines in the toothed forceps of the lobster in periods of 8, and
the development of these spines by interpolation from the first to the fourth stages. Arabic numerals indicate orders
of teeth (here reading from left to right).

spine. Proximal to the lock spine, the linear series is completed by from three to five
primary teeth, with small secondary spines among them, which like similar spines else-
where are a fluctuating quantity. Consequently in the propodus there are from 8 to
12 primary spines which represent periods, of which never more than 3 or 4 are com-
plete, or in eights. (Compare fig. 29.)

In order to set these relations in clearer light as well as to illustrate individual
variation I append a table of formulae for the teeth in the large segment of the toothed
claw of 10 lobsters taken at random (table 6), and of the teeth before and after the
molt in the claw of an adolescent (no. na, 11 b, stages vn and viii) and an adult animal
(no. 12 a and 12b).

NATURAL, HISTORY OF AMERICAN LOBSTER.

263

Table 6. — Sequence oe Spines in Periods I-IV of Toothed Claws of Adult, and in Periods
I— 1 1 1 of Molting Adult and Adolescent Lobsters.

No.

Period I.

•

Period II

5 4

5 3

5 4

5 3

5 4

1 5

5 4

3 5

2 a

1 5

5 4

1 5

no ( VII :

ii b (viii)

12a

1 5

12 b

1 5

No.

Period III.

Period IV.

Summation of
periods.

2 a

i 5

5 3
3

4 5
4

5 4 5

2 5
2

3 5 4 5

3 4

16+16+16+16= 64
8+8+8+8=32

10+10+8+3=31

1 5

3 4

9+11+9+8=37

1 5

10+12+10+2=34

1 5

3 4

9+9+9+8=35

1 5

3 5 4

9+9+10+10=38

3 4

8+11 + 8+7=34

6+7+7+8=28

1 6 5

4 5

3 4

7+8+10+10=35

5+9+7+2=23

9 + 6+6+3=24

11 a (vii)

1 5

8+H+8

1 16 (vni)

165

8+10+n

I2d

8 + 10+6

12b

9+12+8

It will be observed that four periods usually occur between the spur and lock
spines; that in ten individuals only seven regular 8-tooth sequences occur; in one there
are two, and in four cases none. The disturbances arise from the interpolation of
exceedingly small spines, or the tendency to advance to the next progression, which if
complete would give 16 spines to the period. The largest number of spines to the
single period given in the table is 12, but I have seen a case in which the third period
contained 15 spines.

A fairly regular claw of large size is represented in profile and horizontal projection
in figures 12 and 13, the formula of which for the four principal periods is 31 (table 6,
no. 1), only one of the sequences being in eights, and the spines of the entire armature
totaling 48.

The serration of the dactyl of the toothed claw is more regular than that of the
propodus and similar except for the disturbance introduced by the “lock spine” of the
latter. Three or four 8-tooth periods usually occur and the sequences are often perfect.

264

bulletin 0E the bureau of fisheries.

The toothed claw, as already remarked, is richly supplied with tufts of sensory hairs
above and below the line of teeth and also along the margin of the claw near its tip.
These are specially abundant on the underside, and with them the animal is constantly
feeling the bottom when it assumes the common alert attitude with the tips of the claws
bent down. These tactile setse are arranged in bundles of 200 to 300 or more short, stiff

bristles which, like little scrub-
bing brushes, project from de-
pressions in the shell. The
floor of each depression is a
sieve plate, the perforations of
which correspond to the num-
ber of setse as well as to the
number of nerve fibers supply-
ing the bundle. In the adoles-
cent stage, when the lobster has
attained a length of 3 or 4
inches, the setse of the lock forceps become large matted tufts which sometimes com-
pletely conceal the teeth. (Compare fig. 15 and 16).

THE CRACKER OR CRUSHING CLAW.

In place of tooth-like spines the great crushing claw presents a number of rounded
tubercles, both large and small, single or double, and arranged in a characteristic manner
(fig. 2 and 3, pi. xliii). These crushing tubercles are very dense, and in old hard-shell

Fig. 13. — Large segment of right toothed claw from above, to show the periodic teeth; compare
projection in figure 12; u h ( ridge ), upper ridge of sliding lock joint.

lobsters the pigment and enamel is completely worn away from long and rough usage.
The tips overlap slightly, but the dactyl is curved, and not straight as in the toothed
claw, consequently when closed there is often a wide gap between the jaws, the tubercles
touching at but one or two points only. (Fig. 2, pi. xxxvn.)

The crushing claw, as shown in the drawing (pi. xl), has a far more powerful muscu-
lature than its fellow, and is accordingly richer in its supply of blood vessels and nerves.
Two tendons (fig. 2, pi. xli) spring from opposite sides of the proximal end of the free

V A

S’

Fig. 12. — Projection of serial teeth in segment of big claw of large adult lobster
represented in figure 13, showing alignment to lower or ventral ( v ), originally the
anterior, side, the position of the tip, spur (Sp), and the large displaced lock
spine (L), the two last serving as guide posts for identification of the periods
i-iv. In this and following figures the periods are enumerated from the distal
to the proximal end of the claw.

NATURAL HISTORY OF AMERICAN LOBSTER.

265

dactvl and afford a surface for the attachment of the huge flexor and smaller extensor
muscles. Each tendon is a keeled plate which is developed in a flattened pocket of the
skin, but the closing muscle of the great claw being the largest and the strongest in the
body requires the largest tendons. The tendon of the flexor (t. fl.e) is a broad leaf-
shaped plate, keeled above and below, while that of the weaker opening muscle is narrow
and strap-shaped.

At the time of molt these huge tendons, like all others in the body, are drawn out,
attached to the cast-off shell, and leave deep open pockets into which in a large animal
the little finger can be easily inserted. As soon, however, as the soft claw becomes
tense with blood, the water is driven out and, the opposed surfaces of the pocket uniting,
a new tendon is gradually formed. (Compare fig. 1 , t p, pi. xliii.)

The coarser flesh of the claws represents, as we have indicated, the characteristic
flexor and extensor muscles, while the “ fine meat ” of the dactyl (fig. 3, pi. xlvi) and distal
half of the propodus is composed of a sponge work of involuntary muscle fibers in addition
to fine-blood vessels of the arterial system, nerves, glands, and connective tissue, the
whole being enveloped by the soft pigmented skin (pi. xl). No special sense organs,
aside from the setae, have been detected in it. The meshes of the sponge work form
a system of communicating sinuses into which the arteries appear to open through very
small branches or capillaries.

During the molting process, when the fleshy mass of the claw is drawn through a
series of narrow rings as if it were a piece of candy, the blood is of necessity withdrawn
from these parts. The sponge work is an adjustment which meets this prime need of the
molting period. At the time of molt the muscles are extremely tense and the flesh hard,
and the contraction of the fibrous sponge work apparently keeps back the flow of blood
until the animal escapes from its old shell, when it again becomes completely relaxed
(see p«2o6).

The abundant blood always found in the large claws, except when molting, is supplied
by a large artery, which at the point of entry from the fifth segment divides into an inner
and a smaller outer branch. The inner division passes between the two muscles, and
gives off small twigs in its course; then as it curves outward over the distal end of the
flexor muscle, it sends off somewhat irregularly a branch to the upper and lower division
of each muscle, and to upper and lower parts of dactyl and propodus.

The nerves of the great cheliped (pi. xl) consist of two main bundles (n1 and n2),
made up of a number of closely related strands. In the basal segments of the limb the
larger and more complex bundle (■ n 2) is anterior while the smaller bundle ( n 1), which is
double, follows it closely on its posterior or outer side.

The nerves usually enter the claw in three closely related strands, one of which, sup-
plies chiefly the extensor, one the dactyl and flexor, while the outermost branch is dis-
tributed to the flexor and large “finger” of the claw. Both arteries and nerves regularly
divide and subdivide in the terminal parts of the claw to form a very complicated
system.

266

bulletin of the bureau of fisheries.

DEVELOPMENT OF THE GREAT FORCEPS.

How has the differentiation of the great claws been brought about? It is easy to
follow the history of their development molt by molt from the first larval stage onward.
This history clearly shows that the toothed claw represents an original or an older
type, and that the crusher claw was later developed by a modification of this primitive
pattern.

In the first larval stage of the lobster the future big claw (fig. 14) is distinctly of the
embryonic type, relatively short and thick, and armed with few tactile bristles, its tips

being drawn out, as it were, into
long sharp-pointed spines. The
dactyl, which bears the longer
and straighterspine, is larger than
the undeveloped index. This in-
equality is much more marked in
the smaller chelipeds, where the
index appears as a bud-like out-
growth, setate and bearing one or
more stiff, barbed, or serrated
bristles (fig. 2).

In the second and third larvae
(fig. 41 and 42) the claws become
broader and more voluminous,
while their spinous tips are re-
duced and both index and dactyl
are curved.

In the fourth stage (fig. 9 and
pi. xxxi) the great chelipeds sud-
denly become very conspicuous,
bearing long slender forceps which
now for the first time serve as
show- organs of prehension with marked
ui-red, success. The jaws of the forceps

>, and

are slender, dentate, and tufted
with tactile hairs. The condition
of symmetry, with this general structure, on right and left sides, continues through the
fifth and in some cases up to the seventh or eighth stage, when the first traces of asym-
metry begin to appear, though not necessarily apparent to the naked eye. (Fig. 15 and
16.) By the ninth stage, when a total length of about one and one-quarter inches has
been reached, the differentiation of the crusher claw is easily recognizable, but the
changes registered at each molt are slight. In the account which follows we shall con-
sider in more detail the beginnings of asymmetry and the development of the teeth
and tubercles which characterize the two types of big claw in the adult animal.

the short ischium (3), with free joint at future breaking plane (*
base of swimming branch (Ex). Compare with text figures 6 and 9.

NATURAL HISTORY OF AMERICAN LOBSTER.

267

In the fourth stage the great claws are not only symmetrical, but of the toothed
type. According to Emmel (96) the transition to the asymmetrical condition begins
in the sixth stage, but in the material studied as a basis for this account it was impossible
to detect any morphological differences until the seventh or succeeding stage. There is
doubtless some variation in this respect. It is true that at preceding periods the big
claws may differ in size or slightly in form as a consequence of molting or regeneration,
but without implying the differentiation in question. Again at the seventh stage these

lock spine; p, compound proximal tubercle of crusher claw. Enlarged about 34 times.

claws may appear to the naked eye essentially alike in form and size. Thus, to give
a concrete example, a lobster in the eighth stage, measuring 19.75 milimeters, September
22, showed a rather striking similarity in the forceps, the dimensions of which were as

follows :

Right claw (future crusher): Millimeters.

Length 7

Breadth .. 1.7

Left claw (future toothed forceps):

Length 7

Breadth 1. 4

268

BULLETIN OF THE BUREAU OF FISHERIES.

When these claws are magnified thirty or forty times (fig. 15 and 16) the first steps
in the differentiation of the crushing from the primitive toothed type of claw become
evident. They are expressed by a blunting or rounding off of the sharp points of the
teeth, and a tendency to fusion among those situated at the proximal extremity of both
divisions of the claw. (Compare fig. 21-24.)

We therefore conclude that during the fourth, fifth, and in some cases at least in

the sixth or even seventh stages of the
lobster, both of the big claws represent
the older or phylogenetic type which is
retained as the toothed or lock forceps of
the adult. The chela destined to become
the crusher is a little broader though
not necessarily longer than its fellow, and
its teeth which still show the periodic
sequence are more rounded, as we have
just seen, at the proximal end of the series.
The tufts of sensory hairs are, moreover,
less prominent on the future crushing
claw, as apparent in all the later*stages.

The development of the toothed type
of claw is represented by a series of draw-
ings (fig. 17-25, and pi. xlii) from the first to the ninth or tenth stages, in which the orderly
appearance of the spines can be followed with approximate accuracy up to stage 3, and
with certainty beyond it. The large propodus only is represented in most of the figures.

The spines of the toothed claws are developed in a linear series, and the order in
respect to size corresponds to that of age, or time of appearance. The larger teeth of
the first order are the first to
emerge. They are set at wide in-
tervals and evenly spaced. From

2 to 3 are recognized in the chelae
of the first larva (fig. 17) and from

3 to 5 in the claw of the second
stage (fig. 18). In the third stage
the normal number of primary
teeth are present (fig. 1 9) , although
some of them are very small, and
in the intervals between them are
interpolated rudiments of the teeth
of the second order. In a single series the first trace of the third series of teeth may
be detected also. At the fourth molt (fig. 20) a single period of eight may be com-
pleted by the intercalation of the four small teeth of the fourth order; but the process does
not always stop here, and an attempt, so to speak, is often made at the seventh, eighth,
or at some subsequent molt to introduce a fifth series of 8 teeth, which if completely

Fig. 18. — Outline of corresponding part of big claw shown in figure 17, but in
second larval stage, showing the separated primary teeth, invaginated
claw-tip, and setae, as well as a new spine arising at either end of the
series. Spine 1 of period m now bears the duct of a gland. See figure n.

Fig. 17. — Outline of great claw tip, showing serrate margin of pro"
podus, in first larval stage of the lobster, represented as a trans-
parent object, from glycerine preparation. Note the invagi
nated sensory hairs or seta ( s ), and claw-tip ( t ^), and three
teeth of the first order (1, 1, 1) developing from apex to base
and representing the three primary periods (1, 11, m), indicated
in figures n and 18; also a tegumental gland opening at the
tip of each of the two oldest spines.

NATURAL HISTORY OF AMERICAN LOBSTER. 269

successful would increase the serial number to 16. A few cases are noted of the intro-
duction of a tooth of the sixth series (table 6, no. 8, n&). The process of interpolation
is illustrated in the diagram (fig. 11) up to the usual 8-period stage, which is commonly
attained at the fourth or fifth molt.

Fig. 19 — Outline of corresponding part of great claw shown in figures 17 and 18, but at third larval stage, showing
spines of the second order, sometimes preceded by ducts of glands (d 2a , and d 2b), interpolated between those of the
first, also spur ( sp ) and tip of claw ( t s), both of which arise like the setae, and like the teeth are provided with
glands, the ducts (d t g) of which open at their summits. Compare figure 11.

The first teeth to appear apparently occupy the same plane, but at the seventh
stage, or even before this, the alignment is similar to that of the adult claw, and the
future “lock spine” or tooth (L in all the figures) is readily distinguished by its form and
position.

It is interesting to notice that in all the early larval stages and up to at least the
fifth or sixth molt, each serial tooth is regularly pierced by the canal of a single tegu-

Fig. 20. — Outline of corresponding part of big claw represented in figures 17 to 19, but at fourth stage, showing spines of the
third and fourth orders, and the establishment of a single period of 8, though the identity of the periods in this case
can not be exactly defined. Invaginated claw tip still bears duct of gland (d t g), and the spur (sp) is still invaginated
like a hair.

mental gland (fig. 17-20), which opens on its proximal side and just below the summit.
In some cases the opening of the duct precedes the spine and marks its future position
exactly (fig. 19 d? b). While the serial spines are always developed as outgrowths of
the skin, the tips of the claw (fig. 17-20, t. s.) and peculiar tubercle or spur (sp. in all
figures) originate like ordinary hairs, and like them are always invaginated previous to

270

BULLETIN OF THE BUREAU OF FISHERIES.

molting. a It is to be further noted that as early as the third larval stage and for some
time thereafter the claw-tip, like the tooth, gives passage to the duct of a gland [d. t. g.,
fig. 19-20). I have not found glands of this type in the spines of the adult claw, and
if present in older adolescent lobsters they are successfully concealed by the opacity
of the shell. The adult spines were sectioned, but in all the young stages glycerine
preparations were relied upon. A single tooth sometimes bears the ducts of three inde-
pendent glands, in which case it is probably compound, resulting from the fusion of a
corresponding number of teeth. Rarely a bifurcated duct is seen (fig. 2 pi. xlii), each

Fig. 21 and 22. — Right and left forceps of lobster 24 mm. long, reared in captivity, and 11 months old, in
eighth or ninth stage; seen from above, showing early state in the differentiation of cracker (right) and
toothed claws. Enlarged about 40 times. L, lock spine, as in all figures.

tube issuing from a separate gland, but with common opening at the summit of tooth.
Whether these organs possess any special significance in these parts or not I am unable
to say.

The first step in the differentiation of the cracker claw, as already remarked, is
seen in the rounding or blunting of the teeth, particularly at the proximal end of the
series (see fig. 22 and 24, and especially fig. 25). The teeth appear to be retarded in
growth, and while these remain blunt and irregular, those of the toothed claw become

a The sensory hairs, as already stated, are derived solely from the epidermis, no mesoblast ever entering them, and they are
invaginated with every molt. The claw teeth are tubular outgrowths of the wall of the appendage, and are never invaginated.
The rostrum, as well as at least the tips and terminal spur or tubercle of the propodus, are seen to arise like the setse, and like them
are invaginated during the early molting periods, but they are eventually entered by mesoblast.

NATURAL HISTORY OP AMERICAN LOBSTER.

271

even sharper than before and retain their periodic character. The spines of the lock
forceps are also noticeably larger for a time at least. Then follows a characteristic
process of concentration and fusion in the spines of the future crusher claw (fig. 24, c. s.,
and fig. 25, d.), which eventually leads to the reduction of their number. The crushing
tubercle is thus formed by the fusion of a greater or lesser number of spines, like those
of the toothed claw in the fourth to sixth stages.

In the light of this process are to be explained the “transition forms” which Przi-
bram found to arise in the course of regeneration of the crusher claw, showing the knobs
as fusing masses of teeth. The occurrence of such transitional stages has also been
mentioned by Stahr and Emmel.

In the adult cracker claw (pi. xliii, fig. 2 and 3) the propodus bears two large
and six or more smaller tubercles. The big proximal tubercle (p (L), fig. 25) repre-

Figs. 23 and 24. — Serrate margins of claws shown in figures 21 and 22, in regions marked a and b. and corresponding
to periods ii-iv. Two perfect periods of eight sharp spines appear in the future lock forceps, and interpolations with
fusions of teeth (c s ) in the future crusher.

sents mainly the lock spine of the toothed claw, with the addition of lesser elements,
while the great distal tubercle ( d .) is composed of a fused mass of upward of thirteen
spines, embracing the whole of the third and a part of the second periods. The dactyl
of the crusher also possesses two tubercles of greater size, which close over the intervals
between the “molars” of the propodus, besides a dozen or more small ones, resulting in
each case from the fusion of several spines. There is also a small rounded tubercle on
this segment at its proximal end and below the serial line.

The final differentiations established between the great crusher and lock forceps
are illustrated by a perfect set of typical claws from a hard-shelled lobster which must
have weighed approximately 12 pounds. In all measurements excepting length this
crusher greatly exceeds its fellow, being one-third broader, weighing twice as much (in
the dry shell), and having more than double the cubic capacity. In animals of adult
size the slenderer claw has often a slight advantage in length over the more powerful

272

BULLETIN OF THE BUREAU OF FISHERIES.

cracker, as in this case, and in giants the difference is sometimes striking. The dry shell
of this crusher is so dense and strong that it will bear the weight of a man of average
size without giving way. The measurements of these claws are as follows:

Crushing claw:

Length propodus

Greatest breadth

Greatest girth

Contents

Weight of shell (8% oz.) .

Toothed forceps:

Length propodus

Greatest breadth

Greatest girth

Contents

Weight of shell (4^3 oz.)

inches. . 8^2

do ... . 4^

do. . . . iif^s

.cubic centimeters. . 680
grams. . 235

inches. . 8 %

do.... 3%

do 8yg

.cubic centimeters. . 320
grams. . 116

The armature of this cracker claw (fig. 2 and 3, pi. xliii) is typical and does not
essentially differ from that found in giant lobsters weighing upward of 25 pounds.

Fig. 25. — Armature of right crusher of female lobster 35 mm. long, and at approximately the tenth stage,
showing origin of “molars” by fusion of spines. The proximal tubercle of the propodus (p (L)) is de-
rived from the lock spine, while the distal ( d ) is composed of a fused mass of over a dozen teeth, embrac-
ing the whole of period 11, and part of m. Length of claw 14.5 mm.

As in their case also the blunted end of the dactyl meets the big distal “molar” of
the propodus, which, in the Belfast lobster, is worn flat and is ik* inches long by
1 % inches broad. The dactyl in the slenderer claw is considerably longer, and as
noticed above in mammoth lobsters the toothed forceps tends to surpass the crusher in
length.

Since writing the preceding paragraph I have had the opportunity of reexamining
the New Jersey lobster, which holds the record for size and weight (see no. 9, table 1),
and find that the great claws which here reach the extreme known development of
such organs, conform to the types already described and to conditions met with in mam-

NATURAL HISTORY OF AMERICAN LOBSTER.

273

moth lobsters generally. The cracker claw of this giant is remarkable for its swollen
ovoidal form, its girth being 20 % inches, and for its worn and blunted tips; the blunt end
of the “hand” is even recessive, the tubercular margin being convex as is frequently
noticed in very large animals, and this in spite of the fact that the big molars are worn
nearly flat. The worn-off end of the dactyl strikes about midway on the big distal
tubercle, while the arrangement of the tubercles themselves is typical and essentially
that given above; the propodus showing only two big “crushers,” with one small inter-
mediate and two paired or double proximal tubercles.

In the lock forceps of this specimen the hooked points are broken, rasped, and worn
down, while its serrated margins are slightly convex, as is often the case in the fourth
or fifth stage. The dactyl of this claw presents 7 to 8 primary spines. The huge,
pyramidal lock spine of the propodus is much worn, and the first period distal to this
bears 10 spines, having the formula: 1 + 1 + 2 + 4+2 = 10. Then follows a long and
probably compound period of 17 spines; then a primary spine and several smaller ones
opposite the “spur.” Thus, in this huge claw from lock to spur there are only three or at
most four periods represented, as in all the younger stages hitherto discussed. This again
illustrates the fact that while the procession of spines is constantly “on the move,”
the “dental formulae” for the toothed claw never being identical for any two successive
molts, the losses are so well balanced by the gains that the toothed claw, which attains
its characteristic form from the fourth to the seventh molt, remains essentially unchanged
throughout life.

We have seen how the toothed type of claw, which Stahr considers an ornament
fitted to please the “aesthetic sense” of these animals, has arisen, but the wonder is
not that the teeth are arranged in periods of eight, but that they are developed in order
at all. The problem is similar to that of the orderly arrangement and appearance of
the paired mesentaries of certain coral polyps, and fundamentally the same as that
of the orderly development of the parts of all organic bodies, concerning the mechanics
or the regulative control of which nothing is definitely known.

When we consider the known structure and development of the great claws in
relation of the known habits of their possessor, we find no warrant in considering them
as an “ornament” or in any other light than that of most efficient tools and weapons,
chiefly for defense, for the capture of prey, for rending it in pieces, and afterwards for
handing over the edible parts to the grinding mechanism which begins with the mouth
parts and ends in the stomach. The developmental history of the lock forceps and its
periodic teeth, as narrated above, renders any criticism of Stahr’s fantastic theory, on
the ground of comparative psychology, superfluous.

On the inner margins of the great claws appear certain prominent spines (fig. 2,
pi. xxxvii up. ser., and /. ser.), which are very regular in form and position, but vary
somewhat in number. They consist of an upper series of 4 to 6 stout spurs curved
upward and forward, and a lower of 1 to 3 teeth of lesser size, alternating with the first,
and bent downward and forward. They probably originate from a single series, by
displacement. They are eminently protective, while the proximal and often double
spur on the upper side may act as a buffer when the claw is folded inward. Greater

48299° — Bull. 29 — 11 18

bulletin oe the bureau of fisheries.

274

attention, however, is called to the serrated jaws of the forceps themselves, owing to
the origin of their teeth by interpolation in the way described, and to the periodicity
thus established, but the biological significance of one set of spines may be as great as
that of the other.

VARIATION IN THE POSITION OF THE GREATER FORCEPS.

As was long ago remarked by Aristotle, a it seemed a matter of chance whether the
crushing claw were on the right or left side of the body, but this is not altogether the
case. The large claw occurs about as frequently upon the right side as upon the left,
without distinction of sex, as shown by the following table, in which 2,433 individuals
are recorded:

Table 7. — Showing Variation in Position of Big Claws.

Sex.

Crushing
claw on
right
side.

Crushing
claw on
left
side.

Claws
similar
and of
toothed
type.

Males

562

62S

Females

602

638

Total

1, 164

I, 266

I have shown that in Synalpheus brevicarpus ,b of the Bahama Islands, where the
large hammer claw can be recognized even before the animal is hatched, the members
of a brood are either right handed or left-handed, that is, have the hammer on the same
side of the body. This seems to be a case of direct inheritance from the parents, though
not enough data were collected to settle this point.

Since the issue of that work my earty observations have been extended by Coutiere
and our combined results are tabulated below. c

Table 8. — Showing Position of Big Claws in Broods of Synalpheus.

No.

Great
claws of
mother.

Number
in brood.

Right-

handed

larvae.

Left

handed

larvae.

d3°

Left

Right . . .

2 I

Left

3 1

. .do

. . .do

165

157

o ‘In the Carabi and in the Carcini the right claw is invariably the larger and stronger. For it is natural to every animal to
use its right side in preference to its left. In the Astaci alone it is a matter of chance which claw is the larger, and this in either
sex.” Aristotle: The parts of animals; translated by W. Ogle, London, 1882.

b Herrick, F- H.: Alpheus: A study in the development of Crustacea. Memoirs of National Academy of Sciences, vol.
v. ch. v, 4th mem . p. 370-463 + , pi 1-38). Washington, 1892.

c Couti&re, H.: Les Alpheidae”, Morphologie exteme et interne; Formes larvaires; Bionomie. Annales des Sciences natu-
relies. s6r., Zoologie, t. lx, p, i-iv, 1-560, pi 1-6, text fig. Paris, 1899.

dThe exact number in this brood was uncertain, but all that were preserved were left-handed. No. 1-4 were observed by
the writer, no. 5-8 by Coutiere. No. 1-3 refer to Synalpheus brevicarpus, no. 4-8 to the smah Synalpheus longicarpus which
abounds in the big black Hircima sponges along shore.

NATURAL HISTORY OF AMERICAN LOBSTER.

275

Out of a total of 165 larvae all but 8 were left-handed and 4 of these last are known
to have had a left-handed mother. Four “families” in which every one of the 130
members were left-handed are known in two cases at least to have had left-handed
mothers, the position of the crushing claw not having been observed in the others.
Where the children of the same family vary in this character, it is probable that the
parents or grandparents varied also. However, as I pointed out in 1892, the position
of the toothed or crushing claw is not haphazard in its primary condition, but is pre-
determined in the egg.

In the next section, however, we shall see that in Alpheus as well as in other genera
a remarkable reversal of the position of the big claw may take place, as a result of loss,
so that in the course of life the crusher may shift back and forth, being now on the
right and now on the left side of the body. The question therefore arises whether the
left-handed female (no. 7 of the table), whose 44 children were all left-handed, was
herself left-handed at birth, and secondly, whether, as in the right-handed Alpheus
(no. 5), two-thirds of whose young were right-handed and the other third left-handed,
the shifting of the big hammer claw would influence the inheritance of the children.
These questions can not be answered, but it is suggested that in Homarus as in Alpheus,
where no loss of limbs or other serious disturbance to the processes of growth have
occurred, the right or left handed condition is due to inheritance.

Emmel has recently shown that up to the fourth molt the large crusher claw may
be made to develop upon either side of the body at the will of the experimenter by the
amputation of one claw, thereby, as it were, throwing the greater quantity of energy
into the other for the purposes of growth. This power of control, however, ceases
during the fifth stage, as at all later periods when asymmetry has become established
and when the amputation of either chela does not normally reverse the conditions
present. Emmel concludes that the factors which control asymmetry are correlated
with the conditions of growth from the time of hatching up to the fifth stage. His experi-
ments show that the asymmetry of the big claws of any given animal is not necessarily
due to inheritance, but it would appear that in the normal course of development
heredity played a part, although its initial course may be subsequently changed.

SYMMETRY IN THE BIG CLAWS.

In 1895 (149, p. 143 and pi. 14) I described and figured a variation in the adult
American lobster in which both big claws were similar and of the toothed type. This
variation was exceeding^ rare, as shown by table 7. Only three cases of this abnormal
symmetry were found in this collection of 2,433 lobsters made in the Woods Hole
region by Mr. Vinal E. Edwards, the veteran naturalist and collector of the United
States Fisheries Laboratory.

Since that time several papers have appeared upon this subject by Stahr (258),
Przibram ( 220 ), Caiman (45), Emmel ( 91 , 92, and 93-96), and myself.® The first of

a The account which follows is partly taken from an article on ‘ Symmetry in big claws of the lobster” (no. 155 of bibliography).

276

bulletin of the bureau of FISHERIES.

these writers seems to have found this variation of similar toothed claws much more
common in the European lobster.® The history of development proves, as Stahr main-
tained upon theoretical grounds, that the toothed claw represents the more primitive
and the crushing claw the more modified type. Therefore it seemed natural to infer,
as he did, that the anomalous symmetry in these weapons had been brought about by
loss of a crushing claw and a subsequent reversion to the primitive toothed condition in
the regenerated member which took its place. This would give us a lobster with sym-
metrical toothed claws like the variation described.

The converse of this, or the production of a new crushing claw in place of a toothed
“forceps,” could not occur upon Stahr’s theory of regeneration, and hence he inferred
that my report of a case of similar crushing claws in a lobster was an error. It was
later at first rejected on similar grounds also by Przibram, who regarded the report as
incredible and “worthy of being consigned to the realm of fishermen’s myths.” It
should be added, however, that this objection was withdrawn in a later contribution
(223), and neither Stahr nor Przibram are to be blamed, for my report was based upon
the statement of a fisherman. Still, however great the inaccuracy of fishermen in
biological matters, I have yet to find a lobsterman who could not tell a “club” from a
“quick” claw. It now seems that the maligned fisherman, for once at least, was right,
and he should get his dues even if earlier theories have to be revised, for Dr. W. T.
Caiman, of the British Museum, has described a case of symmetrical crushing claws in
the European lobster (45), and his account is accompanied by an excellent photograph,
which he has kindly permitted me to use (pi. xxix). In all other respects this animal
was a perfectly normal male. It was caught near Stromness, Orkney, and its living
weight was 4 pounds 10 ounces.

In a letter, under date of December 3, 1906, regarding this unique specimen, Doctor
Caiman says:

The correspondence between the two chelas as regards arrangement and size of the crushing tubercles
is even closer than appears on the photograph, where slight differences of color have a little obscured
the shape in one or two points. The differences are no greater than one would expect to find between
the two sides of a normally symmetrical animal. In other respects the chelipeds are practically alike
in size and shape, except that, as seen on the figure, the dactylus of the left is shorter than that of the
right. The basal segments of the limbs show no trace of asymmetry , which is often associated with
regeneration.

To return to Emmel’s paper (93), we find that in two recorded cases, an S^-inch
female and an 8-inch male, “crusher claws” were regenerated after amputation by
autotomy of normal asymmetrical chelae. Emmel further records the capture at the
Rhode Island experiment station in 1895 of a single adult lobster with similar “nipping”
claws. When these were removed by autotomy two similar claws were also reproduced,
but in this instance of the “nipping” type, like those cast off.

While in the usual course of events regeneration of a large cheliped restores the
normal asymmetry of an adult lobster, Emmel has clearly established the fact that it

a Przibram (223) has reported a case of similar toothed claws in a specimen of the Norwegian lobster ( Nephrops norvegicus )
preserved in the Hofmuseum of Vienna.

Bull. U. S. B. F., 1909.

Plate XXIX

Male lobster ( Homarus gammarus ) with symmetrical claws, and both of crusher type. The
first specimen of the kind, living under natural conditions, to be definitely recorded.
For figure of lobster with both claws of toothed type see no. 140 of bibliography, pi. 14.
Stromness, Orkney Islands; weight, 4 pounds 10 ounces. Reproduced from photograph
by Dr. W. T. Caiman.

^ — — LiM flih — ^ - -- -- z**aau&

NATURAL, HISTORY OF AMERICAN LOBSTER.

277

can both produce and restore a condition of symmetry. Both Przibram (221) and
Morgan (203), as well as Emmel, have called attention to the fact that when the crushing
claw is thrown off the regenerated member at first suggests a transitional stage between
the more primitive toothed and the more modern crushing type, but this is not always
the case, for two of Emmel’s lobsters developed similar crushing claws at a single molt.
Emmel’s experiments show that a change in the type of big claw may occur in the adult
lobster, but whether this is to be regarded as a step in the process of complete reversal
of asymmetry met with in the younger stages of Alpheus and other forms described by
Przibram remains to be seen. As Wilson has already remarked, the removal of both
forceps from the prawn, unlike the case of the lobsters referred to, led to no disturbance
in the normal asymmetry of those appendages. In 1901-2 Przibram (221) showed
that in the crabs similar claws could be experimentally produced through regeneration.

To follow the reversal phenomena of Alpheus more closely for comparisons: We
have seen that this shrimp carries a huge “hammer” or snapping claw, which in some
species is as large as the entire body of the animal, and a diminutive claw of more primi-
tive form on the opposite side. Moreover, in the common Alpheus heterochelis of the
southern coast the small chela presents an interesting sexual variation, and resembles
the “hammer” more closely than does the corresponding simpler and more primitive
claw of the female.

A striking example of heteromorphic regeneration or reversal of asymmetry is seen
when the Alpheus “shoots” its “hammer,” or for any cause loses its big claw, as was
discovered by Przibram in 1891. The big claw seems to hold the little one in check,
for no sooner is it lost than the smaller one grows apace and becomes differentiated into
a “hammer” or “snapper,” while, as if in compensation for this change, a diminutive chela
of the primitive type replaces the great claw lost from the opposite side. Wilson ( 284 )
found that in both sexes the small claw, which was regenerated from the stump of the
large one, was always of the simpler female type, and, moreover, that the small chela of
the male was more rapidly changed into the big “pistol” or hammer claw because it was
already further advanced on this line of development than that of the female. When
the smaller claw is amputated, or when the “forceps” are removed from both sides of
the body at once, there is no reversal, a new slender chela or hammer claw taking the
place of the corresponding member lost. Many additional facts have been brought to
light through the experimental studies of Wilson, Brues, and Zeleny.

Przibram (223) has also found by experiment that reversal of the claws takes place
not only in Alpheus, but also in Athanas, Carcinus, Callianassa, Portunus, and Trypton;
that the tendency is most marked in the younger stages, and that it decreases with age.
His results are therefore similar to those obtained by Emmel (9a) in the lobster, where
the experimental control of asymmetry ceases, as we have seen, at the fourth stage.

In the lobster no reversal or compensatory regulation normally or usually attends
the regeneration of any of its appendages. The crushing or the toothed forceps, when
severed at the “breaking plane,” are as a rule replaced by their like in due time after
one or more molts. How, then, are we to explain the anomaly of similar claws? It

278

bulletin of the bureau of fisheries.

seems highly probable that the reversal, which regularly takes place in Alpheus when
its great “hammer” claw is cut off, does actually occur, though but rarely, in the lobster,
or, rather, that a step in the process takes place, there being no immediate compensatory
change to restore equilibrium of the system of which the great claws form a part. Thus,
when a “club” claw is “shot” or amputated by the experimenter, a chela of similar
crushing type is usually regenerated in its stead, but rarely a toothed claw may appear.
There is a change in the appendage, bringing about an abnormal condition of symmetry,
but the process stops here, and we have as the result lobsters with similar toothed claws,
like the specimen illustrated in an earlier work (149).

In like fashion the toothed claw of the lobster is usually replaced in regeneration
by a limb of similar type, as is the rule with Alpheus, but in rare cases a “club” claw is
substituted, and we get a lobster with symmetrical crushing chelae, like the specimen
described by Doctor Caiman. This case is certainly much rarer than reversal from
crushing to toothed claws. There is the possibility that these abnormal conditions of
symmetry may be upset by a compensatory change in the appendage of the opposite
side, but there is no evidence at present that this ever takes place.

When most of the preceding paragraphs on this subject were written I had not seen
Emmel’s valuable paper on the regeneration of crusher claws following the amputation
of the normal asymmetrical chelae in the lobster. Accordingly, the statement that the
case reported by Doctor Caiman was “for the present essentially unique in the literature
of the subject” applied only to the fact of its occurrence in a state of nature or freedom,
the two other lobsters reported by Emmel and referred to above being regeneration
products resulting from amputations.

In discussing the significance of the substitution of the “crusher” for the primitive
“toothed” type of claw, Emmel does not consider that any explanation is at present
possible, either on the basis of “reversal” phenomena or of “compensatory regulation,”
and he thinks that we must be content at present with a record of the fact that sub-
stitution by regeneration takes place. I have endeavored merely to point out the
probability that in such forms as Alpheus and Homarus we are dealing with processes
which are essentially similar.

CHANGES IN THE TOOTHED CLAW AT MOLTING.

The adjustment of the blood supply in the big claws and the adaptation of their
tissues to the process of molting, in the course of which their great bulk of muscles is
pulled through the narrow ring at the base of the cheliped, are described in chapter iv.
We shall now consider the interesting changes in the armature of the toothed claw or
lock forceps, which are expressed at a given molt.

The behavior of the spines of this weapon suggests the movements of a company
of soldiers at drill, and offers a striking illustration of that power of regulative control
which distinguishes living things. The peculiar alignment of the spines of the forceps,
by means of which its serrated jaws overlap, apparently effected by concerted but
reversed movements of the teeth, and the behavior of the large “lock” spine, which
gradually shifts to a position far out of line with its fellows, have already been described.

\5434 243 1

28o

BULLETIN OF THE BUREAU OF FISHERIES.

The armature of the toothed claw of a seventh-stage lobster and that of the eighth
stage from the same individual are given in figures 4 and 5, plate xlii. The formulae for
three typical periods in similar stages of another individual are also tabulated (table 5,
no. na and 11b). It will be seen that five new spines have been gained in the course
of this molt, and that one of them (the second in series in) belongs to the sixth order,
while three have dropped out.

Similar changes were effected in the course of the molt of an adult lobster (lengths
before and after molting, n1^ and 12^2 inches, respectively), and are illustrated in figures
26-29, where the spines are represented in profile and in horizontal projection. The
“dental formulae” are also given (table 6, no. 12a and 126), from which it appears
that five spines have been gained without corresponding loss in the three periods con-
sidered. More interesting changes have occurred at the proximal end of the jaw, where
five characteristic large spines (a-e, fig. 27 and 29) have been retained, but the inter-
mediate smaller groups (/— i) have lost from one to two members in three instances and
in one case have gained two. Spine i has moved toward the lock spine, and bears two
satellites, which seem to be thrown off as buds. The large tooth of the first order in the
proximal period (iv, 1) has also received new recruits upon either hand (in, 4, and iv, 4).

Looking at the jaw as a whole, it has lost 6 teeth and gained 9, the first period alone
having suffered no change in numbers. At the beginning of the molt the jaw was pro-
vided with 49 teeth, while at its close it possessed 52.

This suppression of old and emergence of new teeth probably goes on all the time
in the life of this crustacean, but the changes must be compensatory, for no substantial
losses or gains in the complete armature are finally registered in animals of great age.
It will be observed that new spines often occur in the most crowded places, and it
seems probable that such intercalated members arise as buds from their larger neighbor,
as suggested above. In the earlier stages, however, there is no evidence of budding
growth or division at the surface. As to why in certain parts (groups f-h, fig. 27
and 29) teeth are summarily suppressed, we can only hope that at some future time
light may be thrown on such obscure questions.

Chapter VIII— DEFENSIVE MUTILATION AND REGENERATION.

AUTOTOMY OR REFLEX AMPUTATION.

The casting of the big claws and of some of the smaller legs described as defensive
mutilation, autotomy, or “self -amputation,” is highly characteristic of the lobster.
It is closely associated with the remarkable power of regeneration or replacement of lost
parts, and less directly with the periodical renewal of the shell. These subjects have
opened up wide fields for research, the borders of which we can only touch at a few
points.

The power of reflex amputation is most perfectly developed in the large chelipeds
of the lobster. When this animal is seized by the claws, and struggles to escape, ampu-
tation is likely to occur in both limbs. The animal surrenders its principal weapons,
but may escape with its life. The powers of regeneration are at once enlisted in the
complete renewal of the lost members. Every stage in the process can be found in
animals kept alive in floating cars or in those sent to the markets. Out of 725 lobsters
caught at Woods Hole, Mass., in December and January, 1893-94, 54> or 7 Per cent,
had thrown off one or both claws. The leg is broken off, as we have already seen, at a
definite place, called the “breaking plane” or joint near its base, through reflex muscular
contraction; there is but little bleeding from the old stump, and a new limb soon sprouts
and is regenerated. The slender walking legs are sometimes lost and replaced in a similar
way. Many, if not all, of the appendages, when mutilated or removed, are capable of
regeneration, the time required for the process depending upon the proximity of the
succeeding molt, the vigor of the animal, and the temperature of the water.

In autotomy the five distal segments of the limb are cast off, fracture taking place
in the walking legs at the free third joint, between second and third podomeres, and in
the great chelipeds at the corresponding breaking plane. On the second compound
podomere of the first pereiopod of the adult the suture of basis and ischium is marked
by a fine hairline or encircling groove, free from setse, and it is always in this plane that
disjunction occurs. If the terminal parts of the limb are amputated autotomy of the
remaining stump usually occurs before the work of regeneration is begun. Mutilation
of the claw alone, however, is not necessarily followed by the casting and renewal of the
limb. Parts regenerated in any of the appendages are as a rule similar to those thrown
off, except in the case of the eyes and big claws under certain conditions. The stalked
eye can sometimes be made to produce an antenna-like structure, and while big crusher
claw usually reproduces crusher, and lock forceps lock forceps, this is not invariably
the case, and we occasionally find lobsters with both claws similar, and of either toothed
or crushing type, as described in chapter vn.

Autotomy can be experimentally produced by seizing the animal by its claw or
slender legs, or by stimulating the nerve of the limb directly, the reflex nerve center

281

282

BULLETIN OF THE BUREAU OF FISHERIES.

having been found to lie in the corresponding ganglion of the cord, but if the animal is
anaesthetized it will “forget” to shoot its daw. We have seen that the basis has lost
its muscles, and that the ischium possesses two extensors only; in order that autotumy
should normally occur it would seem to be necessary that the part of the limb distal
to the breaking plane should offer a greater resistance than the traction of the small
extensors of the ischium is able to overcome; ordinarily the clutch of an enemy furnishes
the opposing force required, but since the action is purely reflex, “accidental” disjunc-
tion of a limb which happens to be suddenly opposed in its movements may occasionally
happen. The probable relations of autotomv to the interlocking mechanism of the
coxa and ischium are described in chapter vii.

While no tendons cross the breaking joint in the adult lobster, Emmel (97) has shown
that this is not the case in the larvae, in which he has discovered a transitory muscle of
considerable interest; this muscle originates on the inner wall of the basis, crosses what
is then a free joint, and is inserted upon the inner side of the ischium. It acts as a flexor
during the first four stages of life, begins to dwindle in the fifth stage, and is reduced to
a mass of degenerate tissue in the sixth. It has been maintained that in the lobster
the breaking plane does not represent a lost joint (see no. 255), but that a fusion has
taken place between the third and fourth segments, a statement which is not easily
understood. Thanks to the peculiar interlock of spurs on the first three podomeres,
it is easy to follow the changes which these segments undergo from the fourth stage
onward without difficulty (seech, vii, p. 259), and if any further evidence were needed
to show that the breaking joint, which is functional up to the fourth stage, corresponds
to the articulation of the second and third segments, it would seem to be furnished by
Emmel’s discovery of a missing flexor muscle at this point.

While autotomy does not normally occur before the fourth stage, the limbs are
often snapped off at the joint destined to become the breaking plane. Lobsterlings
occasionally cast a claw at the articulation between the second and third segments which
has the appearance of a free joint; fusion is not completed until the fifth stage, from
which time onward autotomy in its typical form becomes a common occurrence.

An interesting adjustment to prevent excessive loss of blood in the stump of the
refiexly amputated limb has been described by Emmel (97). We have seen, in referring
to his account in another place (ch. vi, p 245), that as the venous sinus crosses the
breaking plane it is divided into two channels by a septum in which are lodged the two
arteries and two nerves of the limb; on the proximal side of the joint the septum gives
off two folds, which are swung out by blood pressure after the break occurs and acting
as valves to the small openings exposed, check the bleeding at once. It would appear
from Emmel’s work that the severed arteries must immediately contract so that their
blood is discharged proximally to the folds or valves which he describes. Whether a
similar adjustment to prevent excessive loss of blood is found in the other appendages,
so far as I am aware, has not been determined. To continue this account further,
when a claw is shot, a short jet of blood is thrown from the stump, but the bleeding soon
ceases, followed by a slight swelling of the tissues over the fresh surface; if the valves
are pressed open the bleeding is resumed.

NATURAL HISTORY OP AMERICAN LOBSTER.

283

Reflex amputation in crustaceans, whether considered in relation to shock or to fear,
or as an independent mechanism, must be regarded as one of the most remarkable
phenomena of invertebrate life. The loss of a considerable amount of tissue is always
a shock to a higher vertebrate, while a lobster in autotomy of both its chelipeds may
give up with impunity one-half the weight-, or even more, of its entire body. In the
higher animals fear may be due to inheritance or it may directly arise through asso-
ciation, by experience. The lobster, indeed, shows fear by hiding or by its hasty retreat
from an enemy, but reflex amputation does not appear to have any necessary relation
to fear. The reflex center of the cord is aroused to activity by a stimulus coming direct
through the nerves of the limb, and not from the brain. We may be sure that the
same center does not at one moment give the order to flee, and at the very next compel
the animal to drop any of its legs. The lobster or crab does itself a grievous injury
automatically in order to escape a worse fate. This kind of reflex surgery thus seems
to be an afterthought of nature, as if an attempt had been made to repair an earlier
mistake, or a compensation, as it were, for having originally endowed the crustacean
with a frame too vulnerable to attack, or with a mind too feeble to successfully cope
with its environment.

RESTORATION OF LOST PARTS.

The power of restoring lost or injured parts through the process of regeneration is
very general throughout the body and appendages of the lobster. It is exercised very
perfectly and promptly in the big chelipeds when thrown off by autotomy at the break-
ing plane, where the process has evidently been favored by natural selection or some
other factor of evolution. Regeneration is also very active in the fragile antennae and
the walking legs. All of these organs are, at the same time, very liable to injury, and
are essential to the maintenance of life by directing the animal to its food and enabling
it to secure it. In conveying this food to the mouth and preparing it for the stomach
the mandibles and other mouth parts are quite as important; the swimmerets also serve
a variety of necessary functions, but all of these structures are far less liable to injury.
Whether there is a causal relation between liability to injury and facility to restore the
injured parts is another question. Morgan has reached a negative conclusion in his
experimental studies on the hermit crab, and concludes that “regeneration is a funda-
mental attribute of living beings.” The question, however, does not depend upon a
single relation; the relations are undoubtedly very complex, and it can not be denied
that in such animals as the lobster the external organs which are most exposed to injuries
of every kind and which are of immediate necessity for the maintenance of life possess
the most active power of regeneration.

Emmel has shown (8g) that the power of regeneration varies at different levels in
the limbs and that even the swimmerets may regenerate more rapidly than the legs if
the latter are cut off but a short distance below the breaking plane. Therefore the rate
of regeneration depends upon the place of injury as well as upon the amount of surplus
energy available at that point.

The regeneration of a large cheli-ped in the fourth and fifth stages is essentially the
same as in the adult. At the moment the limb is broken off there is but little loss of

284

bulletin of the bureau of fisheries.

blood, which coagulates and forms a protective crust over the stump. In a short time a
small white papilla, which represents the rudiment of the new limb, appears in the midst
of the brown, hardened clot. This papilla continues to grow independently of the
molting process, though covered with a cuticular membrane, until a miniature appendage
is formed. The papilla lengthens, and gradually the constrictions which mark the
future joints of the new limb make their appearance. At first colorless, the new
appendage becomes bright, transparent red, with bluish pigment at the constrictions of
the joints. In this stage the limb is surrounded by a thickening cuticle and soon ceases
to increase in size until after the next molt. If autotomy occurs just after a molt, the
appendage will reach a much greater size than if it happens a short time before, but
within the limiting period referred to below. When the molt finally takes place the
new stump becomes very much larger, and now resembles the normal appendage in all
respects except size. With each succeeding molt the normal size is gradually attained.

The large cheliped of the young lobster in the fifth stage may be regenerated in from
15 to 18 days after a single ecdysis, or it may require a month’s time, during which the
animal may pass two molts. The normal size, however, according to Emmel, is not
attained until after the third molt. He also found that by the repeated removal of the
same appendage in sixth to eighth stage lobsters the rate of growth in the mutilated
limb was repeatedly reduced, but the experiment was not carried very far. This
observer has also found that the thoracic legs will not begin to regenerate if removed
immediately before a molt. The limit varies from 2 to 4 days in sixth to seventh stage
lobsters. In more mature animals the limiting period is 16 days at its shortest duration.
Accordingly, if accidents happen shortly before the molt, the animal must wait until this
crisis is over before nature can give any attention to the restoration of the parts lost.
Apparently in this case the energy required to renew the entire cuticular covering does
not leave any surplus immediately available for the growth of new limbs and tissues.
If the tips of the large chelipeds are clipped off, autotomy does not always or usually
occur, and the limb is completely repaired after one molt. If the limb is injured below
the propodus, it is usually cast off at the plane of fracture.

The antennae are very liable to injury, particularly the delicate, sensitive flagella.
Autotomy does not occur in these appendages, but regeneration may take place at any
articulation in the flagellum or stalk.

In the young the whip of the second antenna may be completely restored without
a molt taking place, while in the adult one molt at least appears to be necessary for com-
plete restoration. In the fifth stage lobster, already mentioned, the antennary flagellum
was restored in about 15 days. This appears first as a papilla or bud, which becomes
sickle-shaped and finally coiled so as to resemble a small spirally twusted red wax taper.

The cuticle of the limbs in process of restoration must be elastic and capable of
considerable distension, although the limit of this distensibility is, in most cases, soon
reached.

According to the studies of Miss Reed upon the process of regeneration in the crayfish
{235), the membrane or the inner half of the double fold which remains after autotomy,
and the blood cells beneath it serve to protect the end of the stump, but take no part in

NATURAL, HISTORY OF AMERICAN LOBSTER.

285

the regeneration of the new limb. To summarize briefly her account, the process of
actual regeneration begins in about 5 days after the loss of the original member by an
extension of ectoderm over the opening, which thus replaces the blood plug formed at
the time of injury. Later these same cells secrete chitin and form a thickened disk over
the broken end of the nerve. The ectoderm pushes out into a growing, expanding tip;
its cells become elongated, join the cells of the old nerve, and reconstruct those of the
new one. As the bud grows out, muscles and nerve are regenerated from ectoderm
cells and folds in this layer appear, thus marking out the future podomeres of the new
limb. The folds, which arise as ingrowths of ectoderm, also secrete chitin; they split
to form the folds of the joints and, finally, at their ingrowing ends give rise to the tendons
of the muscles and to the muscle fibers which are attached to them.

Emmel (97) has obtained similar results in working upon the lobster, wherein the
wound caused by autotomy is soon covered by a plate of migrating epidermic cells.
The wall of the limb and possibly its core were found to be epidermic, the old muscle
and connective tissue cells of the stump appearing to contribute little to the new append-
age. Both new nerve and new connective tissue elements seemed to owe their origin
to the epiblast of the regenerative bud.

MONSTROSITIES.

The curious monstrosities that occur in the appendages, particularly in the large
claws of the lobster, have attracted the attention of naturalists from early times. They
were noticed by Von Berniz over 200 years ago, and some good figures of the deformed
claws of the crayfish were published by Rosel in 1755.0 Among the later students of
variation Bateson (79) has shown that in most of the cases of supposed duplication of
limbs in both insects and crustaceans the extra parts are double instead of single, as where
two dactyls are formed at the extremity of the claw instead of a complete claw consisting
of dactyl and propodus. He has also formulated certain principles according to which
supernumerary appendages make their appearance in secondary symmetry. If the
normal appendage which bears the extra ones is a right leg, “the nearer of the extra
legs is a left and the remoter a right.”

The monstrosities noticed in the chelipeds of the lobster are mainly the result
of a secondary outgrowth from one of the two terminal segments. Rarely the appendage
is duplicated or triplicated. In some cases the extra appendages are perfectly formed,
while in others deformation has been carried to excess, resulting in irregular branching
processes or grotesque contortions. Injuries to the claws are excessively common,
while duplication of the parts is rare. Defective or deformed claws, the result of
injuries in different stages of repair, are met with every day by dealers, while thousands
of lobsters may be examined without meeting a single case of repetition or duplication
of parts.

If the tips of the claws are snipped off near the articulation of the dactyl, the lost
parts are restored at the next molt without autotomy taking place. This is called
simple regeneration by Przibram ( 221 ). This restoration is often perfect, but not

“Inseeten-Belustigung, dritter Theil. Nuernberg, 1755.

2S6

BULLETIN OF THE BUREAU OF FISHERIES.

always so. Distortions arise which may have been caused by a pinch and arrest of
growth while the claw was soft or by injury to the stump. In the latter case the
member might be only partially restored, and unequal growth would account for
the defect.

A small budlike swelling is sometimes seen near the apex of either division of the
claw, and it formerly seemed to me improbable that this could be due to a simple
injury since such appearances are rare, while injuries to the big claws must be excessively
common. I further assumed that, given such an outgrowth, a progressive series of
changes might take place with successive molts, the swollen part becoming bifid and
eventually completely divided. To continue the account upon this basis: With the
growth of the animal, the superadded part, whether it be upon dactyl or propodus,
seems to be shifted at each molt farther and farther back upon the claw, and meantime,
in most cases, to undergo fission in a vertical or somewhat oblique plane. This fission
apparently proceeds until one or both of the supernumerary dactyls are entirely
separated. The opposing edges of these become gradually toothed, so that each is
almost an exact copy of the original. According to the principles laid down by Bateson,
the part which is nearer the original joint corresponds with the appendages on the
opposite side, that which is farthest away with those on the same side of the body.
Many cases occur, however, which do not conform to this and apparently to no other
rule (see 749, p. 144-148).

Since the appearance of my earlier work referred to above, the excellent researches
of Przibram {220-223) and Emmel have added greatly to our knowledge of this
subject. The former has shown that in all probability monstrous growths of every
kind result from a regenerative process following upon injury. However, such growths
are comparatively rare and follow only upon injury of a certain kind, or upon an
injury inflicted at a certain time with respect to the molting period, or under certain
conditions of the animal which are not fully understood.

Przibram found that when an injured leg was retained duplication of the part
might arise through a division of the regeneration rudiment, as in vertebrates, and it
was further shown by Miss Reed that when a leg of the hermit crab is thrown off, if the
base is split lengthwise so as to divide the nerve, there often appear two new legs, each
connected with one end of the nerve. It would thus appear that duplication of a limb
is subject to the will of the experimenter, and that duplicated parts may often arise in
nature through an accidental injury to the nerve rudiment. Further, in 1905 Zeleny
(290) obtained by experimental means the regeneration of a double chela in the fiddler
crab. Two cases where duplication of parts of the big claw followed directly upon
injury to the claw itself or to a regeneration bud have been recorded by Przibram {223)]
the first concerned a specimen of Portunus hastatus, which suffered in an aquarium the
loss of both points of its big right claw in an irregular manner, and regenerated within
three months; after molting, the dactyl became doubled, while the propodus was
unchanged. The second case arose through an artificial division of a normal regenera-
tion bud of the last walking leg of a Carcinus moenas. The operation was performed
with fine scissors on May 14, 1901, and after the molt, which occurred on June 2, the
protopodite showed two separated dactylopodite buds. Since this animal died on

NATURAL, HISTORY OF AMERICAN LOBSTER.

287

the day after the molt, it was not possible to test the hypothesis outlined above, of
progressive changes following each molt. Przibram further expressed the belief that
similar claws in the lobster were due to regeneration, since in crabs individuals with
similar claws could be experimentally produced, a view confirmed later by the
experiments of Emmel, already referred to.

Emmel (92) has described three additional cases in which abnormalities have been
artificially produced through the process of regeneration. In two instances similar
crushing claws resulted, and in a third case a triplication of the claw occurred in one
of the walking legs. This adds greater weight to the conclusion that all deformities in
the limbs of these crustaceans, as well as the condition of abnormal symmetry rarely met
with, may arise in nature through the process of regeneration, directed by some injury
or abnormal condition in the nerve end, the regeneration bud, or the growing or
developing limb.

Monstrosities occur in the early and late embryos, and are therefore regarded as
congenital in their origin (see 749, p. 216). It is well known that embryonic or larval
monstrosities can be produced by subjecting the eggs of many animals to unnatural
and unfavorable conditions, and it is possible that the causes which produce a double-
headed larval lobster are similar to those which bring about the duplication of a big
claw in the adult. Perfect twins are occasionally produced from the same egg (see p. 321).

Emmel has also recorded a striking case of the triplication of a big (right) crushing
claw in a 10-inch male lobster taken alive on the coast of Maine. The normal claw was
the smaller and transitional in type, while the two supernumerary claws were considerably
larger and typical crushers. Of these the outermost was an inverted right, with lighter
colored surface uppermost, and the other a normally disposed left. The abnormal
chela was removed by autotomy, in anticipation by the experimenter of some interesting
results at the next regeneration, but to the regret of all students interested in the problems
of regeneration this animal died in September, 1906.

Emmel remarks that if the duplication of the big claws and other similar deformities
which appear in the lobster were congenital in origin, we should expect to meet with cases in
the larvte and the later stages of growth, but after an examination of over two thousand
fourth and fifth stage lobsters not a single abnormal case was observed. Examination
of thousands of larvae have everywhere given the same result.

What was described in the newspaper press as a “lobster pearl” was taken from
a claw of a cooked lobster by Mr. F. W. Denton, of Hollis, Long Island. Through the
courtesy of Mr. Alfred Eno, of Jamaica, N. Y., the writer was able to examine this
interesting specimen, an account of which, with illustrations, has been published (see
157). The “pearl” is a globular body n millimeters in diameter and of the same
creamy tint as the inside of a lobster’s shell, with which it agrees in every physical and
biological character.® It probably represents a freak of the regeneration process fol-
lowing injury to the claw, and a more or less permanent invagination of the skin at a
certain point. It is safe to say that no true pearl can be formed in any arthropod.

a Dr. W. T. Caiman, of the British Museum, writes under date of January 14, 1911, that a similar specimen was received
from a fishmonger in London several years ago, but in this case the body was "embedded in the abdominal muscles of
Palinurus valgaris,” and is now preserved in the Museum of the College of Surgeons.

Chapter IX.— REPRODUCTION.

Since every attempt at the artificial propagation or rearing of animals must be
made in imitation of nature, the more exact our knowledge of the reproductive
life and habits of old and young the more likely are we to succeed. Apart from their
economic bearings, however, the problems suggested are the most interesting with
which the zoologist has to deal. In the case of many animals the facts which lie at
the surface can be gathered and utilized with comparative ease, while in others, as
with the common eel, whose breeding habits baffled naturalists for centuries, oppor-
tunities for making the essential observations are seldom, if ever, presented. In some
respects the lobster belongs in the latter class; its life is spent at the bottom of the sea,
and when confined in aquaria, where alone continuous observation is possible, the normal
play of its reproductive functions is apt to be disturbed. While much attention has
been given to the subject, and many important facts have been learned, there are
certain questions to which a confession of ignorance is the best answer that can be
given. In reviewing the matter in hand we shall endeavor to make it clear whenever
a plausible conjecture is offered in place of well-attested facts.

SEXUAL DISTINCTIONS.

In general form and color the sexes agree so perfectly as to be indistinguishable
to an inexperienced eye when examined from above. The female abdomen is relatively
broader than that of the male in adaptation to the protection and safe carriage of the
eggs, while length for length the male is heavier, this advantage in weight being seen
in his slightly larger claws. Above the 8-inch size, as we have already observed, males
are usually heavier than females of the same length, even when the latter carry eggs.

Upon turning the animal over, the sex is readily determined by a glance at the
swimmerets, the first pair of which is rudimentary in the female, and bears but a single
hairy blade, the endopodite (fig. i , pi. xxxix). This may be considered as an adaptation
for the benefit of the eggs, for were these appendages of normal size they would catch so
many ova at the time of spawning as to make it impossible for a large animal com-
fortably to fold her tail, a difficulty actually experienced by egg-bearing lobsters over
1 6 inches long. The seminal receptacle appears as a bright blue shield wedged between
the bases of the last two pairs of thoracic legs on the underside of the body. (PI. xxxm,
and fig. 4 and 6, pl. xliii.) Its function is to receive and hold the sperm until the eggs
leave the body and are ready for fertilization. Just in front of this organ the oviducts
open close together on the basal segments of the second pair of small claw feet. Each
duct is closed by a valve and faces its fellow with an inclination backward. When
the eggs are emitted from the mouths of the ducts their natural course in the case of an
animal lying on its back would be downward and backward over the seminal receptacle.

288

NATURAL HISTORY OF AMERICAN LOBSTER.

289

Turning to the male and confining our attention for the moment to external anatomy,
we find correlative structures of great interest. The seminal ducts open to the outside
much as do the oviducts, but on the basal segments of the last pair of walking legs.
The openings face the middle line obliquely and are directed backward and downward.
The underside of the tail is armed with a median row of four sharp spurs, which project
downward and backward from the sternal bars of the second to fifth abdominal somites;
in the mature female these protective spines are rudimentary, a condition which certainly
favors the safe storage and carriage of eggs.

In place of the seminal receptacle we find in the male small corresponding wing-
like processes diverging to form a deep V-shaped groove in which rest the tips of the
stylets or modified first pair of swimmerets (fig. 5, pi. xlhi and fig. 1, a, pi. xxxix).
The inner branch of the second pair of pleopods bears a peculiar short spur, and it is
to be noticed that when the swimmerets of the male are directed forward the stylets
meet on midline between the wings of the sterna just mentioned to form an imperfect
archway or covered passage, while in the divergent angle behind rest the short hairy
spurs. That these parts are concerned in the passage of the spermatophores to the
seminal receptacle of the female can hardly be doubted. Their structure and function
will be more fully considered after the several organs themselves have been examined.

THE RIPE OVARY.

The ovaries, or “coral” as they are sometimes called, are immediately exposed
upon opening the dorsal body wall. They consist of two cylindrical rods of tissue
united by a transverse bridge, behind which each lobe gives off a short, straight duct (fig.
1 , pi. xliv). The ovarian lobes traverse about two-thirds the length of the body, extend-
ing from the forward end of the stomach to the third, fourth, or fifth segments of the
tail, and when approaching maturity are of a rich dark-green color. The ripe ovaries
are so much swollen that they fill all the available space in the upper parts of the body.
The bead-like eggs are clearly seen through the thin ovarian wall, and when this is
cut they flow out, if perfectly ripe, in an uninterrupted stream. When the congested
ovary is not mature the loosened eggs stick together and can not be easily disengaged
without injury. A female with eggs approaching maturity can be readily distinguished
by extending the translucent membrane between the tail and carapace, through which
the color of the ovary is at once apparent, but since the eggs can not be pressed from
the unyielding body of the animal, there is no way of telling when these are ripe short
of actual dissection.

During the long period of growth, which leads up to the production of the first
generation of eggs, various changes ensue, which are essentially uniform except for
variations in color imparted by the yolk to the immature ova. After the first generation
of eggs is expelled a normal reproductive rhythm is established, and during each
cycle which follows, from egg laying to egg laying, the ovary undergoes a definite series
of changes, unless the normal rhythms are disturbed by unusual and unfavorable
conditions. A complete change in environment may necessitate a change in repro-

48299° — Bull. 29 — 11 19

290

BULLETIN OF The BUREAU OF FISHERIES.

ductive habits, and it is remarkable how quickly this crustacean can on occasion adapt-
itself to new conditions, as seen in the successful transportation of the lobster 12,000
miles through the Tropics to New Zealand in 1906-8 (see p. 176).

The history of the ovary will now be considered on the basis of the periodic events
noticed above and as they have been found to occur on the coast of Massachusetts.

DEVELOPMENT OF THE OVARY TO THE FIRST SEXUAL PERIOD.

The ovaries (pi. xlv) are first recognized in well-advanced embryos as minute paired
ovoidal masses of mesoblastic cells below the forward end of the heart and close to the peri-
cardial wall. Later they appear as solid rods composed of a wall or capsule and a lining
epithelium. The ovaries do not originate as hollow tubes, but virtually possess a tubular
structure at the time the ripe eggs are expelled by contractions of their muscular walls.
Egg laying is followed by a collapse of these walls and the immediate return of the
ovary to a solid condition. It will, however, be easier to understand the structure
eventually attained by conceiving the organ as possessed of a tubular form, the entire
wall of which is composed of two parts, namely, (a) a capsular layer consisting of invol-
untary muscle, connective tissue, blood vessels and sinuses, and ( b ) a lining epithelium.
Between these parts the blood finds ready access in irregular channels after leaving its
definitive vessels. The ovarian epithelium consists of a basement membrane and epithe-
lial cells from which the eggs and egg follicles are differentiated (fig. 1, pi. xlvi). The
superficial area of this epithelium becomes greatly increased by irregular inwardly directed
folds or invaginations. Through the reentrant sinuses thus formed blood penetrates to
every part of the organ. The egg follicles are eventually composed of a thin sheet of
tissue, the cells of which, as we have seen, are homologous with the ova. These follicles
separate each egg from its fellows, form a medium for the transfer of nourishment to it
from the blood, and soon begin to secrete about it the transparent egg shell or chorion.
Owing to the manner in which the invaginations of the ovarian epithelium arise, the
ova at a certain stage are arranged in irregular, radial and longitudinally directed tiers;
each tier is embedded in opposing sheets of follicular tissue, while each ovum is com-
pletely inclosed, and the largest and oldest eggs are peripheral.

Along the central ridges of the epithelial folds the primitive ovarian cells mulitply
and become differentiated into the future ova and follicular elements which are crowded
or discharged into what corresponds to the lumen of the ovary, or into its central parts.
(Fig. 5, pi. xlv.)

The process of early differentiation and growth of the eggs seems to proceed in the
following manner (fig. 1, pi. xlvi) : Along the crests of the central folds referred to above,
the ovarian cells become columnar and often greatly elongated; each narrow cell appears
to be attached to a corresponding thickening of the basement membrane, which forms
the lining of a blood sinus. To this is due the “pitted appearance’’ mentioned by
Bumpus ( 41 ). The nucleus of a cell destined to become an egg, which lies close to the
basement membrane, swells into a large spherical vesicle, about which a thin layer of
cytoplasm, without boundary wall, may be discerned. Granules of yolk appear almost

NATURAL HISTORY OF AMERICAN LOBSTER.

291

immediately in the cytoplasm, and henceforth the growth of the egg is determined by
additions to the store of yolk, the materials for the manufacture of which are supplied
by the blood. At an early stage the eggs probably multiply by division, and where
they do not immediately break away from the parent epithelium they become elongated
by mutual pressure, so that their long axes are parallel to each other and perpendicular
to the basement membrane. Irruptions of ova, however, always occur at certain points,
so that the young eggs appear in bunches along the crests of the original folds.

The nuclei of those cells destined to form a part of the follicle are easily distinguished
by their smaller size, rod-like form, and by the relation to the young eggs which they
promptly assume. The nucleus or germinal vesicle grows apace and continues to
expand until, at the close of the first year after a given ovulation, it attains a diameter
of one-eleventh millimeter. Rarely two or more nucleoli are developed in the young
eggs; there is usually but one nucleolus and this of large size.

When sections of the ovary are examined, after treatment with the usual killing,
fixing, and staining fluids, we find the nucleoli of all the eggs lying against the nuclear
wall in the same relative positions; that is, at the “bottom” of the nuclei or on the side
which was lowest at the time of fixation. The nucleolus is apparently released from
its suspension in the nuclear reticulum by the action of the fixative employed, and
responding promptly to the influence of gravity, drops like a shot in a bag. The ulti-
mate position of the nucleolus is thus solely determined by the direction of gravity,
and in reference to the egg itself by the position of the tissue at the time of fixation.

The growth of the first generation of eggs is exceedingly slow, occupying from four
to five or more years, during which the ova must derive their nourishment indirectly
from the blood. Swarms of new cells which continue to arise along the axial folds
tend to drive the largest and oldest eggs toward the outer walls, a condition which is
maintained until these ova approach maturity. When the limit of growth is reached
the eggs are dehisced from their capsules, fill the lumen of the ovarian tube, and crowd
the germinal folds and younger eggs of the next generation farther and farther toward
the periphery.

We have already referred to the variable color of the organs during this period of
their growth. Bright yellow, flesh and salmon color, light olive green, with many inter-
mediate tints, are commonly noticed, while after the first eggs are produced, uniformity
in the color of the organs prevails. With rare exceptions, after the first egg laying the
ovary in due time assumes a characteristic light pea-green color and becomes progres-
sively darker with age until maturity is reached.

CYCLICAL CHANGES IN OVARY AFTER THE FIRST SEXUAL PERIOD.

We have finally to consider the changes which the ovary normally undergoes during
each successive reproductive period. After the eggs are laid the collapsed organs assume
a grayish-white tint and appear flecked with green spots — the residual ova which fail
of emission and stick fast in the lobes and ducts. In the course of 36 hours or less the
ovaries are again solid masses with central germogenal folds, the larger eggs lying nearer

292

bulletin of the bureau of fisheries.

the periphery, where the epithelium has become decidedly glandular in appearance.
(Fig. 4, pi. xlv.) These gland-like organs apparently contribute to the growth of
peripheral eggs for a short period and subsequently disappear. Amoeboid cells pass
from them into the eggs, where their nuclei degenerate, giving rise to swarms of fine
chromatin-like granules, which persist for a considerable time. In 5 weeks from the
date of oviposition the gland-like bodies are reduced to shrivelled remnants, of which
later no vestige can be recognized.

While the massive yolk of the eggs is mainly derived from materials drawn from the
blood and laid down at first in the cytoplasmic reticulum, the migratory cells just
described contribute in a minor degree toward the supply, and the glandular follicles
possibly manufacture yolk directly, although the evidence which seems to support this
idea may be wholly deceptive, owing to the presence of degenerative elements.

In the course of 5 or 6 weeks the ovary, flecked with degenerating eggs which failed
of passage and now of a bright orange color, begins to assume a light-green tint. Exami-
nation of the larger ova shows that the pigment, a green lipochromogen, is first formed
in the yolk spheres immediately around the nucleus and thence spreads centrifugally
until it involves the entire yolk mass. In a year’s time, or at the beginning of the
summer following ovulation, the peripheral eggs, while but little larger, are more uni-
form in size and color, and the whole organ presents a characteristic pea-green tint. A
second period of active growth ensues, followed by a second interval of quiescence during
the winter. At the beginning of the third summer after the last ovulation these eggs
enter upon their third and last period of active growth and are soon ready for extrusion.
(Fig. 5, pi. xlv.)

Owing partly to the presence of the egg membrane or chorion, absorption of the
residual eggs at each period of laying is exceedingly slow. After the lapse of 2 years
traces of them can be detected, and the presence of these orange flecks in the ovary of
any lobster tells us conclusively and at a glance that it has already spawned once at
least.

The ripe eggs, as spawning time approaches, lie free in the lumen of the ovary,
which they distend to an unusual size, its elastic walls becoming very thin in consequence.
Maturation may be completed in the ovary itself, but fertilization is possible only after
the eggs have been expelled from the body. The massive yolk is inclosed in a flexible
and transparent shell or chorion, secreted, as we have seen, by the egg follicle or sac,
and by the time the ovum has reached the ducts its nucleus (female pronucleusl has
migrated to the surface. The ripe egg possesses a single membrane only.

DISTURBANCES IN CYCLICAL CHANGES OF THE OVARY.

It is convenient to notice here what the fishmonger in England sometimes calls
"‘black lobsters.” During the summer months the English lobster dealer is said to
examine his stock daily and to cull for immediate sale such animals as show a tendency
to blacken. It seems that whenever females with ripe ovaries happen to be caught
and are either sent to market or kept in floating cars, the normal reflexes which attend

NATURAL HISTORY OP AMERICAN LOBSTER.

293

the reproductive functions are apt to be disturbed. The eggs, instead of being expelled
in the natural way, perish in the ovary, possibly by having their requisite supply of
oxygen from the blood curtailed, and absorption of this inert mass begins, in part at
least, through the agency of the blood. By taking up the green pigment from the eggs
the blood becomes very dark in color, thus giving all the tissues an unpalatable greenish-
black appearance, very noticeable at the articular membranes.

The green color of the eggs, like that of all parts of the integument of this animal,
is due, as we have seen, to the presence of dissolved pigments of a very unstable char-
acter. In consequence of partial absorption and coincident changes in the pigment
which remains, the degenerating eggs gradually assume a yellowish-orange color.
Whether the animal survives these conditions and succeeds in producing another batch
of fertile eggs in due course has not been determined, but the chances would seem to
be wholly in its favor.

While physiological disturbances of this kind are commonly induced by unnatural
conditions, a single case has been observed in which the eggs of an animal recently
taken from the sea were partially absorbed. Degeneration had spread irregularly
throughout the entire organ, which at this stage of the process presented a remarkable
appearance, being dark green, marbled with light lemon yellow. All the tissues
pervaded by the blood seemed to be steeped in a green dye, which the organism was
trying to throw off.

The structure of the ovaries, as outlined, suggest certain questions of considerable
economic interest, such as the age at which sexual maturity is reached, the limits of
the breeding season, and the length of the reproductive cycle or the frequency of
spawning. We shall endeavor to show what light direct observation and anatomy have
shed upon these matters.

PERIOD OF ADULT LIFE OR SEXUAL MATURITY.

The age of sexual maturity varies greatly in individuals, extending over an interval
in which lobsters vary in length from 7 to 11^2 or 12 inches. Out of thousands we
should expect to find here and there one of possibly less than 7 and more than 12 inches
in length coming to maturity for the first time. We may safely conclude that the
majority of these animals are mature when inches long. Very few are with spawn
before attaining a length of 8 yi or 9 inches. In order to test this question traps must
be put down at a certain point, kept there for a long period, and the catch noted day
by day and month after month. This was done in the harbor at Woods Hole, Mass.,
where traps were laid by Mr. Vinal Edwards December 1, 1893, and the daily catches
recorded until July 1, 1894, the conditions as to molting and the presence of eggs being
noted in each individual. A summary of the catch showing the proportion of each
sex and the presence of external eggs is recorded in table 9. During a period of 6 months
1,344 female lobsters were captured, and of these 168 carried eggs; of 249 females
measuring from 6 to 8 inches but 3 bore eggs, while of those under the 9-inch length
but 1 1 were berried.

294 BULLETIN OF THE BUREAU OF FISHERIES.

Table; 9. — Record of the: Total Catch of Lobsters in the Harbor of Woods Hole, Mass.,
from December i, 1893, to June 30, 1894, Showing the Number and Size of Egg-bearing
Females.

Length in
inches.

Number of
males.

Number of
females.

Females
with eggs.

Total.

Length in
inches.

Number of
males.

Number of.
females.

Females
with eggs.

Total.

iolA

133

iolA

103

182

6 -X

104

' 7 14

113

11 4

168

140

308

12%

I:[

143

115

258

124

170

14 K

9V2

9 4

167

184

351

I»3I3

i»344

168

2,657

The reproductive curve, based upon body length, is seen to begin with the 7-inch
lobster and to rise very slowly between this and the 9-inch size.

We do not assume that lobsters are always uniformly distributed, or that had the
experiment been conducted elsewhere the results would not have been somewhat dif-
ferent. Where thousands of lobsters are captured at any point a considerable number
measuring 8 inches or less may be found to have eggs outside of the body, but the
proportion of this number to the total number of animals of the same length captured
in the same place for the entire period will undoubtedly be very small.

LIMITS OF THE BREEDING SEASON.

Much confusion formerly existed concerning the time when the lobsters laid their
eggs. This arose mainly from the fact that the eggs are carried by the females for a
period of 10 months before they are hatched, and because of occasional departures
from the common rule to which the majority conform. The following conclusion was
reached in 1895: “About 80 per cent of spawning females lay their eggs at a definite
season in the summer months, chiefly in July and August. The remainder, about 20
per cent of the whole number, extrude eggs at other seasons, in the fall and winter
certainly, and possibly also in the spring.” While this statement seems to me now to
be in the main correct, I consider it very probable that considerably less than 20 per
cent of the whole number of spawners lay eggs out of season, as was then suggested.
It is not necessary to review the data by which it was definitely proved that eggs are
at least occasionally deposited in winter and fall. The only way to check these results
is to determine the retarding influence of a temperature varying from 67. i° to 32. i° F.
(September to February, Woods Hole, Mass.) upon different batches of eggs laid out
of the usual season. When normal eggs in the egg-nauplius stage, which in summer

NATURAL HISTORY OF AMERICAN LOBSTER.

295

is outlined on the tenth day and well formed on the fourteenth, are found in winter;
when segmented eggs are taken in November, and unsegmented eggs in February, it is
evident that the production of fall and winter eggs is not a unique occurrence in this
animal.

At the western end of Vineyard Sound and in the region about Woods Hole the
greater number of spawners lay eggs during the latter part of July and the first half
of August. The summer spawning for each year lasts about 6 weeks, and fluctuates
from year to year backward and forward through an interval of about a fortnight.
This variation in the time of egg laying is not remarkable, since the period of growth of
the ovarian ova extends over 2 years. Any disturbance of the vital conditions of an
adult female during this period would be likely to affect the time of spawning. The
spawning season in the middle and eastern districts of Maine is about 2 weeks later
than in Vineyard Sound. In 1893, 71 per cent of eggs examined from the coast of
Maine were extruded during the first half of August.

According to the testimony of various observers, the eggs of the European lobster
are generally laid and hatched from July 15 to August 31, in the northerly parts of its
range, including Scotland, the west coast of Norway, and Helgoland. Larvae may
exceptionally appear, however, at the end of June, or even as late as the first part of
October. In the Skager Rack and Cattegat, at the straits of the Baltic, the hatching
period, at least, is about two weeks earlier (see no. 305), while in the English Channel,
at Plymouth, Allen found that the old eggs were hatched chiefly in May and June, and
the new ones laid chiefly in August.

FREQUENCY OF SPAWNING.

The conclusion reached in 1895 that the American lobster as a rule lays her eggs
but once in 2 years having been questioned, the subject was again taken up in 1902,
and more conclusive evidence of the truth of this general statement was given.

It was suggested that “the best way to test the question by experiment would be
to take a female which had recently hatched a brood and keep her alive until the fol-
lowing summer, when the next batch of eggs would be due, in case the spawning period
is a biennial one.” I attempted to try this experiment when, on June 19, 1900, Mr.
Vinal Edwards, acting under my direction, through the U. S. Fish Commission, placed
in a floating car at Woods Hole 36 lobsters from which the old light eggs, when close to
the hatching point, were removed to the propagating boxes. I wished to ascertain
three things: (1) Whether any eggs were extruded in the fall, which, according to the
idea of an annual breeding season, ought to occur; (2) what changes took place in the
ovary during the entire period from summer to summer; and (3) how many lobsters
among those which might survive would lay eggs in the following season, one year from
date.

In order to follow the behavior of the ovary I directed that at the beginning of
each month one of the lobsters should be killed and its ovaries preserved, a proceeding
which Scott ( 248 ), in a paper on the spawning of the European lobster, quoted in another

296

BULLETIN OF THE BUREAU OF FISHERIES.

la.

Ser. 1

Ser. II

2 c

place, criticises as follows: “There is nothing to show that the eggs carried by the
lobsters at the beginning of the experiment hatched out naturally and were therefore
extruded during the previous year.” On the contrary, all were of the class which we
call “old egg” or “light egg” lobsters, which taken in June means that these eggs were
laid the previous summer, and can mean nothing else, unless the rarely occurring “fall”
and “winter” eggs which I have described can reach the hatching point in June, a sup-
position still awaiting proof.
There is, further, no evidence that
the removal of the mechanically
attached eggs from a lobster in
June alters its physiological con-
dition. Mr. Scott says further:
“There was no obvious need to
kill one lobster each month to
discover whether it was going to
extrude eggs or not.” This would
seem to be an obvious conclusion,
but it should have been equally
clear that this step was taken for
another purpose, namely, to follow
the changes which were taking
place in the ovary itself. The con-
dition of the ovary tells us at once
whether growth of the ova is active
or slow, or whether an absorption
of the eggs already formed is going
on. The step was far from need-
less, for after July it proved that
there was no preparation for the
production of fall or winter eggs.
In other words, it showed that in
these animals there was no tend-
ency to produce eggs in each of
two consecutive years, the chief
point in the experiment. It was
impossible to foresee how many of
these animals would die in the course of their confinement or because of it, but had all
of them lived two-thirds of the total number at the start, or 24, would have had a
chance to spawn in 13 months from the time the experiment began.®

2a,

3 a,

Fig. 30. — Diagram to illustrate growth in a single generation of lobster’s
eggs during a period of nearly 3 years, from an initial stage in ovary to
time of hatching. Ser. 1, internal or ovarian eggs; Ser. 11, external or at-
tached eggs. 1 a, ovarian egg immediately after egg-laying; 1 b, the same,
15 days after; 1 c , the same 42 days after; 1 d, the same 1 year after; 2 a, the
same in second growth period, 1 year and 10 months after egg-laying; 2 b,
fresh laid egg; 2 c, “strictly” fresh, but removed from ovary or duct; 3 a,
last period of growth in shell, or egg-embryo about to hatch. Sizes de-
duced from averages of 10 eggs in nearly every case. Enlarged about 20
diameters.

a The experiment would have been more satisfactory if the directions, which were as follows, had been carried out: “ Preserve
the ovary of one lobster the first day of each month from July to December. If the number of lobsters should warrant it, con-
tinue to preserve the ovaries of one animal from January 1 until July. If, however, the remaining lobsters are few in number,
and do not stand the confinement well, keep all as long as possible, preserving the ovary of each one that dies. * * * In case
the lobsters die rapidly in late summer or early autumn, preserve ovaries of those only which die, giving the date.”

NATURAL HISTORY OF AMERICAN LOBSTER.

297

By means of the animals killed it was shown that from June 19, 1900, to May x, 1901,
during a period of 10 months and 12 days, the ovaries had undergone a slow and gradual
growth, a very important fact, which, if the conditions of growth were normal, is strong
evidence that in the American lobster annual spawning is not a usual occurrence.

It was further demonstrated that the ratio of growth of the ovarian eggs for stated
periods implied a reproductive cycle of 2 years. (Compare fig. 30.)

In conclusion we found that the theory of biennial spawning is supported: (1) By
the statistics of the fishery; (2) by the anatomy of the ovary of the adult female taken
at different seasons; (3) by the ratio of growth of a given generation of ovarian ova
for stated periods; (4) by observation on animals kept alive for long periods; and (5)
by the evidence of the rapid growth of ovarian eggs of spawners for any given year
during the height of the breeding season.

Any rule to which the majority conforms may be expected to have exceptions.
A lobster may exceptionally lay eggs in two consecutive seasons, and it is possible that
in some cases the normal biennial period may be even prolonged.

When the preceding paragraphs were written I had irot seen a paper of Appelof
(6) in which he confirms the theory of biennial spawning in the European lobster by
an experiment conducted on a larger scale at the fisheries station at Stavangar, Norway.
His statement is as follows:

Since the matter (the question of spawning) had not been decided by experiment, I selected 100
lobsters, which were kept in a natural basin in the neighborhood for this purpose. It can now be main-
tained with complete assurance that in fact 2 years elapse between each egg laying. “

As already seen, a number of spawners, probably a very small proportion, lay out
of season, in fall and winter. How can we account for these exceptional cases? An
experiment tried by Mr. Cunningham (6j) in the summer of 1897, on the European
lobster, suggests an answer to the question. At Falmouth, England, five female lobsters,
bearing external eggs which were nearly ripe, were placed in a floating box during the
summer. After their ova were hatched these females were kept confined with two
males until after October 14, when one was found to have newly spawned. This proves
that it is possible for the European lobster to produce eggs in two successive years,
but it does not prove that this is the common habit of the species in European waters.
It also strongly suggests that these October eggs may correspond to the fall and winter
eggs occasionally produced in the American form. By accelerated growth of the ovary
the ova might be laid in fall or winter when not normally due until the summer fol-
lowing. Under such circumstances the ovarian eggs would come to maturity in 15
instead of 23 months. It would be interesting to know when these autumnal eggs
hatch. The suggestion which we formerly made that they do not give rise to regular
summer broods should be withdrawn, for it seems to us now that more confirmatory
evidence is required before we can accept the statement that the young of the American
lobster are ever hatched in the sea outside the period embracing the months of May,
June, and July.

o In referring to later experiments conducted at the lobster park, at Kvitingso, Appellof remarks: “The conclusion that
the female lobster on the west coast of Norway normally lays its eggs only once in two years, I later found year after year to be
completely confirmed.” (See 305, p. 23).

298

bulletin of the bureau of FISHERIES.

A later notice of the annual spawning of the European lobster after transplanta-
tion to artificial ponds in New Zealand has been given by Anderton (5), whose observa-
tions on the molting and breeding habits of this animal under a complete change of
environment are most interesting and are referred to in various parts of this work
(see p. 302). At the time of writing, when his observations had extended over 3 years,
several of the lobsters had laid two batches of eggs, and one, which bore attached eggs
at the time of shipment, was known to have spawned three times in 3 years and 7
months. The record for the latter lobster is as follows:

Arrived with a few eggs still attached, January, 1906.

First molt, in absence of male, January, 1907.

Second molt, followed by copulation, November 21, 1907.

First spawning under new conditions, January 24, 1908.

Hatching of first batch of eggs, November 23 to December 28, 1908.

Second spawning; date not determined, but before March 12, 1909.

These animals were confined in small ponds with concreted bottom, and regulated
tidal flow, and were regularly fed and skillfully cared for. It is interesting to notice
that while the seasons are reversed in the southern hemisphere, the local range of
temperature in New Zealand is similar to that at bottom of Vineyard Sound, Massa-
chusetts, the lowest average temperature of 30 C. (37!° F.) being recorded for July
(compare p. 182), and the highest average of 130 C. (551 0 F.) from December to
February.

An interval of 65 days ensued between copulation and spawning, and the fosterage
period from egg laying to the hatching of the first young was 10 months to within a
day. While it can not be maintained that these novel conditions give the usual spawning
habits for Homarus gammarus until similar results are obtained within its natural range
(compare Appellof’s experiments, given above), they show that the lobster is remark-
ably plastic and able to withstand considerable change when directed by skillful hands.

NUMBER OF EGGS PRODUCED.

The freshly laid eggs are of a dark green, almost black hue, when seen in mass,
and somewhat irregular in shape, but they soon plump out and become nearly spherical
or ovoidal in form. As the eggs develop they increase in size, become elongated, and,
owing to the gradual assimilation of the dark yolk, lighter in color. (Compare fig. 33, a b .)
This is most noticeable toward the close of the period of development, when the phrase
“old” or “light” egg lobster is commonly used by fishermen to distinguish them from
the “black” egg lobsters, which have more recently spawned.

The fresh egg measures approximately ^ inch in diameter (1.5 to 1.7 mm.) and
weighs g-oVo ounce or gram. A fluid ounce of eggs weighs about 1 ounce avoir-
dupois. The number of eggs laid is proportionate to the volume of the ovary and of
the bodv, and varies from about 3,000 to nearly 100,000 in animals from 8 to 19 inches
long.

NATURAL HISTORY OF AMERICAN LOBSTER.

299

Table 10. — Production of Eggs.

Length ilobster.

8 inches . . .
8J4 inches .
8M inches .
8K inches.

9 inches . . .
9 inches .
gYz inches .
gY inches .

10 inches . .
10K inches
10Y inches
10H inches

11 inches . .

1 1 >4 inches
nx/2 inches
11% inches

12 inches . .
12% inches
12^ inches
12K inches

Smallest
number
of eggs.

Largest
number
of eggs.

Average
number
of eggs.

Number of
lobsters
examined.

Length of lobster.

Smallest
number
of eggs.

Largest
number
of eggs.

Average
number
of eggs.

Number of
lobsters
examined.

3-045

9- 135

4, 822

13 inches

6, 090

48, 720

28, 610

321

6, 090

7, 612

6, 851

13 inches

24,360

48, 720

33,495

6, 090

9. 135

7, 105

13K inches

42, 630

42,630

3.045

i8, 270

7,902

143

14 inches

6, 090

85, 260

36, 960

426

6, 090

12, 180

9,083

14H inches

21,315

60, 900

42, 968

3.045

20, 792

9. 297

241

15 inches

12, 180

97,440

46.524

280

15% inches

3.045

24,360

io,555

514

15K inches

24,360

97,440

53,795

6, 090

22,838

11, 622

15^ inches

48, 720

54,810

50, 750

3.045

36,540

12,905

532

16 inches

24,360

97,440

57, 146

103

3.045

48. 720

15, 410

568

16 Yt inches

36, 540

85, 260

66,053

6, 090

25, 882

17, 102

17 inches

12, 180

85, 260

63,336

3.045

42,630

18,668

307

17M inches

60, 900

73,080

64, 960

12, 180

24. 360

17,993

18 inches

60, 900

91,350

77,430

3.045

54, 810

2I.35I

414

19 inches

54, Bio

91,350

77,647

18, 270

27,405

23,396

9. 135

42,630

24, 812

156

Total number examined

4,645

18. 270

42.630

26, 390

In table 10 (reproduced from 749) we have given the smallest, largest, and aver-
age number of eggs removed from the bodies of 4,645 individuals. These animals were
“old” egg lobsters and were caught in Vineyard Sound and vicinity from April to
June. The numbers were determined as a basis of 6,440 eggs to the fluid ounce. These
tabulated results show great variability in the number of eggs borne by individuals
of the same length, which may be attributed in part to loss of ova, but more to varia-
tion in the period of sexual maturity. Thus in 514 lobsters of the 10-inch length the
number of external eggs varied from 3,045 to 24,360, with an average of 10,555. For
the 12-inch size the corresponding numbers were 3,045, 54,810, and 21,351. We have
seen that the period of sexual maturity is exceedingly variable in different individuals
and that one animal may lay its first batch of eggs when 7 inches long, while another
may not rear a brood until its body is 5 inches longer and has increased greatly in vol-
ume. The phenomenon is not remarkable in view of the slow growth of the ova, but
it is important to recognize the fact.

Consideration of the average number of eggs produced suggested a general tend-
ency which was expressed as follows: The number of eggs produced at each reproductive
period tends to vary in a geometrical ratio, while the lengths of the animals producing
these eggs vary in an arithmetical ratio. The average production in lobsters 8 inches
long being 5,000 eggs, the average product for lobsters 10 inches long would be 10,000;
for the 12-inch length, 20,000. This high rate of production is not maintained beyond
the length of 14-16 inches. The lobsters with the largest number of eggs measured
from 15 to 16 inches in length and carried upward of 97,000 eggs, which measured
16 fluid ounces and weighed nearly a pound.

Tataste ( 777 ) in a critical paper on that section of my earlier work dealing with
the fecundity of this animal observes that the number of eggs carried by the lobster
at any given time should be proportional to the volume of the body or to the cube
of its length. If N represents the number of eggs carried, l the length of the animal,

300

bulletin of the bureau of fisheries.

and k denotes a constant, according to Lataste, the relation of these quantities would
be expressed by the following equation:

A' = kP;

Whence k = ^.

He has drawn up a table (based on table 15 of 149), from the data of which he
deduces the cubes of lengths, the ratios of the average number of eggs to cubes of length
( k ), and the means of these ratios.

In the lobster the reproductive powers are manifested suddenly at a certain age,
after which they increase steadily, reach a maximum, and then presumably slowly
decline. Accordingly during the first period only does the fertility increase proportion-
ately to the increasing volume of the body, as expressed in the equation given above.

We have no definite information upon the duration of life, or decline of rate of
growth in these animals. It is certain, however, that the renewal of the shell is
quite as necessary for the continuance of life as of growth, since in the course of time
death would result were not the injured and abraded shell restored. In higher animals
the skin and at least some of the tissue cells are being continually renewed throughout
life, while size limit of the body is early attained, and it is not likely that a dense and
heavy shell like that of the lobster could be sloughed without increase in the size or
volume of the body. The decline in sexual vigor may therefore result from the tax
which molting continues to levy upon the capital stock of energy at every period of
life. According to Lataste: k = f (t), k being a function of age which has no real value,
except as it is confined within certain limits.

In conclusion, we wish to observe that upon the principle of correlation of parts
the ratio of the number of eggs to body length should correspond in a general way to
the ratio of the volume of eggs to the total volume of the body were the latter a con-
stant quantity, but owing to the frequent loss of the great claws this is not accurately
represented by the cube of the length. All that we can say is that in the long run
there is a tendency to produce in such a ratio, but the physiological condition of the
animal is an inconstant and indeterminable factor. The high birth rate of the lobster
teaches us to expect a correspondingly high death rate, a subject which will be later
considered.

BREEDING HABITS AND BEHAVIOR IN CRAYFISH.

The breeding habits of lobsters, so far as they were then known, were described
in 1895. Since that time a number of important facts have been ascertained, but
our knowledge of the subject is still defective at many points. The behavior of the
American lobster at the time of pairing and extrusion of the eggs has probably never
been witnessed in a state of nature, and certainly but seldom in any of the higher Crus-
tacea. We have had more or less circumstantial accounts from Chantran, Ishikawa,
and Cano, regarding the time and .process of egg laying in the crayfish, shrimp, and
crab. The pairing habits and process of laying the eggs in the European lobster have
been described by Anderton and Scott, as will be noticed later, while a remarkably

NATURAL HISTORY OF AMERICAN LOBSTER.

301

full and accurate account of the habits of the American crayfish during the breeding
period has been given by Andrews.®

Since the activities of the breeding crayfish are without doubt similar in some
degree to those of the lobsters, and since they are at present far better known, I shall
now give a summary of the instinctive acts and events in Cambarus for the period in
question, drawn entirely from the work of Andrews referred to above.

Pairing in Cambarus affinis takes place in spring (February-April) and fall (October-
November). The male catches the female by the antennae or about the head, rolls her
on her back, seizes her by the claws, stands over her body, and holds her in this position
from 1 to 10 hours, during which time the sperm is transferred to the annulus or sperm
receptacle on the ventral side of her thorax. This process may be repeated by “either
male or female,” both of which are in hard shell.

The male holds with his big forceps all the claw feet of the female in a bunch on
either side, her abdomen being coiled under his, which closely presses it, he meantime
supporting with his left or right fifth leg the abdominal appendages which are to transfer
the sperm to the annulus*. The first two pairs of abdominal legs or modified pleopods
of the male are directed downward and forward against the ventral surface of the thorax
of the female. Since the pleopods tend to lie flat against the body, they thus fold or
close upon the the fifth leg, which stops them, forming a rigid support, and at the same
time giving them the necessary elevation. The male then presses close upon the female
so that his pleopods are directed toward the annulus and are forced into it, where the
sperm is deposited. Spines on the legs of the male further tend to hold the pair firmly
interlocked. Cambarus affinis has a prominent spine on the third joint (ischium) of
the third pair of chelipeds, which fits into the base of the fourth pair of legs of the female.
Spines or hooks of this character are wanting in the lobster. Thus rigidly interlocked,
the transfer of sperm goes on slowly and may last for hours.

The vas deferens of the male is protruded or evaginated, as may be readily observed
in all copulating males, forming a soft translucent double-walled tube, the lips of the
opening being tightly closed. This evaginated duct fits in the groove which passes
down the outer side of the first pleopod, and serves to conduct the sperm towards its
tips. The appendages are rigid, sharp-pointed tools which are inserted into the
annulus, and against which the modified second pair of pleopods are closely pressed.
Sperm issues from the ducts as in the lobsters (compare fig. 2, pi. xliv) in long vermicelli-
like paekets, or gelatinous capsules known as spermatophores, and guided possibly by
the second pair of pleopods, passes slowly down the groove of the first pair to the recep-
tacle or chamber of the annulus. The female is remarkably passive and appears as if
dead, while the excitement of the male is marked.

While the spermatic receptacle of the lobster (pi. xxxm and fig. 4 and 6, pi. xliii)
corresponds in function to the annulus of Cambarus, the latter appears to represent only
the unpaired wedge-like middle piece of the former. The development of the seminal
receptacle in the lobster proves that the middle piece in this animal is the anterior

“Andrews, E. A. Breeding habits of the crayfish. American Naturalist, vol. xxxvm, p. 165-206, fig. 1-10. Boston, 1904.

302

bulletin of the bureau of fisheries.

section of the sternum of the eighth thoracic segment. The divergent wing-like processes
in front of the annulus in the crayfish evidently correspond to the convergent wings,
which are the modified sternum of the seventh thoracic somite, and which, united with
the middle piece, form the elastic lips of the shield-shaped receptacle in Homarus
C St • XIII, fig. 4).

The laying of eggs in the crayfish may not occur for some weeks after sexual union,
and as Andrews remarks, some protection such as the annulus affords is necessary, since
sperm can not long survive exposure to water.

PAIRING HABITS IN THE LOBSTER.

Both Boeck ( 24 ) and Fraiche ( iog ) have referred to the union of the sexes in the
European lobsters as if they had witnessed the act, but the errors which they exhibit
tend to discredit their statements, however brief. Fraiche remarked that copulation
in both the common and Norwegian lobsters took place in fall (October and November),
and in the case of the former that it was extended into winter. “As with the crayfish,
the sexual act is accomplished belly to belly, and so closely 'and firmly do they clasp
each other, that, if taken from the water at this period, it is with difficulty that they
can be separated.”

But the only reliable observations under this head have been made by Anderton (5),
of the Marine Department of New Zealand. The sexual act was noticed on a number
of occasions among the European lobsters kept under observation in small artificial
ponds. The general succession of events was as follows: Molting in early summer
(November and December), followed in the course of a few hours by coition between a
soft female and a hard male, and by the laying of eggs about two months after this
event.

One of the female lobsters kept under observation by Anderton molted on Novem-
ber 21, at 3 p. m., and lay for some time beside her cast shell. “Two hours afterwards,”
to continue his account, “it was seen roaming round the pond and frequently approach-
ing the various shelters, returning regularly and fearlessly to a shelter containing a large
male. On approaching the entrance to this shelter the large claws were extended in a
direct line with the body and the antennae were thrust within the shelter. After a few
moments the rostrum of the male appeared, the female meanwhile rapidly whipping
her antennae across the now projecting rostrum of the male, which in turn showed increas-
ing signs of excitement, the antennae being whipped very rapidly over the female in the
same manner. After an interval of perhaps a minute the male gradually withdrew
from his shelter, the female at the same time turning over on its back. Coition took
place at once, the act occupying only a few seconds, the male retiring at once to its own
shelter and the female into another. The following day both were observed to be living
in one shelter, and they continued to do so, on and off, for several weeks.”®

a In reply to certain specific questions regarding the pairing of lobsters, Mr. Anderton has kindly written under date of
August 2i, 1910, as follows: “ The female lobster after casting does appear to seek out a male as soon as the distressing effects of
molting have somewhat worn off. Male and female have frequently been observed living in one shelter for some days and even
weeks after coition. The act of coition is very brief, and will not occupy more than half to a whole minute. They copulate, as
you express it, “belly to belly,” and head to head. The large chela? do not come into use during the act so far as I have observed.
The female voluntarily turns over almost completely onto her back, the excited male completing the process for her.”

NATURAL HISTORY OF AMERICAN LOBSTER.

303

Three other cases of copulation were witnessed, and in every instance between a
soft-shelled female and a hard male and always within a few hours after the female had
cast. In one instance when the water in the pond was run off the body of the male was
left partly exposed. I have already noticed two cases in which the American female
lobster was impregnated when in the soft condition and when she also bore eggs; but
there are other facts which show that molting is not necessary for the impregnation
of the female. In the case of the American species we have found females of all sizes
from 8 inches and upward in length impregnated at all times of the year, and the adult
female lobster when taken from the sea, in whatever condition of shell, is likely to have
her receptacle well supplied with sperm, even when preparing to molt. On the coast
of Massachusetts in June and July I have found lobsters with newly laid eggs and a
lobster with brood just hatched and about to shed, with receptacles full of sperm, which
was in the first instance certainly, and in the last probably, newly acquired, and when
the shell was hard. We know that the sperm is endowed with great vitality; that it
can endure for months, and possibly for years. It is further probable that copulation
is more or less indiscriminate, and more than one union is sometimes necessary to secure
the fertilization of a given hatch of eggs.

Pearce “ has presented strong evidence to show that crayfishes have no power of
discriminating sex, his conclusions being based upon Cambarus blandingi acutus Girard,
C. diogenes Girard, and C. virilis, observed in confinement. “The male,” says Pearce,
“tries” every crayfish which it meets, whatever the sex, a female instinctively remaining
passive, while a male attempts to escape. The sexes meet by accident in the course of
their random movements in the search for food. Males were found to even copulate
with dead females, and in one instance with a female of another species, when the male
stylets were inserted in the usual way in the copulatory pouch or annulus.

After taking into account all the facts at present known it seems highly probable
that the lobsters are actuated by similar instincts when breeding and that they possess
no greater powers of discrimination.

The probable method of transfer of the spermatophores is considered in a later
section.

PREPARATION FOR EGG LAYING-CLEANING BRUSHES IN THE LOBSTER.

Preparatory to laying, the female Cambarus, as Andrews points out, retires for a
number of days to the dark corners of her abode and is busily engaged in cleaning the
under side of her abdomen for the reception of the fresh cargo of eggs. Her attitude
and behavior in this instinctive act are peculiar. Standing as upon a tripod on the
tail fan and the tips of the great claws, with her body raised high above the ground, she
picks, brushes and scrapes every particle of dirt from the swimmerets and under surface
of the tail, using chiefly the last pair of walking legs, the modifications of which, espe-
cially in the last two joints, render them very effective, combining as they do in one
instrument the advantages of pick, comb, and brush.

® Pearce, A. S. Observations on copulation among crayfishes, with special reference to sex recognition. The American
Naturalist, vol. xi.ni, p. 746-753. New York, 1909.

304

BULLETIN OE THE BUREAU OF FISHERIES.

The brush-picks of the lobster, especially those on the last two pairs of ambulatory
legs, resemble similar instruments in the crayfish, as described by Andrews, and there
can be no doubt that they serve a like purpose. That they are used as cleaning brushes
has been often observed, but no one has yet studied the behavior of the lobster in the
critical period before egg laying is accomplished.

Nevertheless I have recorded an observation (149, p. 47) which, read in the light
of the foregoing account, suggests that the lobster has the cleaning instinct also and
carefully prepares her abdomen for the reception of the ova. In two cases which I
had been watching the lobsters laid their eggs in aquaria, and then industriously picked
and scratched off nearly every one of them in the course of a few days. Now, these eggs
were all of small size and the ovaries did not give up more than a third or a half of
their contents. Under these conditions it would not be surprising to find the attunement
of the instincts at fault. Interpreted in this way, the lobster by cleaning off her eggs
was only preparing herself for the reception of the ova which still clogged the ovary.

In the lobster the terminal joint or dactyl of the last pair of legs (cl. br., fig. 4, pi.
xxxviii) is developed as brush and pick, there being no comb on the under side. It is
cone-shaped and traversed from apex to base by three nearly equidistant rows of hairs
or setae, those of the upper row being long, dense, and serrated. The subterminal joint
bears three conspicuous tufts of saw-tooth hairs, quite similar to the “scouring brushes”
described for the crayfish. In place of the strong spines or picks on this segment of the
Cambarus is a single blunt spur almost concealed by the brush of hairs in the lobster.
Just above it, near the base of the line of long dense setae is a rudimentary comb or
short linear series of spines.

If the short process which bears two spurs or picks in Cambarus were extended, it
would form, as Andrews suggests, a double claw or forceps similar to those of the smaller
chelate legs. In this case, however, the chelae would all have the same relative posi-
tions or work in parallel planes. In the second and third chelipeds the claws work
up and down, or in a nearly vertical plane, on the hinge joints. The great claws, how-
ever, have undergone a twist or torsion, in consequence of which their inner or anterior
surfaces have become their lower sides. (See p. 257.) The dactyls consequently face
and open inward, working in a horizontal plane. Now, the terminal segments of the
last pair of legs have suffered a backward rotation or twist, in consequence of which their
anterior surfaces are directed obliquely outward. If this limb were chelate, the dactyl
would move obliquely outward and backward instead of upward, as in the smaller
chelipeds, or inward, as in the great forceps.

In the lobster the torsion of the two terminal segments of the fifth pair of walking
legs has gone a step further, so that the comb and spur of the dactyl, instead of being
on the lower and anterior side of the limb, as in Cambarus, are upper and hindermost
in Homarus, and, further, they no longer lie midway between the hinges of the joint, as
in the crayfish. The torsion and other adjustments in the fifth pair of legs in the lobster
evidently fit them for reaching and brushing the swimmerets and under side of the tail.

NATURAL HISTORY OF AMERICAN LOBSTER.

305

EGG LAYING.

On two different occasions, as already related, lobsters which I had under observa-
tion laid eggs in aquaria, in the night or early morning. These eggs were fertile and
normally fixed in each case, but the extrusion was not complete, and the instincts of
the female did not run their normal course. In the absence of any direct observations
on the laying of eggs in the American species, the following account of the spawning of
the European lobster, given by Scott (248), has a special interest:

The lobster turns onto its back and by the aid of the two large claws and ridge of the abdomen
makes a tripod of itself, the head being considerably higher than the posterior portion. The abdomen
is then strongly flexed, forming a pocket, and the setae on the edge of the abdominal segments make the
space along the sides perfectly tight. A A-shaped opening into the pocket is formed by the telson and
the sixth abdominal segment. This opening, when the abdomen is flexed, is slightly posterior to the
first pair of swimmerets. The eggs then flow from the two genital openings in a continuous stream, one
at a time, and pass along at the bases of the last walking legs and into the opening of the “pocket. ”
The course of the eggs into the “pocket” is further assisted by a constant pulsation of the first pair of
swimmerets, causing an indraft, which carries them rapidly inside. None of the eggs are lost on the
passage from the genital openings to the “pocket” unless the lobster is disturbed. As the eggs leave
the oviducts they become covered with an adhesive substance which causes them to stick together
and to the swimmerets. The period of oviposition in the lobster under observation was just over four
hours. Half an hour after the eggs had ceased to flow the lobster righted itself and walked into a comer
of the tank, eventually getting into a nearly perpendicular position, with the head downward. It
remained in this position for the rest of the day. Next day it was walking about the bottom of the tank
in the usual way of a berried lobster. That the adhesive power of the eggs was imparted to them before
leaving the oviducts was proved by collecting some just as they emerged from the genital openings.
When these samples were placed in a glass of sea water and collected into a heap , they all became attached
to one another and also to the glass. Moreover, the adhesive material only remains soft for a short time,
as when the individual eggs were isolated and prevented from adhering upon the glass it was found
that at the end of half an hour the adhesive property had entirely disappeared.

ARRANGEMENT AND DISTRIBUTION OF EGGS AND THEIR ATTACHMENT TO THE BODY.

Ishikawa, who watched the prawn Atyephyra lay her eggs in an aquarium, says that
the act is performed in the early morning, and that it is preceded by a molt the night
before, an order of events which has been often noticed in the higher Crustacea. The
eggs were “almost roddike” when they came from the ducts, and were laid down in an
orderly manner, the anterior swimmerets receiving the first, while those deposited later
were driven backward by the last pair of thoracic legs. The abdomen was incurved
to form a pouch during the process, and the thoracic legs as well as the swimmerets
and their corresponding segments were in constant movement.

In the lobster the ova adhere principally to certain setae of the appendages of the
five anterior segments of the abdomen (pi. xxxix), and since hairs are absent only
from the articular membranes of this region, they become bunched about the stalk of each
appendage, and extend over the sternal bar and inner (epimeral) wall of the correspond-
ing somites. In a full-berried female the swimmerets are embedded in a solid mass of
eggs up to their branches, comparatively few being fixed to the free blades, and these
48299° — Bull. 29 — 11 20

3o6

bulletin of the bureau of fisheries.

only to their inner or proximal ends. The eggs, however, are so completely adherent to
one another that if every hair were severed the entire cargo would float off in a single
mass. It should be noticed that the stalks of the swimmerets are inclined inward
toward the median plane of the body, and not away from it as in the thoracic region,
and also that three tufts of long setae are borne on the inner margin of each, two on the
lower part of the inner blade or endopodite, and one on the adjoining end of the stalk or
protopodite (fig. 3 and 4, a, c, d) ; further, that upon these setae a vast number of eggs
find anchorage, and that glands are very abundant beneath the skin of these parts. Four
smaller tufts (e, /, b, g, fig. 3) also carry eggs, and like the former are non-plumose.
Assuming that the cement is derived in part at least from the tegumental glands, and that
the eggs are engulfed in it when they reach the abdominal pouch, it is difficult to under-
stand how in the lobster the true swimming hairs catch so few eggs and in the prawn
Alpheus none at all, unless it be due to gravity or the ability of the animal to direct the
course of the egg stream while lying on her back and gradually changing her position.
The difficulty of explaining this simple fact is not lessened by assuming that the cement
originates in the oviducts.

ORIGIN OF THE EGG GLUE AND FIXATION OF THE EGGS.

Upon reaching the sea water in the abdominal pouch the eggs are fertilized by the
sperm with which the seminal receptacle is charged, and, as seems probable, all are
mixed in a secretion coming from the tegumental glands as well as from the oviducts
by the beating movements of the swimmerets; the cement gradually becomes viscous,
hardens, and eventually incloses each egg in a thin capsule; the individual eggs of the
entire mass are eventually fastened to one another and to certain hairs of the abdominal
appendages by the spun sheets and threads of the glue. The latter is an ectodermic
product and resembles chitin in its appearance and behavior. A knowledge of its
chemical and physical properties when combined with sea water, at the time of its
secretion, would probably include the answer to a number of puzzling questions.

There are three subjects, apart from the more special problems of cytology, con-
cerning the pairing of the higher Crustacea about which exact knowledge is particularly
needed. These are: (1) The exact role played by the cement-producing organ; (2) the
kind of stimulus or stimuli needed to arouse the sleeping sperm in its receptacle, set
it in motion, and direct its course to the eggs; and (3) more light on the action of the
rays, and the “explosive capsule,” by means of which recent students have endeavored
to explain the forced entrance of the head of the sperm into the egg. Direct observa-
tions are too limited at present to afford a basis for the final settlement of any of these
matters.

The origin of the cement has been attributed, on the one hand, to the sexual
organs and especially to the epithelial lining of the oviducts, and on the other to the
tegumental glands of the swimmerets and lower side of the abdomen and to the
egg itself.

NATURAL, HISTORY OF AMERICAN EOBSTER.

307

The older writers, among whom were Cavolini (1787), Rathke (1840), and Erdl
(1843), generally favored the first hypothesis. Lereboullet (i860) was the first to
attribute the cement to the abdomen, and Braun (1875) the first to describe “cement
glands” in the crayfish. Tegumental glands are found in practically every part of the
body covered by the skin or invested by its folds, occurring even in the alimentary tract,
the gills, seminal receptacle, and the “ear sacs.” Feeding experiments with carmine
seem to have shown that they have an excretory function in some degree at least, but
it is equally certain that in some parts of the body they give rise to definite secretions.
At the time of oviposition the pleopods of the female are swollen with what appears as
an opaque whitish substance, which is seen upon microscopic examination to be com-
posed of thousands of these organs. Each gland is hardly an eighth of a millimeter
in diameter, and each opens to the exterior by a capillary duct, the entire length of
which, not including the part which traverses the cuticle, is scarcely more than milli-
meter and its diameter only T|-g millimeter. Such organs are absent or found but
sparingly in the pleopods of the male. After ovulation these glands appear to be for
the most part in an exhausted condition, zymogen-like granules filling the central ends
of their clustered cells. In one case examined, in which the animal had recently hatched
eggs and was about to molt, the glands were shrunken and transparent.

While these facts may be entirely misleading, an observation of Prentiss ( 217 ) seems
to show that this is not the case, inasmuch as glands of this type occur in the sensory
cushion of the otocyst of the crayfish and probably in that of all crustaceans in which
sand particles are adherent to the sensory hairs. Until some more probable source of
the secretion is discovered, it is reasonable to infer with Prentiss that these glands
furnish the glue by which the otoliths are fastened to the pinnules of the sensory setae.

THE OVIDUCT AND ITS PERIODIC CHANCES.

The evidence regarding the part played by the epithelium of the oviducts will not
be perfectly satisfactory until much more is known concerning the nature of the secre-
tions of these organs during the period of egg laying. Our studies of the histological
changes which the oviduct undergoes are limited to two significant stages, one in which
the ovary was nearly ripe and the other from a female with external attached eggs in
yolk segmentation.

It is evident from a comparison of the critical stages that cyclical changes occur
in the oviduct, no less marked in character than those which arise in the ovary itself,
and to which they are evidently related.

By the time the eggs are ready to be laid the oviducal epithelium is distinctly glandu-
lar in type (fig. 3 and 4, pi. xlvii). Its cells become greatly elongated and distended,
while after egg laying they are shrunken to less than one-fourth their former size. When
treated with the common hardening and staining reagents before egg laying, the cyto-
plasm is clear; the nuclei are also clear, elongated by the pressure exerted in the direction
of the short axes of the cells, and lie well down toward the basement membrane. After
ovulation the cytoplasm of the shrunken cells is more vesiculated; the nuclei are more

3°8

bulletin of the bureau of fisheries.

granular, more deeply stained, oval in form, and are farther removed from the basement
membrane. Furthermore, large vesicular cavities occur within or between the cells
next the lumen of the glands, where products of nuclear degeneration are not wanting.

It thus seems evident that the glandular epithelium of the oviducts pour an abundant
secretion over the eggs when these are delivered into the abdominal pouch. According
to the account of Scott quoted above, the eggs are viscous when they leave the ducts,
become adherent in sea water, but soon lose this property. So far as I have been able
to ascertain, eggs to all appearance ripe, which were taken directly from the ducts shortly
after egg laying, were nonadherent and showed no trace of cement or a secondary egg
membrane, but at this time the action of the glands had ceased.

In the lobster with external eggs in segmentation, referred to above, the oviducts
were beaded with ripe eggs, or as Duvernoy expressed it, stuffed like sausages, with eggs
which failed of passage arranged in line, but they were not viscous at the time of exami-
nation, and were surrounded by the chorion only. Assuming that the oviduct contributes
to the formation of the cement, some other chemical products would seem to be needed
to render this effective. These are possibly supplied by the secretions of the tegumental
or “cement” glands of the swimmerets in the presence of sea water. At all events it
would seem that there is poured into the pouch at the time the eggs pass into it an abun-
dant milky or turbid secretion from these glands, which under the microscope is seen to
be swarming with minute floating particles or spherules. A similar secretion occurs in
the crayfish, which after the setting of the cement is found to cover her eggs in a sort
of protective “apron,” as Andrews calls it, a sheet of grayish mucus or glair. When
this is removed the eggs appear bright andfresh beneath it. This “apron” seems to be
a residue of unused material, the presence of which may be needed not only to hold the
eggs and sperm in the pouch but to take part in the production of the liquid hydraulic
cement.

COMPARISONS WITH THE OTHER CRUSTACEA, AND THEORIES OF FIXATION.

In the lobster the glue forms a thin transparent sac about each egg (fig. 5, pi. xliv
mb2), and the capsules of adjoining ova are united by short solid ribbons, or flattened
strands of the same material. Similar bands adherent to the hairs and often coiled
spirally about them hold the entire egg mass to the body. The cement is thus a con-
tinuous sponge work, which is imitated in the manufacture of certain kinds of nut candy,
where the kernels are stirred in the thick sirup and held immersed when it hardens.

Coutierea describes a slightly different mode of fixation in the Alpheidae ( Alpheus
and Synalpheus) , where the eggs or egg-groups adhere only to the stalk of the pleopods,
and never to the fifth pair of swimmerets, nor to the abdomen directly. The supporting
hairs are bunched at the two extremities of the basal stalk and are nonplumose, as in
the lobster.

Where the eggs are few in number, as in Synalpheus longicarpus , they are glued
direct to the hairs, but where more numerous several hairs are cemented into a cable

aCouti&re, H.: Les “Alpheidae,” Morphologie externe et interne; Formes larvaires; Bionomie. Annales des Sciences
naturelles, 8C s6r., Zoologie, t. lx, p. i— iv, p. 428.

NATURAL HISTORY OF AMERICAN LOBSTER.

309

by a flattened membrane with double walls, representing the expanded capsule which
surrounds the egg. In most cases the hairs furnish support to but a small part of the
egg mass, the individual eggs being freely united with their neighbors. Thus in the
prawn Eucyphotes, according to Coutiere, the capsular cement gives off three or four
flattened bands, each of which is soldered at its apex to similar strands from other
eggs. The point of union is marked in each band by a lozenge-shaped or circular thick-
ening. This would indicate that the eggs are surrounded by a layer of the viscous
cement, and separated by seawater until they come together. Each lozenge-shaped
thickening would then represent the original points of contact of egg with egg, the
strands being spun from the sheath by a mutual pulling strain, due to the weight of the
moving eggs.

This condition is especially interesting since it seems to prove that such eggs must
have received their coat of cement before leaving the body. Unless it should appear,
however, that the marks of contact may be completely effaced by fusion of the united
strands, it offers no basis for a general conclusion regarding the origin of the cement
substance in other decapod Crustacea, like the lobster and crayfish. It is probable that
in this as in many other particulars there is no absolute uniformity.

A much more anomalous method of fixation of the egg to the swimmeret is described
by Williamson ( 281 ) for the crab, Cancer pagurus, and in Brachyura generally. Accord-
ing to this observer, the eggs lie thick upon the hairs of the inner branches of the swim-
merets, and are attached by independent and often intertwined stalks, but there is no
union of egg to egg, as in Synalpheus, Homarus, and other Macrura. The eggs are
attached to single hairs, which garnish the endopodites, and usually to hairs only.
There are said to be two membranes in either ovarian or attached egg, namely, a delicate
vitelline membrane and a chitinous chorion. Between these a slight perivitelline space
is formed upon contact with sea water. How does it happen that the eggs escape the
hairs of the exopodite, and how are they suspended to the silken hairs of the endopodite
without a single case of adhesion of egg to egg, and with little sticking of hair to hair?

Williamson in brief offers tlris explanation: “The intimate relationship between
the egg and the hair is due to the hair acting as a skewer, upon which the eggs are impaled
and strung.” Further, the hairs are supposed to penetrate the chorion and pass through
a perivitelline space without injury to the vitelline membrane. The chorion thus pierced
collapses, and a little albuminous perivitelline fluid is pressed out, which becomes adhe-
sive in sea water and serves to glue the chorion to the vitelline membrane and the egg
to the hair; later the glue and chorion is pulled out into the sheets or cords by which
the egg is anchored to the hair.

The solution of the problem of fixation in the eggs of the blue crab appears to
carry us into deeper water than before. In order to make comparisons I have
examined the eggs and abdominal appendages of the blue crab, Callmectes
hastatus. Callinectes lays upward of 4,500,000 eggs,® and the endopodites of the
swimmerets are buried out of sight by the mass. As in Carcinus these myriads of

a Smith, S. I.: Report on the decapod Crustacea of the Albatross dredgings. Report of the Commissioner of Fish and Fish-
eries for 1885, p. 618-619. Washington, 1886.

3xo

BULLETIN OF THE BUREAU OP FISHERIES.

eggs are attached exclusively to the long silken tufted hairs of the inner branches of
the second, third, fourth, and fifth pleopods. They are distributed, therefore, in 8
bunches, with over half a million eggs to a bunch. The appendages are flattened, and
excepting the anterior face near the tip and a portion of the posterior face near its base,
the endopodite is studded with remarkably long silken setae. Each hair carries from
150 to 200 eggs, and each egg is glued by an independent stalk to the hair. Each egg
is, moreover, extremely minute, measuring about xis of an inch (rr<r mm.) in diam-
eter, or smaller than the dot of the letter i of this type. The hairs are extremely
slender, varying in diameter from jfg- of an inch at base to Tjjo of an inch at middle,
beside which a human hair is very coarse and a silken thread a veritable cable. These
attenuated hairs taper gradually to a sharp point.

The exopodite of the swimmeret is fringed with a dense row of plumose setae, which
are not more than one-fifth as long as the egg-bearing hairs of the inner branch and
which, according to Williamson, serve in Cancer as a barrier to prevent the escape of
the ova from the brood-chamber before they become attached. Strange to say, they
do not catch a single egg.

Upon the theory of Williamson, and the assumption of an average cargo of
4,500,000 eggs, we can appreciate the nice work in fencing which would have to be per-
formed by the silken hairs of Callinectes and indirectly by the appendages of the crab.
Some 22,496 hairs would be required to spear and string 200 eggs each, and the feat
would have to be done in the dark, as it were, and upon an egg so small as to be hardly
visible upon the point of a fine cambric needle. But this is not all; the thrusts of the
hairs must pierce a perivitelline space, that is, penetrate a tough chitinous membrane
and be deflected from a semiliquid envelope. If this really happens, it is certainly a
most wonderful performance.

Our objection to such a theory of attachment is based upon general principles,
and before accepting it we should wish to have answers to the following questions.
How is it possible for these delicate hairs to spear anything, and least of all solid spheres
like an egg, suspended in water, and therefore in unstable equilibrium ? The hairs
have no more rigidity than a silken thread; they can hardly stand alone; and when
loaded with eggs at their tips the spearing of additional eggs would seem to be impos-
sible. (2) How is it possible for a spear or needle to penetrate the tough outer coat and
avoid piercing the egg, for the suppositional inner membrane really does not exist at
the time the egg is laid ? (3) Are the almost microscopic eggs pushed along like beads

on a string or birds on a spit, 200 or more crowded in line, and each leaving a viscous
trail, without clogging the line, sticking together, or crowding one another off ? (4) How

is it possible for drops of an albuminous liquid to ooze from a hole in an egg without
spreading over that egg, for a hair in contact with the egg would certainly not conduct
this liquid against the force of gravity, and myriads of eggs must occupy every position
with respect to the hair? Perhaps we can get a better idea of the physical difficulties
involved by imagining a fly-fishing rod reduced to great tenuity and used as a spear
for apples. How many apples of whatever size could its tip hold?

NATURAL HISTORY OF AMERICAN LOBSTER.

311

Before the question of egg attachment in the crab can be settled we must have very
full and exact observations of the behavior of these animals during the period of egg
laying. Now in Callinectes the endopodites are packed full of “ cement ” or tegumental
glands; the exopodites contain fewer glands but an excess of cell disks or concretions
(see 149, p. 108). In fact, Braun called attention to the presence of glands in these
Brachyura over thirty years ago.

If the secretion of the receptaculum seminis of the crabs is limited only to the uses
of the sperm, as seems probable, we are inclined for the present to accept the older
theory, namely, that eggs are glued to the hairs by a cement which is secreted by glands
which lie at their base.

Why the eggs of the Callinectes are not stuck together or why neighboring hairs do
not more frequently adhere is not apparent, and can not be explained until we know
more about the physical properties of the glue itself. The hairs of Callinectes are
covered with a continuous sheet of glue, but are not often adherent. Possibly the eggs
stick to them before they have a chance to become entangled. Each egg is tethered by
a thin spun sheet of glue, which is continuous with a narrowband or sheet, in which the
entire hair is embraced up to the tip or very close to it.

As was pointed out by the writer in 1892 and as had already been demonstrated by
Mayer in 1877, the crustacean egg does not possess a yolk-membrane. The ovarian
ovum and the mature egg when it issues from the ovary, in crustaceans as well as in
insects, is provided with a single membrane, the chorion, which is secreted by the “ovi-
sac” or egg follicle. The great mass of the egg is made up of inert yolk; the protoplasm,
which alone has formative power, is practically restricted to the center of the egg. When
in the course of segmentation or later the protoplasm has reached the surface, a delicate
membrane is secreted by the blastoderm. This often glues the egg fast to the chorion
and gives much trouble to the embryologist. No doubt it was this membrane which
ga/e rise to the mythical “ Dotterhaut, ” or vitelline membrane of Erdl, Rathke, and the
older school of embryologists.

A single membrane only, the chorion, is apparent in the eggs of Callinectes, but since
the cord of attachment spreads out over its surface without any apparent break, the egg
is probably covered with a thin layer of cement which has the same index of refraction
as the chorion to which it is inseparably glued.

Williamson endeavors to extend his ingenious theory of fixation by “spearing” and
the liberation of the cement from the egg itself to the lobster and other Macrura. Thus
he says that the secretion “is not a true cement” capable of forming an outer envelope,
but an albuminous substance, and that “the weight of the egg tends to stretch out the
ductile chorion into long thin stalks.” It is quite certain that the egg of the lobster, as
in all the higher Crustacea, possesses a single membrane when it leaves the ovary, but
the egg attached to the body has acquired a second and distinct membrane which is
continuous with the stalk of attachment. The two are easily separable in picro-sulphuric
acid; the second or outer layer is the “cement membrane” (fig. 5, pi. xliv).

As we have already seen (p. 305) the eggs of the lobster are attached to the non-
plumose hairs of the swimmerets as well as to the abdomen and to each other. Here at

312

BULLETIN OF THE BLTREAU OF FISHERIES.

least it is impossible to apply any theory of fixation which does not involve a fluid
cement substance, engulfing both hairs and eggs, capable of setting under sea water
and possibly in chemical relation to it into a firm “hydraulic” cement which is non-
ductile under ordinary pressures when it is once set.

I have spoken of the chorion as a tough membrane. That this is true is proved by
the vicissitudes through which it passes unharmed. In egg laying the egg is compressed,
being rod shaped in some forms when it passes the duct; it is therefore elastic, but it is
only slightly ductile and then only when under great pressure. The freshly laid lobster
eggs are spherical and as we have seen measure ^ inch (1.5-1.7 mm.) in diameter;
the egg embryo when ready to hatch is oblong, and measures about ^ inch (2.1 mm.)
on the average of the short and long diameters (fig. 33). This swelling in size, due to
embryonic growth, stretches the chorion to great tenuity, until the limit of elasticity
and ductility is reached, and the membrane bursts under the pressure, aided to some
extent by the exertions of the larva.

THE MALE SEXUAL ORGANS.

The paired testes of the male are either distinct or united by a transverse bridge,
and each give off a coiled duct or vas deferens, which opens by a valvular orifice on the
inner side of the first segment of the last thoracic leg (fig. 2, pi. xliv). The duct con-
sists of a proximal division which conducts the sperm from the testes, an enlarged glandu-
lar part, and a terminal muscular or ejaculatory segment. A linear milk-white mass
marks the course of the sperm through the transparent tube. In the coiled glandular
division it is embedded in gelatinous envelopes or spermatophore-sacs ( sph .) secreted by
the lining epithelium. A sphincter muscle (sp. mu) produces an abrupt swelling at the
beginning of the ductus ejaculatorius, the function of which is to eject the sperma-
tophores. The latter have the appearance of semitransparent rods of vermicelli about
an inch long, and consist only of opaque masses of sperm and the gelatinous medium
described. When pressed out artificially, they imbibe water and swell perceptibly.

SPERM CELLS, THEIR ORIGIN AND STRUCTURE.

The sperm cells of the lobster (fig. 31) were apparently seen for the first time by
Valentin in September, 1837, and he gave a brief account of his discovery in the following
year. A more accurate account by Kolliker, who also remarked on the apparent immo-
bility of the “rayed cells,” appeared in 1843, with figures, and notice of the “seminal
sacs” or spermatophores.

The structure and genesis of the spermatozoa of the lobster have been studied with
much detail by Grobben, Gilson, Hermann, Sabatier, and more recently by Brandes {33),
Labbe (275) and Koltzoff (272). Probably few structures in the animal kingdom have
been more puzzling than the rayed cells of the decapod Crustacea. The puzzle consisted
in harmonizing the following conditions as generally found in these animals. The large
eggs of crustaceaus are surrounded by a tough chitinous membrane in which neither pore
nor micropyle has been discovered. The sperm cells may be rounded or columnar, but

NATURAL HISTORY OF AMERICAN LOBSTER.

313

whether devoid of processes of every kind, or provided only with three stiff rays as in the
lobster, under ordinary conditions of observation these cells are absolutely immobile.
Still every thoughtful observer who has pronounced the decapod sperm to be immovable
must eventually recant, and like Galileo declare, “ E pur si muove.” How then could such
sedentary bodies seek, find, bore through the tough shell and fertilize the egg? Brandes,
Labbe, and Koltzoff have offered or worked out fertile suggestions, which afford a satis-
factory solution to the general problem, subject to a course of verification and extension
in different species of crustaceans.

That the “immobile” sperm cells really did move, has been maintained for thirty
years or more by Owsjannikow, Hermann, and Cano. Thus apropos to this subject
Grobben (122) remarks: “The stiffness of the rays does not prove that these cells are
completely immobile. Moreover, the observation of Owsjannikow that the rays some-
times draw themselves in, and certain structures which I have examined, enables me to
conclude definitely that these rays are living protoplasm and that they represent amoe-
boid processes, remaining almost in a state of rest.” (Compare the observation of Cano
quoted below.)

In 1890 Hermann ( 138 ) had described movements of the processes of sperm cells,
and in 1893 that excellent observer, Cano (46), spoke of seeing “certain of the sperm
cells, especially the rayed ones, in amoeboid movements in the sperm receptacle of the
crab Maia.”

In 1896 a remarkable statement regarding independent movement in the sperm
cells of the lobster was made by Bumpus ( 42 ), to the effect that he had “seen the sper-
matozoa in active movement, swimming across the field of the microscope with the
same nervous contractions that are characteristic of the Hydromedusae.”

In 1897 Brandes (33) asked how it was possible for the decapod sperm to enter an
egg where no micropyle could be found, and especially in sperm cells like those of Astacus,
which have no pointed head, but which are spherical and of considerable size. “I
suppose that the sperms at the moment of contact with an unfertilized egg undergo a
change, which consists in this, that a more or less pointed part of the anterior end of
the sperm, the so-called clapper, the “tigelle” of French writers, is evaginated and so
the membrane of the egg which at the moment of egg laying is perhaps somewhat
yielding, is perforated.” This ingenious suggestion, which was elaborated at greater
length, has proved very fruitful, for it was confirmed by Labbe in 1903, and especially
by Koltzoff (172) in 1906, who has worked out the development and structure of the
sperm cell in a number of Brachyura, such as Portunus, Maia, Pagurus, and Eupagurus,
and of Macrura in Homarus, Galathea, and Scyllarus.

According to these later observers, the sperm cell is a very complicated and delicate
machine, beside which a clock or watch seems like a crude affair, especially when we
consider the vast difference in size. This cell may be compared to a self-propelling
torpedo, designed to move in a certain direction, and to explode the moment the cap
or head strikes the hull of a vessel, or any opposing object.

BULLETIN OF THE BUREAU OF FISHERIES.

In the following description of the genesis and structure of the sperm cell of the
lobster, I shall follow in the main the account of Koltzoff (172), from which I have con-
structed a number of diagrams (fig. 31 , i-j, and fig. 32). This account, whether correct in
all particulars or not, is at least intelligible, and we are able to understand the remarkable
evolution in form which these cells undergo in consequence of changes in osmotic pressure.
It is very different from that of Sabatier, who devotes 37 pages to the sperm cells of the
lobster, yet leaves it difficult to understand his descriptions and impossible to construct
any consistent diagrams from his figures.

Fig. 31. — Diagrams of sperm cells of the lobster before (i), during (2), and after (3) capsular explosion, based upon Koltzoff (see
172). a a, plane of section in figure 36; a. ch., anterior chamber; deb, distal central body; Ex. sub., external layer; in. t.,
inner tube; med. t., medium tube; n. proc, neck process or ray; p c b., proximal central body; p. ch.t posterior chamber;
p. mb., outer protoplasmic (?) membrane.

According to Koltzoff the sperm cell is derived by metamorphosis from a spermatid
which in turn arises by division from a spermatocyte of the testis. The centrosome
divides into two parts, and for some time remains united by fibers to the nucleus. The
cell body is stuffed with granules which exhibit a difference in staining power, and in
fact become differentiated into two important parts of the sperm, the mitochondral
body and the capsule.

In the course of these changes the mitochondral becomes pressed against the
nucleus, and molded upon it. A vesicular sperm cell is thus formed, peculiar to the

NATURAL HISTORY OF AMERICAN LOBSTER.

315

decapod crustacean but comparable to the flagellate spermatozoa of other animals.
The crustacean sperm becomes differentiated in three parts, namely, (1) the nucleus or
head, (2) mitochondral body (a partly fibrous and partly granular structure) repre-
senting the neck or middle piece, and (3) the explosive capsule or modified tail.

The sperm cell develops processes (fig. 31,1) which in the lobster arise from the neck.
They ordinarily appear to be immobile and are distinctive of the decapod sperm. The
number of these processes varies from 1 to 10, but 3 is a common number, which is
found in Homarus, Palinurus, and Galathea, as well as in some of the crabs. The
number is of physiological importance, since they are used for orienting the sperm upon
the egg in fertilization. In the true crabs the processes arise from the head and are
therefore nuclear in origin. It may be added that in the prawns (Candida) the usual
processes are lacking, but the capsule ends in a sharp thread-like tail. In the crayfish
(. Astacus ) and many crabs, as well as in Gebia and Callianassa, the neck and capsule
are reduced in size and pressed against the head.

The processes are supported by a central mitochondral, skeletal fiber, or bundle of
fibers. If in the course of development of the spermatid,
these strong skeletal fibers project from the cell body with
free ends, appearing to draw after them the more fluid
constituents of the cell. The skeletal fibers can be demon-
strated by plasmolyzing the cell or surrounding it with a
solution of higher osmotic pressure. These skeletal fibers
are really bundles of fibrils, which have a tendency to spiral
winding.

The capsule (fig. 31, 1 and 2) is a double walled cylin-
drical body, a median tube running through it from end
to end. This tube is formed by a median invagination ex-
tending from the hinder end forward to the neck, and is
expanded at either extremity into a widechamber. The
distal opening is closed by a plug of chitin. A peculiar rod
or “Polster” of stainable substance is pressed from the central body into the anterior
chamber. In the ripe sperm the outer capsular wall and the axial tube consist of
chitin, and may be regarded as continuous, except at the point pierced by the “ Polster.”
This stainable rod is often constricted into a proximal central body in the neck and a
distal central body in the capsule (p and deb).

FERTILIZATION.

In the lobster the sperm cells pass a long latent or resting period in the sperm
receptacle, and may retain their vitality for from one to two years, and possibly longer.
When the eggs are laid, the sperms leave their receptacle, find the eggs, and fertilize them.
The spermatazoa are either pressed out by mechanical force, or else they must be
aroused to activity by a definite stimulus, probably of a chemical nature.

Fig. 32. — Diagrammatic section of
sperm cell in capsular explosion, as
seen in plane a a, figure 31 (3); fd.
in . t. , folded inner tube.

3i6

bulletin of the bureau of fisheries.

By pressing the lips of the spermatic receptacle of a female with internal eggs
nearly ripe, I have observed the sperm in a thick grayish mass which gave up its cells
freely to sea water. This at all events suggests the possibility that the lobster herself
is the direct agent in emptying her receptacle. In any case it is highly probable that
the sperms are directed by chemotropism to the eggs after reaching the water. Nothing
is known by direct observation of the phenomena of fertilization up to this point.

What are the locomotor organs by which the sperms leave the sperm receptacle or
by which they seek and find the eggs in the brood chamber? In our search for an
answer to this question we must remember that the lobster lies upon her back when the
eggs are laid, so that the force of gravity is a bar rather than a help to the movements
of the sperm at this critical period. We may assume first that in leaving the receptacle
the locomotor organs of the sperm cells are the rays or processes, which I showed in 1895
to be rigid in the testes but limp in the receptaculum. This movement is probably
amoeboid in character, consisting in the lengthening and shortening of the protoplasmic
element of the process which flows from the neck of the cell. As with the amoeba a
solid support is necessary for the process of locomotion to be effective, for according
to a recent observer this animal probably draws itself along by the adhesion of its
pseudopodia to the surface over which it creeps.

How does the cell make its way through the water to the egg? No satisfactory
answer can now be given, but if Bumpus was not entirely mistaken in his report of
movements of the lobster’s sperm, as quoted above, we might plausibly suggest the fol-
lowing solution, which is of course purely hypothetical. Upon reaching the water the
plug of the capsule is loosened and falls out. Water then enters and fills the inner tube.
This water is subsequently ejected by contraction of the vesicle, and the cell is drawn
forward by inertia. It should be added here that in some forms ( Eupagurus ) the cap-
sule is covered by a thin protoplasmic layer, and that in this membrane contractile fibers
are sometimes seen; transverse rings can be demonstrated in the lobster. The action
is supposedly recurrent. The processes direct the cell, as do barbs the arrow. The
eggs are big targets, and the moment one is struck orientation of the sperm upon its
surface begins.

At this point speculation gives way in a measure to direct observation, and I return
to the account of Koltzoff ( 172 ) who, like other observers, was unable to see the minute
sperm enter the huge opaque egg. Disclaiming the ability to give a complete account
of the movements of the sperm cells, he says: “My observations and experiments can
naturally clear up only certain phases of these processes, and a whole string of hypo-
thetical conclusions is needed to unite them into a harmonious whole.”

Contact with a large and possibly moving body, or thigmotaxis, seemed to furnish
the most powerful stimulus to the cell processes, which have been observed to shorten
and lengthen, though not to the extent of more than one-tenth of their length. Once
in touch with the egg the sperms begin to orient themselves in such a way that the cell
comes to stand upon its thin elastic processes as upon a tripod, so that the head is placed
in direct contact with the surface of the egg. The elastic process or processes in con-

NATURAL HISTORY OF AMERICAN LOBSTER.

31?

tact with the egg possess an adhesive power; they seem to shorten, and thus to pull the
sperm cell into position.®

In this critical situation when the conditions for fertilization are favorable some-
thing pulls the trigger and fires the gun. That is to say the capsule explodes and shoots
backward, while the head in consequence of the rebound leaps forward and is driven
through the chorion and into the egg.

The space between the inner and the outer capsule is filled with a peculiar explosive
substance, which according to the ideas of Koltzoff possesses the property of swelling
up when it meets with water. Water must either enter through pores of the inner tube
or be absorbed through the outer wall of the capsule. The extension or swelling of the
explosive material is rapid and is usually attended by an evagination of the inner tube
and discharge of the central body.

The sperm cell is thus deformed by the action, and since the character and degree of
the evagination varies with the physical and chemical conditions present the number
of these apparent artifacts is very great.

In actual conditions or in 4.2 per cent isotonic solutions of calcium chloride in sea
water, it is possible to follow every step of the discharge. Labbe in 1894 described the
discharge of the capsule as the final developmental stage of the sperm. The explosion
of the capsule seems to liberate the elastic energy of a coiled spring represented by
the central body, which may show a spiral form in Pagurus or a series of beads, bands,
or granules.

In abnormal capsular explosion, according to Koltzoff, there is a double spring of
the sperm, first forward and then backward. If the suggestion of the free movements
of sperm given above, and for which I am alone responsible, should prove to be an error,
these abnormal explosive movements might account for the contractile pulsations
described by*Bumpus.

According to Koltzoff the energy of the explosion is contained in the explosive
material. When the chitin plug of the inner tube is driven out, water enters and even-
tually penetrates to the inner capsule and brings on the explosion. My suggestion that
water might enter the inner tube and be driven out by a contraction of the protoplasmic
layer surrounding the capsule, thus causing the cell to move forward, presupposes that
water does not at once penetrate the capsule and reach the explosive substance. If
this really happens the suggestion regarding locomotion would be untenable.

No special stimulus was found which would effect a normal capsular explosion,
and it is possible that the sperms respond to a coordinated series of stimuli. Nothing
is yet definitely known upon this subject.

According to Koltzoff the head and neck containing the proximal central body
are driven into the egg and take part in fertilization, while the capsule, with its
processes, in whole or in part, and the distal central body, are left outside and disappear.

Notwithstanding the difficulties, owing to the great size and opacity of the egg and
the small size of the spermatozoa, Koltzoff observed a single case where a normal sperm

a Koltzoff also offers a different and contradictory explanation of the adhesion of the sperm cell to the egg, namely, that the
egg membrane appears in many cases under the microscope to be finely porous, and that the processes are driven like so many
splinters into these pores.

318

BULLETIN OP THE BUREAU OP FISHERIES.

having oriented itself on the surface of the egg exploded and penetrated the chorion;
this happened in three different species of crabs. The capsule of the normally oriented
sperm exploded while in view, and the nucleus was drawn into the egg, but it was impos-
sible to distinguish anything whatever within the opaque ovum. He inferred, but did
not prove, that this series of events represented a true fertilization process.

Several attempts were made at artificial fertilization of lobster eggs at Woods Hole
in 1891, but like the experiences of Koltzoff in 1906 they were unsuccessful. There are
the difficulties of first obtaining perfectly ripe eggs, and, secondly, of meeting the other
conditions of fertilization in which the secretion of glands from the ovaries, oviducts,
or integument of the swiinmerets may play a part. I made glycerine extracts from
the ovaries and oviducts in the hope of finding a chemical stimulus for the sperm, but
did not succeed, the primary difficulty of getting the organs in the proper state of matur-
ity being at that time insurmountable. It was impossible, also, to get any secretions
from the swimmerets by applying electrical stimulation to the ventral nerve chain,
from which they are innervated.

THE SEMINAL RECEPTACLE, COPULATION, AND IMPREGNATION.

The habits of the lobsters at the time of sexual union, so far as at present known,
have been already described. (See p. 302). We have now to consider how the female is
actually impregnated, that is, how the spermatophores are transferred by the male to
her receptacle. According to the account quoted above the transfer is quickly made
while the female lies on her back, and in the three or four cases observed when her shell
is soft.

While no direct observations on the further course of events are as yet available,
the structure of the spermatophore, the male stylets, and the female receptacle render
plausible at least the following account, which is purely conjectural. Before proceeding
with this, however, it will be necessary to examine the secondary sexual structures with
greater care. The seminal receptacle (fig. 6, pi. xliii) lies on the underside of the female
immediately behind the opening of the oviducts and between the bases of the last two
thoracic legs. (Compare p. 301.) It presents the appearance of a light blue shield with
deep median groove. When examined closely it is found to consist of a pair of wing-
like processes, the enlarged sterna of the seventh thoracic somite, with a middle piece
belonging to the succeeding segment wedged between their posterior extremities. The
lips of the median groove are elastic, and if forcibly depressed are seen to open into
a membranous pouch, in which the spermatozoa are carried. The pouch is laterally
compressed and extends directly upward at right angles to the lo'ng axis of the body and
is supported on the link-work of the internal skeleton. (Tig. 4, pi. xliii, sac.) We
should notice that this sac, far from being a delicate structure, is well adapted to receive
rough treatment with impunity. Within, the middle wedge-shaped piece is continuous
with a pair of calcareous rods which form a solid frame for the posterior and upper
part (or bottom) of the sac, where they are firmly sutured to the endophragmal skele-
ton. Within the pouch this sternal bar is prolonged into a stout keel, where it is

NATURAL HISTORY OF AMERICAN LOBSTER. 319

strengthened with yellowish deposits of chitin of a horny consistency. (Fig. 3, pi.
xliv, bar.)

The stylets or modified appendages of the first abdominal somite in the male (fig.
1, a, pi. xxxix and fig. 5, pi. xliii) have stout stalks and a single terminal blade. The
latter is nibbled at the end, grooved along the median side, and bent in such a manner that
when the stylets are opposed they form a covered way. At their hinder extremity they
leave a wide open angle, but partially closed by the spurs of the second pair of swim-
merets (fig. 2, a, pi. xxxix, sp.) when these appendages are naturally extended forward
On the anterior or upper side of the opposed stylets a deep groove on the stalk of each
leads obliquely into the arched passageway. The tips of the stylets when held in this
position diverge slightly, and when pressed into the seminal receptacle the elastic lips
of the latter catch on the nibs and hold the appendages until they are forcibly with-
drawn. The indurated tip of each stylet is interrupted by a minute oval area of soft
membrane, but this does not appear to be the outlet of any peculiar organs. The
tissues of the stylet itself, like those of the swimmerets, generally abound in tegu-
mental glands and large glycogenic cells. In copulation the animals undoubtedly lie
with ventral surfaces together, but apparently do not remain in this position long.
After seizure of the female, the spermatophores are emitted and possibly with the aid
of other appendages are conducted to the passage formed by the stylets, the tips of
which are inserted nearly vertically into the spermatic receptacle and there held in the
manner indicated. The spermatophores not only swell and soften in water, but possibly
may be disorganized before the sperm are free to enter the receptacle, but this is not
probable.

The crustacean sperm, as we have seen, is like a submarine torpedo, loaded and
primed, capable of piercing the membrane and forcing a passage into the egg the moment
its latent energy is set free.

While much of the preceding account is based solely upon inference derived from
a study of the organs and of the changes which some of them are known to undergo, its
presentation may be worth while, if only to call attention to the wide gaps still remain-
ing in our knowledge of the whole process of fecundation in the higher Crustacea.

Chapter X.— DEVELOPMENT.

ANALYSIS OF THE COURSE OF DEVELOPMENT.

The entire course of development for each individual may be conveniently divided
into embryonic, larval, and adolescent periods, which close, respectively, with hatching,
the emergence into the fourth stage, and the acquisition of the secondary sexual characters
and full adult power, reached in the female, according to Hadley, at the twenty-third
molt. The age of sexual maturity or the entire period from larva to adult is subject to
great fluctuation, owing to individual variations, changes in the environment, and to
other causes. A io-inch female lobster may be from 5 to 6 years old, or even older.
There are really no sudden transitions, but only gradual progressive changes, the nature
of which especially at the fourth stage is often disguised by the abrupt passage of the
molt.

The embryonic life within the egg membranes is the most constant, occupying
approximately ten and one half months on the coast of Massachusetts, during which the
stored yolk supplies the materials and energy for growth. When this period is closed
at hatching, the egg membranes burst, and together with a larval cuticle are cast off,
thus leaving the animal free to enter upon an independent career. A remnant of
unabsorbed yolk always remains, however, in the mid-gut region and serves to tide the
little lobster over a critical interval before it is thrown entirely upon its own resources.

Pairing probably does not continue long after sexual union has been accomplished,
yet when confined in ponds lobsters have been known to hold together for several weeks,
and even to occupy the same shelter. (See p. 302.)

Parental instinct developed in the mother is mainly directed to the safe fosterage
of her eggs. The young disperse as soon as hatched, rising to the surface, where they
swim as free pelagic organisms until their larval life is over. Development proceeds
through a series of metamorphoses or individual changes, externally marked by a corre-
sponding series of molts, in the course of which the old cuticle is periodically shed in its
entirety and as one piece to give place to the new covering already formed. The abrupt
molts thus furnish a ready means of following the development and growth of the crus-
tacean step by step from infancy to old age. The embryo virtually molts several times,
though its cast cuticle seems to be mostly absorbed. The first of these membranes to be
shed and absorbed in the egg is secreted by the blastoderm, and was mistaken for a true
yolk or egg membrane by the older observers. As we have already noticed, the ripe
crustacean egg possesses but a single protective envelope, the chorion or flexible shell,
which at hatching time has been reduced to a layer of great tenuity.

320

Bull. U. S. B. F., 1909.

Plate

m •y|

1 ir w)

* B

wgE~. ^

MS jH

Fig. 2.

4 566

Fig. 3.

Fig. i. Growth stages of lobster eggs and young to illustrate relative sizes attained at Woods Hole,
Massachusetts, a, ovarian ova in June; h, external egg in invagination stage, July; r, egg-embryo,
September 1; d, embryo, March 1. In this and following figures, all represented in full size
from alcoholic materials.

Fig. 2. Growth stages of young lobsters continued, e. Embryo at hatching (July); 1 (first line),
first larva, not free from first molt; 1 (second and third lines), first free larval stage; 2, second
larva; 3, third larva; 4, fourth stage.

Fig. 3. Growth stages of the lobster continued. 4, Fourth stage; f and 6, fifth and sixth stages,
respectively.

NATURAL HISTORT OF AMERICAN LOBSTER.

321

When the lobster is ready to hatch, it is therefore covered from head to foot with a
close-fitting chitinous tunic which must be shed before active life is possible. As
explained earlier, this outer garment sticks to the egg coverings and is kicked off when
these are cast aside.

Before hatching and therefore before the molt which occurs at birth, the terminal
telson is forked, and in this respect recalls the more primitive protozoea larva, which
has been attributed to the lobster without any further warrant than this fact; the first
larva resembles an overgrown zoea, and the fourth corresponds in some degree to the
megalops state of the crab.

Since the first larval stage is preceded by a true molt, failure to pass which is often
fatal in the operations of fish hatcheries, it has seemed best to recognize this fact. The
molts and stages will therefore be named and numbered uniformly; molt 1 introduces
stage no. 1, and not stage 2, according to most writers on these subjects; molt no. 4
precedes stage no. 4, and so on.

The first larva (fig. 34 and pi. xxviii) is about one-third of an inch long, and con-
tinues to swim near the surface for from 3 to 5 weeks, or until the fourth (pi. xxxi) or
fifth molt, when it sinks to the bottom and passes the remainder of its life essentially
like an adult animal. The life of such a crustacean is thus made up of a series of stage
periods, each of which represents the time passed between successive castings of the
shell. The first four periods during which growth is most rapid and change most pro-
found are passed rapidly. After this point, and particularly after the sixth or seventh
stage, except for increase in size, there is comparatively little change from molt to molt.

During the three early stages the larvae lack the power of very precise orientation.
They will move steadily for a time with nicely coordinated movements, when their
equilibrium is suddenly upset and they begin to reel or turn over completely. This
seems to be due to the fact that their statocysts, which are the most important balancing
organs, are not well developed until the fourth stage.

Twins and monsters are occasionally born, a fact noted by Brightwell in 1835, but
this seldom if ever occurs under normal conditions. (See ch. viii, p. 287.) In two cases
of twins observed by Anderton in the European species one larva was released earlier
than the other, which continued to rotate in the egg until set free.

The following changes in structure and instincts take place at the fourth molt 01
beginning of the fourth stage, which marks the most surprising leap in the whole history
of development: Loss of the primitive swimming branches of the thoracic appendages;
the cuticle becomes shell-like, containing more lime; the pigments are denser, the colors
brilliant, and the color pattern variable; otocysts are present and orientation is perfect;
rotation of great forceps is complete; the animal, during at least a part of this stage,
moves toward the light and swims steadily at the surface with great claws directed
forward and held close together; the preying instinct is more marked; the fighting
instinct, the instincts of fear, “feigning,” and hiding are all developed at the beginning
or close of this stage or in the fifth, which follows, when the animal goes to the bottom
to stay.

48299° — Bull. 29 — 11 21

322

BULLETIN OF THE BUREAU OF FISHERIES.

When a bottom life is finally adopted, the instincts of burrowing, hiding, wariness.,
pugnacity, and preying become strongly accentuated. The animal is negatively photo-
tactic and tends, as in all later stages upon the whole, to avoid strong light.

In the larval lobsters the big claws are prehensile organs solely, by which the food
is seized and transferred to the mouth parts. At the fourth stage the great double
claws are perfectly developed, similar in structure, and of the primitive toothed type.
The smaller chelae and other appendages are in perfect symmetry. At about the sixth
or seventh stage a difference in the big claws begins to appear, the claw on one side
developing crushing tubules and becoming larger and heavier in accordance with the
greater development of its muscles. The smaller forceps, the jaws of which have
developed serially arranged teeth, retains its primitive form. Whether right or left
claw shall be of the toothed or crushing type is predetermined in the egg, all members
of the same brood in all likelihood being either right-handed or left-handed. (See p. 274.)
Injury or mutilations, however, may determine the position and character of the claw
in after life.

At the seventh molt the cast shell is blue with some green and brown pigments
on the tergal surfaces. Pigment is thenceforth more and more deposited in the outer
calcified layer of the shell, which becomes wholly responsible for the color of the animal.
The dorsal median stripe of the carapace, -which marks an absorption area of distinct
service in molting, is much narrower than when first observed in the fourth stage. At
the time of the fourth molt this linear area is one-eighteenth of the width of the carapace
at its widest part. It gradually narrows until in the adult state it is in the proportion
of one-sixtieth or less.

The sex can be determined as early as the eighth stage by the openings of the sexual
ducts, which in the male arise in the coxa or basal segment of the last pair of thoracic
legs and in the female on the coxae of the third pairs of pereiopods. The sex can not
be determined by the modified swimmerets of the first abdominal somite until some time
between the eighth and the tenth molt. At about the eighth stage also the peculiar
seminal receptacle of the female begins to undergo its characteristic differentiation.

During the adolescent stages, when the lobster of either sex measures from 1 >2 to 4
inches in length, there are certain marked characteristics — the relatively large size of
the eyes, recalling those of the shrimp Penaus setiferus and probably a relic of an
ancestral stage, the fringe of long setae on the tail-fan, and the tufts of hairs about the
ends and along the serrate jaws of the toothed claw.

With this introductory sketch, we will examine more closely the embryo and larva,
although it is not our intention to enter minutely into all the details of their structure.

EMBRYO.

The freshly laid eggs are dark green, almost black in color owing to the presence
of the soluble pigment, a lipochromogen, in the yolk, and the glass-like transparency of
their membranes. (Compare p. 298.) The golden yellow variation, which is often
associated with dark green, as in the eggs of certain shrimps, has not been observed in

NATURAL HISTORY OF AMERICAN LOBSTER.

323

the lobster, but its eggs are occasionally straw color, grayish-green, or yellow-green.
When plunged in alcohol or hot water the ova respond like the shell of the animal and
become light red, a more stable pigment, a lipochrome, soluble in alcohol, being formed.
By adding alternately hot and cold water the eggs may be turned to red and green
several times in succession.

The fresh-laid eggs, which are seldom seen, can be detected by examination with a
hand lens. The transparent capsule closely invests the yolk, which presents a very
fine-grained and uniform texture, quite different from that which the ova later possess.
Maturation is without doubt completed by the formation of polar cells either in the
ovary or during the passage of the eggs to the outside, although we have never been
able to find these bodies in stained sections of the egg. External segmentation of the
yolk follows in from 20 to 25 hours after oviposition, and the large yolk segments which
are early formed can be detected by the naked eye. A clear perivitelline space,
apparently filled in part with exudatian from the egg, soon appears between the shell
and yolk. At the close of this process, or after invagination has begun, the living egg,
when examined with a hand lens or low power of the microscope, is likely to be mis-
taken for one freshly laid. The ova, however, are not so closely adherent, are somewhat
lighter in color, and the yolk has a coarser and more irregular texture. The first division
of the protoplasm is central or subcentral. In the second and third segmentations,
with four and eight cells, the products begin to separate and migrate outward. The
greater number tend to move toward the side which marks the animal pole, where the
yolk becomes distinctly flattened, and the shell correspondingly elevated. The cells
which migrate toward the surface of the depressed area bring about the first segmenta-
tion of the yolk into hillocks. As they multiply by indirect division their products
diffuse over the egg, and at the fifth segmentation, of 32 cells, the entire surface of
the yolk is thrown into hillocks or inverted pyramids. The segmentation is rythmical,
the early periods lasting about 4 hours, but the rythms of individual cells are not
in harmony, and the segments are unequal. Later when about no cells are present
the periodic divisions become more uniform over the entire egg. With each division
the protoplasm approaches nearer the surface, and meantime a limited number of cells
are formed by tangential divisions and migrate to the depths of the yolk. By a con-
tinuation of this process the yolk becomes surrounded by a thin mosiac of cells, or
rather by a single tier of several thousand minute columnar cells or diminutive yolk
pyramids of uniform size. Their “apices” blend into the central yolk mass, which
harbors a few wandering and degenerating cells.

Cell division then becomes more rapid over a considerable area of the surface,
which includes the animal pole, and at a certain point an invagination of superficial
cells occurs. This begins by the in-wandering of a few cells, and is followed by the
rapid multiplication of those thus immersed in the common food stock of the developing
egg, and by the sinking of a small area of the blastoderm about this point, forming what
is usually called the “egg gastrula” stage. The depression is at first shallow, and
becomes a well-defined circular pit, but is never very deep. It is subject to marked

324

BULLETIN OF THE BUREAU OF FISHERIES.

individual variation, but commonly elongates transversely to the long axis of the future
embryo, endures 4 or 5 days, and then completely disappears. In front of the pit
a wide embryonic area is defined by rapid divisions of the surface cells. The latter,
which are the direct descendants of the enormous yolk pyramids or hillocks, become
distinctly separated into a single stratum of yolk-laden and columnar cells. Below the
point of invagination the ingrowing plug of cells expands by rapid divisions of its
elements, and like columns of smoke from a steam engine a dense cloud-like mass is
spread into the yolk. Many of the cells break loose from the syncytial mass and worm
their way through the yolk like independently moving amoebae. Many of them degen-
erate, while others creep forward and attach themselves to the embryonic area. The
cells introduced by invagination give rise, in terms of the germ-layer theory, to the
hypoblast or endoderm, and to at least a part of the mesoblast. It is almost certain
that the yolk-wandering cells receive many recruits from the surface of the embryonic
area; the yolk cells introduced earlier for the most part degenerate before the stage
of invagination is reached. By multiple divisions cell nests are formed, particularly
in the embryonic region at the surface, or more commonly just beneath it in the midst
of spheroidal masses or balls of yolk.

Death waits close upon the birth of new cells, and from an early stage to the later
egg-nauplius period degeneration is a marked characteristic of this and many other
arthropod embryos. Nebulous clouds of chromatin strew the paths of cell migration,
and are carried to every part of the egg, where they remain until absorbed. In the
early stages at least embryonic layers do not exist, and attempts to reconstruct them
out of a mass of rapidly multiplying, degenerating, and moving elements, by the aid
of theory and the imagination, have thus far proved neither successful nor profitable.

The appendages are the first of the distinctly embryonic parts to make their
appearance; they are formed by paired tubular folds of the body wall. They pos-
sess solid yolk cores which are gradually absorbed and replaced by mesoblastic cells
which migrate from the embryonic region. The limbs arise in pairs in the following
order: (1) First antennae, (2) mandibles, (3) second antennae, (4) first maxillae, and
the remaining thoracic appendages in regular succession. The second antenna soon
becomes bilobed, the inner branch representing the future long “whip” or flagellum
of this limb. The first antennae remain single until shortly before hatching, when
the inner flagellum buds out from the inner lower surface of the primary stalk (see
p. 226). The optic disks, at first paired rounded areas of rapidly dividing cells, soon
become elevated into lobes and form the rudiments of the large eyestalks. The
mouth appears at about the ninth day as a median pit on a line drawn through the
hinder margins of the buds of the first antennae and before the second antennae are
formed. At the tenth day the three pairs of nauplius-appendages are present as
buds; a day or two later the upper lip or labruin has grown down over the mouth and
a larger fold representing the abdomen and a part of the thorax has grown forward
from the region of the thoracic-abdominal plate, marked by the earlier point of invagina-
tion. At 14 days of age the latter fold is divided at its extremity, which represents

NATURAL HISTORY OF AMERICAN LOBSTER

325

the forked telson-plate of the larva and touches or overlaps the lip. In 3 weeks the
conical eyestalks are most prominent; 8 to 9 pairs of appendages are present, and
the telson overlaps the brain. The brownish black eye pigment of the retinal cells
begins to appear in the fourth week as a thin crescent at the base of each lobe, and
gradually extends in area until in 3 or 4 months time it forms the large, rounded eye
spots, so conspicuous a mark from this time onward. A cuticle to be later absorbed
surrounds every part of the embryo, and rudimentary setae are beginning to appear on
the telson plate and antennae.

Up to the fourth week internal changes, which we shall not attempt to describe,
have led to the already complex foundations of the nervous and muscular systems,
the heart, and alimentary tract. Of the latter the stomodaeum or oral invagination
gives rise to a distinct pouch from the epithelial lining of which the cuticular coat of
the mouth opening, esophagus, and stomach sac are derived. The proctodaeum,
feo which the anal opening and lining of most of the intestine is due, is similarly formed
through a median ingrowth of ectoderm near the posterior end of what becomes the
thoracic abdominal fold. The cuticular lining of the intestine when formed, like that
of the stomodaeum, is continuous with the outer skin and must be shed at every sub-
sequent molt. The proctodaeal invagination is at first solid or nearly so and is not
sharply bounded from the yolk, which with its inclosed cells distinguished as hvpoblast,
represents the embryonic section of the digestive tract, called the mesenteron, and
gives rise to the gastric glands and to the epithelial wall of a small section of the tract
into which they open. The walls of the mesenteron become continuous with those
of the proctodaeum and are gradually extended forward on all sides until the entire
yolk mass of the egg is inclosed within the folds of the paired gastric glands and forward
division of the intestine. At a later period of embryonic life the screen which separates
the stomodaeum from the yolk is absorbed and its walls unite with those of the mesenteron.
At the time of hatching the residue of the yolk lies in the folded walls of the lobulated
gastric glands, from which it is finally absorbed. This residual yolk sometimes appears
to pass to the masticatory stomach, but if this ever happens it must be due to secondary
displacement, as will be readily understood from the relation of the yolk to the mesenteron
just described. The functions of digestion and absorption, which the gastric glands
or liver display on a large scale throughout the embryonic period, are retained in adult
life as already noticed. (See p. 249.)

The intestine in the higher Crustacea, excepting only its terminal portion, is com-
monly described as arising from the endodermal or hypoblastic wall of the midgut,
or mesenteron, but this is certainly not the case in the lobster, which sheds an intestinal
cuticle during its pelagic stages. A median longitudinal section through the body
of the larva at the time of hatching shows a distinct cuticle passing forward along
nearly the entire length of the intestinal tube, and finally shading off and disappearing
opposite the gastric glands. The epithelial lining of the intestine is therefore almost
wholly of ectodermic origin and continuous with the epithelium of the skin, a conclusion
which embryological study fully supports. Apparently in the adult animal the cuticular

326

bulletin of the bureau of fisheries.

lining terminates abruptly at the forward end of the rectum, but this is not the case
in early life.

During the course of development the ova increase considerably in size, and, losing
their original globular form, become distinctly oblong (fig. 33, a and b). The bright red
pigment cells or chromatophores, which are distributed in a characteristic manner,
particularly on their basal segments and on the sides of the carapace, are prominent
for a long time before hatching. These, together with the interference colors of the
huge eye-spots and the rich green of the unabsorbed yolk, give the eggs of the lobster
exceptionally brilliant color patterns.

EXCLUSION AND DISPERSAL OF THE BROOD.

Fig. 33. — Outlines to show relative sizes
of lobsters' eggs when laid (a), and when
ready to hatch (6). Enlarged about
$lA diameters.

It was found that when the eggs at the point of hatching were removed from the
mother lobster and placed in jars at Woods Hole a full week elapsed before the entire
brood was set free. Possibly the period is shorter when the animal is undisturbed
and left to her own devices in the sea. When other conditions are favorable, the warmer
the water the more rapid will the emissions occur. The individual variation in the
eggs entailed by the long period of fosterage render it certain that all can not hatch

simultaneously. Fullarton {113) found that in the Euro-
pean lobster the time required for the hatching of a
brood varied from one to three weeks or even longer,
but it is not likely that this period is extended to very
great lengths under natural conditions.

The egg-bearing lobster instinctively folds its tail,
thus securely inclosing the eggs in the abdominal pocket
when in danger of enemies, while at other times she is seen at intervals to extend her tail
and, standing upon her legs and incurved tail fan, move her swimmerets back and forth.
In this way the eggs are aerated and cleaned, and such actions proceed instinctively during
the 10 months of parental care which they receive. The cargo of eggs shows the effects of
the treatment, for they pass the storms and stress of winter with remarkably little loss,
and come to point of hatching bright and clean. It is rare to detect a single barren egg
or broken embryo among the thousands of perfectly formed young. Yet when the egg-
bearing lobster or crayfish are too closely confined, or the normal conditions of their
environment seriously disturbed, sediment soon clogs the eggs and parasitic protozoa
and other organisms attack and destroy the egg glue to such an extent that the ova
fall off of their own weight and soon perish.

It might prove to be a point of some interest to determine whether the rhythm
of the swimmerets is fairly uniform or not from the beginning to the end of the period
of fosterage, but nothing can be said on this subject at present.

The behavior of the American lobster at the time of the emission of the young
has not been studied with sufficient care under natural conditions; accordingly, I tran-
scribe the following observations made on the European species by MM. Eabre-Domergue
and Bietrix ( 101 ).

NATURAL HISTORY OF AMERICAN LOBSTER.

327

In order to ascertain as exactly as possible the age of our young lobsters, we determined to collect
them for the space of twelve hours, a circumstance which led us first to find that hatching never takes
place by day. Atfrom six to seven o ’clock in the evening not a larva was visible in the water of the float.
Two hours later we could see several hundred of them swimming about. If we removed all of the
latter with care, no new arrivals appeared before the evening of the following day. To what was the
rapid emission of larvae in so short a time due? The continual observation of our float during the
first hours of night soon showed us the key to the enigma.

Toward seven to eight o’clock in the evening the female commenced to stir herself in her prison
by presenting an attitude altogether unusual and characteristic. Her feet are stretched out almost
rigid, her tail extended to the full in a horizontal direction, forming, with the rest of her body,
a nearly straight line. She walks, as we might say, upon her toes, so careful is she to hold her entire
body as far away as possible from the bottom of the aquarium. This feat lasts for a certain time; then
quickly lowering her head and the fore part of her body until she rests upon the ground between her out-
spread claws, with tail on the other hand raised at an angle of 45 degrees and kept stretched, we see
her violently shake her swimmerets with such rapidity that the eye cannot follow the movement,
and a veritable cloud of larvae are sent far to the rear and dispersed in all directions.® This phenomenon
lasts from 15 to 20 seconds, and the female thereafter returns to her habitual attitude, to depart there-
from no more until the following evening. We have repeatedly verified the fact by observing always
that the larval emission is produced in certain cases by two series of distinct movements, lasting some
minutes, the second producing much fewer larvae than the first.

The hatching does not therefore proceed independently of the mother and does not take place at
all times of the day and night, but is confined to the hours of eight to nine o’clock in the evening.

The first molt which follows hatching is effected in the hours which precede the emission, and it
is without doubt the movement of the larvae under the abdomen of their mother which causes in her
these signs of agitation and unrest already described. If, in short, one tries to draw the female out
of the water when in this condition, we can see in her movements of defense the downfall of a great
number of larva previously hatched but doubtless united to their mother by the molted membrane which
her violent movements sufficed to break or to detach. Unfortunately we have been unable to assure
ourselves whether, as Laguesse has observed in the crayfish, the young are found attached by the telson
to the debris of the shell or of the molt (compare p. 167).

It should be noted that on occasion larvse appear to be normally hatched in the
daytime, and that a few may even resist the movements of their mother to disperse
them, and remain for some little time attached to her body, though capable of swim-
ming. In regard to the hatching of the European lobster when confined in ponds
at the marine fish hatchery and biological station at Portobello, New Zealand (see p. 298),
Mr. Anderton has written to me as follows: The hatching “almost always takes place
at night. I say almost advisedly, since this last season a batch has frequently been
hatched during the afternoon by a violent aeration of the tank water. I think about
1,700 has been the largest number hatched from a single individual during one night.”

THE HATCHING PROCESS.

As already observed, what we shall consider the first molt of the larva is passed at
the time of hatching, and in this act the larval cuticle and shell membranes are shed
together. The stalked secondary egg membrane, representing the glue or fixative by

o With this specific and graphic account compare the brief statement of Coste, made nearly a half century before, that
“The brood females straighten their tails, which up to now have been carried bent against the plastron, gently oscillating those
appendages to which the bunched embryos are attached, as if to scatter the larvae, and to aid them in breaking the shell, and
hus free themselves in the course of a few days of their entire cargo.” (55, p. 205).

328

BULLETIN OF THE BUREAU OF FISHERIES.

which the eggs are attached to each other and to the body of the mother, in consequence
of internal pressure, splits lengthwise of the embryo and its two halves separate like the
skin of a pea. The primary eggshell or transparent “chorion,” reduced by distention to
a sac of great tenuity, adheres to the outer capsule at a point usually beneath its stalk
and is in turn apparently adherent in some degree to the embryonic cuticle. Further,
the invaginated hairs or setae of the larva about to issue stick by their tips to the cuticular
sheaths of the corresponding setae. Consequently, successful hatching in the lobster
means shedding the egg membranes with the old cuticle and the pulling out of the
invaginated hairs of the new chitinous covering at the same time. Hatching and molt-
ing thus go hand in hand, and the first larval stage, like every period which follows, is
preceded by a molt. The fact that hundreds of the larvae which are hatched by artificial
means get clear of the eggshells, but die through inability to cast this embryonic cuticle,
illustrates the importance of these nicely adjusted relations.

It is thus evident that we can not help the little lobster out of its shell, but must let
it escape in its own way, and if healthy it will cast in a few minutes. Its old covering
must be shed in one piece and with the loss of as little energy as possible. The infant
lobster hatches, molts, and unsheaths its swimming hairs at the same time, as was
explained more fully in an earlier chapter (see ch. vi, p. 236). The eggshell, as we have
also seen, sticks both to mother and child, while the cuticle of the latter is in turn glued
to the swimming hairs of the new skin, so that every tug at the shell helps to free the
little lobster from its hampering cloak and at the same time to perfect its swimming
apparatus.

The young lobster is very compactly folded in the egg, which becomes ovoidal in
consequence of growth. At the time of hatching this marked ovoidal form of the
embryo is largely determined by the form of the carapace, which is longer than broad.
The body is bent, but not twisted, the tail, as in all crustaceans, being folded against
the thorax and head, the tips of the telson plate even reaching beyond the compound
eyes and to a point overlying the masticating stomach. The mouth is thus covered by
the overlap of the hinder part of the fifth somite of the abdomen, which also presses
against the downwardly bent rostrum and the mouth parts. The antennse are directed
backward along the free borders of the carapace, while the thoracic appendages with
their outer branches, like a double bank of oars, are directed downward over the abdo-
men and forward toward the middle line. Hatching thus implies not only release from
the egg membranes, but casting off a complete cuticular molt and at the same time
the evaginating or drawing out of every telescoped hair and spine of the body, including
the rostrum; further, in addition to this and aided by it, the unfolding of the abdomen
and the straightening of the telson and the various appendages.

Little difference in the size of the eggs was noted by Anderton (5) in the European
lobster until the last month of development, when they increased as much as 3 milli-
meters in length in conformity to the shape of the embryo, and when convulsive move-
ments of the embryo itself were often violent enough to move the egg from under the
object glass.

NATURAL, HISTORY OF AMERICAN LOBSTER.

329

THE FIRST LARVA.

[PI- xxviii and text fig. 34.]

When the lobster has successfully escaped from the egg capsule and shaken itself
free from its cuticle, it emerges as a free-swimming animal and eventually rises to the
surface, where it remains rising and sinking, but probably never far removed from the
actual surface until its pelagic life is over.

Fig. 34. — First larva, or first swimming stage of the lobster in profile. For drawing colored to life, see plate xxvra;
for natural swimming hold page sidewise with head of animal down, and compare figure 40 of text. Length
about 8 mm., or a little less than % inch.

The animal is but little over a third of an inch long. The body is segmented as in the
adult form, the most striking characteristics being the enormous eyes, the conspicuous
rostral spine, which projects like a sharp spear in front, the triangular telson, and the
biramous swimming legs, which, from their resemblance to the permanent swimming

330

BULLETIN OF THE BUREAU OF FISHERIES.

organs of the sehizopods, have given to this and the two succeeding larvae the name
of the “schizopod” or “mysis stage.” Functional appendages are wanting only in the
abdominal segments, where, however, very small buds of the adult swimmerets can be
seen beneath the cuticle in the second, third, fourth, and fifth abdominal somites.

The cuticle of the larval lobster is now as translucent as glass, and such organs as
the heart and blood vessels, the alimentary tract, and the rudimentary gills are seen with

Fig. 35. — Cephalothorax of lobster in first stage when under stimulus of pressure, drawn immediately
after reddening, through expansion of chromatophores. a, b, lateral and dorsal red chromatophore
groups; yellow pigment not here shown.

Fig. 36. — Cephalothorax of the same individual 10 minutes after release from pressure, and after paling
from contraction of chromatophores. Both the red (solid) and yellow (dotted) pigment cells are
indicated.

great clearness. The green food yolk has disappeared entirely or is reduced to a mere
remnant now more yellow than green, in the masticatory stomach. Perhaps the most
conspicuous internal organ is the yellowish-brown “liver,” or gastric glands, the form of
which on either side of the body resembles a cluster of grapes.

NATURAL HISTORY OF AMERICAN LOBSTER.

331

Color of the larva. — The gay coloring of the larval lobster, aside from that con-
tributed by the internal organs and contents of the ailmentary tract, is produced by
a blue pigment dissolved in the blood plasma and by red and yellow chromatophores
which lie in the dermal layer of the skin, besides the pigment cells of the eyes. The
distribution and grouping of the red chromatophores is very characteristic, and it is to
these that the brilliant colors of the larvae are largely due. The red cells are the larger
and play the most prominent role. The expansion and contraction of the chromato-
phores, by which the animal becomes brightly colored or pale, ordinarily requires from
xo to 15 minutes when stimulated by pressure and released (fig. 35 and 36). The
chromatophores are distributed in a number of well-defined regions, namely the cara-
pace, in front of the cervical groove, the gill covers or sides of the carapace, the large
claws and bases of the cephalo-thoracic appendages, and the dorsal surface of the abdomi-
nal segments, including the telson. These centers of color distribution are well marked
from a late embryonic period to the lobsterling or fourth stage, when the change in the
lobster’s coloring is no less profound and abrupt than that of its structure and habits.
When the chromatophores contract under the influence of a stimulus the animal becomes
pale blue and very translucent ; when they expand the vermilion cells give it a much
more decided color. Pale blue at night, bright red by day is the rule, and among
external agents sunlight seems to provide the main stimulus which causes the chromato-
phores to expand, but other changes, like raising the temperature or applying pressure
to the body, will produce a like result. If the young lobsters are suddenly placed in
darkness they tend to become paler and if returned to the light to redden more or less
promptly. But the internal conditions or physiological states of the animal evidently
present another and highly variable factor. All larvae do not redden in the sun and all do
not pale in darkness, while some respond more promptly to all such changes than others.

When the larvae are seen struggling on the bottom of an aquarium, to get free from
their old cuticle, when crippled in any way, or as Hadley remarks, when starved for
some time, they so often turn red that this color has been regarded as a sign of weakness.
On the other hand, if thousands of larvae hatched and reared indoors are suddenly set
free in more brilliantly illuminated water outside, a large proportion of them will redden,
though not all. It has been asserted that the young and adult in all stages are upon
the whole more active by night than by day, and that the young tend to move toward
the source of light, or toward the surface where they find their suspended food. If the
latter statement were true, we should expect to find the young larvae at the surface of
the ocean in the daytime and in active movement. Prof. S. I. Smith has taken the
larvae in all stages in the surface waters of Vineyard Sound in the daytime, and in sev-
eral instances when using an electric light at night. These larvae are often seen to pursue
their prey by sight, and it has been shown that they can orient themselves through the
medium of the eye. We thus seem to become entangled in a web of contradictory
statements. The larvae are more active in twilight or at night, but seek the light, and
pursue their prey in the daytime, by the aid of sight. Red is a symptom of weakness,
but they redden in the light.

332

BULLETIN OF THE BUREAU OF FISHERIES.

The difficulty seems to lie in the fact that any given reaction is the resultant of
complex conditions, which can be regularly repeated only when those conditions remain
uniform. The life of the lobster during all of its free swimming life is apparently one
of incessant activity, whether swimming at the surface or at whatever distance below
it, and at all times of the day or night. In the account of their reactions to light, which
later follows, it will be seen that their behavior is very complex and very variable. Cer-
tain responses may not only vary but even disappear altogether in consequence of
changes in the organism or in the stimuli which affect it. Further, since the chromato-
phores as well as the muscles of locomotion are under reflex control of the nervous
system, it is not more surprising to find variations in the responsive behavior of the
pigment cells than in the activities of the body as a whole.

All that can be definitely said at present concerning the gay and plastic coloring
of the larvae is that it is an expression of chemical and physical changes in the body, due
to stimuli, some of which are unfavorable, and that they have no protective significance.
If every larva remained pale while swimming at the surface in the daytime, and took on
color only at night, which is not the case, there would be no reason for supposing that
there was a relation between the origin of the habit and the protection which it afforded
because of the vast indiscriminate destruction which all such larvae suffer at the hands
of inanimate nature. That any such hypothetical protection would really count for
nothing is further shown by the fact that the young lobster emerges at the fourth stage
in a richly colored dress which renders it more conspicuous at the surface where it still
swims than it would be if it remained colorless. For the continuance of the race a single
lobster in the fourth stage is worth many hundreds in the first, and we should hardly
expect to find nature at one moment using certain measures to protect life and at the
next the same means for destroying it.

Both the blue pigment of the blood and the yellow and red pigment of the chromato-
phores, as already remarked, are lipochromogens, which are converted into lipochromes
under a variety of conditions whether the animal is dead or alive. The stomach and
liver are sometimes bright red, which recalls an observation by MacMunn, who con-
cluded from spectroscopic evidence that in the lobster ( Homarus gammarus) the entero-
chlorophyll of the liver might be carried to the hypodermis and converted into a
lipochrome.

Structure and habits. — The most striking habits of the little lobsters immediately
after birth are their incessant and apparently aimless activity, their preying and fighting
instincts, and their voracity, which invariably results in cannibalism whenever the food
supply is insufficient or unsuitable and where the young are too closely crowded in either
vertical or horizontal limits; their seeking or avoidance of light under the variable sum
of all the conditions which influence their behavior; their unstable, vacillating movements
in the daytime or when stimulated by strong light ; the total absence of the instincts of
fear and concealment so clearly expressed at a later stage; their sharp vision for small
floating particles at close range; their lack of precise discrimination, snapping up many
inorganic particles or dead organic substances which are useless as food; their pursuit

NATURAL, HISTORY OF AMERICAN LOBSTER.

333

and often successful capture of copepods and other members of the plankton or floating
population, showing that they can direct their movements with a certain degree of
precision when necessary or when the light and other conditions are favorable.

The body of the little lobster is armed at most vulnerable points with defensive
spines, and its various appendages bristle with tactile hairs or setae, as well as with
more diminutive spines, which may afford some slight degree of protection against
smaller enemies when they do not assist
it in seizing and tearing its prey.

The free margin of the “paddle,”
or forked telson plate, as commonly
seen in the larvae of the higher Crus-
tacea, is garnished with very uniform
and symmetrical spines and plumose
hairs.

It is interesting to observe that cer-
tain spines and the setae whatever their
size or function, from the rostrum or
tips of the claws down to the smallest
microscopic hair, agree in their essen-
tial structure, and are all developed as
tubular folds or outgrowths of the
integument. In the course of the pre-
natal molt all the spines as well as the
hairs are telescoped or invaginated.

(Compare p. 269-270.)

In swimming the young lobsters
use the outer branches or exopodites
of the thoracic limbs (segments ix-xiv,
table 4), by the beating movements of
which they are slowly driven upward,
downward, or forward (compare fig. 40),
and the abdomen, by the sudden fold-
ing of which and by the aid of its broad
telson plate, they dart rapidly back-
ward. Each thoracic leg, in conformity
to the type of decapod limbs, consists
of a short stalk or protopodite and two diverging branches, the outer branch or exopodite
which serves as a flexible “oar,” being flattened and fringed with long feather-like hairs.

The “oars” work independently of the inner branches, which in the larva are
mainly prehensile organs, and which with the stalk alone give rise to the adult limbs.
The concerted vibratory strokes of these minute flexible oars is so rapid and so uniform
in vigorous larvae that at a short distance from the eye it is impossible to follow their
movements.

Fig. 37, 38, and 39. — Parts of setae from cheliped of larval lobster,
showing different degrees of reduction from typical plumose
type. Enlarged 85 times.

334

bulletin of the bureau of fisheries.

The exopodites atrophy, and are reduced to microscopic rudiments in the fourth
stage, and completely disappear in the fifth. No doubt in this respect there is variation,
however, as Williamson ( 282 ) has found to be the case in the European lobster.

In rising with head inclined, the body is usually bent into a quadrant, and according
to Hadley (131) when the appendages are extended forward the exopodites strike
somewhat forward as well as downward and thus drive the lobster upward and backward
(fig. 40, c) ; when on the contrary the thoracic legs ate contracted or drawn backward
the larva is driven forward and upward. Whatever the direction of movement, as this
observer has also pointed out, the animal always heads away from the source of light.
In swimming near the surface the thorax is sometimes held horizontal with tail bent at
an angle of 45°,more or less (a) ; when riding down another larva, feeding upon its carcass,
or grappling with a lobster’s egg the body is straightened (6) ; in the ascending currents
of a hatching jar the young frequently come to the surface tail uppermost, and body
vertical (d). By bending the body theweight is concentrated, which is especially advan-
tageous in swimming upward. As Williamson remarks, the position of the body is
correlated with the beats and direction of motion of the exopodites.

In hovering over the bottom, “standing on their heads,” and as it might appear,
probing the sediment with the rostrum (fig. 40 /), they are not trying to escape the light,
as one observer has suggested, but are oriented for rising, being too weak, however, for
any sustained effort. In every hatching jar or container many weakened individuals
gradually settle into the sediment, a veritable trap for them, at the bottom, at first
kicking away with strokes of the tail or standing erect with every oar in motion, but
finally keeling over on their backs and beginning the death struggle to which there is
usually but one ending.

The mutual destructiveness of the young lobsters when too closely crowded in
aquaria has already been mentioned. When one lobster attacks another under these
conditions the pursuer usually endeavors to get astride of his victim and with its sharp-
pointed prehensile legs nip into the abdomen at its junction with the carapace. When
the prey is an object too heavy to float, the lobster is frequently carried to the bottom;
but if the animal is healthy it will be usually seen swimming about the aquarium drag-
ging its prey with it and feeding upon it as it goes (fig. 40 6).

The beating of the heart and circulation of the blood begins at about the fifth
week of egg development, or even earlier, and in the larval stages the heart and blood
vessels have acquired the same general relations that we find in the adult.

The lobster at first possesses 19 pairs of filamentous gills distributed as in adult
lobsters. The podobranchs are rudimentary, as are also the gill separators or epipodites,
which are minute reniform plates exposed below the free border of the carapace. In
the second stage these plates are taken completely into the gill chamber and the
rudimentary gill of the eighth somite appears, which completes the branchial formula
(see p. 246).

The nervous system of the lobster is highly developed in the larva and indeed
before hatching, as shown by the admirable researches of Allen, (2), and brain, nerve

NATURAL HISTORY OF AMERICAN LOBSTER

335

cord, motor and sensory elements, as well as the complex stomato-gastric system, have
essentially the same relations as are found in an adult animal.

Natural food of the larva. — It is not to be doubted that the incessant activity of this
larva, which apparently knows no rest day or night, is needed, as Mead remarks to

Fig. 40.— Swimming attitudes of young lobsters in the first free stages; a, lobster swimming with body bent in the
usual quadrant form, the head directed downward and often at a greater angle; the swimming branches (and the perma-
nent limbs rather more than here shown) directed backward, in “posterior” position of Hadley; resulting movement
upward and backward; b, young lobster playing cannibal, swimming astride the carcass of another, which it has nipped
at the junction of the carapace and abdomen and holds with its prehensile legs; c, swimming with the thoracic legs
directed forward; in “anterior” position of Hadley; resulting movement upward and forward; dy rising position
occasionally assumed; e, slowly moving or “floating” position sometimes observed; /, lobster “standing on head,”
apparently probing the bottom with rostrum, but really too weak to rise.

bring them into contact with the minute suspended bodies upon which they feed. All
the rearing experiments that have been conducted by Mead and others with any degree
of success during the past 15 or 20 j^ears, whether in Europe or the United States, have
clearlv shown that the larvae must have their food suspended and in fine particles; the

336

BULLETIN OF THE BUREAU OF FISHERIES.

water must be gently agitated so that larvse will not settle and become smothered in a
mass of decomposing food and sediment at the bottom.

The natural food of the larval lobster consists of minute pelagic organisms, whether
animals or plants, which through their own movements or their lightness remain sus-
pended near the surface, such as diatoms and other protophytes, copepods, the larvae
of crustaceans, echinoderms, worms, and mollusks, the floating eggs of fishes, and, in fact,
any member of the pelagic fauna which comes into their zone and is not too large for
them to master.

The young lobster does not show, however, a very precise discrimination in its food.
It will snap up almost any moving object, living or dead, which it is able to seize and
swallow. Thus I have found in the stomachs of the older larvae vegetable fibers, the
scale of a moth or butterfly, and fine granules of sand.

An examination of the stomachs of a number of larvae which were reared in aquaria
to the fourth and fifth stages, when they measured 13 to 14 millimeters in length, revealed
the following substances: (1) Diatoms in abundance, chiefly Navicula and the long
tangled ribbons of Tabellaria; (2) remains of Crustacea, probably parts of young lobsters;
(3) bacteria in great numbers; (4) cotton and linen fibers and parts of algae; (5) amor-
phous matter, with sand grains. The sediment of the jar contained the same species
of diatoms in abundance, and amorphous debris similar to that found in the stomach
and intestine.

Analysis of the stomach contents of a lobsterling captured in Vineyard Sound August
12 (length, 15 mm.) gave the following organisms: (1) Parts of crustaceans; (2) diatoms;
(3) shreds of algae. In another young lobster taken at the same time (length 17 mm.)
there were (1) parts of crustaceans, (2) large numbers of diatoms, (3) filaments of green
algae and thin sheets or shreds of vegetable tissue, (4) the scale of a lepidopterous insect,
(5) bacteria, and (6) amorphous matter in large masses. The diatoms and small amor-
phous particles of every kind may be regarded as partly or wholly incidental — that is,
taken in with more important food material.

Williams (279) carefully examined the stomachs of one hundred larval and fourth-
stage lobsters, which were being reared in the hatching bags at the Wickford (R. I.)
station, and were fed with finely chopped clams. Thirty-seven contained copepods to
the amount of 37 per cent of the total quantity of food present, and these favorite
crustaceans were especially abundant in the stomachsof the second and third stage larvae.
Larval lobsters were almost invariably absent from their menu, from which he con-
cludes “ that a lobster in the presence of abundant food will not attack his kind.”

A further discussion of food for artificially reared lobsters is given at the close of this
chapter.

The length of the stage periods and the size attained by the lobster in each are
subject to variations to be considered later: Length of first larva, 7.50 to 8.03 millimeters,
average 7.84 millimeters (of 15 individuals); stage period, 1 to 5 days (Woods Hole,
Mass.); length, 8.2 millimeters; period, 2 to 3 days, which may be extended to 25 days
with the temperature at 6o° F. (Mead and Hadley for Wickford, R. I.)

NATURAL HISTORY OF AMERICAN LOBSTER.

337

Fig. 41. — Second larva, or second swimming stage of lobster in profile. For natural swimming position
hold page sidewise with head of animal down, and consult figure 40 of text. Length 9 mm,, or 0.35 inch.

In habits and color the second larva resembles the first closely, but is distinguished
by its slightly larger size and by the presence under the tail of four pairs of svvimmerets
on the second, third, fourth, and fifth abdominal segments, which appeared as minute
buds beneath the cuticle of the first larva at birth. These appendages lack the swim-
ming hairs, and do not become completely functional until the fourth stage.

48299° — Bull. 29 — 11 22

THE SECOND LARVA.

[Fig. 41.]

Under favorable conditions the first larval stage of the lobster lasts from i to 2
days. Upon molting for the first time after birth, the animal emerges into its second
larval, free swimming stage.

33§

BULLETIN OF THE BUREAU OF FISHERIES.

Slighter structural changes which appear upon closer examination of the second
larva are as follows: The rostrum is broader and its margins are serrated; the sides of the
carapace completely cover the gills and separators; the sixth pair of abdominal append-
ages, the uropods of the tail fan, can be seen through the transparent cuticle as rudiments
at the base of the telson; the stalk of the antennule is divided into three segments as in
the adult, and its inner secondary flagellum, which is present in the first larva as a minute
bud on the lower side of the primary flagellum, is much larger and shows traces of seg-
mentation, while the stouter primary branch bears on its inner margin numerous clusters
of sensory hairs. The long terminal spine of the outer flagellum has disappeared; the
second antenna shows a reduction in its exopodite, the outer leaf-like scale with fringe
of plumose hairs, which progresses with the following molts, and an extension of its
segmented whip or endopodite; the chelae or double claws borne on the first three pairs
of walking legs are more perfect, and those of the first pair, which are destined to become
the big claws of the adult, are perceptibly larger but otherwise similar. Both of the
“great claws” gradually develop into the primitive toothed type, reached in the fourth
stage, with teeth arranged in periods of eight; the primary and secondary spines only
are present in the second larva. (See ch. vn.) Average length of second larva, Woods
Hole, Mass., 9.3 millimeters; extremes, 8.3 to 10.2 millimeters (47 measurements); stage
period, 2 to 5 days; Wickford, R. I. (Hadley), average length, 9.6 millimeters; average
duration of stage period, 3 days; extremes, 2 to 7 days.

The Third larval stage.

[Fig. 42.]

Molting for the second time after hatching, the larva enters upon its third free
swimming stage, in which the exopodites of the six pairs of thoracic legs (segments ix-
xiv) are still functional. In habits, in color, and in general appearance the first three
stages in the pelagic life of the lobster show no striking differences. The third larval
stage, however, is readily distinguished from the second by the larger size of the animal,
the presence of the completed tail fan, and the less rudimentary condition of the swim-
merets upon the second to the fifth abdominal somites. The telson is reduced, though
relatively much longer than the uropods; its terminal border is still incurved as in the
first larva, but its lateral spines are longer. The inner whip in both antennae is rela-
tively larger and distinctly segmented, that of the second pair being considerably larger
than the scale.

The “big” claws, though somewhat larger, still conform to the same type. They pre-
sent a series of uniformly spaced spines, corresponding to the largest teeth of the lock-
forceps or toothed claw of the adult, with rudimentary intermediate spines of the sec-
ond order, or, if the latter are not present, the ducts of tegumental glands only, which
mark their future position, may appear on the surface of the shell.

Like the earlier larvae, they swim with head pointed downward, and with incurvated
tail when rising, falling, or moving either forward or backward in the water, and
they dart rapidly backward by sudden flexions of the tail. Yet Hadley observes that

NATURAL HISTORY OF AMERICAN LOBSTER.

339

toward the close of this period they become more sluggish, as if already affected by those
profound changes which at the next molt deprive them of their rowing organs and start
them upon a new career. Upon the bottom, however, the third-stage lobster is nearly
as helpless as at an earlier period, and while it may make the attempt to steady itself
upon its legs, it can not long maintain an upright position. Its future balancing organs

Fig. 42. — Third larva, or third swimming stage of the lobster, drawn to a scale reduced from that of figures 34
and 41. See legend of figure 34. Length 11.1 mm., or 0.44 inch.

are still in an undeveloped state. The swimmerets are now fringed with short rudi-
mentary setae, but do not come into full play until after the next molt.

As Hadley has pointed out, at birth the larval appendages are less concentrated in
the head region than in the adult state, and this is most noticeable in the maxillipeds,
the exopodites of the third pair of which are used for swimming. From the first stage

340

BULLETIN OF THE BUREAU OF FISHERIES.

onward there is a gradual forward movement of the appendages — maxillae, maxillipeds,
and pereiopods — until the fourth stage, when they attain essentially their adult condi-
dition. Average length of third larva, Woods Hole, Mass., ii.i mm.; extremes, 10-12
mm. (79 measurements); Wickford, R. I. (Hadley for 1904), average length, 11.4 mm.;
stage period, 5 days.

THE FOURTH OR LOBSTERLING STAGE.

[Plate xxxi.]

The young lobster makes a surprising leap at the fourth molt, or the third after
hatching, when suddenly it seems to undergo a literal metamorphosis and to become a
new animal, and when for the first time it truly resembles a diminutive lobster. In form,
color, habits, and instincts it differs strikingly from every preceding stage.

The oars or swimming exopodites of its twelve thoracic legs are reduced to func-
tionless stumps, which as a rule are no longer visible to the naked eye. Yet it still
swims at the surface with greater agility, precision, and speed than at any former stage.
The balancing organs, formerly called the “otolith sacs,” at the base of the first pair of
antennse, are fully developed, and the reeling, uncertain gait of earlier stages is no longer
observed. Nor is the body bent in swimming, but is straight as an arrow, and as the
lobsterling glides swiftly along by the action of its swimmerets, now for the first time in
complete working order, the big claws are extended straight in front of the head and
held close together. While it uses the same organs in swimming as an adult animal,
unlike an adult it swims at the surface and with a relatively much higher rate of speed.
As in earlier stages it darts backward by quick jerks of the abdomen, according to one
observer even jumping out of the water, a feat which it is never again able to perform,
and which is possibly equaled in the higher Crustacea only by certain kinds of surface-
feeding shrimp. The great chelipeds are long, slender, and end in symmetrical claws
of the toothed type.

The incessant and apparently aimless activity of the young in all their swimming
stages has been often remarked. While this activity does not protect them from their
enemies or enable them to stem a current of much strength, it is not useless, for it en-
ables them to keep afloat and thus brings them into contact with suspended food, which
has been found to be an important requisite in every hatchery. It has been further
observed that when at apparent rest the motion of the swimmerets in the third and
fourth stages tends to keep the little lobster from sinking.

Like the larvae, the fourth-stage lobsters continue to feed on copepods and small
pelagic organisms of various kinds, even snapping up floating insects, according to Wil-
liams (27 9), who saw a swarm of lobsterlings seize, drag under, and devour a full-grown
cricket which happened to fall into their tub.

In a number of fasting fourth-stage lobsters, which Williams also examined, the
stomachs were found to be empty or to contain only masses of clam cuticle, which they
commonly reject, from which it appeared that such lobsters, even when very closely
confined in a finger bowl and “hungry enough to eat what they ordinarily refuse, will
not attack one another (unless perhaps one or more of their number is newly molted).”

BULL. U. S. B. F. 1909

PLATE XXXI

A.HoBnJcCo.Balnni0re..

FOURTH STAGE OF THE LOBSTER

LENGTH 14.6 MM.

NATURAL HISTORY OF AMERICAN LOBSTER.

341

Perhaps the most interesting morphological change which appears at the fourth
stage, though by no means the most striking, is the torsion of the great chelipeds, described
in chapter vii. The differentiation of the big claws, which come in time to equal one
half the weight of the entire animal, is preceded by a permanent twist which has chiefly
affected the fifth segment. While the lobster in the fourth stage is limber in every joint,
the fusion of the second and third podomeres occurs shortly after this molt.

Lobsters after the larval period, and preeminently in the fourth and fifth stages, often
exhibit the phenomenon known as “feigning death.” When stroked with any object
or when water is squirted on them with a pipette they will roll over and straighten out
as if paralyzed. Their appearance when in this state is very different, however, from
that of a dead animal. The phenomenon appears to be a somewhat sporadic reflex
response, but it is interesting to find it appearing for the first time when the animal is
about prepared to sink to the bottom, and to assume more fully the habits of an adult
animal. (See 149, p. 184.)

Fourth-stage lobsters when approaching the end of their period frequently go to
the bottom in shallow aquaria, hide under stones or any accessible objects, and even
burrow in mud or sand.

The instinct of fear also appears in this stage and for the first time, associated with
the hiding and burrowing tendencies. These are possibly evoked by the development
of that contact-irritability which, as Hadley remarks, seems to come suddenly into
play toward the close of this period. Burrowing is a kind of behavior in which the
lobster frequently indulges from this time onward throughout life. The burrows serve
a fourfold purpose — for concealment and therefore for protection, as a point of vantage
from which to watch and seize their prey, and probably as a means of avoiding strong
light, especially when adult, and particularly when confined in relatively shallow “parks”
or pounds.

Digging the hole is an instinctive act; but returning to the same burrow of holding
to the same crevice for the purpose of defense, for hiding, or for seizing the prey, so
marked in all the later stages of both young and adults, is a distinct mark of intelli-
gence, a habit of returning to the same spot being formed through association.

An interesting phase in the behavior of the fourth-stage lobster, as described by
Hadley, is its rheotactic response or tendency to head into the current, which, with
its other reactions, will be later discussed.

Color in the fourth stage. — At this period the range of color variation is much greater
than at any previous stage, but color change no longer follows so promptly change in
temperature, in the illumination, or in the intensity of other effective stimuli. The
chromatophores or pigment cells of the skin have so multiplied as to form a continuous
screen to the parts below. The former transparency of the larva is thus reduced in
the same degree that the depth and brilliancy of its colors are enhanced.

The exoskeleton is now reenforced for the first time with considerable deposits of
mineral salts, especially of lime. It is still quite translucent, but of a delicate light-
blue tint, as appears at the molt. The body of the lobster, and the cephalo-thorax in
particular, is studded with sensory hairs. The hair pores constantly increase in number

342

BULLETIN OF THE BUREAU OF FISHERIES.

up to the adult state, when the shell is finely stippled with them, while the setae them-
selves have for the most part disappeared.

Microscopical examination reveals a multitude of minute, closely crowded chromato-
phores in the skin, containing pigments of various tints, chiefly red and yellow. The
color pattern is due mainly to the distribution of these cells; the quality and degree
of color which in the same individual is subject to more or less constant variation,
especially before and after the molt, is determined by the expansion of the variously
colored chromatophores, the contents of the alimentary tract at the moment, and the
variable tints of the underlying gastric glands. The bluish tint and slightly diminished
translucency of the shell, when preparing to molt, has a considerable influence on the
color of the animal as a whole.

The general cast of color may be either (i) yellow and red, (2) red, (3) green, or
(4) green and reddish-brown. In the first instance the carapace is light yellow, trans-
lucent, and sprinkled with red chromatophores. The abdomen and large chelae are
reddish-brown, and there is a quadrilateral yellowish -green area on the terga of the
fourth and fifth abdominal segments. In the red individuals the animal is bright red,
especially on the abdomen and large chelae. The carapace is yellowish, spotted with
red, and the abdomen is marked in the way just described. In the green variation the
whole animal is bright green. Bright-green areas are noticeable on the abdominal
terga as before, and upon the hinder portion of the carapace. There is also some brown
pigment on the large chelae and tail fan. In the fourth variety the abdomen and chelae
are rich reddish-brown, with light peacock-green on the terga of the abdominal rings,
as is commonly seen, and on the carapace next to the abdomen. The rest of the cara-
pace is greenish-brown. The characteristic tendon marks on the carapace in this and
in all subsequent stages define the areas of attachment of certain tendons or muscles to
the shell. They become most conspicuous after the fifth or sixth molt. Average length
at fourth stage, Woods Hole, Mass., 12.6 mm.; extremes, 11-14 mm. (64 measure-
ments); stage period, 10-19 days; Wickford, R. I. (Hadley for 1904), average length,
13.5 mm.; stage period 12 days.

THE FIFTH STAGE.

The lobsterling which has not made its descent to the bottom at the close of the
fourth stage continues to swim at the surface until the end of its fifth period, but
whether pelagic or an inhabitant of the bottom its behavior closely tallies with that
manifested in the preceding stage under similar conditions. Hadley has shown, how-
ever, that fifth-stage lobsters exhibit a stronger repugnance to light and a greater
tendency to seek sanded areas and to burrow.

The structural changes which the lobster undergoes in passing from the fourth to
the fifth and again from this to the sixth stage are often so slight as to be unrecogniz-
able by anyone who has not followed each stage under the microscope molt by molt.

The salts of lime and the pigment which begin to appear in the shell at the fourth
stage increase, and the carapace is in most cases fairly opaque, excepting immediately

NATURAL HISTORY OF AMERICAN LOBSTER.

343

after a molt, when, as often happens in crustaceans, the body for a time becomes quite
translucent. From this period onward the color of the lobster is mainly due to shell
pigments which are subject to change within certain limits, and are due to the direct
activity of the chromatophores of the underlying soft skin. Every chromatophore
at the surface of the skin stamps its image and counterpart upon the hard, unyielding
shell.

The characteristic colors of the fifth stage are seal brown or maroon, or some com-
bination of brown and green, which bring into strong relief certain snow-white or cream-
colored spots on the body and chelipeds. The carapace at this stage presents four and
sometimes five prominent white spots, the tendon marks already referred to, two on
each side and one crossing the middle line of the back just in front of the cervical groove
and in contact with it, marking in part the area of insertion of the posterior gastric
muscles. Of the lateral spots the larger is a circular or oval disk-like impression below
the cervical groove and in contact with it, while the smaller spot above the groove
marks the tendinous insertion of a small muscle. From this time onward it is a constant
character of the carapace, although it gradually pales and ceases to be prominent.
Another triangular tendon mark which later becomes noticeable and remains through-
out adult life lies just above the level of the last, at the intersection of the branchio-
cardiac lines and the cervical groove, its angles meeting this line and the transverse and
lateral divisions of the groove or fold.

The external geography of the carapace, which still remains unexplored territory
to a large extent, shows other small spots destitute of hair pores and a great variety of
surface marked by depressions and elevations by the varied distribution of hair pores,
and by spines many of which bear the ducts of tegumental glands, not to speak of the
tendon spots already described, by grooves and larger protective spines, slightly rough-
ened areas of muscle-insertion which are prominent just behind and in front of the
transverse division of the cervical fold, as well as by areas of absorption which are essen-
tial for the molting process and are developed in correlation with the gradual deposition
of mineral salts in the shell, such as the median stripe and the scalloped edges of the
gill-covers. (For adult conditions see chapter vi.)

Further, the pleura of the first abdominal somite are snow-white, while the tips of
the big claws, the rostrum, and the blades of the propeller or tail fan are washed with
dull white or cream color. A light spot is also sometimes seen on the fourth segment
of the great chelipeds.

It should be clearly recognized that here, as at every other stage, the color is subject
to a considerable range of variation even in the same individual, due in a large measure
to periodic changes involved in molting, to the temporary effects of light, and possibly
to food and to other causes. At the crisis of the molt the little lobster is capable, as we
have seen, of some quite chameleon-like performances.

But slight morphological changes are noticed in the fifth stage; the antennse are
extended in length, the big claws have become somewhat shorter and thicker, and it is
common to find that the dactyl is bent so that the edges of the toothed forceps do not

344

BULLETIN OP THE BUREAU OF FISHERIES.

meet. The microscopical rudiments of the swimming exopodites have been further
reduced but do not, as a rule, wholly disappear until the sixth stage. Average length
at fifth stage, Woods Hole, Mass., 14.2 mm.; extremes, 13. 4-15 mm. (15 measurements);
stage period, n-18 days; Wickford, R. I. (Hadley for 1904), average length, 15.5;
stage period, 9.5 days.

THE SIXTH STAGE.

[PI. XXXII. ]

The sixth-stage lobster resembles the preceding stage in all essential respects both
in structure and behavior, barring the fact that apparently all or nearly all animals
in this period are bottom inhabitants. In color the two stages are nearly identical
and subject to a similar range of variation. The tendon marks, and the cream-colored
or dull-white spots on the tips of some of the appendages, which begin to show as early
as the fourth stage, are even more pronounced than before. There is a prominent
light spot at the distal extremity of the fourth podomere of the great chelipeds, as
already mentioned for the fifth stage.

The modified abdominal appendages of the first abdominal somite commonly
appear in the fifth or sixth stages as minute tubercles or buds, which at first lie upon
the sternal surface across the long axis of the body, thus facing each other or pointing
toward the middle line. After segmenting into two divisions, which in some cases
does not happen until the eighth stage, this appendage becomes bent downward until
it stands at nearly right angles with the underside of the tail. I was not able to deter-
mine the sex by the abdominal appendages alone until the tenth stage, but Hadley
(124) maintains that this distinction can be made in the eighth or ninth stages, or even
as early as the sixth or seventh stages, by means of the position of the openings of the
sexual ducts. My material did not enable me to fix the sex by means of these ducts
earlier than the eighth stage, but this was not extensive, and it can not be doubted
but that in all such matters considerable individual variation exists.

The development of the crusher type of claw or the transition from the symmetrical
to the asymmetrical condition of the great chelipeds begins in the sixth or seventh
stage, and is marked by a blunting to be later followed by a fusion of the teeth to form
crushing tubercles, but the change proceeds very slowly and is not conspicuous for
some time. The future crusher gains at first in girth or breadth rather than in length
(see ch. vii, p. 271). Average length at sixth stage, Woods Hole, Mass., 16. 1 mm.;
extremes, 16-17 mm. (12 measurements); stage periods, 14 days. Wickford, R. I.,
average length, 18.6 mm. (12 measurements); stage period, 12.7 days.

THE SEVENTH STAGE.

The seventh stage is sometimes distinguished from the sixth period, as already
remarked by the first noticeable differentiation of the crushing and toothed claws, but
aside from this there are no characteristics in size, form, or function by which this and
subsequent stages can be distinguished with certainty unless one has watched and
recorded every molt.

BULL. U. S. B. F. 1909

PLATE XXXII

SIXTH STAGE OF THE LOBSTER

LENGTH 16 MM.

NATURAL HISTORY OF AMERICAN LOBSTER.

345

The seventh-stage lobsters keep as steadily to the bottom as the adults, and in
crawling about make use chiefly of the last three or four pairs of thoracic legs. The
large claws and smaller chelate legs are often extended forward in front of the head.

In the case of a lobster which was observed to molt from the sixth to the seventh
stage the body was translucent, the general color being reddish brown, with a slight
tinge of green on the carapace. The large claws were of a bright terra-cotta color.
There was a whitish crescentic spot at the cervical groove on the back, and the char-
acteristic tendon marks on each side of the carapace were as prominent as in the sixth
stage. The pleura of the first abdominal somite were also snow white, and the uropods
were tipped with cream color.

At the seventh stage pigment has been deposited below the enamel layer of the
cuticle in an amount which, though at first very slight, increases with every molt and
thus makes the color pattern more and more complex.

According to Hadley ( 124. ) the color of the seventh stage is usually and charac-
teristically pure slate, becoming darker during the progress of the period, showing
further the modifications of blue slate, green slate, and cream slate. The white spot-
tings, as I have frequently observed, show a tendency to become creamy or buff in
color in contrast to their porcelain-like whiteness in the fifth and especially in the sixth
stage.

I have recorded numerous observations to show that the same animal may undergo
no inconsiderable changes of color during the stage period. The color at this time is
due to the pigments of the changing cuticle and to the changing pigments of the soft
skin beneath it. With the advance of the stage period a new cuticle or shell is grad-
ually formed beneath the old, which is later shed, with the tendency to become darker
or more opaque. The color is also affected in some degree by any stimulus or change
of the physiological state which affects the more responsive chromatophores of the soft
skin.

It is therefore a difficult matter to standardize these ever-changing color effects,
and not possible unless the animals are compared in the same stage period, immediately
after molting, and under similar physical conditions. It is certain that the activity of
the chromatophores is not dependent upon the direction or intensity of the rays of
light alone, but rather more, as recent experiments seem to show, upon the physiological
states, which follow upon complex and little understood changes.

Further, the act of molting by the stimulus sent into the chromatophores will
sometimes bleach a brilliant animal into a pale shadow of its former self, as I have
witnessed in the adult shrimp Alpheus, as well as in the adolescent lobster. Accordingly
I consider it highly probable, if not certain, that the blue-slate or slate color is often
due to the advancement of the stage period and to the peculiar opacity which always
follows upon the development of a new cuticle beneath the old. It should also be
observed that the cast shell, from at least the fourth stage to the present, which veils
the brighter colors of the new cuticle, is blue, suffused at this time with green and
brown in its pigment layer.

346

bulletin of the bureau of fisheries.

Hadley remarks that the adult structural type is possibly reached in the ninth
stage, and the adult color pattern in the eleventh. Inasmuch as single structural
characters, such as the differentiation of the big claws, are by no means regular or
invariable in their appearance, we should hardly expect to find the sum of such char-
acters expressed at a definite molt, which after all is but an incident of growth. Even
at the fourth stage, as Williamson (282) has shown in the European lobster, the swim-
ming organs are not shed in the same degree of completeness in all cases. Far less is
it possible to fix upon any definite stage when the sexual characters and sexual maturity
are reached. The data do not seem to be sufficient to make the determination of aver-
ages very precise. Average length at seventh stage, Woods Hole, Mass., 18.6 mm.;
extremes, 18-19.5 mm. (4 measurements); stage period, 14-21 days; Wickford, R. I.
(Hadley for 1904), average length 22.5 days; stage period, 14.3 days.

THE EIGHTH AND LATER STAGES.

The external structural changes which immediately follow the seventh stage are
very slight and concern chiefly the accessory reproductive organs, such as the differen-
tiation of the seminal receptacle of the female and the first pair of pleopods in both
sexes.

The eighth stage is similar in color to the seventh, but according to Hadley there
is a greater modification of the slate color, with a tendency to develop the blue slate
and cream slate, or, in a less marked degree, the green slate and brown slate. According to
the same observer, the blue color is more pronounced in the ninth stage, when the
prominence of the white or cream colored spots is beginning to wane. It has been
further noticed that in the tenth stage the olive green and olive brown combinations
become more prominent; the spottings are seldom seen, and the dark mottled charac-
ter of the coloring of the adult begins to assert itself. This characteristic mottled
color pattern was still more pronounced in the eleventh stage, when it was apparently
established.

HABITS OF ADOLESCENT LOBSTERS.

From the close of its free-swimming life until the later adolescent period the young
lobster drops out of sight so completely that for a long time its habits during this inter-
val were quite unknown (see J49, ch. xi). After reaching the bottom we know that
many of the little lobsters begin to travel toward the shore, in all probability slowly at
first, but more rapidly when at the age of about 3 months they have a length of 1 Ft inches,
more or less.

The instinct of fear, suddenly developed in the fourth stage and present at all later
periods, prompts the little animal to display great caution in all its movements, and to
hide under stones or in the crevices of any protecting object whenever danger assails it.

Whenever the lobster sinks in very deep water, as must often be the case, it possibly
gradually moves shoreward. At all events many adolescent and small lobsters are
found along the rocky shores of bays and small inlets, where they apparently remain
until driven out by ice. These small lobsters live under stones and submerged rock

NATURAL HISTORY OF AMERICAN LOBSTER.

347

piles, the tops or surfaces of which are sometimes laid bare at unusually low tides in
fall, when they may be found by digging and turning over the stones, at depths of but
a few inches at low water, but where at the flood the sea rises to a height of 5 feet or
more. The smallest, from about to 3 inches in length, go deep down among the
loose stones, where no enemy is likely to reach them. At a later period, when from
3J2 to 4J2 or 5 inches long, they issue from their retreats more freely and explore the
bottom with greater boldness. They also dig caves under stones, from which, as at an
earlier period, they stealthily crawl in search of prey, but quickly return when an enemy
appears. We have seen that this characteristic burrowing instinct develops as early
as the fourth stage.

As the lobster increases in size it becomes bolder and retires farther from the
shore, but it never loses its instinct for digging nor abandons the common habit of
concealing itself when the necessity arises.

A LOBSTER 413 DAYS OLD.

As is well known, size, whether of lobsters or of mankind, is not a certain criterion
of age. In the crustacean it depends upon the number of molts successfully passed,
while unfavorable conditions tend to lengthen the molting periods. Some of these
conditions will be considered in a later section. This was well illustrated by the young
lobster whose history follows. This animal was reared in a small glass aquarium at
Woods Hole, Mass., and was fed with minced clams and the eggs of the lobster and cod.
It lived from June 20, 1893, until August 6, 1894, when it had attained the length of
36 millimeters (1.44 inches).

In its final stage the colors of the animal had apparently reached the limit of their
brilliancy and the mottled color pattern was as complex as in an adult animal. The
body was of a light umber color freely speckled and mottled with darker tints. The
appendages were reddish brown and slightly translucent. Small light spots or suffus-
ions were found in certain parts of the body; the tendon marks, corresponding to those
characteristic of the fifth and later stages, were prominent, the round spot just below
the cervical groove being over a millimeter in diameter; the pleura of the first abdominal
somite were snowy white, while the free edges of the segments of the body and of the
appendages were bright blue; the large chelae were white tipped. The openings of the
oviduct were plainly visible, while the lips of the copulatory pouch or seminal receptacle
were not yet closed. The color of the appendages on the under side was light reddish
brown, and the tail-fan was of the same hue, edged with deep red; the big claws, which
were tufted with setae at their tips, showed but little differentiation. The compound
eyes had acquired the large size and prominence of the later adolescent stages.

WHEN DOES THE YOUNG LOBSTER GO TO THE BOTTOM TO STAY ?

Over 15 years ago I raised the question which is now placed at the head of this
section, and answered it in a tentative way, but its importance seems to have been
underestimated, for it has received little attention from other workers up to the present
time.

348

bulletin of the bureau of fisheries.

It was shown that young lobsters did not uniformly make their descent to nether
regions during the fourth stage or even at its end, and that the swimming period often
lasted to the fifth stage, probably until its close, and possibly into the sixth stage.
I have records of young lobsters captured under natural conditions at the surface of
the sea (see 149, table, p. 187), varying in length from 15 to 18 millimeters. The
largest, taken 7 miles southwest of No Man’s Land, near Marthas Vineyard, 18 milli-
meters long, was probably in the fifth stage, though possibly in the sixth, as seemed to
me very likely at the time. Hadley’s measurements for Wickford (R. I.) lobsters,
which average much higher than those obtained by me at Woods Hole, Mass., are for
the stages in question as follows: Fourth stage, average length, 13.5 millimeters
(extreme, 15.5 mm.); fifth stage, average length, 16 millimeters (extreme, 18 mm.,
two records only); sixth stage, average length, 18.8 millimeters (extreme, 24 mm., one
record). (See also later measurements quoted above.) The average length for lobsters
raised in aquaria at Woods Hole in the same stages are as follows: 12.6 millimeters
(extreme, 14 mm.); 14.2 millimeters (extreme, 15 mm.); 16.1 millimeters (extreme,
17 mm.). Inasmuch as size is a very unsafe criterion of either stage or age, it can
not be said that at present there is any satisfactory evidence that the American lobster
remains at the surface beyond the fifth stage. It is interesting, however, to notice a
record by Meek (200) of the capture by surface net of a young specimen of the European
lobster, which measured 20.5 millimeters (-j-f inch), at Alnmouth Bay, Northumberland,
England, in the afternoon of September 7. Its age was estimated at 2 months. Now
according to Ehrenbaum ( 8j ), whose work was conducted at Helgoland, such a lobster
should be in either the sixth or seventh stage and upward of 61 or 87 days old,
respectively (sixth stage, length, 18-20 mm.; seventh stage, length 21-22 mm.). We
should therefore hesitate to affirm that in the American form the swimming life at the
surface is never extended to the sixth stage.

The experiments of Hadley and others on the reactions of the larvae show that the
light-shunning, bottom-seeking, and hiding tendencies begin to assert themselves in
animals artificially reared toward the close of the fourth or else in the fifth stage.

The bearing of this question upon the artificial propagation of the lobster is very
evident, for, if a considerable number of fourth-stage lobsters remain suspended at the
surface, the careful rearing to this stage and subsequent liberation in the sea is only
feeding the fishes. A small force of predaceous tautog, or cunners, would play havoc
with myriads in a short time. As we remarked in 1895, “the problem of the artificial
propagation of the lobster will be solved when means are devised by which larvae, after
hatching, can be reared in inclosures until the fifth or sixth stage, when they can take
care of themselves.” This time limit should have been modified to read “until they go
to the bottom.” The lack of precision which the lobster displays in his desire to
discover the bottom is very disappointing, but it seems evident that liberation of the
carefully reared young at the very beginning of the fourth stage is only to court disaster,
with the attendant waste of time, money, and labor.

NATURAL HISTORY OF AMERICAN LOBSTER.

349

FOOD AND CAUSES OF DEATH IN ARTIFICIALLY REARED LOBSTERS.

The yolk of hard-boiled eggs, crushed crab, boiled liver, minced fish, beef, lobster’s
liver, the soft parts of clams, and menhaden have all been tried as food for young lobsters
by different experimenters in America and Europe with varying degrees of success.

Emmel (95, a) in a series of experiments upon the rate of molting of 90 selected
lobsterlings which had reached the fourth stage on the same day, and which were
divided into lots and were fed on different foods, obtained the following results: Beef-
fed lobsters advanced to the fifth stage in an average period of 11.2 days; when fed on
minced muscle of soft-shelled clams, in 11.3 days; on shredded lobster muscle, in 11.5
days; on shredded fish, in 11.7 days; on beef liver, in 12.3 days. While his tests
showed a slight advantage for the beef fed over those supplied with clams, the lot
which received no food other than the natural plankton of the water were twice as long
in passing to the fifth stage, or 24.6 days.

In the experiments on the artificial rearing of the lobster conducted at Woods Hole,
Mass., bv the United States Fish Commission in 1902, the flesh of the menhaden, which is
saturated with oil so that it does not readily sink, was found to answer admirably as a food
until many of the larvse began to sicken and die. The fish were shredded in a meat grind-
ing machine, and a teacup full of this finely triturated flesh taken twice daily was found to
meet the needs of about 5,000 larvae. The voracious young can hardly be fed too much,
provided the waste is not allowed to accumulate in the rearing tanks or bags, and as they
grow older their ration must be increased. In June it was noticed that many of the
menhaden-fed fry in the rearing bags were attacked by a fungus, which Gorham (121)
thought was attributable to the oily fish upon which the young had fed. According to
this observer, the mycelial filaments of this fungus spread from the point of infection
until all the animal’s tissues were destroyed and the lobster’s body was reduced to a
chitinous shell packed full of the mycelium.

In 1893 I described a case in which a parasitic fungus, probably belonging to the
family Chrytridiacese, had attacked the late egg embryos of the shrimp Alpheus, a relative
not far removed of the lobster. In this case the eggs were crammed full of the encysted
parasite.0 No internal egg parasites have yet been reported for the lobster.

The chief causes of death in the artificially reared lobsters are organic sediments,
cannibalism, which is caused chiefly by overcrowding or a lack of proper food, and the
exceptional fungus growths under the conditions of feeding referred to above. The sedi-
ments cling to the hairs of the appendages, interfere with the locomotion of the larva,
and send it to the bottom, thus cutting off its supply of food. In this way it becomes
crippled, and, being too weak to molt, it usually starves to death. Various algae, bacteria,
Stalked protozoa, and diatoms occur in these sediments, but the chief offenders are
diatoms.

Gorham (121), who has made a careful investigation of the causes of death in arti-
cially hatched fry, names 24 species of diatoms which were found on lobsters reared at

a For figures and description, see appendix u. ch. v, of The embryology and metamorphosis of the Macrura, Memoirs
National Academy of Sciences. Washington, 1893.

350

BULLETIN OF THE BUREAU OF FISHERIES.

Woods Hole, of which the four most common species were Licnwphora tincta, Diatoma
hyalinum, Rhabdonema arcuatum, and Tabellaria unipunctata, named in the order of their
relative abundance.

I have seen the fry almost buried out of sight by diatoms in neglected jars at Woods
Hole, especially by Tabellaria , which at times was very abundant and destructive.

Other organisms found by Gorham to infest the young lobsters at Woods Hole were
a filamentous green alga and a stalked protozoan, Ephelota coronata, which was more
abundant in the waters of Wickford, R. I.

Cannibalism may be reduced by supplying the young with proper food, by agitating
the water and thereby keeping both the young and their food suspended, and by avoiding
overcrowding. The growth of diatoms can be checked or prevented, according to
Gorham, by filtering the water; by selecting a suitable station for the rearing apparatus
where diatoms do not abound, and where the temperature is high or most favorable for
hastening growth and molting, by which the little animal escapes for the time being at
least from all its troublesome messmates; by frequent cleaning, coating, or renewal of the
rearing bags; and by reducing the light and thus hampering the diatoms by cutting down
their food supply. (Compare, p. 281.)

THE SIGNIFICANT FACTS OF LARVAL AND LATER DEVELOPMENT.

Some of the most important facts concerning the larval life of the lobster may now
be summarized:

(1) The young are hatched in great numbers, 5,000 to 100,000 eggs or young being
produced at one time by a single animal according to its size, the number increasing
rapidly in proportion to the cube of the body length or to the total volume of the body.
This leads us to expect great destruction of the young in nature, an expectation which is
unfortunately realized. It is a vulgar error to assume that the abundance of this ani-
mal or of any other species is proportional to the number of young born, since it neglects
the equally important question of the destruction of the young or their rate of survival.
The rapid rise in production beyond the 10-inch size proves that the older the animal the
more valuable it becomes for reproductive purposes, barring the question of sexual
decline, which is of little importance in an animal so seldom permitted to grow old.

(2) The larvae are hatched at the bottom of the ocean in relatively shallow water at
night or in early morning. A molt occurs at the time of hatching; parental instinct
ceases; the larvae are soon dispersed, and leaving the bottom lead a free-swimming,
pelagic existence for a period of from 3 to 6 weeks (see p. 348), according to circumstances.
Summer eggs on the coast of Massachusetts are hatched from May 15 to July 15, the
majority being extruded in June.

(3) The movements of the larvae in a natural state are not fully understood. Under
certain conditions they rise toward the stronger light at the surface; under other condi-
tions they retreat from the light, sinking to greater depths. They have been taken near
the surface in the townet in both strong sunlight and at night, both with and without
the aid of artificial light. At the present time they are seldom found at the surface under

NATURAL HISTORY OF AMERICAN LOBSTER.

351

any conditions. Since the young feed upon moving or suspended prey, their life can not
be spent far from the surface. Their behavior at any given time is the resultant of all
the conditions which affect them at that time, and therefore varies with the varying
conditions of their life. The rarity of the larval lobsters at the surface in areas where
the adults are known to abound may be ascribed to the following causes: (1) Wholesale
destruction of the breeding animals, which has caused the present depletion of the
fishery; (2) the great destruction of the young, which must take place under natural con-
ditions; (3) the wide dispersal of the young by tides and currents which their swimming
habits favor, and (4) the variable character in their reactions or movements, leading to
a variable or irregular vertical distribution.

(4) The food of the larval lobster consists of minute pelagic or floating organisms,
such as copepods, crustacean larva:, algae, and probably to some extent protozoa. The
stomachs of young lobsters taken at sea have been found to contain fragments of crus-
taceans, diatoms, algae, fine sand grains, and amorphous matter. They seem ready to
attack and seize any small moving object, living or dead, which they are able to master.
Since they follow moving objects like copepods by sight they discriminate to some extent,
but their powers in this direction are slight, and would seem to be unnecessary if they early
acquire the adult habit of regurgitating the indigestible residue of their food.

(5) The preying instinct, which is closely associated with that of pugnacity, is
very strong in young lobsters from the time of birth. Their disposition to attack and
devour one another, as seen in aquaria whenever they are too closely crowded or not
supplied with the proper food, is the obvious result of an indiscriminate instinct to
seize floating objects which are neither too large nor too active. Another lobster is as
good a mark as a floating egg, or as a swimming copepod, which is more apt to elude
them. Indeed they often give chase to crustaceans larger than themselves. The fight-
ing instinct, if we may thus describe the tendency referred to, is closely associated with
the primary instinct to seize and devour, in accordance with which the character of
their activities and the structure of their bodies is distinctly correlated. It is thus
evident that the organic food of the young lobster must be finely divided and floating,
and that crowding in too close quarters can not be otherwise than destructive.

(6) The body of the larva is covered with a cuticle, which includes the lining of the
stomach sac, and at least a part of the intestine. This is continuous with every spine,
seta, or hair with which the body is protected or garnished, as well as with the internal
skeleton which is produced from folds or pockets of the skin. Active growth entails
the shedding of this cuticle, which is cast off in one piece, and the duration of the molting
intervals or stage periods depends on the vigor and health of the individual. Each
molt is a crisis in the animal’s life. If the cuticle is not properly shed, the swimming
hairs can not be properly evaginated, and the animal becomes helpless.

A healthy larva is always clean and transparent, while in a weakened or sickly
one the hairs tend to gather sediment and parasites. Sea water of normal density in
which the plankton or floating population of animal and plant life is properly balanced
and an undue amount of sediment is not present, are important conditions for rearing
the young, and the warmer the water, within certain limits, the more rapid the growth.

352

BULLETIN OF THE BUREAU OF FISHERIES.

At certain points on the coast it may be possible to rear many marine animals
with comparatively little difficulty, or to keep them alive in the adult state for long
periods, while at other places every aquarium may become the grave of all but the
hardiest species or individuals, and that in a short time. The difficulty seems to arise
from the nature of the plankton, and from the tendency of certain prevalent organisms,
such as diatoms, parasitic bacteria and fungi, to increase in an inordinate degree. The
larvae become weakened, and can not pass their molts.

(7) In the fourth stage the young lobster, as if in one bound, seems to justify its
name, to lose its old swimming organs and acquire new ones, to lose the rolling uncer-
tain gait of the larva and to acquire new strength with greater precision and speed. It
loses in large measure its former transparency, and, together with a greater hardness
and opacity of its shell, it gains a far greater brilliancy and variety of coloring. The
fourth stage also marks the rise of new instincts such as fear, burrowing for concealment,
not to speak of far greater pugnacity, and the dawn of intelligence or power of associa-
tion, displayed in the lobsterling’s holding to the same hole or retreat for hiding, to
which it will return repeatedly and will defend with spirit. Perhaps more important
than any of these characteristics is the fact that many of the fourth-stage lobsters
probably go to the bottom and stay there. This at least is their habit when reared in
confinement.

The fourth-stage lobsters seem to swim at the surface more regularly and con-
tinuously than the larvae, and accordingly are more often taken in the net, while it is
evident that the earlier stages must be thousands of times more numerous.

(8) The rate of growth is greatest during early life, and according to Hadley is 18
per cent at each molt at Wickford, R. I., up to the seventeenth stage, when it begins
to slowly decrease. I found the rate to be less in the slightly colder waters at Woods
Hole in the case of artificially hatched and reared young. The time interval be-
tween successive molts is indeterminate, being subject to every change which affects
the physiological vigor of the animal. The advancement of the larva is to be measured
by the number of its molts and not by its age. Under favorable conditions the three
larval stages are passed in 10 or 12 days; the fourth stage lasts as long, so the swim-
ming period may be over in about three weeks, or may be extended to four weeks or longer
when the bottom is not sought until the fifth stage.

The approach of the molt seems to start the lobsterling on its course to the bottom;
accordingly when this is delayed until after the fourth stage, it probably does not often
occur until the approach of the succeeding molt. (See p. 348.)

Chapter XL— BEHAVIOR AND RATE OF GROWTH.

BEHAVIOR OF YOUNG LOBSTERS.

Having considered the general habits of the lobster in its successive stages of
development, we shall now discuss their behavior in more detail.

In the summer of 1894 I tried a number of simple experiments to test the effect
of light upon the movements of the larval lobster. Twenty-five thousand young in
the first stage were placed in the observation pool at the Fish Commission station,
Woods Hole, Mass., in order that their behavior might be watched. The sun was
intermittently obscured by clouds during the greater part of the forenoon. When set
free, the larvae soon swarmed in a large cluster near the surface, where they remained
for a short time. Presently all of them went down to a distance of from 1 to 2 feet,
and some of them to the bottom to a distance of 3 feet more. A lot of small cunners
then appeared on the scene and snapped up the larvae right and left. Two hours later
the remnant were dispersed over the whole pool, a large number remaining close to
the surface. At 1 o’clock in the afternoon the surface on the lee side still swarmed
with larvae. Occasionally one could be seen to attack and drag another down. They
swam with their usual aimless activity, now rising and falling and changing their direc-
tion frequently. The majority of them had now become quite red. Later in the
afternoon nearly all of the little lobsters had disappeared, having been swept out by
the tide or destroyed by the cunners or other fish in the pool.

Various boxes were then constructed to admit diffuse light from above or direct
light through one end, and larvae in the first stage were found to move toward the
source of the light, whatever its intensity. In similar experiments made at another
time this reaction, which then seemed characteristic, was reversed, “showing possibly
that under certain conditions the larvae are negatively heliotropic.” At this time the
subject of animal behavior had hardly emerged as a branch of experimental biology,
with its more exact analytical methods and criteria which have since been evolved.

The experimental work of Bohn (27) on Homarus gammarus and of Hadley
(/ 31) in particular on the American lobster have illustrated the importance of study-
ing the behavior of such an animal throughout the entire course of its development,
and at the same time have revealed the great variety and complexity of the problems
involved. The following paragraphs are little more than a summary and running
commentary on some of their results.

For the analysis of certain problems in behavior the lobsters are unsurpassed,
since with the proper apparatus they may be hatched in unlimited numbers and main-
tained to any required age or stage during the summer months. The results of studies
thus far made show that while the crustacean larvae may respond promptly and in a
definite manner to a certain stimulus, their behavior is complex and essentially variable,
and that at any given point of time it is the result of all the influences at work.

48299° — Bull. 29 — 11 23 353

354

bulletin of the bureau of fisheries.

It is evident from the preceding chapter, as Hadiey has already pointed out, that
the life of the lobster may be divided on the basis of behavior into three periods: (i)
The three larval stages, when the animals frequently swim with head depressed, upward
or downward and forward or backward, according to circumstances, by the use of their
thoracic exopodites; (2) the fourth stage, when the animal is a free swimmer at the
surface, the abdominal swimmerets being now functional, as in the adult; and (3) the
later stages, when the swimming organs are the same, but the animal remains constantly
on the bottom after its final descent in the fourth or fifth period.

REACTION TO LIGHT.

The response of the pelagic larvse of the higher Crustacea to light, as well as
the effect of light upon the growth of these animals, are questions not only of great
scientific interest, but in the case of the lobster of practical importance in view of
the necessity of understanding their behavior in a state of nature and of placing
them as far as possible under natural conditions in the hatchery. It has been
shown in general that swimming larvae of crustaceans, in common with many other
organisms, exhibit two types of response to the light stimulus, known as phototaxis
or reaction to the directive influence of the rays of light and photopathy or response to
changes in the intensity of light. The phototactic response is composed of two ele-
ments or components — the turning and progressive movements or, as Hadley calls
them, the body and progressive orientation; the animal turns so that the long axis of
its body coincides with the path of light, and it always heads away from the source;
this reaction is primary, constant, and typically reflex. On the other hand, the “pro-
gressive” response which follows this stereotyped form of orientation may be positive
or negative — that is, the animal may move upward or downward, backward or forward —
that is, toward or away from the source of light. The photopathic response is also
variable, the animal moving toward or from a more brilliantly illuminated region,
according to conditions.

Thus, according to Hadley, apart from the orientation of the body there is no
constant type of reaction for the larval lobster. The variable responses vary in accord
with changes in the environment of the individual and changes in the individual itself
or its physiological state, and are especially marked at the beginning and close of the
stage periods. While the phototactic response is eminently variable, the photopathic
reaction is usually positive.

In the fourth stage the conditions are somewhat reversed, since in the laboratory
lobsters at this period usually give a negative phototactic reaction, while their photo-
pathic response is at first positive and later negative. Tight-avoiding reactions of
whatever kind are strongly manifested in the fifth stage and may begin at the close of
the fourth. So strong indeed was the tendency to shun the light that the little lob-
sters, as Hadley demonstrated, would even allow themselves to be stranded, with pos-
sible fatal results, rather than to approach the light, and thereby gain deeper water.
It was further shown that at this time also the thigmotactic reaction, or response to

NATURAL HISTORY OF AMERICAN LOBSTER.

355

contact with solid bodies, began to assert itself and thus to modify the previous sensi-
tiveness to light, apparently leading the animal to crawl under shelter and to burrow
in the sand or mud at the bottom.

Previous to the fifth stage an increased intensity of light in certain cases may
reverse the response, while in others it does not. After the fifth stage no reversal of
the response can be effected in this way.

We will now review some of the observations of Bohn on the movements of the
larvae of Homarus gam-mams of Europe, reported in 1905. He believed that the newly
hatched young were immediately attracted to the surface, since they are positively
phototactic. At first they approached the light, while later, at the end of some days,
they moved toward regions of greater obscurity. Upon the swimming movements and
unstable equilibrium of these larvae this observer remarks as follows: The back of the
lobster does not remain constantly directed upward, but is alternately inclined to the
right and left, sometimes as much as 90°. It can likewise tip over by turning on the
long axis of its body. The displacement of the body is effected not by the position of
the longitudinal axis alone, but by that of the vertical axis of the cephalothorax as well.
If the carapace is elevated, the animal both advances and rises; if it is inclined to
the right, the larva advances by deviating to the right, and the more considerable the
rotation the more pronounced the deviation.

In their rolling gait the larvae tend to keep the back turned upward — that is, toward
the surface illuminated by the vast expanse of sky — while the head is bent downward
toward the region of shadow. When this position is maintained the eyes are illumi-
nated in a peculiar manner. At their most elevated points, opposite to the illuminated
surface, there is a lighted area, while at their most anterior ends, which are directed
toward the regions of obscurity, there is an area of shadow.

“All of these observed movements,” says Bohn, “such as repulsion and attraction,
rolling and other rotations, are made with rapidity and precision and have the char-
acter of irresistible movements, according to laws which appear very exact, but which
vary with the physiological states.” Bohn concludes that the larvae are guided in their
movements mainly by the stimulus of light which enters the eyes, and that the eye acts
before the “otocyst” as an organ of orientation.

In regard to the question of any real distinction between the photopathic and
phototactic response, or between the intensity as distinguished from the direction of
light, Hadley remarks that the direction of the light is effective in determining which
eye shall be stimulated most and what parts of both eyes shall be stimulated equally.
In the first instance the long axis of the body is swung into line with the rays, so that
both eyes are equally affected, while in the latter the body is so placed that the anterior
lateral surface of the eyes receive the strongest and the posterior lateral surface the
weakest illumination.

Hadley found that when blinded in one eye the larvte rapidly rotated on its long
axis in a definite direction or performed “circus” movements, moving in circles, toward
or away from the position of the uninjured eye according as the animal was negatively

356

bulletin op the bureau of fisheries.

or positively phototropie. It was also noticed that these reactions were seldom negative
except in the fourth or later stages of the lobster. Each eye is thus apparently connected
with a reflex mechanism which controls the movements of a definite side of the body.

If the light which strikes a larval lobster is suddenly blocked, Hadley found that a
reorientation of the body was usually effected so that the animal faced the former light
source.

Generally speaking the movements of the larval lobsters seemed to Hadley to
support the tropism theory, and to represent simple or complex reflexes, in the
latter case of serial form, and resolvable, with sufficient data, into a number of simple
components.

Both Bohn and Hadley have tested the effects of “screening” upon young lobsters,
or their behavior against white and dark backgrounds, brought to bear upon them
from any direction, and while the results of the observers are not wholly in accord,
Hadley concludes that the larvse orient themselves to the white and black screens or
backgrounds by essentially the identical reflex movements by which they respond to
direct illumination and shading.

In the case of red monochromatic light on a white ground the lobster in the first
stage was found by Hadley to be negatively phototropic, but on a white ground in blue
light positively phototropic. In this respect, moreover, the second and third stage
lobsters responded in the same way, while against black the lobsters retreat from both
red and blue in all their stages.

The fourth-stage lobsters, on the other hand, were observed to rise from black
backgrounds in light of any intensity or color; that is, to display positive phototropism,
and the stronger the light, the more marked was the reaction. Against white also the
fourth-stage lobsters rise to any light except red, from which they tend to retreat.

The older lobsters of the fourth stage did not respond so promptly in a positive
manner, and when preparing to molt they showed a negative reaction; that is, they
sought the bottom, a response commonly assumed in the fifth stage, whatever the char-
acter of the light or background.

The results of Hadley’s experiments were in harmony with observations of the
behavior of the larvae confined in the 12 -foot canvas rearing bags, where they showed
“at all times a marked tendency to sink to the bottom, except perchance at night, when
more active swimming is observed in all the stages. This tendency during the daytime
could not be controlled in any way. At night, however, it was possible to evoke a
seemingly positive phototactic reaction from any of the young larvae in the large canvas
bags. This was accomplished by means of the acetylene light so directed against a
certain area of the white field of canvas that large numbers would at once group them-
selves thickly about the illuminated area, manifesting in the case of the third and the
fourth stages, such an effort to come into the light area that they would often throw
themselves out of the water, causing thereby numerous surface ripples” ( iji ).

NATURAL HISTORY OF AMERICAN LOBSTER.

357

REACTION TO OTHER STIMULI.

The results of galvanic stimulation are particularly interesting, since they appar-
ently represent a fundamental response of living matter, this particular form of energy
being unknown under natural conditions. It was noticed by Hadley (129) that the
young lobsters reacted very definitely to the galvanic current by gathering at the anode.
Under the influence of the ascending current a progressive orientation to the anode
took place, providing the long axis of the body came into certain relations to the current.

Hadley has also described an interesting rheotactic response in lobsters of the fourth
stage, in accordance with which they head to the strong circular current which is main-
tained in the rearing bags or boxes at the fisheries station at Wickford, R. I. Even within a
minute after molting to this stage the lobster would face about and head into the current,
swimming so actively as to make some progress if the force was not too strong. “This
characteristic manner of swimming, says Hadley,” “was evinced in an ever-increasing
number of lobsters, until the whole body of them had passed into the fourth stage, and
then it was a most interesting sight to observe the young animals, with hardly an excep-
tion, heading into the current and as a great phalanx following their circular course —
but, because of the force of the current, backward.”

This rheotactic response is if anything stronger by night than by day. It may be
modified or lost by passing from shadow to full light in the daytime or from darkness to
strong light at night, the phototactic response overcoming the influence to swim against
the current. Rheotaxis is due in some measure to a stimulus which, as Hadley believes,
reaches the nerve centers through the eye. It is gradually lost in the fifth stage.

MOVEMENTS OF THE YOUNG LOBSTER IN A STATE OF NATURE.

We will now review the probable behavior of the young swimming lobsters in their
natural state in the sea, in order to ascertain to what extent experimental work in the
laboratory has enabled us to understand their complex movements. It must be admit-
ted that comparatively little is definitely known through direct observation upon the
subject.

Under natural conditions the young of the lobster, as in many of the higher Crus-
tacea, are presumably hatched at twilight or at night at the sea bottom, their dispersal
taking place in the way already described (p. 327). Possibly under some conditions they
swim to the surface during the night of their birth, while as a rule they may not make
the ascent until stimulated by the light of returning dawn, but remain at the higher
levels for a few days only. This is confirmed by captures with the tow net by both day
and night (p. 331) and by the experiments of both Bohn and Hadley, already recorded.

Then follows a period of greater fluctuation, embracing the latter part of the first
and the two remaining larval stages, during which their movements are variable.
Though still coming to the surface and within reach of the net, their capture in this
way, at the present time at least, seldom occurs under any conditions. Presumably in
shallow waters they even settle at times upon the actual bottom, but their usual beat
or range of movement, especially in deeper waters, is not known. Experiment has shown

358

bulletin op the bureau of fisheries.

that while they tend to hold the body constantly with back to the light source they
may move up or down, back and forth; that is, toward or away from the source of the
stimulus, as a result of a variety of contending and conflicting influences, now one
winning the day, or the hour, now another. The issue may indeed vary from hour to
hour, and one might almost say from moment to moment.

With the wonderful change registered at the beginning of the fourth stage, the
young lobster mounts to the surface and holds more persistently to it than ever before,
at times even jumping out of the water like a shrimp, though having discarded its larval
swimming organs and having brought into play the permanent swimmerets under the
tail. Every observer is agreed that of all the free-swimming stages the fourth is that
most commonly taken at the surface of the ocean, and especially in the brightest sun-
shine. This surface-swimming habit has further been observed by every experimenter
who has reared these young or turned them loose into the sea. At this point the experi-
mental testimony seems to conflict with the natural behavior of the lobsterling, since
during the early part of its fourth stage it has been observed to avoid the light. The
explanation would seem to be that this, like most of its similar reactions, is subject to
reversal, under conditions which are not as yet fully understood, but which, as Hadley
suggests, may be due to an increased intensity of the light stimulus or to an impulse
which leads it to seek its food at the upper levels of the water.

At the close of the fourth, or at some time probably near the end of the fifth period,
the little lobster makes its complete and final descent to lower regions. (Compare p. 348.)
Thereafter the bottom of the sea becomes its fixed abode, which it seldom or never leaves
unless snapped up by an enemy, or in after years it is hauled to the surface in a lobster pot.

In the fifth and all later stages the light-shunning tendency becomes more and more
pronounced, but it can not be said that it is never subject to change, for more than
once I have seen adult lobsters exploring the bottom in shallow water on sunny days.
Yet their avoidance of strong light and their impulse to hide and to burrow after the
fifth stage is fairly constant. In a word, their behavior is no longer essentially vari-
able, but is in a measure stereotyped.

VARIATION IN THE RATE OF GROWTH AND DURATION OF THE STAGE RERIODS.

The following table shows the size and age of lobsters during the first eleven stages,
and is based upon data obtained at different points on the coast under different condi-
tions of temperature upon a varying number of individuals and by different observers.
New measurements of any number of individuals made under approximately similar
conditions would possibly give a different result, but this difference would not be great.

I found that the fourth stage was reached at Woods Hole on the average in 14
days, while Mead has determined this period for Wickford, R. I., to be a little over 12
days, the average duration of the first three periods varying from 9 to 16 days, with an
individual variation of 3 to 7 days, according to the temperature and other conditions.

Assuming that the lobster goes to the bottom to stay at the close of its fourth stage,
the pelagic life of the Woods Hole lobsters would be about 30 days, while at Wickford

NATURAL HISTORY OF AMERICAN LOBSTER.

359

it would last 23 days, or a little over 3 weeks. Assuming that the bottom is not defin-
itively sought until the close of the fifth stage, the free swimming life at Woods Hole
would last 46 days, or a little over 6 weeks, and at Wickford about 30 days.

Table; ii. — Average Size and Duration of Stage Period in the First Eleven Stages.

Stage.

Wickford, R. I.
(Hadley).

Woods Hole,
Mass.

Average

length

(milli-

meters).

Stage

period

(days).

Average

length

(milli-

meters).

Stage

period

(days).

8. 2

2. O

7.8

i-5

9. 6

4.0

9. 2

2-5

11. 4

5-o

11. 1

2-8

13- 5

12. 0

12. 6

10-19

15- 5

9- 5

14. 2

11-18

18. 6

12. 7

16. 1

22. 5

14-3

18. 6

26. 5

16. 0

21.03

3 2- 1

24- 5

23. 23

42. 9

Assuming, further, that under natural conditions the molts are passed more rapidly,
and that the bottom is sought some time between the close of the fourth and of the fifth
stages, the pelagic life will be found to cover a period of from 3 to 4 weeks.

CONDITIONS WHICH DETERMINE THE RATE OF GROWTH AND THE DURATION OF STAGES.

The length of the stage period or the period between molts from first to last depends
upon (1) intrinsic and (2) extrinsic causes. Among the intrinsic causes the following
must be considered: (a) Inherited characters or the individual constitution, which
gives a certain bent or direction to activities and limits their scope, and ( b ) acquired
characters, such as the loss of limbs, which is certain to retard the rate of growth of the
body as a whole by diverting energy to the regeneration of the lost parts.

Thus if the fighting and preying instincts, due to inheritance, are stronger in larva
A than in larva B, A will get more food, grow faster, molt sooner, and, its inherited cap-
ital being equal in all other respects, it will distance B in the race from the start and,
barring mishaps, forge ahead at every step of the way. The early advantages gained by
A are cumulative in their effects. The parable of the talents is applicable even to the
lobsters, and the laggard in the race, though of the same age, may not attain one-half,
or even one-quarter, of the strength of its more strenuous rival, and will be fortunate
if it is not cut into pieces and devoured, a contingency quite likely to happen when
its running mates are crowded or underfed.

Among the acquired characters are to be reckoned any weakness which may be due
in the first instance to congenital defects, such as imperfect or undersized eggs, acci-
dents like the loss of a limb, mutilations of any kind, which, as Emmel (90) has shown,
increase the stage period and therefore diminish the rate of growth, or parasitism which
may be encouraged by a lowered vitality or improper food.

360

bulletin of the bureau of fisheries.

Of extrinsic causes the most important are (a) food of the proper sorts, (6) changes
in temperature, a powerful factor under ordinary conditions, and (c) changes in light,
to which the lobster, whether as larva, adolescent, or adult, is very sensitive from infancy
to old age.

Every stage period culminates in molting, a result and expression of growth which
is subject to the causes above enumerated and therefore indeterminate. Consequently
the rate of growth in lobsters is subject to wide variation. Every individual has its
own rate, which may vary from that of others or from its own rate at a later period of
life by ioo per cent, and which may be different at different times of the year and at
different places, as well as different at corresponding times in different years at the
same place. Moreover, beyond a certain stage the rate of growth varies in the sexes.
Variation in the rate of growth is far from uniform in man and the higher animals, but
it is not subject to such rapid changes and wide fluctuations.

Notwithstanding the drawbacks and difficulties of the problem, it is possible to
determine the average rate of growth and age of maturity, provided our statistics are
ample, which is not the case at present except for one or two points on the coast.

RATE OF GROWTH AND AGE AT SEXUAL MATURITY.

In 1895 I made the first systematic attempt to determine how long it takes an
adult marketable lobster to grow, and remarked: “It is impossible to answer the ques-
tion with certainty, since complete data for solving the problem have not been gathered.
We can, however, give a tentative answer which is probably not far from the truth.”

It was further pointed out that in order to ascertain the average age of a lobster
io}4 inches long (weight 1J4 pounds) it would be necessary to know, first, the number
of molts which the animal had passed through, and, secondly, the time interval between
each molt. We showed that the number of molts could be approximately determined
by certain means discussed. The time interval could only be ascertained by keeping
the animals alive for a period of years and carefully recording their growth. Both of
these factors, as we have already seen, are highly variable quantities. Thus, to give
further examples, the length of a certain yearling lobster which was raised from the egg
was only 36 millimeters, while three other lobsters measured from 35 millimeters to 51.8
millimeters when only 5 months old. Even more striking individual differences have
been given by Mead (195) and Hadley ( 126 ); two of Professor Mead’s lobsters each 4 >2
months old (June 1 to October 7) measured about 55 millimeters and 30 millimeters,
respectively, the smaller being not much larger than one of the big claws of the former.
Of three lobsters figured by Hadley, each having attained an age of x year and 4
months on October 23, 1902, the larger had reached a length of about 120 millimeters
(nearly 5 inches), the smaller but 58 millimeters (about 2 l4 inches). Lobsters that
live in harbors where they find abundant food undoubtedly grow much faster than
those farther from shore and on poor feeding grounds. It could hardly be expected,
moreover, that lobsters kept under artificial conditions would grow as rapidly as when
free in the ocean.

NATURAL HISTORY OF AMERICAN LOBSTER.

361

I also gave a record of the molts of eight lobsters varying in length from 5^ to 1 1%
inches, and found the average percentage of increase (ratio of increase to total length
before molting) to be 12.01. Then using the records of the lengths of lobsters reared
from the first to the tenth stages at the laboratory of the United States Bureau of
Fisheries at Woods Hole, Mass., the percentage of increase for a total of 246 young
individuals gave the percentage of increase as 15.3 for each molt. The table follows:

Table 12. — Actual Length of Lobsters during the First Ten Molts.

Number of molt or stage.

Average

length.

Extremes in
length.

Number of
lobsters
examined.

mm.
7. 84

mm.

7. 50 to 8. 03

9. 20

8-3

10. 2

ri. 1

12. 6

14. 2

13- 4

16. r

18. 6

19- 5

21. 03

19- 75

24- 5

28. 03

26. 6

29- 5

It should be added that the measurements here recorded were not made with this
problem definitely in view, and are therefore uneven in number, and further that the
number of young considered in the last four stages are too small to give satisfactory
results.

Assuming the average length of the first larva at Woods Hole to be 7.8 millimeters,
a table was drawn up giving the estimated length of lobsters during the first 30 molts
as follows:

Table 13. — Estimated Length of Lobsters during the First 30 Molts.

Stage.

Length.

Stage.

Length.

mm.

7. 84

vim.
32. 55
37- 54

9. 04

10. 42

43. 28

12. 02

49. 90

13. 86
15. 98

57- 53
66. 34

l8. 42

76. 49

21. 24
24. 49
28. 23

88. 19

1 1 7. 24

Stage.

Length.

mm.
135- i7

22 .

155- 86

179. 70

207. 20

a 238. 90

h 275- 45

317- 59

366. 16

422. 21

c 486. 81

We called attention to the fact, which has since been verified, that the increase is
similar from period to period during the larval and early adolescent stages. Accord-
ing to Hadley ( 126 ), during the first 17 stages, when the young have reached an age of 2
years and 3 months, the increase per cent is 18.

The frequency of molting or the stage period was next considered with the follow-
ing result: We concluded that during their first year, lobsters as a rule molted from 14

362

BULLETIN OF THE BUREAU OF FISHERIES.

to 17 times, and attained a length of from 2 to 3 inches, with the probability that this
limit was often extended. Examining all the data available at the time we further con-
cluded that the 10-inch lobster was between 4 yi and 5 years old, the higher degree of
probability favoring the smaller number, and had molted from 25 to 26 times. “The
reader is reminded,” we then added, “that this is only an estimate, based, it is true,
upon rather slender data, but upon the only facts which we possess. In future years
some experiments will be made by which this result can be tested.”

The words just quoted were written in 1894; twelve years later the problem of
the rate of growth in the lobster was taken up by Hadley ( 126 ), who has given an
excellent discussion of the question in all its bearings and has supplied many of the data
which were then lacking. His work was conducted at the Wickford hatchery of the
Rhode Island Commission of Inland Fisheries under conditions which the experience of
many years and of many workers has brought to a high degree of perfection. His
results are therefore more complete and more valuable than those of any previous
students.

Hadley’s final conclusions (see 126) so far as general results are concerned do not
differ greatly from those reached by me in 1895, as may be seen by the following com-
parisons: Thus, I estimated that a lobster in the first year of life molted from 14 to 17
times, and reached a length of from 2 to 3 inches; Hadley determines that the yearling
molts 1 2 times and attains a length of 2^8 inches. According to the table (here reproduced
as table 13) the 10-inch lobster has molted from 24 to 25 times and was estimated to
have reached the age of 4 yi to 5 years ; according to Hadley a male 9/3 inches long has
molted 23 times and is 5 years old, while the female of the same length is 1 year and 5
months older. Thus at this juncture the estimates are from one to two molts apart, and
for the male in essential agreement as to age.

Table 14 (after Hadley). — An Estimate of the Rate of Growth of the American Lobster
from Time of Hatching to Attainment of a Length of 224^ Inches.

Stage.

Approximate

age.

Length.

Increase.

Milli-

meters.

Inches.

metos. I-hes.

Per cent.

8. 2

No. 3.

8 !

18. 8

618

iYa,

No. 13

1 year 1 month

62. 0

2 Yt

‘s6.o

No. 16

2 years

102. 0

. 1
4TE

Approximate time
of molt.

Stage pe-
riod.

Sex.

June

July

August

.. ..do

September

October or November . .

April

June

July

August or September . . .
October or November . .
April or May

2 days . . .

4 days . . .

5 days . . .
12 days . .
11 days a .
12. 5 days.
14 days . .
15.5 days.
21 days . .
25 days. . .
5 months.
1 £ months
33 days c.
51 days. . .

M. F.
M. F.
M. F.
M. F.
M. F.
M. F.
M. F.
M. F.
M. F.
M. F.
M. F.
M. F.
M. F.
M. F.
M. F.
M. F.

a The fifth stage period is generally shorter than the fourth.

b For female lobsters bearing eggs, there can naturally be no molt during the period that the external eggs are carried; this is
at least for n or 12 months.

c The midsummer stage period is usually the shortest.

NATURAL HISTORY OF AMERICAN LOBSTER. 363

Table 14 (after Hadley). — An Estimate op the Rate op Growth of the American Lobster
from Time of Hatching to Attainment of a Length of 22% Inches — Continued.

Stage.

Approximate

age.

Length.

Increase.

Approximate time
of molt.

Stage pe-
riod.

Sex.

Milli-

meters.

Inches.

Milli-

meters.

Inches.

Per cent.

Mn t

19. 0

M. F.

months.

141. 0

sVs

?n n

M. F.

months.

^r* tq

t6?

M. F.

180. 0

7/4

M. F.

months.

onn 0

Late spring

M. F.

222. O

months.

222. O

8 7/8

?•? n

Late summer or autumn

months.

"Mo 23

„ , _ _

23 O

25. O

Late summer or autumn

months. &

273 ci

T T

27^ Cl

months.

3<~vn n

j_2

10 years 4

300. O

25. O

Autumn

months.

of,

3 7 7 n

?7 ci

12 years 4

327. 0

I31T

27. 0

Autumn

months.

T^Tr' 2 7

3 rfi n

T/\ \y/

09 n

14 years 4

356- 0

1414

29. O

Autumn

months.

?4 ci

16 years 4

380. 0

isK

24. 0

Autumn

months.

/\nf\ n

of\ 0

18 years 4

406. O

26. 0

Autumn

months.

>13 T n

T7X/i

75 Cl

20 years 4

43I. O

25. 0

Autumn

months.

I8r4

on ^

A, n

OC\X/

21 4

or n

568. O

or 0

a After the eighteenth stage it is very doubtful whether the lobster molts oftener than twice in a year.

& 1 1 is uncertain at just what time the spring or early summer molt for female lobsters not bearing external eggs is first omitted,
but it is probably near this stage.

It is shown, however, by Hadley, that the rate of growth is more rapid in the young
Wickford lobsters (stages 1 to 17), that it begins to fall at the age of about 2x/2 years
(stage x 8) , becomes differentiated in the sexes in favor of the more rapid growth of the
male at the twenty-third stage, and continues to decrease, the stage period becoming
longer and longer with age, especially in the female, where the production of eggs pro-
ceeds at a very rapid rate. Thus, according to Hadley, the increase in the 12-inch lob-
ster has dropped to 9 per cent, or about one-half that in the first 17 stages, and while both
sexes have molted 25 times, the male is but 7 years old, while the female is 10 years and
4 months. Thus he thinks that the female is outstripped in the race with the other sex
on account of the drain upon her vitality due to the periodic production of a rapidly
increasing egg supply, and that this accounts for the fact that so far as observed giant
lobsters beyond 18 or 20 inches in length are invariably of the male sex.

364

BULLETIN op the bureau of FISHERIES.

Following Hadley’s estimate still further, for the larger lobsters, upon the age or
rate of growth of which no data are yet available, a male lobster 19^2 inches long is 20
years old and has passed successfully 32 molts, while a mammoth measuring 22% inches
from beak to telson has entered upon his thirty-sixth stage, and attained to the green
old age, for a lobster, of 33 years. According to my earlier estimate a lobster at the
thirtieth molt had attained a length of 19.1 inches.

That the stage periods increase with age no one can deny, for this is only another
way of saying that youth is the period of most active growth. There is no theoretical
limit to the growth of such a crustacean, although there is a practical limit. Thus lob-
sters do not attain a weight of 100 pounds, but they have tipped the scales at 34 pounds.
Again, there is no a priori reason for assuming that the percentage increase in weight in
the adult lobster at each molt may not be fairly uniform up to the period of decline. But
since molting is not only the prelude to expansion in size, but also of the greatest use to
the animal in freeing it from troublesome parasites and messmates and at the same time
keeping its cuticular glandular system in order, as well as in the repair of injuries through
the restoration of appendages and other lost parts, we should surely expect to find so
useful and necessary a process limited only by the duration of life itself. This is appar-
ently the case, and since the tendency, in all the higher organisms, at least, is to lose
vitality with age we might expect the percentage of increase in weight or in the expan-
sion of the body to decrease gradually in old age until it was practically nil, or reduced to
the ability of renewing the shell or exoskeleton only. This would seem to be actually
the case, although we have no direct observations upon which to found the opinion, and
it is possible that death from old age in the lobster, if it come at all, would follow from
final failure to cast the heavy armor, rusty with age, and scarred in many a conflict.

As has already been noticed in considering the rate of growth of the ovary (p. 299)
the volume of any part or of the body as a whole does not increase proportionately with
the length but more nearly with the cube of the length. In other words the percentage
increase in the length of the body at each molt does not accurately express the true rate
of growth, which concerns the entire volume of the body. Therefore it may be found
that after a period is reached corresponding to the length of from 8 to 10 inches, the
lobster, and more particularly the male, may increase more rapidly in volume and become
stockier, especially to be noticed in the enlargement of the big claws, while increase in
total length of the body may be relatively less.

I have shown that the male, length for length, weighs more than the female, and
that a female with external eggs is lighter than one of the same length without eggs
(149, p. 118-120, table 31); it is therefore only natural to expect to find the female
handicapped by the male after reaching sexual age to 12 inches).

We will now briefly consider the rate of growth of Woods Hole lobsters, average
increase per cent 15.3, and that of Wickford lobsters with average of 18 per cent for the
first seventeen stages, or 18.4 per cent as given in another place. Hadley in attempting
to account for this discrepancy concludes that the former figure is too low and that it
does not represent the growth of young lobsters under natural conditions at Woods Hole.

NATURAL HISTORY OF AMERICAN LOBSTER.

365

I think it highly probable now, as I did in 1892-1894, that lobsters grow more rapidly
in nature than when confined in glass jars in a hatchery, but that the measurements of
the early stages of the lobster which were then made were correct for the place and time
there can be no doubt. They were taken upon a standardized scale, and made with
care under a hand lens or dissecting microscope.

The lobster in the first stage, according to our table, was found in fifteen measured
individuals taken from the hatching jars to have an average length of 7.84 millimeters
(extremes 7.50 to 8.03 mm.), against an average length of 8.2 millimeters as given by
Hadley for Wickford, R. I. The eggs from which these young were hatched at Woods
Hole were stripped from old lobsters, taken in June to July, and placed in the McDonald
type of jar then in use. The mean average temperature of the sea water at the U. S.
Fish Commission wharf for a period of five years from 1889 to 1893 was for June 62. i° F.,
and for July 69. i° F. The water in the hatching jars was found to average one degree
higher than that outside. Since I could not begin operations until the latter part of June,
the eggs with which I had .to deal directly or indirectly had reached a late stage of devel-
opment under natural conditions, and were near the hatching point when taken. Ac-
cordingly these eggs were probably not undersized and the larvae may be regarded as
normal for Woods Hole for the period in question.

What is the average length of first-stage lobsters hatched in the waters of Vineyard
Sound? Although during six consecutive seasons (1889-1894) I never succeeded in
taking, with the net at the surface of the sea, under natural conditions, a single larva
of the first stage, and but one of the third stage, this question can be partially answered
by the earlier observations of Smith (256) made in 1871, who says that “the lobsters in
the first stage were first taken July 1 , when they were seen swimming rapidly about at the
surface of the water among great numbers of zoeae, megalops, and copepods.” * * *

“They were frequently taken at the surface in different parts of Vineyard Sound from
the 1st to the 7th of July, and several were taken off Newport, R. I., as late as
July 15, and they would very likely be found also in June, judging from the stage of
development to which the embryos had advanced early in May in Long Island Sound.
These young lobsters with two exceptions were taken at the surface in the daytime
(forenoon) from July 1 onward, but not so commonly as young in the fourth stage.”
Smith gives the measurement of the first stage as 7.8 to 8 millimeters. It therefore
seems probable that the average length of Woods Hole lobsters in the first stage is under
8 millimeters, and not above this measure as found by Hadley for the same stage at
Wickford, but probably above 7.84, the average found for the artificially hatched young.
If this be the case, it is quite certain that the rate of growth up to at least the tenth
stage is slower than at Wickford, as is further indicated by the longer stage periods.

Hadley concluded that a n-ineh male lobster from Wickford was 6 years old, while
a female of the same length was 8 years of age, whereas upon the Massachusetts coast
this length is not attained in less than 7 and 9 years, respectively. Accordingly a 10-inch
Wickford male would be about 6 years old, and a female of the same length somewhat
over 7 years. I am inclined to doubt whether the difference is really as great as is here
implied.

366

bulletin of the bureau of fisheries.

While we can not make direct comparisons with confidence without knowing the
number of individuals in each case concerned, figures which neither Smith nor Hadley
give, I am inclined to believe that while the rate of growth for Woods Hole lobsters
during their earlier stages may be greater than 15.3 it is less than 18 per cent, and that
while my former estimate of the age of a 10-inch marketable lobster to be from 4^2 to 5
years may need the addition of a plus mark, especially in the female, it is probably not
far from the truth.

Female lobsters are found bearing eggs for the first time when measuring from 7]/^
to 12 inches (18.5 to 30.5 cm.). Amid limits so wide it is impossible to say at what
time the average female lobster reaches the reproductive age, but it is probably not far
from the 10-inch length, which according to Hadley would represent the twenty-third
molt and an age of about years. We have no data upon the time of sexual maturity
in the male, but should expect that it would be reached at the same or at a slightly
earlier period.

Regarding the questions of rate of growth in Homarus gammarus of Europe, I shall
give the general conclusions of Ehrenbaum (87), whose studies at the Helgoland laboratory
are well known :

It is possibly not superfluous at the end of these observations to state again clearly that the results
which the American naturalists and we in reliance upon them have reached in regard to growth and the
relations between size, age, and life-stage cannot be regarded as completely reliable.

The numerical results which are given in the works referred to and which have been partly repro-
duced, can in the most favourable cases be regarded as of only average value, especially when we reflect
that all biological relations possess a certain variability and cannot be expressed in absolute figures.

If, moreover, we reach the result that the Helgoland lobster lays her eggs for the first time in her
seventh year of life, it by no means contradicts the idea that in many individuals this may happen
in the sixth year, while occasionally females of only 23 centimeters (g y& in.) in size have been observed
with extruded eggs, and moreover it may happen that in single cases the first egg-laying is delayed
until the eighth year of life.

But even disregarding this natural and anticipated variability, it cannot be denied that our figures,
even as averages, possess a certain untrustworthiness, since only one element rests upon direct observa-
tion, while another is based upon combinations. This uncertainty is sufficiently reflected in my earlier
contributions (see communication of 1903, p. 154), wherein I came to the conclusion that female lobsters
were in their sixth year of age when for the first time they carry eggs, while now, standing upon a basis
not much more extended, I have accepted the seventh year in preference.

Moreover the American authors waver between the sixth and seventh year as regards the period in
question, and find a wray out on the supposition that the period is six years for the southerly state of
Rhode Island, and seven years for more northerly Massachusetts and Maine. Accordingly it is well to
lay it down as a general rule that the first egg-laying takes place in the sixth or seventh year of life,
with the higher probability favoring the longer period. This statement would then hold good for both
American and European lobsters throughout their areas of distribution. Moreover, it can be accepted
as fixed that this egg-laying takes place in from the twenty-third to the twenty -fourth stage of life.

Chapter XII.— THE PRESERVATION AND PROPAGATION OF THE LOBSTER.

The lobster is easily the king of the crustacean class, and though neither “fish, flesh,
fowl, nor good red herring,” he is excellent eating, and that his race may increase is a
wish generally felt and often expressed. Unfortunately, for many years past we have
watched this race decline until some have even thought that commercial extinction,
and that not far remote, awaited the entire fishery. What is the matter with the
lobster ?

If this is primarily a scientific question, the zoological history of the animal should
give us the answer. The lobster has attracted many naturalists and other observers,
both in this country and in Europe, especially during the past 15 years, until it has
become the focus of a wide literature, as a glance at the bibliography at the close of this
work will show. Indeed, few marine animals are now so well known. The main biologi-
cal facts concerning this classical type are well in hand, and excuse can no longer be
offered on the ground of ignorance.

If the question is only an illustration of “many men, many minds,” we may as
well give it up and let the process of extermination take its usual course. However,
we consider that this problem is primarily a scientific and not a social one. When the
causes of the evil are definitely known, it becomes necessary to evoke the law. If
ideal legislation can not be secured, we must then strive for the best within reach. It
is obviously useless or even worse to enact laws which can not be enforced, and statutes
which are a dead letter and have no moral effect had better be expunged.

We have already given a brief history of this valuable fishery (p. 170), and shall
now consider in a little more detail the evidences of its decline and what we consider
the most effective remedies for its restoration.

THE FACT AND CAUSE OF DECLINE.

It is no exaggeration to say that in practically every known natural region of the
North Atlantic coast the lobster fishery is either depleted or in a state of decline. The
evidences of this condition are to be found in steadily increasing prices and in the sta-
tistics of the fisheries.

The market price, or cost to the consumer, has steadily advanced in direct ratio
to the steady decrease in the market supply. Thus, in 1889 the annual catch of lobsters
in the United States was somewhat over 30,000,000 pounds, valued at over $800,000;
in the course of a decade, or in 1899, the annual crop was reduced by one-half, while
its value had more than doubled. Since 1899 the failing supply has not been sensibly
checked. Statistics of the fisheries of the two New England States — Maine and Massa-
chusetts— which are most interested in the lobster question, have the same story to
tell. In Maine, which in some years has produced two-thirds of the entire output of

367

368

bulletin of the bureau of fisheries.

this fishery, the catch amounted to 14,234,182 pounds, with a market value of $268,739.
Twenty years later the product had fallen to 12,346,450 pounds, a decline of over
2,000,000 pounds, while its value ($1,062,206) had advanced fourfold. The product
of the fishery for 1880 in Massachusetts was 4,315,416 pounds, which sold for $158,229,
while the catch of 1900, though only half as great, was worth more than that of 10 years
before.

The average price per pound in the shell in Canada was 9.12 cents in 1883, 14.10
cents in 1893, while in 1S98 it had risen to 18.72 cents {187). Large lobsters which 25 or
30 years ago could often be bought at 5 cents apiece are now sold in the shell at 20 to
30 cents a pound,® which at the latter figure represents a cost of about 55 cents a pound
for all the edible parts, and over a dollar a pound for the clear meat of the tail and claws
alone. (See table 3, p. 214). Thus, from being one of the cheapest food products of
the ocean, this delicious crustacean has become one of the dearest luxuries. Once
the regular summer visitor to the country villages throughout the New England States,
it has now practically disappeared from the markets of all but the larger centers, and is
there to be had only at many times the former cost. The fame of the live broiled lobster
has spread over the Eastern and Western States, but, regardless of size or quality, the
consumer must pay from 60 cents to a dollar or more for a single lobster.6

The former abundance of these animals on the Atlantic coast of Canada and New
England was incredible, and probably for many years in succession more than 100,000,000
have been marketed, representing a cost to consumers at present prices of upward of
$40,000,000. The shores on certain sections of the coast have been often described
as strewn with lobsters in “windrows” after a storm. (See p. 218.) The animals
were so common it is not surprising that their value was not appreciated.

A fisherman at Southwest Harbor, Maine, who had trapped lobsters for half a
century, gave me the following account of his experience: About the year 1875, when
the annual shrinkage in the wild crop had already been felt in many places, he took
at one haul from 100 traps, which had been down 2 days, 1,985 pounds of lobsters. All
but 15 of his pots contained lobsters, and from one, which was filled to the spindle,
35 animals were taken. As a contrast to past conditions, few of marketable size were
at this time to be caught (July 27, 1902). The day before our interview this fisherman’s
son pulled 60 traps, set off Bunkers ledge, between that point and the Duck Islands,
once a famous fishing region for this crustacean, and took only 9 lobsters of marketable
size. Illustrations of this kind could be extended indefinitely, but the fact of decline
is the one subject upon which all are agreed. It is the burden of nearly every report
on the fishery which has been issued for a score of years.

The causes of the decline of the fishery are plainly evident. More lobsters have been
taken from the sea than nature has been able to replace by the slow process of reproduc-

a Thirty cents a pound at Cleveland, Ohio, April, 29, 1907. Wholesale prices at T Wharf, Boston: Targe live lobsters, 24
cents per pound; boiled, at 28 cents; chicken, live, at 18 and 20 cents; boiled, 20 and 22 cents. — (The Boston Globe, August 4,
1910.) Retail prices at the same time, 30 cents per pound; earlier in season, 2s cents.

b Lobsters are not cheap in the restaurants of London, where boiled lobsters are sold for 8 pence to 2 shillings or more each,
according to size. One and six is a common price for the half of a boiled lobster. (1903.) (Compare p. 173.)

NATURAL HISTORY OF AMERICAN LOBSTER.

369

tion and growth. In other words, man has been continually gathering in the wild crop,
but has bestowed no effective care upon the seed. The demands of a continent steadily
increasing in wealth and in population have stimulated the efforts of the dealers and
fishermen, who must work harder each year for what they receive in order to keep
up the waning supply. The natural result has followed, namely, a scarcity of numbers
and a decrease in the size of the animals caught, with steadily advancing prices paid
for the product. This is precisely what we should have been led to expect, had we
based our judgment upon any sound principles of common sense and human economy,
not to speak of a knowledge of the mode of life and general natural history of the
animal in question.

THE PROBLEM.

The problem before us is how to aid nature in restoring and maintaining an equi-
librium of numbers in the species, or how to increase the number of adult animals
raised from the eggs. It concerns not only the fisherman who earns a livelihood through
the fishery, or the dealer who has capital at stake, but the public of many lands; in
fact, everyone in the Western Hemisphere at least who likes the lobster for food. When
the decline of the already depleted fisheries became a serious menace protection was
sought in legislation, but since the lobster supply of this country is drawn from several
States and from Canada and the maritime provinces as well, no uniformity of laws
or methods was to be expected. Each state enacted its own laws, which were often
widely at variance, unscientific, and subject to continuous change. Up to the present
time every effort to check the constant and ever-increasing drain upon this fishery
has signally failed, which shows that either the laws are defective or that the means
of enforcing them are insufficient.

A sound and essentially uniform code of laws for the entire fishery is plainly
demanded if legal restrictions are to be of much avail.

HOW THE PROBLEM HAS BEEN MET.

What means have been adopted in this country and in other parts to check the
decline of this fishery so general and so universally acknowledged ? The more important
restrictive measures enacted at sundry times and in divers places have been as follows:

(1) Closed seasons of various periods in different localities.

(2) A legal gauge or length limit — namely, 9 inches in New York, Rhode Island,
and Connecticut; iojT inches in Maine, New Hampshire, and also in Massachusetts,
until reduced to 9 inches in 1907; 8 inches in Norway and England; and 8, 9, and 10 K
inches in different districts of Canada; in all cases penalizing the capture and sale of all
lobsters under these limits, and legalizing the destruction of all adults above the gauge.

(3) “Egg-lobster” laws,a or the prohibition of the destruction of female lobsters
carrying their external eggs. In addition to such legislative enactments, efforts of
a constructive character have been made as follows :

a The phrases “egg lobster," ‘‘berried lobster," or "lobster in berry," or "lobster with external eggs," are all synonymous,
and always mean a female with her cargo of eggs, new or old, attached to the swimming feet under the tail.

48299° — Bull. 29 — 11 24

3?o

BULLETIN OF THE BUREAU OF FISHERIES.

* (4) To increase the supply of lobsters in the sea by fry or larvae artificially hatched
and immediately liberated, and as practiced chiefly in Canada, by holding the berried
lobsters in large inclosures, called lobster pounds, ponds, preserves, or parks, and
later setting them free when the young are ready to hatch.

(5) By the rearing method later introduced of holding the fry artificially hatched
and rearing them until the fourth or fifth stages, when they go to the bottom and are
able to take care of themselves. We need not enter here into other legislative channels,
such as laws prohibiting the sale of broken or picked-out lobster meat, the operation
of canneries, and the construction of gear, however necessary they may be for this
fishery. We shall devote our attention mainly to those questions of most vital con-
cern to the fishery as a whole.

CLOSED SEASONS.

A closed season for any animal, during which it is made illegal to hunt or fish for
it, can only be completely justified and placed upon a scientific basis when it is made to
correspond to the breeding season of the species as a whole, and when this season is
limited to a relatively small part of the year. Neither of these things is possible in
the lobster, since the question is complicated by the fact that this animal spawns but
once in two years, so that not more than one-half of the adult females reproduce
annually, and the eggs when laid are carried about by the lobsters through nearly an
entire year. Closed seasons of this character are therefore not to be recommended,
since they serve merely to restrict the total amount of fishing done in the year, and
do not touch the root of the difficulty.

There is a closed season in the maritime provinces from June 30 to January 14,
and in 1889 the Norwegian fisheries laws prohibited the taking and sale of lobsters
from July to November. The apparent aim in these cases is to protect the lobsters
during the spawning season and for a longer or shorter period after it, but the females
only can receive much benefit, and then only provided the law against the destruction
of their eggs is observed. Closed seasons set a limit to the period of destruction and
may help to preserve the females by taking them into the protected class, after they
have emitted their eggs.

As we have already shown, the lobster is a very sedentary animal, so far as any
extended coastwise migration is concerned, and many which escape the traps in the
fall will undoubtedly enter them again in the spring and upon the very same grounds.

PROTECTION OF BERRIED LOBSTERS.

A certain percentage of lobsters captured at all times of the year bear spawn, and
how best to save these animals and their eggs is a serious question. The Maine laws
impose a fine of $10 for every berried lobster destroyed or offered for sale. It is an
easy matter to brush or comb off the eggs, however, and thus evade the law, which it
is impossible to enforce completely; but however difficult of enforcement it is not wise
to invite the destruction of the seed, upon which we depend for every future crop.

NATURAL HISTORY OP AMERICAN LOBSTER.

371

To save the precious spawn thus inevitably lost two plans have been tried or sug-
gested: (1) Collecting the egg lobsters from the canneries and fishermen and subse-
quently hatching and liberating the fry, and (2), placing the berried females thus
obtained in suitable inclosures and allowing the young to hatch under more natural
conditions. The former plan has been adopted and carried out on a rather large scale
in Canada and less extensively in the United States. As a means of saving the eggs
which might be otherwise totally lost, both methods are to be commended, but for the
preservation of the fishery neither is adequate.

By use of the second method more eggs would doubtless be hatched and more vig-
orous larvae produced, while, on the other hand, an unnatural concentration of the young
at a few points near shore would lead to a greater destruction. The hatching and imme-
diate liberation of the young, which is far less commendable, will be later discussed.

The most important things to consider first are (2) the legal length limit, and (4)
the hatching and immediate liberation of the young, because they are fundamentally
related, have been long on trial, and have entailed great expense. That they have
had a fair trial and that they have signally failed all must admit.

THE GAUGE LAW.

No doubt there are many who are ready to affirm that the present laws would be
good enough if enforced. Most people are aware that the gauge law has not been
rigidly carried out, and that the illegal sale of short lobsters has become a trade of
big proportions. I know very well that at many times of the year it is possible to buy
short lobsters (said to come from Baltimore) in the markets of Cleveland and of other
towns in the great Middle West. Nevertheless I can not share this idea. Both of these
measures were bound to fail, and would have failed whether the short lobsters were
destroyed or not.

To come back to our question, What is the matter with the lobster, or with our
means of fostering it ? We have committed a series of grave errors in dealing with
this fishery, to the chief of which, the gauge law, the others have been contributory.

First, by legalizing the capture of the large adult animals, above io^T inches in
length, we have destroyed the chief egg-producers, upon which the race in this animal,
as in every other, must depend. Second, as supporting or contributory causes, some of
us now, like others in the past, have entertained false ideas upon the biology of this
animal, especially (a) upon the value of the eggs or their rate of survival, that is, the
ratio between the eggs and the adults which come from them, and ( b ) of the true signifi-
cance to the fisheries of the breeding habits, especially in regard to the time and frequency
of spawning and the fosterage or carriage of the eggs. Our practices have been neither
logical nor consistent, for, while we have overestimated the amount of gold in the egg,
we have killed the “goose” which lays it. We have thought the eggs so valuable that
we have been to great trouble and expense in collecting and afterwards hatching them
and committing the young to the mercy of the sea, while we have legalized the destruc-
tion of the great source of the eggs themselves — the large producing adults.

372

BULLETIN OF THE BUREAU OF FISHERIES.

This fundamental error of destroying the adult lobster was first clearly pointed out
in 1902 by Dr. George W. Field, chairman of the Commissioners on Fisheries and Game
in Massachusetts, who in various reports since has ably' advocated a sounder policy,
based both on science and common sense, as will appear later in this chapter.

At first sight this question seems to be about as broad as long and suggests the
problem of how to eat your bread and butter and save enough for another meal when
the demands of hunger are strong. While we are dependent on the adult lobsters to
yield a continuous supply of eggs, and let us say we will reserve them for that purpose,
we also depend upon a continuous supply of the young to yield the adults; moreover,
the young at 6 inches long are many thousand fold more useful to the fishery than
the eggs.

In dealing with such questions comparisons are often made with the flocks or herds
of domesticated animals, and are almost certain to be misleading. The shepherd
knows his flock and its resources; every member of it is numbered and under his control,
and he is able to select the young or the old for slaughter, as his interest or that of his
flock may demand. Among wild animals the conditions are entirely changed, and
especially in those that are aquatic like the lobster, which lives at the bottom of the
sea and is seldom seen, except when caught and brought up in a trap. We can select
or reject among the captured only and have no definite knowledge of the proportion
of young to the adults, of the various sizes, or of their distribution at any given time.
If the wild flock could be brought under our knowledge and control, the comparison
sought would be of real value.

We might form a comparison, however, which would be parallel in every respect
by assuming that the animals of a domestic herd became more valuable for breeding
purposes with each added year of life. If instead of producing 1 young at each repro-
ductive period, they were to give birth to 2 in the second year, 4 in the third, 8 in the
fourth, and so on for a considerable time, would the ranchman sacrifice his old or his
young breeders for the market ?

In dealing with the problem we are reminded of the proceedings of a fisheries com-
mittee in Great Britain, quoted by Mr. Allen (2), and the answers of a stubborn witness
on the proper legal size limit of crabs: “If they do not breed till they are much larger
than 4 X inches, do you not by killing all the crabs that are under the breeding size, stop
the supply of crabs from those fish?” This fisherman thought not. “Then,” said his
questioner, “how is the supply to be kept up if you kill the crab before sufficient time
is allowed for it to spawn once?” The witness was obdurate, and answered that they
did not kill them all. “Then,” said another member, “suppose all girls are killed when
they are twelve years of age; there would be no young women or children. I think
you understand that, and if young crabs under the age at which they can spawn be
killed, it follows that there can be no crabs from them.” “But crabs,” replied the
fisherman, “breed a deal different from what girls do; crabs when they spawn, spawn
many thousand at a time.”

While it is essential to recognize that the older the female lobster the more useful
as an egg producer she becomes, we must also remember that nature kills far more of

NATURAL HISTORY OF AMERICAN LOBSTER.

373

the young than of the adults. If man’s almost unlimited power of destruction is allowed
to supplement the destructive forces of nature, will the depleted stream of young be
adequate to maintain a steady current of adults? We think that it would, since under
Dr. Field’s plan the number of breeding animals should tend to increase year by year.

Our lobster-fishery laws, which date in the main from 1873, are in principle like
those which prevail elsewhere, and taken as a whole they illustrate the force of exam-
ple and tradition, which were established long before the biology of this animal was
even approximately understood. The past literature of this crustacean bristles every-
where with these false notions, which are more or less directly and mainly responsible
for the enactment and maintenance of the present laws and practices of this fishery.

The legal length limits of 9 and 10^2 ifiches, which sanction the destruction of the
big egg-producers, but for these supporting causes would probably never have been
retained, for these causes have led to a diversion of energy in various directions, such as
the enactment of closed seasons and the practice of hatching and immediate liberation
of the fry.

The reasoning which has led to the establishment of the gauge limit has been
somewhat as follows: Lobsters come to breeding age when 9, 10, or 10 L2 inches long, and
when they spawn they spawn many thousands at a time, which is true. Therefore, by
placing the legal gauge at 9 or 10L inches we allow this animal to breed at least once
before it is sacrificed, which is also true in the main. Ten-inch lobsters lay on an
average 10,000 eggs; the lobster, being a good mother to her unhatched progeny, and
the best incubator known, will bring most of these eggs to term, and will emit to the
sea her young by the tens of thousands. What more is needed to maintain this fishery?
The answer is, Vastly more. This race needs eggs not by the tens of thousands merely,
but by the tens of billions, and it must have them or perish. Moreover, it can get
them only or mainly through the big producers, the destruction of which the present
gauge laws have legalized. If the lobster is a good “incubator,” the sea is a very poor
nursery. We have put a false value upon the egg.

Before proceeding farther in this analysis, we shall review some of the most pertinent
facts in the biology of the lobster, most of which have been fully discussed in earlier
chapters. These facts concern chiefly (a) the period of maturity of adult lobsters; ( b )
the number of eggs borne by the females, or the size of the broods; (c) the frequency of
spawning; (d) the treatment which these eggs receive, or the habits of spawning lob-
sters; (e) the habits of the fry or larvae; and (/) possibly more important than all else,
the death rate or the law of survival in the young.

(a) Lobsters do not mature at a uniform age or size, but females produce their first
broods when from 7 to 1 1 inches long, approximately, the difference between these
limits representing a period of from 4 to 5 years (age of female lobsters at these limits
about 3 and 8 years, according to Hadley). Very rarely are eggs laid before the 8-inch
stage is reached, and the majority are mature at 10 or 10% inches, when some have reared
more than one brood. Accordingly, by merely reducing the ioK-inch gauge to 9 or 8
inches we rob the animal of the very meager protection which it now enjoys.

374

bulletin of the bureau of fisheries.

( b ) The number of eggs produced increases with surprising rapidity in proportion to
the cube of the length or the total volume of the body, from the very beginning of sexual
maturity. The approximate number of eggs at 8 inches is 5,000; at 10 inches, 10,000; at
12 inches, 20,000; at 14 inches, 40,000; at 16 inches, nearly 60,000; and at 18 inches,
nearly 80,000. In the case of 532 io>2-inch berried lobsters taken from the waters of
Massachusetts, the smallest, average, and largest number of eggs borne were 5,000, 13,000,
and 36,000. The smallest number probably represents a first brood, so that the aver-
age berried lobster at this size is probably carrying eggs for the second time. The
maximum of production is reached at the 15 to 16 inch stage, when some individuals
produce nearly 100,000 eggs at one time.

The average roj^-inch berried lobster is from 5 to 7 years old; and assuming
that it has borne eggs once before, it has lived to produce 23,000 eggs. On the other
hand, an egg-bearer 16 inches in length, which according to Hadley’s estimate is nearly
18 years old, has had a succession of eight broods and has produced 210,000 eggs.
The larger animal is thus worth nine times as much as the smaller; in other words, in
the course of twelve years its value to the fishery has been increased 800 per cent.

Again, it should be noted that it is the class of small adults up to, but not including
the 9 or 10!^ -inch animals, those which produce by the fives or tens of thousands, upon
which we have relied to maintain the race, while it is the class of big lobsters, which
produce the fifty and the hundred thousands, that has been nearly wiped out.

(c) There is a definite spawning period for the majority of adults, ranging on the
coast of Massachusetts from July 15 to August 15, and averaging two weeks later in
northern Maine. A relatively small per cent lay their eggs in fall and winter.

(d) It is a fact, though frequently denied, that the American lobster lays its eggs,
as already stated, but once in two years (though rare exceptions to this rule may be
looked for), and not annually, as was formerly supposed.

(e) The eggs are carried attached to the underside of the tail, and admirably
guarded by parental instinct for nearly a year, or until they are hatched 10 or n months
after deposition.

Ignorance of the fact that there is a definite spawning period, that the eggs are laid
but once in 2 years, and that they are subsequently carried from 10 to 1 1 months, to hatch
in June or July following the summer when laid, is responsible, in considerable measure,
for erroneous ideas regarding the efficacy of closed seasons, laws protecting the berried
lobster, and other matters of legislation, the effects of which have not yet worn away.

(/) The fry or young, when hatched, rise to the surface or toward it, and lead a free-
swimming life for 3 weeks, hardly larger than a mosquito and infinitely more harmless,
translucent, brilliant in reds and blues, and quite helpless in the presence of all but the
minute animals upon which they prey. They perish quickly by the thousands before
the storm and the countless fish and other enemies which they meet in their varied
movements, and which do not disdain small fry.

At the third molt, or the fourth, counting that passed at the time of hatching, with
what seems like a sudden leap and bound, they are transformed into the fourth or the

NATURAL HISTORY OR AMERICAN LOBSTER.

375

lobsterling stage, which really looks like a little lobster. Either in this stage or in the
fifth, which follows, they go to the bottom, hide under stones, burrow in the sand, and
show an ability to protect themselves. The most critical period of infancy being now
past, one lobster at this stage is worth many thousands in the first. Therefore, our
efforts, to be of real avail, should not end with the hatching and immediate liberation
of the fry; we should rear them to the bottom-seeking stage.

THE LIFE RATE OR LAW OF SURVIVAL.

What is the death rate or the rate of survival in the lobster? Upon the answer
to this question hinges the gauge or legal-length law, as well as the expensive practice
of hatching and turning loose the young, which has been pursued in this country and
Canada for many years (since 1886 in the United States and since 1891 in Canada).

As was pointed out 10 years ago, too many fish culturists have been content to turn
out so many thousands or millions of eggs of lobsters and fish, and confidently expect
results, to the neglect of the most important question of the whole matter — the rate of
survival in the young set free, or the number of adults which can be raised from them —
the very end for which all the time, trouble, and money have been expended.

In the popular mind an egg is an egg, like that of the fowl which we eat for breakfast.
An egg really represents opportunity or chance to survive, and its biological value to the
race depends upon the law or rate of survival, which was definitely fixed in nature before
the advent of man with his traps and hatching jars, and differs in every species of
animal and plant known. When the gantlet of life is long and hazardous, especially
in infancy, nature, as in the present case, multiplies the chances or multiplies the eggs.
Many eggs always means death, under natural conditions, to all but a remnant of the host.
The number of eggs alone serves as a rough gauge to determine the rate of survival.

At one end of the scale stand the birds and mammals, with few eggs and the highest
life rate known, secured by guarding and parental instincts, with big yolks and rapid
development in one case and the special conditions of fetal life in the other. At the
other extreme we find a parasite like the tapeworm, where the conditions of early life
are so unpromising — since it must run a long hazard of chances and be eaten by two
distinct vertebrates — that its eggs are required by the hundreds of millions or even
billions. The lobster needs more eggs than the trout, and of smaller size, but far less
than the edible blue crab, which carries nearly five millions of eggs attached to its
body. Each one of these is barely visible to the unaided eye and the young which
issues from it must pass a long and dangerous larval period before reaching maturity.

What, then, is the life rate or rate of survival in the lobster? Probably not more
than 2 in 30,000, and certainly not more than 2 in 10,000. This number would be exactly
known, provided we knew the exact proportion of the sexes or the proportion of the
total number of males to the total number of females and the average number of eggs
laid by mature females during their entire life. The life rate accordingly would be
expressed by the proportion 2 :%, in which x represents the average number of eggs
laid by mature females during the whole of life.

376

BULLETIN OF THE BUREAU OF FISHERIES.

Since the sexes are about equal numerically, to maintain the species at an equi-
librium it is only necessary for each pair of adults, or for each adult female to leave two
children which attain adult age, whatever the actual length of life in either generation.
If the adult progeny exceeds two, the race will increase; if less than two, it will diminish.
Since under present conditions the race of this animal is falling off, the actual rate of
survival for the individual having remained the same, the total number of survivals
only has changed. In other words, there is at present a deficiency of eggs.

What is the average number of eggs for the entire life of this animal? We know
the minimal and maximal limits of egg production in individuals (roughly, 3,000 and
100,000); we know the average number of eggs borne at the average age of maturity
(at the 10-inch size, 10,000 eggs); but, as Allen (5) in discussing this question points
out, we do not know the number of female lobsters destroyed at different ages. Many
after laying their first eggs are killed before any young are allowed to hatch, and the
number which survive to produce successive broods is a constantly diminishing one;
but this is made good in part by the rapid increase in the number of eggs.

The average number of eggs borne by all the berried lobsters captured should give
us an indication of the average number of eggs borne by all female lobsters during life —
the number sought. In 4,645 egg lobsters from the Woods Hole region, Massachusetts,
the average number of eggs was 32,000, which would correspond to a 13 or 13^2 inch
lobster which had produced three or more broods. Allen found the number of eggs
borne by 96,098 lobsters caught in Newfoundland to be 2,247,908,000, which would give
an average of 23,000 to each female. This number corresponds to an animal 12 or 12^
inches long, which, as he remarks, from the known average age at which female lobsters
mature (10-10^ inches), would be carrying at least a second brood. Such a lobster
must therefore have produced 13,000 eggs (the average product at 10)^ inches) plus
23,000, or at least 36,000 in all. We are therefore right in concluding that the maximum
rate of survival of 2 in 10,000, formerly given, was much too high, as it was known to be
at the time, and that the proportion of 2 to 30,000 is much nearer the truth. Another
estimate, by Meek ( 200 ), based upon the statistics of the fisheries of Northumberland,
England, gives a life rate of 1 in 38,000.

If, then, it is true, as we are thoroughly convinced it is, that the normal rate of
survival in the lobster is not greater than 2 in 30,000 or 1 in 15,000 (and it can not be
greater than 2 in 10,000), the fact is big for the lobster fishery, and the sooner it is faced
the better. It has a direct bearing upon our laws and fishery operations. It enables
us to evaluate the egg and the egg lobster truly. It shows in a conclusive manner that
the present gauge laws are indefensible, because they rob the fishery of the billions of
eggs necessary to maintain it. It further shows that the method of hatching the eggs
of this animal and immediately liberating its young is ineffective, because of the meager
results which can come from it. On the other hand, it speaks loudly in favor of a law
to protect the large egg producers, and of the newer plan of rearing the young to the
bottom-seeking stage, as the only means by which pisciculture can hope to aid this
fishery materially.

NATURAL HISTORY OR AMERICAN LOBSTER.

377

The Importance of the law of survival to the operations of the fisheries, and espe-
cially in its bearing upon some of our present illogical laws, is the only excuse for dwelling
upon it at this length. To illustrate further: With respect to period of maturity and
value to the fishery, all lobsters in the sea may be divided into three classes — (i) the
young and adolescents, mainly from egg or larva, to the 8-inch stage; (2) intermediate
class of adolescents and adults, 8 or 9 to 10J2 inches in length; and (3) large adults,
mainly above 10J2 inches long. The biological value of the individual increases with
every stage from egg to adult of largest size, and therefore is greatest in class 3. The
present laws sanction the destruction of class 3, but class 1, the beginning of the series,
must, as we have seen, be mainly recruited from this class or from those animals which
under present conditions are being wiped out. In other words, our policy shifts the duty
of maintaining the race upon the small producers, which the law of survival plainly tells
us it is unable to bear. There is no way of getting over this grave defect.

We speak of the “living chain” from egg to adult, but the metaphor is not a
happy one. There i-s no “chain” relation in living nature, only a succession of indi-
viduals, of individual eggs, united in origin but discrete in each generation. The embry-
ologist begins with the egg, but the fish culturist with the egg producer. Spare the
egg producer, then, and nature will save the race. We can not wholly take the place
of nature in dealing with the eggs, but we can defeat the ends of nature by killing the
“bird” which lays them.

But, do you say, “We have the egg lobster law, and the protection of lobsters
in spawn should remedy our difficulties?” In reply we have but to recall the fact that
adults lay their eggs but once in two years, and consequently we should not expect
to find more than one-half of this class with spawn attached to the body at any given
time. This at once reduces the protection aimed at in the egg lobster law by one-half.
The other half shrinks to small proportions when we consider that there is an overlap
of four weeks in July between the climax of the periods of hatching and spawning,
when the majority of all adult female lobsters are without eggs of any kind, and also
when we further consider the ease with which a fisherman by a few strokes of the hand
can make a berried lobster eggless.

When analyzed in the light of the law of survival, the showing of the lobster hatch-
eries is not very encouraging. The hatching and immediate liberation of the fr)' has
been practiced for many years in Europe, where experiments were made in Norway
as early as 1873, as well as in Canada and the United States. The whole number of
fry hatched and liberated on the Atlantic coast for a period of ten years, according
to official returns from the hatcheries of the United States, Canada, and Newfoundland,
reached a grand total of 4,214,778,200. Detailed statistics are given in the following
table.0

o H. F. Moore, of the United States Bureau of Fisheries, to whom we are indebted for collating these statistics, says that no
definite annual records appear in the official reports of Newfoundland for 1896 and 1897. The number of fry for each of these
years is stated to be an average of the output for the seven preceding years.

373

BULLETIN OF THE BUREAU OF FISHERIES.

Table; 15.

Fiscal year.

United States.

Canada.

Newfoundland.

1893

8, 818. 000

153. 600. OOO

517-353.000

1894

78, 398, 000

160. OOO. OOO

463, 890, 000

189s

72, 253,000

168, 200. OOO

174, 840. 000

1896

97. 079, 000

100, OOO. OOO

43*5.079. 200

1897

1 15, 606, 000

90. OOO. OOO

450, 000, 000

1898

95, 234.000

85, OOO. OOO

1 71, 900, 000

Total for io years. .

794, 916, 000

I, 206. 800. OOO

2, 213, 062, 200

In addition to the number of lobster fry planted bv the United States Fish Com-
mission in 1900, there were sent to Dr. H. C. Bumpus 3,767,000 for experimental
use. In 1902 also, in addition to the plant recorded by the commission, 6,178,000
fry were used for the same purpose.

Applying the law of survival, with life rate of 2 in 30,000, which has been shown
to be a fair allowance, this number of young would yield only 280,985, while there
must have been captured on this coast in the same period nearly 1,000,000,000 lob-
sters. By applying the maximum rate of 2 in 10,000, which we are assured is far too
large, the yield would be 842,955. To have held the fishery at an equilibrium by this
means, there should have been hatched 5,000,000,000,000 young, or 1,250 times as many
as were actually liberated.

To take another example, the total output of all the Canadian lobster hatcheries
for the entire history of this fishery, 1880 to 1906, was as follows:

Bay View, Nova Scotia, 1891-1906 1, 889, 300, 000

Canso, Nova Scotia, 1905-6 79,000,000

Shemogue, New Brunswick, 1903-1906 291,000,000

Shippegan, New Brunswick, 1904-1906 220, 000, 000

Charlottetown and Dunk River, Prince Edward Island, 1S80-

1906 256,085,000

2, 735. 385. °°°

Again, allowing the too generous rate of 1 in 5,000, this product of the activity
of 24 years would yield only 547,077 lobsters, or but little over the two-hundredth
part of the numbers caught in certain years in Canada alone.

In cases of this kind it is as detrimental to overestimate the value of the egg as
to undervalue it. The eggs are true gold, although the amount which each weighs
is infinitesimal. Like drops of water and grains of sand, these eggs count for but
little singly, but in mass the inanimate particles can make the oceans and the conti-
nents, while the living germs can fill them with teeming inhabitants.

We can not work on the colossal scale of nature in dealing with egg or larva, but
we may frustrate nature by destroying the egg producers. Nature long ago provided
for the cod and hundreds of other predaceous fishes; she took into account the tides,

NATURAL HISTORY OF AMERICAN LOBSTER.

379

the storm, and the rock-ribbed coast also, by giving to this race billions of eggs each
year; but no provision was made for millions of traps working night and day at the
bottom of the sea to destroy the producers of these eggs.

THE PROPAGATION OF THE LOBSTER.

The method of rearing the young through their critical larval or pelagic period,
until they finally go to the bottom in the fourth or fifth stages, promises material aid
to this fishery. While opinions may differ upon most of the questions which have been
hitherto discussed, here is a subject upon which all should be agreed, and we believe
that the method can not be extended too far or adopted too widely. Accordingly
we shall briefly review the history of lobster rearing.

The first successful attempts at the artificial breeding of fish in America were
made upon the speckled trout by Dr. Theodatus Garlick and Prof. H. A. Ackley, of
Cleveland, Ohio, in 1853, the eggs and sperm being forcibly removed from the bodies
of the ripe animals, brought into contact, and young trout subsequently reared from
the eggs thus artificially impregnated.

No such results have ever been obtained in the Crustacea, nor is such a procedure
possible in an animal like the lobster, owing to the unyielding nature of its body, due
to a hard external skeleton. In the case of this animal we can only remove the already
naturally fertilized and developing eggs from the underside of the abdomen, to which
they are attached by the female herself at the time of egg laying, and afterwards give
them such favorable conditions that the processes of development will proceed in a
normal course to the time of hatching, as in the case of the artificial incubation of the
eggs of fowls.

Messrs. Guillon and Coste were apparently the first to rear lobsters in Europe in
considerable numbers, and an account of their experiments, which were conducted at
the laboratory of Concarneau on the coast of France, was published in 1865 by Moquin-
Tandon and Soubeiron (202).

How sanguine were these pioneers of the success of their experiments is shown by
the following extracts :

The ease with which young lobsters are reproduced and developed in the basins of Concameau is
a sure token that upon our coasts suitable places should be readily found for establishing vivaria where
one may obtain myriads of the young, but these should not be permitted to enter the sea until they are
sufficiently advanced to resist most of the causes of destruction which constantly menace them. What
we have seen since our first visit to Concameau, namely, basins literally black with little lobsters
hatched in a vivarium , and from what we know of the habits of a great number of fishes in coming in
immense numbers to stock particular regions of the coast, we may hope that it will be possible to regen-
erate the fishery on parts of our shores. By means of reservoirs we should be able to create an abundant
food supply.

It was also stated that at the island of Tudy, M. de Cresoles had designed aquaria
for preserving, hatching, and feeding lobsters and the Palinurus or langouste, some of
the compartments being shaded or otherwise adapted to the animals in different stages
of growth.

380

BULLETIN OF THE BUREAU OF FISHERIES.

The writers quoted above further add:

To surprise nature with the accomplishment, to see life develop down to the smallest details, to
possess a world of the sea in miniature in a transparent house, where nothing could escape investiga-
tion, such are really the promises of the establishment at Concameau. These promises, gentlemen,
are to-day realized.

It is pleasant to read of this enthusiasm at the dawn of the period of marine labo-
ratories, and so far as the lobster is concerned we can only regret that the difficult prob-
lems of its successful culture, which were then hardly appreciated, should have had to
wait nearly 40 years for their solution.

According to Roche (237), Mr. S. H. Ditten, a pharmacist to the court at Chris-
tiania, proposed to collect the egg-bearing lobsters in large floating cars and keep them
until the young hatched out and were set at liberty naturally.

In the years 1873 to 1875 experiments in the hatching and rearing of lobsters were
again undertaken by several gentlemen at Stavanger, Norway (227), both independ-
ently and with the aid of the Kongeligt Selskab for Norges Vel. According to the
reports of Professors Rasch and G. O. Sars they were eminently successful; many
young lobsters were carried to the ambulatory or bottom-seeking stage, the necessity
of which was duly emphasized, and incidentally important facts on the natural history
of the lobster were brought to light. Again, whatever progress was made at the time,
the work was not systematically continued.

In 1883 Saville Kent (245) contributed a paper on “The Artificial Culture of
Tobsters,” which later appeared in the proceedings of the International Fisheries Exhi-
bition at London for that year. He stated that in 1877 1,000,000 lobsters, valued at
£22,500, were imported from Norway into Great Britain; that the catch in both coun-
tries was falling off; and that the decadence of the fisheries was due to three main causes,
as follows: (1) Overfishing of the inshore districts; (2) destruction of undersized lob-
sters, and (3) destruction of the spawn for culinary purposes; the destruction of the
eggs being the chief cause, which should be combated by artificial propagation.

By feeding lobsters hatched in aquaria on minced fish he reared them to the i-inch
length, when they would go to the bottom and hide. As a result of his experience he
made the following significant remarks :

The rearing of lobsters in thousands instead of in tens or units would, it is needless to assert, be
but a matter of augmented apparatus, and what the results would be upon our depopulated lobster
grounds if several thousands, or rather millions, of such young animals could be turned out upon them
annually, those are best qualified to record a verdict who have already had practical experience in the
cultivation of the Salmonidse.

He would pay a bounty for the egg lobster in order to divert the supply of eggs,
“at present only flowing to the saucepans of the cooks,” into the hatcheries of the
cultivator, advises the use of hatching jars, feeding upon minced fish and mussels,
rearing to the ambulatory stage, and liberating on rocky ground.

Still later, in 1885, Captain Dannevig (69) also succeeded in hatching the eggs of
the lobster and in rearing the young through the first three earliest stages, at Flodevig,
Norway. He did not consider it of much service to hatch the eggs and set free the

NATURAL HISTORY OF AMERICAN LOBSTER.

381

young immediately; and he rightly said that so great was the destruction in nature
from storms and other causes that out of the 25,000 or 30,000 eggs which a lobster
might produce not a single one might reach its full development.

This work gave the first impetus to lobster culture in this country, where the hatch-
ing of eggs was accomplished in the summer of the same year (1885) at the newly opened
laboratory of the United States Fish Commission at Woods Hole, Mass., as reported by
Doctor Rathbun (229).

In 1894 we urged the importance of finding a means of rearing the young through
the free-swimming stages, and thereby reducing the terrible death rate which inevitably
occurs under natural conditions. As we then remarked, “If we could save 100 instead
of 2 out of every 10,000 hatched, every million }?oung would produce 10,000 adults and
every billion would yield 10,000,000 lobsters capable of reproduction” ( 143 ).

While results somewhat similar to those outlined above have been obtained in
England and in other parts of Europe, signal success in providing the young with a
proper food supply and in maintaining them in a healthy condition up to the lobsterling
stage has only been obtained in recent years in this country through the admirable
work of Messrs. Bumpus and Mead and their associates. These experiments were
begun under the auspices of the U. S. Fish Commission, at Woods Hole, Mass., in 1900,
and were continued at other points on the coast, and especially at Wickford, R. I.,
where, under the direction of Professor Mead and of the Commissioners of Inland Fisheries
of Rhode Island, the most efficient apparatus yet devised for the culture of lobsters has
been gradually perfected and installed. All who are interested in the problems of lob-
ster rearing should consult Professor Mead’s original papers. (See, especially, 198.)

Given a water supply which has been found by experiment to offer favorable condi-
tions for the growth of lobster larvce, and a suitable food supply, such as minced clams,
beef, or “scrambled” eggs, the apparatus mechanically aerates the water and at the same
time holds both the lobsters and their food in suspension with little detriment to the
larvae themselves.

At an early stage in his work Professor Mead found that in no case was the number
of lobsters reared to the fourth stage less than 16 per cent of the total number of fry
placed in the brood chambers (scrim bags, or wooden boxes, as now in use). The ratio
of survival may even exceed 50 per cent. In 1901 , between 9,000 and 10,000 lobsterlings
were thus reared at the Wickford station to the bottom-seeking stage; in 1908, between
300,000 and 400,000 fourth or fifth stage lobsters were reared and distributed on the
coast.

The rate of survival of the young in the early ambulatory stage is not known, but
it is probably not less than 1 in several hundred, or a fraction of 1 per cent.

Instead of striving to work on the vast scale of nature in dealing with the egg, this
is an attempt to improve upon nature by lowering the death rate in the most critical
period. Great care, however, is needed at every stage of the process, and especiallv at
the last, since the young do not seek the bottom at a uniform time.

Had it been our attempt to destroy this animal, could we have acted more effectively
than by destroying its great egg-producing class? When we attempt to rid this country

382

bulletin of the bureau of FISHERIES.

of the English or house sparrow, will it help greatly to break its eggs and destroy its
young ones, though so relatively few and with a far higher life rate than in the crustacean ?
Must we not eventually kill the producers of the eggs if we would be rid of the pest?
This is the nature of the treatment which the lobster has received. If we would preserve
this fishery, we must reverse our laws, as Doctor Field has ably pointed out, and follow
the principles and practice of breeders of domestic animals everywhere — use the
smaller and better animals for food, and keep the older, and in this case by far the most
valuable, for propagation.

RECOMMENDATIONS.

In applying the principles already discussed the following suggestions are offered :

1. Adopt a double gauge or length limit, placing in a perpetual close season or
protected class all below and all above these limits. Place the legal bar so as to embrace
the average period of sexual maturity, and thus to include what we have called the
intermediate class of adolescents, or smaller adults. These limits should be approxi-
mately 9 inches and u inches, inclusive, thus legalizing the destruction of lobsters from
9 to ii inches long only when measured alive. In this way we protect the young as
well as the larger adults, upon which we depend for a continuous supply of eggs. The
precise terms of these limits are not so vital, provided we preserve the principle of
protecting the larger adults.

2. Protect the “berried” lobster on principle, and pay a bounty for it, as is now
done, whether the law is evaded or not, and use its eggs for constructive work, or for
experimental purposes with such work in view.

3. Abolish the closed season if it still exists; let the fishing extend throughout the
year.

4. Wherever possible, adopt the plan of rearing the young to the bottom-seeking
stage before liberation, or cooperate with the United States Bureau of Fisheries or with
sister states to this end.

5. License every lobster fisherman, and adopt a standard trap or pot which shall
work automatically, so far as possible, in favor of the double gauge, the entrance rings
being of such a diameter as to exclude all lobsters above the gauge, and the slats of the
trap of such a distance apart as to permit the undersized animals to escape.

Many objections can be raised, but this plan is defensible on scientific grounds,
while the older methods are not. The best thing which can be said of it is that it would
eventually give us more eggs, and in an ever-increasing quantity — the greatest need
of this fishery, both now and in the future. Under present conditions, the supply of
eggs is yearly diminishing and at a tremendous rate.

The most striking objection to the proposed changes would be that if class 3, that
of the big producers, has been nearly exterminated, and we proceed to wipe out class 2,
the smaller adults, there will soon be no more lobsters; but this is not valid. No doubt
if this change were made, the supply of smaller lobsters would be temporarily increased
where the ioj^-inch gauge law still prevails, as was the case in Massachusetts in 1907

NATURAL HISTORY OF AMERICAN LOBSTER.

383

when the 9-inch law went into effect; and this might be followed by a temporary strin-
gency. No one can speak with positive assurance upon this subject, but the important
point to bear in mind is that under such an arrangement we would have a perpetually
protected class constantly growing and at work all the time.

Again, it may be asked, Will enough lobsters survive to enter the exempt class?
We believe that there would, and that the answer to this question is to be found in the
records of catches for every locality where lobsters are now trapped. Even in places
where the average size is small, larger lobsters occasionally appear, and in sizes showing
more than one year’s growth. Why were not all such animals weeded out the previous
year? Instead of waiting to be caught up in the end, these “escapes” would all enter
the protected growing class, to enjoy a green old age of 50 years and possibly more,
though we have no positive knowledge of the life span in this interesting race.

The trouble of a double gauge, such expense as would be needed in adjusting traps
to admit and hold lobsters of the legal size, would have to be met, but it would be well
worth while. In our opinion, the markets would not be seriously disturbed. Protect
the big egg producers and nature will preserve the race.

Without doubt there are many who would consider any legal measure involving a
double gauge impracticable because of the difficulty of carrying it out, for to be effective
it must be uniformly adopted and enforced. If the present laws are to be maintained
in principle, the following steps should be taken :

(1) Raise the legal gauge to iolA inches wherever it now stands below this limit.

(2) License every lobster fisherman, and adopt a standard trap, with slats of suf-
ficient distance apart to permit the undersized lobsters to escape.

(3) Destroy the present enormously destructive interstate commerce in short lobsters.

(4) Do not turn another larval lobster into the sea, but devote the energy expended
in lobster hatcheries to rearing these young to the bottom-seeking stage after the methods
now successfully practiced at Wickford, R. I.

BIBLIOGRAPHY OF THE LOBSTER— HOMARUS.

In the following bibliography we endeavor to give a record of the scientific litera-
ture of the lobsters ( Homarus gammarus and H. americanus), embracing their anatomy,
physiology, development, general habits, behavior, and habitat, as well as the lobster fish-
eries, and the preservation, artificial propagation, and economy of the species in general.
In order to reflect the history of our knowledge of the subject, we have endeavored to
include all papers, which were once, or are now, of any interest or value, from an early
period to the present time. While keeping, in the main, within the limits of original
research, we have given place to some minor works in which the knowledge of the day
or period was reflected more or less clearly. The statistical records of the fisheries, how-
ever, are so widely scattered, and in some respects so unsatisfactory, that we have
attempted to give only the most important references.

The voluminous literature of the related crayfishes, of the Norway lobster ( Nephrops
norvegicus), the spiny, thorny, or rock lobsters, “la langouste” of the French (Palinurus) ,
and the Spanish lobsters ( Galathea ) is not generally included in this survey, and when
referred to is noticed in the text. While we have endeavored to secure accuracy in
giving titles, a few have been necessarily taken at second hand; further, we have not
hesitated to add an occasional note, when in our opinion the use of this list to future
students could thus be enhanced.

1. Aldrovandi, Ulyssis.

Philosophi et medici Bononiensis. De mollibus, crustaceis, testaceis et zoophytis. De animali-
bus exanguibus reliquis quattuor. Liber secundus, qui est de crustatis. De astaco, cap.
iii. De leone, seu elephanto, cap. iv.

Crude figure of a lobster under name of Astacus verus; repeats Gesner’s figure of “Chela Astaei marini ex Zoo-
grapho;” also figures of Olaus Magnus of Astacus marinus devouring a man, and of a marine rhinoceros eating an
Astacus 12 feet long.

2. Allen, E. J.

Studies on the nervous systems of Crustacea. [The embryonic lobster] i, Quarterly Journal of
Microscopical Science, vol. xxxvi (n. s. ), p. 461-482; 11-m, ibid., p. 483-498, 2 pi., 1894; iv,
ibid., vol. xxxix (n. s.), p. 33-50, 1 pi. 1897. London.

Protection of crabs and lobsters. Journal Marine Biological Association of the United Kingdom,
vol. iv (n. s.), p. 182-187. 1:895— 97 . Plymouth.

4 •

The reproduction of the lobster. Ibid., vol. iv (n. s.), p. 60-69. 1895-97. Plymouth.

5. Anderton, T.

The lobster ( Homarus vulgaris). Report of the Marine Department of New Zealand for 1908-1909,
p. 17-23, pi. i-iv. Wellington, 1909.

Cites cases of annual breeding in European lobster transplanted to New Zealand, and describes sexual union
as following molting in the female.

384

NATURAL HISTORY OP AMERICAN LOBSTER.

385

6. Appellor, A.

Mittheilungen aus der Lebensweise des Hummers. Mittlieilungen des Deutschen Seefischerei-
Vereins, bd. 15, p. 99. Berlin, 1899.

Apparently demonstrates by experiment that at Stavanger, Norway, the European lobster spawned but once in
two years.

7 •

Indberetning til Stavanger filial av Selskabet for de norske Fiskeriers Fremme om hummerunder-
sokelser i 1892. (1) Aarsberetning for Selskabet for de norske Fiskeriers Fremme. Bergen, 1892.

Researches on the development of the lobster, 1893-1901 (2-7). Ibid., 1893-1901.

9 ■

Researches on the development of the lobster, 1902. Ibid. Norsk Fiskeritidende, bd. 22, p.
114-132. Bergen, 1903.

10.

Researches on the development of the lobster in 1903. Ibid. Norsk Fiskeritidende, bd. 23, p.
112-119. Bergen, 1904.

11. Atwater, W. O.

The chemical composition and nutritive values of food fishes and aquatic invertebrates. Report
U. S. Commission of Fish and Fisheries for 1880, p. 679-868, pi. lxxvi-lxxxix. Washington,
1892.

12. Atwood, N. E.

On the habits and geographical distribution of the common lobster. Proceedings Boston Society
Natural History, vol. x, p. n-12. Boston, 1866. See also Proceedings Essex Institute, vol.
iv, p. clxxviii-clxxx. Salem, 1864-1865.

13. Audubon, John James.

Labrador Journal; from “Audubon and His Journals,” by Maria R. Audubon, edited with the
assistance of Elliott Coues, vol. 11, p. 363.

Audubon refers to the lobster as “very scarce" in Labrador, and describes method of Indians in roasting them

alive.

14. Bancel, C., and Husson, C.

Sur la phosphorescence de la viande de homard. Comptes rendus de l’Academie des Sciences,
t. 88, p. 191-192. Paris, 1879.

13. Barnes, Earnest A.

Lobster culture in 1905. Thirty-sixth Annual Report of the Commissioners of Inland Fisheries of
Rhode Island, for 1906, p. m-119. Providence, 1906.

16.

Methods of protecting and propagating the lobster, with a brief outline of its natural history. Ibid.,
p. 120-152, 13 pi. Providence, 1906.

16 a.

Lobster culture at Wickford, R. I., in 1906. Thirty-seventh Annual Report of the Commissioners
of Inland Fisheries of Rhode Island for 1907, p. 88-98. Providence, 1907.

17. Baster, J.

Opuscula subseciva. De astacis, tom. H, lib. 1, tab. 1. Harlemi, 1762.

Figures egg-bearing lobster, and describes breeding habits of European lobster on testimony of “Norwegian
friends.”

18. Bate, C. Spence.

Fourth report on the fauna of South Devon. Report of British Association for the Advancement of
Science for 1872. London, 1873.

Observations on development of lobster.

48299° — Bull. 29 — II 25

386 bulletin of the bureau of fisheries.

ig. Bateson, William.

Materials for the study of variation treated with especial regard to discontinuity in the origin of
species, i-xvi+ 1-598 p. London, 1894.

Best review of monstrosities in appendages of lobster, chiefly the big claws, with formulation of important
principles. (Chap, xxi.)

20. Bull, Thomas.

A history of the British stalk-eyed Crustacea, i-lxvi-f- 1-386 p. London, 1853.

21. Berniiardus, Martinus a Berniz.

Chela Astaci marini monstrosa. Miscellanea curiosa medico-physica Academiae Naturae Curio-
sorum, annus secundus, observatio C, p. 174, 1 pi. 1671.

22. BiEdermann, W.

Uber den Zustand des Kalkes im Crustaceenpanzer. Biologisches Centralblatt, bd. 21, p. 343-352
(3 %•) Leipzig, 1901.

23-

Uber die Structur des Chiten bei Inseckten und Crustaceen ( Astacus und Homarus). Anatomischer
Anzeiger, bd. 21, p. 485-490. Leipzig, 1902.

24. BoEck, Axel.

Om det norske Hummerfiske og dets Historic. Tidskrift for Fiskeri, 3die Aargangs. Kjobenhavn
1868-1869. Translated in Report U. S. Commission of Fish and Fisheries, 1873-1875, p.
223-258. Washington, 1876.

25. Bohn, G.

Theorie nouvelle du phototropisme . Comptes rendus de l’Academie des sciences, t. 139, p. 890-
891. Paris, 1904.

26.

Impulsions motrices d’origine oculaire chez les Crustaces, 2 e memoire. Bulletin de l’lnstitut
psychologie, t. 5, p. 412-456. Paris, 1905.

27.

Sur le phototropisme des larves de Homard. Comptes rendus de l’Acad6mie des Sciences, t. 141,
p. 963-966. Paris, 1905.

28.

Des tropismes et des 6tats physiologiques. Comptes rendus de la Soci6t6 de Biologie, t. 59, p.
515-516. Paris, 1905.

2g.

Mouvements rotatoires chez les larves de Crustacds. Comptes rendus de la Society de Biologie,
t- 59. P- SU-S18- Paris- I9°5-

30.

L’6clairement des yeux et les mouvements rotatoires. Comptes rendus de la Soci6te de Biologie,
t- 59’ P- 564~566- Paris’ I9°5-

31. Botazzi, Fil.

Untersuchungen fiber das viscerale Nervensystem der decapoden Crustaceen. (11) Zeitschrift fiir
Biologie, n. f., bd. xxv, p. 340-371. Miinchen und Berlin, 1902.

Refers chiefly to the spiny lobster, Palinurus.

32. Bouchard-ChanterEaux.

Catalogue des Crustac4s du observes dans le Boulonnais. 1833.

33. Brandes, G.

Zur Begattung der Dekapoden. Biologisches Centralblatt, bd. 17, p. 346-350. Leipzig, 1897.

34. Braun, Max.

Zur Kenntniss des Vorkommens der Speichel- und Kittdriisen bei den Decapoden. Arbeiten aus
dem zoologisch-zootomischen Institut in Wurzburg, bd. in, p. 472-479, taf. 21. 1876-77.

NATURAL HISTORY OF AMERICAN LOBSTER.

387

35. Brightwell, T.

Description of the young of the common lobster, with observations relative to the questions of the
occurrence and non-occurrence of transformations in crustaceous animals. Loudon’s Magazine
Natural History, 1st ser., vol. viii, p. 482-486. London, 1835.

First notice of double monsters in larva of European lobster.

36. Brocchi, P.

Recherches sur les organes genitaux males des Crustaees decapodes. Reprinted from Annales
des Sciences Naturelles, 6e s6r., p. 1-132, pi. 13-19. Paris, 1875.

Figures spermatophores and copulatory appendages of male lobster.

37. Brook, George.

Notes on the reproduction of lost parts in the lobster ( Homarus ■vulgaris). Proceedings Royal
Physical Society of Edinburgh, p. 3 70-385, fig. 1-5. Edinburgh, 1887.

38. BruES, C. T.

The internal factors of regeneration in Alpheus. Biological Bulletin, vol. vi, p. 319-320. 1904.

39. Buckland, Frank; Walpole, Spencer, et al.

Reports on the crab and lobster fisheries of England and Wales, of Scotland and Ireland, p. i-xxii,
i-xxvi, i-iv and 1-80, with appendices, 8 pi. London, 1877.

40. Buckland, Frank.

Reports on the fisheries of Norfolk, especially crabs, lobsters, herrings, and broads. Presented by
Her Majesty’s command. Ordered by the House of Commons to be printed. London, 1875.

41. Bumpus, Hermon Carey.

The embryology of the American lobster. Journal of Morphology, vol. v, p. 215-262, pi. xiv-xix.
1891.

The first circumstantial account of the embryology of the lobster based upon modern methods. Describes
structure and function of seminal receptacle.

The American Lobster. Review, Science (n. s.), vol. iv, p. 536-537. New York, 1896.

Describes rayed sperm cells of lobster in “active movement.”

43-

On the movements of certain lobsters liberated at Woods Hole during the summer of 1898. Bulle-
tin U. S. Fish Commission, vol. xix (1899), p. 225-230. Washington, 1901.

44.

The results attending the experiments in lobster culture made by the United States Commission
of Fish and Fisheries. Science, n. s., vol. 14, p. 1013-1015. 1901.

43. Calman, W. T.

On a lobster with symmetrical claws. Proceedings Zoological Society of London, June 19, 1906,
p. 633-634, 1 fig. London.

46. Cano, G.

Morfologia dell’ apparecchio sessuale femminile, glandole del cemento e fecondazione nei crostacei
decapodi. Mittheilungen der Zoologischen Station Neapel, bd. ix, p. 503-532, taf. 17. 1891.

47. Carey, C. B.

Large lobster ( Homarus vulgaris). Zoologist, 2d ser., vol. 8, p. 3654. London, 1873.

Record of lobster weighing 12 pounds.

48. Carrington, John T., and Lovett, Edward.

Notes and observations on British stalk-eyed Crustacea. Zoologist, 3d ser., vol. vi, p. 9-15 (con-
tinued). London, 1882.

4Q. Cavolini.

Memoria sulla generazione dei pesci e dei granchi. Napoli, 1787. See also tiber die Erzeugung
der Fische und Krebse. Aus dem italienischen iibersetzt von Zimmerman. Berlin, 1792.

388

BULLETIN OF THE BUREAU OF FISHERIES.

50. Chadwick, H. C.

Experiments in lobster rearing. Report for 1904 in the Lancashire Sea-Fisheries Laboratory at
the University of Liverpool and the Sea-Fish Hatchery at Peel, p. 124-128, fig. 1-6. Liverpool,
1905. Also Proceedings Liverpool Biological Society, vol. xix, p. 304-308, 6 fig. Liverpool,
1905.

Briefly describes and figures first five stages of H. vulgaris, but presents no new facts.

57. Clouston, T. S.

The minute anatomy and physiology of the nervous system in the lobster ( Astacus viarinus). Edin-
burgh New Philosophical Journal, vol. 17, p. 17-51, 2 pi. Edinburgh, 1863.

52. Cobb, John N.

The lobster fishery of Maine. Bulletin U. S. Fish Commission, vol. xix, p. 241-266, pi. 28-32.
Washington, 1901.

52a. Cols, Leon J.

Description of an abnormal lobster cheliped. Biological Bulletin, vol. xviii, p. 252-268, fig.
1-9. Boston, 1910.

Describes crusher claw of Tobster, bearing a double extra claw iu secondary symmetry.

53. Collins , Joseph W.

Report upon a convention held at Boston in 1903 to secure better protection of the lobster. 1-52 p.
Boston, 1904.

54. Cornish, Thomas.

Enormous lobster. Zoologist, 2d ser., vol. 2, p. 1018. London, 1867.

55. Coste, M.

Voyage d’Exploration sur le littoral de la France et de l’ltalie. Deuxifeme edit., suivie de nouveaux
documents sur les pfeehes fluviales et marines. Publiee par ordre de S. M. l’Empereur sous les
auspices de S. Exc. le Ministre de 1’ Agriculture, du Commerce et des Travaux publiques. 4to.
Imprimerie Imperiale, p. i-xxiv, 1-298, text fig. and 2 pi. Paris, 1861. Beginning on page 157
is a series of appendices under the general title “ Documents relatifs aux Peches Marines. ” Ap-
pendix vi (p. 201-208) is entitled “ Rapport k S. E. le Ministre de la Marine sur la reproduction
des Crustaces, au point de vue de la rdglementation des Peches.”

Coste’s original account of the reproduction and development of the European lobster, thus buried in an ap-
pendix to a public document, seems to have successfully escaped bibliographers up to the present. We are indebted
to Dr. Richard Rathbun, who gave a summary of the paper in 1884 (see 226, p. S03), for unearthing it at the present
time. An indication of the accuracy of Coste’s statements is given at page 190 of the present work.

5 6-

[Report of work of Gerbe.] Faits pour servir a l’histoire de la fecondation chez les crustaces.
Comptes rendus d 1’Academie des sciences, t. 56, p. 432. Paris, 1858.

57-

Etude sur les moeurs et sur la generation d’un certain nombre d’animaux marins. Ibid., t. 47,
P- 4S-50- Paris. i858-

58. Couch, Jonathan. *

Observations on some circumstances attending the process of exuviation in shrimps and lobsters.

Magazine of Zoology and Botany, vol. 1, p. 170-173. 1837. For translation, see Bemerkungen

fiber den Hautungsprocess der Krebse und Krabben. Archiv ffir Naturgeschichte von Wieg-
mann, jalirg. 4, bd. 1, p. 337-342. Berlin, 1838.

59 •

On the process of exuviation and growth in crabs and lobsters and other British species of stalk-
eyed crustacean animals. Eleventh Annual Report of the Royal Cornwall Polytechnic Soci-
ety, 1843, p. 1-15. Falmouth, 1845.

NATURAL HISTORY OF AMERICAN LOBSTER.

389

60. Couch, R. 0.

On the metamorphoses of the decapod crustaceans. Eleventh Annual Report of the Royal Cornwall
Polytechnic Society, 1843, p. 28-43, pi- 1 • Falmouth, 1843.

61.

On the metamorphosis of the crustaceans, including the Decapoda, Entomostraca, and Pycnogon-
idae. The Twelfth Annual Report of the Royal Cornwall Polytechnic Society, p. 17-46. Fal-
mouth, 1844.

62. Coues, Elliott.

Notes on the natural history of Fort Macon, North Carolina, and vicinity (no. 2). Proceedings
Academy Natural Sciences of Philadelphia, p. 120-148. Philadelphia, 1871.

63. Cunningham, J. T.

Contributions to the knowledge of the natural history of the lobster and crab. Journal of the Royal
Institute of Cornwall, p. 1-4. Truro, 1897.

64.

Lobster rearing, Cornwall County Council Instruction Committee. Report of the Lecturer on
Fisher}'' Subjects for the years 1897-T898, 1899-1900. See also Nature, vol. lix, p. 62. London,
1898.

65- _

Experiments in hatching and rearing lobsters. Report Royal Cornwall Polytechnic Society, vol.
69, p. 25-30. Falmouth, 1901.

The author maintains that larvae of the lobster do not habitually devour living prey, but feed on carrion, like
the adults.

66. -

Reports on the experiments in oyster and lobster culture in 1902, with summary of the work from
1897. Ibid., vol. 70, p. 27-39. Falmouth, 1903.

67. Dahlgren, Ulric, and Kepner, William A.

A text-book of the principles of animal histology, i-xiv-f- 1-516 p. New York, r9o8.

Gives histological analysis of the integument, the gill filament, and other organs of the lobster.

68. Dalyell, John Graham.

The powers of the Creator displayed in the Creation. London, 1827.

69. DannEvig, G. M.

Beretning over Virksomheden ved Udklseckningsanstalten for Saltvandsfisk. Arendal, 1885. Re-
printed under title “Om Hummeravl in Dansk Fiskeritidende, ” von A. Feddersen, jahrg.
1886. See also Aarsberetning for Selskabet for de norske Fiskeriers Fremme. 1892.

70. Davies, H.

The lobster industry. 10 p. (pamphlet). Charlottetown, 1896.

Record of consultation with lobster packers of Prince Edward Island.

71. Deacon, J.

A huge lobster. The Zoologist, 2d ser., vol. 8, p. 3618. London, 1873.

72. De Kay, Jas. E.

Zoology of New York, or the New York fauna. Part vi. Crustacea, p. 23-25, pi. xn, fig. 52-53.
Albany, 1844.

73. DogiEL, J.

Anatomie du cceur des Crustaces. Comptesrendus de l’Acad6mie des sciences, t. 82, p. 1117.
Paris, r876.

De la structure et des fonctions du coeur des crustaces. Archives de Physiologie normale et
pathologique, 2e ser, t. 4, p. 400-408. Paris, 1877.

74 ■

bulletin of the bureau of FISHERIES.

390

75. Dezso, Bexa.

liber das Herz des Flusskrebses und des Hummers. Zoologischer Anzeiger, vol. i, p. 126-127.
Leipzig, 1878.

76. Dulk.

Chemische Untersuchungen eines Mageninhalts von Krebsen, die sich eben gehautet haben.
Archivfiir Anatomie und Physiologie, jg. 1834, p. 523-527. Berlin, 1834.

77 •

Chemische Untersuchungen der Krebssteine. Archiv fur Anatomie und Physiologie, jg. 1835, p.
428-430. Berlin, 1835.

78. Duvar, J. H.

Report on lobster fishery of Prince Edward Island. Annual Report of the Department of Fisheries,
Dominion of Canada. Appendix no. 6, p. 240. 1884.

79. Duvlrnoy.

Deuxieme fragment sur les organes de generation de divers animaux. Des organes exterieurs de
fecondation dans les crustaces decapodes. Comptes rendus de l’Academie des sciences, t. 31,
p. 342-348. Paris, 1850.

80. Earle, Alice; Morse:.

Home life in colonial days. New York, 1898. See p. 117 for early references to the abundance
and great size of lobsters in the Massachusetts Bay Colony.

81. Edwards, H. Milne;.

Histoire naturelle des Crustaces. 3 vol., with atlas. Paris, 1834-1840.

82.

Observations sur la structure et les fonctions de quelques zoophytes mollusques et crustaces des
c6tes de la France. Annales des sciences naturelles, 2e ser., t. 18, p. 321-350, pi. 10-15. Paris,
1842.

83. Ehrenbaum, Ernst.

Der Helgolander Hummer, ein Gegenstand deutscher Fischerei. Wissenchaftliche Meeresun-
tersuchungen, herausgegeben von der Kommission zur Untersuchung der deutschen Meere
in Kiel und der biologischen Anstalt auf Helgoland. Neue folge, bd. 1, p. 277-300. Kiel
und Leipzig, 1894.

84.

Der Hummerfang von Helgoland auf der Ausstellung in Berlin 1896, nebst Mittheilungen fiber den
Hummer. Der Hummer: Eine Zusammenstellung der Resultate neuerer Untersuchungen.
Mittheilungen des Deutschen Seefischereivereins, nr. 9, p. 12. Berlin, 1896.

*5-

Neuere Untersuchungen fiber den Hummer. Mittheilungen des Deutschen Seefischerei-Vereins,
bd. 19, p. 146-159, taf. Berlin, 1903.

86.

Ueber den Hummer (Fang, Hautung, Wachstum, Vermehrung, kfinstliche Zucht). Fischerei-
zeitung, bd. 6, p. 417-422, 433-436, 449-452, 465-477. Neudamm, 1903.

87.

Kfinstliche Zucht und Wachstum des Hummers. Mitteilungen des Deutschen Seefischerei-Vereins,
no. 6, p. 1-23, fig. 1-4 mit Beilage. Berlin, 1907. For English translation see Thirty-eighth
Annual Report of the Commissioners of Inland Fisheries of Rhode Island for 1908, p. 14-26.
Providence, 1908.

NATURAL, HISTORY OF AMERICAN LOBSTER.

391

88. Emmel, Victor E.

The regeneration of the lost parts in the lobster (Homarus americanus). Preliminary report. Thirty-
fifth Annual Report of the Commissioners of Inland Fisheries of Rhode Island, p. 81-117,
pi. xxi, xxii. Providence, 1905.

The relation of regeneration to the molting process in the lobster. Thirty-sixth Annual Report of
the Commissioners of Inland Fisheries of Rhode Island, p. 258-313, 2 pi. with charts. Provi-
dence, 1906.
go.

Torsion and other transitional phenomena in the regeneration of the cheliped of the lobster ( Homarus
americanus). Journal of Experimental Zoology, vol. in, no. 4, p. 603-620, pi. 1-2. Baltimore,
1906.

The regeneration of the “crusher-claws” following the amputation of the normal asymmetrical
chelae of the lobster {Homarus americanus). Archiv fur Entwicklungsmechanik der Organis-
men, bd. xxii, hft. 4, p. 542-552, taf. xv. Leipzig, 1906.

92.

Regenerated and abnormal appendages in the lobster. Thirty-seventh Annual Report of the Com-
missioners of Inland Fisheries of Rhode Island, p. 99-152, pi. i-ix. Providence, 1907.

93 ■

Regeneration and the question of symmetry in the big claws of the lobster. Science, n. s., vol.
xxvi, p. 83-87. New York, 1907.

94 •

Note upon experiments on control of symmetry in big claws. Science, n. s., vol. xxvii, p. 779-780.
New York, 1908.

95 •

The problem of feeding in artificial lobster culture. Thirty-eighth Annual Report of the Commis-
sioners of Inland Fisheries of Rhode Island for 1908, p. 98-114. Providence, 1908.

g6.

The experimental control of asymmetry at different stages in the development of the lobster.
Journal of Experimental Zoology, vol. v, p. 471-484. Philadelphia, 1908.

97-

A study of the differentiation of tissues in the regenerating crustacean limb. American Journal of
Anatomy, vol. 10, p. 109-158, pi. i-vm. Philadelphia, 1910.

g8. Erdl, M. P.

Entwicklung des Hummereies von den ersten Veranderungen im Dotter an bis zur Reife des Embryo,
i-x, 11-40 p., 4 taf. Miinchen, 1843.

The first independent work on the embryonic development of the lobster, with hand-colored copper-plate
engravings of the egg-embryo, good for the period, but now of historical interest chiefly.

99.

Surledeveloppementdel’ceufduhomard. (Abstract.) Comptes rendusde l’Academie des sciences,
t. 17, p. 321-322. Paris, 1843.

99a. Ewart, J. C., and Fulton, T. Wemyss.

The Scottish lobster fishery. Annual Report of the Fishery Board for Scotland for 1887, p. 189-203.
Edinburgh, 1888.

100. FarrE, A.

On the organ of hearing in Crustacea. Philosophical Transactions, p. 233-242, 2 pi. London, 1843.
See also Das Gehororgan des Hummers. Froriep’s Notizen, bd. 28, p. 183-184. Weimar, 1843.

392 bulletin of the bureau OF FISHERIES.

101. Fabre-Domergue et Bieitrix.

Le mecanisme de l’emission des larves chez la femelle du Homard europeen. Comptes rendus de
l’Academie des sciences, vol. 136, p. 1408-1409. Paris, 1903.

102. Faxon, Walter.

On some crustacean deformities. Bulletin Museum of Comparative Zoology at Harvard College, vol.
vni, no. 13, p. 257-274, pi. 1— 11. Cambridge, 1881.

103.

Selections from the embryological monographs, compiled by Alexander Agassiz, Walter Faxon, and
E. L. Mark. I. Crustacea. Memoirs Museum of Comparative Zoology, vol. ix, no. 1, pi.
1-14, with descriptions. Drawings of lobster given in fig. n-17, pi. xn. Cambridge, 1882.

104. Field, Geo. W.

A report upon the scientific basis of the lobster industry, the apparent causes of its decline, and sug-
gestions for improving the lobster laws. Report of the Commissioners of Inland Fisheries and
Game of Massachusetts for 1901, p. m-130. Boston, 1902.

Advocates a policy of protecting the older lobsters, by prohibiting the capture and sale of adult animals over ic
inches long.

205.

The biological basisof legislation governing the lobster industry. Science, n. s., vol. xv, p. 612-616.
New York, 1902.

106. ■ —

The lobster fisheries and the cause of their decline. From the 40th Annual Report of the Commission-
ers of Fisheries and Game of Massachusetts, p. 1-46, 2 pi. Boston, 1906.

207.

Lobsters and the lobster problem in Massachusetts. With discussion . Proceedingsof the Fourth Inter-
national Fishery Congress. Bulletin of the Bureau of Fisheries, vol. xxvtii, 1908, p. 211-217.
Washington, 1910.

108. Foettinger, Alexandre.

Recherches sur 1 ’organisation de Histriobdella homari, P.-J. Van Beneden, rapportee aux Archi-
annelides. Archives de Biologie, t. v, p. 435-516, pi. xxv-xxix. Paris, 1884. See also Van
Beneden, Bulletin de l’Academie royale de Belgique, t. xx, p. 63, 1853; also later account,
with plates, in memoirs of the same academy, t. xxxiv. Bruxelles, 1858.

log. Fraiche, Fexix.

Guide pratique de 1 'ostrticultour et precedes d ’elevage et de multiplication des races marines co-
mestibles. Translated by H. J. Rice, in Report of the Commissioner of Fish and Fisheries
for 1880, p. 753-824. Washington, 1883.

no. Fredericq, L6on.

Note sur le sang du Homard. Bulletin de l’Academie royale de Belgique, 2e ser., t. xlvii, p.
409-413. Bruxelles, 1879.

hi. Fredericq, L6on, and Vandevelde, G.

Vitesse de transmission de 1 'excitation motrice dans les nerfs du Homard. Archives de Zoologie
experimentale et g£nerale, t. 8, p. 513-520. Paris. 1879-80.

112.

Physiologie des muscles et des nerfs du Homard. Bulletin de l’Academie royale de Belgique. 2e s£r.,
t. 47, p. 771-779, with fig. Bruxelles, 1879. See also Archives de Biologie, t. 1, p. 1-24. Paris,
1880.

11 3. Fullarton, J. H.

The European lobster; breeding and development. Fourteenth Annual Report of the Fishery
Board for Scotland, p. 186-222, pi. vi-vm. Glasgow, 1896.

NATURAL HISTORY OF AMERICAN LOBSTER.

393

114. Garman, S.

Report on the Lobster. Report of the Massachusetts Commission Inland Fisheries and Game
for 1891, p. 60-61. Boston, 1892.

IT5-

Lobster reproduction. Zoologischer Anzeiger, xvm. jahrg., p. 38-40. Leipzig, 1895.

116. Geoffroy etc jeune.

Observations sur les ecrevisses de riviere [dated August 23, 1709]. Histoire de l’Academie royale
des sciences, 1709, p. 309-314. Paris, 1711.

The first notice of gastroliths in the lobster.

IlJ. GERBE, Z.

Appareils vasculaire et nerveux des larves des crustaces marins. Comptes rendus de 1 ’Academie des
sciences, Paris, t. lxii, p. 932-937. Paris, 1866.

118. Gesner, Conrad.

Conradi Gesneri medici Tigurini Historise Animalium. De Astaco, Rondeletius. Lib. mi, qui
est de Piscium & Aquatilium animantium natura, p. 113-119. Tiguri, 1551-1558.

One of the first circumstantial accounts of the European lobster, with many curious ideas derived from an age
of superstition, also many quaint figures. The same wood-cuts, made for the first edition of Gesner’s work, were
used by Conrad Forer in his German abridgment, which appeared forty-five years later (Franckfurt, 1598).

ng. Gilson, G.

Etude comparee de laspermatogenese chez lesarthropodes. Recueil La Cellule, 1. 1 and n, fasc. 1,2,
Crustacea, p. 140-310, pi. 8-14. Louvain, 1886.

120. Goodsir, H. D. S.

A short account of the mode of reproduction of lost parts in the Crustacea. Annals and Magazine
of Natural History, vol. xm, p. 67. London, 1844. For abstract, see also: On the reproduction
of lost parts in the Crustacea. Report British Association for the Advancement of Science,
1844, p. 68. London, 1845.

1 21. Gorham, Frederic P.

Causes of death in artificially reared lobster fry. Report of the U. S. Commission of Fish and
Fisheries for 1903, p. 175-194. Washington, 1905.

122. GrobbEn, C.

Beitrage zur Ivenntniss der mannlichen Gesclilechtsorgane der Dekapoden, nebst vergleichenden
Bemerkungen fiber die der fibrigen Thoracostraken . Arbeiten aus deni Zoologischen Institut
der Universitat zu Wien und der Zoologischen Station in Triest, bd. 1, p. 1-94, taf. i-vi.
Wien, 1878.

123. Gurney, J. H.

Note on a pied lobster. The Zoologist, 2d ser., vol. 9, p. 4080. London, 1874.

124. Hadley, Philip B.

Changes in form and color in successive stages of the American lobster ( Homarus americanus) , with
drawings from life. Preliminary report. Thirty-fifth Annual Report of the Commissioners of
Inland Fisheries of Rhode Island for 1905, p. 44-80, pi. vii-xviii. Providence, 1905.

125.

Phototropism in the larval and early adolescent stages of Homarus americanus. Science, n. s., vol.
xxii, p. 675-678. New York, 1905.

126.

Regarding the rate of growth of the American lobster. Thirty-sixth Annual Report of the Commis-
sioners of Inland Fisheries of Rhode Island, p. 153-226, pi. xxvi-xxxvii and XL. Providence,
1906. See also Biological Bulletin, vol. x, p. 233-241. Boston, 1906.

394

bulletin of the bureau of fisheries.

127. Hadley, Philip B.

Observations on some influences of light upon the larval and early adolescent stages of Homarus
americanus . Preliminary report. Thirty-sixth Annual Report of the Commissioners of Inland
Fisheries of Rhode Island for 1906, p. 237-257, 2 pi. Providence, 1906.

127 a.

Continued observations on some influences of light upon the larval and early adolescent stages of
the American lobster. Thirty-seventh Annual Report of the Commissioners of Inland Fish-
eries of Rhode Island for 1907, p. 191-216. Providence, 1907.

128.

The relation of optical stimuli to rheotaxis in the American lobster, Homarus americanus . Amer-
ican Journal of Physiology, vol. xvn, p. 326-343. Boston, 1906.

129. —

Galvanotaxis in larvae of the American lobster {Homarus americanus). American Journal of Phys-
iology, vol. xix, p. 39-52. Boston, 1907.

130.

The reaction of blinded lobsters to light. American Journal of Physiology, vol. xxi, p. 180-199.
Boston, 1908.

1 31.

The behavior of the larval and adolescent stages of the American lobster ( Homarus americanus ).
Journal of Comparative Neurology and Psychology, vol. xvm, no. 3, p. 199-302, fig. 1-22.
Philadelphia, 1908.

In this paper the author brings together his previous researches, which are the most extended and valuable yet
made upon the subject.

132. Harting, Pieter.

Een slimmezeekreeft (Homarus vulgaris). Album der Natur, p. 24. Haarlem, 1878.

133. Heller, Camil.

Die Crustaceen des siidlichen Europa. Crustacea Podophthalmia, i-xii, 1-336 p., 10 taf. Wien,
1863.

134. Hasse, C. E.

Observationes de sceleto astaci fluviatilis et marini. Dissertatio, 1-38 p., 1 pi. Lipsiae, 1833.

133. Hennschen, F.

Zur Structur der Eizelle gewisser Crustaceen und Gastropoden. Anatomischer Anzeiger, bd. 24,
p. 15-29, 14 fig. Jena, 1891.

Describes pseudochromosomes in Astacus and Homarus.

136. Herbst, J. F. W.

Versuch einer Naturgeschichte der Krabben und Krebse, nebst einer systematischen Beschreibung
ihrer verschiedenen Arten. 3 bde. Berlin und Stralsund, 1790-1804.

For an account of the lobster Cancer ( Astacus ) gammarus and the lobster fishery in Europe in the eighteenth
century, see vol. u, p. 42. A curious epitome of the lore and natural history of the higher Crustacea from the most
ancient times.

137. Herdman, W. A.

Lobster hatching. Nature, vol. lxx, p. 296. London, 1904.

Note on hatching of lobsters at Biological Station, Port Erin, Isle of Man.

138. Hermann, G.

Notes sur la structure et le developpement des sperm atozoides chez les Decapodes. Bulletin scien-
tifique de la France et de la Belgique, t. xxii. Paris, 1890.

First record of amoeboid movements in sperm cells, with description of hermaphrodite character of sexual
organs.

NATURAL HISTORY OF AMERICAN LOBSTER.

395

7jp. Herrick, Francis H.

The development of the American lobster, Homarus americanus . Johns Hopkins University Cir-
culars, vol. ix, no. 80, p. 67-68. Baltimore, 1890. See also Zoologischer Anzeiger, 1891, p.
i33-!37> and P- I4S-I49» I"6-

140.

Notes on the habits and larval stages of the American lobster. Johns Hopkins University Circu-
lars, vol. x, p. 97-98. Baltimore, 1891.

1 41.

The reproductive organs and early stages of development of the American lobster. Johns Hopkins
University Circulars, vol. x, p. 98-101. Baltimore, 1891.

142.

Cement glands and origin of egg-membranes in the lobster. Johns Hopkins University Circulars,
vol. xn, p. 103. Baltimore, 1893.

*43-

The habits and development of the lobster and their bearing upon its artificial propagation. Paper
presented at the World’s Fisheries Congress, Chicago, 1893. Bulletin U. S. Fish Commission
for 1893, p. 75-86. Washington, 1894.

144.

The reproduction of the lobster. Zoologischer Anzeiger, p. 289-292. Leipzig, 1894. See also The
Zoologist, vol. 18, p. 413-41 7. London, 1894. v

145.

The lobster. Johnson’s Universal Encyclopedia, vol. v, p. 317-318. New York, 1894.

146.

Notes on the biology of the lobster. Science, n. s., vol. 1, p. 263-266. See also Science, n. s.,
vol. 1, p. 382. New York, 1895.

147.

The reproduction of the lobster. Zoologischer Anzeiger, p. 226-228. Leipzig, 1895.

148.

Movements of the nucleolus through the action of gravity. Anatomischer Anzeiger, bd. x, p. 337—
340, fig. 1-4. Jena, 1895.

149.

The American lobster: A study of its habits and development. Bulletin U. S. Fish Commission,
vol. xv, 1895, p. 1-252, pi. A to J and 1-54. Washington, 1896.

150.

The protection of the lobster fishery. Bulletin U. S. Fish Commission vol. xvn, 1897, p. 217-224.
Washington, 1896.

-TJU

The “great forceps” of the American lobster. Science, n. s., vol. xxi, p. 375-376. New York,
1905.

152.

The reproductive period of the lobster. Bulletin U. S. Fish Commission, vol. xxi, 1901, p. 161-166,
fig. 1-5. Washington, 1902.

153 •

Torsion of the crustacean limb. Biological Bulletin, vol. ix, p. 130-137, fig. 1-5. Boston, 1905.
See also Science, n. s., vol. xxi, p. 376. New York, 1905.

154 • —

Effective protection for the lobster fishery. Science, n. s., vol. xxm, no. 591, p. 650-655. New
York, 1906.

396 BULLETIN of the bureau of fisheries.

J55. Herrick, Francis H.

Symmetry in big claws of the lobster. Science, n. s., vol. xxv, p. 275-277. New York, 1907.

156.

The preservation and propagation of the lobster. Proceedings of the First New England Conference
called by the Governors of the New England States, November 23-24, 1908, p. 41-60, with
discussion by delegates. Published for the Governors. Boston, 1908. Reprinted in Report
of the Commissioners on Fisheries and Game of Massachusetts for 1908. Public Document
no. 25, p. 29-46. Boston, 1909.

This paper has been reproduced in part in chapter xii of the present work.

157 ■

Facts about the “lobster pearl.” American Naturalist, vol. xuv, p. 294-301, fig. 1-5. New York,
1910.

158. Home, C.

Note on the phosphorescence of the lobster after death. Zoologist, 2dser., vol. 4, p. 1725-1726.

1869.

759. Hornaday, William T.

A large lobster. Zoological Society Bulletin, no. 29, p. 425-426. New York, 1908.

Records the capture of a living male lobster January 23, 1908, at Cranberry Isles, Hancock County, Me., meas-
uring 16 inches and weighing i^A pounds.

160. Hovey, E. O.

Measurements of two large lobsters recently added to the collections of the American Museum of
Natural History. Proceedings American Association for the Advancement of Science for 1898,
p. 365-366. New York, 1899.

For measurements given at reading of this communication, but not printed here, see 278.

161. HujsiT, Bookman, and Tierney.

Einige allgemeine Eigenschaften des Herzmuskels vom amerikanischen Hummer ( Homarus ameri-
canus). Centralblatt fur Physiologie, bd. n, p. 274-278, 7 fig. Leipzig, 1898.

162. Huxley, T. H.

On the classification and the distribution of the crayfishes. Proceedings of the Zoological Society,
p. 752-788. London, 1878.

For branchial formula of Homarus, see p. 777.

163. Hyatt, Alpheus.

Moulting of the lobster, Homarus Americanus . Proceedings Boston Society Natural History, vol.
xxi, p. 83-90, 1880-1882. Boston, 1883. <

164.

[Remarks on distortions of lobster’s claws.] Proceedings Boston Society Natural History, vol. xxi,
Report of general meeting, p. 278. Boston, 1883.

165. Irvine and Woodhead.

Secretion of carbonate of lime by animals. Part n. Proceedings Royal Society Edinburgh, vol.
16, for 1888-1889, p. 324-354. Edinburgh, 1889.

166. Jordan, H.

(2) Zur Frage nach der excretiven Function der Mitteldarmriise (Leber) bei Astacus fluviatilis.
Archiv fiir die gesammte Physiologie, 105. bd., p. 365-379. Bonn, 1904.

167.

(3) Zur physiologischen Morphologie der Verdauung bei zwei Evertebraten. Biologisches Ce.itral-
blatt, bd. 24, p. 321-332, 5 fig. Erlangen, 1904.

NATURAL HISTORY OF AMERICAN LOBSTER.

397

168. Jordan, H.

(4) Beitrage zur vergleichenden Physiologie der Verdauung. IV. Die Verdauung und der Ver-
dauungsapparat des Flusskrebses (Astacus fluviatilis). Archiv ftir die gesammte Physiologie,
bd. 101, p. 263-310, fig. 1-6 and taf. vn. Bonn, 1904.

Treats of physiology of digestion in lobster, and attributes both digesting and absorbing function to the midgut
or liver.

i6g. Kalm, Peter.

Travels into North America; containing its natural history and a circumstantial account of its plan-
tations and agriculture in general, with the civil, ecclesiastical, and commercial state of the
country, the manners of the inhabitants, and several curious and important remarks on various
subjects. Translated by John Reinhold Forster. 3 vol. Warrington, 1770.

Curious reference to stocking of waters near New York with lobsters by wreck of “well boat,” vol. i, p. 240-241.

170. Kolliker, Albert.

Beitrage zur Kenntniss der Geschlechtsverhaltnisse und der Samenfliissigkeit wirbeljgser Thiere,
nebst einem Versuch liber das Wesen und die Bedeutung der sogenannten Samenthiere. Ber-
lin, 1841. See also Observations pour servir h l’histoire des organes sexuels et du liquide
seminal des Crustaces et des Cirrhipfedes. Annales des Sciences Naturelles, 2e ser., t. 19,
P- 335-35°. P1- 9~z3- Paris, 1841-

171. Koltzoff, Nicholas.

Untersuchungen liber Spermien und Spermiogenese bei Decapoden. Vorlaufige Mittheilung.
Anatomischer Anzeiger, bd. 24, p. 83-95, Jena- I9°3-

172. Koltzoff, N. K.

Studien iiber die Gestalt der Zelle. 1. Untersuchungen iiber die Spermien der Decapoden, als
Einleitung in das Problem der Zellengestalt. . Archiv fur Mikroskopische Anatomie und
Entwicklungsgeschichte, bd. 67, p. 364-572, taf. xxv-xxix, fig. 1-36. Bonn, 1906.

The most complete account of the structure and movements of crustacean sperm cells, and their probable
behavior in fertilization.

173. Kroyer, Henrik.

Monografisk Fremstilling af Slaegten Hippolyte’s nordiske Arter. Med Bidrag til Dekapodernes
Udviklingshistorie. Det Kongelige Danske Videnskabernes Selskabs naturvidenskabelige og
mathematiske Afhandlinger. Niende deel, pi. i-vi, p. 133-144. Kjobenhavn, 1842.

Erdl (pS), writing in 1843, thus characterizes this work: “Gives figures and descriptions of form of the outer
parts of the lobster-embryos, especially the palps and legs. The text is brief, and the figures leave much to be
desired.’’

174. LabbE, Alphonse.

Sur la spermatogenese des crustaces decapodes. Comptes rendus de l’Academie des Sciences,
t. 137, p. 272-274. Paris, 1903.

175- •

La maturation des spermatoides et la constitution des spermatozoides chez les crustaces deca-
podes. Archives de Zoologie, ser. iv, vol. 2, p. 1-14, fig. 1-27. Paris, 1903.

176. .

Sur la formation des tetrades et les divisions maturative dans la testicule du homard. Comptes
rendus de l’Academie des sciences, t. 138, p. 96-99. Paris, 1904.

177. Lataste, Fernand.

Fecondite de la femelle du homard Americain en fonction de sa taille. Actes de la Societe des
Science du Chili, t. vi, p. 106-109. Santiago, 1896.

178. LavellE.

Recherches d’anatomie microscopique sur le test des Crustaces decapodes. Annales des Sciences
naturelles, 3eser., Zoologie, t. 7, p. 352-377, pi. 7, fig. 10-12. Paris, 1847.

One of the earliest accounts of structure of shell in lobster, describing canals (of the tegumental glands) in rela-
tion to hairs, tubercles, and angles of the exoskeleton.

398 BULLETIN OF THE BUREAU OF FISHERIES.

ijq. LEmoinE, Victor.

Recherches pour servir a l’histoire des systemes nerveux, musculaire et glandulaire de l’ecrevisse.
Parts i-n. Aunales des Sciences naturelles, 5® ser., Zoologie, t. ix., p. 99-280, pi. 6-1 1, Paris,
1868. Part in, Annales des Sciences naturelles, t. x, p. 5-54, Paris, 1868.

180. Lloyd, W. A.

Exuviation of lobsters. The Field, May 25, London, 1878. Extract in The Zoologist, 3d ser.,
vol. 11, p. 225-226. London, 1878.

18 1. Loeb, Leo.

Untersuchungen iiber Blutgerinnung. 6. Mittheilung. Beitrage zur Chemie, Physiologie und
Pathologie, bd. 6, p. 260-286.* Braunschweig, 1905.

Study on coagulation of blood in Homarus and Limulus.

182. Lovett, Edward.

Abnormal color of common lobster. The Zoologist. 3d ser., vol. vm, p. 491. London, 1884.

183.

Notes and observations on British stalk-eyed Crustacea. The Zoologist, 3d ser., vol. ix, p. 100-104.
London, 1885.

184. Lucas, H.

Notice sur quelques monstruosites observees dans les crustaces appartenant aux genres Carcinus,
Lupa, Homarus et Astacus. Annales de la Soci6te entomologique de France, 2® ser., t. n, pi. r.
Paris, 1844.

185. MacMunn, C. A.

On the chromatology of the blood of some invertebrates. Quarterly Journal of Microscopical
Science, n. s., vol. xxv, p. 469-499, pi. 33, 34. London, 1885.

186.

Contributions to animal chromatology. Ibid., vol. xxx, p. 51-96, pi. 6. London, 1890.

187. Macphail, Andrew.

Discoloration in canned lobsters. Supplement 2, Twenty-ninth Annual Report of the Department
of Marine and Fisheries of Canada, p. 1-33. Ottawa, 1898.

188. Malard, A. E.

Influence de la lumiere sur la coloration des crustaces. Bulletin de la Societe Philomathique de
Paris, 8® ser., t. iv, pi. 24-30. Paris, 1892.

i8g. Marshall, C. F.

Some investigations on the physiology of the nervous system of the lobster. Studies from the
biological laboratories of Owens College, vol. 1, p. 313-323. Manchester, 1886.

igo. Martin, M. J.

Sur un specimen blanchAtre de homard. Bulletin de la Societe Philomathique de Paris, 8® ser.,
t. iv, p. 17-19. Paris, 1892.

igi. Mather, Fred.

What we know of the lobster. Bulletin U. S. Fish Commission, vol. 111, 1883, p. 281-286. Wash-
ington, 1904. See also Scientific American Supplement, Feb. 10, 1894, and The lobster, The
Aquarium, vol. 111, p. 89-92. Brooklyn, 1894.

iQ2. Mayer, Paul.

Zur Entwicklungsgeschichte der Dekapoden. Jenaische Zeitschrift-Naturwissenschaft, bd. xi,
p. 188-269, taf. xiii-xv. Jena, 1877.

zpj. Mead, A. D.

Habits and growth of young lobsters, and experiments in lobster culture. Thirty-first Annual
Report of the Commissioners of Inland Fisheries of Rhode Island for 1901, p. 61-80, pi. i-iv.
Providence, 1901.

NATURAL HISTORY OR AMERICAN LOBSTER.

399

194. Mead, A. D.

Habits and growth of young lobsters and experiments in lobster culture. Thirty -second Annual
Report of the Commissioners of Inland Fisheries of Rhode Island for 1902, p. 25-51, 7 pi.
Providence, 1902.

195. Mead, A. D. and Williams, L. W.

Habits and growth of the lobster, and experiments in lobster culture. Twenty-third Annual
Report of the Commissioners of Inland Fisheries of Rhode Island for 1903, p. 57-86, 4 fig.
Providence, 1903.

196. Mead, A. D.

Experiments in lobster culture. Thirty-fourth Annual Report of the Commissioners of Inland
Fisheries of Rhode Island for 1904, p. 74-82. 4 pi. Providence, 1904. See also the same, in

Thirty-fifth Annual Report of same, p. 33-43, pi. i-vi.

197.

The problem of lobster culture. (Contributions from the Anatomical Laboratory of Brown University,
vol. 4, no. 3.) Proceedings American Fisheries Society, p. 156-166, 3 fig. 1905.

198.

A method of lobster culture. Proceedings of the Fourth International Fishery Congress, Bulletin
of the Bureau of Fisheries, vol. xxvni, 1908, p. 219-240, pi. vii-xi. Washington, 1910. Re-
printed in Thirty-ninth Annual Report of the Commissioners of Inland Fisheries of Rhode
Island for 1909, p. 105-138, pi. 1-9. Providence, 1909.

199.

A new principle of aquiculture and transportation of live fishes. Proceedings of the Fourth Inter-
national Congress, Bulletin of the Bureau of Fisheries, vol. xxviii, 1908, p. 759-780, pi. xc-c.
Washington, 1910. Reprinted in Thirty-ninth Annual Report of Commissioners of Inland
Fisheries of Rhode Island for 1909, p. 79-100, fig. 1-23. Providence, 1909.

200. Meek, A.

The crab and lobster fisheries of Northumberland. Report of the Northumberland sea Fisheries
Committee on the Scientific Investigation for 1904, p. 21-67. Newcastle-upon-Tyne, 1904.

201. Mivart, St. George.

The lobster. Popular Science Review, vol. 7, p. 345-353. London, 1868.

202. Moquin-Tandon et Soubeiran, J. L.

Etablissements de pisciculture de Concameau et de Port-de-Bouc. Bulletin de la Societe impe-
riale zoologique d’Acclimatation, 2e ser., t. n, p. 533-545, with fig. Paris, 1865.

Gives measurements and weights from fourth to fourteenth molts of lobsters said to have been reared in the
inclosures at this station.

203. Morgan, T. H.

Notes on regeneration. Biological Bulletin, vol. vi, p. 159-172, Boston, 1904. (Note on regenera-
tion of lobster’s claws.)

204. Newton, Edwin T.

The structure of the eye of the lobster. Quarterly Journal of Microscopical Science, n. s.,vol. 13,
P- 325-343. 2 pi. London, 1873.

205. Nicholls, F.

An account of the hermaphrodite lobster presented to the Royal Society on Thursday, May 7, by
Mr. Fisher, of Newgate Market, examined and dissected pursuant to an order of the society.
Philosophical Transactions Royal Society, vol. xxxvi, 1729-1730, p. 290-294, fig. 1-4. Lon-
don, 1731. Abridgment, vol. vn, p. 421-423, pi. in, iv. 1734.

Described for first time the structure in the female lobster now known as the sperm-receptacfle.

400

BULLETIN OF THE BUREAU OF FISHERIES.

206. OWSJANNIKOW, M. P.

Sur la structure intime du systeme nerveux du Homard. Comptes rendus de l’Academie royale
des sciences, t. 52^.378-381. Paris, 1861. See also Recherches sur la structure intime du
systeme nerveux des crustaces et principalment du homard. Annales des Sciences Naturelles,
ser. 4, t. xv, p. 129-141, pi. 6-7. Paris, i86r.

207. Packard, A. S.

The history of the lobster. Review of paper by S. I. Smith. American Naturalist, vol. viii,
p. 414-417. One pi. and fig. Salem, 1874.

208.

The molting of the lobster. American Naturalist, vol. xx, p. r73. Philadelphia, 1886.

209.

The Labrador coast. New York, 1891.

210. Parker, G. H.

The histology and development of the eye in the lobster. Bulletin of the Museum of Comparative
Zoology, vol. xx, p. 1-60, pi. 1— iv. Cambridge, 1890.

211. Patterson, A. H.

Remarkable lobster claw. The Zoologist, vol. ix, p. 350-351, with fig. London, 1905.

212. Pennant, Thos.

Article on lobsters, with letters by Travis. (See ref. no. 264.) British Zoology, vol. iv, p. 8-19.
London, 1777.

21 j. Philippi, R. A.

Zoologische Bemerkungen. Wiegmann’s Archiv fur Naturgeschichte, bd. vi, p. 181-195, taf- ni-iv.
Berlin, 1840.

Treats especially of the metamorphosis of the lobster.

214. Plateau, Fejlix.

Recherches physiologiques sur le cceur des Crustaces decapodes. Archives de Biologie, t. 1,
p. 595-696, pi. xxvi-xxvn. Gand, 1880.

Gives brief account of the anatomy of the heart of the lobster, and a detailed study of its movements by the graphic
method.

215. POUCHET, G.

Note sur un muscle vibrant existant chez le homard. Comptes rendus de la Societe de Biologie,
ser. 6, t. 2, p. 358-360. Paris, 1876.

216.

Des changements de coloration sous l’influence des nerfs, Journal de l’Anatomie et de la Physiolo-
gic, p. 1-90, 113-165, 4 pi. Paris, 1876.

217. Prentiss, C. W.

Otocyst of decapod Crustacea: Its structure, development and functions. Bulletin Museum of
Comparative Zoology at Harvard College, vol. xxxvi, p. 167-252, pi. 1-10. Cambridge, 1901.

218. Prince, E. E.

Special report on the natural history of the lobster with special reference to the Canadian lobster
industry. Supplement 1 to Twenty-ninth Annual Report of the Department of Marine and
Fisheries of Canada, p. i-iv, 1-36. Ottawa, 1897.

219.

Report of the Canadian Lobster Commission for 1898. Supplement 1, to Thirty-first Annual Report
of the Department of Marine and Fisheries, p. 1-42. Ottawa, 1899. See also Addendum.

220. Przibram, Hans.

Experimentelle Studien fiber Regeneration. (1st paper.) Archiv ffir Entwickelungsmechanik
der Organismen, bd. 11, p. 321-345, taf. 11-14. Leipzig, 1901.

Describes reversal of asymmetry or compensatory hypertrophy in Alpheus, with records of experiments on
regeneration in related Macrura.

NATURAL HISTORY OF AMERICAN LOBSTER.

401

221. Przibram, Hans.

Experimentelle Studien fiber Regeneration. (2d paper, Crustacea.) Ibid., bd. xm, p. 507-527,
taf. xxi-xxii. Leipzig, 1901-02.

222. —

Beobachtungen iiber adriatische Hummer im Aquarium (und vorlafifige Mittlreilrmg uber Rege-
nerations Versuche). Ibid., bd. 25, p. 76-82, fig. 1902.

223.

Die “ Heterochelie ” bei decapoden Crustaceen. (3d paper, Crustacea.) Ibid., bd. xix, p. 181-247
taf. viii-xiii. Leipzig, 1905.

224. Rasch.

Om Forsog med kunstig Udklaekning af Hummer. “ Nordisk Tidsskrift for Fiskeri,’- ny raekke,
2 en aargang, p. 184-188. 1875. Translated in Report of the U. S. Fish Commission for 1873-74 J
and 1874-75, p. 267-269. Washington, 1876.

223. Rathbun, Mary J.

Some changes in crustacean nomenclature. Proceedings of the Biological Society of Washington,-
vol. xvii, p. 169-172. Washington 1904.

226. Rathbun, Richard.

The Fisheries and Fishery Industries of the United States. Prepared through the cooperation of
the Commissioner of Fisheries and the Superintendent of the Tenth Census by George Brown
Goode. Section I. — Natural history of the useful aquatic animals; part v, Crustaceans, Worms,
Radiates, and Sponges, p. 759-850. With one volume of plates. Washington, 1884.

227.

In same work, section v, History and methods of the fisheries, vol. 11, pt. xxi, The crab, lobster,
crayfish, rock lobster, shrimp and prawn fisheries, p. 627-810. Washington, 1887.

228.

The transplanting of lobsters to the Pacific coast of the United States. Bulletin U. S. Fish Com-
mission, vol. viii, for 1888, p. 453-472. Washington, 1890.

229. -

Notes on lobster culture. Bulletin U. S. Fish Commission, vol. vi, p. 17-32. Washington, 1886.

230. Rathke, Heinrich.

Zur Entwickelungsgeschichte der Dekapoden. Wiegmann’s Archiv fur Naturgeschichte, bd. vi,
1, p. 241-249. Berlin, 1840. Translated by W. Francis in Annals and Magazin'e of Natural
History, vol. vi, p. 263-269. London, 1841. Abstract of complete paper which follows ( 231 ).

Describes hatching of ripe embryos of Astacus marinus ( Homarus ) and other decapods.

231.

Beitrage zur vergleichenden Anatomie und Physiologie. Reisebemerkungen aus Skandinavien.
Neueste Schriften der naturforschenden Gesellschaft in Danzig, bd. in, pt. 11, Zur Entwicke-
lungsgeschichte der Dekapoden, (1) Astacus marinus, p. 23-29, taf. 11, fig. 11-21. 1842. Danzig.

Contains a description of the hatching of the lobster, with good figures.

232 •

De Animalium Crustaceorum Generatione. Commentatio. 26 p. Regiomontii, 1844.

233. Raveret- Watted.

L’aquiculture marine en Norv^ge. Revue des Sciences naturelles appliquees, t. 37, p. 147-156,
246-257. Paris, 1890.

An account of Captain Dannevig's experiments in rearing lobsters and fish.

234. REaumur.

Sur les diverses reproductions qui se font dans les ecrevisses, les omars, les crabes, etc., et entre
autres sur celles de leurs jambes et de leurs ecailles. Memoires de l’Academie royale des
Sciences, p. 226-245, pi- 12. Paris, 1712.

48299° — Bull. 29 — 11 26

402

BULLETIN OF THE BUREAU OF FISHERIES.

235. Reed, Margaret.

The regeneration of the first leg of the crayfish. Archiv fur Entwickelungsmechanik der Organis-
men, bd. 18, p. 307-316, 3 fig. Leipzig, 1904.

236. Ridegood, W. G.

Abnormal oviducts in the lobster. Annals of Natural History, vol. in, p. 1-7, fig. 1-2. London,
1909.

237. Roch£, Georges.

La culture des mers en Europe. 328 p., illustrated. Bibliothfeque Scientifique Internationale.
Paris, 1898.

In chapter vi is given a general summary of the development and artificial propagation of the lobster and
langouste, or Palinurus.

238. Ryder, J. A.

The metamorphosis of the American lobster, Homarus americanus H. Milne-Edwards. American
Naturalist, vol. xx, p. 739-742. Philadelphia, 1886.

239-

Hatching, rearing, and transplanting lobsters. Science, vol. vii, p. 517-519. New York, 1886.

240. Sabatier, Armand.

De la spermatogenebse chez les crustaces decapodes. Travaux de l’lnstitut de Zoologie de Mont,
pellier et de la Station Maritime de Cette. 394 p., 10 pi. Montpellier et Paris, 1893.

241. Saetsr, S. J. A.

On the molting of the common lobster ( Homarus vulgaris) and the shore crab ( Carcinus mamas).
Journal Linnean Society, London, vol. 4, p. 30-35. London, i860.

242. Sars, G. O.

Om Hummerens postembryonale Udvikling. Med 2 autographiske Plancher. Christiania Viden-
skabs-Selskabs Forhandlingar, p. 1-28. Christiania, 1874.

Gives first detailed and adequately illustrated account of metamorphosis of Homarus gammarus.

243 ■

Development of the European lobster. Abstract in American Journal Science and Arts, 3d ser.,
vol. 9, p. 231. New Haven, 1875.

244 •

Reports made to the Department of the Interior of investigations of the salt-water fisheries of
Norway during the years 1874-1877. (Indberetninger til Departmentet for det Indre fra
Professor G. O. Sars om de afham i Aarene 1874-1877 anstillede Undersogelser vedkommende
Saltvandsfiskerierne, Christiania, 1878.) Translated by Herman Jacobson, in Report U. S.
Fish Commission for 1877, p. 663-705. Washington, 1879.

245. SavildE-Kent.

The artificial culture of lobsters. International Fisheries Exhibition, London, 1883, The Fisheries
Exhibition Literature, vol. vi, Conferences, part 111, p. 327, 1 plate. London, 1884.

246. Say, Thomas.

An account of the Crustacea of the United States. Journal Academy Natural History, vol. 1, pt. 1,
p. 155-169 ( Astacus ), 235-253, 316-319, 374-401, 423-459, with appendix, observations, and
notes. Philadelphia, 1817.

247. SchERREn, H.

Meristic variations in Cancer pagurus and Astacus gammarus. Proceedings Zoological Society,
ser. 1903, vol. 2, p. 195-196. London, 1903.

248. Scott, Andrew.

On the spawning of the common lobster. Report for 1902 on the Lancashire and Sea-Fisheries
Laboratory at University College, Liverpool, and the Sea Fishery Hatchery at Piel, p. 20-27.
Liverpool, 1902.

Gives first detailed account of spawning of Homarus gammarus.

NATURAL HISTORY OF AMERICAN LOBSTER.

403

249. Seba, Albertus.

Locupletissimi rerum naturalium thesauri accurata descriptio et iconibus artificiosissimis expressio
per universam physices historiam, t. m, tab. xvn, no. 3. Copper-plate figure of lobster, called
Astacus marinus americanus. Amstelaedami, 1758.

Seba was the first to describe and figure the American lobster as a distinct species.

250. Sherwood, George H.

Experiments in lobster rearing. Report of special commission for the investigation of the lobster
and the soft-shell clam. Washington, 1903. Report of the U. S. Fish Commission for 1903,
p. 149-174, pi. 1-3. Washington, 1905.

251. Smith, A. C.

Notes on the lobster, Homarus americanus. Bulletin U. S. Fish Commission, vol. v, p. 121-125.
Washington, 1885.

252. Smith, Albert W.

Composition of the shell and gastroliths of the lobster. In The American lobster (see 149),
Appendix 11, p. 227-228, Bulletin U. S. Fish Commission, vol. xv, 1895. Washington, 1896.

253. Smith, Hugh M.

In Report of the special commission for investigation of the lobster and the soft-shell clam. (De-
cline of the lobster fishery.) Report of the U. S. Fish Commissioner for 1903, p. 141-148.
Washington, 1905.

253a. —

A review of the history and results of the attempts to acclimatize fish and other water animals in
the Pacific States. Bulletin U. S. Fish Commission, vol. xv, p. 379-472. (The American
lobster, p. 459-463.) Washington, 1895.

254. Smith, Sidney I.

The early stages of the American lobster ( Homarus americanus Edwards). American Journal
Science and Arts, vol. hi, p. 401-406, pi. ix. NewHaven, 1872. Abstract of fuller paper, no. 256.

255-

The metamorphoses of the lobster and other Crustacea. Invertebrate Animals of Vineyard Sound,
etc. (Verrill & Smith), in Report of the U. S. Fish Commissioner for 1871-1872, p. 522-537,
fig. 4 and pi. ix. Washington, 1873.

256.

The early stages of the American lobster ( Homarus americanus Edwards). Transactions Con-
necticut Academy of Arts and Sciences, vol. 11, pt. 2, p. 351-381, pi. xiv-xvm, fig. 1-4. New
Haven, 1873.

The best account at date of the metamorphosis of the American lobster.

257. Stahr, H.

Neue Beitrage zur Morphologie der Hummerschere, mit physiologischen und phylogenetischen
Bemerkungen. Jenaische Zeitschrift fur Naturwissenschaft, bd. 33, p. 457-482, pi. xx-xxi.
Jena, 1898.

First notice of periodic arrangement of teeth in toothed forceps of lobster.

tiber das Alter der beiden Chelae von Homarus vulgaris und fiber die “similar claws" Herrick’s.
Zur Verstandigung mit Herm Przibram. Archiv ffir Entwickelungsmechanik der Organismen,
bd. 12, p. 162-166. Leipzig, 1901.

239. Stebbing, Thomas R. R.

A history of Crustacea: Recent Malacostraca. International Science Series, vol. lxiv. New
York, 1893.

Advocates the use of the generic name of Astacus (Leach) instead of Homarus (Milne-Edwards), for the true
lobsters.

404

BULLETIN OF THE BUREAU OF FISHERIES.

260. Stebbing, Thomas R. R.

The lobster in commerce and science. Natural Science, vol. ix, p. 38-42. London, 1896.

A review of no. 14Q, with further arguments for the use of the name Astacus for the lobsters.

261. Stevenson, Charles H.

The preservation of fishery products for food. Bulletin of U. S. Fish Commission, vol. xvm,
1898, p. 337-564. Washington, 1899.

Describes methods of preserving lobsters, and of transporting them alive.

262. Thompson, J. V.

Letter to the editor of the Zoological Journal, dated "Cork, Dec. 16, 1830.” Zoological Journal,
vol. v, p. 383-384, pi. xv, fig. 13. London, 1831.

First announcement of discovery of metamorphosis in the European lobster ( Astacus marinus).

264. Thompson, William.

Description of a young lobster measuring only nine lines. The Zoologist, vol. ix, p. 3765. London,

1853-

264. Travis.

Letter to Thomas Pennant dated "Scarborough, 25th October, 1768.’’ Quoted in article on lobster
by Thomas Pennant (see 212), Pennant’s British Zoology, vol. iv, p. 10-13. London, 1777.

265. Tullberg, Tycho.

Studien fiber den Bau und das Wachstum des Hummerpanzers und der Molluskenschalen.
Kongliga Svenska Vetenskaps-Akademiens Handlingar, bd. 19, no. 3, p. 57, 12 taf. Stock-
holm, 1882.

266. Valenciennes, A.

Note sur la reproduction des Homards. Comptes rendus de l’Acad6mie des Sciences, t. 46, p. 603-
606. Paris, 1858.

267. Valentin, G.

Repertorium ffir Anatomie und Physiologie. Die Fortschritte der Physiologie im Jahre 1837,
bd. hi, p. 188. 1838.

Describes for the first time the rayed sperm cells of the lobster.

268. Van Beneden, P. J.

Note sur une pince de homard monstrueuse. Bulletin de I’Acaddmie Royale de Belgique, 2° ser.,
t. 17, p. 371-376, fig. Bruxelles, 1864.

26Q.

Bulletin de l’Acad£mie Royale de Belgique, t. xxvm, p. 444-456. Bruxelles, 1869. See also
Development of Gregarinae, Quarterly Journal Microscopical Science, vol. x, 1870, p. 290.

London. For reference to other work, see Foettinger, 108.

Describes gregarine parasitic in lobster.

270. Van der Hoeven, J. E.

Handbook of zoology. Translated from 2nd Dutch edition by Rev. William Clark. 2 vol.
Cambridge, Eng., 1856.

Discusses the function of the gastroliths, and was one of the first to protest against the theory that they served
merely to provide a store of lime to be drawn upon for hardening the soft shell.

271. VERRILL, A. E.

Report upon the invertebrate animals of Vineyard Sound and the adjacent waters, with an account
of physical characters of the region. Report U. S. Fish Commission for 1871-72, p. 295-778,
pi. i-xxxviii, with descriptions. Washington, 1873.

272. Vitzou, AlExandre-Nicolas.

Recherches sur la structure et la formation des tegumens chez les Crustaces decapodes. Archives de
Zoologie experimentale et generate, t. x, p. 451-576, pi. xxiii-xxvm. Paris, 1882.

NATURAL HISTORY OF AMERICAN LOBSTER.

405

273. Waite, F. C.

The structure and development of the antennal glands in Homarus americanus Milne-Edwards.
Bulletin Museum Comparative Zoology, Harvard College, vol. xxxv, no. 7,p. 151-210.pl. 1-6.
Cambridge, 1899.

274.

A large lobster. Science, n. s., vol. iv, p. 230-231. New York, 1896.

275. Wallengren, H.

tjber das Vorkommen und die Verbreitung der sogenannten Intestinaldriisen bei den Dekapoden.
Zeitschrift fur wissenschaftliche Zoologie, bd. 70, p. 321-346, 12 fig. Leipzig, 1901.

276. Weldon and Fowler, G. H.

Notes on recent experiments relating to the growth and rearing of food-fish at the laboratory. I.
The rearing of lobster larvae. Journal Marine Biological Association of the United King-
dom, n. s., vol. 1, no. 4, p. 367-375. London, 1890.

277. Wheildon, Wm. H.

The lobster ( Homarus americanus): The extent of the fishery; the spawning season; food of the
lobster; shedding of the shell; legislation on the fishery. Proceedings American Association
for the Advancement of Science, vol. xxii, p. 133-141. 1875.

278. Whitfield, R. P.

Notice of two very large lobsters in the collection of the American Museum of Natural History.
Bulletin American Museum Natural History, vol. xn, p. 191-194, pi. ix. New York, 1899.

The living weight of the animals described is given as 34 and 31 pounds.

279. Williams, Leonard W.

The stomach of the lobster and the food of larval lobsters. Thirty-seventh Annual Report of the
Commissioners of Inland Fisheries of Rhode Island, p. 153-180, pi. i-x. 1907.

Gives the first detailed and satisfactory account of the complex mechanism of the lobster’s stomach.

280. Williamson, H. Charles.

Contributions to the life-history of the edible crab ( Cancer pagurus Linn.). Eighteenth Annual
Report of the Fishery Board for Scotland, pt. hi, p. 77-142, pi. i-iv. Glasgow, 1900.

Argument for theory of annual spawning in the European lobster.

281. -

Contributions to the life-histories of the edible crab ( Cancer pagurus) and of other decapod Crus-
tacea; Impregnation; Spawning; Casting; Distribution; Rate of Growth. Twenty-second
Annual Report of the Fishery Board for Scotland, pt. hi, p. 100-141, pi. i-v. Glasgow, 1904.

Advances a new theory to explain the attachment of the eggs to the swimmerets of decapods.

282.

A contribution to the life-history of the lobster ( Homarus vulgaris). Twenty-third Annual Report
of the Fishery Board for Scotland for 1904, pt. 111, Scientific Investigations, p. 65-107, pi. i-iv.
Glasgow, 1905.

283. Wilson, Andrew.

The anatomy of the lobster. Science for All, vol. 2, p. 34-41, fig. 1-8 (appendages). London, 1879.

284. Wilson, E. B.

Notes on the reversal of asymmetry in the regeneration of the chelae in Alpheus heterochelis .
Biological Bulletin, vol. iv, p. 197-214. Boston, 1902-1903.

285. Wood, R. K.

The lobster. Chiefly a translation from a work of M. Coste to the Minister of the French Marine,
in “Land and Water,’’ London. Extract in American Naturalist, vol. 11, p. 494-496. Salem,
1869.

286. Wood, W. M.

Transplanting lobsters to the Chesapeake: Experiments upon the temperature they can endure.
Bulletin U. S. Fish Commission for 1885, vol. v, p. 31-32. Washington, 1885.

bulletin of the bureau of fisheries.

406

287. Young, John.

On the head of the lobster. Journal Anatomy and Physiology, vol. 14, p. 348-350, pi. xviii. Lon-
don, 1879.

288. Yung, E.

De la structure intime et du systfeme nerveux central des Crustaccs decapodes. Thkse. Paris,
1879.

289. Zeleny, Chas.

Compensatory regulation. Biological Bulletin, vol. n, p. 1-102, fig. 1-27. Boston, 1905.

290.

The regeneration of a double chela in the fiddler crab ( Gelasimus pugilator ) in place of a normal
single one. Biological Bulletin, p. 152-155. Boston, 1905.

291. A Manual of Fish-culture, based on the Methods of the United States Commission
of Fish and Fisheries.

Revised edition, i-x+1-340 p., numerous pi. Washington, 1900. The American lobster, p.

229-238.

Brief resume of methods of collecting and hatching the eggs, and liberating the young fry.

292. Annual Reports of the Department of Fisheries, with Supplemental Fisheries State-
ments, Dominion of Canada, from 1869 to the Present. Ottawa.

Contain many special reports and notices of the lobster, the most important of which are here mentioned
under separate titles.

29J. A LARGE LOBSTER.

The Zoological Society Bulletin. New York, 1908.

Record of specimen measuring 23-i 4 inches in length, and weight 34 pounds.

294. A SUCCESSFUL EXPERIMENT IN LOBSTER REARING.

Nature, vol. lvi, p. 455. London, 1897.

295. Culture du homard en Amisrique.

Bulletin Societe d’Acclimatation, 2e ser., t. 10, p. 957-960. Paris, 1873.

296. Fisheries statements, 1880.

Supplement no. 2 to Eleventh Annual Report to Minister of Marine and Fisheries. Appendix no.
11, Report of J. H. Duvar, Inspector of Fisheries for the Province of Prince Edward Island,
for 1880. Lobsters, p. 231. Ottawa, 1881.

297. Fisheries statements for the year 1882.

Supplement no. 2 to the Fifteenth Annual Report of the Department of Marine and Fisheries for
the year 1882. Ottawa, 1883.

298. Les pLcheries de la NorvLge.

Exposition Universelle de 1889 a Paris. Bergen, 1889.

Statistics on legal regulations of the lobster fishery, and upon the numbers and value of these animals annually
exported, from 1883-87.

299. Report of the lobster industry in Canada for 1892.

Supplement to the Twenty-fifth Annual Report of the Department of Marine and Fisheries, p.
1-38. Ottawa, 1893.

300. Report of the Canadian lobster commission.

Supplement no. 1 to the Thirty-first Annual Report of the Department of Marine and Fisheries, for
1898, p. 1 -41, with map. Ottawa, 1899.

301. Review of the Reports by Buckland and Spencer on the Lobster, Crab, and Oyster
Fisheries of Great Britain.

Quarterly Review, vol. 144, art. vi, p. 249-262. 1877.

NATURAL, HISTORY OF AMERICAN LOBSTER.

407

302. Sagacity of a Lobster.

Nature, vol. xv, p. 415. London, 1877.

303. The Cultivation of Lobsters.

Practical Magazine, vol. 2, p. 258-259. London, 1873.

ADDENDUM.

304. AppELL6f, A.

Undersolcelser over hummeren ( Homarus vulgaris) med saerskilt hensyn til dens optraeden ved
Norges kyster. Aarsberetning vedkommende Norges Fiskerier, 1 ste hefte. Bergen, 1909.

305 •

Untersuchungen iiber den Hummer, mit besonderer Beriicksichtigung seines Auftretens an den
norwegischen Kiisten. 1-80 p., pi. i-iii. Bergen, 1909.

This latest and in some respects the most detailed account of the habits and development of the European lobster
was not received until the present work was in press.

306. AlExandrowicz, Jerzy Stanilaw.

[The sympathetic nervous system of Crustacea.] Jenaische Zeitschrift fur Naturwissenschaft,
p. 395-444, 5 Pi-. 8 Jena, 1909.

Attributes to the sympathetic system the control of peristalsis and the regulation of automatic movements.

307. Dannevig, G. M.

Hatching lobsters and cod in Norway. Bulletin U. S. Fish Commission for 1886, vol. vi, p. 13-14.
Washington, 1887. See also on hatching of lobsters, Bulletin U. S. Fish Commission, vol. v,
1885, p. 280 and 446. Washington, 1885.

308. Ditten, S. H.

De la protection et de la reproduction du Homardetdeshuitres. See L. Vaillant: Rapport du Jury
international de 1 ’Exposition universelle de 1878, groupe vm, classe 84: Poissons, Crustaces et
Mollusques.

309. FriELE, M.

Notices sur les Pecheries de la Norwege . Impression a part du catalogue special de la Norwege a
l’exposition universelle de 1878 a Paris. Translated by J. Paul Wilson. Report U. S. Fish
Commission, 1877, p. 707-740. Washington, 1879.

310. Hadley, Philip B.

Additional notes upon the development of the lobster. Fortieth Annual Report of the Commis-
sioners of Inland Fisheries of Rhode Island for 1910, p. 189-190, pi. 1-34, with descriptions
of the appendages in stages 1 to 4. Providence, 1910.

311. (Jacobson, Herman, translator.)

Transporting lobsters in Norway. Translation of “ Forsendelse af Hummer, ” Norsk Fiskeritidende,
Bergen, 1886. Bulletin U. S. Fish Commission, vol. vr, 1886, p. 319-320. Washington, 1887.

312. Lund, Peter Wilhelm.

Zweifel an dem Dasein eines Circulationssystem bei den Crustaceen. Isis, p. 593-601, taf. 11, fig.
2-4. Leipzig, 1825.

313. Lund, P. W., and Schultz, A. W. F.

Fortgesetzte Untersuchungen liber das System des Kreislaubes bei den Crustaceen. Isis,
p. 1299. Leipzig, 1829.

314. MacMunn, C. A.

On the gastric gland of Mollusca and Crustacea: its structure and functions. Philosophical Trans-
actions of the Royal Society, vol. 193 B, p. 1-34; pi. 1-4. London, 1900.

313. Marchal, P.

Recherches anatomiques et physiologiques sur l’appareil excreteur des crustaces decapodes.
Archives de Zoologie exp6rimentale et generate, ser. 2, t. 10, p. 57-275. pi. 1-9. Paris, 1892.

BULLETIN OF THE BUREAU OE FISHERIES.

408

316. Meek, a.

The migration of lobsters. Report of the Northumberland Sea Fisheries Committee on the Scientific
Investigation for 1902, p. 40. Newcastle-upon-Tyne, 1892.

317. Nickerson, W. S.

On Stichocotyle nephropis Cunningham, a parasite of the American lobster. Zoologische Jalirbiicher;
Abteilung fur Anatomie. 8 bd. p. 447-480, taf. 29-31. Jena, 1905.

Of 100 lobsters examined 2 were infested with this parasite, which was encysted at the rectal end of the
intestine; 60-70 worms were found in one case, and but 1 in the other.

318. Owen, Richard.

Lectures on the comparative anatomy and physiology of the invertebrate animals, delivered at the
Royal College of Surgeons. Hunterian lecturesfor 1852, 2d ed., p. i-viii, 1-690. London, 1855.
See also Descriptive and Illustrated Catalogue of the Museum of the College of Surgeons, Physiological
series, vol. 11, p. 136, pi. fig. 1 and 2, and pi. 16, fig. 4, for figures and descriptions of Hunter’s
preparations of the arterial system of the lobster.

Figures heart of Homarus gammarus, and maintains that it carries mixed blood.

319. Perrin, Marshall L.

Transportation of lobsters to California. Report of the Commissioner, United States Commission
of Fish and Fisheries for 1873-1875, p. 259-266. Washington, 1876.

320. Prince, E. E-

Report on fish culture in Canada for 1903, p. 1-48. Ottawa, 1904.

321.

Report on fish breeding in Canada for 1904, p. 1-48. Ottawa, 1905.

322.

Report on fish breeding operations in Canada for 1906, p. 1-62. Ottawa, 1906.

323. Rathbun, Richard.

Notes on the decrease of lobsters. Bulletin of the United States Fish Commission, vol. iv, 1884,
p. 421-426. Washington, 1884.

324. Shearer, Cresswell.

On the anatomy of Histriobdella liomari. Quarterly Journal of Microscopical Science, vol. 55,
part 2, p. 287-360, pi. 17-20. London, 1910.

323. Smith, Hugh M.

The United States Bureau of Fisheries; its establishment, functions, organization, resources,
operations, and achievements. Proceedings of the Fourth International Congress, Bulletin of
the Bureau of Fisheries, vol. xxvm, 1908, p. 1365-1412. Washington, 1910.

326. Trybom, F.

Biologiska undersokningar 1901-1904. 1. Hummerundersokningar vid Sveriges vestkust. Ur

svenska hydrografisk-biologiska kommissionens skrifter. Haftet 2.

327.

Biologiska undersokningar 1901-1904. 11 och 111. Tillagg till redogorelsen for hummerundersokn-

ingar vid Sveriges vestkust aren 1901-1903. Haftet 3.

328. Report of the Commissioners upon the lobster and oyster fisheries of Canada for 1887, p. 1-66, i-iv.

Ottawa, 1888.

329. On the artificial propagation of the lobster; translated from Om Forsog med kunstig Udklaekning

af Hummer, ny raekke, in Nordisk Tidsskrift for Fiskeri, ny raekke, Tidsskrift for
Fiskeri, 2 en Aargang, p. 184-188. 1875. Report U. S. Fish Commission 1873-1875, p. 267-

270. Washington, 1876.

Bull. U. S. B. F., 1909

Plate XXXIII

° 0
w 5

<U -- .*->
C C oJ

£ g 6

O oS 3

T3 S

cd O w

^ ?.a

,g4J c

? s a

® Pc
°
<u ■ — ■

J2 o
W 3 3

•3^ £

Bull. U. S. B. F. , 1909.

Plate XXXIV.

Pod/> br v

Transverse section of body of female lobster in plane of gastric mill (see pi. xxxm). ad. m, adductor mandibuli muscle;
art , branchio-cardiac vessel, arth. br, arthrobranch; br. cav, branchial cavity; brs, branchiostegite; d. g. g, duct of
gastric gland; _/?. g. ch, basal flexor of great cheliped; g. g, gastric gland; ini. s, internal skeleton, in roof of sternal
sinus; n.(x), main nerve of great cheliped; p.g.m.i, first division of posterior gastric muscle; pi. br, pleurobranch;
Podo br, podobranch; t. ad. m, tendon of adductor mandibuli muscle; th. fl, floor of thoracic cavity.

■'f

Bull. U. S. B. F. , 1909.

Plate XXXV.

Fig. 3.

Fig. 4.

Fig. 7.

Fig. i. — Left eyestalk. from above, or from what was originally the anterior side, cor, transparent cornea, parts
of which are shown in figures 2 and 3; 1 and 2, segments of stalk, the homologies of which are doubtful.

Figs. 2 and 3. — Parts of corneal membrane of compound eye, composed of modified hexagonal facets of individual
eyelets, each being secreted by two corneal cells, the boundaries of which are indicated in figure 2. Enlarged
about no times.

Fig. 4. — Left first antenna from above, ck. s, chemical or “olfactory” setae of primary outer flagellum (Out. fgl );
mm, modified membrane over statocyst, which opens to outside by pore .

Figs. 5 and 6. — Left second antenna from upper and under sides. Ex, exopodital scale; End, long multiarticulate
“feeler”; v. gl, position of valve of green gland, which opens on under side of coxa (<7. gl ).

Fig. 7. — Left mandible from inner side; ab. m, opening muscle; t. ad. m., tendon of closing muscle; g, groove in
which palp ( p ) and upper lip work. Figures on plates xxxv-xxxix, unless otherwise designated, represent the
serial appendages from left side of a female lobster about iolA inches long and in hard shell, drawn to same scale,
as seen from anterior side, and but little under natural size. The segments of the permanent limb are num-
bered from base to apex.

Bull. U. S. B. F., 1909.

Plate XXXVI.

Fig. i.

Fig. 2.

Fig. 3.

Fig. 5.

Comb

Fig. 1. — Left first maxilla of adult, from inner side.

Fig. 2. — Left second maxilla. Ex, Ep, exopodital and epipodital divisions of respiratory fan or scaphognathite.

1, 2, partially divided plates of protopodite modified for mastication.

Fig. 3. — First maxilliped. fd, fold of epipodite, which forms trough in which inner blade of fan (fig. 2, Ep) works.
Fig. 4. — Left second maxilliped, showing fused third joint (*) and rudimentary podobranch.

Fig. 5. — Left third maxilliped, illustrating type of primitive two-branched limb, with functional podobranch,
but fused third joint (r), and Comb and cleaning brushes of third and following segments.

Figs. 5, a and 5, b. — Transverse sectional views of three-sided meros and ischium, to show comb and brush, in
planes indicated. In preceding and following plates, End represents the permanent inner branch of the limb;
Ex, the outer branch or exopodite; pro, the protopodite; ep, the epipodite; and pbr. the podobranch. See
legend of figure 7, plate xxxv.

Bull. U. S. B. F., 1909. Platk XXXVII.

Fig. i. — Right toothed forceps and cheliped of female lobster from lower side, showing periodic teeth, carpal ridge of
lower lock hinge, represented as if seen through hinge-process (/ h p), breaking joint (x), and interlock (s 1 and
s 3) between first and third podomeres. This claw is locked when closed by means of the underlapping lock
spine ( lock sp) and underlapping tip of dactyl, indicated by arrow.

Fig. 2. — Left cracker claw and cheliped of female from above, showing crushing tubercles, serial displaced teeth
on margin of “hand” {up. ser and l. ser), carpal groove of upper lock hinge {u h groove), absorption area of fourth
segment {Abs. a), breaking plane (at x), reversed basal hinges, or inner ball {h ball), and outer cup ( h socket)-, ten-
dons {l.jl 1 and t. ex 1) of first joint, podobranchia ( pbr ), gill separator (ep), and proximal spur ( ps ) of claw.

Figs. 3 and 4. — Base of great cheliped from below, disarticulated at second joint to show interlocking mechanism
or spines (j1, and j3) of first and third podomeres.

Bull. U. S. B. F., igog.

Plate XXXVIII.

Figs. 1-4. — Left second to fifth pereiopods or slender legs of adult lobster from anterior side, showing numbered segments of per-
manent limb, distribution of sensory tufts (.? ^), gills {pb, in fig. 1-3), and gill separators (ep), arrangement of ball-and-socket
basal hinges, median ball ( h , b ), and peripheral socket (h, s), tendons of basal joints {t.fi. 1, and t. ex. /), and cleaning pick
and brush {cl. br) of last leg. Star in figure 4 marks position of exopodite or outer swimming branch of thoracic limb, shed at
fourth stage.

Bull. U. S. B. F. , 1909.

Plate XXXIX.

Fig. 1.

Fig. ia.

Fig. 3.

Fig. 6.

Figs, i and ia. — Left first pleopod of female and male respectively, in the former representing a rudimentary endopodite, and
in the latter a styliform process modified for copulation

Fig. 2 and 2a. — Left second swimmeret of female and male lobster, respectively, the endopodite in the latter bearing a short spur.

Fig. 3. — Left third swimmeret, showing swimming setae (ss), and long, nonplumose hairs, modified for bearing the eggs, and
distributed in 7 groups, marked a g.

Fig. 4. — Left fourth swimmeret from egg-bearing female of approximately the same size as represented in preceding figure, and
drawn to same scale. Hair clusters a, b, c, and d catch the greatest number of eggs.

Fig. 5. — Left fifth swimmeret of series 1-3.

Fig. 6. — Left uropod, or modified swimmeret of tail fan, seen from the under or anterior side, in position corresponding to that of
preceding, showing 2-jointed exopodite (Ex) and marginal fringe.

Fig. 7. — The same appendage reversed, and seen from the upper side.

Bull. U. S. B. F., 1909.

Plate XL.

Left crusher claw of lobster, partly dissected from upper side, to show relations of muscles, nerves, blood vessels, and skin, with
principal branches of claw arteries and nerves laid bare art, large artery which supplies both muscles of claw, and breaks
into a regular system of branches in fine meat of tips; n (1), n (2), posterior and anterior nerve trunks supplying, respectively,
the extensor (Ex6) and thumb, and the flexor (fl6) and index.

Bull. U. S. B. F., 1909.

Plate XU.

Fig. 2.

Fig i. — Left second pereiopod from anterior or upper side, partly dissected to show the relations of muscles and tendons in the
principal segments; hinges (/?) and nerves (nl and n 2) are indicated; and extensor and flexor muscles (ex, H) are numbered
to correspond to segments of origin.

Fig. 2. — Shell of right toothed forceps in sectional view from above, to show tendons crossing distal joints. ^ //, lower sliding
hinge, from inside; mb, interarticular membrane (dotted line marking position of former tendon pocket).

mb.

-Ex

ex j

„ .h

h (ball;

\ 7 L

' Lfl

h(cup)

-eP

h __

t.ex4.

7 t

t.exl

Bull. U. S. B. F., 1909.

Plate XLII.

Fig. 1.

Fig. 2.

Fig. 3.

\ ' - -

/\^/vPWV

■

13 23

14342434

154 3 4 2 4 345

143 243

I JT JIT

Fig. 4.

/V./vTVv

:?Wv/Vv

[ •' V \/V\\4. V v:

[\wvva

1 3 2 34

14 3 4 2 4 3 45

1 5 4 3 4 2 545 345

1434524 3

i n nr

Fig. 5.

Fig. i. — Right toothed forceps of lobster in seventh -stage, seen from above, and drawn from molted shell. Dental armature of jaw,
marked a, shown greatly enlarged in figure 3.

Fig. 2. — Teeth from dactyl of lobster in fifth stage, showing multiple or bifurcate ducts of tegumental glands.

Fig. 3. — Serrate margin of jaw in area marked a, figure 1, embracing series i-ii, and showing spines pierced by the ducts of tegu-
mental glands. Cuticle only represented; enlarged about 170 times. Figures 1-3, from glycerine preparations and represented
in optical section.

Figs. 4 and 5. — Armature of index or propodus of right toothed forceps of lobster in seventh stage, and after molting to the
eighth, as seen from under side, showing changes in spines of each period introduced at this molt. L, lock spine, and Sp, spur.

Bull. U. S. B. F., 1909.

Fig. I.

Plate XU II.

Fig. 2.

Fig. 3.

- h(s )

~ up. ser

- - t-Ser

— P

Fig. 5.

Fig. i. Oblique section through large claw of lobster in first larval stage, showing open tendon pocket (t p) of adductor muscle;
before fusion of flattened cuticular walls has taken place.

Figs. 2 and 3. Jaws of cracker claw of lobster weighing about 12 pounds, disarticulated and placed to show correspondence of
“molars when jaws are closed. Proximal and distal tubercles of index (p. d) alternate with larger “crushers” of thumb
\Pl, dl) \ h\s), socket, and h{b), ball, of terminal hinge joint; up. and /. ser, upper and lower series of alternately displaced pro-
tective spines of propodus.

Fig. 4. Profile of seminal receptacle of female, from molted shell A , anterior; D, dorsal; Si, xiu, modified sternum of somite
xiii; bar, sternal bar, supporting seminal sac, x with dotted line marks plane of section of seminal sac shown in figure 3, plate
xuv; 5, proximal socket of first joint of fourth pereiopod.

Fig. 5. Skeleton of first abdominal somite of male from behind, showing stylets directed forward and meeting on mid-line, their
probable position for conveyance of spermatophore to seminal receptacle in impregnation. A, anterior, and p , posterior
margin of somite; 6, posterior ball of hinge joint; /, tergum; ep, epimeron; st, sternum; pi, reduced pleuron, which forms “but-
ton” to carapace.

Fig. 6.— Seminal receptacle shown in profile in figure 4, as seen from under side, presenting median elastic lips of pouch into
which nibs of stylets are supposed to be pressed in copulation. Figures 4-6, nearly natural size.

Bull. U. S. B. F., 1909.

Plate XLIV.

Fig. 5.

Fig. i. — Immature ovary of lobster with abnormal ring on left anterior lobe for transmission cf left antennal artery {ant. art )
H , heart.

Fig. 2. — Reproductive organs from right side of male, dissected to show sperm duct, and spermatophore ( Sph ) pressed from slit
made in its side, p. s, gl. s, sp. mu9 duct . ejac, proximal segment, glandular segment, spnincter muscle, and ductus ejaculator-
ius of vas deferens; pap, papilla for opening of duct on coxa of fifth pereiopod.

Fig. 3. — Transverse section (in plane x, fig. 4, pi. xliii) of homy pouch of seminal receptacle of female lobster, showing contained
spermatophore (Sph), gelatinous coats (g), and soft substance on lower side (w) over sternal bar. a. Anterior; p, posterior

Fig. 4. — Left third swimmeret of female, 9 V2 inches long, with bifurcated endopodite; anterior side.

Fig. 5. — Tobster’s egg, showing its two membranes ruptured and greatly distended by reagents; mb1, primary membrane or
chorion; mb2, cement membrane of attachment, forming bag continued into basal stalk

Bull- U. S. B. F., 1909.

Plate XLV.

ov. w

Fig. 3.

GL'.ejj

Fig. 4.

Fig. s.

Figs. 1-5. — Diagrams to illustrate structure and growth of ovary of the lobster from first larval stage to maturity. Note the
primordial epithelium in larva (p. ep, fig. 1), the germogenal folds ( Ger.fd . fig. 3), and reentrant blood sinuses (Bl. .y) formed
by foldings of this layer, the multiplication of epithelial cells along the crests of these folds, and their differentiation into ova
and follicle cells (see fig. 1, pi. xlvi), the development of glandular pouches after eggs are laid (fig. 4), and their recession
when thelatterare ripe. Figure 1, from larva; figures 2 and 3, from early and late adolescent stages; figure 4, from adult with
ovary nearly ripe; figure 5, from adult, 36 hours after extrusion of ripe eggs. Bl. v, blood vessel; fol, egg-follicle; Gl. ep, glandular
epithelium; 01;. ep, ovarian epithelium; ov. w, ovarian wall.

Bull. U. S. B. F., 1909.

Plate XL,VI.

Fig. 3.

Fig. i. — From transverse section of ovary of lobster inches long, July 25, showing cluster of epithelial cells on crest of fold,
and their differentiation into primordial ova ( el ) and follicle cells ( fol . ep), with formation of egg-sacs (fol); b. m, basement
membrane; Bl. s, blood sinus; ov. ep, epithelium of ovary. Enlarged about 230 times

Fig. 2. — Part of longitudinal section of first larva, at point of attachment of adductor mandibuli muscle (ad. m), showing fibillar
modification of epithelium ( fb . ep), and basement lamella (6m); bl. v, blood vessel; cut, cuticle; ms, mesoblast. Enlarged
about 230 times.

Fig. 3. — Part of transverse section of dactyl of soft lobster, close to spines of dentate margin, showing the enamel ( En ), pigmented
and calcified layers of shell (p. and c. /), chitogenous epithelium (ch. ep.), and involuntary muscle spongework (;. mu), with
blood lacunae (bl. 1), in “fine meat” of claw tip; 6. c, blood corpuscles; s, seta. Enlarged about 115 times.

Bull. U. S. B. F. , 1909.

Plate XLVII.

Fig. i. — Part of section parallel to long axis of gill, showing three transverse rows of filaments, cut crosswise, and their double
tubular character; af and ef , afferent and efferent division of filament. Enlarged 27 times.

Fig. 2. — Diagram of transverse section of lobster’s gill, viewed as a transparency, to show probable course of circulating blood
as indicated by arrows; af. v, branchial stem afferent; ef. v, branchial stem efferent; c v, circular vessel;/, gill filament The
relations of the two divisions of the filament to the two divisions of the stem are shown in but few cases only. All filaments
communicate with the stem afferent on the one hand and with the stem efferent on the other

Fig. 3 — Transverse section of oviduct of adult lobster immediately before egg-laying, showing its glandular lining epithelium
greatly distended.

Fig. 4.— Transverse section of oviduct of adult lobster taken immediately after egg-laying, showing the shrunken and vesiculated
character of its epithelium.

ANATOMY AND PHYSIOLOGY OF THE WING-SHELL
ATRINA RIGIDA

By Benjamin H. Grave

Assistant Professor of Zoology, University of Wyoming

409

CONTENTS.

J-

Page.

Introductory 41 1

Shell 412

Mantle 413

Burrowing 414

Regeneration and growth of shell 414

Mantle gland 416

Labial palps 417

Gills 418

Structure of the filaments 421

Course of the circulation in the gills 422

Respiratory current 424

Food-bearing currents 423

Circulatory system 425

Arterial system 426

Venous system 427

Adductor muscles 428

Retractor muscles of the foot 428

Visceral mass 429

Foot and byssus 429

Kidney 429

Digestive tract 431

Nervous system 432

Sense organs 435

Otocysts 43 S

Osphradium 436

Summary 436

Bibliography 437

Explanation of plates 438

410

ANATOMY AND PHYSIOLOGY OF THE WING-SHELL ATRINA

RIGIDA.8

By BENJAMIN H. GRAVE,

Assistant Professor of Zoology, University of Wyoming.

INTRODUCTORY.

Atrina rigida (Dillwyn) occurs along the eastern coast of America from the north-
ern shore of South America as far north as Cape Hatteras. At Beaufort, N. C., where
most of the observations reported in this paper were made, this species is confined to
shallow water near low-tide mark, occasionally being exposed during unusually low
tides. Another species, Atrina serrata (Sowerby), is found in the deeper water of the
inlet. The largest specimen found measured 14 by 9 by 3 inches, but the average size
is only about 11 by 8 by 2% inches.

This mollusk is not without an economic interest and value. The black pearls
formed in Atrina and Pinna , and produced in considerable numbers, have been used in
the manufacture of brooches and other articles of jewelry, and there is no reason why
they should not be used more extensively. They are usually spherical in shape and
quite smooth.

The pearls are not found in all specimens, but as many as ten have sometimes been
found in a single individual. At a rough estimate I should think pearls would be found
in about one-fifth of the individuals. This was about the proportion as regards those
examined during the preparation of this paper.

The byssus has been used extensively in the manufacture of various articles, such as
shawls, caps, waistcoats, gloves, purses, etc. The following quotation from Simmonds’s
Commercial Products of the Sea gives in a few words the extent to which the byssus
has been used in the past, as well as its present standing as a commercial product :

The ancients made this [the byssus] an article of commerce, greatly sought after, and the robes
formed of it, called “tarentine,” were very much in esteem. *****

a Dissertation submitted to the Board of University Studies of the Johns Hopkins University in conformity with the require-
ments for the degree of doctor of philosophy.

I am indebted to Prof. W. K. Brooks for the suggestion that I undertake the study of the anatomy of Atrina.
My thanks also are due especially to Prof. E. A. Andrews, under whose direction this work has been done and who has
offered many helpful suggestions and stimulated my interest in biological study. I am indebted to the Commissioner
of Fisheries for the use of a table at the fisheries laboratory at Beaufort, N. C., during the summers of 1908 and 1909;
to H. D. Aller, director of the laboratory, for many conveniences while there and for assistance in procuring material;
to Prof. G. A. Drew for counsel and suggestions; and to Prof. William H. Dali, of the Smithsonian Institution, for the
determination of the species and the free use of his library.

412

bulletin of the bureau of fisheries.

Even in the present day the fiber is utilized, but more for its rarity than anything else. The women
comb the lana fbyssus] with very delicate cards, spin it, and make from it articles which are much
esteemed for the suppleness of the fiber and their brilliant burnished gold luster.

A considerable manufactory is established at Palermo; the fabrics made are extremely elegant
and vie in appearance with the finest silk. The best products of this material are, however, said to be
made in the Orphan Hospital of St. Philomel, at Lucca.

This byssus forms an important article of commerce among the Sicilians, for which purpose con-
siderable numbers of Pinna are annually fished up in the Mediterranean from the depth of 20 to 30 feet.

Under normal conditions Atrina occupies one position during its entire life —
nearly buried in the mud, with its anterior end downward. The enormous byssus
extends deep into the mud and attaches to shells and coarse pebbles. Specimens are
most easily collected in calm weather at low tide, when they can be seen extending an
inch or less above the surface of the mud.

* In the following discussion, although the continuity is thereby interrupted, it seems
advisable to treat the organs under separate headings, passing briefly over those which
have yielded nothing of particular interest. To avoid repetition the anatomy and
physiology of the organs will be treated together. The general anatomy is shown in
figures 16 and 20.

Since every species is adapted to its peculiar mode of life certain anatomical features
are better understood when their function is known. It has therefore been my pur-
pose to study habits and function as well as anatomy.

SHELL.

The shell valves are large in comparison with the size of the body, and they are
united to each other along one side by a hinge ligament which extends in a straight
line from their anterior to their posterior ends. The hinge ligament is more or less
calcified, so that it is not greatly different from the other parts of the shell. The outer
surface of each shell is studied with spines, which are distributed in rows radiating
from the anterior pointed end as a center to the posterior end. Primary, secondary,
and tertiary rows of spines may be distinguished in the shell of a large specimen. The
portion of the shell which lies posterior to the adductor a consists of a single layer in
contrast to the typical lamellibranch shell, which has three layers, easily distinguishable
by difference in structure or material. It apparently corresponds to the middle or pris-
matic layer of the typical lamellibranch shell, being composed of prisms which lie at
right angles to the surface. When the surface is examined with a compound micro-
scope it appears honey-combed, while a transverse section, obtained by grinding, looks
not unlike a lot of quartz crystals corded like wood. (See fig. 1.) It is possible to
dissolve out the lime salts with acid, leaving behind only the organic matrix. This
matrix resembles cork in many respects, but when examined histologically it is seen to
have the same gross structure as the shell before treatment with acid, except that the
chambers formed by the organic matrix are now empty.

a I refer here to the posterior adductor muscle, and unless otherwise stated further references to the adductor may be taken
to mean the posterior adductor.

ANATOMY AND PHYSIOLOGY OF ATRINA RIGIDA.

413

The portion of the shell in the region of, and anterior to, the adductor is composed
of two layers, there being a second or nacreous layer of the ordinary type deposited
upon the inner surface of the prismatic. This layer is secreted by the general surface of
that part of the mantle which lines the shell in these regions. The outer layer fre-
quently wears through, or becomes brittle and broken, on the older portions of the
shell, leaving the nacreous layer exposed. A discussion of experiments on the growth
and regeneration of the shell will be found at the end of the next section.

MANTLE.

The mantle is a muscular membrane, the folds of which adhere closely to the shell,
but are attached to it only at a single point just ventral to the adductor muscle. The
muscles which control the ventral and posterior portions of the mantle are attached
here and radiate from this point as divisions and subdivisions of a single bundle.
Another bundle of muscle fibers is located near the dorsal part of the body. It is
not attached to the shell at any point, but is inserted into the mantle itself. This
bundle of mantle muscles also divides and subdivides into
smaller and smaller bundles and is distributed to a portion
of the posterior part of the mantle. (Fig. 16, pi. XLVIII.)

It is thus seen that there is no pallial line in the shell for
the attachment of the mantle muscles, though that is so
common among lamellibranchs. Since the muscles are
attached so high up, the mantle margin can be withdrawn
a considerable distance from the edge of the shell; in fact,
it can be withdrawn nearly to the adductor. After being
contracted the mantle again expands by creeping outward
upon the shell, to which it adheres closely. This result can
not be brought about at once. At least half an hour is
required for the mantle to again reach the edge of the shell after having been fully
contracted. There are no siphons, but the two lobes of the mantle are united poste-
riorly by an intermantle septum at the place where siphons might be expected to
occur. This structure consists of two prominent ridges, one on each mantle lobe, which
stretch across posterior to the gills to meet each other in the mid line. Each mantle
ridge is continued anteriorly, though reduced in size, and forms the place of attach-
ment for the upper borders of the reflexed lamellae of the outer gills.

On account of the position assumed by Atrina, only the posterior portion of the
mantle is exposed to frequent sensory stimulation. Connected with this fact we find
that the edge of each mantle lobe has a row of short sensory tentacles, which decrease
in size and gradually disappear toward the anterior end. This part of the mantle is
thick and muscular, as an adaptation to burrowing. A deep narrow passage or groove,
formed by the development of two tall ridges on the inner surface of the mantle, is also
correlated with burrowing. (Fig. 16, D, pi. xlviii.) This groove lies parallel to the
edge of the mantle and extends from the region of the foot to the intermantle septum,

Fig. 1. — The shell, a, Surface view;
b, transverse section showing prismatic
structure.

4:4

bulletin of the bureau of FISHERIES.

where it approaches the edge of the mantle. The cilia within this groove beat toward
the posterior to produce currents that continually remove foreign bodies from the
mantle chamber. Any large particle of dirt or sand which enters the mantle chamber
soon finds its way into this ciliated passage and is carried forthwith to the exterior.

BURROWING.

In order that Atrina may maintain its position in the mud throughout life, it must
burrow more or less. The bottom about it is sure to be shifted considerably by the tides,
thus tending to uproot or cover up fixed objects on its surface. This shifting of the
bottom was observed last year on the very beds where Atrina was found most abundant.
During the summer of 1908 these beds were covered by eel grass, while a year later this
grass had entirely disappeared and the character and depth of the bottom had changed
to a noticeable extent. Atrina while undisturbed in its natural surroundings was never
seen to burrow. But the method of burrowing was frequently observed when the
animal was removed and again partially buried with the anterior end downward. The
shell valves were opened wide by the relaxation of the adductor muscle, and the edges
of the posterior part of the mantle lobes were brought together firmly to prevent the
escape of water in this direction. Then followed the contraction of the adductor,
forcing water from the mantle chamber at the anterior end. The force of the expelled
current makes the water fairly boil, washing up quantities of sand and mud from
beneath. This process was usually repeated several times at intervals of four or five
seconds and then there followed a period of rest during which the sand and mud which
had entered the mantle chamber during the burrowing movements was removed through
the ciliated groove. This heavy material was expelled over the posterior edge of the
shell in surprisingly large quantities in a short time. This accomplished, the burrowing
movements were resumed. The settling of the specimen was very gradual, but in the
course of an hour one could see that it had sunk 3 or 4 inches. Although the ciliated
groove is of service in removing solid particles which enter the mantle chamber with
the respiratory current, I think it is an especial adaptation for removing the heavier
bodies which enter the mantle chamber during burrowing movements.

A number of Atrina individuals were laid upon their sides to see if they would
bury themselves. The results were practically negative, for although they were left for
weeks in this position not one made any attempt to bury itself. They seemed to thrive
as well in this position as in any other, and none were seen to make movements which
could be construed as an attempt to assume the normal position. Mr. Charles Hatsel,
official collector at Beaufort, in whose charge certain experiments were left during the
winter, reported that one specimen buried itself as far as the box in which it was kept
would permit.

REGENERATION AND GROWTH OF SHELL.

Atrina is a particularly good subject for experiments upon the growth and regenera-
tion of the shell because of the great rapidity with which this is produced. When one
breaks a piece from the posterior or ventral edge of the shell, the mantle in this region
becomes particularly active in mending the breach, a strip one-tenth of an inch in width

ANATOMY AND PHYSIOLOGY OF ATRINA RIGIDA. 415

often being produced in twenty-four hours, the amount varying in different specimens
between one-eighth and one-twelfth. In one instance a hole which measured approxi-
mately one-half by three-fourths of an inch was cut in the shell of a vigorous young
Atrina with the result that it was repaired in three days. Experiments performed to
determine what parts of the mantle are capable of producing shell go to show that this
power belongs only to the very edge and is probably confined to a small portion of
modified epithelium located in a groove in the edge of the mantle.® (Fig. 2, a.) When
a notch was formed in the shell by breaking out a
piece, the edge of the mantle was quickly applied to
the bottom of it with the result that it was soon built
up even with the general level of the edge of the shell.

When holes were cut in the shell at a great distance
from the edge to see if other portions of the mantle
could produce shell, it was found that the mantle edge
was drawn back to these places and remained there
until they were repaired. Although conclusive proof
that only the edge of the mantle can produce shell is
lacking, there is abundant evidence that Atrina gener-
ally repairs all injuries to the shell with this part of the
mantle, and it seems safe to assume that shell forma-
tion is confined to this portion.®

As stated in a previous section, the outer surface
of the shell bristles with spines, which are distributed
in rows. They have the same prismatic structure as the
shell and like it they are secreted by the edge of the
mantle. When fullyformed, theyare between one-half
and three-fourths of an inch in length, and, except that
they are slightly broader at the base than at the top,
have the shape of a half tube, the hollow side of which
faces the edge of the shell. During the growth period
of one of these spines a little fold or tongue of the
mantle edge extends beyond the shell and fits into the
hollow surface of the spine. In time the shell, by its
growth at the edge, extends beyond the spine so that the mantle no longer comes into
contact with it. This mode of formation accounts for the fact that the spines are
hollow and open toward the growing edge of the shell. There is no visible differentia-
tion of the mantle edge in the form of permanent folds to which the formation of the
spines is due. The edge of the mantie opposite a row of spines does not seem to
differ from that located between two rows. The tongues which creep out into the
spines are not permanent structures, but are formed by a local expansion of the mantle.

o This refers only to the prismatic layer. The second layer, which is laid upon the inner surface of the shell at the anterior
end, is secreted by the whole of the epithelium of the mantle of this region.

Fig. 2. — Diagrammatic cross section of the
body anterior to the adductor muscle, a,
Modified epithelium which secretes shell;
bt suspensory membrane; c, descending
lamella of outer gill; d, reflected lamella;
ey longitudinal ridge on the mantle to which
the gill is attached by means of interlock-
ing cilia; f, vascular interlamellar septum;
g , longitudinal groove in edge of gill, i, 2,
and 5, suprabranchial chambers.

416

bulletin of the bureau of fisheries.

Measurements to determine the rate of growth of Pinna under natural conditions
revealed slower growth than had been anticipated. In seven weeks’ time some speci-
mens increased one-half inch in length with corresponding increase in breadth. The
greater number grew only about one-fourth of an inch in this time and the oldest speci-
mens showed no growth. It is impossible to estimate from these figures the time required
for an individual to reach maturity, but the fact is revealed that when they reach a
certain age growth ceases.

At the suggestion of Professor Andrews I endeavored to discover whether the
calcium salts used in shell formation are taken directly from the sea water or whether
they are taken from the blood. The results are not satisfactory, but I give them for
what they are worth: A notch was cut in the shell of a young specimen and the broken
edges were filed until they were quite smooth. The specimen was then placed in artificial
sea water which lacked only the calcium salts. This water was kept aerated by com-
pressed air. The specimen applied the mantle edge to the broken place in the shell and
kept at work for several hours without accomplishing much. During the first experi-
ment, which was continued for twenty-four hours, only about one-tenth as much shell
was produced as would have been formed under normal conditions. However, enough
was produced to be plainly visible and when it was removed and examined under the
microscope it showed normal structure and effervesced when hydrochloric acid was
added.

Several similar experiments were tried, but no perceptible growth of shell was
obtained. In the first experiment the chemicals used were not “C. P. ” and may have
had some calcium in them, and this may account for the lack of uniformity in the results.
It was impossible to keep the specimens in good condition for twenty-four hours in this
artificial sea water and on this account I think it unwise to draw hard and fast con-
clusions from the experiments. The method seems worth trying under more favorable
conditions. Recently the question has been raised as to whether animals which live in
a water medium can take nourishment from it through the general body surface. It
seems quite possible that lamellibranchs take the lime salts from the water directly
rather than indirectly from the digestive tract. If lamellibranchs elaborate shell from
calcium salts in the blood, their supply must be continually replenished, judging from the
above experiments, which indicate that these specimens could not make much headway
from stores already present in the body.

MANTLE GLAND.

A large muscular structure, which appears from its connections to have been devel-
oped from the mantle, lies in the cloacal chamber. It resembles the foot in many respects
and, like it, can be extended by blood pressure. When extended it becomes slender and
mav reach a length of nearly 6 inches, but when contracted it is short and thick. Upon
its tip it bears a large mucous gland. (Fig. 16, M, pi. xlviii.) This peculiar organ is not
commonly found in lamellibranchs, being confined to the Pinnidae. Many specimens
were examined in their natural habitat and in the laboratory for the purpose of learning

ANATOMY AND PHYSIOLOGY OF ATRINA RIGIDA.

417

its function. So long as a specimen is undisturbed this glandular structure is likely to
lie quietly in the cloacal chamber, but when the mantle is irritated, for example by break-
ing off part of the shell, it becomes active and moves about in every conceivable direction.
It was frequently pushed far down into the branchial chamber toward the point of irri-
tation. When grains of sand were put upon the mantle this muscular gland sometimes
succeeded in brushing them off after several trials and much aimless maneuvering. While
this organ is moving about the glandular tip is usually kept pressed against the mantle and
appears to be sweeping its surface. It seems to be a “ swab ” for the purpose of freeing the
mantle of any foreign body which may lodge upon it.

Just why the Pinnidse need such a structure isdifficult to determine, since other lamel-
libranchs get on without it, the cilia on the inner surface of the mantle being equal to
the task of keeping it clean. The position assumed by Atrina is one of disadvantage for
removing debris. It has been pointed out that great quantities of dirt and sand do
enter the mantle chamber, and this must all be raised vertically to the edge of the shell
for expulsion, so that structures especially adapted to this purpose are to be expected.
The mantle gland is probably such a structure.

The mantle gland is much less compact in structure than the foot. On the outside
there is an epithelial covering which is glandular only at the tip of the organ. Here
the cells are very much elongated and they contain a large amount of secretion in the
form of granules. Immediately beneath the epithelium there is a band, or cylinder, of
longitudinal muscle fibers. They are attached to the organs at the base of the gland
for support. Many of them spread out over the adductor, into which they are inserted.
They are so distributed in the gland that they can control the direction of its movement
provided that they do not all contract at the same time. The shortening of the gland
is also brought about by the contraction of these muscles. The central part of the gland
is composed of very open connective tissue and a few transverse muscle fibers.

LABIAL PALPS.

The palps consist of two thin muscular lamellae which extend across the anterior end
of the body, one above and the other below the mouth. Their outer ends are roughly
triangular in shape and lie alongside the body. The epithelium lining the palps is
continuous with that of the mouth and Drew (2) has aptly likened these structures to a
pair of drawn-out lips. They are essentially alike in many lamellibranchs but vary
greatly in size and shape in different species. In Atrina they are comparatively large
and consist of two well-defined portions. That part which lies near the mouth is narrow
and is lined by a smooth ciliated epithelium, while the outer triangular portion is broad
and is lined by an epithelium that is thrown into a series of prominent ridges and grooves
large enough to be plainly seen without magnification. Posteriorly the palps inclose the
anterior ends of the gills, and it is their function to transport the food collected by these
organs to the mouth. An extra projecting membrane is present on the ventral border
of the inner palp, which folds up over the outer. (Fig. 16, pi. xlviii.)

48299°— Bull. 29 — 11 27

4i8

bulletin of the bureau oe fisheries.

GILLS.

There are two large gills on each side of the body which extend parallel to its longi-
tudinal axis from the neighborhood of the mouth almost to the posterior extremity of
the mantle. (Tig. 16, pi. xlviii.) They are attached to the body by a suspensory mem-
brane in the usual manner. The gills are much alike except that the inner one of each
pair is somewhat broader than the outer and hence reaches below its fellow. They are
pointed at the extremities and anteriorly are inclosed by the palps. Each gill consists
of two lamellae which lie close together; or perhaps it is more correct to think of it as
being composed of a single lamella which has been folded upon itself. According to this
conception, the gill consists of a direct and a reflexed lamella, the two being continuous
at the free edge of the gill. Various anatomical and embryological studies, especially
those of Eacaze-Duthiers (8) and Peck (12), show this to be the correct interpretation.
The two lamellae are united to each other merely by blood vessels which pass from the one
to the other. The interlamellar space is not partitioned off into definite parallel water
tubes by continuous septa, but is undivided except for the scattered blood vessels which
traverse it. The only place where there is anything resembling true interlamellar septa
is at the upper borders of the gills where nonvascular, or only partially vascular, strands
bind the two lamellae together. At the outer free edge of the gill they are bound firmly
together by lacunar connective tissue and by a continuous plate or cord of muscle
whose fibers run longitudinal to rather than transverse to the gill. By its contraction
the gill is shortened and folded. A large nerve lies immediately above this muscle, but
I have made no attempt to study its distribution.

Each gill is attached to the suspensory membrane by one lamella only, as is common
among lamellibranches. The inner lamella of the outer gill and the outer lamella of the
inner gill are attached to the suspensory membrane as far back as the adductor muscle.
From this point they are attached to each other. The outer lamella of the outer gill
is attached to a ridge on the mantle (the same as that mentioned above). The inner
lamellae of the inner gills of the two sides are united to each other, except at the extreme
anterior, where for a space of half an inch or so they are attached to the sides of the
byssal apparatus which with the foot extends ventrally at this point. The attachments
of the gills, together with the intermantle septum, thus cut off a system of supra-bran-
chial passages from the general mantle cavity. A section across the body shows that
there are three of these, which are diagrammatically represented in figure 2 (r, 2, and 3).
A section taken posterior to the visceral mass would show only a single suprabranchial
passage, the three having been thrown together at the termination of the suspensory
membranes. This single suprabranchial passage lies below and posterior to the adduc-
tor muscle, and for distinction might be called the cloacal chamber.

The direct lamellae are outgrowths from the suspensory membrane, and hence
there is a firm organic union between them. On the other hand, the attachment of the
upper borders of the refiexed lamellae to the neighboring parts and of the ridges on the
mantle to each other, to form the intermantle septum, is merely an interlocking of cilia
so that they can be torn apart without doing the slightest injury to the animal. Only

ANATOMY AND PHYSIOLOGY OF ATRINA RIGIDA.

419

a slight pull is necessary to separate them. In this way the branchial and suprabran-
chial chambers can be thrown together. In fact, the animal can maintain them separate
or throw them together apparently at will. These unions commonly show an inter-
locking of the epithelial cells as well as the cilia, and sometimes the epithelium of the
opposed surfaces is thrown into a series of ridges and grooves, thus producing a firmer
union. Although Lacaze-Duthiers (8) and Peck (12) have described forms in which
there is a weak union between the upper borders of the reflexed lamellae and the mantle,
they did not describe the actual mode of union. Their purpose in the description was to
show the transition between those forms which have the mantle edge free and those
which have it permanently united to the neighboring parts. Grobben (5) has shown
that this weak union is by means of interlocking cilia, and he considers it to be universal
among the Aviculidae. He states also that when the opposed surfaces are forcibly
separated they will reunite in a short time if undisturbed. The evidence upon which
this assumption was based was his observations on the gill of Mytilus. Here he found,
what Lacaze-Duthiers had already described, that the ciliary interfilamentar connectives
would reform after being separated. Stenta (14) demonstrated that the reflexed lamellae
of the gills of Pinna and Solen would reunite to adjacent parts after being separated
from them, and I have confirmed the same for Atrina. I separated the gill from its
attachment to the mantle for a distance of 2 inches. When examined several hours
later it had effected a union. Stenta thinks that this type of union between the gills
and mantle is of much more general occurrence than has been supposed, suggesting
that it may occur in those forms in which the gills have been described as free. He
maintains that in life they are never separated unless by accident, but he is probably in
error, because I observed the mantle gland, which normally lies in the cloacal chamber,
extending far down into the branchial chamber. This could not take place so long as the
gills retained their connection with each other.

When magnified sufficiently each lamella is seen to be thrown into a series of folds
(grooves and ridges). These structures are barely visible to the unaided eye as a series
of parallel lines running across the gill perpendicular to its base. Each ridge (fig. 3)
is composed of from 10 to 12 hollow filaments which are slightly separated from each
other. The latter are bound together at regular intervals by tubular interfilamentar
connectives which are somewhat larger than the filaments and run at right angles to
them. These two sets of tubules thus form a trelliswork in which the spaces between
are the ostea through which water enters the gill from the branchial chamber. (Fig. 4.)
The one or two filaments which occupy the summit of the ridge differ somewhat from
the others in that they contain numerous goblet cells whose sticky secretion entangles
minute organisms as they are carried over the gills in the respiratory current. The fila-
ments and ridges of one lamella do not pass directly over into those of the other, but
gradually decrease in size and disappear as they approach the edge of the gill. There
is a deep groove with smooth walls in the edge of each gill which is lined by ciliated
epithelium. (Fig. 2, g.) There is no fusion of filaments due to crowding as has been
described by Rice for Cardium and other forms (13).

420

bulletin of the bureau of fisheries.

The grooves which lie between the ridges just described are not filamentous in
structure but are lined by a continuous finely ciliated epithelium, below which there is
a large crescent shaped rod of chitinous material for giving rigidity and elastisity to the
gill. (Fig. 3, c.) Running along the floor of each groove within the cavity of the gill
there is a large blood vessel. Each is connected with the similar vessels which lie next

Fig. 3. — Transverse section of gill highly magnified, a, Modified filament containing glands; b, vascular
interlamellar connective; c, chitinous supporting rod; d, large blood vessel; e, epithelium; /, filaments;
m, muscles; n, nerves.

to it, at regular intervals, by smaller tubes which are the interfilamentar connectives
already described as binding the filaments together. All of these structures are hollow
and the cavities of all are in open communication. Thus when blood enters the gill it
penetrates every part, including the filaments and interfilamentar connectives. (Fig. 4.)
It is common to regard the structures which occur between two folds of the lamella as

ANATOMY AND PHYSIOLOGY OF ATRINA RIGIDA.

421

a large modified filament, or as a single filament with its subsequent development of
subfilamentar lacunar tissue, and there is some evidence that this is correct, viz, the
epithelium lining the ciliated groove is continuous with that of the blood vessel. (Fig.
3, e.) At the edge of the gill also the resemblance becomes much more striking where
it assumes clearly the appearance of a filament.

STRUCTURE OF THE FILAMENTS.

The structure of the individual filaments is best made out in cross sections such as
that represented in figure 5. Each is composed of a simple epithelium which is lined
by a very thin layer of chitinous material resembling a cuticle. (Fig. 5,c). Peck (12)
considers this lining cuticle to be modified lacunar tissue. Sometimes protoplasmic

Fig. 4.— Diagrammatic drawing of a bit of the gill, b, Interlamellar connectives; f filaments; i, interfila-
mentar connectives; v and v' , large blood vessels. The arrows indicate the direction of the flow of the
blood.

corpuscles can be seen lying upon its inner surface but none have been detected within
it. There are no transverse bridges of this material such as are uniformly present in
the filaments of the lower forms (Area, Mytilus, and Pecten). It has commonly been
supposed that the septum in these forms divides the cavity of the filament into two
blood channels — the one afferent the other efferent — and this view seems well founded.
Drew (2) by use of injections found that in Pecten this bridge had no such physiological
significance. He has therefore suggested that it may serve to prevent the walls of the
filament from spreading under the pressure of the inclosed blood which might close the
incurrent ostea of the gill. He thinks that further study of gills of similar structure
might throw light upon this interesting point. The gill of Atrina is made up on
exactly the same plan as regards the shape of the filaments and amount and kind of
interfilamentar connectives and yet there is no septum dividing the blood channel

422

BULLETIN of the bureau of fisheries.

into two parts. It seems better to regard this structure as a partition which divides
the blood space of the filament into two blood channels because it is known to serve
this purpose in Area (i). In Pecten, where the circulation of the blood has been
changed from the original type, it no longer serves this function but remains as a
functionless membrane.

The outer surface of each filament is ciliated and three cells on each side have a
tuft of long cilia. (Fig. 5). The latter point outward and are usually regarded as
having a straining function, preventing food particles from entering the interlamellar
cavity with the water currents. If the usual interpretation be correct they have nothing
to do with the production of water currents.

The larger blood channels of the gill (fig. 3, d) show a structure similar to that of
the filaments. There is a one-layered epithelium on the outside which is ciliated for the
most part and contains numerous goblet cells (probably mucous secreting cells). Lining
the epithelium inside the vessel there is more or less of lacunar tissue which has retained
its primitive character. It contains scattered nuclei and its lacunar
nature is easily made out. I find no evidence of an endothelium,
which has been described by Bonnet (1) and Menegaux (9). The
vessels frequently contain bundles of muscle fibers and nerves which
run from the attached border to the free border of the gills. Their
distribution has not been studied, but figure 3 shows their position.

COURSE OF THE CIRCULATION IN THE GILLS.

Before giving the course of the circulation in the gills it will be
necessary to describe certain vessels which carry the blood to and
from these organs, and since the circulation is the same for the two
sides it will be necessary to describe it in but one. A very large
vessel, which we will call X, arising from the kidney, passes pos-
teriorly along the line of junction of the two gills as far as their
extremities. (Fig. 20, X, pi. l). It gives off numerous branches,
to the right and left, which pass through the interlamellar septa to the upper borders
of the reflexed lamellae. These lateral vessels open into one which runs along the
upper broder of the lamella. The latter which will be called vessel Y in further
descriptions, is a distributing vessel made necessary, it would seem, because the main
vessel from the kidney takes its origin near the middle of the gills, and hence no
blood could pass from it to their anterior portions except through some such arrange-
ment. Every other one of the larger vessels of the reflexed lamella (fig. 4, v), which
lie at the reentrant angles of the folds, connects directly with vessel Y. Every alternate
one (fig. 4, v') ends blindly at the upper border of the lamella. This was proved not
only by the study of sections but by injections as well. In the same way one-half of the
larger vessels of the direct lamella end blindly while the other half connect with an
efferent vessel which runs along its upper border carrying the blood back to the heart

Fig. 5. — Transverse sec-
tion of a filament highly
magnified, c. Cuticle
lining the blood space.

ANATOMY AND PHYSIOLOGY OF ATRINA RIGIDA.

423

after being aerated in the gills. The latter is a T-shaped vessel, one arm of which lies
in the suspensory membrane and carries blood from the anterior half of the gills, while
the other arm lies immediately below the vessel X and collects the blood from the poste-
rior portions of the gills. The two arms of the vessel flow together just anterior to the
kidney and form a rather wide tube disposed at right angles to them. (Fig. 9, a.)
This tube is perhaps an inch and a half in length and connects directly with the auricle.

From these connections it is clear that the blood enters the gills through the
reflexed lamellae and leaves them through the direct. When a starch mass was injected
into the vessel X the afferent vessels of this gill were injected and the course of the
blood was made out with certainty. The mass first distends vessel X and then passes
to Y, through the interlamellar septa, filling it from end to end. The mass now enters
the vessels of the gill which communicate with vessel Y and passes toward the gill’s
free margin. (See fig. 20, pi. L.) Half of the vessels of this reflexed lamella
are thus filled. Some of the mass flows across to the opposite lamella through the
interlamellar connections and fills half of its vessels. (Figs. 3 and 4, b.) Examination
shows that only those which end blindly above are filled with the mass, so that none
of the injection mass finds its way into the efferent vessels of the gills. By injecting
through the auricle, or the T-shaped vein which carries the blood from the gills, it is
possible to fill all the vessels of the gills not already filled by injecting from the kidney.
The mass first enters the direct lamellae and spreads across to the other. I have a
preparation in which the afferent vessels are injected with a black mass and the efferent
with a yellow one, which brings out the relationship between them quite clearly. It
is evident that provision is made for making the blood pass through the smaller vessels
of the gill before returning to the heart.

We may conclude from evidence obtained from the injections and anatomical
studies that the blood enters the gill through every alternate vessel of the reflexed
lamellae, from which part of it spreads to the right and left in the interfilamentar connec-
tives and filaments (fig. 4, i and /), finally finding its way into the neighboring vessels
of the same lamella. These vessels (fig. 4, v') end blindly above so that it must yet
pass across to the opposite lamella through the interlamellar connectives before finding
its way out of the gill to the heart. On the other hand part of the blood on entering
the gill passes at once across to the opposite lamella through the interlamellar connec-
tives into vessels which end blindly above. From these it spreads laterally, right
and left, in the interfilamentar connectives and filaments of this lamella and finally
into the neighboring vessels which open freely above into the vein which leads back to
the heart. The general course of the blood in the gill is therefore outward in the reflexed
lamella and the opposite in the direct, and the vessels are so connected that it must pass
through a capillary system in one lamella or the other before leaving the gills.

The relationship of vessels just described holds good for all parts of the gills, except
a narrow strip at their outer free margin. Here it is different and for completeness
must be briefly described. Here the transverse vessels (interlamellar connectives),
are very numerous and lie side by side. In the mid-line between the lamellae they

424

bulletin of the bureau of fisheries.

fuse and their cavities intercommunicate, forming a sort of irregular sinus. Here all
the vessels of the two lamellae seem to be in open communication, but the starch mass
was not forced into them sufficiently to show this. If one can rely upon sections, this
is true. Blood which does not find its way across to the direct lamella before reaching
the edge of the gill does so here by passing through one of the very numerous transverse
vessels which are present in this region. As has already been said, these intercommuni-
cate, and this may be an adaptation to take care of the extra amount of blood which
flows through the gills during muscular activity or when the heart beats rapidly from
any cause, supposing that the capillaries are not sufficient to accommodate it at such
times. Only a very small part of the blood passes around the edge of the gill. As
has been stated already, the filaments disappear at the edge of the gill, but it is possible
to trace vessels to the edge where they communicate with irregular spaces which pass
around to the opposite lamella.

It is clear that the blood does not pass, as a whole, down one lamella and up the
other, as is the case in Pecten tenuico status , as described by Drew (2). All the vessels of
the outer lamella of this form are afferent, and all of those of the inner lamella are
efferent. He found none ending blindly and no cross connections. On the other hand,
Johnstone (6), studying Cardium edrde, found that half of the vessels of each lamella
are afferent and half are efferent. He implies that the efferent vessels of each lamella
open separately into the main efferent vein, but he does not make this plain, and his
figures 24 and 30 are inconsistent. If we imagine the efferent vessels of the outer lamella
as ending blindly above, and give them many cross connections with those of the oppo-
site lamella, we have practically the arrangement found in Atrina, although the gills
of the two forms differ considerably in other respects. As regards circulation the gill
of Atrina is therefore intermediate between those of Cardium and Pecten, but is more
nearly like CardiumA

RESPIRATORY CURRENT.

The respiratory current in Atrina is remarkably strong. When specimens are as
much as 6 inches below the surface a very considerable agitation of the water directly
above them is perceptible when the respiratory current is running full force. In fact,
the water fairly boils. The mantle, being open, may admit water at any point ventral
to the inter mantle septum and it is expelled dorsal to this structure. While the respira-
tory current is flowing the edges of the mantle are brought quite close together, so that
objects of any considerable size are prevented from entering the mantle chamber. It
was found difficult to get admission even for powdered carmine. The sensory tentacles
detect solid objects in the water and the mantle closes, preventing their entrance. When
one shell is partially removed and the mantle lobe folded back the respiratory current
within the mantle chamber can sometimes be seen. Powdered carmine shows strong

a Bonnet describes a different circulation for the gill of Pinna nobilis , a form so closely related to Atrina that one would expect
to find no fundamental differences in the circulation. Menegaux finds the work of Bonnet incorrect. His description of the
anatomy of the gill for Pinna agrees very closely with mine for Atrina. but*he gives a different description of the course -of the
circulation through it. I am inclined to think they are the same.

ANATOMY AND PHYSIOLOGY OF ATRINA RIGIDA.

425

currents sweeping anteriorly in the ventral part of the mantle chamber, turning dorsally
between and over the outer surface of the gills. The inflow of the water seems to be
due in part to the action of the fine cilia of the inner surface of the mantle, but the gills,
much of whose inner and outer surfaces are ciliated, are evidently the seat of the great
pulling force.

FOOD-BEARING CURRENTS.

The respiratory current entering the mantle chamber carries with it many small
objects in suspension, including minute living organisms. These are not allowed to pass
through the gills, but are filtered out and passed in slow moving currents toward the
mouth. These food-bearing currents are easily followed when powdered carmine, sus-
pended in water, is dropped upon the gills. The particles of carmine are seen to move
outward to the free border of the gill, where they enter the longitudinal groove in its
edge and pass toward the anterior, finally reaching the palps, between which they con-
tinue to the mouth. These respiratory currents and food-bearing currents have long
been known, and they seem to be much the same in all lamellibranchs. It was thought
until recently that so long as water was flowing into the mantle chamber the lamelli-
branch had no choice but to receive the food, strained from it, into its digestive tract.
In 1900 J. T. Kellogg (7) showed that when food was not desired it could be turned aside
in the palps and deposited by them into backward-moving currents in the mantle,
through which it was carried directly or indirectly to the exterior. Stenta (14), working
independently upon many forms, including Pinna, came to the same conclusions. In
Atrina I found the food-bearing currents turned aside at about the middle point of the
palps at the anterior end of the corrugated portion. Here it moves outward to the edge
of the palps and then posteriorly to their tips, where it leaves them to enter the ciliated
canal of the mantle, which transports it to the exterior. Whether lamellibranchs can
exercise choice in their food, accepting only the part which is desirable, is not known.
C. Grave (3) compared the contents of the digestive tract of oysters with diatoms found
in the water above their beds and came to the conclusion that they have the ability to
choose. J. L. Kellogg read a paper before the American Society of Zoologists in Decem-
ber, 1909, in which he stated that it is not the nature of the food but the quantity of it
which causes lamellibranchs at times to reject it. When great quantities of food
material are carried to the palps by the gills they reject it. In this case it passes out-
ward in the grooves of the corrugated portion of the palps to their outer borders and then
posteriorly to their tips. It then enters the backward-moving currents in the mantle
chamber and is expelled.

CIRCULATORY SYSTEM.

In order to get a good injection of the blood vessels it was necessary to narcotize
the specimens. Otherwise they would contract to such an extent as to make the rela-
tion of the parts unintelligible. This was done by placing them in a large pan of sea
water and adding alcohol slowly until dead, which required from six to eight hours. By
this means they remained expanded and the vessels were relaxed sufficiently to allow
easy penetration of the injecting fluid.

426

bulletin of the bureau of fisheries.

ARTERIAL SYSTEM.

The arterial system is not bilaterally symmetrical, so that a description of the arte-
ries of each side will be necessary.

The heart lies in the pericardium just anterior to the adductor muscle and mantle
gland. It consists of a heavy walled ventricle and two thin walled auricles. (Fig. 17, h,
pi. xlix.) The latter are elongated in the direction of the longitudinal axis of the body
and are attached at one extremity to the tissue covering the retractor muscle and at the
other to the adductor. They receive the blood from the gills through a short tube
which lies external to the retractor muscle. (Fig. 17, t, pi. xlix, and text fig. 9, a.)

The ventricle is a saddle-shaped structure into which the auricles open on either
side. It gives off an anterior and a posterior aorta. The latter soon gives rise to a large
branch which passes dorsally to the right of the rectum and enters the mantle. This
artery divides into two equal branches at the posterior dorsal angle of the mantle, one
branch going to the right mantle lobe, while the other goes to the left.

The arteries of the left mantle are represented in figure 17, plate xlix, the right
mantle lobe having been removed and its artery being therefore shown cut off. The
mantle artery branches very profusely. It will be noted that there are two parallel
arteries connected by numerous anastomoses. The outer and smaller of the two is dis-
tributed to the edge of the mantle, the other branches mostly in the opposite direction,
and supplies the greater part of the mantle. This posterior mantle artery meets and
joins with a similar one from the anterior end of the body.

The posterior aorta gives rise to a second branch, which is distributed to the rectum
and mantle gland, then, bending abruptly ventrally, it enters the adductor muscle. A
small branch continues over the anterior face of the adductor and goes to the region of
the visceral ganglia and kidneys. (Fig. 18, pi. xlix.)

The anterior aorta is much the larger of the two. On the right side (fig. 17, pi. xlix)
it gives rise to five branches which go to the reproductive organ and liver. Three
small branches go to the dorsal part of the mantle where they spread anteriorly and
posteriorly in the midline. At the anterior end of the visceral mass the aorta gives
off a branch which passes forward over the anterior retractor muscle. Three arteries
arise from this branch; one to the outer palps, one to the middorsal line of the mantle,
and one to the anterior adductor muscle. It then passes over the anterior adductor
and at the extreme anterior end of the body divides into two equal branches, one of
which goes to the right mantle lobe and the other to the left. These two branches
join with the similar mantle arteries which arise from the posterior aorta.

The aorta after giving off the artery, which has just been described as passing
above the anterior retractor muscle, bends ventrally and divides into a number of arteries
which are distributed to the inner palps and byssal apparatus and foot. Those which
go to the bvssus are paired, right and left; but those to the left side are not represented
in the figure.

The arteries given off from the aorta on the left side of the body are represented in
figure 18, plate xlix, and are three in number. All three are distributed to the digestive

ANATOMY AND PHYSIOLOGY OF ATRINA RIGIDA.

427

tract, to some extent, as well as to the reproductive organ and liver. The middle one
lies deep within the visceral mass and follows closely the coils of the intestine. The
most anterior one, besides giving branches to the stomach and liver, gives one to the
byssal apparatus and posterior retractor muscles of the foot (fig. 18, a, pi. xlix). Other
arteries shown in this figure have already been described as belonging to the right side
of the body. The main branches of the arteries are constant in number and portion,
but the smaller ones are not so constant. There is so much variation in these as to be
confusing to one who is studying them. The figures were drawn after dissecting several
specimens, so that they may fairly be considered typical.

VENOUS SYSTEM.

The venous system, unlike the arterial, seems to be absolutely symmetrical, so
that a description of one side will suffice for both. The venous blood enters the kidney
from the visceral mass through a large vein which runs diagonally over the surface
of the posterior retractor muscle of the foot. This vein brings blood from nearly all
parts of the body, including the foot, byssus, liver, reproductive organ, and digestive
tract. (Fig. 19, v, pi. xlix.) There is no venous sinus below the pericardium into
which the blood collects previous to entering the kidney. The blood enters the kidney,
as stated above, through a large vessel which breaks up into a closed capillary system.
After bathing the glandular cells of the kidney the blood is collected into a large vein
which transports it to the gills to be aerated.

The blood from the adductor muscle, and probably also the mantle gland, drains
into a sinus located on the ventral surface of the adductor. This sinus communicates
with the vein to the gills on each side just as it emerges from the kidney, and hence
the blood from the adductor and mantle gland does not enter the kidney, but goes
directly to the gills. Since this sinus communicates with both sides it is possible to
inject the veins of both sides from one point.

Besides the sinus just mentioned there is another at the base of the foot. Those
organs which are extended by blood pressure therefore have sinuses in their immediate
vicinity.

After traversing the gills the blood is returned to the heart by two vessels, one of
which lies in the suspensory membrane and carries the blood from the anterior half of
the gills, the other bears the same relation to the posterior half of the gills as the first
to their anterior portion. These two vessels flow together to form a single short wide
tube which runs at right angles to them and communicates with the auricle. This
tube lies just anterior to the adductor muscle and runs over the outer surface of the
retractor muscle. (Text fig. 9, and fig. 16, pi. xlviii.) Just before entering the auricle
it receives a vein from the mantle. The latter is formed by the union of two mantle
veins, one from their anterior and the other from their posterior portions.®

a A number of small vessels from the palps enter the distributing vessel of the gills. The direction of the flow of the blood
in these vessels was not determined, but it is probably toward the gills. They may therefore be considered as part of the venous
system.

428

BULLETIN OF THE BUREAU OF FISHERIES.

It will be noted that the blood which goes to the mantle passes through one capillary
system before returning to the heart, that to the adductor and mantle gland passes
through two, while that to the body proper passes through three, viz, those of the body,
kidney, and gill. In this respect as well as in general plan the circulation seems to be
similar in many lamellibranchs. The walls of the veins in general are not so well
defined as those of the arteries. When a starch mass which had been strained through
fine bolting cloth was injected into the veins, it soon spread out among the tissues, show-
ing that the blood is not confined in a closed system of vessels. The arteries, however,
divide into extremely small branches, so that it was impossible to force the injection
mass to their ends.

ADDUCTOR MUSCLES.

There are two adductor muscles, the anterior of which is small and practically use-
less so far as could be made out. The posterior adductor is lar>ge and powerful and is
situated near the middle of the shell. It is composed of two distinct kinds of fibers as
indicated by a difference in color. The ventral two-thirds is darker than the dorsal
one-third. No attempt was made to distinguish physiological differences in these parts,
but various opinions have been given. Von Jhering (15) experimented upon Pecten to
determine the difference in function of the two kinds of fibers. He cut the dark portion
and found that the remaining white portion contracted only very slowly, but it pre-
vented the valves from opening widely under the influence of the hinge ligament. He
next cut the white portion of another specimen and found that the remaining dark por-
tion was capable of very rapid contraction, but it could not hold the valves closed for
any considerable time. It also allowed the valves to gape widely. He therefore con-
cluded that it is the function of the white portion to keep the valves from gaping widely
and to hold them closed for a long time when occasion demands. The dark portion,
according to his view, is the real muscle to which the contractions are due. J. Iv. Kel-
logg (7) holds the opposite opinion, that it is the white portion which is contractile, and
that the dark part is for the purpose of keeping the valves tightly closed.

In Atrina the mantle muscles are white and are capable of rapid contraction, while
the anterior adductor and foot retractor muscles, which are also white, scarcely con-
tract at all. The white muscle fibers of lamellibranchs may therefore be quick or slug-
gish in their contractions. Von Jhering is the only investigator who has isolated the
two kinds of fibers to test them, and his results seem conclusive, although Pelseneer (n)
and Kellogg have opposed his view.

RETRACTOR MUSCLES OF THE FOOT.

There are two pairs of foot retractors, one posterior and the other anterior. The
latter is so situated that the foot would be extended by its contraction rather than
retracted, but it is customary to call this pair of muscles retractors. As a matter of
fact none of these muscles has any considerable power of contraction. Their function
seems rather to be to support the body. They suspend it in the manner of a hammock.

ANATOMY AND PHYSIOLOGY OF ATRINA RIGIDA. 429

(Fig. 19, pi. xlix.) The anterior retractors are cylindrical and composed of white
fibers. At one end they are inserted into the anterior surface of the foot, while at the
other they are attached to the shell just posterior to the anterior adductor muscle. (Fig.
19, ar, pi. xlix.) The posterior retractor muscles appear large in the drawings, being
attached at one end to the base of the foot and at the other to the shell just anterior to
the posterior adductor muscle. (Fig. 19 pr, pi. xlix.) This structure in reality con-
sists of two parts, the byssal apparatus and the muscle proper. These retractor muscles
have become very much reduced. They no longer serve to retract the foot, but have
taken on a new function, that of supporting the byssus.

VISCERAL MASS.

The main body of the visceral mass is approximately cone shaped, with the apex at
the anterior end. It is slightly flattened dorso-ventrally and at the posterior end there
is a slender horn which projects back below the pericardium between the posterior
retractor muscles. Its hindermost extremity rests upon the adductor muscle. (Fig.
18, pi. xlix, and fig. 9, m.) The visceral mass includes the digestive and reproductive
organs. The liver, which surrounds the stomach, fills the anterior part. The repro-
ductive organs fill the remainder of the space not occupied by the coils of the intestine.
The sexes are separate and are easily distinguished by the color of the reproductive organ,
which shows through the thin body wall. The testis is white, as shown in figure 16,
plate xlviii, while the ovary is orange red. The main duct, which carries the repro-
ductive elements to the exterior, opens into the kidney very near the renal aperture.
(Fig. 6, g.) Fertilization of the eggs takes place after they are extruded into the water.

FOOT AND BYSSUS.

The foot is cone shaped and is attached to the anterior end of the visceral mass.
At its base a large opening, from which the byssus protrudes, is to be found. (Fig. 16,
pi. xlviii.) From this point a groove extends along the ventral surface of the foot to a
point near its tip. (Fig. 15, g.) The byssal gland is situated in the floor of this groove
and is continued back of the foot into the posterior retractor muscles. The foot can
be protruded, and it is probably of service in attaching the byssus.

KIDNEY.

The kidneys are two in number, and each consists of a glandular and a nonglandular
portion. They lie between the gills on the ventral side of the body, just anterior to the
abductor muscle. They hang down into the central suprabranchial chamber as two
dark colored bags and are very conspicuous organs, requiring no dissection to expose
them. (Fig. 20, K, pi. l.) Each is in open communication with the pericardial
chamber above and each opens below into the suprabranchial chamber by a large tube,
which ends at the summit of a papilla. The glandular portion forms the prominent sac
mentioned above and lies about midway between the two extremities of the kidney.
For convenience of description the kidney may be divided into three portions: First, a

430

BULLETIN OE THE BUREAU OF FISHERIES.

tube (a, fig. 6) which opens into the pericardium; second, a short tube ( b ) which opens
to the exterior; third, a central pouch (c) into which the tubes a and b open at their inner
ends. This central pouch is large and irregular in shape. One branch of it extends
upward over the posterior retractor of the foot and ends beneath the pericardium. (Tig.
6, e.) This portion of the kidney is probably homologous with a kidney-like organ
which Grobben (5) found in a number of lamellibranchs extending as a fold into the peri-
cardium and connected below with a large sinus, which he believed to belong to the
kidney. In Atrina it is plainly a branch of the main kidney.

The glandular portion (fig. 6, h) is located at the posterior and outer end of the main
pouch. It is quite extensive and is colored dark brown on account of the reddish brown
excretory material which is inclosed by its cells. All other parts of the kidney appear
colorless and thin walled.

Fig. 6. — Drawing of the kidney in position, showing three well-marked parts, a tube (a) opening into the
pericardium, a tube (6) opening to the exterior, and a large central pouch ( c ) into which tubes a and b
open at their inner ends; e represents a prolongation of pouch c which extends upward beneath the peri-
cardium; g, the genital duct; k , the glandular portion of the kidney; p, the pericardium.

It will be noticed that this kidney differs considerably from the usual type, which
is typically a coiled tube. In the form under consideration it may once have been a
true coiled pouch. Its transformation may have come about by the fusion of the two
branches of the central loop to form the single large pouch.

While working with living specimens I frequently saw quantities of vellowish-brown
material expelled from the kidneys. When examined under the miscroscope this
material proved to consist of very numerous vacuolated cell-like bodies, which were
filled with yellowish-brown or reddish-brown globules of excretory matter. Each
excreted body had a tuft of extremely long cilia which were still active. (Fig. 7.) After
collecting and fixing some of this excreted matter I stained it with iron-alum hsema-
toxylin to see if there were nuclei present. None were found and I believe that none
are thrown off. Paraffin sections of the glandular portions of the kidney show the
epithelial cells to be greatly vacuolated and filled with this excretory matter. (Fig. 8.)
The vacuole is located in the outer end of the cell and there is very little protoplasm

ANATOMY AND PHYSIOLOGY OF ATRINA RIGIDA. 43 1

surrounding it. The nucleus is seen in the basal end of the cell and is surrounded by
dense protoplasm. Certain cells show a constriction below the vacuole, as if they were
in process of being divided. Other cells show this process farther advanced, and appear
as if they were drawn out by some force which was stretching them into two. The
nuclei in these cells
are to be seen in the
basal half, and it ap-
pears also that very
little cytoplasm is
thrown off with the
vacuole. This
method of excretion,
although uncommon,
is not especially
wasteful, as would
appear from the state-
ments of investigators
who have written
upon this subject and
maintained that the
entire cells are ex-
creted in the mollusks studied by them. Of course this may take place in some;
but excretion in Atrina is not of that wasteful character.

DIGESTIVE TRACT.

The stomach is a large asymetrical pouch which adheres closely to the dorsal wall
of the visceral mass. On the left side it is attached to the ventral wall by a strand of

muscle tissue. The ducts of the liver
open into it at two points, one on the
right and one on the left. (Fig. 9, d.)
A part of the epithelium lining the roof
of the stomach is differentiated as a
conspicuous gland which forms a prom-
inent ridge within the cavity of the
stomach. The anterior end of the crys-
talline style adheres closely to this gland.

The intestine originates at the pos-
terior end of the stomach and passes to
the extreme posterior end of the visceral
mass, where it bends sharply to the right and passes anteriorly as far as the stomach. It
then makes a large loop and again passes posteriorly, traverses the ventricle and mantle
gland, to end behind the adductor muscle (Fig. 9.)

The part of the intestine nearest the stomach possesses a feebly developed typhlosole,
while the remainder has it very strongly developed. A large crystalline style lies in

Fig. 7. — Bodies excreted from the kidney, formed by the pinching off of the vacuolated tips of
the cells. Note the tuft of long cilia on each and the concretions of waste material within
the vacuole.

432

BULLETIN OF THE BUREAU OF FISHERIES.

the part of the intestine which has the typhlosole feebly developed. This crystalline
body is largest near the stomach and tapers gradually to a point and ends just beyond
the first bend of the intestine, where the typhlosole becomes prominent. The latter
structure is much swollen and gelatinous at this point, so that it almost obliterates the
cavity of the intestine.

Several theories have been advanced to explain the nature of the crystalline style.
Mytra (io) seems to have shown pretty conclusively that it contains an enzyme which
will digest starch. He thinks it is a secretion from the liver. Pelseneer (i i) has held for
a long time that its function is that of protection. He thinks it forms a protective
coat for the intestine and surrounds rough particles of sand and diatom shells which
might otherwise injure the delicate tissues. I find a structureless coat or cuticle of

Fig. 9. — Drawing of the digestive system in position, g, Mantle gland; m, visceral mass; o, mouth;
s, stomach; d, opening of liver ducts into stomach; i, intestine; r, rectum.

some kind lining a considerable part of the wall of the intestine. This may be formed
from the crystalline style and may serve to protect the epithelial lining of the intestine.

NERVOUS SYSTEM.

The central nervous system consists of three pairs of ganglia which are connected
by nerve tracts, or commissures, in the usual way. One member of each pair of ganglia
is situated on the right side of the body and the other directly opposite it on the left.
Bach ganglion supplies nei ves to tissues situated on its own side of the body only, and
since those of the right and left are alike in number and distribution they will be described
as coming off in pairs. The pedal ganglia are fused more or less to' form a single mass,
but the line of separation is plainly discernible. (Big- 10, pg.) They are situated
at the base of the foot and they give off three pairs of nerves posteriorly which are dis-
tributed to the byssal apparatus and retractor muscles of the foot. They also give rise
to one pair of nerves from their lower anterior surfaces, which penetrate the foot.

ANATOMY AND PHYSIOLOGY OF ATRINA RIGIDA. 433

The cerebral ganglia are situated wide apart, there being one on each side of the
esophagus. They are connected by a nerve ring which passes over the esophagus. (Fig.
10 and 12, cc .) They give off a number of nerves, usually seven pairs, to the palps. A
very large nerve leaves the anterior end of the ganglion and passes parallel to the
cerebral connective for a short distance
and then bends outward and enters the
mantle. Just before it enters the mantle
it gives off a branch, which continues
forward for a short distance above the
anterior retractor muscle of the foot.

This branch then bends outward and
ventrally, penetrates the tissue of the
retractor muscle, from which it finally
emerges and enters the anterior adductor.

(Fig. i2.) The mantle nerve having
entered the mantle divides into a number
of branches, all of which unite with the
circumpallial nerve, to be described later.

Each cerebral ganglion communicates
with the corresponding pedal ganglion by
a short, thick connective. A complete
nerve ring is thus formed around the
esophagus. (Fig. 10.)

The visceral ganglia are situated on
the ventral face of the adductor, just
posterior to the kidney. They lie near
together and are connected by a very thick commissure which contains many
nerve cells. (Figs, n and 12, vg.) A large cerebro- visceral connective passes

through the kidney and visceral mass between the cerebral and visceral ganglia.

(Fig. 12, c.) The visceral ganglia give off four pairs of nerves to the posterior,

which pass over the ventral surface of the adduc-

tor. (Fig. 19, 1, 3, 3, and 4.) Three of these
finally bend outward and enter the mantle. Their
course in the mantle may be seen in figure 12,1,2, and
3. Most of the branches of these nerves unite with
the circumpallial nerve, but a few from the most
anterior of the three lose themselves in the tissue
of the mantle. The fourth pair of nerves, described
above as lying on the ventral surface of the adduc-
tor, does not reach the mantle, but passes near
the rectum and enters the muscles of the mantle
gland. Judging from their close connection with the
muscles of this organ, one is led to believe that they are distributed to the muscles only.
Another pair of nerves which arises from the visceral connectives (fig. 11,5) passes on
the surface of the adductor in the opposite direction from those just described and enters
the tissue of the mantle gland. These nerves are most likely distributed to the glandular

48299° — Bull. 29 — 11 28

Fig. 11. — Drawing of the visceral ganglia, r, 2,
and 3, nerves to the mantle; 4 and 5, to
mantle gland; 6, to adductor; 7, to gills;
S, to kidneys; 9, the cerebro visceral con-
nective.

connectives, eg, Cerebral ganglion; pg, pedal ganglia; cv,
cerebro visceral connective; cc, cerebral connective; in, nerve
to mantle and anterior adductor; 1, 2, 3, 4, 5, and 6, nerves to
the palps.

434

bulletin of the bureau of fisheries.

portion of this structure, since they do not seem to be closely associated with muscles.
The other nerves which belong to the visceral ganglia are the following: A pair of large
nerves which penetrate the adductor muscles (fig. n, 6), a large pair to the posterior
portions of the gills (fig. n, 7), and a pair of very small nerves (fig. n, 8), which are
distributed to the kidneys. I have been unable to find the nerves to the anterior part
of the gills. These nerves, however, arise from the visceral ganglia, as can be proven by
experimental methods. If the gills are isolated from the cerebral and pedal ganglia by
cutting all possible connectives, they will still contract when the posterior part of the
mantle is stimulated. The anterior part of the gills will contract under these conditions,
even after the large nerve to the posterior part of these organs has been cut. It is there-
fore evident that the nerve supply of the gills comes entirely from the visceral ganglia.

The circumpallial nerve lies near the edge of the mantle, to which it gives off numer-
ous small nerves. (Fig. 12, cp.) It runs entirely around the mantle, passing across the
mid line at either end, and thus forms a complete ring. Although it seems to contain

Fig. 12. — Drawing to show distribution of mantle nerves, eg, Cerebral ganglion; pg, pedal ganglion; cc,
cerebral connective; c, cerebro visceral connective, cp, circumpallial connective; 1, 2, and 3, mantle
nerves from the visceral ganglion; 4, mantle nerves from the cerebral ganglion; ot, otocyst.

many nuclei it has no motor nerve cells. If the nerves from the cerebral and visceral
ganglia are cut the mantle is paralyzed. The neuclei which might be mistaken for nerve
cells probably belong to the nerve sheath.

A number of experiments were performed to determine which parts of the body are
supplied with nerves from each ganglion. The experimental and anatomical evidence
agree and there seems to be little if any overlapping. Each ganglion seems to supply its
own definite regions of the body. The visceral ganglion controls the posterior part of
the mantle, posterior adductor muscle, gills, mantle gland, and kidneys. The cerebral
ganglia control the anterior part of the mantle, the palps, anterior adductor, and anterior
retractor muscles. The cerebral and pedal ganglia together control the foot, posterior
retractor muscle, and byssus. The nerves to the viscera and heart were not discovered.
A more complete account of the experimental study of the nervous system of this form
is given in a paper published in the Johns Hopkins University circular for June, 1909 (4).
The most interesting feature of this work was the discovery of reflexes. For example,

ANATOMY AND PHYSIOLOGY OF ATRINA RIGIDA.

435

when the mantle is stimulated gently opposite the anterior end of the gills, the anterior
part of the gills contract, while the posterior part of these organs remains quiet. A
stronger stimulus causes the whole of the gills, as well as other parts, to contract.

SENSE ORGANS

OTOCYSTS.

The otocyst in Atrina is located very near the tip of the foot and has therefore a
very unusual position. (Fig. 12, ol.) It varies greatly in size in different specimens
and may be a degenerating organ. In some specimens it was found to be an extremely

Fig. 13. — Drawing of a transverse section of one lobe of the otocyst,
outlined with a camera lucida. c. Ciliated tube connecting the
otocyst with the exterior; e, ciliated epithelium forming the wall
of the otocyst; o, otolith showing concentric structure.

Fig. 14. — Reconstruction of the
compound otocyst from a
series of sections.

small sac lined by ciliated epithelium containing no otolith. In others it is a large
lobed structure with an otolith in each lobe. The otoliths (fig. 13, o) show a concentric
structure. Figure 14 represents a reconstruction of the otocyst from a series of sections,
and shows that in this specimen there were two or three otocysts in place of one, the
usual number. There are three ciliated canals leading in toward the otocysts from the
outside and although they could not be traced into the otocysts they came so near
that there is scarcely an}' doubt but that they are the tubes formed by the invagination
of the ectoderm, which gave rise to the otocysts. (Figs. 13 and 15, c .) The evidence
indicates therefore that there are three otocysts in this specimen formed by independent

436

BULLETIN OF THE BUREAU OF FISHERIES.

invaginations of the ectoderm. Some of the numerous lobes seen in figure 14 were
formed by division of the original otocysts. Some of the lobes are completely separate
from the rest while the cavities of others communicate with those of their neighbors
If there is a nerve connected with the otocyst, it was not discovered.

OSPHRADIUM.

The osphradimn consists of a small patch of sensory epithelium situated directly
ventral to the visceral ganglion at the origin of the branchial nerve. (Fig. 20, 0, pi. l.)

It is large enough to be seen with-
out magnification and appears to be
colorless. When examined under the
microscope, however, its cells are seen
to contain a yellow pigment. Nerve
fibers are distributed to the osphra-
dium from a ganglionic mass which
surrounds the base of the branchial
nerve. This nervous tissue appears
to be a part of the visceral ganglion,
but Pelseneer insists that the osphra-
dium receives its nerve supply from
the cerebro-visceral commissure and
hence from the cerebral ganglion. I
have no preparations to show that
this is the case. This sense organ
is said to be used for testing the
purity of the water, whatever that
may mean.

SUMMARY.

1. The arterial system of the
two sides is not symmetrical, as
may be readily seen by a com-
parison of figures 17 and 18, which
represent the arteries of the right
and left sides, respectively.

2. The venous system lacks the “sinus venosus’’ which is commonly present in
lamellibranchs and which receives the blood from all parts of the body previous to
entering the kidney. This sinus or a substitute for it is a necessary part of the mechanism
described by Menegaux for extruding the foot and other organs whose movement is due
to blood pressure.

3. The blood in traversing the kidney passes through a closed capillary system.

4. The blood which enters the gills must pass through a capillary system before
emerging again.

Fig. 15. — Drawing of transverse section of the foot showing the position
of the otocyst. (Outlined with camera lucida.) b, Byssal gland; g,
ventral groove in the foot; m , circular and transverse and longitudinal
muscles; n, nerves; o, otocyst; c, ciliated tube which has given rise to
the otocyst by invagination f rom the ectoderm; p my undifferentiated
mesoblast.

ANATOMY AND PHYSIOLOGY OF ATRINA RIGIDA.

437

5. There is no pallial line but the mantle is attached to the shell at a single point
just ventral to the adductor muscle. As a consequence the mantle can be withdrawn
a considerable distance from the edge of the shell. After being contracted the mantle
again reaches the edge by creeping outward upon the shell.

6. The spines on the outer surface of the shell are formed by little tongues of the
mantle which creep out into them during their growth period.

7. The mantle gland which Menegaux calls the “appendice” is probably a “swab”
for keeping the mantle free from dirt.

8. The kidney excretes vacuoles containing quantities of concretions, but little
protoplasm and no nuclei are thrown off.

9. Each ganglion supplies a definite region of the body and there is little over-
lapping. Reflex arcs were shown to exist.

10. The otocyst is located in the end of the foot far from the pedal ganglion and is a
variable structure, sometimes consisting of as many as eight lobes and sometimes of
only one. In one instance three separate ciliated tubes connecting them with the out-
side were discovered. This indicates that they have arisen from three separate invagi-
nations of the ectoderm. This is the first instance of this sort found in lamellibranchs
above the Protobranchia.

BIBLIOGRAPHY.

1. Bonnet, R.

Der Bau und die Circulationsverhaltnisse der Acephalenkieme. Morphologisches Jahrbuch, bd. 3,
1877, p. 283-322.

2. Drew, G. A.

The habits, anatomy, and embryology of the giant scallop (Pecten tenuicostatus, Mighels). Uni-
versity of Maine Studies, no. 6, September, 1906, 71 p., 17 pi.

3. Grave, C.

Investigations for the promotion of the oyster industry of North Carolina. Report U. S. Fish
Commission 1903, p. 247-341, pi. i-x, 1 map, 1905.

4. Grave, B.

Pinna seminuda. John Hopkins University Circular No. 6, June, 1909, p. 46-51.

5. Grobben, C.

Zur kenntniss der anatomie und morphologie von Meleagrina sowie der Aviculidae. Im Allege-
meinen Denkschrift der k. Akademie der Wissenschaft, Mathematisch-Naturwissenschaftliche
Klasse, bd. 69, 1901, p. 487-496.

6. Johnstone, J.

On the structure and life history of the common cockle, with an appendix on the Lancashire
cockle fisheries. Proceedings and Transactions of the Liverpool Biological Society, vol. 14,1 900,
p. 178-261, pi. 1— vi and map.

7. Kellogg, J. L.

A contribution to our knowledge of the morphology of the lamellibranchiate mollusks. Bulletin
U. S. Fish Commission, vol. 10, 1890, p. 389-436, pi. lxxix-xciv, text fig. 1-3.

The ciliary mechanism in the branchial chamber of the Pelecypoda. Science, n. s., vol xi, 1900,
no. 266, p. 172-173.

438

bulletin of the bureau of FISHERIES.

8. Lacaze-Duthiers.

Memoire sur le developpement des branchies des mollusques acephales lamellibranches. Annales
des Sciences Naturelles, Zoologie, ser. 4, t. 5, 1856.

9. MenEgaux, A.

Recherches sur la circulation dans les lamellibranches marines. Besanfon, 1890, 291 p., 56 fig.

10. Mitra, S. B.

The crystalline style of Lamellibranchia. Quarterly Journal of Microscopical Science, vol. 44,
1901, p. 591-602.

11. PELSENEER, P.

Contribution letude des lamellibranches. Archives de Biologie, t. xi, 1891, p. 147-312, 2 fig.,
pi. 6-23.

12. Peck, R. H.

The minute structure of the gills of lamellibranch Mollusca. Quarterly Journal of Microscopical
Science, vol. xvn, 1877, p. 43-66, pi. iv-vii.

13. Rice, E. L.

Fusion of filaments in the lamellibranch gill. Biological Bulletin, vol. 11, 1900, no. 2, p. 71-80,
text fig. 1-8.

14. Stenta, M.

Zur Kenntniss der Stromungen im Mantelraum der Lamellibranchiaten. Arbeiten aus den
Zoologischen Institut der Wien, bd. 14, 1903, p. 211-240, 2 fig., taf.

15. Von Jhering, H.

Ueber Anomia. Zeitschrift fur wissenschaftliche Zoologie, bd. 30, sup. hft. 1, p. 13-27, pi 11.

EXPLANATION OF PLATES.

PRATE xlviii.

Fig. 16. Drawing of a specimen natural size to show the relative position and appearance of the vari-
ous organs. One shell valve, one mantle lobe, and the posterior half of the gills of one side have been
removed. P A, posterior adductor; A, anterior adductor; C, posterior retractor of the foot; P, palps;
G, gill; F, foot; B, byssus; M, mantle gland; R, rectum; K, the portion of the kidney which commu-
nicates with the pericardium; T, testis; D, ciliated canal of the mantle which carries debris from the
mantle chamber.

PLATE XLIX.

Fig. 17. Drawing of the arteries of the right side of the body and of the left mantle lobe, the shell,
right mantle lobe, gills, and kidneyshaving been removed, h, heart; t, tube which carries the blood from
the gills to the auricle, here shown cut off just below the auricle; v, anterior aorta; p, posterior aorta;
m, mantle artery; g, cerebral and pedal ganglia; op, and ip, arteries to the outer and inner palps,
respectively.

Fig. 18. Drawing of the arteries of the left side of the body, the shell, left mantle, gills, posterior
retractor muscles of the foot and kidneys having been removed; m, visceral mass; o, artery to the
retractor muscles which have been removed. The distribution of the other arteries is easily made out
in the drawing. Only the main trunk of the mantle arteries is shown here, but they are similar to those
represented in figure 17.

Fig. 19. Drawing of the principal veins of the right side of the body, the shell, right mantle lobe, and
gills having been removed, pr, posterior retractor muscle of the foot; ar, anterior retractor of the foot; v,
the large venous trunk which enters the kidney and breaks up into capillarise; 1,2, and 3, veins from
the foot and byssal apparatus, they receive blood from a large sinus which lies just at the base of the
foot; k, the vein which gathers the blood from the kidney and carries it to the gills. It is here shown
cut off at the point where it entered the gills.

BULLETIN OF THE BUREAU OF FISHERIES.

439

PLATE L.

Fig. 20. Semidiagrammatic drawing of a specimen, ventral side up, to show the veins which enter
the kidneys and those which emerge from them. The shell, part of theleft mantle, and the gills of the
left side have been removed. One kidney is cut open to show that the large vein upon entering the
kidney breaks up into capillaries. F, foot; G, gill; G/, the upper border of the reflexed lamella of the
gill; K, kidney; O, osphradium; i, 2, and 3, mantle nerves from the visceral ganglion which lies upon
the adductor muscle at the posterior end of the kidneys; 4, nerve to mantle gland; V, vein entering
the kidney (the same as the vessel labeled V in fig. 19); x, the vessel which carries the blood from the
kidney to the gills; y, the vessel which receives the blood from vessel x and distributes it to all parts
of the gill.

Plate XLYIII.

Fig. 16.

_OLa

Bull. U. S. B. F., 1909.

Plate XUX.

Fig. 17.

Fig. 18.

Fig. 19.

Bull. U. S. B. F., 1909

Platk I

Fig. 20.

GENERAL INDEX.

Page.

Acasta spongites japonica 80

alascanus, Leucichthys 16

Alaska whitefish 38

albus, Coregonus 37

Allosomus 31

Alpheus, molting of hammer claw 207

American lobster ( see Lobster) 149-408

anatifera, Lepas 7°

Anatomy and physiology of Atrina rigida (see Atrina

rigida) 409-430

anserifera, Lepas 7°

apertus, Balanus rostratus 74

Areoscalpellum 62

Arctic lake herring 16

arcturus, Leucichthys harengus 8

artedi, Leucichthys 17

Atrina rigida, adductor muscles 428

anatomy and physiology 409-439

arterial system 426

burrowing 414

circulation in gills 422

circulatory system 425

digestive tract 431

food-bearing currents 425

foot and byssus 429

gills 418

kidney 429

labial palps 417

mantle 413

mantle gland 416

nervous system 432

osphradium 436

otocysts 435

regeneration and growth of shell 414

respiratory current 424

retractor muscles of the foot 428

sense organs 435

shell 412

structure of filaments 421

venous system 427

visceral mass 429

auritum, Conchoderma 70

Balanus callistoderma 78

cariosus 76

crenatus 75

evermanni 76

hoekianus 77

rostratus 73

rostratus apertus 74

Barnacles of Japan and Bering Sea 61-84

Bdchamel sauce 118

Bering Sea and Japan, barnacles 61-84

Page.

biramosum, Scalpellum japonicum

bisselli, Leucichthys artedi

Bissell’s herring

Blackfin cf Lake Michigan

Bloater

Bloater of Lake Michigan

Bluefin

Brook trout

callistoderma, Balanus

canis, Mustelus, sense organs

cariosus, Balanus

Catophragmus (Chionelasmus) darwini

Champlain Lake, shad

Chionelasmus darwini

Chisel-mouth jack

“Chub”

Cisco

Lake Michigan

Lake Ontario

Lake Superior

Lake Tippecanoe

cismontanus, Coregonus

clupeaformis, Coregonus

Columbia River salmon, migration (see Salmon mark-
ing) 1

Common lake herring

Common whitefish

Conchoderma auritum

Coregonus

albus

cismontanus

clupeaformis

coulteri

kennicotti

nclsoni

oregonius

quadrilateralis

Stanley i

williamsoni

coulteri, Coregonus

Coulter’s whitefish

Crayfish, behavior

breeding habits

family life.

crenatus, Balanus

crinoidophilum, Pachylasma

Cristivomer namaycush

Crustacea, claw

development

egg-fixation theories

natural history

cyanopterus, Leucichthys

23*24

1
78

45-58

29-148

38
4i

39
4i
4i
4i

300

167

253

162

308

155

44I

44?

GENERAL INDEX

darwini, Catophragmus (Chionelasmus) . .

Dogfish, ears

ampullae of Lorenzini

eyes

influence of sense organs on movements

lateral line organs

sense organs, influence on movements .

touch organs

Ears of dogfish, influence on movements.

Erie great herring

Erie herring

Erie whitefish

eriensis, Leucichthys

evermanni, Balanus

Eyes of dogfish, influence on movements.

Fishes of Great Lakes

fontinalis, Salvelinus

Food value of sea mussels

Georgian Bay herring

gonionotum, Scalpellum

Grayback

Great Bear Lake herring

Great Lakes, salmonoid fishes

Great Lakes trout

harengus, Leucichthys

Herring, Arctic

Bissell’s

common lake

Erie

Erie great

Georgian Bay

jumbo

lake

Lake Huron

Rawson Lake

Saginaw Bay

Seneca Lake

Herrings, lake

Heteralepas japonica

species undetermined

vetula

hoekianus, Balanus

Huron Lake herring

huronius, Leucichthys sisco

Japan and Bering Sea, barnacles

japonica, Acasta spongites

japonica, Heteralepas

japonicum, Scalpellum

johannas, Leucichthys

Jumbo herring

kennicotti, Coregonus

Kennicott’s whitefish

Labrador whitefish

Lake Champlain shad

Lake Erie whitefish

Lake herring

Arctic

common

least

Lake herrings

Lake Huron herring

Lake Michigan blackfin

Lake Michigan bloater

Lake Michigan cisco

Page.

Lake Ontario cisco 23

Lake Superior cisco 22

Lake Superior longjaw 29

Lake Superior whitefish 35

Lake Tippecanoe cisco 10

Lake trout 2

Lake Winnepesaukee whiting 35

Lauretta whitefish 15

laur et t ae , Leucichthys 15

Least lake herring 16

Lepas anatif era 70

anserifera 70

pectinata 70

Leucichthys 3

analysis of species 4

alascanus 16

artedi 17

artedi bisselli 20

cisco 10

cisco huronius 12

cyanopterus 27

eriensis 20

harengus 6

harengus arcturus 8

johannae 24

laurettae 15

lucidus 15

manitoulinus 31

nigripinnis 26

ontariensis 13

osmeriformis 9

prognathus 23

pusillus 16

supernas 22

tullibee 32

zenithicus 29

Lobster, acclimatization 176

age at maturity 360

alimentary tract 249

anatomy 219

appendages 222

arterial supply of swimmerets 245

arteries 243

asymmetry in big claws 256

autotomy 281

balancing organs 238

behavior of young 353

blood and circulation organs 242

blood course in gill 248

body structure 219

bottom-seeking stage 347

branchial cavity and respiration 247

breaking plane and interlock of chelipeds 259

breeding habits of crayfish 300

brood, exclusion and dispersal of 326

burrowing habits 184

cannibalism 188

capture 173

central nervous system 230

changes in toothed claw at molting 278

chelipeds, breaking plane or interlock 259

claw and periodic teeth 260

claws 253

claws, asymmetry 256

color in adult 191

Page.

■ 4S-58"

• 45-58

1-42

85-128

, 1-42

. 61-84

• . 16

GENERAL INDEX.

443

Page.

Lobster, copulation 318

cracker claw 264, 266

cyclical changes in ovary 291

death causes in artificially reared larvae 349

decline of fishery 367

defensive mutilation 281

development 320

Crustacea 162

great forceps 266

ovary 290

diseases and fatalities 217

disturbances in cyclical changes of ovary 292

economic importance 169

edible parts 214

egg-fixation theories 308

egg glue 306

egg laying 305

egg-laying preparations 3°3

eggs, attachment to body 305

arrangement and distribution 305

fixation 306

number produced 298

frequency of spawning 295

eighth and later stages 346

embryo 322

enemies 215

eyes 232

family life in crayfish 167

fertilization 315

fifth stage 342

first larva 329

fisheries, apparatus 173

decline 367

history and importance 170

food and preying habits 185

food of artificially reared larvae 349

forceps, development 266

413 days old 347

fourth stage 340

gastroliths or stomach stones 208

geographical range 170

giants 194

gills 246

great chelipeds 254

great forceps 253

growth, duration of stages 359

conditions 359

rate and age at maturity 360

rate, variation 358

habits of adolescents 346

habits and instincts of adult 177

hardening of new shell 211

hatching process 327

heart 243

impregnation 318

influence of light and nocturnal habits 183

instincts and intelligence 188

internal skeleton and head 220

kidney or green gland 252

larva, first stage 329

first stage, color 331

first stage, habits 332

first stage, structure 332

food 335

Page.

Lobster, larva, second stage 33 7

larva, third stage 338

larval and later development, significant facts 350

life rate, or law of survival 375

limits of breeding season 294

liver 251

lock hinges of big claws 255

male sexual organs 312

maturity 360

messmates and parasites 215

migratory instincts 180

molting 200

hammer claw in snapping shrimp 207

molting act 204

periods, conditions, and significance 201

withdrawal of big claws 206

monstrosities 285

mouth parts 227

muscles 241

natural history of Crustacea 155

new shell, hardening 21 1

optimum temperature 182

oviduct and its periodic changes 307

pairing habits 302

parasites and messmates 215

pericardial sinus 243

period of adult life 293

peripheral stomato-gastric system 231

preparation for egg-laying 303

propagation 379

protection \ . 367

berried lobsters 370

closed seasons 370

gauge law 371

problem 369

problem, how met 369

recommendations 382

regeneration of lost parts 283

respiration 247

reproduction 288

ripe ovary 289

seminal receptacle, copulation and impregnation 318

sense organs 232

sense of taste, touch, and smell 236

sensory hairs 234

setae as related to hatching and molting 235

seventh stage 344

sexual distinctions 288

sexual maturity 293

sixth stage 344

size attained 194

skeleton before molting 207

skin and shell at molting 200

slender legs 229

sperm cells, origin and structure 312

statocysts 238

survival of young 375

symmetry in big claws 275

teeth of claw 260

toothed claw and periodic teeth 260

torsion of limb 257

touch, taste, and smell 236

transportation to markets 176

variation in position of greater forceps 274

444

GENERAL INDEX.

Lobster, weight and length in adult

young, behavior

movements under natural conditions

reaction to light

reactions to other stimuli

zoological relations.

Longe

Longjaw, Lake Ontario

Lake Superior

lucidus, Leucichthys

Mackinaw trout

Manitoba whitefish

Manitoulin tullibee

manitoulinus, Leucichthys

Menominee whitefish

Michigan Lake, blackfin

bloater.

cisco

Migration of salmon in Columbia River (see Salmon

marking) i

Mitella mitella

molliculum, Scalpellum

Movements of dogfish, influenced by sense organs

Musquaw River whitefish

Mussels, salt-water, bechamel sauce

cakes

canning

cheapness

chowder

cold storage

composition and nutritive value

creamed

croquettes

cultivation

digestibility

distribution and habitat

drying

enemies and parasites

entries

food

food value

form and structure

fried

fritters

growth

metabolism experiments

natural history

organisms constituting food

palatability

parasites

patties

pickling

poisonous

preservation methods

protein content

recipes for cooking

structure

soup

steamed

roasted

reproduction

uses

Mustelus canis, ampullae of Lorenzini

ears >

eyes

Page.

Mustelus canis, influence of sense organs on movements. 45-58

organs of lateral line 51

organs of touch 53

sense organs 45*58

Mytilus edulis ( see Mussels, salt-water) 85-128

Namaycush 2

namaycush, Cristivomer 2

Natural history of American lobster ( see Lobster) 149-408

nelsoni, Coregonus 38

nigripinnis, Leucichthys 26

Octolasmis orthogonia 70

ontariensis, Leucichthys 13

Ontario Lake, cisco 23

longjaw 23

Oregon whitefish 41

oregonius, Coregonus 41

orthogonia, Octolasmis 70

osmeriformis, Leucichthys 9

Pachylasma crinoidophilum 81

pectinata, Lepas 70

Physiology and anatomy of Atrina rigida 409-439

Pilotfish 38

porosa, Tetraclita 81

prognathus, Leucichthys 23

pusillus, Leucichthys 16

quadrilateralis, Coregonus 38

Rawson Lake herring 20

Rocky Mountain whitefish 41

rostratus, Balanus 73

Round whitefish 38

rub rum, Scalpellum 62

Saginaw Bay herring 6

Salmon, careers as shown by marking experiments 142

Columbia River, migration ( see Salmon marking). . . 129-148

Salmon marking, careers of salmon 142

chinook salmon 142

conditions and details of process 134

detailed results 139

effects on migration 138

handling of fish 138

principle and method of experiments 133

silver salmon 143

steelheads 145

tags and tools 134

technique 136

Salmon, migration in Columbia River (see Salmon mark-
ing) 129-148

Salmon, migration speed 145

Salmonoid fishes of Great Lakes 1-42

Salt-water mussels (see Mussels, salt-water) 85-128

Salvelinus fontinalis 1

Sault whitefish 35

Scalpellum gonionotum 64

Scalpellum japonicum 66

japonicum biramosum 68

molliculum 68

rubrum 62

stearnsii 61

weltnerianum 64

velutinum 62

Sea mussels (see Mussels, salt-water) 85-128

Seneca Lake herring 9

Seneca Lake smelt 9

Sense organs of dogfish, influence on movements 45*58

Shad of Lake Champlain 35

Page.

212

335

357

354

356

155

: 29-148

45-58

118

117

116

105

116

117

119

100

114

118

85-128

116

117

102

100

117

”3

123

101

116

117

GENERAL INDEX

445

Shadwaiter

Shrimp, snapping, molting of hammer claw

sisco, Leucichthys

Siscowet

Smelt, Seneca Lake

stanleyi, Coregonus

Stanley’s whitefish

stearnsii, Scalpellum

Superior Lake, cisco

longjaw

whitefish

supernas, Leucichthys

Tetraclita porosa

Thrissomimus

Tippecanoe Lake cisco

Togue

Trout, eastern brook

Great Lakes

lake

Mackinaw

Tulipi

Tullibee

Manitoulin

tullibee, Leucichthys

velutinum, Scalpellum

vetula, Heteralepas

Page.

weltnerianum, Scalpellum 64

Whitefish, Alaska 38

common 37

Coulter’s 41

Kennicott’s 39

Labrador 35

Lak e Superior 35

Lake Erie 37

lauretta 15

Manitoba 35

Menominee 38

Musquaw River 35

Oregon 41

Rocky Mountain 41

round 38

Sault 35

Stanley’s 39

Yellowstone 41

Whitefishes of Great Lakes 3-42

Whiting of Lake Winnepesaukee 35

williamsoni, Coregonus 41

Wing-shell ( see Atrina rigida) 409-439

Winnepesaukee, Lake, whiting 35

Yellowstone whitefish 41

zenithicus, Leucichthys 29

Page.

207

i-3

Internet Archive Audio

Featured

Top

Images

Featured

Top

Software

Featured

Top

Books

Featured

Top

Video

Featured

Top

Mobile Apps

Browser Extensions

Archive-It Subscription

Save Page Now

Full text of "Bulletin of the Bureau of Fisheries"

See other formats