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[ARTICLE 1.—EXTRACTED FROM THE BULLETIN OF THE VU. 8s. FISH COMMISSION
Paces 1 to 252. Plates A to J and 1 to 54.)

FOR 1895.

fee AMERICAN LOBSTER:

A STUDY OF ITS HABITS AND DEVELOPMENT.

FRANCIS HOBART HERRICK, Pu. D.,

PROFESSOR OF BIOLOGY IN ADELBERT COLLEGE OFF WESTERN RESERVE UNIVERSITY.

WASHINGTON:
GOVERNMENT PRINTING OFFICE.
SIO.

-

THE AMERICAN LOBSTER:
A STUDY OF ITS HABITS AND DEVELOPMENT.

BY

FRANCIS HOBART HERRICK, Ph. D.,

Professor of Biology in Adelbert College of Western Reserve University.

F.C. B. 1895—1

INVERTEBRATE
\ ZOOLOGY

Crustacea

“"Tde nadayv novpidwy, ide uauapwr, ide pira.
Od6ai wav Ss épvipai Tévti Kai AElorpiy1@6at.”

“Behold the dainty courides, my friend,

And see these lobsters; see how red they are,

How smooth and glossy are their hair and coats.”
Sophron, quoted by Athenwus.

“La Nature a tofijours de quoi payer les soins de
ceux qui l’examinent; il n’est point de si petit cdté ou

elle ne soit inépuisable.”
Réaumur.

“Wir finden zwar bey allen Scribenten der natiir-
lichen Historie eine Beschreibung des Fluskrebses,
wenn man aber alles was sie von selbigem gesaget
zusammnimmt, so kommt so wenig heraus, dass auch
hier das Sprichwort, (Quotidiana vilescunt, was wir
taglich vor Augen haben, achten wir nicht, allerdings

einzutreffen scheinet.”
Roesel von Rosenhof.

CONTENTS.

NIG DUG ONetesaaaeeneasieneneesiemiste = siaiare= == cieiaiainie
CHarerer I. Habitsand Environment
Distribution of the Lobster..-....---------------
Character of the Environment ------------------
Intelligence of the Lobster...-.-.---------------
The Lobster’s Powers of Movement
Periodical Migrations and their Relation to
Changes in the Environment. .-.-.------
Sensibilityto Wight..-..---.------.--<----------
Digging and Burrowing Habits ---------------
The Food of the Lobster and how it is erred
CHAPTER TT. Ieproduction.....---------.----------
The Reproductive Organs..-.....----------------
Pairing of the Lobster and of other Crustacea. -
The Laying of Eggs
Summer Eggs in Vineyard Sound ---.---.----
Summer Eggs on the Coast of Maine. -------
Fall and Winter Eggs at Woods Hole--.-.---
Fall and Winter Eggs in other places-...---
Laying of the Eggs and Absorption of Ovar-
THN OW Mo Soaceccocededwet adeeeteenssaqeeda
Number of Eggs Laid and Law of Production...
Period of Incubation at Woods Hole and Rate of
MexelopMe U tae see eee cele eso
The Hatching of the Eggs
Time of Hatching of Lobsters

at Woods

Dispersal of the Young...-......--.---..---
Variations in the Time of Watching --..----
Destruction of the Egg-Lobster and its Spawn. -
Period of Sexual Maturity
Frequency of Spawning
Relative Abundance of the Sexes..-.-...--..--.
CHAPTER III. Molting and Growth..------------ --
Harlier Observations... --.--..----------------=--
Structure and Growth of the Shell ........-...-.
The Shedding of the Shell in the Lobster-.-.---
Wigan: TieOG Ll. - 5 ee coe souescdeseseeewues
IMoltin pwRnOGeSSeaate ease eae mens eee a= ae
Habits of Molting Lobsters
Castinegoteuhe shell ieeeems=eeer = eae =
Withdrawal of the Large Claws. -....--.-----
Chstinoit SQW. ose sccsososshoonsecosusseseece
The Gastroliths
Gastroliths in the Lobster; Their Structure
and Development --4--.-2---2-e=- 52-25 --
History of the Gastroliths; Their Probable
UNCON soa noe eas aoe cicnse ecicioci=
Chemical Analysis of the Shell and Gastro-
liths

|
|
|

Page.
CHAPTER IV. Defensive Mutilation and legenera-
OOF TEC IARI: ccopccoodacmocandesose 100-108
Autotomy in the Youngand Adult. --..--.------ 100-103

Regeneration of Appendages......--.---.------ 103-104
Regeneration of the Large Chelipeds. - -.- - - 104-105
Regeneration of the Antenne and Other Ap-

JOCINGIRER 5 Scossesab > sScacococraooeBEOn or 105-107

Internal Changes in Regeneration. --.------- 107-108
CHAPTER Vj. Darnge Lobsters). --.---.--------------- 109-120
The Greatest Size Attained by the Lobster -.. - 109-117
The Relation of Weight to Length of Body ----- 118-120
CHAPTER VI. Hnemies of the Lobster..--....--.---- 120-124
Animals which prey upon the Lobster. --..----- 120-122
Parasites, Messmates, and Diseases..--.....-.--- 122-124
CHAPTER VII. The Tegumental Glands, and their
Relation to Sense Organs .....----------- 125-133
General Structure of the Tegumental Gland. .-. 125-126
GheiCemenitsGlandsten-eeerree eee ees eee 126
Immediately before Ovulation...-..--..----- 126
Immediately after Ovulation .-....-..---.--- 126-127
Historical Sketch of the Cement Gland..--. 127-128
Tegumental Glands in other Parts of the
ROG Woo nonesnonseqssassaaoubessenssEs aden 128-129
Experiments upon the Sensory Areas of the
Body and Appendages..-....------------- 129-133
CHAPTER VIII. Variations in Color .....--..---.--- 134-142
Normale Coloratione=ssee eee eeeeeeeee ee Eeeeeer a 134-185
Wariationsan’ Col onseeeresen serra eee renee 135-137
Colomofatherh So cseeeee eee ene eer eee 137
Blues Wobsterstaceseceeeeeee eee ree ea 137-138
RedssODSterseereee eee eee eee ee SnOSHenaD 138-139
Cream-colored Lobsters. .--.---..--..--..--- 139-140
Variations in Color Patterns..-..--.----.--.---- 140
Spottedsobstersesssseeerse ee ee se aee eer cace 140
Parti-colored Lobsters - 141-142
CHAPTER IX. Variations in Structure.--..--..----- 143-149
Normal Variations in the Large Claws.....----. 143
Abnormal Variations in the Claws. --.---.------ 143
Similar Claws developed on Both Sides of the
Ishi sec chases sb Gane boosoqEE SHB ere eSO Eee 143-144
Division and Repetition of Appendages.--. 144-148
Variations in Other Organs...-...--------------- 149
JMOS) BHUBTN Son605 BbOSceBabR Ob noSoeRObaanSugense 149
ON ar ype erect ccs erect tc aeisetersacte ota feicict 149
| Hermaphroditismises = seesse esate ee 149
| CHAPTER X. Structure and Development of the Re-
DLOUUCtLVEs ONO ON Sree eee eile = 150-160
The Female Reproductive Organs. --..--.------- 150
DMheiOvaTrypoccj c= oscar see eons ceases nae et 150
SUA INO ON ossc5s scence escsoscesoeseeSee 150-151
The Ovary after Ovulation.............-.-.- 151-152

4

BULLETIN OF THE UNITED STATES FISH COMMISSION.

Page.

CHAPTER X. Structure and Development of the Re-

productive Organs—Continued.
The Female Reproductive Organs—Continued.
The Structure of the Ovary at the Time of
Hatching of External Eggs......-...-.. 152-153
OriginvoftheOvaesseeccnceesseete eee eres 153
The Metamorphosis of the Germinal Vesicle. -:. 153-154
Movements of the Nucleolus through the Action

of Gravity 154-155

JEWGS Uist s ONAN So mceaserneeusconooochobe noceude 155
Development of the Reproductive Organs ...--. 156
General Development.-.-.....--..-.---.--.- 156
(ONES HEdoonopas6ae ppeneBadb aénesandeoscQUbes 156
OKO GamuconnsassbaadaksasuvaussesEpEDabs 157
Seminaltheceptacloeresscsraeesa= ale aenee 157
Development of the Seminal Receptacle..... 158
The Male Reproductive Organs 158
POSTS Saas tee cee lone oeee see cones selene 158
WVaistdeterensesmecsew=nererincr eRe nercesast 158-159
Spermatophoressesseene eeeaseecescaes eee 159-169
Spermi@ellsz sce --ese eee Male\cletere = sate ears 160

CHAPTER XI. Habits of the Lobster from time of

Hatching until the period of Maturity ... 161-166

CHAPTER XII. History of the Larval and early Ado-

lescentpher 00st emesis ieee seems 167-201
HELIStoricalPNotesmema-eeeceeccer see eceieseceeee 167-168
Methods of Studying the Young.......-...-..-- 168-169
The Embryo in Late Stages of Development. - -. - 169-170
The Hatching of the Larva --- 170
ADHOMHITS Stag Onemeet ss = ceeeiise ates canara 171-172
hesSecondtS tagesanssss@ meee eee eee eens 172-173
Thepih indus tag Op smesct nas smepel seeet cece ee 173-174
MhesMourth'Stageteescnces series eee 174-176
APHOPEILtHYS taly 6 aememactelaees setter ee ener aaa 176-177
SUNG Sb0N Se baccsocodsapeconssancaddanRoG0o0S 177-178
The Seventh Stage 178
Description of Small Lobsters (Nos. 1-6, table |

SoRmNOwbbabloss) ses seinae saeeerce sce 179-182
Molting of the Embryoand Larva. -....--..--.-- 182-184

Color Variations in the Young Lobster.-.-......-.- 184

Page.
CHAPTER XII. History of the Larval and carly Ado-
| lescent Periods—Continued.
The Death-teigning Habit..-.......... asebacudes 184-186
TheHoodiofithe Warvassee see seeeeeee 186-187
Heliotropism of Larval Lobsters 187-189
Mortalityiot Lanvee---sseee-- seer eee eee ete 190
Effect of increased Temperature upon the Rate
of Development of Larve.....----..... 190-191
Development and Morphology of the Body and
JN) WOES) pocpasseeancosceconaoscooe- 191
The: Bodye2s.en-2--s- ose ee eee eee eee 191-193
The Visual Organs and Appendages .-.....-. 193-197

Development of the First Pair of Pleopods.- 197-200
The Metamorphosis of the European lobster,

Homarus gommarus.....------.--++----- 200
The Shortening of the Metamorphosis of the
100) OS) K2) ds Pe peseneaeeaareoneaoseadeccooccs 200-201
CHAPTER XIII. Embryology of the Lobster........- 202-217
Normal Developm entiee = esse: see eee ee eeee 202
The Maturation and Segmentation of the
Jf eecane pbishoneSsococsoneakacoseosesce 202-203
External Phenomena of Segmentation ...... 208-205
Internal Changes in Segmentation 205-206
The Invagination Stage ...-.....--.--.-...-- 206-209
Later Stages in Embryonic Development -.- 209-210
History, of Yiolk- Cells teerm-ne-e = hese 210-211
Degenerationvol/Cellsy eee. aa eee 211-213
Abnormal Development..........--.---- 213
segmentation of the Egg 213-214
Invagination and Egg-Nauplius Stages..... 214-216
Double Monsters in Ovum and Larva -..-...-- 216-217
Note on the Development of Cambarus -.--. 217-218
CHAPTER XIV. Summary of Observations ..--..... 219-225
APPENDIX I. Preparation of the Eggs.------------- 226-227
APPENDIX II; Composition of the Shell and Gastro-
liths of the Lobster. By Professor A1-
| bert Wirasmithsieeceeese =. a. eeeeee 227-228
APPENDIX] EE eBibliosnaphy eeeere eee eee eee 229-937
APPENDIX IV. Description of Plates........-...... 238-252

1.—THE AMERICAN LOBSTER: A STUDY OF ITS HABITS AND DEVELOPMENT.

By FRANCIS HOBART HERRICK,
Professor of Biology in Adelbert College of Western Reserve University.

INTRODUCTION.
I.

While working on the embryology of Alpheus several years ago, I decided to study
the development of the lobster for the purpose of comparison. An opportunity was
offered in the summer of 1889, which I spent at the laboratory of the United States
Fish Commission at Woods Hole, Massachusetts. In the spring of that year I had also
received, through the kindness of Dr. G. H. Parker, a considerable quantity of embryo-
logical material of the lobster, representing particularly its later stages of development.

In the spring of 1890 I was invited by Hon. Marshall McDonald, United States
Commissioner of Fisheries, to prepare as complete a work as possible upon the habits
and development or general biology of the lobster. Accordingly during the past five
years I have devoted all the time which could be spared from professional duties to
this research. For a part of each summer, from June to the latter part of August, I
have enjoyed the excellent facilities for study which the laboratory of the Fish Com.
mission at Woods Hole affords, and in the autumn of 1893 I was enabled to carry my
observations into the field by a journey along the coasts of Massachusetts and Maine
and into the Province of New Brunswick.

The materials, therefore, upon which this work is based have been gathered from
a large number of different points, although the most systematic and prolonged
observations have been made at Woods Hole. In this pleasant task I have been aided
by the friendly efforts of many who have made collections, particularly of eggs, at
widely separated parts of the coast and at different times of the year. These I have
gratefully acknowledged in the pages of this work.

To everyone at the Woods Hole station I am indebted for many kindnesses, but
particularly to Hon. Marshall McDonald, whose aid and encouragement I have con-
stantly received, and to Mr. Richard Rathbun, of the United States Fish Commission,
who has forwarded my plans in every possible way.

II.

During the course of this study I have published several papers embodying the
results of my researches (91-93, 96-101),' but these should not be consulted without
reference to this final revision of my work. Whatever errors this may contain I must
leave for other naturalists to rectify.

‘Italic figures in parentheses refer to the numbers of publications in the Bibliography at the end
of this paper.

5

6 BULLETIN OF THE UNITED STATES FISH COMMISSION.

The lobster, though it may be rightfully called the King of the Crustacea, in
consideration of both its size and strength, its abundance and economic value, had,
until recently, been singularly neglected by naturalists. Even its breeding habits
were not understood, and so little was our knowledge of many phases of its general
biology that I determined from the first to devote ample time to this important subject.

Rathbun, who brought together what was known concerning the habits of the
lobster in a contribution to the Natural History of Useful Aquatic Animals, published
in 1887 (155), spoke as follows:

Although the lobster is one of the most important of our food invertebrates, careful observa-
tions regarding its natural history, and especially its breeding habits, rate of growth, etc., have been
strangely neglected. This fact is greatly to be deplored, considering that the lobster has recently
become the subject of important legislation by the several States which it inhabits and that its culti-
vation by artificial means has been frequently attempted. * * * The success attending the artificial
breeding of several of our food-fishes has inspired the hope that similar methods might succeed with
regard to the lobster, and many persons are now awaiting with interest the results of experiment in that
direction. It is very certain, however, that the breeding of lobsters can never be successfully carried
on until we have become acquainted with at least the main features of their natural history. The
artificial cultivation of animals can only progress through the fulfillment of natural laws, which
must be thoroughly understood before they can be properly applied. As it is, however, the would-be
experimenters in the matter of lobster breeding must still follow a very uncertain pathway, meeting
with numerous failures which previous studies might have arrested (p. 781).

Many facts relating more particularly to the larval development and reproduction
have important economic bearings, and for the benefit of those who have neither the
time nor inclination to read the details of this paper I have added a careful summary
of the principal observations and conclusions at the end (Chapter x1v).

Under the subjects discussed in the various chapters I have given all the impor-
tant historical references, and have added a full bibliography. There has grown up
around every well-known animal like the lobster a considerable mass of popular
pseudo-scientific literature, which is of no value either as literature or science. and
may well be ignored.

III.

The lobster is singularly free from common names, in this country at least. Itis
rarely confused with any other animal unless it be with the Palinurus of the Pacific
Coast and the West Indies, and with some of the larger species of crayfish, all of which,
however, are very distinct, the latter being inhabitants of fresh water.

Patrick Brown tells us in his *‘ History of Jamaica,” published in 1789, that the
Palinurus was then commonly called the “‘ horned lobster or great crayfish.” The terms
rock lobster and spiny lobster are still applied to it in this country and in Europe,
but the entire lack of large claws—one of the most striking characteristics of the
lobster—its spines, brilliant coloring, and enormous antenn, should prevent the
most inobservant person from confusing it with so distinet a form.

The lobster, as I have explained in Chapters 11 and 11 (pp. 55, 82), has acquired
numerous epithets while carrying eggs or passing through the various phases of
the molt.

The old generic name Astacus (dstaxoz or dctaxoc) was used by Aristotle and
the older naturalists down to the present century to embrace the crayfishes and the
lobsters proper. Aristotle thus speaks in the fourth book of his History of Animals

THE AMERICAN LOBSTER. “

of “the small astaci, which are bred in the rivers”! showing that the reference is
undoubtedly to the crayfish.

Atheneus frequently mentions the Astacus in the third book of The Deipnosoph-
ists, where, as in the passage quoted below, he undoubtedly had in mind the lobster.
Thisis from a famous poem of Archestratus, wherein, as Athenzeus remarks, he never
once mentions the crab by the name of zdpafos, yet does speak of the deraxuc.

But passing our trifles, buy an astacus,
Which has long hands and heavy, too, but feet
Of delicate smallness, and which slowly walks
Over the earth’s face. A goodly troop there are
Of such, and those of finest flavor where
The isles of Lipara do gem the ocean:
And many le deep in the broad Hellespont.
(The Deipnosophists; Bk. 11, tr. by C. D. Yonge, 1854.)

Atheneus then quotes from another author, Epicharmus, to show that the deraxoc
mentioned by Archestratus is the same as the zapafos:

There are astaci and colybdenie, both equipped
With little feet and long hands, both coming under
The name of xapafoe.

The English word lobster is. from the old English lopystre,? which is probably a
corruption of the Latin locusta—English, locust—a name used by Pliny in speaking of
the lobster in his Natural History. Thus, in the ninth book, he says: “The lobsters,
being of that kind which want blood, are protected by a weak shell.”* In the next
section of the same chapter there is a sentence, in which the astaci are mentioned as
one of the genera of crabs. It is possible that lobsters are here referred to, but the
meaning is doubtful.

Gesner, whose remarkable History of Animals was published at Ziirich between
1551 and 1587, speaks of the lobster under the Aristotlean name of Astacus, and adds
a very interesting Synonymy. He says:

The English call the Astacus a creuyse of the sea,° for the lopstar of the English is the locust, not
the astacus; although Eliot in different places has translated astaeus, locust, and leo as a lopster.®

' Toi¢ aarakoi¢ pKpoic, of yiyvovTat kad év Toic morauoic. A. H. 4. 4.

* Longusta or langusta, la langouste of the French, the Palinurus, probably has the same origin.
This was corrupted to ‘“‘long oyster” in the West Indies. (See The Natural History of Jamaica, by
Hans Sloane, vol. 11, p. 271.)

* Locust crusta fragile muniuntur in eo genere quod caret sanguine. Latent mensibus quinis,
similiter cancri qui eodem tempore occultantur, et ambo veris principio senectutem anguium more
exuerunt renovatione tergorum. Lib. 1x, Cap. Xxx, sec. 50. :

4Cancrorum genera carabi, astaci maeae, paguri, heracleotici, leones et alia ignobiliora. Ibid.,

sec. ol.
5 Creuyse according to Skeat, is probably a variation in the spelling of the Middle English for
erayfish (erayf-ish), —— crevis, creves, crevise, or creveys; Old French, crevisse, or eserevisse ; Modern

French, éerevisse; Old High German, crebez; Middle High German, krebez; German, Arebs, allied to
Krabbe.

‘Anglis astacus est a crewyse of the sea, nam lopstar Anglorum, locusta est, non astacus; quam-
quam Eliota diversis locis astacuim locustam et leonem interpretatus a Lopster (75, De Astaco, pp.
113-121). [Eliota is Sir Thomas Elyot, who published a Latin-English dictionary in 1538.]

8 BULLETIN OF THE UNITED STATES FISH COMMISSION.

Some light is thrown upon this passage by the German translation of Gesner’s
Historia Animalium, published at Frankfort in 1598, where the lobster is spoken of
as Humer oder grossen Meerkrebs. The Latin name Astacus is also given to it. A
paragraph, which I did not find in the original, is as follows:

These sea-crabs mentioned above, are called by Pliny sea-elephants, on account of their size and
strength. They are also regarded by some as sea-lions, and by such names are commonly known at
Montpelier. !

The lobster was also called by the Greeks zdypyapos, Latin gammarus, probably from
its arched back, from which Spanish, camaron, and the Italian gambaro are derived.
Gesner tells us that the crayfish, was often called simply gambaro, to distinguish it
from the lobster gambaro di mari; that to the French and Normans the lobster was
known as Homar; to the Germans as Humer. In Norway, Sweden, Denmark, and
Germany it is now called Hummer? This in French became Homard (Homar, Latin-
ized form Homarus). It has been suggested by Boeck that the name may possibly
have come from the Norse verb homa, meaning to go backward.

Gesner adds that the lobster was called by the Venetians astase vecari andio; by
the Illyrians, larantola (or caranthola), and by the Swiss, langroit or eserevice de mer.
The Dutch call the lobster Zeekruft or sea-crayfish, while it is known to the Turks of.
Constantinople as liczuda or lichuda.

According to Boeck there are numerous poetical allusions to the lobster in the
Eddas and Sagas. Thus the sea is described as “the path of the lobster” in Olaf der
Heilige’s Saga, and in Olaf Tryggvason’s Saga it is said that “the wave-horses run
over the fields of the lobster,” meaning the ships that sail on the waves. ‘To be at
the bottom with the lobster” is to drown, as in the song of Snigly Holle. ‘In the
Selxolle Songs of Kinar Gilson, in Bishop Gudmund’s Saga, the term “the light of
the lobster,” equivalent to the fire of the sea or gold, is used. In the same place the
expression, “the horse of the lobster mountain,” meaning the ship, is used. Finally
there is found in the poem Liknar-braut, the expression ‘land lobster,” meaning a
serpent or dragon. (20, p. 224.)

IV.

Excluding from our consideration the Palinurus or langouste and the Norwegian
lobster, Nephrops norvegicus, two species belonging to this genus are now known,
namely:

Homarus, Milne Edwards.

(1) Homarus gammarus (Linn.); = Cancer gammarus (Linn.) ;
= Homarus vulgaris (M. Edw.) European Lobster.
(2) Homarus americanus (M. Edw.) American Lobster.
A third form, H. capensis, has been imperfectly described from the Cape of Good
Hope, but it is doubtful if it belongs in this genus. (See 102, p. 754, note 4.)

' Diese obgenandte Meerkrebsz nennet Plinius Meerhelffant von wegen irer grésse und stiircke
werden sonst auch von etlichen Meerléwen geachtet sind mit solehem Namen von menniglichen zu
Mompelier genennt worden . . . . . Fischbuch; translated from the original of Conrad Gesner into
German by Conrad Forer; p. 125; Franckfurt, 1598.

The animal described and figured on the next page of this work and called the Small Lobster or
Small Sea-crab—Astacus marinus parvus—is probably a species of Galatea. Palinurus is described as
the Meerstoffel. Synonyms are: A Species of Lobster; A Kind of Large Sea-crab; Locusta; Carabus.

2 The old Norwegian and Danish writers, Pantoppidans (1752, 752), Strém (1762), Bomares (1767),
and Leems (1767) speak of the lobster as Hummer, while by Olafssens and Povelsens (1772) it is called
Humar, according to Fabricius. These dates refer to works. For bibliography see Otho and J. C.
Fabricius (63-64).

THE AMERICAN LOBSTER. 9

I will now add a fuller synonymy of the technical names which have been applied
to the European and American lobsters.

EUROPEAN SPECIES,

MaOUseeeee eae eee ODL. hondelet (267). Cancer gammarus..-.--1761. Linné (722).
Astactis sens. ........---- 1618. Aldrovandus (2). | 1776. Miiller (239).
-Astacus marinus communis 1657. Jonston (207). 1795. Herbst (S88) [2d ed.].
Astacus marinus ...--..--- 1553. Belon (75). | 1829. Latreille(/75)[2d ed. ].

1758. Seba (779). | Aslacus europeus..---- 1837. Couch (45).

1762. Baster (8). Homarus vulgaris. ..-- 1837. Milne Edwards (58),

1777. Pennant (757). 1853. Bell (74).

1792. Fabricius (67). 1863. Heller (S87).

1811. Olivier (143). | Homarus marinus. .--- 1868. Bate (70).

1838. Lamarck (713) | Astacus gammarus ...-1819. Leach (117).

[8d ed.]. | 1857. White (202).
1825. Desmarest (52). 1893. Stebbinge (786).

1826. Risso (766). |
1842. Rathke (7260). |

AMERICAN SPECIES.

Astacus marinus america- | Homarus americanus..1837. Milne Edwards (58)
MUS ae acne ces ce 1758. Seba (179). | and mostsubsequent
Astacus marinus ......---- 1817. Latreille (725) writers.
[1st ed.]. | Astacus americanus ..-1893. Stebbing (1860).

1817. Say (177). |

Latreille,! in 1810, designated as the type of the old genus Astacus the species
A, fluviatilis Fabricius (= Cancer astacus Linné), which is the European crayfish. In
1815 Leach began to dismember this genus by giving to the Norwegian lobster the
name Nephrops. Later, in 1819 (117),? he proposed the generic term Potamobius to
embrace the true craytishes, leaving the lobsters alone in possession of the Aristotelian
name. This division would transfer the type species of Astacus (A. fluviatilis) to the
genus Potamobius, which is contrary to the rules of zoological nomenclature, and can
not be accepted. In 1837 the lobsters were placed by Milne Edwards in a distinct
genus, Homarus, while the elder name was retained for the crayfishes. Spence Bate
was in favor of uniting the generic name of Milne Edwards to the specific name of
Fabricius, calling the European species Homarus marinus (Fabr.). The proposal of
Leach “to use Astacus for the lobsters and to give a new generic name (Potamobius)
to the fresh-water crayfishes,” would, in the opinion of Huxley, “ have had the advan-
tage of retaining the primitive signification of dorazéc. But Potamobius had already
been used in another sense, and the change introduced by Milne Edwards is so gen-
erally adopted that it would be confusing to attempt any further alteration” (102).
Previous to 1819 the name Potamobie had been used by Leach®* in a list of the known
genera of Crustacea. It was, however, a nomen nudum, which would have permitted
the use of the name Potamobius for the crayfishes had the genus been correctly formed.
Stebbing (186), apparently unaware of Latreille’s restriction, proposed to restore the
old terminology of Leach.

According to Milne Edwards’s classification, which I have adopted, the common
European crayfish should be called Astacus astacus (Linn.), the European lobster
Homarus gammarus (-bimm.) gine the American HOOT Homarus americanus (M. Edw.).

' Considérations Générales sur V Or ae Naturel des Animaux Broo les Guanes ries Crustacés, Flas
Arachnides, et des Insectes, p. 422. Paris, 1810.

2 George Samouelle’s Entomologist’s Useful Compendium, p.95. London, 1819.

3 Dictionnaire des Sciences Naturelles, X11, p. 75, 1818.

For the preceding references I am indebted to the kindness of Dr. Walter Faxon and Miss Mary J.
Rathbun, and I desire to acknowledge the aid I have received from them on the nomenclature discussed
in the last two paragraphs of this page.

10 BULLETIN OF, THE UNITED STATES FISH COMMISSION.

Vv.

Although the lobster has a place in the literature of the Old World, it is seldom
mentioned by American writers. Rathbun, who was tlie first to give a history of the
American lobster fisheries, says that the great abundance and rare flavor of the
lobster “are not infrequently mentioned in the early annals of New England, and it
probably formed an important element in the food-supply of the seacoast inhabitants
of colonial times. As a separate industry, however, the lobster fishery does not date
back much, if any, beyond the beginning of the present century, and it appears to
have been first developed on the Massachusetts coast, in the region of Cape Cod and
Boston, although some fishing was done as early as 1810 among the Elizabeth Islands
and on the coast of Connecticut. Strangely enough this industry was not extended
to the coast of Maine, where it subsequently attained its greatest proportions, until
about 1840.” (156.)

In an account of marketing in Boston in 1740, among various kinds of meats and
game, ‘‘oysters and lobsters” are mentioned “in course, the latter in large size at
3 half-pence each.” (200, vol. 11, p. 540.)

Kaln, the Swedish traveler, writing in 1771, thus speaks of the abundance of sea
food on the shores of Long Island:

The soil of the southern part of the island is very poor; but this deficiency is made up by a vast
quantity of oysters, lobsters, crabs, several kinds of fish, and numbers of water fowl, all of which are
there far more abundant than on the northern shores of the island. Therefore the Indians formerly
chose the southern part to live in, because they subsisted on oysters and other productions of the sea,
(108, vol. 2, pp. 226-227.)

The older writers had little to say of the sea and its products in New England,
yet many interesting facts could probably be gathered by a careful examination of all
avallable sources.

VI.

Lobsters are caught in pots or traps made of laths, nailed to a wooden frame,
with a funnel-shaped opening at each end. ‘The traps are commonly 4 feet long, 2 feet
wide, and 18 inches high. ‘The funnels are usually netted out of manila twine. The
pots are weighted with stones or bricks, and set either in single warps or in trawls of
from 8 to 40 pots each. Each pot has a buoy line to which a wooden spindle-shaped
buoy is attached. The latter bears the owner’s mark or stamp, and shows the position
of the trap. The traps are baited with fish, such as herrings, sculpins, or flounders,
and the lobster, when once induced to come inside the pot, seldom escapes, unless small
enough to crawl between the slats. It has been estimated that half a million lobster
traps have been in use in the Maritime Provinces during a single year.

The old-fashioned hoop nets formerly in use consisted of a single iron ring or hoop
to which a net with cord was attached. When baited they had to be closely watched
and pulled up from time to time, in order to secure the lobster before he could get out
of the net.

The lobster fishery is conducted chiefly in the spring and. summer months. The
pots are tended from small boats, and the catch is kept in floating cars moored in
some protected spot near the shore. Welled fishing smacks, or more rarely welled
steamers, gather up the lobsters from the fishermen and carry them to the canneries
and to the markets in the large distributing centers, such as Portland, Boston, and
New York. Lobsters are shipped alive in barrels, with ice in summer, to many parts of

Ts

THE AMERICAN LOBSTER. 11

the country. The winter shipment is also very considerable. Large numbers are
immediately boiled for home consumption, while many are kept alive in floating cars
at the market until required. The impounding of lobsters, or placing them in large
inclosures of salt water, called pounds, where they can be kept during the winter,
is now successfully practiced on a large seale.

VII.

We have witnessed in the lobster fishery for many years past the anomaly of a
declining industry with a yearly increasing vield, but with the gradual diminution in
the size of the lobsters caught and an undue increase in the number of traps and
fishermen. ‘How much longer,” writes the inspector of fisheries of New Brunswick,
“an increased catch can be made out of a diminishing supply is a problem of some
interest to those who have watched the rise, progress, and decay of this industry.” !

In 1886 fully 90,000,000 lobsters were captured in Canada,’ principally in Nova
Scotia, New Brunswick, Prince Edward Island, and Quebec. Out of this vast number
nearly 34,000,000 were taken in New Brunswick alone, and 22,000,000 in Prince
Edward Island. These numbers are extraordinary, when we consider, as in the last
instance, the small extent of the coast and the narrow limits of the fishing season.

In regard to the catch of lobsters in New Brunswick for 1886, the inspector of
fisheries says in his report *® that the average size is diminishing, and “to fill a pound
can now requires rather more than an average of six lobsters—about 24 ounces of
meat per fish. The returns show 4,661,812 cans preserved, and 4,290 tons of fresh
lobsters. In order to fill these cans, 28,000,000 lobsters were killed. If to these we
add the number exported fresh, allowing 14 pounds to each, which is a large average,
the number killed during the season will be 33,720,000.” +

In 1887 about 70,000,000 lobsters were taken in Canada, and in 1892 upward of
68,000,000 lobsters (estimated as above) were captured, valued at nearly $2,000,000.°

In 1884 the catch of lobsters in New Brunswick amounted to 5,662,072 cans and
1,709 tons, valued at $900,580, the number of traps in use being 105,984. In 1892 the
number of traps had increased to 172,022, an increase of over 60 per cent, while the
product had decreased by nearly the same amount, being 3,204,520 cans and 1,132
tons, valued at only $493,804.°

The average annual yield of the Norwegian lobster fishery from 1879 to 1884 is

Fisheries, Dominion of Canada, 1886, p. 146.)

2This estimate is based upon the official statistical return of the lobster fishery, allowing five
lobsters to a pound can of meat, and a trifle over 2 pounds in weight to each lobster. ‘The yield in
1892 was 16,434,431 pounds in cans, and 8,662 tons of fresh lobsters, valued at $2,638,394. (Report on
the Lobster Industry of Canada for 1892. Supplement to the Twenty-fifth Annual Report of the
Department of Marine and Fisheries, No. 10d, Ottawa, 1893.)

3’ Annual Report of the Department of Fisheries of the Dominion of Canada, 1886.

*Tbid.

5It should be remembered that these estimates, large as they seem, are based upon statistics
which are generally reliable, and probably fall far below the number of animals annually killed; for
they do not include the number of undersized lobsters illegally used for canning, nor those used
as food by fishermen and their families. Then there is, besides, the vast number of lobsters which
annually fall a prey to other enemies than man.

‘Report on the Lobster Industry of Canada, 1892, Supplement to the Twenty-fifth Annual
Report of the Department of Marine and lisheries, No. 10d, Ottawa, 1893.

ile, BULLETIN OF THE UNITED STATES FISH COMMISSION

being shipped to England.’ About 3,000,000 lobsters are said to be taken in the
British Isles in a year, while the total number captured on the North Atlantic coast
of America has undoubtedly in some years reached close to 100,000,000.

The total quantity of lobsters taken in the United States in 1880 was 20,238,683
pounds, valued at $488,432; of this quantity, 19,946,733 pounds, worth $477,484, were
taken in the New England States, and 291,950 pounds, valued at $10,948, in the
Middle Atlantic States. In 1887 the United States lobster catch was 28,882,180
pounds, with a market value of $799,717, of which 28,627,600 pounds, worth $784,238,
were caught in New England and 254,580 pounds, valued at $15,479, in the Middle
Atlantic region. The output of the New England lobster fishery in 1889 was
30,449,603 pounds, valued at $833,736; of this catch, 25,001,351 pounds, worth
$574,165, were taken in Maine.

The division of the United States Fish Commission concerned with statistics and
methods of fisheries took a complete census of the lobster fishery of New York, New
Jersey, and Delaware in 1892,’ and in 1893 canvassed the lobster fishery of the New
England States. Through the courtesy of Dr. H. M. Smith, the assistant in charge of
the division, I am able to present in the following table the results of these inquiries.

The total number of persons engaged in the lobster fishery of the United States
in 1892 was 3,766; of these, 2,628 were in Maine and 616 in Massachusetts. The
vessels employed in lobster fishing numbered 58, valued at nearly $75,000. The
number of boats used was 3,976, having a value of $325,000. Over 200,000 traps,
worth $221,000, were operated. The total investment in the fishery, including the
value of live ears ($25,835), was $648,065, distributed among the different States as
shown in the table. The quantity of lobsters taken and sold by United States
fishermen in 1892 was 23,724,525 pounds, for which $1,062,392 was received. Of this
output, 17,642,677 pounds, valued at $663,043. were caught in Maine and 3,182,270
pounds, worth $205,638, in Massachusetts.

Table showing the extent of the lobster fishery of the United States in 1892.

Vessels, boats, and traps used.

=
| Syne Lobsters taken.
States. mara Giaik Vessels. | Boats. Traps or pots.
loyed. | Gas | SATE zoe zi |
| ploy No. | Value.| No. | Value. No. | Value. Pounds. Value.
f | | le 7 | |
Maine set] 5-2: eee oe ee 2, 628- 7 | $7,050 | 2, 888 | $242,629 153, 043 | $143, 709 | 17, 642, 677 | $663, 043
New Hampshire ..-.--- 2 Blpecerelloabasce: 29 | 594 1, 393 | 2, 786 196, 350 11, 790
Massachusetts -.--- 3 616 2 1,710 739 | 47,162 26,192 | 38,479 | 3, 182,270 205, 638
Rhode Island -.....--.-. | 145 12 8, 455 86 | 15,3520 6, 341 10, 090 | 774, 100 53, 762
| GConnecticut..---..----- | 258 34 | 46, 265 183 17,585 | 10, 105 22,178 | 1, 614, 530 101, 358
NGI YQOaS snopacesseoce 55 2 | 9,880 34 | 1, 140 | 2, 240 | 3, 469 165, 093 15, 655
ING Wi JIOLSeYyjeae sine | 36 1 1,475 16 | 1, 062 678 | 1,099 143, 905 10, 861
Delawaresee-ceseeae eae | PP leccsrelleandenti i 40 21 53 5, 600 285
Totalweeee acces 3, 766 58 | 74,835 | 3,976 325, 532 | 200, 013 221, 863 | 23, 724,525 | 1, 062, 392
| |

Between 1887 and 1892 the decline in the lobster fishery of the United States was
over 5,000,006 pounds, although the value of the catch was more than $260,000 greater
in the latter year. When the yield and value of the fishery in the New England
States in 1892 are compared with the results of the fishery in 1889, we find a falling

1 Bulletin of the United States Fish Commission, vol. v1; also Report of the United States Fish
Commissioner for 1889.

> See a Statistical Report on the Fisheries of the Middle Atlantic States, by Hugh M. Smith, . p.,
Bulletin of the United States Fish Commission for 1894, page 455.

THE AMERICAN LOBSTER 13
off of more than 7,000,000 pounds, or over 23 per cent, buf an increase in the market
value of the output of over $200,000, or nearly 25 per cent. These figures illustrate
very forcibly the decline which, unless speedily checked, threatens to destroy this
valuable fishery.

Five attempts to transport lobsters alive across the continent and plant them in
the Pacific Ocean have been made by the United States Fish Commission (157), in
1875-1889, and all but the first have proved successful. No evidence has, however,
yet appeared to show that the lobster has multiplied and thriven in its new environ-
ment. More recently attempts have been made, with some degree of success, to ship
lobsters across the Atlantic, and deliver them alive in the markets of London and
Paris.

England, France, and Germany are the principal markets for the export trade
outside of the United States, but, like other preserved meats, the canned lobster is
shipped to all parts of the world.

VIIl.

Civilized man is sweeping off the face of the earth one after another some of its
most interesting and valuable animals, by a lack of foresight and selfish zeal unworthy
of the savage. If man had as ready access to the submarine fields as to the forests
and plains, it is easy to imagine how much havoc he would spread. The ocean indeed
seems to be as inexhaustible in its animal life as it is apparently limitless in extent
and fathomless in depth, but we are apt to forget that marine animals may be as
restricted in their distribution as terrestrial forms, and as nicely adjusted to their
environment. Thus, as we shall see, the American lobster occupies only a narrow
strip along a part of the North Atlantic coast, and while it is probably not possible
to exterminate such an animal, it is possible to so reduce its numbers that its fishing
becomes unprofitable, as has already been done in many places.

The only ways open to secure an increase in the lobster are to protect the spawn-
lobsters, or to protect the immature until they are able to reproduce, or to take the
eges from the lobsters themselves and hatch them artificially. The latter is the
method which has been adopted and is now in use in the British Maritime Provinces,
and less extensively in the United States.

In an earlier paper, published in the United States Fish Commission Bulletin for
1893 (pp. 75-86), I have discussed the question of the artificial propagation of the
lobster, and have called attention to what seem to me the weakest points in the
present method and what the most promising field for future experiments.

ADELBERT COLLEGE, CLEVELAND, OHIO,

June, 1895.

Chapter 1—HABITS AND ENVIRONMENT.

DISTRIBUTION OF THE LOBSTER.

The American lobster inhabits the coastal waters of the Atlantic Ocean from
Labrador to Delaware, and occurs in depths of from less than 1 to more than 100
fathoms. It is thus confined to a strip of the Atlantic Ocean about 1,300 miles long,
and at some points (as on the coast of Maine, where there is an extensive fishery in the
outward islands) from 30 to upward of 50 miles wide. Its geographical range covers
about 20 degrees of north latitude, from the thirty-fifth to the fifty-second parallel;
but owing to the extreme irregularity of the coast the actual area of distribution 1s
much greater. At present the lobster is most abundant and attains the largest size
in the northern half of its range, that is upon the coasts of Maine and the British
Maritime Provinces.

The lobster was recorded from Labrador by Packard in 1863. “The rocky shores,”
he says, ‘“‘exposed to surf from the gulf, did not seem to harbor any animal life, but a
narrow, interrupted belt of sand and mué flats in Salmon Bay” (near Caribou Island)
supports a feeble assemblage of littoral forms (144). Under the rocks and seaweed the
lobster was occasionally seen. At Henley Harbor, a little above the Straits of Belle
Isle, it is mentioned as “rare.” This seems to be the northern limit of the lobster.
At Hopedaie, 200 miles above this point, he showed a picture of the lobster to one of
the native Eskimos, who signified that it was not found there (148).

The lobster was common at Anticosti and Mingan islands (145), where coiiections
were made by Verrill, Hyatt, and Shaler in 1861. Stearns (185), who asserts that
“lobsters were found everywhere along the coast of Labrador,” is doubtless in error.
He probably had in mind the “ Gulf coast,” or “Inner Labrador,” as the territory of
the Province of Quebec which stretches southwesterly from the Straits of Belle Isle
is often erroneously called.

In speaking of the habits of lobsters in ‘‘ Labrador,” Stearns says:

Very often the beach is covered with rocks, large and small, interspersed with holes and pits
filled with water at low tide. The seaweed grows over these places, thus affording capital hiding-
places. One can often procure 100 lobsters in an afternoon from a strip of the beach hardly as many
yards long. The small boys hunt them with long poles on the ends of which are tied large cod hooks.
With these the boys reach in and feel about in the holes and under the rocks until they feel the shell
of a lobster, when a smart or careful haul, as the case may require, generally brings the animal out of
its snug quarters. [These lobsters] are seldom very large, while the very young ones appear not to
come inshore among the rocks to any great extent (185).

Dr. W. Wakeham, to whose kindness I am indebted for much interesting infor-
mation on the northerly range of the lobster, writes as follows:

My own experience of the Labrador coast does not go beyond Chateau Bay at the northeastern

entrance to the straits of Belle Isle. From this point west along the Labrador and north shore of
Quebec, I have found the lobster everywhere fairly abundant up to Manicouagan in the river St.

14

THE AMERICAN LOBSTER. 15

Lawrence. I have inquired of Gaspé whalers who are in the habit of going as far as Cape Harrison,
on the coast of Labrador, but they all tell me that they have never taken a lobster below St. Charles—
that is, a few miles north of Chateau Bay. West of Chateau Bay, as I have said, they are found all
along the coast, but not in paying quantities. Several attempts have been made to operate canneries on
this coast, but they have one after another been abandoned. ‘The lobsters seem to give out suddenly.
They are all caught up when the traps are first set. Of course the water is too deep for any general
fishery, and it is only in shoal bays and harbors that traps can be used.

In reply to a letter of inquiry from Dr. Wakeham, Mr. P. M. McKenzie, one of
the chief factors of the Hudson Bay Company, says that he has been on the Labrador
coast and entrance of Hudson Straits for fourteen years, and has “‘never seen a
lobster or heard of any being caught between Grady Harbor (longitude W. 56° 25/,
latitude 53° 46’) and Cape Chudleigh.” He says further, that he does not think they
oceur between Grady Harbor and the straits of Belle Isle, but “all along the Gulf
from Seven Islands to St. Augustine there are a great many at certain points.”

Mr. W. H. Whitely, overseer of ,fisheries at the straits, writes to the same effect:

Lobsters are not found below [i. e., east of] the narrows of the straits of Belle Isle [the lowest
point, a place called Brodore Bay]. Some are found on the southern or Newfoundland side of the
straits. They are not plenty at any place within 100 miles west of the north side of the straits of
Belle Isle, but a few are found in places sheltered from rough water and drifting ice. I have never
heard of any lobsters being seen at any point on the Labrador east of the straits.

From the character and abundance of this testimony we may safely conclude that
the lobster is not found on the coast of Labrador very far beyond the straits of Belle
Isle, or not many miles north of Henley Harbor (about 52° north latitude). From the
straits northward the temperature is said to fall rapidly, owing to the arctic current
which flows south, and the presence of ice, which is carried along with it close to the
land. We should not, therefore, expect to meet with the lobster, except as a very rare
stragegler, north of the straits.

It is interesting to find, on the other hand, that Fabricius (63) includes the lobster
(Cancer gammarus L.) in his Fauna Groenlandica. He is particular to state, however,
that he does so upon the authority of others, as he had never seen the lobster in
Greenland himself. He says that the lobster is found under the name of Pekkuk in
the Greenlandish dictionary. He had heard the natives distinguish the smaller
Squillas by the name of Pekkungoit, from a much larger form (Cancris), called Pek-
kuit or Pekkurksoit, and very similar to the ““Gammari.” This name may have been
derived from the Esquimaux of the southern Labrador coast or from Iceland, where,
according to Mohr’s “ Islandske Naturhistorie,” the European lobster ‘‘has been found
by Dr. Poulsen in Grondevig, but it does not extend to Greenland or Spitzbergen” (20).

De Kay, writing in 1844, remarks that while the lobster was taken in compara-
tively small quantities on the New Jersey coast, ‘two years after building the break-
water in Delaware Bay, lobsters made their appearance there in great quantities.”
He also says that in about the year 1814 General Pinckney ‘‘caused a ear full of
lobsters to be emptied into the harbor of Charleston, South Carolina. <A few of their
survivors, or their descendants, were captured about ten years since, but, as I am
informed, they were the last.” (51, p. 25.)

The stonework of Delaware Breakwater, says Rathbun (155), may be considered
the southern boundary of the lobster, although he has recorded several instances of
its occurrence south of this point. Thus it has been said that lobsters have been seen
along the beach in the surf near Indian River Inlet, Delaware. Two or three have

16 BULLETIN OF THE UNITED STATES FISH COMMISSION.

been recorded at Johnstown, in the northeastern corner of Virginia, ‘‘and in October
1884, the United States Fish Commission steamer Albatross obtained a single speciinen
of good size off Cape Hatteras, North Carolina, from a depth of about 30 fathoms, by
means of the beam trawl” (155). Coues (49) also records the capture of a single lobster
at Beaufort, North Carolina, in the summer of 1870.

Dr. Wakeham writes that lobsters are abundant around the island of Anticosti
and that a large number of canneries have been in operation on this island for some
years. He says that lobsters are more abundant on the southern side of the island,
and coneludes that this is “due to the fact that the water deepens gradually on the
southern side, while on the north side of the island you go abruptly into deep water.
The lobsters taken at Anticosti and on the north shore of the Gulf are of large size.
This may be explained by the fact that they have not been overfished to the same
extent there as elsewhere. At any rate we do not find any small lobsters in the traps.
The largest lobster that I have seen taken on the north shore weighed 18 pounds.”

Sars (176) considers it remarkable that lobsters on the southern coast of Norway
never become as large as those farther north. It seems to me that the explanation of
this fact is simple, and applies to both European and American species. The northern
parts of the range of the lobster have been the last to be fished, and consequently the
average size is greater than in the south, where the fishery began.

The bathymetrical range varies with the season and is influenced largely by the
temperature of the water. It may be also governed in some measure by the abun-
dance of food and by the reproductive and molting periods.

Lobsters are occasionally seen close to the shore in very shallow water and they
are sometimes even stranded on the beach. This was the case with the large lobster,
weighing upward of 20 pounds, the mutilated shell of which is now preserved in
the land office of Boothbay Harbor Village, Maine (see p. 114). This great lobster
was discovered on the beach of Boothbay Harbor, at low tide, about twenty-five years
ago.

Professor Verrill related to me his experience with a large lobster at Grand
Manan, Maine, in 1859. This lobster, which he thinks must have weighed at least
20 pounds, had established himself so securely under the projecting side of a large
bowlder that it was not an easy matter to dislodge him, even at low tide; but with the
aid of a boat-hook this giant was at last drawn out and captured. When it was finally
taken to the setilement it attracted very little interest, the fishermen saying that it
was worth only a penny, 2 cents being then the regular price of lobsters, whether of
5 or 20 pounds weight. In those days lobsters were never weighed and sold by the
pound.

Lobsters, on the other hand, stray out to great distances from the shore, and have
been recorded on the fishing-banks of Nova Scotia “from the fishing-banks and ledges
of the Gulf of Maine, such as Jeffrey’s Ledge and Cashe’s Ledge, and from the more
southern offshore banks. They have also been taken from the stomachs of cod caught
on George’s Banks.” (Rathbun, 155, p. 787.)

Lobsters are also sometimes driven by severe storms on the beach, where they
perish in great numbers. In March, 1888, thousands of lobsters were washed ashore
on the south side of Marthas Vineyard during a south and southwest gale.

THE AMERICAN LOBSTER. 17

CHARACTER OF THE ENVIRONMENT.

Where there is great diversity of natural conditions throughout the geograph-
ical range of an animal we may expect to find its habits varying in a proportionate
degree. From Labrador to Maine the Atlantic coast is rocky, and often precipitous,
with deep bays and harbors, and with large islands, some like Grand Manan pre-
senting sheer perpendicular walls to the sea. The coast of Maine, in its middle and
eastern sections, is essentially bold and rocky, and diversified to an extraordinary
degree by channels cut by large fresh-water rivers, by long deep inlets, studded with
islands large and small, by bold rocky promontories, and by groups of larger islands
farther from shore, such as the Vinal Haven or Fox islands. These are masses of gray
granite, scarred and cut up by glacial forces into an archipelago of smaller islands,
abounding in long granite basins and inlets, into which pure sea water is driven
with every tide. Thus are formed the most admirable breeding-grounds for the
lobster, for fish, and other marine animals. In the region of Cape Cod we meet with
extensive shoals, which resemble on a smaller scale those of North Carolina. The
northern part of the Massachusetts coast is rocky, while the southern section is
greatly diversified, abounding in submerged ledges, sandy and weedy bottom, and a
ereat variety of bays and channels in the vicinity of the Elizabeth Islands, where
lobsters used to abound until their numbers were depleted by overfishing.

Under the variety of conditions which I have hinted at, we should not only expect
to find lobsters larger and more abundant in some localities than elsewhere, a condition
greatly influenced by the number and persistence of fishermen, but also to meet with
variations in the time of laying and hatching of the eggs, in the season of molting, in
the time when the semiannual movements are undertaken, in color, and in a variety
of other details.

The habits of the lobster as affected by the changes of season and other causes
in the various stages of its life will be deseribed, as we have been able to interpret
them, in different parts of this work. Certain habits, however, are often so closely
interrelated that the mere mention of one requires a consideration of others also.

INTELLIGENCE OF THE LOBSTER.

Since the lobster belongs to a less specialized class than the crab, it is not surprising
to find that its intelligence is of a lower order. Sluggish as it often appears when out
of water and partially exhausted, it is quite a different animal when free to move at
will in its natural environment on the sea bottom. It is very cautious and cunning,
capturing its prey by stealth, and with weapons which it knows how to conceal.
Lying hidden in a bunch of seaweed, in a crevice among the rocks or in its burrow in
the mud, it waits until its victim is within reach of its claws, before striking the fatal
blow. The senses of sight and hearing are probably far from acute, but it possesses
a keen sense of touch, and of smell, and probably also a sense of taste. We have,
moreover, seen that it is quite sensitive to changes in temperature.

All animals which play the part of scavengers have strong powers of scent, and
the lobster is no exception to the rule. This is illustrated by the way in which it can
be enticed into the traps. Thus it is asserted that where traps are set on a trawl
placed across the tide, the catch is greater than when the trawl is set in the direction

F. C. B. 1895—2

18 BULLETIN OF THE UNITED STATES FISH COMMISSION.

of the current, since in the former case the scent, or fine particles coming from the
bait, is more widely diffused. Lobsters are sometimes wary and shy of entering
the trap, and have been seen to crawl about it several times and examine it cautiously
ou 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.

Many facts will be given in the course of this work which illustrate either directly
or indirectly the intelligence of the lobster. 1 will add here only the following account
of a lobster which was kept at the Rothsay aquarium, in England (Nature, xv, p. 415,
March 8, 1877). A flounder was unintentionally left in one of the aquaria, in which
three lobsters were placed. The largest lobster immediately appropriated the fish,
which was then dead, and buried it beneath a heap of shingle, on which he mounted
guard. Five times within two 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.

THE LOBSTER’S POWERS OF MOVEMENT.

The adult lobster lives and feeds exclusively upon the sea bottom, which it never
leaves of its own accord in any considerable degree. In traveling over the bottom
in search of its prey, the lobster walks nimbly upon the tips of its slender legs. The
large claws are extended forward in front of the head, a position which offers the least
resistance to the water, while the two hinder pairs of walking legs, which end in hard
spur-like joints, serve as picks to steady the movements of the animal.. In thus going
about it has the constant aid of the delicate swimmerets, attached vertically to the
under surface of the ‘‘tail,” each of which consists of a short stalk and two very
flexible blades. By the movements of the swimmerets the lobster is impelled slowly
forward without the aid of the walking legs. The branches of the swimming feet are
garnished with long, chitinous set or hairs, to which, as is well known, the eggs in
the female are attached. Thus these appendages are not only natatory, but play an
important part in reproduction, and by their almost incessant beating movements
serve to keep the developing eggs well aerated and clean.

When taken out of the water the lobster can only crawl, in its vain attempts to
walk, owing to the heavy weight of the body and claws, which the slender walking
legs are now unable to sustain. If turned over on its back the animal is usually able
to right itself when out of the water, but not without great effort.. If placed near
the salt water and left to its own devices, it will almost iminediately strike out by the
nearest path for the sea with as keen a sense of direction as the sea turtle will show
when upon land. Its power of crawling on land is, however, limited to short distances,
and the lobster never forsakes the salt water of its own accord and, as has been said,
never willingly leaves the sea bottom.

In exploring its feeding-grounds, where an enemy is likely to be encountered, the
legs which carry the long claws are extended forward in front of the head, or carried
somewhat obliquely, their tips resting on the bottom, and the long sensitive ‘‘feelers”
are waved constantly back and forth to give warning of any foe or other objects which
the eye may fail to detect. These are exclusively organs of touch. If the anticipated

THE AMERICAN LOBST2R 19

enemy makes his appearance or if the animal is surprised, as when it is suddenly
touched with the blade of an oar or cornered, it will immediately strike an attitude
of defense. It now raises itself on the tips of its walking legs, and lifts its powerful
claws over the head after the manner of a boxer, and strikes with one of its claws at
the offending object, trying to crush it or tear it in pieces. [have several times pulled
lobsters partially or completely out of their burrows with an oar. You have only to
thrust the oar-blade into their holes, when, if a lobster is present, it will immediately
seize if with a firm grip; but it often shows its intelligence by relaxing its hold before
becoming completely exposed. By far the most powerful organ of locomotion in the
lobster is its “tail.” By the flexion of this, aided by the extended tail-fan, the animal
is able to shoot backward through the water with astonishing rapidity, sometimes
going, according to one observer, 25 feet in less than a second. If tossed into the water
back or head first, the animal, unless exhausted, immediately rights itself and, with
one or two vigorous flexions of the tail, shoots off obliquely toward the bottom, as if
sliding down an inclined plane.

The lobster, though less active and keen-witted than the higher crabs, can not be
regarded as a Sluggish animal in any sense. In the water its movements are graceful ;
it is wary, resourceful, pugnacious, capable of defending itself against enemies which
are often larger than itself, and, if the occasion requires it, of running about with the
greatest agility and speed.

On calm evenings in summer at about sundown I have seen lobsters very close to
shore lying on little patches of sand, surrounded by eelgrass, probably waiting their
opportunity to seize a passing fish or crab. If approached in a boat on such an occa-
sion, they soon become aware of your presence and put themselves in an attitude
of defense, but press them too close, or attempt to pin them down with an oar, they
immediately dart backward into deeper water among the seaweed. If still pursued,
the lobster rises and flies in another direction, thus zigzagging its way over the bottom
until it finds safety in some denser tangle or rocky crevice.

Of the English lobster, Travis remarks:

In the water they can run nimbly upon their legs or small claws and, if alarmed, can spring tail
forward to a surprising distance as swift as a bird can fly. The fishermen see them pass about 30 feet,
and by the swiftness of their motion suppose that they go much farther. Athenzus remarks this
circumstance, and says that incurvated lobsters will spring with the activity of dolphins. When
frightened they will spring from a considerable distance to their hole in the rock, and, what is not less
surprising than true, will throw themselves into their hole in that manner, through an entrance barely
sufficient for their bodies to pass; as is frequently seen by the people who endeavor to take them at
Filey-bridge (191).

When a lobster is surprised it seems to disappear with asingle leap or bound as a
locust or grasshopper might do. This habit, added to their appearance, explains why
lobsters were called by Pliny and the ancient writers locuste, or “locusts of the sea.”
The lobster, however, never rises more than a few inches or at most a few feet above
the bottom, and it is evident that swimming at the surface would be impossible on
account of the great weight of the body. The ‘traveling lobsters,” or ferd-hummer,
which Norwegian fishermen, as Sars tells us (176), have described as swimming at
the surface of the ocean in large schools, often many miles from the coast, were,
without doubt, some large species of surface-feeding shrimp.

Lobsters kept in an aquarium often thrive well, and will live for a loug period if
they are properly cared for. In the hatchery of the United States Fish Commission

20 BULLETIN OF THE UNITED STATES FISH COMMISSION.

at Woods Hole, Massachusetts, sea water is kept running through the tanks, in the
larger of which we lave kept lobsters and watched their habits for several months at
atime. If the tank is provided with a pile of stones the lobster very soon investigates
this with care, seeking out the most attractive holes. If several individuals are
placed in the same aquarium, each will select its own hole or corner over which it
establishes a sort of proprietary right. In these they lie during the greater part of
the day with their antenne and a part of the body and large claws projecting, ready
when a good chance offers to strike at a fish, or if an enemy should approach, to retire
at a safer distance into their retreats. If the occupants of the same aquarium are of
about equal size, and if they show no weakness, they usually live in peace; but if one
has been disabled in any way, as by the loss of a claw, he is attacked by the strong
and forthwith destroyed.

As the lobster lies in its corner of the aquarium—always with its tail folded, if a
female “in berry”—it slowly sweeps the water with its long, sensitive antennee, which
it now holds erect, now lowers until they lie horizontal and extend almost directly in
front of the body. The smaller pair of antenne are elevated, while the larger outer
branch of each is constantly beating with a slight up-and-down movement; this branch
supports the delicate filaments which have been regarded as the terminal organs of the
senseof smell. If one watches this lobster he may see it deliberately lower the branches
of the first pair of antenne and clean them by drawing them through the bunches of
stiff bristles of the third pair of maxillipeds, the large prominent appendages which
project forward at the sides of the mouth immediately in front of the chelipeds. The
large claws are held in readiness for use, their tips resting close together on the bottom
and their opposite ends raised obliquely upward.

PERIODICAL MIGRATIONS AND THEIR RELATION TO CHANGES IN THE
ENVIRONMENT.

The adult lobster never moves up and down the coast like the migratory fishes,
but is of a far more sedentary disposition. In the spring months of April and May,
however, large numbers appear to move from deeper water toward the shore. In the
fall they retire to deeper water again.

The movements of such anadromous fish as the mackerel and the menhaden are
influenced by the spawning period, by the temperature conditions, and by the abun-
dance of food. The mackerel is said to thrive in a water-temperature as low as
40° F. or even less. The same causes, of which the influence of temperature may
sometimes be the most potent, probably determine the migration of both fish and
crustacean.

When the question of food is paramount, the lobster will remain in considerable
numbers in the relatively shallow water of harbors, but only on a rocky bottom, where
food is most abundant. The extent of the migration is also naturally influenced by
the depth of the water and the general character ot the bottom, being more extended
on a gradually sloping bottom where deep water is less readily accessible. The exact
period at which the semiannual migrations of the lobster occur varies at different points
on the coast and also at the same point for different seasons.

In the vicinity of Rockland, Maine, and to the eastward as far as Eastport, the
summer fishery begins in the latter part of May and lasts until the first of November,

THE AMERICAN LOBSTER. 21

During this time, lobsters are caught in from 3 to 10 fathoms of water. Tor the rest
of the year the winter fishing is conducted in 35 to 40 fathoms. In general, the spring
migration along the entire coast of Maine and in the Maritime Provinces is accom-
plished in April and May, and the fall movement into deeper water in October and
November.

When the spring is late and the water cold, the lobster keeps away from the shore.
Thus the spring of 1884 was a month later than usual in Prince Edward Island, says
the inspector of fisheries in his annual report (56), ‘ and the ice hung long about the
coast.” ‘The first lobster was caught on the 3d of June. “The hands about the
factories had been idle for fully four weeks, but the first batch or run of lobsters came
in quite as fast as they could be utilized. I have noticed this to have been the case in
previous years, as if when ice remained long the lobster congregated in large bodies
on the outer edge of the frozen belt ready to run for the shore as soon as it was clear
and the temperature suited. Subsequently the batches fell off to a little less than the
average.” Ice is said to remain so long on this coast that few lobster fishermen begin
work until the first or second week in May. In 1892 the ice left early, and some lobsters
were landed on the north side of the island the 29th of April. Packing was begun
as early as the 10th of May. (I*ishery Statements, 1891, p. 97.)

At Cape Breton, in late seasons, very little lobster fishing is done before the 1st
of June, or even later. Lobsters probably do not, as a rule, move in schools, but
approach and leave the shores gradually with the change of temperature, yet asudden
cold snap seems to cause them to disappear promptly from any locality. It is probable
that their disappearance under such circumstances may be explained by their burrow-
inginthemud. (See pp. 26and 29.) Mr. M. B. Spinney, of Cliffstone, Maine, informed
me that in May or June in 1869, at Prince Edward Island, while sailing in a small boat
from Georgetown into Grand River, lobsters were seen for the distance of several
miles crawling over the bottom in very large numbers and often very close together,
the water being 10 or 12 feet deep.

Mr. Adolph Nielsen writes, in reply to certain questions, that as the coast of
Newfoundland is affected by the polar current, a spurt of northeast and easterly
winds often brings down the temperature of the water, and this causes the lobsters to
move off into deeper water or bury themselves in the sand or mud in the midst of
the season. At such times the fishermen can not take them in their traps.

The sudden appearance of lobsters in the spring in relatively shallow water lends
color to the supposition that they sometimes move in large numbers together. Thus,
Mr. A. C. Smith says that in 1884 the proprietor of a lobster factory in New Brunswick
“set his traps on the 20th of April, keeping them baited, but caught nothing till the
night of the 5th of May, when the lobsters suddenly ‘struck in’ as plentiful as at any
time of the season.” :

It is certain that lobsters do not indulge in any considerable northward or south-
ward migrations. This is proved, as Rathbun has pointed out (158), by the depletion
of the lobster fishery at.certain points on the coast, as at Provincetown, Cape Cod,
Massachusetts. He states that the fishery was begun here in 1800, and that between
1845 and 1850 New York City received nearly its entire supply of these crustaceans
from the Provincetown region. A marked decrease in their abundance was noticed
in 1865, and this was followed by a gradual annual diminution, until in 1880 there were
but eight men engaged in the business. If there were any considerable coastwise

22 BULLETIN OF THE UNITED STATES FISH COMMISSION.

migration, it is evident that regions once depleted would in time be restored naturally
by accessions from neighboring sections. This does not appear to be the case, and
we may look upon each geographical region on the coast as inhabited by a distinct
school of lobsters, which hold their ground fairly constantly, so that if their numbers
are depleted by overfishing they would under natural conditions be stocked but
slowly. If this argument is sound, and it certainly looks as if the Cape Cod region
were a case in point, it must follow that the young are not widely distributed, but I
can hardly accept this as probable. It would seem as if the young, which, to be sure,
have little powers of locomotion, would always tend to find an extra local distribution
by tides, winds, and currents. Furthermore, if this were the case, it would follow that
restocking under natural conditions is a slow process at best. Writing iu December,
1885, Rathbun says (158):

The Cape Cod lobster fishery has been at a low standing for many years and, although but few men
have engaged in the fishery of that region for a iong time, there are, as yet, no signs of improvement.

That lobsters move up and down the coast to some extent is inevitable, although
such a migration may be regarded as accidental rather than deliberate or instinctive.
They may also return suddenly, as some believe, to places where they have not been
seen for years. Thus a correspondent wrote to the United States Fish Commission
from South Amboy, New Jersey, February 15, 1886, that lobsters had made an appear-
ance there after an absence of about twelve years. ‘I discovered them late in October,
and captured a hundred before the cold weather set in, after which I could not catch
any.” (Bull. U.S. F. C., vol. vi, p. 407.) Statements of this kind must, however, be
received with much caution, since what appears to be a sudden arrival may be due
to desultory observations.

The subject of the schooling of lobsters is one about which it is very difficult to
get accurate information, and we need to use much caution in drawing conclusions
from too slender data. The only region which I have been able to study for a number
of consecutive seasons is that about Woods Hole, Massachusetts, including Marthas
Vineyard, No Man’s Land, and the Elizabeth Islands, and I will give in some detail
the observations which I have been able to make in this limited area, believing that
they will shed some light upon this interesting and perplexing question.

The fishermen of a part of this region set their traps from the last of April to the
middle or last of June on rocky bottom in the vicinity of Gay Head and No Man’s
Land, while from the middle or last of June until September they generally fish upon
the sandy bottom of the Sound in much shallower water. A few lobstermen fish
during September upon the rocks. ‘They distinguish “rock lobsters” from what they
call ‘school lobsters.” The latter are also called ‘‘sand” or ‘June lobsters,” and are
considered more migratory than the “rock lobsters” or ‘“ground-holders.” ‘‘School
lobsters” are most abundant in summer from the middle of June to the middle or last
of July on a sandy bottom in Vineyard Sound in 5 to 10 fathoms of water.

On June 28, 1890, I found the fishermen at Menemsha! setting their traps both off
Gay Head on a rock bottom and on the sandy bottom of the Sound. The difference

‘Menemsha is a small fishing settlement in the town of Chilmark, Marthas Vineyard, about 2
miles due east from Gay Head, on Vineyard Sound. Gay Head, the remarkable promontory forming
the western extremity of Marthas Vineyard, is 14 miles southwest of Woods Hole Harbor and 6 miles
north of No Man’s Land.

THE AMERICAN LOBSTER. 23

in the lobsters caught at the same time under these conditions was sufficiently marked
to attract attention. The lobsters captured on the rocks had hard shells and frequently
bore old eggs, while those taken in the Sound had in no single instance, up to this
time during the season, borne external eggs, either old or new, and a large number
of them had soft shells. These are often called “paper shells,” or ‘buckle shells,”
the shell being relatively soft, so that it is easily compressible with the thumb and
finger, and the colors are very bright, showing that they have molted within four or
five weeks. Special care was taken to save all egg lobsters caught, since the United
States Fish Commission purchased them for use in its hatchery. These “buckle shells”
or “school lobsters” were said to appear rather suddenly about the middle of June or
first of July, and to retreat into deeper water during the first half of September.

On the 9th of July I again visited Menemsha, and found that since the first of
the month only six lobsters with old eggs had been obtained. These were caught in
the Sound, where the majority of all lobsters now taken had soft shells. On the 16th
and 28th of July, when I made further visits to the locality, the fishery was conducted
almost wholly in the Sound. At the later period the fishermen had begun to shift
their traps to slightly deeper water, following up the lobsters in their retreat from the
shore. On the 11th of August they were fishing both in Vineyard Sound and off Gay
Head in 8 to 15 fathoms. <A large proportion of these lobsters taken in the Sound had
soft shells, but an examination of the ovaries of the soft-shell females proved beyond
a doubt that they had hatched their old eggs and molted during the present season.

Some very interesting facts have been brought out by the record of the fishery at
No Man’s Land during the months of May and June, 1894. Mr. Vinal Edwards found
that egg-lobsters of large size could be taken there in abundance, and accordingly
the Fish Commission drew the supply of eggs for its hatchery from that place. Mr.
Edwards carefully recorded the catches of the smackmen, examining nearly every
lobster himself. The result is given in table 1. The traps were set on ledges of rock,
15 miles from land, in about 15 fathoms of water. Besides the extraordinary dispro-
portion of the sexes—only 6.4 per cent of males being obtained out of a total of 1,318
lobsters captured in May—we notice the equally remarkable and probably correlated
fact that 63.7 per cent of the total number are females with eggs soon to be hatched.

TaBLE 1.—Record of lobsters caught off No Man’s Land in May, 1894.

L@yieMl Gail. = eo cee ee sonaasseeopseeDEeoEe 1,318 || Percent of females with eggs.-.--.-..-.--- 63.7

HemalesiwitheCes tes. secs a joer eee 840 | Percent of females without fF 93) ciao cae 29.8
Females without eggs..----......------. CREE I) Bete CAO EIS E 6 neo ob eece coe sosoecene 6.4
IMAL eS os baesessaais cae neacnoeecesecwesocls Sdn |Pencentiotetomalestaeeeteeeteseeee reese 93.5

' Another striking fact which the fishermen noticed was the persistence with which
the lobsters at this time of the year clung to the rocky areas. When set on a rock
bottom the traps were certain to catch lobsters in abundance, but when sunk upon a
sandy or muddy bottom, though but a few feet away, not a lobster was trapped. In
fishing on trawls, where a long line of traps was put out, it sometimes happened that
some of these would strike a sand bottom, often not more than a narrow streak or bar,
but they were always found empty. Mr. Edwards systematically fished for lobsters
in Woods Hole Harbor from December, 1893, to the June following. He found them

24 BULLETIN OF THE UNITED STATES FISH COMMISSION.

in the winter months abundant on the rocks, but when the traps were placed on the
mud not a lobster was taken.!

The disproportion of the sexes noticed at No Man’s Land is due, I believe, to the
fact that the females find it more advantageous to remain on a rocky bottom while
they areencumbered with their old eggs. As soon as these hatch, the female lobsters
press on in large numbers toward the shore, coming up into the sounds and bays and
on to sandy bottoms during the summer. The lobster can probably protect herself and
eggs better while on the rocks, but almost immediately after the hatching of the eggs
the molt occurs, for some time after which the female is helpless. Now the molting
lobster seems to prefer the sandy bottom while in this eritical state, probably
because it can shield itself better from its enemies. On the sand the molting lob-
ster may hide in tangles of seaweed, or scratch a hole and partially bury itself, as it
often does, and remain tolerably secure, but let the soft lobster try to conceal itself
among the rocks, and whatis the result?) There are hosts of bottom-feeding fish which
haunt the rock-piles, none of which are probably more troublesome than the cunner,
which can go almost anywhere, and would soon surround the soft lobster in its retreat
and nibble at its legs, or snip off its eyes, which means death. The cunners, eels, and
other fish may attempt to pick off the eggs, but these are on the under side of the body
and except in extraordinary cases, where the ova are excessively numerous, the lobster
can fold them between the segments of its tail and thus rest tolerably secure (see p.
34). This theory is supported by the fact that the “school lobsters” caught on the
sand bottom of Vineyard Sound rarely have old eggs and very commonly possess
soft shells. Rocky bottoms furnish food in greater abundance, at certain seasons,
which explains their preference for these areas in winter. Where on the other hand,
as in the region about Provincetown, Cape Cod, the bottom is uniformly sandy, the
lobster has little or no choice of environment.

To sum up the preceding observations, what seems to take place at the western
end of Vineyard Sound during the season of migration is as follows: The general
movement of lobsters toward the shore is here modified by the fact that lobsters with
old eggs find it advantageous to remain on the rocky ledges until the young are
hatched, while the males press on in their inward movement. After the hatching
period the females make their appearance in large numbers in the Sound toward the last
of June or first 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, putting them down 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 keep them there 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 be borne in mind also 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

‘Speaking of the lobsters captured in February, Mr. Edwards says: ‘‘The lobsters taken this
month have been caught on rocky bottom in five lobster pots. I have set five others in deep water on
sandy bottom, and also on the mud, but find none. TI have tried in shoal water in eelgrass, but there
are none there. -I also tried for them in the middle of Vineyard Sound and in Buzzards Bay, but
found none.”

sil

THE AMERICAN LOBSTER. 25

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 pointed out, it is by no means general and is probably more
pronounced in cold than in mild seasons.

TABLE 2.—Showing the monthly mean temperature of the ocean at Woods Hole, Massachusetts.

§ Computed from daily observations of temperature of bottom, taken at high water, 2

at United States Fish Commission Station, by Vinal N. Edwards. 5
Time 1889 1890 1891 1892 1893, | Means
: ie a a vas “Y* 1889-9
F. F. oF, F. 1 OF oF,
DANNOIA, cansaddessoeqoandcansosessoasce 36.9) 38.8] 33.0] 36.8] 29.5] 35.0
| ISG AT See aot on Seen eieesonoccoodess 32. 1 39.9 34.7 31.2 29. 7 33.5
WIEN = ceonmedcodsandopnecedounesopsooc 35. 6 36.6 35.3 33. 2 82.5 34.6
J\j MN a = oe doce soot aeessecesnossscascdd 42.7 43.2 44.3 42.6 40. 0 42.5
WiGhy tase ssonobodeemeses dacceaceeeeernos 5d. 6 53. 2 52. 4 51. 0 byl 74 52.7
(MPP) cesecocseoncacadoeoGeentncSScennde 63.3 62. 0 61.1 62. 1 61. 2 62.1
OO Wares secede sane ene eas eines siecle 68.7 69.3 64.8 68. 0 69.5 68.1
EXUREGY oo cmaqneoanedoaqgontonooeso aeons = eetOnG lak 70.9 1B} OMS Tne:
September ass scene. sae een oo 67.1 | 68.5 61.1] 66.9 67.5 | 66.6
OGtOD CNR e seacoast eine -eoaiseaincs ne 55.3 | 59.0 59. 6 58. 6 60.5 58.6
IGN CHa? Cees Sos scene aesenecaaeamooos 49.9 48.0 47.4 48.3 52.4 | 49.2
MEcembenseese erase cee eater ele seca 43.0 36.7 | 315) 37. 2 40.9 | 40.2
WG ahy mG SoeecostoanecesacougdD 51.7 52.2 | 50.6 50.8 BS ooenoce

The mean temperature of the water at Woods Hole, Massachusetts, was 52.68° F.
for May, from 1889 to 1893 (vy. table 2), the extremes of monthly averages varying from
51° in May, 1892, to 55.6° in May, 1889, and the range was similar for the latter part of
October during the same period. The greatest heat is reached in August (70.6°, 1889,
to 73.3°, 1892), while the temperature of the water in September is but little lower
than that of July. In the latter part of October the water becomes cooled to
about the same degree it had reached during the latter half of May. We may
therefore conclude that the optimum temperature for the lobster lies between 50° and
60° F. When the temperature of the sea water marks 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 the fall, when the temperature 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
which has already been emphasized; so it is certain that temperature is not the only
influence at work in directing these semiannual movements. The question of food
may be of equal or even greater importance.

The winter catch of lobsters in relatively shallow water is often considerable.
Thus, on December 13, 1888, Mr. Edwards set two lobster pots! in the harbor of Woods
Hole, in about 25 feet of water, and hauled them fifteen times during the month,
taking an average of 15 lobsters to a haul, or 223 in all. In December, 1889, 54
lobsters were taken in a fyke net at the head of the harbor, 36 were captured in
January, while none were caught in February.

In December, 1893, Mr. Edwards began to collect more systematically facts relat-
ing to the winter habits of the lobster, the results of which are discussed in another
place (see pp. 30,31, 44, 45, 79, 80). Five traps were set in the harbor of Woods Hole
in 25 to 29 feet of water on rocky bottom (it being impossible to get any lobsters on the
mud); 224 were taken in December, 501 in January, 246 in February, and 348 in

'In these and all other traps used, the space between the laths varied from 1 to 1? inches,

26 BULLETIN OF THE UNITED STATES FISH COMMISSION.

March. Only 6.1 per cent of the total catch were egg lobsters, and while this number
would have been increased if the traps had been scattered instead of kept in definite
spots, it would contrast markedly with the results at No Man’s Land, where more than
half of the total catch were lobsters with external eggs (table 1).

In severe winters lobsters are driven into deeper water or forced to protect them-
selves by burrowing in the mud. The effect of sudden or extreme cold upon these
animals may be witnessed in lobster pounds, where they are kept in large numbers
to supply the winter market. On the Vinal Haven Islands, near Rockland, Maine,
there is a large pound belonging to Messrs. Johnson and Young, of Boston, of 12 to
15 acres in area. It is said to have an average depth of 18 feet at low water. In
January, 1893, during a cold snap, ice was formed over this pool to the thickness of 31
inches. At this time many of the lobsters died. All the pollock also, which had been
placed in the pond, were killed, some of them being 235 feet long, and large numbers
of hake at the same time succumbed.!

Lieut. W. M. Wood (207), while transporting live lobsters from New York City to
Chesapeake Bay, tried some experiments upon the effect of reducing the temperature
of the water. . Lobsters placed in water at the freezing-point were just alive after
one hour’s immersion. He was of the opinion that lobsters could be kept alive for a
number of days in a cold chest, with a temperature of from 40° to 50° F. The practice
of transporting lobsters by the aid of ice is now generally adopted.

The annual range of temperature thronghout the stretch of coast inhabited by
the lobster is less than might be supposed. The temperature of the surface water of
Winter Quarter Shoal, Virginia, ranges from 35° to 76° F.; at Five Fathom Bank,
New Jersey, the range is 37° to 76°. Delaware Breakwater, which is practically the
southern limit of the lobster, is situated between the light-ships anchored upon these
two shoals. At Sandy Hook light-ship, north of the Five Fathom Bank, New Jersey,
we have an annual range of 33° to 74°; at Bartlett Reef and Hartford Shoal light-
ships, on Long Island Sound, it is 33° to 70°. The middle portion of Vineyard
Sound, farther east, has a similar range, while at the Brenton Reef and Vineyard
Sound light-ships, the region of Block Island, the Elizabeth Islands, and Marthas
Vineyard, the temperature varies from about 32° to 69°. The range at Woods Hole
(see table 2) is about 29° to 73°, taking the means for each month, while the actual
extremes are greater. At Pollock Rip light-ship, at the southern end of Cape Cod,
the mean range is 52° to 62°; in the Gulf of Maine the same range is obtained by
combining the results of observations at all stations. In some places the maximum is
only 54°. The preceding data are extracted from a paper by Mr. Rathbun (157).

Mr. J. H. Duvar says that from 1878 to 1880 the average temperature on the north
shore of Prince Edward Island was 56.56° in June, 63.40° in July, and 62.27° in
August. The temperature of the water at bottom in 6 to 8 fathoms he estimated
roughly at 55°. Lobsters spawn in July on the north shore; in August on the south

1The inspector of fisheries of Prince Edward Island has an interesting note on the capture of
lobsters through the ice in his annual report for 1882 (270). He says that on March 10 of that year
there were brought to him ‘‘a number of lobsters of a uniform length of body [probably meaning
carapace or shell of the back] of 4 inches, and one weighing 35 pounds that had been taken through
the ice by the scoop of a mud-digging machine in a creek off Cascumpeque Bay. They seemed rather
sluggish, but not torpid.” It is evident that these lobsters preferred to burrow in the mud rather
than migrate into deeper water.

THE AMERICAN LOBSTER. PAL

shore. This is explained, he thinks, by the current and by the rise of the tides in the
straits of Northumberland, which make the southern water cooler, aud hence delay
the spawning (209, p. 233).

Nielsen finds that the temperature of the water along the coast of Labrador ranges
very low and does not exceed 46.05° I, on the warmest summer days. ‘The lobster is
thus debarred from this coast north of Henley Harbor, where it comes inore directly
under the influence of ice and the arctic current (see p. 15).

SENSIBILITY TO LIGHT.

The lobster is essentially a nocturnal animal, exploring the bottom in the quest of
food mainly in the night, when it is far more active than during the day. This can be
proved by anyone who watches their habits in aquaria or in lobster ponds or cars. It
is true that they show some activity in the daytime, especially if they are fed, but at
night they become very restless. Moving nimbly about, they explore every part of the
car or investigate anew the resources of the aquarium. I believe that the eggs are
laid and that the pairing takes place at that time, and this inference is strengthened
by the fact that this is the common habit of shrimp and many other crustacea. The
crayfish, according to Chantran (37), usually lays its eggs in the night.

According to Forel, light can not penetrate in the ocean below a depth of 400 meters

of tolerably clear water, but even in 50 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 bottom, which lobsters frequent in summer, and where we
mnay expect to find the greatest difference between their diurnal aud nocturnal habits.
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 and succumbs in a short time.
F The large floating cars in which lobsters are generally stored alive, 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 always suffer and sometimes die in
consequence. The majority of lobsters probably spend the greater part of the year
in depths where the effect of sunlight is but very 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 the adults would avoid intense sunlight
The effect of light upon the colors of the shell is considered in another place. (See
pp. 135, 136.)

DIGGING AND BURROWING HABITS OF THE LOBSTER.

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 at least, as
extensively as the muskrat. I have observed this interesting habit only in lobsters
confined in pounds where they are obliged to adapt themselves to new conditions, it
is true, but since they burrow while in these inclosures in summer as well as in winter,
we may infer that the habit is one which is often practiced when the animal is free to
roam at will. This has been observed, moreover, by fishermen who have frequently
taken lobsters from their holes.

28 BULLETIN OF THE UNITED STATES FISH COMMISSION.

The lobster pound at the Vinal Haven Islands is a granite basin with a clay or
mud bottom, and with low mud banks in certain parts of the shore. At low tide it
has an average depth of 3 fathoms, while the difference between tides is 10 feet. On
the 26th of August, 1893, I explored this pound in a boat, in company with Mr. Thomas
Barton, an intelligent lobster fisherman, and had an excellent opportunity to observe
how lobsters behave under such conditions on a bright summer afternoon. It was
quite common to see these animals partially buried in the mud in shallow water,
their antennie, eyes, and part of the shell projecting from the muddy surface. We
could rely upon finding lobsters in the holes which they excavate beneath stones, and
rarely failed to discover one or more individuals in every good-sized chink among
the rocks. Others lay at the mouths of burrows which they had dug straight into the
banks. Comparatively few lobsters were seen lying upon the bottom or crawling
actively over it. Occasionally two or three lobsters could be dislodged from a common
place of retreat, and Mr. Barton said that in the spring, when the ice was breaking up,
he had taken five lobsters from a single hole in the mud. Some years ago the lobsters
made their way out of this pound, as I was told by an old fisherman formerly employed
there, by excavating a submarine passage beneath the dam. In order to effect their
escape, they had dug down beneath the stones to a depth of from 2 to 3 feet.

At one of the pounds in Southport, Maine, I had a still better opportunity to
study the burrowing habits of the lobster. The larger pound at this island is under the
charge of Mr. A. P. Greenleaf, a man of much experience in fishing the lobster and
a very intelligent observer of its habits... He finds that the lobster burrows most
extensively in winter, when it is far less active in the pounds than at other times.
When the water is drawn off from the pound in winter the lobsters often remain in
their holes, the mouths of which are then exposed along the banks, but in summer
they are more careful under these conditions to forsake their burrews and crawl into
deeper water.

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 I have
no observation in support of this latter supposition. In some cases, however, I have
noticed the under side of the tail-fan to be scratched and scarified and the marginal
fringe of hairs worn down in such a way as to suggest the probability of such a use.’

That lobsters transport stones with their large claws, Mr. Greenleaf had the oppor-
tunity to observe, while watching a lobster one day in the pound. The animal was
maneuvering about a hole, in 3 feet of water. It was seen to crawl up to the burrow,
possibly one which had been dug by another lobster, and cautiously put in first one
claw and then the other. Finally it went in so as to conceal about half the length of

'Mr. Greenleaf is the only fisherman whom I have met who has independently determined the
period during which the female lobster regularly carries her eggs.

?The process by which the hole is said to be excavated solely by means of the tail has been
described by a writer on the habits of the lobster (787). This paper abounds in errors, and leads one
to suspect that the author has drawn too largely upon the accounts of others; still, this fact need not
discredit this particular observation. He says: ‘‘The tail is slowly drawn up at first, taking as much
of the mud as possible on its under side; then, when well under the body, a final powerful jerk sends
the mud or sand from out in front, and at the same time draws the lobster farther back into the cavity
thus made, enabling him to get a better grasp for repeating the process over and over again, till by
degrees he disappears from sight.” The statement that ‘‘these holes are for the shelter of the lobster
during the period of exuviation,” however plausible it may be, is contrary to observed facts.

THE AMERICAN LOBSTER. 29

its body and brought out in its large “club claw” a small stone, which it deposited
near the mouth of the burrow. Having thus removed this obstruction, it faced about
and *‘backed,” tail first, into its newly acquired shelter.

The east pound at this place has 18 feet of water at half tide and an average depth
of about 8 feet. On one side are low rocky cliffs, the talus of which gives shelter to
many lobsters, while the low clay banks of the opposite shore are so completely under-
mined by their burrows as to afford, in some places, a very insecure foothold. I
examined these banks carefully from a boat, and had the opportunity of satisfying
myself of the extent to which the tunneling operations had been carried on. The holes
were driven horizontally into the mud bank to a distance of from 1 to 5 feet, and in
each a lobster could either be seen, the tips of its large claws and its antennie standing
out, or could be felt by inserting the end of an oar, the lobster fixing its large claws
on the blade and sometimes allowing itself to be dragged out clear.

The holes had sometimes a relatively large opening of 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
swerve to the right or left, which is explained, perhaps, by the presence of some obstacle
in the path. In some cases the holes were made beneath rocks, and the entrance was
often much larger than that described, owing, perhaps, 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 is exceptional to see a lobster with its tail projecting from the burrow. I saw one
or two under these circumstances, and when touched they immediately disappeared.
I thought that possibly they might be engaged in digging while in this position, but
this was evidently not the case, as the water about the hole was very clear. These
pounds are often much roiled, so energetically do the lobsters turn over the bottom
and dig into the banks. On this account it is not easy to watch the process of
excavation, which in all probability is carried on at night.

I was informed by one fisherman, who had hunted lobsters quite extensively along
the north Atlantic coast, that he had frequently taken lobsters out of holes in the
mud and eelgrass, while wading in shallow water. lt has been observed in pounds
that a cold snap in winter will cause the lobsters to burrow suddenly in the mud, so
that they can not be taken in traps for several days. We have already noticed the
probable occurrence of the same thing in Newfoundland, when the temperature of the
water is abruptly lowered. (See pp. 21, and 26, note 1.)

The burrowing habits of certain species of crayfish are well known, while those
of the Stomatopods, which have been described by Professor Brooks, (265) are equally
characteristic. We meet with the same habit in many shrimp, such as Alpheus,
expressed in a greater or less degree; in crabs, and in a great number of the lower
crustacea.

THE FOOD OF THE LOBSTER AND HOW IT IS PROCURED.

The food of the lobster consists principally of fish, alive or dead, and of inverte-
brates which inhabit the bottom and come within its reach. It is not unusual to find
bits of algze, such as the common eelgrass, in its stomach, aud sometimes in such
quantities as to show that it is not an accidental occurrence. Vegetable matter,
however, forms, at most, but a small part of its diet. Fragments of dead shells are

30 BULLETIN OF THE UNITED STATES FISH COMMISSION.

frequently met with, and in lobsters from 3 to 4 inches long, under very peculiar cir-
cumstances. (See pp. 89 and 90.) Coarse sand and gravel-stones, occasionally as large
as duck shot, may also be found in the stomach, but with no marked regularity.
These are not necessary for grinding the food, as in the gizzards of fowls, since the
walls of the lobster’s stomach are furnished with an admirable masticatory apparatus;
still, whether of accidental occurrence or not, they can hardly fail to serve a useful
purpose.

In the course of this investigation of the habits of the lobster, the stomachs of
large numbers of these animals were carefully preserved during a period of seven
months (December to June). They were all captured in the harbor of Woods Hole,
Massachusetts, under the conditions described on p. 25. <A considerable number
of these stomachs were empty; more than half contained remnants of recently devoured
fish, a mass of scales and bones, mixed with fragments of the indigestible parts of
other organisms. In many cases it was quite evident that the bait of the traps
formed the only food found in their stomachs.

The lobster undoubtedly regurgitates the insoluble and indigestible parts of
its food. That the crayfish possesses this power was shown by the experiments of
Lemoine (178). When the buccal cavity was stimulated by electricity, antiperistaltic
movements were set up in the remaining parts, until the contents of the stomach
escaped by the mouth. It was thus proved that the esophagus was capable of two
kinds of movements—peristaltic and antiperistaltic. Some such outlet for waste
matter is absolutely necessary in an animal where the fluid or finely divided and
digestible parts of the food only can pass into the delicate intestine. The hard parts
of fish, mollusks, and crustacea appear to be retained until they have given up a good
deal of their lime, thus contributing to the calcareous supply of the exoskeleton.

The stomachs examined contained remnants of the following organisms placed in
the order of their relative abundance: fish (procured independently of the traps);
crustacea, einbracing chiefly isopods and decapods; mollusca, consisting largely of
small univalves; algz; echinoderms and hydroids. The bones of fish showed them
to belong, as a rule, to small individuals or species. Among the crustacean remains
parts of the small mud-crab, Panopeus (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, often in large numbers. This species is a scavenger, and
devours the bait used in the traps, which explains its common occurrence in the
stomachs of lobsters recently caught. In one ease, that of a female captured in January,
the stomach was filled with fresh lobster eggs in an advanced stage of development.
These were not taken 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 outside enemies, 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 species are swallowed entire, and afterwards pulverized in the
gastric mill. Hchinoderms probably enter largely into the diet of the lobster, wher-
ever they abound. Parts of the common starfish (Asterias forbesii) and rarely a few
spines of the sea-urchin (Arbacia punctulata) were detected, but it might be that the
latter were swallowed together with other calcareous fragments. Very little change

THE AMERICAN LOBSTER. sil

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 the cold weather,
yet it is probable that food is less abundant and less necessary in winter. (See pp.
24, note 1, and 25.)

That lobsters catch fish alive there is no doubt, but few have ever seen this feat
performed. Fish which inhabit the bottom, like the flounder, would naturally fall an
easy prey to their powerful claws. They are said to catch the sculpin, and I have
known a lobster which was confined in an aquarium at the United States Fish Com-
mission station in the summer to seize and devour the sea-robin (Prionotus evolans).

The common blue crab ( Callinectes hastétus) is said to capture fish, and fishermen
report having taken haddock on trawls with the heads almost nipped off, as if cut by
the claws of the lobster.

The smaller of the large claws is essentially a pair of toothed nippers, the hard
tips of which are incurved so as to enable the animal to secure and hold every
object which it can fairly seize. This is sometimes called the ‘fish claw ” or the ‘quick
claw” by fisbermen in Maine, while the heavy crushing-claw is called the ‘club claw,”
and according to Travis (191) it was known in England in the last century as the
“knobbed” or *‘numb claw.”

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 the shark is occasionally utilized by the Gay
Head fishermen on account of its firmness and lasting qualities.

In the lobster pound at Southport, Maine, the lobsters are fed chiefly upon herring
and seulpin. The fish are scattered around the shore and over the pond. They stop
feeding them after the 1st of December, and the fall stock is taken out for the winter
market in January, February, and March.

In the 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
is there reminded of a pasture in which the soil has been rooted up by pigs. As a fish-
erman 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 eelgrass, or loosened it so that it had
floated to the surface, and cartloads of it had been cast ashore. We have already
seen that 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 conehs,
which live upon hard bottom, in deep water, and devours their soft parts. An illustra-

'T am told by Mr. M. B. Spinney, of Cliffstone, Maine, that many years ago, when lobsters were
very abundant, he and his father used ‘“‘ wash bait” in taking them. Fish, such as the mackerel, were
minced up and put overboard. Then, as lobsters came flocking from all directions about the boat,
they would gaff them.

2 The grass-wrack, or eelgrass (Zostera marina), belonging to the pond-weed family (Naiadacew), is,
with one or two exceptions. the only flowering plant found growing submerged in salt water on the
New England coast.

32 ; BULLETIN OF THE UNITED STATES FISH COMMISSION,

tion 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.

On many parts of the coast the lobster does not find any lack of dead fish for
food. ‘This is notoriously the case where seining is conducted on a large scale, as on
the coast of Maine. One of the great evils attending this method of taking fish is
the destruction wrought upon the young. In seining mackerel the catch is hoisted
upon deck, where the fish are sorted, the larger, which are marketable, being saved
while the smaller fry are thrown overboard. Owing to the rough treatment which
they receive, and especially the exposure to the sun, the smaller fish are thus said to
be destroyed by thousands. The lobsters in the vicinity profit by this evil, playing
the part of scavengers.

Lf a lobster which 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 chelxe 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 fourth 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 mandibles—maxille and first and second pairs of maxillipeds—the meat is as
finely divided as in a sausage machine, and a stream of fine particles is passed con-
stantly into the mouth, being previously submitted to the action of the inandibles.

If one wishes to watch the movements of the complicated mouth parts more
closely, he 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 plate
of the large 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 independently.
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 maxille come together
over the lower posterior half of the mandibles. The movements of the masticatory
parts of the second maxille are synchronous with the beating of the scaphognathite.
These project somewhat obliquely over the convex surfaces of the appendages in front, _
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 outward, with
slight up-and-down movement. The large maxillipeds move together, the toothed
margins meeting like the edges of a nutcracker (compare fig. 68, pl. 30), 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,

Chapter I1.—REPRODUCTION.

THE REPRODUCTIVE ORGANS.

The breeding habits of an animal are not only of great scientific interest, but of
the utmost practical importance, in view of any experiments which we may under-
take in its artificial propagation. When this work was begun the breeding habits
of the lobster were very imperfectly understood, and until now no exhaustive study
of the subject has been attempted. In questions of this kind, one may be led to
draw conclusions from too slender data, since an abundance of carefully attested
facts gathered from a sufficiently wide area can be attained only with great difficulty.

In the summer of 1891 I made as full a study as the time would allow of the
reproductive organs and habits of the lobster at Woods Hole, Massachusetts, and in
the summer and fall of 18931 was able to add to my knowledge of this subject by
materials gathered at different points along the northern Atlantic coast.

The reproductive organs will now be briefly considered, reserving a description of
their structure and development for another part of this paper. (See Chapter X.)

The ovaries, or ‘“‘coral” as they are sometimes called, consist of two cylindrical
rods of tissue united by a transverse bridge in the upper part of the body, and are
immediately exposed upon opening the dorsal body wall. The uniting bridge of tissue
probably represents the first trace of a fusion, which is expressed in various degrees
in ditferent Decapods. The ovarian lobes extend over about two-thirds the length of
the animal, from behind the head to the third, fourth, or fifth segments of the “tail,”
and when approaching maturity are of a rich, dark-green color (plate 36, fig. 123; see
also plate 38). The ripe ovaries are so much swollen that they fill all the available
space in the upper parts of the body-cavity. The bead-like eggs are clearly seen
through the thin ovarian wall, and when this is ent they flow out, if perfectly ripe, in
an uninterrupted stream. When the congested ovary is not nature the loosened eges
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 deep-green color of
the ovary is at once apparent, but since the eggs can not be pressed from the unyield-
ing body of the animal, there is no way of telling when these are ripe short of actual
dissection.

The secondary organs of reproduction in the female are: (a) The oviducts, two short
membranous tubes, which lead from the ovaries to the exterior, and open; one on each
side, upon the basal segments of the second pair of walking legs; (b) the copulatory
pouch or seminal receptacle, for storage of spermatozoa (plate 7, and plate 38, fig. 130),
situated between the bases of the third pair of walking legs; (c) cement glands, which
secrete the material by which the eggs are fixed to the swimming legs (plate 40, fig.
144, and plate 49, figs. 211, 212); (d) the first pair of abdominal appendages, which
are so reduced in size and modified as to be useless for swimming.

I. C. LB. 1895—3

34 BULLETIN OF THE UNITED STATES FISH COMMISSION.

The male reproductive organs are the testes (plate 36, fig. 120), the ducts of which
open at the base of the last pair of walking legs. The sperm which is inclosed in
gelatinous capsules or spermatophores, the secretion of the seminal ducts, is thus
ejected in packets. There is no penis or tubular extension of the integument from the
opening of the duct, as is the case with the Brachyura.

The first pair of legs of the tail are also modified in a peculiar way in the male, as
if.they served for conducting the spermatophores through the elastic, slit-like orifice of
the seminal receptacle.

There are numerous secondary sexual distinctions, the most striking of which is
seen in the abdomen. The latter is conspicuously broader in the female, a variation
which is correlated with the greater size of the ovary as compared with ‘the testis;
its lateral plates are deeper and it is more conspicuously hollowed below to form an
ineubatory pouch for the ova. A discriminative fisherman can thus distinguish the sex
ata glance. (Compare plates 4 and 6.) The large claws are more voluminous in the
male than in the female, and the male attains the greatest size. This would imply
that the male molts oftener than the female, which, according to the observations of
Brook (26), is actually the case.

In addition to these distinctions Gouriet (82) found that in the crayfish the
antenne were longer in the males than in the females; that while the length of the
abdomen of the male was relatively shorter, it was heavier than in the female. He
found the length of the abdomen, compared with that of the carapace, to be in the
proportion of 7 to 6 in the female, while in the male this difference in length did not
exceed ;}5 inch.

In the male lobster the second pair of swimmerets carries a small spur on its inner
blade, the function of which is obscure. The reduction of the first pair of abdominal
appendages in the female is in all probability correlated with their use in reproduction.
If they were of the normal size they would catch so many eggs at the time of oviposi-
tion that it would be next to impossible for the female to completely flex the abdomen.
Locomotion would thus be interfered with, and the eggs would be constantly exposed.
As it is, it sometimes happens in very large females, where the ova are excessively
abundant, that it is impossible to completely fold the abdomen. (See p. 54.)

Each testis consists of a slender, grayish-white, sacculated tube filled with devel-
oping sperm cells (fig. 120, plate 36), and its coiled duct usually contains sperm in
abundance. ‘The spermatophore can be easily pressed from the duct, when the latter is
dissected out. The sperm cells have a characteristic shape (fig. 129, plate 37) and are
absolutely immobile in the conditions under which they are ordinarily observed, but
it is impossible to suppose that this is always the case. Their complicated form,
recalling that of the bell-shaped medusa, leads one to suspect that under the influence
of some subtle and unknown stimulus, possibly of a chemical nature and coming from
the cement glands or some other organ, they are able to execute independent and
rapid movements through the water.!

1Gano states that he once detected amcboid movements in the rayed sperm-cells of the crab
Maia. See observations quoted on p. 49. ;

THE AMERICAN LOBSTER. 35

THE PAIRING OF THE LOBSTER AND OF OTHER CRUSTACEA.

The copulation of the lobster has never been seen, as far as I am aware, in any of
the species, but we know that it takes place in spring and summer at least, if not at
other times of the year. If ripe-females, or females even with newly laid eggs, are
examined in June or July at Woods Hole, the seminal receptacle is found to be almost
invariably charged with spermatozoa, and it is evident that copulation takes place,
certainly in many cases, without immediate reference to the condition of the animal.
Thus on August 19 I examined a female lobster which was 9 inches long and found
her seminal receptacle loaded with sperm. The ovaries were of a light, greenish-yellow
color, and in a very immature condition. This lobster had been impregnated at least
two years before her eggs would be ripe.

Iwas surprised to find the seminal pouch of another lobster, which was examined
about the same time, to be charged with freshiy deposited sperm, although it had just
hatched a brood and was preparing to molt. It therefore seems probable that the
male lobster has no means of discriminating the sexual condition of thefemale. This
lobster, in the ordinary course of nature, would soon have lost in the molt the sperm
with which she had been so recently supplied. The first copulation, which had occurred
either before or shortly after the hatching of the brood, must have been followed by a
second union in order to secure the fertilization of the next batch of eggs. These
would not be due, moreover, until one year from this time. It is thus evident that
the female lobster is not impregnated once for all and compelled to take the chances
of fertilizing her eggs, but is approached more than once by the male. The molting
of these animals, although subject to less variation in the adult female than in the
male, renders this necessary. Females usually molt shortly after the hatching of a
brood. Where the molting is accomplished just before the eggs are laid, which
happens very rarely—I have noticed only two cases in the lobster—(see p. 80), copu-
lation can precede the act of extrusion by a few days at the most.

A lobster which had been kept in an aquarium for upward of two months in the
summer, without access to the male, laid eggs which were normally fertilized. This
and other facts which have just been mentioned show that the female lobster must in
some cases be impregnated more than once before each reproductive period, and also
that the spermatozoa retain their vital activities for a long time, perhaps, as Bumpus
suggests (30), from one to two years. This is not so remarkable, when w:. -onsider
the longevity of spermatozoa recorded by Sir John Lubbock (Weismann’s Essays,
vol. 1, p. 52), who succeeded in keeping a queen ant until she was 15 years old,
during which time she continued to lay fertile eggs. Fertilization must have taken
place at the latest in the season when the insect was captured. ‘There has been no
male in the nest since then,” writes Lubbock, ‘and, moreover, it is, I believe, well
established that queen ants and queen bees are fertilized once for all. Hence, the
spermatozoa of 1874 must have retained their life and energy for thirteen years, a
fact, I believe, unparalleled in physiology.”

Observations on the copulation of the crayfish (Potamobius fluviatilis) have been
made by Gerbe (43), Chantran, and other naturalists. The latest and most detailed

Wrh

account of Chantran, published in 1872 (39), is as follows: !

1In quotations froin works in foreign languages, I shall give, for convenience, the English trans-
lation. The extract can be verified by reference to the original.

36 BULLETIN OF THE UNITED STATES FISH COMMISSION.

The male crayfish deposits its fertilizing matter in the form of spermatophores upon the plates
of the tail-fan and upon the plastron of the female. The time of egg-laying varies from two to
forty-five days after copulation. When the time comes for the extrusion of the eggs, the female raises
herself upon her feet, and then the abdominal appendages secrete for a number of hours a grayish,
somewhat viscous mucus. She thereupon lies upon her back, bends her “tail” toward the opening
of the oviducts, so as to form a kind of cistern or chamber, as described by Lereboullet, into which
during the following night the eggs are received as fast as they are expelled from the genital organs.
This expulsion lasts from one to several hours. These eggs, which are always turned so as to present
their whitish spot or cicatricula uppermost, in order to be fertilized the more readily, are thus found
engulfed in the grayish mucus which fastens, in some degree, the swimmerets and the borders and
extremity of the ‘‘tail” to the thorax. This also helps to bound the pocket or chamber, in which there
is a certain amount of water inclosed with eggs and mucus. Immediately after egg-laying we can
find in the water and mucus spermatozoids exactly like those contained in the spermatophores which
are attached to the plastron, and from which, in fact, the sperm-cells proceed. The spermatozoids are
thus in direct contact with the eggs and are in the presence of a vehicle which assists them to penetrate
the ova. Feeundation is effected in this chamber, that is, outside of the genital organs of the female.

The spermatozoids found mixed with the eggs and mucus in the egg-chamber are like those
found in the spermatophores and male sexual organs. In the course of the first three days after
egg-laying these spermatozoids become spherical, pale, and continue immobile. After this they wither
and become smaller, darker, and more irregular. Finally, when, after the fixation of the eggs, the
excess of mucus has completely disappeared by means of pressure exerted by the incessant contractions
of the abdomen, which takes place in from six to eight days after egg-extrusion, those spermatophores
which still remain attached to the plastron consist of small white coriaceous filaments. The latter
are either isolated or composed of several adhering together. They have nothing to show but a
central cavity, in which the microscope can detect nothing but a few spermatozoids, more or less
withered. The wall of the spermatophores preserves its thickness and remains, as before, composed
of a hard, striated, tenacious mucus.

On the 10th of October a smal! species of Cambarus copulated in an aquarium, in
the following manner: The animals lay on their sides, and the sternal surface of the
thorax of the male was pressed closely against that of the female. The abdomen of
the female was folded beneath that of the male. The male grasped with bis great
claws the large pincers of the female, and thus held her securely, bringing also into
service the walking legs. According to Andrews (Johns Hopkins Univ. Cire., vol.
XIV, p. 74), the spermatophores, which I did not observe, are deposited in the annulus
of the female, and the animals are firmly adherent by means of definite hooks and
ridges on the appendages of the male and female respectively.

The following notes are interesting as showing how popular errors in regard to
the breeding habits of lobsters have arisen. Some of these statements, mixed with a
minimum of accurate observation, have been repeated so many times that they have
almost assumed the semblance of truth.

Travis (191) writes to Thomas Pennant, in a letter on the habits of Homarus gam-
marus, published in 1777, that lobsters ‘“‘begin to breed in the spring and continue
breeding most of the summer; they propagate more humano and are extremely prolific.
Dr. Baster says he counted 12,444 eggs under the tail, besides those that remained
in the body unprotruded. They deposit these eggs in the sand, where they are soon
hatched.” ‘This curious contradictory statement is repeated by Herbst (88), who says
that “they lay their eggs in the sand, where they are hatched by the sun.” !

‘The same notion existed in regard to the breeding habits of crabs. Thus, Herbst says: ‘‘The
sea crabs do not show so much care for their young as the crayfish. They try to deposit their eggs
either on the shore in the sand or they commit them to the sea, which washes these eggs thus extruded
in on the beach, where they are soon hatched by the sun, and the young seek again their proper
element.” Of the land crabs, he says: ‘‘They carry their eggs to the sea, where the females wash them
off from their tails. They are then cast up by the sea on the beach, where they are hatched by the sun.”

————

THE AMERICAN LOBSTER. 3

Boeck asserts (20) in his history of the Norwegian lobster fishery, that a real act of
copulation takes place, the male placing its double male member (modified appendages
of the first abdominal somite) into the outer genital openings of the female, and that
the eggs are impregnated while they are yet in the ovary.

Fraiche (70) says that the union of the sexes takes place in the fall of the year
(October and November) for the common and Norwegian lobsters, and in the case of
the former species extends 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.

He thinks that the seminal fluid is introduced directly into the oviduets, and
says that the sides of the abdomen secrete a viscous substance which incloses the
eges and attaches them to the body of the female.

The question, How is the fertilization of the eggs effected in crustacea? is one
which has been asked by naturalists from the days of Aristotle down to the present
century, and it has received the most varied and contradictory answers. <A_ brief
account of the history of opinion on this subject has been given by Broechi in his
thesis on the male organs of the decapod crustacea, published in 1875 (25). One
source of difficulty lay, as recent studies have proved, in supposing that the process
was essentially the same in both Macrura and Brachyura.

Porzio! and Cavolini (36),' among the older writers, as Brocchi shows, had clearer
ideas upon this question than their immediate successors. Thus the Neapolitan
physician, Porzio, says, in bis study on the lobster:

Organa autem propagationis et generationis sic constructa sunt, ut facilem non inveniam
rationem qua maris semen, in feminie corpus ejaculari, infundi, vel introiri possit.

Cavolini also remarks in his memoir on generation, published in 1787, that—

The crustacea copulate face to face, with the penis on the outside of the body; there is no intro-
mission, for the papilla which we have shown to be present on the base of the last pair of legs can
scarcely serve to make a passage for the semen; the eggs are glued to the hairs of the female and are
bathed in the semen (36).

Milne Edwards (58) in his Histoire Naturelle des Crustacés, published in 1834,
expressed some true ideas upon the reproductive processes in the crustacea which were
not comprehended by many subsequent writers. At the same time he falls into errors
in regard to certain organs and their functions. He says that the first two pairs of
abdominal appendages in the male, which are often so different from the following
pairs, seem to serve as exciting organs in the act of reproduction, but that naturalists
have been mistaken in regarding them as representing the penis. In many cases, as in
Gegarcinus, their size would make it impossible for them to penetrate into the vulva,
and he says “‘ we have proved, by direct observation, that in others it is the lower end
of the efferent canal which is alone introduced into the body of the female.” These
appendages apparently assist in directing the penis toward the vulva, and possibly in
exciting the latter. (See note 1, p.39.) He calls attention to the important fact that
in the Anomura and Macrura there is no copulatory pouch such as he had discovered

1T have been unable to consult the original works of these writers, and give the quotations from
them on the authority of Broechi and Cano,

38 BULLETIN OF THE UNITED STATES FISH COMMISSION.

in the Brachyura. In the Brachyura he found that a trne copulation took place: ‘The
wands of the male penetrate into the copulatory pouches situated below the vulve of
the female, and deposit there the semen, which is so held and preserved in that part
that it may be turned over the eggs as fast as they pass out.” On the coasts of Brittany
Milne Edwards found a female Cancer pagurus, which was fertilized, ‘and in which the
extremities of the wands of the male were broken off after copulation, as happens in
many insects; these organs remained inclosed in the copulatory pouches.” As
Brocchi (25) observes, Milne Edwards seems to have foreseen the presence of sperma-
tophores, for in a subsequent work (59) he says, in reference to this observation, that
since his attention has been directed to spermatophores it has seemed possible ‘that
the sort of stopper in question left in the vulva may have been a body of that nature
rather than a fragment of the penis.”

In regard to the reproduction of.the Macrura, where there is no internal seminal
receptacle, the fecundation of the eggs, says Milne Edwards (58), is less easily under-
stood:

It is generally admitted that in all these animals there is a true copulation, in consequence of
which the seminal flaid is introduced into the interior of the generative organs of the female. If it
were not so, it would be difficult to understand how the eggs, which fill the entire ovary, the first of
which are laida long time before the last are developed, come in contact with this fluid, as a necessary
condition of their fertilization. But there is not, so far as I know, any direct observation which proves
the existence of such a copulation, and the absence of a copulatory pouch leads us to suppose that in
these animals the eggs are fertilized as in the cricket, or very shortly after they have left the body of
the mother. After being received into the cavity of the ovary, the egg is directed little by little
toward the external orifice of one of the oviducts, the walls of which secrete in spring a rather thick,
albuminous liquid, which, hardening after the eggs are laid, forms a second external envelope.

This error of attributing the viscous secretion to the oviducts has been repeated
by subsequent writers, notwithstanding the fact that it was corrected by Milne’
Edwards (60) in a subsequent work. He says in a note following a recapitulation of
the observations of Lereboullet, that the glue by which the eggs are attached does not
come from the walls of the oviduct, but is secreted by subcutaneous glands situated on
the under side of the abdomen, between the bases of the appendages. A membranous
penis is said to be formed by the subdermal portion of the seminal tube, which is here
enlarged and has thickened walls. This dilated portion of the canal, the “vecteur” of
the sperm, “is capable of evaginating and passing outside beyond the genital opening,
to the borders of which it is inserted. It thus forms a tubular appendix, having the
function of a penis.”

Milne Edwards was undoubtedly mistaken in supposing that the large glandular
segment of the vas deferens of the Macrura was evaginated in copulation. This, as
Grobben remarked, would be mechanically impossible (83).

Duvernoy (57) in 1850 again raised the question whether fertilization in Decapod
Crustacea took place at the moment the eggs were laid, and comes to the conclusion
that in Macrura and some Brachyura, where there is no seminal reservoir, fecundation
takes place without a true copulation. He says:

The way in which the oviducts are stuffed like sausages with large numbers of eggs arranged in
line, when they have reached maturity, would not admit of an internal fertilization, except for those
eges which were brought near the orifice, unless there was a copulatory pouch or a seminal reservoir;
before the mouth of which they mustsuccessively pass at the time of egg-extrusion, in order to be
fertilized, as is the case with insects.

He supposed that in all cases where internal fecundation was impossible, the eggs
were fertilized at the moment they were laid, as ovcurs in the tailless Batrachians; he

THE AMERICAN LOBSTER. 39

had also the notion that the male helped the female to place her eggs under the
abdomen and glue them to the swimmerets.

Apart from the physical impossibility of an internal copulation and fertilization,
in the way which many have conjectured, the absence in the Macrura of two important
accessory reproductive organs, the vagina and internal seminal receptacle, points at
once to the fact that the eggs are fertilized outside of the body. With the discovery
of an external seminal pouch in the lobster, the function of which had been curiously
overlooked or misunderstood until Bumpus called attention to it in 1891 (30), this is
still further emphasized.

As Brocchi and, more recently, Cano (32) have pointed out, the vagina and inter-
nal seminal receptacle always occur in the Brachyura in relation to the presence of a
male penis (the terminal portion of the efferent duct which is said to be capable of
evagination), and imply a different method of copulation.

The common green crab (Carcinus menas), the pairing of which has been repeat
edly observed, illustrates this process among the Brachyura. <A pair of these crabs
was brought into the laboratory at the United States Fish Commission at Woods
Hole on the 27th of July. They were adherent solely by the intromittent organs!
of the male, which were introduced into the orifices of the oviducts of the female.
The male had a hard shell; the female, which was smaller, a soft shell, conditions
which seem to be necessary for copulation, as Cavolini (36) loug ago showed, and as
Bouchard-Chantraux (27) and Lafresnaye (117) independently observed (25).

Cano gives the following account of the copulation of Maia (33):

The male crab runs to meet the female, lifts her up and places her beneath him, embraces her
closely with his feet, and his claws hold her by the margin of the orbits or in the region of the
antennxe. In other cases the male turns upon its back, catches hold of the female and draws her
upon his belly. The whole action lasts about an hour.

It is undoubtedly true, as Cano has remarked, that in all the Macrura and Ano-
mura, which have no internal receptaculum seminis, penis or vagina, there is no internal
copulation and the sperm is never found in the ovary or its ducts.

THE LAYING OF EGGS.

In order to determine the time and limits of the breeding season of the lobster, it
is necessary to collect and examine a large number of their eggs at different places
and at different times of the year. The examination of the winter or summer eggs
alone will not suffice to solve the problem, as I have learned by my own experience, and
this explains why the question has been the subject of so many conflicting statements
and has remained unsettled down to the present day. (For a review of this question
see Nos. 98 and 101 of Bibliography.)

The following quotations illustrate the confusion which has surrounded this
important subject. Verrill (196) remarks:

There is a great difference in the breeding season on different parts of the coast. The lobsters
from New London and Stonington often lay their eggs as early as the last of April or first of May;

while at Halifax Mr. Smith found females with recently laid eggs in September. At Eastport, Maine,
the females carry their eggs in midsummer.

'The only intromittent organs noticed in this case were the slender wand-like appendages of the
first abdominal somite. The penis is probably introduced after the former have been withdrawn.
(Compare p. 37.)

AQ) BULLETIN OF THE UNITED STATES FISH COMMISSION.

At the time this was written it was not known that the lobster usually carries
her eggs for a period of ten or eleven months. It was, therefore, quite natural that
Verrill should misconstrue the discriminative statement of Smith (182), who says:

The season at which the female lobsters carry eggs varies very much on different parts of the
coast. Lobsters from New London and Stonington, Connecticut, are with eggs in April and May,
while at Halitax, Nova Scotia, I found them with eggs, in which the embryos were just beginning to
develop, early in September. A corresponding variation is noticed in the lobster of the European coast.

Verrill further says (196, p. 745):

Subsequent observations have shown that the breeding season of the lobster extends over a large
part of the year. * * * Mr. Vinal N. Edwards has forwarded two living females, of medium size,
taken in Vineyard Sound, December 12, both carrying an abundance of freshly laid eggs. He states
that he finds about one in twenty carrying eggs at that season.

Wheildon says, in a paper published in 1875 (202), that the assumption that the
lobster has a definite annual spawning season is an error, and that in February of that
year he had obtained ‘spawn in several stages of development from newly laid eggs
to the swimming larvie.”

The following statement of a member of the local government of Prince Edward
Island expresses an opinion upon the breeding habits of the lobster, which is as
misleading as it is common:

I feel certain that the close season has not and can not accomplish anything toward the first
object [protection for lobsters while spawning], as it is now admitted by everyone who has had any
experience in packing, that lobsters in spawn are caught at all seasons of the year and that they
have no particular season for spawning.

Bumpus concludes that—

The eggs are normally deposited during the months of July and August, and develop rapidly so
long as the water is relatively warm. * * * Large numbers of eggs collected during the winter
months, both from the colder waters of Nahant as well as from the warmer waters of Woods Hole,
were almost invariably in the same advanced stage of development—the eyes large and bright, the
appendages well outlined, and the yolk occupying but a fraction, perhaps one-third of the surface
exposure.

Out of hundreds of lobsters found “in berry” in May, 1890, at Woods Hole, “ not
a single one had eggs in early stages of development.” (30)

After fluctuating from one view to another, I came to the conclusion that the
breeding season was limited as defined in the paragraph just quoted, but as my obser-
vations had been restricted to the summer months and to the region about Woods
Hole, I determined to extend them to other points of the coast and to other seasons
of the year. The results of these inquiries I will now give in detail. They may be
summarized as follows:

For the majority of lobsters there is a definite breeding season, which is the
summer, July and August being the months in which the greatest number of eggs are
laid. A minority, on the other hand, perhaps 20 to 25 per cent of the entire number
of spawuers, lay their eggs at other times of the year, in the fall and winter at least,
if not also in the spring. The fall and winter eggs are normally extruded, and do not
appear to be necessarily the product of the first reproductive period. A glance at
table 12 shows that while the average size of the females is small, it is fully up to the
average of all females captured during the same time.

I received an “egg-lobster,” which is not recorded in the following tables, from
Woods Hole early in December. It was 123 inches long, and its eggs were just past
the egg-nauplius stage. If laid in July or August, they would have reached this stage
in about 18 days.

THE AMERICAN LOBSTER. 41

SUMMER EGGS IN VINEYARD SOUND.

The following tables illustrate the time of spawning of the lobster in the vicinity
of Woods Hole, in Vineyard Sound, and about Gay Head. The date of the extrusion
of the eggs is, of course, only approximately determinable. It is estimated from obser-
vations on the rate of development of embryos at Woods Hole. The parent lobsters
were confined in floating latticed boxes, which were exposed to the wash of the waves,
in one instance, for nearly a year. (See table 18, p. 56.)

TABLE 3.—Time of spawning of the lobster in Vineyard Sound and vicinity in 1889.

Date of : . Dateror
No. Locality. ras - Stage of development. Age of embryo. | extrusion |
. capture. F of eggs. |
| |
1 Woods Hole Harbor..| July 10 Thoracic abdominal plate well marked ...) 8 to 9 days.-.--. July 1 |
2 | Menemsha.....-.....- July 11 At least four pairs of appendages behind | 20 to 21 days.-..| June 20 |
mandibles. |
..-do..-., Egg nauplius: second antenne bilobed... 14 to 15 days.--., June 26
eee Omer | seme (i) panéacoscocdaomsaeccens sockene saba65| Heap dopa eetees. Do.
9 US cecdlooon CWmaocodedonsennpenandepbansauescbsad Ihieuee Ov tessiclselel='s Do.
..-d0....| Close of yolk segmentation........-.-.... Bidayeitecccsa se July 8
ech osod Yolk segmentation: 60 to 100 segments...) 14 days .-.----.. July 9
os A = See bbodoct SocoeatosccasceshoqusconsaaEegponeecslbeoane doeeseeeea Do.
Sod Aaea . Noes bedos sdeabonoae | Do.
S6chi OF Sded Gnoaet lO) ecuecsaccbeeded Aadces Sere cee eee oan Bere (UW easosossas Do. |
neti! eal hooded (hres Sencne ah Onenonceeariet CocEcce meee eee dorenen eee Do. H
.-do....| Early egg nauplius: second antenne not | 10 days .------.. July 1 |
bilobed. |
UGS eee oe GW sscoscseeeanosos July 16 | Egg nauplius, later stage: second anten- | 14 to 1l5days....| Do.
nw bilobed.
5 S06 | Close of yolk segmentation...-.-------.-. BGEW A adocogacas July 13 |
--do ..-.| Thoracic abdominal plate becoming prom- 6 days......-..-- | July 10 |
inent.
. do. Yolk segmentation: 50 to 100 segments. - 4 IGG ER GS Goosadone July 14 |
fal eee GW zscécdocheasocne July 18 Large prorat abdominal plate. Pit ob- | Sto 9 days...... July 9 |
scure

1K} | pan ae GD coseoudacocseces July 20 | Very slight invagination: nuclei close to | 4 days .--...---- | July 16 |

surface. |

iG) | beaae GW schoccsécccsoees July 28 | Eye pigment developed........--.-------. WatidayStacaeee | July 1

20) /=2-= (GW) acoaconsneecaose NWS 18} |b oece Oj eee Bee teen cite eee cee eacecee | oo. a Wasesseesce July 7

i _ — —— —— — ——
TaBLE 4.—Time of spawning of the lobster in Vineyard Sound and vicinity in 1890.
. , Date of
No. Locality. Ee oF Stage of development Age of embryo. | extrusion
pture. S
| of eggs. |
| Yolk segmentation probably not begun...| 24 hours ....---- July 6
Yolk unsegmented Seer ee eee ee | Few hours...---| July 9
Post- nauphius BIRTH eo ceopsecnuasnopbacosbod 21 days ...... July 7
---| Eye pigment just Web Gon ceccesedscosas TOBY Sree eer eine | July 1
oy Soe .---| Close of yolk segmentation.........-.---- 3 days ee teeets July 25
TY hoses COM one ---do ....] Invagination stage, small pit........----. 4 to5days...-.- | | July 24
18h | seaee CW bedesStosopapecc =O a5: Yolk : segmentation : 16 to 60 segments. -..- 24 to 30 hours...| July 27
1 eee GO) ssoandaessceesos “July "30 | Yolk unsegmented BOGORURE SCS ESBS OARS A few hours ....| July 30
20neeeae (i) Soa coaneoosesoDE July 30, |..--- GW) Socrcodacocacensseoncsacousegecasées About 8 hours..| Do.
1.45 p.m. |
21-26 |.---- GN) cecctooeHesosooe July 30 | Early segmentation of yolk............--. 24 to 30 hours...) July 2
PRED [locos GW) coscdecSenccados ..-do ....| Close of yolk segmentation y
46-51 |.-... GW caeteeptoeccesac ..-do ....) Invagination stage peooEaccooCUpouseebscedc J
52, 53 | do do ....| Egg nauplius Dr ee toto st stetctoetetete tae nee eee 5 day July
-| Eye pigment formed....... -.-------..--- PUGEN EY oxeacee se | July
Egg nauplius SEE Sn Ano nor ones cnced se WL DID RY S ewe ce eras - | July j
--- Close of yolk segmentation. ...-.-...-.... SIGE Ey 563 agecemts | July 29 |
Seidl) SEGyIs segmentation: 16 to 60 segments --.-| 24 to 30 hours.-.| July
‘| Thoracic abdominal plate formed.... ..-. 8 to 9 days...... | duly §
S) | Pinvecin ations eee ee eee mene |poidaysys--eesee. July ¢
IDEM Vou ho sesso bane paconcnc os aomoesS 15 days eee July 2
=: | Hyeypigment formed)... oeae eee = | 27days :.--2...-| July 15. |
iiinvarinationses.o-scosesee cesses GEV sesoscasse Aug.
---| Thoracic abdominal plate formed. . 3 ‘| 8to9 days...-.- Aug.
al eos inaupliuss. os. cos se se oe ee nena aes lel 5idaysies amass July 27 |
Helin a ein ation -m eae = melee ee ls GEMS nesesoeeoe Aug. {

5 --| Post-nauplius stage-----------...-----.--. | 20 days -.--..--- July :
LOMK | eee do | A mya pin ation (\8) eee = eae eee tee BCEN A ssuscaener Aug. 13?
78-81 Menemsha ae. Egg nauplius BB ecng eesoosaéoocooscseases (oidayseeeseece. Aug £
82-84 |..... do ..| Post- nauplins| stay G-- sess sees esse eee eczladtyS\seoe ees - July :
RESET Te eae! do | Early egg nauplius Ree eer mor Sek seers |) L0idays <-=--2--: Aug. 11

42 BULLETIN OF THE UNITED STATES FISH COMMISSION.

TABLE 5.—Time of spawning of the lobster in Vineyard Sound and vicinity in 1891.

| Date of

PezNio; Locality. | Date or Stage of development. Age of embryo. | extrusion
| capture. | 5 3 U
| | | of eggs.
I GayiHeads. cs. =2e- sce July 19) Yolk sepmentations-----22 +92 fees
PN ees (SRE or aeneoenmes July 23 | Close of yolk segmentation-........--..-.
3 | Menemsha..-.......-. uly 285 |elnvaoinatlonyescsesceca- sees eee cece er
| Vie Sesece (ibe Geareacseaees |..-do....| Late stage with eye pigment.......---.--.-
Di eeee CRA en omcreer sel Incd do ....| Close of yolk segmentation...---...-..--.
GyliGavsbliesdi iss emcee se July 29 |....- Op eee e Soe ee eee
hel esse (rasdonanonkernolese do....| Eye pigment formed..-.-..--..------ anos
Sileeces UW) SAdaHsesSoaacBRG A 6x doe eel nesinauplinssteese see sma eee emer
9,10 | Menemsha...-......-- Aug. 5 Tuvagination (CD) aren en oe
i =13 5 ee igsSresaseanenses je SdOn alee) COs. ccheerct asters eater teases
14-16}. 2... (iy peeosaanousanpoe |- peaClOpsece Clone ¢ of yolk segmentation. ......-...--..
17-21 |....- Gi astbasedosence. eed OR c|Pnoo mauplius er serra crete tere eae
22M eae (byirerarcanpmacccasligas do ....| Late stage, eye pigment conspicuous. -----
23 | Woods Hole Harbor...) Aug. 8 | Before formation of eye pigment......-...
of eGayadleadecn-- == one | Aue 119 inva sc inationeess eee eee ee ener
25,263) (2-02 dome tans eae |_..do....| Thoracic abdominal plate me sees cneeen ene
PY PN Ges cicre UW sccacdaseutsecsalloss dol ese eonaupliseesseereeme casero esses sas
283i eee (Gh eascescasosueseal ese do .---| nes Rneup uns Sta geese eee ener
29,30 | Menemsha....-.....--. | Aes 12 | Early egg nauplius---...-..--
| 31 Woods Hole Harbor... Aug. 12 Invagination eee eee
2 | r Egg nauplins, late stage. - -
| ges tree inripe ovary ------.------.-----
Egg nauplius, latestage.--.----.. - -- ---
we Eye pigment forms large, nearly oval spot
| -| Egg nauplius mbaoteséauacoocodacecshcesca5¢ Tb dayssseenseene
| |

TABLE 6.—Time of spawning of the lobster in Vineyard Sound in 1892 and 1893.

Date of Date of c
No. Locality. en fn Stage of development. Age of embryo. | extrusion
s pture. 0 Otlee
| Es.
|
1892
| 1 | Woods Hole Harbor --| July 29 | Invagination .......---...---.---.-------- LICE soebessase July 25
| PY Nees aed Uocseene es tee Jilys30N Phe emanplivsseeee esa e- eee ee eee eer IIDGENG Gaeeeccas July 15
By lata (Uy Ses asesndnooacee Aug. 1 Be, ginning of yolk segmentation.---.-.--. GERMS seososo5' July 31
Le oeoow Gi) Wee ees an eneasete goed0e-.:|elnvagination eee seer rete e eee eeeee
SU eee dO eee e eee eee Aug 3 | Close of yolk segmentation \
Gi lldeere OM caastbiador U2A|) do--22| Post-naupliusistagess ss ene ae 0 days July 14
Te \aaes osetia .--Qo ....| Before eye pigment isformedspeeeeee eee PAGER) se 8eqsege July 8
Sblemeen do Aug. 6 | Yolkunsegmented aBacachaas snesousetadaoc About 1 day -...) Aug. 5
1893.
1-3 | Menemsha.........--. July 25 x ew eggs: stage not determined ----.-...|--.-..--..---..---|-.---- ese
4 | Woods Hole Harbor ..| Aug. 11 | Eggs laid in aquarium ataUmitedastates’|peateeseeeaeaeaean About
Fish Commission station. | Aug. 10
5 ----| Aug. 15 | Close of yolk segmentation..-.........-.- Aug. 12
Gil eaeredOwaccese cee seboenleee do ....| Five pairs of appendages behind mandi- July 23
bles; no eye pigment.

TABLE 7.—Variation in time of spawning of lobsters in Vineyard Sound and vicinity in the years 1889-93.

|
Period of spawning. 1889. | 1890. | 1891. | 1892. | 1893. | Total.

16-31

The data afforded by the preceding tables lead us to conclude that the summer
eggs are produced in this region during a period of about nine weeks, extending from
the middle of June to the middle or last of August, the largest number being laid

THE AMERICAN LOBSTER. 43

during the latter half of July and the first two weeks of August. The summer
spawning of each year lasts about six weeks, but may fluctuate from year to year,
backward or forward through an interval of a fortnight.

The observations for the years 1890 and 1891 only, are large enough to make a
comparison of much value. Of the 86 lobsters with new eggs examined in July and
August, 1890, 85 per cent extruded eggs in July and 15 per cent in August, while in
the following year, out of 38 females, one-half had laid in July and half in August.
In 1890, however, 72 per cent of the eggs were laid in the latter half of July and 15
per cent in the first half of August, while in 1891 47 per cent were extruded in the
first part of August and 351 per cent in the latter half of July. The season of 1891
thus appears to have been somewhat later than that of the former year.

The record of ocean temperatures given in table 2 (p. 25) shows that the water
was cooler in 1891 than in the preceding year, the difference of the mean annual
temperatures being 1.69. This difference is slightly raised by eliminating the month
of June, when the smallest number of lobsters carry eggs. It is possible that so small
a variation as is here recorded in the mean annual temperature of the sea water would
sensibly affect the rate of development, yet a larger number of observations would be
required before this could be satisfactorily shown.

There are undoubtedly other causes than the temperature changes which influence
the growth of the ovarian eggs, which it must be remembered require at least two
years to reach maturity. Anything which affects the individual during this interval
may affect also the time of spawning, and this affords a partial explanation of the fact
that eggs are sometimes produced at other seasons of the year than the summer.

SUMMER EGGS ON THE COAST OF MAINE.

Tables 8, 9, and 10 throw more light on the time of spawning upon the coast of
Maine, where the water is somewhat cooler than at Woods Hole. The range of tem-
perature in the Gulf of Maine is about the same as that obtained at Pollock Rip
light-ship, off the southern end of Cape Cod, namely, 32° to 62° F.

TABLE 8.—Time of spawning at Southport, Maine.

[Many of the lobsters were captured in Nova Scotia and brought to Southport before laying their eggs. ]

| |
|

Me Sl cette Age | Dato of

No. | Place of spawning. eaten of Stage of development. of em- | extrusion

| | racers | bryo. | of eggs.
| So

. 7 | Telson in front of optic lobes: Eye-spots oval.--..-. 61 July 8

..-| Eye-spots lenticular or nearly semicircular. ......-. 35 Aug. 3
.--| Eye-spot narrower than in Nos. 2-3 .-.-...--.--.... 33 Aug. 5
.| Eye-spot, small crescent .........-.-..-.---.. 30 Aug. 8

écllogacd (1) aceceosncadadosc 29 Aug. 9

---| Bye-spot, linear. .....-.- 27 Aug. 11

-| Before formation of eye } 25 Aug. 13

:| Egg nauplius, late stage.-....-.-----.--2.--- -| 18 | Aug. 20

44 BULLETIN OF THE UNITED STATES FISH COMMISSION.

TABLE 9.—Time of spawning of the lobster at different points on the coast of Maine. !

| > |

| | Date or Age | Date of

No. Locality. eee Stage of development. of em- | extrusion
: nation of NE Oheres
| eggs yo. ges.

| 1893 ; | Days |

1-2) Vinal Havens2:.--42:- Aug.+26) | Hye-spot; smalls crescen Giessen nical 29 | July 28 |

Bilsaeoe dO) Sah: cheer Aug. 28 | Late segmentation of yolk.-....:--...---..-4..----- 3 | Aug. 25 |

4-7 |.-..- (re kee des sas ceaae: IRIE BN) | ba aesuSossoncsodanbdodsesa5005 [sosdaodooek Ousedosueaae 33 | July 30 |
8 | North Haven ..--..--. Aug. 28 | Eye-spot asmallcrescent...---...-----.-.:.2-------- 29 | July 31
9 | Vinal Haven..-.:..--- Aug. 26 |..-.. 1) necgosssouoboudesandon) ndpecansssndbocssasasas 29 | July 29
LO) eee Gli} eacisadass onsets Aug. 31 GW SSbodsesad spocad suc sauDeagEscu secdcdanaussaee 29 | Aug. 2
iil, Wades Gh) gon6penecc8sa553 [eer Oversee cteraces GU Wacaséocnadanpsonscacombeeaskeodedcosessancusas 28 | Aug. 3
12-13 S Gli) scobecqqeecspsee Gh) Sealleeace (ho) Seasons sicosbao ca asoensomeEnasoaaarassesucses 29 | Aug. 2
14-17 ..-.- Opto soee sect eit Sept. 2 |.--.- (} Boiso5- sooncedreecuosaeesbahensusdcooonosaouscs 29 | Aug. 4
IG) eece Wee See beeaanueaps Ang21262!5Rost-nauplinsiStagey ee seen = ccs teers serie eer 21 | Aug. 5
19-20 |....- (Wintspacusaosasas (MATIO. aGslrye-SpObiime are stateyetatelele te tat = oer elope tele telerietedorerr iat 27 | July 10
Pal Redse Gl) socoustaeaodaese Aug. 31 | Post-nauplius stage-.------------ 2-25-2222 -2 62 -=--- 21 | Aug. 10
A eee OEE reer eee tieee lsSeptymla peace (Eke pace panbsosbeoadoestvernacestastoesanonadce 21 | Aug. 11

23 | Millbridge--.--..-..--. ANS 926) |e Gyn AULD US peepee reat eee ee eel tetstet 15 Do.

24 | Vinal Haven.......-.. tsi) Sums 2 | oes (Gy peceebaccscncccenpapcononsoo saoassebdsuosenae 15 | Aug. 18

25-26 |....- (yond cetosbeodse Aug. 31 | Segmentation of the yolk................-.--------- 14 | Aug. 29 |

The results given in tables 8 and 9 are combined in table 10, which may be
compared with table 7. In the first column, taken from table 8 (in which some of
the lobsters were brought from Nova Scotia to Southport, Maine), all but three
individuals extruded eggs during the first half of August. In the second column
46 per cent laid eggs during the same period. Combining the results of the obser-
vations at Woods Hole for five years, 1889-1893 (table 7), we find that 52 per cent of
egg-bearing lobsters, in all cases observed, laid in the latter half of July, while about
21 per cent spawned during the first half of July and an equal number in the first half
of August. We find that 66 per cent of the individuals recorded in table 10 laid eggs
during the first half of August. These results tend to show that the summer spawning
season in the middle and eastern districts of Maine is about two weeks later than in
Vineyard Sound.

TABLE 10.—Time of spawning of the lobster on the coast of Maine for the summer of 7893.

| Data from | Data from

|

Spawning period. error lerae | table 9, | Lotals. |

| |

|

July, 1215 200 1 | 2 Siac

July 16-31 ..- 0 | 8 8 |
August 1-15 .. 22 | 12 34

August 16-31 -..-...- 2 | 4 Gia

| ———.

Number examined......--..- 25 | 26 51 |

FALL AND WINTER EGGS AT WOODS HOLE,

The catch of egg-bearing lobsters in the harbor of Woods Hole for seven consecu-
tive months is given in table 11. Out of a total of 168 captured, 21 per cent were
taken in January, 6 per cent in February, and 20 per cent in April. Of the entire
number, 25.5 per cent bore eggs which had been laid during the fall and winter months.
This fact was determined in the following way. Some of the eggs of every lobster
captured were preserved and carefully examined. Where no eye pigment was present
it was at once evident that the eggs had been laid at a comparatively recent date. In
all other cases the pigmented areas of the eyes were drawn to scale and compared with

‘For the collection of eggs at various points on the coast and islands north of Massachusetts I
am particularly indebted to Messrs. F. W. Collins of Rockland, M. B. Spinney of Cliffstone, J. W. Fisher
of Eastport, and also to Mr. Greenleaf of Vinal Haven, Maine.

i ini

q
'

THE AMERICAN LOBSTER. 45

a series of similar drawings of embryos developing under normal conditions from
summer eggs.

The eye pigment furnishes the most convenient scale for the measurement of the
rate of development of the embryo as a whole, since it appears early, is clearly defined,
and since the development of the eye is correlated with that of the other organs of the
body. Where the ocular pigment forms a thin crescent in eggs taken in January,
the embryo will be found in a stage of development similar to that reached in the
summer eggs four weeks after fertilization. In such a case, it is a safe inference that
the ova have been laid in the fall. Again, when in May or early June the area of
ocular pigment is not greater or is less than that observed in summer eges by the first
of September (cut 36, pl. J), we may be confident that such eggs were extruded later
than the previous summer.

TABLE 11.—Number of egg-lobsters taken at Woods Hole. (See table 21.)

Females Females
Females | with eggs | witheggs p,.
Time. with eggs. laid in. | laid out of Choon 2
(dD) July and season. be ‘
August. “ (a)
1893.
December -.....-.-- 22 17 5 22.7
1894.
VER WENA7 asoaoadecee 36 24 12 334
February -------.-- 11 9 2 18
Marcheseese= eee 12 9 3 25
A\j Ne Sm opepadaoacd 33 26 7 21
Maly ete nen none 34 26 8 23.5
dhe pasesoscesens 20 13 7 35
Motaleeease eee 168 124 44 25.5
|

Table 12 shows the stage of development of the eggs of 44 lobsters taken under
the conditions described (p. 25) and compared with the normal condition of summer
eggs shown in table 18, lobster No. 3 (1) to (20). These comparisons are rendered
clearer by a series of drawings (cuts 25-38) made from the eggs of this lobster.

TABLE 12.—Stage of development of eggs laid in fall and winter at Woods Hole.

| Length

Leugth|
No. Date. ing] Stage of development. || No. Date. | in Stage of development.
inches. | | | inches.
es 2: | Ree AD zat
1893. | 1894,
1 | Dec. 20 104. No eye pigment. Like stage 3 22 | Mar. 15 94 | Like 3 (11), table 18.
| (7), table 18. 23 | Apr. 16 10 | Little earlier than 3 (10), table 18.
2 | Dec. 23 94 | Forked telson overlaps brain. 24 | Apr. 17 10 Like 3 (9), table 18. |
| _ Like preceding. 25 | Apr. 17 10 | Little earlier than 3 (10), table 18. |
3 | Dec. 25 8 Like 3 (11), table 18. | 26] Apr. 18 ll Little earlier than 3 (9), table 18. |
4 | Dec. 26 10} | Like 3 (7), table 18. | 27] Apr. 19 84 | Like 3 (9), table 18. |
5 | Dec. 27 8 Trifle later than 3 (9), table 18. || 28) Apr. 20 104 ; Like 3 (10), table 18. |
1894. 29 | Apr. 21 9 | Little earlier than 3 (9), table 18.
6/ Jan. 1 114 | Like 3 (9), table 18. 30 | May 1 10} | Little earlier than 3 (10), table 18.
7| Jan. 2 91 | Like 3 (10), table 18. 31| May 1 74 | Like 3 (10), table 18. |
8| Jar. 3 114 | Like 3 (9), table 18. 32 | May 3 103 | Little earlier than 3 (9), table 1s. |
9| Jan. 3 94 | Like 3 (11), table 18. || 33) May 8 94 | Like 3 (9), table 18. |
10 | Jan. 4 9 | Eye pigment just visible. 34| May 9 10 | Like 3 (9), table 18.
11 | Jan. 9 10 | Like 3 (6), table 18. 35 | May 10 10 | Little later than 3 (9), table 18.
|} 12] Jan. 11 104 | Like 3 (10), table 18. | 36) May 11 7 Little later than 3 (9), table 18.
| 13} Jan. 12 10 | Like 3 (10), table 18. | 37) May 12 9 | Little earlier than 3 (9), table 18.
14 | Jan. 13 10 | Like 3 (9), table 18. 38 | June 7 9 | Like 3 (11), table 18.
15 Jan. 20 9 | Like 3 (10), table 18. || 39| June 7 11 | Like 3 (11), table 18.
16 | Jan. 27 10 | Like 3 (10), table 18. || 40) June 9 83 | Like 3 (11), table 18.
17 Jan. 31 10 | Like 3 (9), table 18. 41 June 8 11 Little earlier than (11), table 18.
18 | Feb. 19 91 | Like 8 (11), table 18. } 42 June 11 10} | Like 3 (11), table 18.
19 | Feb. 5 | 9 Like 3 (9), table 18. 43 June 12 10 Like 3 (11), table 18.
20 | Mar. 10 | 104 | Like 3 (11), table 18. | 44 June 14 93 | Like 3 (11), table 18.
21 | Mar. 13 | 104 | Like 3 (11), table 18. |

46 BULLETIN OF THE UNITED STATES FISH COMMISSION.

FALL AND WINTER EGGS IN OTHER PLACES.

The conclusion that the production of eggs in the fall and winter is of general
occurrence throughout the entire range of the lobster is supported by the observations
recorded in table 15, Here are eggs, none of them laid during the summer months,
coming from a wide area from the middle and eastern parts of the Maine coast, from
the outward islands, and from the province of New Brunswick. They are compared,
as before, with the rate of development of summer eggs observed at Woods Hole
[lobster No. 3 (1) to (20), table 18]. In one instance, No. 20, the yolk is unsegmented,
though taken in February; in others the egg nauplius, which in summer appears at
about the fourteenth day, is barely outlined.

TABLE 13.—Stage of development of eggs laid in fall and winter on the coasts of Maine and Province of
New Brunswick.

v ity | Stage of °f 2 eee Stage of
No. Date. | Locality. development. No. Date. Locality. development. |
| 1893 | 1894.
1 | Nov. 10 | Isle au Haute..--.---- | Like 3 (9). | 21]|) Feb. 5 | Matinicus Island -....- Like 3 (10).
2 | Nov. 15 | York Island .--.--..--- Late segmen- 22 | Feb. 8 | Ragged Island....... Like 8 (8).
| | tation of 23 | Feb. 10} Usleau Haute..--..... Like 8 (10).
| yolk (?). 24 |\Feb. 10 | Isle au Haute..---.--- Like 3 (9).
3 | Noy. 25 | Cranberry Isle. -.-..--- | Egg nauplius. 25 | Feb. 14 | Long Island ......---. Like 3 (4).
| Earlier than 26 | Feb. 17 | Matinicus Island ..--.| Like 3 (10).
4 (8). | 27 | Feb. 21 | Mount Desert.-...--.. Like 3 (8).
4 | Dec. 11 | Matinicus Island ..--- Like 3 (9). || 28] Feb. 22 | Cranberry Isle..-..-.-. Like 3 (9).
1894 | 29) Mar. 1 | Cranberry Isle-.-..-..-- Like 3 (10).
5 Jan. 11 | Beaver Harbor, Bay | Like3 (10). || 30) Mar. 1) North Haven .--..---.-. Like 3 (5).
of Fundy. 31 | Mar. 10 | Isle au Haute..-...--. Like 3 (10).
6 | Jan. 13 | Mount Desert -.-...-.- Like 3 (9). 32 | Mar. 13 ! Matinicus Island ----. Like 8 (9).
7 | Jan. 15 | Cranberry Isle.-...-.-.-. Like 8 (10). Boll Marwmloe |e vorkulslandiaeeee=eres Like 3 (9).
8 | Jan. 17 | Isle aa Haute. .--..-.. Like 3 (9). 34 | Mar. 20 | Cranberry Isle--.--.--- Like 8 (9).
9 | Jan. 18 | Eastport--------.---.- Like 8 (10). 35 | Mar. 22 | Ragged Island..-....-- Like 3 (9).
10 | Jan. 18 | Musquash Bay, 35m. | Like 3 (9). 36 | Mar. 27 | Fox Island.........-.- Like 3 (9).
east of Eastport. 37 | Mar. 29 | Matinicus Island ...-. Like 3 (9).
11 | Jan. 19 | Seeley Basin, 24 m. | Like 3 (10). 38 | Mar. 30 | Brimstone Island -.--. Like 3 (11). |
from Hastport. | 39 | Apr. 1 | Swan Island ........-. Like 3 (9). |
12; Jan. 20 | Baker Island. Like 3 (10). ||) 54.08) 2Aspr9815i|Moxelslandeeeeer neers Like 3 (10).
13 | Jan. 20 | Otter Creek- - -| Like 3 (9). 41 | Apr. 10 | Eastport.--.. -| Like 3 (10).
14 | Jan. 21 | Eastport--.---.-...--- Eye pigment 42 | Apr. 15 | Baker Island-. .| Like 3 (10).
| just visible. | 43 | Apr. 24:| Hastport.....---.-.--. Like 3 (10). |
15 | Jan. 22 | 10 miles from St. | Like 8 (10). | 44 | Apr. 26 | Deer Island, 4 miles | Like 3 (11). |
, John, N.B. | from Eastport. |
16 | Jan. 24/18 miles from St. | Like 3 (10). 45 | Avpr: 30) || Bastport.=.2-2------ | Like 3 (11).
| John, N. B. | | 46 | Apr. 30 | Islesboro -.------.---- Like 3 (11).
17 | Jan. 27 | Brimstone Isle.-.------ | Like3(4). Late | 47 | May 1) Green Island..-.-.----. Like 3 (11).
eggnauplius.|| 48 | June 10 | Matinicus Island..--- Like 3 (9). |
18h kane 20 |eisleausklantes eee Like 3 (6). 49 | June 8 | York Island ----2:.--- Like 8 (9).
19 | Jan. 17 | Spoon Island ...-.---. Like 3 (9). 50 | June 13 | Vinal Haven. ..-.----- Like 3 (10). |
20 | Feb. 4 | Matinicus Island ....| Yolk unseg- | 51] June 20 | High Island.-.-.-.--- Like 3 (11). |
| | | mented. } |
| |

Mr. N. F. Trefethen, of Portland, who deals extensively in lobsters, and who has
a lobster pound in South Bristol, 35 miles east of Portland, believes that some lobsters
in that vicinity spawn in June. In support of this view he cited the following case:
In the latter part of May, 18938, he placed 20,000 lobsters in his pound and took them
all out at intervals in the month of July, beginning the first of the month. All the
lobsters had been examined before they were placed: in the pound, and none of them
were known to be with spawn. At the most only a relatively few egg-lobsters could
have been put into the pound by accident. When taken out about one-third of the lob-
sters had spawn attached to the body. It is thus evident that some of these females
must have laid their eggs in June or in the first part of July. No tally was kept of
the proportion of egg-lobsters taken out during the first part, the middle, and the
latter part of July, and it is possible that the great number of egg-lobsters, which

{

THE AMERICAN LOBSTER. 47

caused surprise, may have laid their eggs during the last half of July, and that very
few in reality extruded their eggs during the first part of this month. It is not
probable that any eggs were laid in June.

In the second week of August, 1593, a vessel came into Portland, Maine, bringing
lobsters from Seguin Island and Georgetown. Very few lobsters were at this time
(August 13 to 20) with spawn.

[have been told by fishermen and others that lobsters are sometimes taken out
of the wells of smacks in winter with very dark, external eggs, when it had been the
rule to carefully exclude every egg-lobster in loading the boat, the inference being
that lobsters had laid while in the well. Allowing a wide loophole for error in such
cases, it is very evident from the facts already recorded that this is quite likely to
happen.

Mr. Nielsen gives the spawning period for lobsters in Newfoundland as extending
from the 20th of July to the 20th of August (Annual Report of the Newfoundland
Fisheries Commission, 1892), but also states, in reply to certain questions which I
endeavored to have answered, that lobsters were taken with newly laid eggs up to
the latter part of September.

The spawning months for the lobster in Prince Edward Island are said to be July
and August. We have no data whatever upon the spawning habits of the lobster on
the coast of Labrador, or in the extreme southern parts of its range.

Considering the fact that the lobster is distributed through 20 degrees of latitude.
there is less variation in the time of spawning than might be expected.

THE LAYING OF THE EGGS AND THE ABSORPTION OF OVARIAN OVA.

I have not seen the process of egg extrusion and consequently have no direct
observations to record. It has, however, been witnessed in other crustacea where it is
undoubtedly similar. In two instances lobsters have laid eggs while kept in small
aquaria in the laboratory of the United States Fish Commission. Since these animals
were under constant surveillance during the day, it is almost certain that the eggs
were deposited in the night or early morning, as is the well-known habit of many
decapods. In each case the mother lobster scratched off nearly all of her eggs in the
course of afew days.' In other attempts to observe this process, where the eggs seemed
to be overdue, I dissected the animals and found that the ova were retained and partially’
absorbed. This led to other attempts with similar results.

Two “ripe” female lobsters, measuring 11.5 and 9 inches, respectively, were cap-
tured July 30 in Woods Hole Harbor, and placed in a large floating car, which was
kept covered so that the lobsters were not exposed to direct sunlight. Fifteen days
later, August 14, their ovaries were examined. In the smaller individual more than
half the ovarian eggs, which were overdue, were in various stages of degeneration,
thus giving the ovary a remarkable appearance. Instead of the uniform dark. green
hue, it was of a light yellow or straw color flecked with darker green areas, where

1 Bhrenbaum (62, p. 287), who mentions a single case of a female lobster which was found lying on
its back shortly after the eggs had been extruded from the body, says: ‘‘The mass of eggs lay in the
mold formed by the folded abdomen without being fixed, since the cement had not as yet hardened.
When the animal, in consequence of a disturbance, soon made movements and tried to get upon its
feet, most of the eggs were left at the bottom of the aquarium, and only a small number were already

so firmly fixed that they clung to the swimming feet.”

48 BULLETIN OF THE UNITED STATES FISH COMMISSION.

the eggs had not yet broken down. The ovary of the larger lobster was similar to
this, but the process of histolysis had not advanced quite so far.

The eggs are sometimes absorbed under natural conditions, but why this happens
is not understood. A very interesting illustration of this fact came to hand on July
16, 1894, when, on account of its very dark color, my attention was directed to a
hard-shell female lobster, about 11 inches long. The membranes of the joints of the
limbs and under surface of the body were of a dull-green color, very unlike the
appearance which these parts assume in a molting lobster. Examination showed
that the ovarian eggs were almost completely absorbed and that the blood of the
animal had a very distinct greenish tinge. The ovary was of a bright lemon-yellow
tint, the color of the degenerated eggs, flecked lightly with green, where an egg had
not lost its normal appearance. The ovarian lobe had shrunken to less than one-half
its former size. The green pigment which was dissolved in the blood had undoubtedly
come from the eggs, and had been taken up into the blood faster than it could be
eliminated from it. I was told by Professor Ryder that the ovarian eggs of the
sturgeon are sometimes absorbed in a similar way, and the same phenomenon is
probably met with throughout the animal series.

In the lobster there are always a few ripe ovarian eggs which fail of extrusion at
the proper time, which are invariably absorbed and give to the mature ovary at the
next reproductive period a characteristic appearance. (See p. 69 and plate 38,
fig. 136.)

One of the females which laid eggs had been kept by herself for several weeks.
When discovered, on August 24, the ova were in an advanced stage of yolk segmen-
tation. They were somewhat undersized and of a peculiar light-grayish color. The
eges were fertile, although the segmentation was generally abnormal. The lobster,
which was placed in an aquarium on July 50, was found to have external eggs on the
11th of August, in a very early stage of development. They had probably been
extruded during the previous night. These eggs were rapidly attacked by fungi and
their development was retarded in consequence. Long fungoid filaments grew over
the surface of the eggs, and diatoms attached themselves in great numbers to the
egg-capsule. The eggs of lobsters taken under natural conditions are always clean
and, so far as I have observed, free from vegetable growths of every kind.

The eggs are fertilized after ejection from the oviducts by the spermatozoa, a
supply of which is always stored up in the seminal receptacle of the female. There is no
internal copulation, and no possibility of an internal fertilization in either the ovaries
or their ducts, as already explained (p.39). The ova are probably immersed as soon as
they are extruded, in a liquid cement substance, which is secreted in special glands
situated inthe swimmerets of the female. The ‘“ tail” is folded so as to form a closed
pouch or chamber, as has been observed in the crayfish and other decapods (see
note 1, p. 47), and the eggs received within it are mixed with the liquid cement and
sea water. Fixation to the hairs of the swimmerets is finally effected by means of the
cement, which gradually hardens. How the sperm cells are conveyed from their
receptacle to the eggs, whether through the medium of the sea water or the glue, or
whether or not by a motion of their own, is not definitely known. (Page 34, note 1.)

That the cement is incapable of fixing and holding the eggs until after exposure
to sea water for some time (perhaps a few hours) was shown in the case of a lobster

sr

THE AMERICAN LOBSTER. 49

taken from the well of a fishing smack, after extrusion had been partially accomplished,
at Rockland, Maine, August 6, 1893. The lobster, I was told, was taken out and laid
on the deck, when the soft. dark-green mass of eggs began to flow away from the body
from their own weight. (Compare note 1, p. 47.)

Cano (32) gives the following detailed account of the laying of the eggs in the
crab Maia:

The time that intervenes between copulation and the deposit of the eggs may be eight, ten, fifteen
days, or even longer, and can not be fixed, since copulation happens before the eggs mature in the
ovary. The eggs, at the time of ovulation, pass the opening of the receptaculum seminis, and are here
invested with a coat of cement, which is secreted and held in the receptacle. The eggs then revolve
on their axes in the vaginal canal, and are expelled, one at a time, by means of the valvular apparatus.
This is formed by a prolapsus of the vaginal canal. ~ * * Besides the proper muscles of this canal
there exist special muscles which, by lowering the membranous covering, provoke the expulsion of
the eggs through the valvular orifice. The eggs thus ejected fall into the abdominal chamber. The
female beats them about with repeated blows of the tail, while the pleopods, keeping them in
continued agitation, make them converge toward the center of the abdominal pouch. The deposition
of eggs is effected in Maia in the course of twenty-four hours, but sometimes in Lissa it takes a longer
time. On the next day all the eggs adhere in groups, by means of one or two peduncles, to the hairs
of the internal branches of the pleopods, while the external branch agitates them continuously.
This movement, besides renewing the surrounding water, probably assists in rupturing the egg shell,
when the embryos are ready to hatch. Fixation could not be explained without the interaction of
the sea water. The cement at first becomes more viscous, then hardens and forms a very thin pellicle,
which, with the growth of the embryo, becomes quite hard and resistant. It would seem that the sea
water might explain the chemical change which the cement undergoes, a change analogous to that
which is observed in the exoskeleton after the molt. The cement may be regarded as a substance
very like chitin, both being of ectodermic origin. The cement serves not only for fixation, but
unquestionably as the vehicle of the seminal elements toward the eggs.

If we examine the zone of cement which invests the eggs at the moment the latter traverse the
short vaginal canal, there is seen a large quantity of seminal corpuscles, some of these still in the
spermatophoral envelope, others free and swimming in the homogeneous mucus. These vary both in
shape and dimensions. All the elements are immobile, but once I noticed that some of these cells,
especially those with radial prolongations, were endowed with ameboid movements. Whether these
movements are the same as those which impel the sperm into the egg I can not say from direct observa-
tion. The question then remains open as to when and how the spermatozoa pass into the eggs, which are
unprovided with a micropyle. If they are able to penetrate through the poral canals of the chorion,
and if this penetration can happen during the very brief passage of the egg through the vaginal
canal or at the moment of deposition of the eggs, as in the Macrura, then the sea water must exert
unknown physico-chemical actions on the cement, which makes the egg itself adhere later to the hairs
of the pleopods.

The typical phenomena of fecundation—the expulsion of the polar bodies and formation of
pronuclei—I have not been able to observe directly.

When the eggs have reached the receptaculum seminis the nucleus has become invisible. The
first segmentation nuclei are found in the central part of the eggs and move toward the periphery.
Segmentation begins almost as soon as the eggs are fixed.

Cano (33) observed cases in Carcinus and Portunus where the eggs were laid at
different periods, one-third of the eggs being in the morula stage and the rest ready
to hatch. Again, it was rarely found that the eggs were laid just before the molt, in
which case they were cast off and destroyed. This anomalous condition was first
noticed by Lo Bianco in Palinurus (18).

F.C. B.1895—4

50 BULLETIN OF THE UNITED STATES FISH COMMISSION.

NUMBER OF EGGS LAID AND THE LAW OF PRODUCTION.

The production of ova among animals is directly correlated with the condition of
the young at the time of hatching. Where eggs are very small and present in large
numbers, as in some of the crabs, we may look for a long larval period; when the ova
attain a much greater size and are at the same time very abundant, as in the lobster,
we find the larval period abbreviated; in other cases, as in some shrimps, where eggs
are relatively very large and few, the young hatch with the external characteristics of
the adult.

The production of a large number of eggs always means great destruction under
natural conditions. In such cases, however, the opportunity is afforded of increasing
the supply of adults, provided we are able to tide the larve over their earlier stages
of development. The number of eggs produced by the lobster is thus a subject which
deserves careful attention in view of its economic bearings alone.

The numbers here recorded are based upon the records kept at the United States
Fish Commission station. The eggs of each individual were carefully removed from
the “tail” of the female lobster and measured in a graduate (having sloping sides),
and the whole number of ova was estimated on the basis of the number contained in a
fluid ounce. ,.Mr. Edwards found the number of new eggs in one fluid ounce to be about
6,440 (in one ounce 6,461, in another 6,419), and the number of old or well-developed
eggs in an ounce to be 6,090. This is a relatively rough method of determination, and
the results are of course only approximately accurate.

I estimated by weight the number of fresh eggs carried by a lobster 13 inches long
to be 17,623; total weight of eggs, 54.9 grams; number of living eggs to the gram, 321.
These ege’s were in an early stage of development.

The number of eggs borne by a large and a small lobster, carefully determined
both by the wet and dry methods by my assistant, Mr. I’. C. Waite, 1s given in the
following table:

TABLE 14.—The production of eggs determined by different methods.

| Lobster No. 69,

Lobster No. 51, table 20; from

Observations. table 20; from

at , Woods Hole

Gay Head. aaron
Stage of development of eggs......-..--.-.-----.. Late segmen- | Post-nauplius;

tation. about three

weeks old.

Length of Jobster in inches....-.......--------+-- 153 93
Number of eggs to the gram ‘1).-- 815 1, 009
Weight of 1,000 eggs in grams (0) - 1, 2255 0. 9893
Total weight of eggs in grams ---- 68. 8092 10. 4029
Number of eggs to the c.c. (¢, ..-- a 220 211
Number of eggs to the flnid ounce .-..-.-: Tene ee 6, 248 5, 992
Number of eggs determined by the dry method (a). 56, 079 10, 507
Number of eggs determined by the dry method (b) - 56, 148 10, 514
Number of eggs determined by the wet method (c) - 58, 500 10, 919

Mr. Waite estimated the number of eggs in a fluid ounce (on the basis of 2,110
to 10 ¢.c., the number obtained by count) to be 5,992. These eggs had been in strong
alcohol for upwards of three years. They were about three weeks old when preserved,
and in alcohol had an average diameter of 1.625 mm. (1.56, 1.69 mm.)

In the wet method (c) employed, the number of eggs was estimated upon the
actual number, obtained by counting, in 10 ¢, ¢. In the dry method the number was

THE AMERICAN LOBSTER. 51

determined either (a) on the basis of the number of eggs to the grain, or (b) by the weight
of 1,000 eggs. The numbers obtained by the last two methods agree very closely, and
it is plain that the dry method is the most reliable. The wet method gives a number
which is from 3 to 4 per cent greater than that obtained by the dry method. There
is probably a constant error of this amount in the wet method,! and this slight error is
due to the presence of the stalk of the secondary egg sane ING, which has a tendency
to keep the wet eggs apart, but which shrivels and cracks off “alban dry. It increases
the buoyancy of the fresh eggs and is the cause of the bunching commonly observed.
The excess due to the bunching of the eggs is about 0.3 per cent. This source of error
was eliminated in No. 69 of the table, where the eggs were separated with needles
before measuring.

THE LAW OF PRODUCTION,

In table 15 I have reduced the results of a very large number of observations
made upon lobsters varying from 8 to 19 inches in length. The total number examined
is 4,645. Of these, 1,678 were taken on the ledges 15 miles southwest of No Man’s Land
Island from April 20 to June 16,1894. The remaining 2,967 were captured in Vineyard
Sound and in the vicinity of the Klizabeth Islands fom April to June, 1889-94, A
smaller number were taken in February during the same years. The eggs went to
Supply the hatchery of the United States Fish Commission.

TABLE 15.—Production of eggs.

| « = | 2 TI | Pail
M | Smallest | Largest | Average | Number of Sie’. Smallest | Largest Average Number of
pone tbicr | number number | number lobsters Tene ch of number number number — lobsters
ag of eggs. of eggs.) of eggs. | examined. as of eggs. | of eggs. | of eggs. examined. |
| e |
8 inches..-. 3, 045 | 9, 185 | 4, 822 6 13 inches..-... 6, 090 48,720 | 28,610 321
84 inches. --- 6, 090 7.612 6, 851 2 || 134imches..-.. 24, 360 48, 720 | 33, 495 | 5
Skinches....| 3,045 | 12,180 | 6, 935 9 || 134inches..--. 6,090 | 54,810 | 32, 858 | 146
$ inches. .../ 6, 090 | 9, 135 | 7, 105 3 || 132inches..... 42, 630 42,630 | 42,630 | 2
9 inches.... 3,045 | 18,270 7, 902 143 14 inches..... 6, 090 85, 260 36, 960 | 426
94 inches. ...| 6, 090 12, 180 9, 083 35 || 14hinches-.... 21,315 60, 900 42,968 | 90
a ches ee s hae | 20, 792 | a Fe 241 || 13! nen Soace 12, 180 97, 440 ao ae | ze
inches.... , 045 | , 220 | 947 55 PINCH eSessan| eee eases 54, |
10 inches--... 3,045 | 24, 360 10, 555 514 |) 154 inches...-.. 24, 360 53, 795 45 |
104 inches. --. 6,090 | 22,838 | 11.622 61 || 152inches..--. | 48, 720 50, 750 3 |
GbincHes|=) aco| 24's00| acoer| “ar. || ton epeeecs-7] 780? | 66990)
#inches.... , 090 | No , 06 5 4 inches...-. BaEoese fem pasaneeous 3, 990 |
i inches....! 3,045 | 48,720] 15,410 568 163 j inches..... 36, 540 | 66, 053 | 13
11d inches. -.. 6,090 | 25,882; 17,102 43 17 inches..... 12, 186 63, 836 30)
113 inches. - --| 3,045 | 42,630 | 18, 668 307 174 inches..... | 60, 900 73, 080 64, 960 3
11} inches Seoe|| 12,180 | 24, 360 Sth 993 LS | eL'S) anche -| 60,900 91, 350 77,430 | if
12 inches.... 3, 045 54,810 | 21,351 | 414 || 19 inches...-. 54, 810 91, 350 77, 647 4
124 TiGhesmeal 18, 270 | 27,405 | 23, 396 | 8 ; |——
124 inches. .-. 9,135 | 42,630 | 24,812 156 ‘Total number examined............. ... 4, 645
123 inches. -.. 18, 270 .42,630 | 26,390 12
| | | |

The average number of eggs of a lobster Of a given length has little value unless
obtained from a large number of individuals. While the small number of eges
occasionally recorded for lobsters over 12 inches long may be the result of loss, in
lobsters under this size it is probably, more often due to belated sexual maturity.

' This excess will probably about offset the erent ieee of eges en wens olen occur. The
numbers given in table 15 do not therefore require correction on this account,

52 BULLETIN OF THE UNITED STATES FISH COMMISSION.

In casting the eye down the column of averages! in table 15, we are immediately
struck by the fact that a 10-inch lobster bears about twice as many eggs as one 8
inches long, and that a 12-inch lobster has double the number borne by one which
measures 10 inches.

It is therefore suggested that in the early years of sexual vigor there is a general
law of fecundity or production which may be formulated in this way: The numbers of
eggs produced by female lobsters at each reproductive period vary in a geometrical series,
while the lengths of the lobsters producing these eggs vary in an arithmetical series. Itis
safe to assume that the avearge number of eggs laid by a lobster 8 inches long is not
above 5,000. If such a law prevails we would have the following:

| Terms. | (1) | (2) M1 OG | @ | (6)
| Seecceeteeneric BAA at [sn oe eee, | Mees Eo
—— | | |
Series of lengths in inches. . 8 10 12 | 14 | 16 18 |
Series of eggs .---.--..--.--| 5:000 | 10, 000 20, 000 40,000 | 80, 000 | 160, 000
|

| |
i i

An examination of table 15 shows how closely the first four terms of this series
are represented in nature, and that when the 14 to 16 inch limit is reached, there is a
decline in sexual vigor. Yet the largest number of eggs recorded for lobsters of

Length of

animal in inches
8B

16

14.

12

10

0 /\ 10000 20000 30000 49000 50000 60000 70000 80000 Eggs
ba

Cuv 1.—Curve of fecundity of the lobster.

1 division on ordinate corresponds to 2 inches in length of iobster. 1 smaller division on abscissa represents 1,000 eggs.
aa, curve deduced from law of production as theoretically stated.

6b, curve of fecundity deduced from observations recorded in table 15, for lobsters 8, 10, 12, 14, and 16 inches long.

this size shows that there is a tendency to maintain this high standard of production
even at an advanced stage of sexual life.

‘It is a conspicuous fact that in the fifth column of table 15 the largest numbers refer to
individuals whose length is expressed in even inches or half inches. This is of course the result
of inaccuracy in taking measurements: the quarters have been somewhat neglected.

THE AMERICAN LOBSTER. ays}

A graphic representation of the fecundity of the lobster tells more e forcibly than
words or figures can how closely it is in conformity with the law just enunciated. If
a curve is constructed in accordance with the latter, we obtain, as in cut 1, the curve
aa, Which is the wing of a parabola. Neglecting for the present all data in table 15
but those corresponding to the arithmetical series of lengths, 8, 10, 12, 14, 16 inches, we
obtain the curve of fecundity represented by the dotted line bb, cut 1. This curve is
parabolic and follows the curve aa with remarkable uniformity up to the region of the
fourth term, where the ratio of production is distinctly lessened. This becomes still
more marked in the fifth and sixth terms.

In cut 2 the details of the curve bb are given, including all the data of the table.
We see in the line bb! the same remarkable conformity to “ine parabolic curve required
by the law. Beyond the fourth term (length 14 inches) the irregularities in the curve
become greatest, owing to the small number of individuals represented.

I believe the law above formulated expresses the propagative powers of the lobster
during the height of its sexual activity, although it must not be supposed that the
latter conforms uniformly to any arithmetical standard.

Length of

animal in inches b?

18

UG,

16

15

14

13

8 piitititiiitiiy
Oo ;\10000 20000 30000 40000 50000 60000 70000 80000 Eggs
ba
Cur 2.—Curve of fecundity of the lobster.

4 smaller divisions on ordinate correspond to 1 inch in length of lobster. 1 smaller division on abscissa represents
1,000 eggs.

aa', curve deduced from law of production as theoretically stated.

bb!, curve of fecundity deduced from all the data contained in table 15, or from number of eggs produced by 4,645
lobsters.

After the lobster has reached a certain age, determined by its early or late sexual
maturity, its reproductive energy tends to decline, as is the case with the higher
animals, and the ratio of increase, maintained at an earlier period, begins to fall.
Whether the highest point of production is ever reached at 14 or 16 inches it is

54 BULLETIN OF THE UNITED STATES FISH COMMISSION.

difficult to say, and whether the sexual decline is gradual or not it is impossible to
decide from the data at hand. In this connection, however, it is interesting to recall
the fact that the male lobster attains greater size than the female. The large lobsters,
weighing upward of 20 pounds and measuring upward of 20 inches in length, are
invariably males, so far as my observation extends.

The largest egg-bearing lobsters of which I have any record were taken 15 miles
southwest of No Man’s Land, June 9, 1894, and examined by Vinal N. Edwards. One
19 inches long, carried 91,350 eggs, which weighed 15 ounces; another, 16 inches in
length, bore 97,440 eggs, which measured 16 fluid ounces and weighed nearly a
pound. Mr. Edwards said that the mass of eggs was in these cases so great that the
animals were unable to completely fold their “tails.” (See p. 34.) A lobster with
external eggs was taken at Green Island, Maine, in November, 1892, which, according
to Mr. F. W. Collins, weighed 184 pounds.

Individuals

120,

10.
100

95 amas
90 ] aes =
ot

a
75

70 i aes Bee
oe Se
60

zi Soe
50

“5 a SY

ve ee ee eae ee)
35 [aioe eal
30 [eee
: a
20 | ETN

15 Weise si
° Ve
eal ! |

4000 5000 10000 15000 20000 25000 Eggs.

Cur 3.— Curve showing the relative fecundity of 352 lobsters, each 10 inches long.

Number of individuals laid off on ordinate.
Number of eggs laid off on abscissa.

The No Man’s Land lobsters seemed to carry rather more eggs than those of the
same length captured elsewhere. Thus 234 lobsters, 13 inches long, from No Man’s
Land produced on the average 29,526 eggs (extremes 6,090-48,720), while for 79
lobsters caught elsewhere the average production was 26,518 (extremes as above).
The small number examined in the last instance shows, however, that the comparison
has little or no value.

The variation in the number of eggs borne by lobsters of the same length is often
very great, and is as marked in large as in small individuals. Thus in 152 cases the
average production of 10-inch lobsters was about 11,000 eggs (the average in 552
cases, table 15, is nearly 13,000); 32 per cent of this number bore from 12,000 to 13,000

THE AMERICAN LOBSTER. 55

eges; 15 per cent carried from 15,000 to 16,000; 6 per cent had 18,000 to 19,000; one
individual carried upward of 21,000, while 4.6 per cent bore only 3,000 to 4,000. This
is further illustrated by cut 3, which shows the variation in fecundity of 352 lobsters
each 10 inches long. In this case 26 per cent laid 9,000 eggs, 30 per cent 12,000, not quite
1 per cent 18,000. The curve drops and keeps well down after the 12,000 limit is
reached, which possibly implies a loss of eggs in those lobsters having more than the
average number.

TABLE 16.—Production of eggs by volume.

| Smallest | Largest | Average 7 Smallest | Largest | Average E
Length number | number | number pines | Length number | number aa pores

of lobster. of fluid | of fluid | of fluid | 0% (00S ean of lobster. of fluid | of fluid | of fluid | °® pos. one

ounces. | ounces. | ounces. | °X#™mneC. ounces. | ounces. | ounces. | CS Ned.
8 inches..... 4 1s -78 6 | 13 inches..... 1 8 4.70 321
8iinches..... 1 14 1.12 2) 13,inches...-.. 4 8 5. 50 5
8} inches 4 2 1.14 9 | 13} inches. 1 9 5. 39 146
8} inches 1 14 1.17 3 | 13} inches. 7 7 7.00 | 2
9 inches-..-... 4 3 1.30 143 | 14 inches..... 1 14 6.07 426
94 inches..--. 1 2 1. 50 35 | 144 inches..--. 3h 10 7.05 90
92 inches. - --- 4 34 1.53 241 | 15 imches....- 2 16 7. 64 280
92 inches..--. 3 24 1. 63 DO meLoanc hese ees | eerie seers | seven oeine 9. 00 1
10 inches..--- 3 4 1.73 514 | 153 inches..-... 4 16 8. 83 45
103 inches...-- 1 33 1291 61 | 152 inches....- 8 9 8.41 3
103 inches. - -- - 3 6 2. 12 532 || 16 inches..... 4 16 9. 38 103
10% inches-.---- 1 4 2.31 Z| TIGEURT OER Ggoed bosedosaed boouaceeee 11. 00 1
11 inches..--. 4 8 2. 53 568 || 164 inches..--- 6 14 10. 85 13
114 inches..---- 1 44 2.79 43 || 17 inches...--- 2 14 10. 40 30
11$ inches..--. 4 7 3. 06 307 | 174 inches-.-.. 10 12 10. 67 3
11§ inches-..-. 2 4 2.95 S| Sin ches®. <2. 10 15 12.71 7
12 inches..... 4 9 3.51 414 | 19 inches-..... 9 15 12. 75 4

124 inches..--. 3 43 3. 84 8 —————
124 inches... -.. 14 vi 4. 07 156 Total number examined..-.-.-.....-...-- 4, 645

123 inches..... 3 7 4.34 12 ||

The data collected in table 16 will show in still another way the variation in the
quantity of eggs produced by lobsters of different sizes. The average weight of a
104-inch female lobster with eggs is 13 pounds (table 31), the eggs weighing about
2 ounces. A 15-inch lobster which weighs upward of 4 pounds (table 31), sometimes
carries a burden of a pound of eggs. As already remarked, a fluid ounce of fresh
eggs weighs about 1 ounce avoirdupois.

PERIOD OF INCUBATION AT WOODS HOLE AND RATE OF DEVELOPMENT.

The freshly laid eggs are somewhat irregular in shape, but soon plump out and
become nearly spherical. Some, however, have the form of elongated spheroids (plate
17, fig. 24). They measure approximately ~; inch in diameter, or 1.5 to 1.7 mm. In
color they are dark olive-green,! sometimes almost black, hence the use of the term
“black egg-lobster,” common among fishermen, to distinguish the ‘“‘new egg-lobster”
from the “old” or the “light egg-lobster,” in which the dark-green food yolk has
been more or less absorbed by the growing embryo. In England the female lobster
with external eggs is spoken of as being ‘‘in berry,” or is sometimes called a ‘“ berried
hen.”

The rate of development of the summer eggs at Woods Hole is illustrated by
tables 17 and 18, and by cuts 23-38 (plates G to J).

5 ' For variation in the color of the egg, see p. 137, and plate 17, figs. 23 and 24.

56

BULLETIN OF THE UNITED STATES FISH COMMISSION.

TABLE 17.—The rate of development of the embryo at Woods Hole.

| Tempera-| Age
| No Divs) |, Hour: ture of f § | Stage of development. Remarks.
| water. | % ©88- ;
| |
|
1890. | ON Hours. |
1(1) | July 3 1.45 p.m. 72 8(2) Yolkunsegmented..-.| 2 to 4 cells present.
| 1(2) |-2-do..-.| 6.00p.m. 72 ie \eaopd GI ganebausescedaee
1 (3) |---do ..-.| 10.00 p.m. 72 Gls estetee OO ieee res Soe eee
1 (4) | July 31 | 10.00a.m. 72 282 Segmentation of yolk., Few eggs only, with yolk unsegmented.
1 (5) |...do.---| 2.00p.m. 72 ByPe eens LOR eae as ae | Very few eggs still with yolk unsegmented.
1 (6) |-.-do-...| 6.00p.m. 72 363 een GU) Seosceosecoonses Several stages of yolk segmentation, some
eggs with about 30 segments; others with
very small and numerous cells; in a few
| eggs yolk still unsegmented.
| 1 (7) | Aug. 1] 9.30a.m. 72 EMS \heooe Gy cinodpsasseccous Majority of eggs with at least 160 segments ;
| : | some with irregular segmentation; some
with yolk nou-segmented.
1(8) | Aug. 2 | 12.00 m. 72 EL Wekbod Chi}igeocueabudsoraue Majority of eggs with periphered layer of
| | very small cells; rarely an egg with unseg-
| mented yolk.
1(9) ; Aug. 3 | 11.00 a.m. 72 1002 Invagination ...-..... Majority of eggs in this stage.
1889.
2(1) | July 11) 5.30p.m. 68% olin: ceeeece Segmentation of yolk.) Late stage, about equivalent to 1 (7) above;
| cells not quite superficial.
2(2) | July 12!) 9.30 a.m. 68 16 + |..--- Gly) Seesesouascssabe Protoplasm generally at surface, and cells
| | most numerous on one side of egg.
2(3) | July 13) 1.00p.m. 69 433+ Invagination .......--
2(4) | July 14) 5.45p.m. 69 724+ .---- i Oieeeepracdadecsoa Pit at surface.
2(5) | July 18 9.50 a.m. 68 160234 ---.. (Wepeiaancnescacseos Depression on surface very marked.
2 (6) | July 19 | 12.20p.m. 68 17434 \.--.- GU) Seasnaesechosdns Nauplius embryo not yet outlined.
TABLE 18.—Rate of development of the embryo at Woods Hole.
leniperas| Stage of devel
No. Day. Hour. ture of | Age of egg. rea MeO. Remarks.
water. :
1890. |) kee Days. Hrs.
3 (1) | July 9) 3.45 p.m. 71 8 3(2) Invagination .....| Pit at surface very conspicuous. See cut 25.
3 (2) | July 11 | 12.45 p. m. | 69 10 Egg-nauplius...-.. In some eggs, second antennz not budded.
3 (3) | July 15 | 10.30a.m.) 69 14 De eesti) eeonpctinacan Second antennx bifid; thoracic abdominal |
| | fold formed. See cut 31. |
| 8 (4) | July 17 | 12 m. | 70 16 BES Spence (Wrocbsceseace= Late egg-nauplius. See cut 32.
3 (5) | July 22 | 12 m. | 70 21 33 | Post-nanplius ....) 4 to 5 pairs of post-mandibular appendages;
| | tip of ‘‘tail’’ conspicuously forked; optic
disks lobular. Cut 34,
| 3 (6) |...do-.-.| 10.30 a. m. 69 24 Pe | LaodsamsscbboDacocs Optic lobes very large; telson overlaps
brain; 6 or 7 pairs of post-mandibular
| appendages; antenna and telson tipped
| with rudimentary setz.
BY (i) ainlby PP liesececcoaaos 70 26 OE nc Ssacooscqnesneaect Telson reaches base of optic lobes.
| 8 (8) | July 29) Sp.m 71 28 (Fb |esctpochbonaeaonsace mye pigment present for about 24 hours.
| | ut 35.
3 (9) | Aug. 3 | 10.30 a. m. | 72 | 33 DO pigel | Wee eeer iene caer Eye-spots crescentic or semicircular; telson
| overlaps bases of optic lobes.
$ (10) |-Aug.12 |} 12.30p.m.| 72 | 42 16} |..-----.-...------:. Eye-spots oval; telson considerably behind
| optic lobes.
S(GG5) Seb al esSsuscacesllescadsoose Gill pe Sere e anos sees | See drawing, cut 36.
SGD) |} Oi 0 ke bensaecos sed beaskusoss = Print WN | wills eae rater
BU(GIBIY WON eh ajn ied 6h cea areeel eSeaee as = PRS «|e eae ocddeopeeaacicc | See drawing, cut 37.
8} (05) || TOY ey, | Bebneae Sead scoaseaee = [STDOPE piel See comer
3 (15) |
3 (16) | See drawing, cut 38.
3 (17)
3 (18)
Bi (19 yc May 1s |b goce et] Goa 256. B08 eee emma | neni sree een
3 (20) | | Larvee hatching out.

The lobster (No. 3, table 18) which laid eggs about July 1, 1890, was kept under
observation at the Fish Commission station at Woods Hole for a period of 11 months
or 334 days, until June, 1891, when, as we see, the eggs had begun to hatch. Under
natural conditions the period of incubation of the summer eggs at Woods Hole is

nearer 10 months—(from July 16th-August 15 to May 15-June 15).

THE AMERICAN LOBSTER. Di
The very fresh eggs can be usually detected by examination with a hand lens.
The transparent egg capsule closely invests the yolk, which then presents a uniform,
tinely granular texture. The external segmentation of the yolk follows in twenty to
twenty-five hours after oviposition, and the large yolk-segments can be easily distin-
guished by the naked eye. At the close of this process, or after the invagination has
begun, the living egg, when examined with a low power, resembles the fresh egg,
excepting that the yolk has now a coarser and more irregular texture. The embryo is
distinctly marked off in the egg-nauplius stage in about ten days, and when from
twenty-six to twenty-eight days old the eye pigment can be seen at the surface.

THE HATCHING OF THE EGGS.

THE HATCHING OF LOBSTERS AT WOODS HOLE.

We have seen that the period of incubation or fosterage lasts from ten to eleven
months in the case of the summer eggs. As yet nothing is known about the hatching
of the fall and winter eggs. The bulk of the eggs which are taken for the Woods Hole
hatchery complete their development in the McDonald jars in June, as shown in the
following table:

TABLE 19.—Time of' collection and hatching of the eggs of the lobster at the United States Fish Commission
station, Woods Hole, Massachusetts ; compiled from records of the station.

Time of collection of the eggs. Hatching begun. etcine PAST TO Tere,
1890. Apr. 16 to June 13; majority taken | May 17..---.----------------- June 23 | June.
in May.
189)0 Aipr-28) to/Jiune) 29. --- <5. --- 5.6... May 25 (eggs taken Apr. 28).| June 15 | June.
1891-1892. Dec. 1, 1891, to Apr. 28, 1892...| May 30 (eggs taken Apr. 25) -| June 29 | June.
1893. Apr. 19 to June 26...-............- Afi) ib) HSS oesssospoca]esbacs July 15 | June 15 to 30.

These results agree with what takes place in nature when the lobster is permitted
to keep her eggs for the full time. The eggs from several lobsters are usually placed in
a single jar, and the jars are replenished while the hatching goes on.’ The dates in
the second and third columns of table 19 therefore indicate the general range of the
hatching period, not that of the hatching of a single brood.

Lobsters with light eggs, or eggs of the previous summer, were last caught in
Vineyard Sound and vicinity in the summers of 1890 to 1893, at the following dates:

1890, July 9. One female lobster taken in Woods Hole Harbor with eggs hatching; several hundred
eggs not yet hatched.

1891, July 16. Six female lobsters, with nine-tenths of the eggs hatched, taken at Menemsha. On
July 11 a lobster was taken at that place with eggs in process of hatching, and on June
30 two lobsters with old eggs were caught in Woods Hole Harbor. In one of these the
eggs had begun to hatch; in the eggs of the other there was still considerable unabsorbed
yolk.

1892, June 28. Four lobsters with old eggs were taken.

1893, June 30. No lobsters with old eggs were taken at Menemsha after June 30. At this time they
had in the past few days obtained 16 lobsters with old eggs, and in half of these the eggs
had meantime hatched.

1894, July 14. A lobster was brought from Menemsha, having been caught some time before, with eggs
about four-fifths hatched out.

1The temperature of the water in the hatching jars in summer is about one degree higher than
that of the water outside.

55 BULLETIN OF THE UNITED STATES FISH COMMISSION.

The last lobsters with light eggs were taken by the Gay Head lobstermen in 1890,
July 7. This was also the date of the capture, at that point, of the first lobster with
new eggs.

The time occupied by the hatching of a single brood was upward of a week, in
the following case: On June 30, 1891, a lobster with old eggs, taken in Woods Hole
Harbor, was stripped, and the spawn was placed in a “‘MeDonald” jar. On July3 one
larva had appeared; by July 5 a dozen larve had been hatched; on the 13th of the
month hatching was still progressing slowly, and some of the young had molted and
were in the second stage.

In another lobster taken at Menemsha, July 11, 1891, with young just hatching
out, the eggs, treated in the same way, were nearly all hatched in one week’s time.
On July 12 a large number of the first larve were swimming about the jar, and on
July 18 the eggs were mostly hatched and many of the young were in the second
larval stage.

In July and August, 1892, Mr. A. P. Greenleaf placed 300 egg-lobsters from Nova
Scotia with newly laid eggs in one of the lobster pounds at Southport, Maine. In
April, 1893, he seined, and found the females still bearing eggs. He seined the pond
again in June, when it was evident that the larger part of the eggs had hatched.

Mr. Thomas Garrett, who began to fish for lobsters in the Vinal Haven Islands
over forty years ago, caught in July a large, old egg-lobster, which weighed about
6 pounds, in the “ Basin” near the present lobster park. He returned it to the water,
caught it a second time, liberated it again, and about the 1st of August caught it for
the third time, when the eggs had all hatched out

THE DISPERSAL OF THE YOUNG.

With the hatching of the young the period of fosterage comes to an end.' By the
fanning movements of her swimmerets the young are driven away from the body of
the mother as soon as the egg-membranes have burst and are immediately dispersed ;
thenceforth they lead a free and independent existence.

The hatching of the eggs of the lobster has been often witnessed by smackmen
and keepers of lobster pounds. In May, June, and July “the surface of the water in
the wells of the smacks often becomes perfectly alive with the young, and they may be

1 Nothing very definite seems to be known about the ovulation and hatching of the youngin
the European lobster, Astacus gammarus. Rathke’s observations in 1840 did not settle the question
(see p. 167), and Sars’s paper (275), published over thirty years later, left it still in doubt. Sars
says that ‘‘the reproduction of the lobster does not appear, as is generally held, to be confined to any
definite period of the year, yet the young are mostly hatched in summer. It is not unusual, however,
to find the lobster with external eggs at other times of the year.” Mayer (38) remarks that there is no
definite breeding season, but that Homarus (Astacus gammarus) and Palinurus extrude their eggs mostly
in November and December. These conflicting statements show that the European lobster carries her
external eggs for a long period, and I have no doubt that when this subject is carefully investigated
it will be found that the breeding habits of Astacus gammarus are very similar to those of the American
species.

When this work was in press and after the preceding note was written I received Dr. Khren-
baum’s paper, to which I have already referred (61). He says that the eggs are laid and the young
are hatched from about the mid@le of July to the middle of September. In one of two cases observed
the eggs were laid August 1, 1893, and the first larve hatched July 20, 1894; in the other, the eggs
were extruded August 28, 1893, and the larvie hatched July 21, 1894. The period of incubation is thus
about 11 months, as in the American form, and the times of the laying and hatching of the eggs in the
two species very nearly agree.

THE AMERICAN LOBSTER. 59

scooped up by the hundreds of thousands,” and, as Rathbun says (158, p. 32), “a sort of
transplanting of young lobsters has been going on along the New England coast, and
especially the southern portion of it, ever since the well-smack lobster trade began.”
As the vessels sail along, the newly hatched lobsters “work out through the holes in
the bottom of the well, and are thus constantly adding to the supply of the regions
through which the smacks pass.”

Peter Kalm relates in his Travels, under date of October, 1748, the following
interesting anecdote of the transplanting of lobsters around New York by the New
England fishing boats, which it seems carried wells:

Lobsters are likewise plentifully caught hereabouts, pickled much in the same way as oysters,
and sent to several places. I was told a very remarkable circumstance about these lobsters, and I have
afterwards frequently heard it mentioned. The coast of New York had already European inhabitants
for a considerable time, yet no lobsters were to be met with on that coast; and though the people
fished ever so often, they could never find any signs of lobsters being in this part of the sea. They
were, therefore, continually brought in great well boats from New England, where they are plentiful ;
but it happened that one of these well boats broke in pieces near Hell Gate, about 10 English miles
from New York, and all the lobsters in it got off. Since that time they have so multiplied in this part
of the sea that they are now caught in the greatest abundance. (208, vol. 1, pp. 240-241.)

It is well known that the crayfish protects her young after they are hatched and
carries them about under her tail, as Roesel so well described over a hundred years
ago. He says:

If the mother of these little crayfish, after they begin to stir about, becomes quiet with her food
at any time, or for some other reason sits still, they begin to move away from her somewhat and to
crawl about her, but if they spy out the slightest danger, or there is any unusual movement in the
water, it seems as if the mother called them back by a signal, for they all at once quickly return under
her tail and gather into a cluster again, and the mother hurries off with them to a place of safety as
fast as she can. After a few days, however, they gradually leave her. (169, p. 336.)

Huxley was the first to observe that the ends of the forceps or large claws of the
young crayfish are bent into ‘abruptly incurved hooks,” by means of which the young
cling to the mother. He says:

Immediately after the young are set free, they must instinctively bury the ends of their forceps
in the hardened egg glue which is smeared over the swimmerets, for they are all found to be holding
on in this manner. They exhibit very little movement, and they bear rough shaking or handling

without becoming detached, in consequence, I suppose, of the interlocking of the hooked ends of
the chele embedded in the egg glue. Even after the female has been plunged into alcohol the young

ond
remain attached. I have had a female, with young affixed in this manner, under observation for five

days, but none of them showed any signs of detaching themselves; and I am inclined to think that
they are set free only at the first molt, After this it would appear that the adhesion to the parent is
only temporary. (203, pp. 43-44.)

The young lobster has no organs for attaching itself to the mother. Its large claws
do not end in sharp hooks (fig. 33, plate 20), as in the crayfish, and when once set free, it
never again finds shelter under the body of the parent. I have noticed that the young
of Pontonia domestica (a delicate West Indian prawn, which lives as a commensal in
the shell of the Pinna), when hatched in an aquarium, usually keep together in a ball
or cluster, like a swarm of gnats, a habit which is doubtless shared by many of the
prawns, but they never seek protection from the mother, who lives in the mantie
chamber of the mollusk. Young lobsters which are hatched and kept in the aquarium
swarm up to the surface or go to the bottom of the jar when closely confined, but if
given greater liberty they tend to scatter. A swarming or gregarious habit would be
fatal to this species, on account of its inborn pugnacity and cannibalism.

60 BULLETIN OF THE UNITED STATES FISH COMMISSION.

Bell (14, pp. 248-249) has given the following account, furnished him by Mr. Peach,
of the way in which lobsters were supposed by fishermen to protect their young.
Hardly a word of it is true, but itis a good example of the pseudo-scientific literature
to which I have referred, and on this account is worth quoting:

I have heard the fishermen of Goram Haven say that they have seen in the summer, frequently,
the old lobsters with their young ones around them. Some of the young have been noticed six inches
long. One man noticed the old lobster with her head peeping from under a rock, the young ones playing
around her: she appeared to rattle her claws on the approach of the fisherman, and herself and young
took shelter under the rock; this rattling, no doubt, was to give the alarm. JI have heard this from
several, some very old men, who all speak to this without concert, and as a matter of course; and they
are men I can readily believe. :

Young lobsters 6 inches long hardly require protection; smaller ones (an inch
long) are rarely seen by fishermen, and old and young separate as soon as the latter
are hatched. .

The writer of a popular magazine article, in quoting a fisherman, thus speaks of
the habits of young iobsters:

The mother is often seen surrounded by baby lobsters a few inches in length, who take refuge
under her tail in case of danger. (The Lobster at Home, by William R. Bishop, Scribner’s Monthly,
vol. xx11, 1881, p. 212.)

Erdl (62) says of the green crab (Carcinus menas), that it often appears to play
with small, round stones and with empty snail shells, just as cats play with balls.
(“‘Manchmal scheint mit kleinen runden steinen, mit leeren Schneckenhiiusen wie die
Katzen mit den kugeln zu spielen.”) Here, doubtless, the writer was misled by his
imagination: in the former instance we have a popular error which seems to have
crossed the Atlantic Ocean with emigrants to the New World.

Of the hatching of the eggs of the European lobster, which were thought to be
laid in the sand by some of the older naturalists (see p. 36), Travis (197) curiously
remarks:

Though the ova are cast at all times of the year, they seem only to come to life during the warm
summer months of July and August. Great numbers of them may then be found, under the appear-

ance of tadpoles, swimming about the little pools left by the tides among the rocks, and many also
under their proper form, from half an inch to 4 inches in length.

VARIATIONS IN THE TIME OF HATCHING.

According to Mr. Nielsen, the hatching period of the lobster in Newfoundland
begins about the first week in July and continues until the 15th or 20th of August,
the majority of the eggs hatching from the 15th or 20th of July to the 20th of August.
It is thus from three to six weeks later than at Woods Hole, which is what we might
expect from the difference in the temperature of the ocean at these points. It is not
yet known to what extent the time of hatching and period of embryonic development
varies from the normal course at the most divergent points on the coast; but it would
not be surprising if young were hatched at almost any time from late summer until
spring, owing to the irregularity in the production of eggs already pointed out.

Mr. Nielsen hatched a number of lobsters in floating incubators during November
in Newfoundland, and Mr. Rathbun (158) gives the following account of the hatching of
some lobsters at the Woods Hole station by Capt. H. C. Chester, in November, 1885:

The eggs were detached from the lobster and placed in the “McDonald” jar November 5. They
began to hatch November 8, three days afterwards, and continued hatching for a few days longer, but

THE AMERICAN LOBSTER. 61

only about 50 young ones were observed. The remainder of the eggs are still in jars in good condi-
tion. A few of the embryos were transferred to an aquarium with running water, and others to a
small vessel in which there was no change of water. The former lived about 24 hours, the latter about
36 hours. The temperature of the water in the hatching jar November 5 was 54.3° F.; on the 6th,
55°; and on the 7th and 8th, 56°. * * * The conditions under which the eggs were kept were
perfectly normal, the water being of about the same temperature as that of the harbor outside.

Ihave learned of another very interesting case of the artificial hatching of the
eggs of the lobster out of the regular season. This happened during the latter part
of January and the first ten days of February, 1889, at the hatchery of the United
States Fish Commission at Ten Pound Island, Gloucester, Massachusetts. Mr. HK. M.
Robinson, to whom I am indebted for these facts, was at that time superintendent of
the station. He says that the eggs were clipped from the lobster at about Christmas
time, and suspended in aquaria through which sea water was constantly running.
The temperature of the water was very low, at least as low as 36° F., and as many as
10,000 lobsters were hatched under these conditions.

Mr. Nielsen, who visited the station at that time, corroborates this account, so
far as the actual hatching of young lobsters is concerned. He writes that he examined
with the microscope a young lobster which had been hatched on the day of his visit.
The larva had perished in breaking out of the egg and in passing its first molt, but
was perfectly developed in every way.

These facts clearly show that the hatching period varies in the same way that the
time of egg-laying varies. The one must be correlated with the other.

William H. Wheildon gives some interesting facts about the lobster in a short
paper published in 1875 (202), already referred to. He says:

In February of the present year we exhibited spawn in several stages of development from newly
laid eggs to the swimming larvie.

The fact that the lobsters are with eggs in every month of the year, and that young
sometimes make their appearance in winter and fall, does not prove, however, as this
writer, like so many others, inferred, that the animal has no particular breeding season,
but from these facts alone it would never have been possible to have arrived at a clear
understanding of the reproductive habits. To the circumstance that egg-lobsters are
taken at all seasons and often with eggs in very different stages of development is
due, more than to anything else, the confusion which had settled down upon this most
important phase in the life-history of this animal.

In the case of the lobsters hatched at Woods Hole in early November, 1885, the eggs
were probably laid in the late winter or spring of the same year. I have the record
of a lobster which had in all probability spawned as early as June 20 (table 3, No. 2).
Supposing these ova to have been extruded by the first week in June, they would
have had five months, including the warmest period of the year, for their development.
For five months, from the first of December to the first of May, the eggs are subjected
under natural conditions to a relatively low temperature, and their development is
greatly retarded. Consequently a batch of eggs which is extruded at the first or
middle of August and hatched in May or June following is not, in all probability,
subjected to a greater number of heat units than eggs which are laid in June and
hatched in November. The embryos grow very slowly during the winter months, but the
advancement may be sufficient, when development has already proceeded far enough
in the fall, to bring the embryo to the point of hatching under favorable circumstances
in winter.

62 BULLETIN OF THE UNITED STATES FISH COMMISSION.

DESTRUCTION OF THE EGG-LOBSTER AND ITS SPAWN.

The berried lobster has many enemies, of which man is the chief, but if we except
the latter, she seems to avoid them with remarkable skill. At least it is true that
during the long period in which the ova are carried the losses are relatively slight.
You detect but rarely a bad egg in the whole lot, and when, after ten months, the
mother’s fostering care is about to end, one is surprised to see how healthy every
egg appears and how few seem to have been torn off. I have found that lobsters will
scratch off and devour their own eggs when confined in aquaria; and we often see the
spider crab (Libinia canaliculata) industriously picking off its eggs, as if for its own
amusement, when it seems to have no lack of other food. The eel has a decided
partiality for the eggs of the lobster, but the cautious way in which she keeps her
tail folded up when crawling over the bottom, and the lightning-like speed with which
she can dart about when disturbed, must often circumvent her most wily adversary.
On July 5, 1890, I placed three egg-lobsters, from which I wished to obtain embryos in
progressive stages of development, in a small floating car. One of these was a large
perfect female, a second was a small perfect female, and a third was disabled by the
loss of its claws. The next morning I found that the smaller female lobster had been
killed and eaten. The large one had cut its body in two, at the junction of the “back”
and “tail,” and eels had eaten out the flesh and picked off nearly every egg, only two
or three being left. Iafterwards found that lobsters kept in a similar way were liable
to lose their eggs while still active, and the aggressor was undoubtedly the eel.

Fishermen have maintained (28, p. 11) that egg-lobsters, if put together, devour
each other’s eggs, but this is not true. At least I am certain that this never occurs
unless the lobster is first killed by its companions.

At Small Point, Maine, “berry” lobsters used to be considered the best kind of
bait for certain fish. The “tail” of the lobster was cut off, a part of the upper shell
removed, and the eggs left clinging to the under side. This practice was probably not
confined to a single locality.

The pernicious destruction of the egg or spawn-lobsters is wisely prohibited in
most of the States, and it is to be regretted that an attempt to enforce such a law has
not been made in the Maritime Provinces and in Europe. This should certainly be
done even if the law is often evaded, owing to the ease with which the eggs can be
seraped off with a mitten or brush.

Ignorance of the fact that the lobster carries her eggs for a long period has been
an element of confusion in the establishment of close seasons. Thus in Connecticut
the law of 1878 forbade the destruction of females with spawn from July 1 to July 15.
In Massachusetts, in 1880, the sale of females with eggs was prohibited during July.
In 1883 the Maine legislature made a close time for egg-bearing females from April | to
August 1; this was changed in 1885 to from October 1 to August 15. In both Maine
and Massachusetts it is now, as it should be, illegal to take spawn-lobsters at any time.

The destruction of the spawn of lobsters is a terrible waste of life, and this is of
itself sufficient reason for the adoption of any measure which may tend to lessen the
evil. In certain parts of England lobsters in berry have been considered as in the
very best condition for eating, and the eggs are highly prized for salad. On this
account and because it was thought too great a hardship to compel the fishermen to
throw back the ‘‘berried hens,” the commissioners were not inclined to recommend

THE AMERICAN LOBSTER. 63

any legislation on this point. The following extracts from the testimony relating to
this subject is interesting. A witness from London says (28):

There is a difficulty in throwing back the berried hens. They are generally worth twice as much
as any other lobsters. The spawn is bruised and put into sauce, and makes better sauce than the
lobster itself. In salads it is boiled, and sprinkled over the salad. It is a capital article of food.
The spawning hens are of value to the cooks, who won’t havys lobsters without spawn. The sale of
berried hens must not be prohibited, as it would be preventing the fishermen from taking the most
fish. The production of the lobster is so enormous that if a gauge were fixed the taking of a few
berried hens would make no appreciable difference. Berried hens are in the best possible condition
as food. ‘They form fresh spawn immediately after they have cast their spawn. If they have no spawn
outside, they are full of red coral inside.

In his Report on the Fisheries of Norfolk, Buckland (29) says:

The lobster is never so good as when in the condition of a berried hen. Berried hens occur most
frequently in April, May, and June. They begin to lose their berries about July, but still many
berried hens occur in July. The use of the berries is almost entirely devoted to cooking; they are
used in many preparations by the West End chefs, especially for coloring and enriching sauces. ‘The
“chefs” are also fond of coral out of the body of the lobster.

The evidence of a manager of a shellfish factory in the Haymarket is quoted as
follows (29):

Mr. Sheppard, who boils lobsters for Scotts’, at the top of the Haymarket, informs me that he has
taken from one lobster (weighing 3 to 3} pounds) 6 ounces of berries in the month of May. In August,
out of 100 lobsters he would not be able to get 6 ounces of eges from the whole. On the 5th of August
he had 26 crabs, not one of which carried any spawn. In the month of May a great proportion of
these 26 hen crabs would be full of sp:wn. The eggs from the berried hens are used for coloring
various sauces; the berries are often mashed up in the sauce, a little anchovy added, and then it
is called ‘‘lobster sauce.” In order to supply these eggs for sauce to the cooks, Mr. Sheppard has
collected in April and May from 14 to 18 pounds of lobster spawn. I find that there are 6,720 [eggs] in an
ounce of lobster spawn. Here, then, we have destroyed eggs which might have represented, say, in 16
pounds of eggs, no less than 1,720,320 lobsters. A very good substitute for lobster spawn could be
made by boiling logwood (!). He considers that all berried hens should be returned to the water all
the year round.

The number of eggs borne by the female lobster is considered on pp. 50-55. A
15-inch lobster sometimes carries nearly 100,000 eggs, which weigh a pound.

The reasons urged by the commissioners for not indorsing the recommendation to
prohibit the sale of berried lobsters are remarkable as examples of logic. Thus, they
said “if it were illegal to take berried lobsters it would not pay the fishermen in many
cases to pursue the lobster fishery. In the next place, the lobster, when berried, is
in the very best possible condition for food; and it would be as illogical, therefore, to
prohibit its capture as to prohibit the taking of full herrings.” Furthermore, it is said
that if the sale of berried lobsters were made illegal “the fishermen wouid probably
remove the berries. The berries would no longer be seen in the market, but berried
lobsters would be killed as much as ever. Berried lobsters are, it must be remembered,
especially valuable; the berries are in great demand for sauce and for garnish for fish
and salad.” (28, p. Xvi.) “Accordingly,” says a writer in the Quarterly Review (273),
““we must run the risk of exterminating a valuable animal to please our cooks.”

Mr. Buckland says again, in his Report on the Fisheries of Norfolk:

There are, I regret to say, many difficulties in the way of preventing berried hens being destroyed,
the principal one being that, unlike the salmon, lobsters when carrying eggs are at their very best for
human food. Notwithstanding this, it must be evident that the destruction of so many lobsters in
the form of eggs must of necessity greatly tend to produce that scarcity of lobsters which is now being
felt in the London and other markets.

64 BULLETIN OF THE UNITED STATES FISH COMMISSION.

The concession to the cooks contained in the previous extracts is no more defen-
sible than the idea that the lobster when in berry is necessarily at its best as an article
of food. The reviewer just referred to, thus speaks upon the latter point:

We were under the impression—a common one, we believe—that as the spawning season began
to come on all the food eaten went chiefly to aid the growth of the innumerable eggs in the female or
of the soft roe in the male.

Travis (191), writing in 1768 from Searborough—a place which still abounds in
lobsters—says :

It is a common mistake that a berried hen is always in perfection for the table. When her
berries appear large and brownish she will always be found exhausted, watery, and poor. * * *
Cock lobsters are in general better than hens in winter.

It should be borne in mind that there is no organic connection between the
external eggs, which are carried under the “tail,” of the lobster, any more than
there is between a plaster and the skin to which it is made to adhere by an adhesive
substance.

The case of the berried lobster and of the roe-herring are not strictly analogous,
since the lobster is carrying her eggs which have been extruded, perhaps months
before, while the herring is yet in the active process of producing the spawn within the
body.

One would suppose that the only time when the lobster could be compared as to
the effects of spawning with fish like the salmon would be for a short period after the
eggs were laid. But this is not exactly the case, and Travis was nearer right than
his successors, when he maintained that the egg-lobster was an inferior article of food.
The fact is that the egg-lobster is in poorer condition or weighs relatively less than
the female of the same length without eggs. This point is illustrated more fully in
another part of this work (see p. 119).

The lobster at the time of egg-laying is not in as poor condition, however, as the
shotted herring or the salinon, which at this period is worthless as food, and the
reason is plain. The ovary of the lobster ripens slowly during a period of at least
two years, and the production and emission of the eggs is not so severe a drain upon
its vitality as in the case of the fish. After the eggs have been laid for some time, the
lobster gains in flesh; the ovary resumes its slow growth, but it is a year before the
“coral” becomes very conspicuous. The testes, corresponding to the ‘‘soft roe” of
fishes, are always very small, and produce sperm, not at a particular period, as is the
case with many species of fish, but probably throughout the entire year. The time
when the adult lobster is in the poorest condition for food is when the animal is
getting ready to cast its shell, and for a few weeks after the molt while the new shell
is still soft.

The destruction of a few hundred thousand eggs, or even a few millions, would
have no appreciable effect upon the supply of lobsters at any point on the coast; but
where the practice of taking lobsters with eggsis general throughout the range of the
fishery, the total amount of ova or embryos which are thus killed is prodigious, and
can not fail to lessen the number of adults.

Pee ee ee ee a

THE AMERICAN LOBSTER.

PERIOD OF SEXUAL MATURITY.

To determine the size which is usually attained by the sexually mature lobster is
of the first importance in studying the economy of this animal. If the female lobster
is not allowed to reproduce at least once before she is caught and destroyed, a deple-
tion of the fishery must inevitably result.

In some of the States and in the Maritime Provinces of Great Britain, where
lobsters still abound, or were abundant in the past, protective laws have been enacted,
prescribing a definite limit to the length of marketable lobsters. In Newfoundland
this limit is set at9inches. (The Royal Gazette, May 27, 1893.) In Maine the limit is
placed at 9 inches for the months of May and June, and 104 inches for the remainder
of the year.!. In Massachusetts, New Hampshire, and New York the limit is fixed at
10 inches; in Rhode Island at 10, and in Connecticut at 6 inches. It is thus evident
that very uncertain and contrary opinions have been entertamed in regard to the
size which is reached by the sexually mature lobster. In order to settle this question
upon the solid ground of anatomy, and at the same time work out a number of other
problems relating to the reproductive organs, I made in the summer of 1890 a large
number of dissections, and have embodied some of the results in table 20,

TABLE 20.—General condition of the sexual organs, of theexternal and internal eggs, and of the shell in lobsters,
chiefly females, ranging from 2 to 16 inches in length, in June, July, and August.

Date of Condition of sexual

fhe Condition of swim-
No. | Sex. Length. capture. | Locality. organs. panera Remarks |
} | é =
) |
| | Inches. | _ 1890.
1| Female | 10}, June 28 Gay Head, | Ovary pea-greencolor; | With old eggs, | Shell hard. Compare
vock bot- | extendsnearlytoend | nowhatching. fig. 138, pl. 38.
| tom. of third abdominal |
segment. |
DW onetoaea | TOBY |e eaGna0s|lonace dojencnce Ovary nearlysripe;|Ox= face ene <-i- 2 ele 1 Oviducts not distended
| tends to end of third with eggs.
| | abdominal segment.
3 | Male... Sta ipeed omens | creer QO ccteae | Ductsof testes charged |.-....-..........---
' | | with ripe sperm. |
FEI) |) IOS socsescd poate aor booes QO) cords Ovaries pea-greencolor., All witholdeggs, The gluey threads still
| | | Compare fig. 138, pl | hatched this attached to the hairs
| 38. | year. of the swimmerets |
show conclusively
| | that young have been
| hatched this season. |
11-17 _do | a aa (Ut Ygaral Ree GMWesodes Ovaries approaching | Clean.-..--..----- All about to extrude
maturity. eggs this season. In |
| one case eggs nearly |
ripe. Size ofinternal
| | egg, 1.32 mm. |
18=21 | Male.--- ket Sos ieomaloadds dobre | Testes filled with solid |BacdomenosSCopaSscor | Spermat op hores—or |
| | masses of ripe sper- packages of sperm, |
| | matozoa, which are wrapped in a gelati-
| surrounded by a gela- nous substance—can
| tinous secretion. be pressed out of the
ducts.
22 Female - 11g. July 9) Menemsha, | Ovaries dirty, yellow Clean..-.....-...-. Apparent'y no young
| sand hot- color; very immature. hatched this year.
} tom. | Probably never sexu
| _ ally mature.
23) |oa (Olea. 1P25 | SC Meas eosoe (0) GdonGe Ovaries dark green; |..-.. (Ute eee noerion Hard shell.
| | nearly ripe. |
WA eat Waser u Sat ieee Bees ) S55ne Ovaries immature; ..... dolse veo ea | Do. |
| very light green.
PAH sc kiy seed NOAM ee do seias| niin 0). sesnen Ovaries dark green; |..... (Wi Ggoneeae nen | Do. |
| like No. 23. |
Gilead Oe 10 do. see COREE Ovary strawcolor;very ---.. i er Seer soee Animal not reached
immature. sexual maturity.

' The legislature amended this law in 1895, so that it is now ilegal to destroy lobsters measuring
less than 104 inches in length at any time of the year.

F.C. B. 1895——5

66

BULLETIN

OF THE UNITED

STATES FISH COMMISSION.

TABLE 20.—General condition of the sexual organs, of the external and internal eggs, etc.—Continued.

| No.

Date of

| Condition of sexual

Condition of swim-

| Sex. | Length. capture. Locality. organs. TAS, Remarks.
Inches. 1890.
27 | Female - 114 | July 9 | Menemsha, | Ovary nearlymature...|...---.-..------..-- Soft shell.
| sand bot-'
tom.

282260 Ole. = LOS} bse dOeee seers dowes-=- Ovary straw color; like | Clean .-.--.-.----- Has probably molted
No. 26. | this season.

291 eee Oe 11h Beed Oneee| sere dopeeaes Ovary very light green.| Old eggs, hatched Do.

this year :

BL) seattle LOS 2s COvaerse | sees dowesees | eeeer (GO Ssscucomnsshoanad Cleanwireee se asee Soft shell. Hatched

young beforemolting.
31-82 |...do.-.-| 10§, 104 |---do--..]..... OW cccneelbooed GS — San omedaaueeeudleaose GWrancncsoasset 0.

33) ese Or see IOS WeestWissedlcoune Gi Wieeseenl Bese BechcooeSHoH Brome oe Glueyesee sees sees Shell hard. Hatched
young, but has not
yet molted.

345). 200) snc OF 25-00 saenle eee domeesees Ovary nearly ripe...-.- Clean@ecersesee rns Hard shell.

35 |... do.... OP eset ccd sease d0yeesres Ovary light green; im- | Old eggs, just Do.

mature. hatched.
36)|/522do-22- 10S3|-2-dojsesa|s= =. doyeen: Ovary strawcolor;very | Clean ..----------- Fairly hard shell. An-
| immature. imal never sexually
mature.
BU |Soe0 eee TPs Peed ope ses |s eae dope==s= Ovary pea-green color.| Old eggs, hatched | Fairly hard shell.
| this year.

38) eedomeee 109) |Se-doteeasleecis dojerseee Ovary light green; im- | Ciean.........---- Soft shell; probably
mature. ‘ hatched old eggs and

molted this season.

BESO ee ae 16 | July 22 | Gay Head, | Ovary nearly ripe; ex- |.....do-.-...------ Hard shell. Ovary

rock bot- tends to end of third flecked with yellow

tom. abdominal segment. spots, the remains of
degenerated eggs be-
longing to last sexual
period.

405 Fed Ope: by esc oese sedox doyeasee- Ovary pea-green color.| Gluey; old eggs, | Hard shell. Degener-
hatched this ated old eggs in ovary
year. and oviduct.

41 | Male. ... 1035 se dower | sera (hy 366 boproneamocsosodasecsansa|secesssubeoanGuaene: Soft shell. Molted in

H car June 22,

42 | Female . (EE eect) Goaalanoee dolesreee | Ovary very small; | Smooth..-...-..-- Hard shell.

| } opaque white. |

43 | Male.-..| GP iseat 0) cabal leans (0) Sense MeStesmn0b oun diene eee ee eee ree
gross dissection.

Adee dower OF os AO ys cin.dl Seis sesselcteseis sais nee ee ema see eee eee tee: | Ce eee eee ree eee See drawing of repro-

| | ductive organs, fig.
| 120, pl. 36.
45 | Female |! (ee saceleasae GW eacnds Ovarylightsyellowishwlee-cesers= ss see eae Hard shell; immature.
| i white; extends to | Ovarian lobe, 3mm.
middle of second ab- in diameter.
dominal segment.

A |e soos gb ee Weeee wader dower Ovary opaque white; |2=:-eeeeceesee essa Hard shell. Ovarian
extends into third lobe 0.8 mm. in diam-
abdominal segment. eter.

CW eaetily) ane al edt bhcaccloastd dOjeemeee Ovary light fleshicolors) |=22----es2 ea oe Hard shell.

| extends to end of
third abdominal seg-
i ment.
AS) 2"do ees: by Ae aatt() saralsooos UW Gesane Ovaryeopaquemwhitess |bae-sereeee eee e see
! very immature; ex-
tends to end of third
abdominal segment.

49 12 2doe ss a | ae Cl Oleyerets ees IO coomasllaosce (WO sb osanssaeeboscas|acesuoomnsnbuqabomod

50} ee aclojeiae 1224 |ROn ly 298 eer domes re | Ovary light greenish | External eggs; | Hard shell. Degener-
white, flecked with embryos with ated old eggs in ovary

| orange. eye pigment. and oviduct.

Gil, eaGkis ee 153 (Wyeeorle ctbd GO oaonies Ovary opaque whitish, | External eggs in | Oviducts filled up to
with many mature late segmenta- external opening
unextruded eggs. tion stage; laid with ripe, unex-

about 3 days. truded eggs. For
number of eggs see
table 14.

GY. lena (eres IPT Bas) pAod Woeed domes Ovary soft, jelly-like; | External eggs in | Hard shell. A few un-
opaque dirty-white early segmenta- extruded eggs, with
color, flecked with tion; about 36 remains of cones
yellow and orange. hours old. ated ova of last sex-

ualperiod. Figs. 134,
136, pl. 38, and fig.
139, pl. 39.
ABS loaate Pace sLsT ary |PACT Ores erates does Ovary light pea green, | Smooth.-.-....-.-- Soft shell. Has proba-
; flecked with yellow. bly hatched and
molted this year.

baa seed Opes Oe eed Omer lasers Gogeceees Ovary very light pea )----.do-.-----..-2. Soft shell. Has proba
green. Ova very bly hatched external
small. eggs and molted.

ee eg eed a

— ee ee

THE AMERICAN LOBSTER. 67

TABLE 20.—General condition of the sexual organs, of the external and internal eggs, elc.—Continued.

Condition of sexual |Condition of swim-

Date of

No. Sex. Length. capture. Locality. organs. aI. Remarks.
Inches. 1890.

55 | Female - 10 Aug. 11} Gay Head, | Ovary olive green; di- | Smooth .....-..--- Soft shell. Probably
| i rock bot- ameter of ovarian has not hatched eggs
tom. egg more than half of this year ;would prob-
that of mature ovum. ably have laid eggs
for first time the next

summer.

5G leeedo ese IPFe I akygodd bones doyas= aa Ovary rather dark |.-..- OW opacoocccdse Soft shell. Has proba-
green, flecked with bly hatched eggs and

| yellow; about half molted this season.
| its size at maturity.
10 Ovary light pea green; !.---- GW cendessoacise Shell fairly hard. Has
small. possibly shed this
season; may or may
not have hatched ex-
| ternal eggs.

SS dome: IE eae) Sond bosses dopeese- Ovary cream color; | Clean............. Fairly hard shell. Ani-
small. mal not mature.

Bh) lemctyerae Olas CW) cédeloodccilt scoadicd|aseds GD eceescocvessaegds Do.

GOR ee -dOr =.= 10 fs |e22d0le- = Ovary light pea green. Soft shell. External

‘ eggs due in following
vear; not certain
| that young have been

hatched this year.

Glia doe) IDES |e eet he coog| boas Gk) Soeeae Ovary soft, grayish | With external | Soft shell.
white. eggs.

GPO. oe (i eece TPT ead Wenodlsccce (1) srcinbd Ovary green; diameter | Smooth, clean .-..) Soft shell. Probably
about one-half inch. hatched brood this

year.

CB 22a sec) 124) | Pee doers ser domes: Ovary soft, whitish...) External eggs in | Shell fairly hard.

egg -nauplius
stage.
(7 Une ee 1235 ee doen emer (Wen cacd|lasced (iWigpededascosseoone Externaleggs;in- | Soft shell.
| vagination stage.

(Hy) each eace| OP eo cose! cocct} Seca ncllscene cowerres Sach beoeosEd bobod (0) méaaddodoace Hard shell.

GGie doo. -s| Om See domeen| sees 0eeccrn | Ovary small; cream | Clean-............. | Animal not mature.

| | color.

6Gialeaedome | 1D) foscth) comcliecaga domeere:| Ovary small; light |.---- (Wy peosensestes Shell fairly hard.
orange yellow. |

Gagiee- dor ==: TOE oct Wanoalbosos GWecoses Ovary light pea green. .---- (ilisaaaveaseces | Soft shell. May or

may not have had
young this year.

GOR Se-dore-- 94 | Aug. 14 |.---- (10) canna |ssorcochooseaucDsoSnccoer External eggs | Fornumberof eggs, sce

| about 3 weeks table 14.
old.

(Un ee Ce 125;| Aug. 19 |--..- (WW atosas Ovary light pea-green | Clean..........--. Shell very hard.

color; very immature.

(Hl eG OE cee eet) samc bones dOjessees Ovary deep green; im- |-...- domteecess soe Soft shell.

| | mature.

72-73 |...do ....| 114,10 |-.-do ---.|----- do......| Ovaries flesh color; |---.- domeressereee Have probably molted
| | very immature. this season; never
| | mature.

ee | see) oSae TOS les il coddacsae Cy ccaded Ovary bright yellow...|-.-.- COjascece sos Do.

1 | Gest See IGF Nos aitsand osand doje see Ovaryat darlosvoreeny|ansssecccceeseeee | Shell colors bright; has
swollen, ripe, eggs probably molted this
flow out when ovary season. Degenerated
is cut; diameter of | eggs of former sexual]

| lobe, one-half inch. | percd present. Fig.
141, pl. 39. |
UG eae doce 1243) Aug. 21 |...-- Gk sccon6 Ovary light green...-. External eggs in | Hard shell. Ova light |
© gg-nauplius | (teen about nucleus.
stage. igs. 150 and 151, pl.
41.

Ll |boci® snee HS sont once ance GWsseoee Ovaryecdark er ee ny: -.s.sseee-eeereee | Hard shell. See draw-
nearly ripe; largest | ing, fig. 123, pl. 36.
ova, 1.3 mm. in diam- |
ter. |

USileeedOe se. IDL |e oeGh)ceed bonus doyecces Ovary nearly ripe-.--.. Cleaneeres==ssece! Shell moderately hard. |

loo cece TKO | iW Sced bands GW S5ocex Ovary light pea green; |---.. G1) Cosnsosedcee Shell moderately hard; |
diameter of ovum probably not mature.
about one-third that
of nature egg.

80) |e dora TOES loca waaa|boood dojeeeees Ovary light yellow. |.--..-. Comeceeninne td: | Shell moderately hard;
Ov: lobe 7mm. in di- | immature.

| ameter.

Sle ee CObere! 113 |-.-do.... Ovary light pea green. -- Soft shell.

S2iir oe C0eeee 10g |...do.-... Ovary yellow ....------ | Molted this season.

| | Immature.

GB) |e Gh) se. Ge |eeaQ® aonclancee (0 Sosseq|bcond GO poseSopaccsossaded |----- GM nesoncestese | Shell hard.

CE eoHtit) Goce TPS |B oeGt) so5c|eopee GW) penc6c Ovary yellowish, small.|..... GH) ace canesaone Probably molted this

| | season. Immature.

85 |..-do.-..) UY eect ecc4 hescd GW ssoes¢ Ovary pea green....-..|..... i) cs canescsns | Probably molted this

| year. May have had
young.

OF THE UNITED

STATES FISH COMMISSION.

TABLE 20.—General condition of the sexual organs, of the external and internal eggs, etc.—Continued.

68 BULLETIN
: Date of
No. Sex. | Length. capture.
| Inches. | 1890.
86 Female _| 11 | Aug. 21
Cy) baer aase Fh eek @ Ko) ecraey
|
S8aieedorces| 12 .-do
BOM ise Oversees iteareia| ee do
9022.0 ap ee (beets eee
| 1891
91 -do 5g | July 22
PAN eet ysl pales Oates
93 |...do 718) July 24
94 |. .do 94 | July 30 |
| |
95 |.--do. 93 | July 30
S652 0 Ol 93 | Aug. 4
97 |...do 12 | Aug. 5
98 do 215) June 30
99 |...do 2.) See one lier
100 |...de 113) July 18

Locality. -

Gay Head,
rock bot-
tom.

Harbor.

| Menemsha. -

Woods Hole
Harbor.

Menemsha. -

Condition of sexual
organs.

Condition of swim-

merets.

Ovary cream color ..-...

Ovary light green,
flecked with yellow
(degenerating eggs)

| and white (young

| _ eggs).

Ovary whitish, flecked
with yellow spots,
and dark green un-
extruded eggs.

Ovary same as in No.87-

Ovary white, 15mm. in
diameter.

Ovary whitish, with
tinge of pink, 3mm.
in diameter.

Ovary white, about
3mm. in diameter.
Ovaries nearly ripe;

seminal receptacle
| _ charged with sperm.
| Light green. Ova light
yellowishgreen. No
sperm in seminal re-
ceptacle.

Ovary nearlyripe. Fe-
male impregnated.
Ovary light pea green.

Ovary white; length 1§
in.; diameter ; in.

Female impregnated. |

External eggs
about six weeks
old, extruded
about July 10.

External eggs in
egg-nauplius
stage, laidabout
August 6.

External eggs in
late segmenta-
tion.

Remarks.

Immature.

Very hard shell. See |
drawing of ovary and |
ova, figs. 137 and 135,
plate 38.

Soft shell.

Shell fairly hard.
Do.

Hard shell.
Do.

Do.

| Hard shell. For sec-
tion of ovary, see tig.

Shell hard; to molt
soon; eggs hatched
this season. See
drawing of ovary and
ovum, figs. 188 and
133, pl. 38.

| Hard shell. See draw-
ing of ovary, fig. 132,
pl. 38.

Eggs laid about July 25.

These results, with those given in table 15, show very clearly that on the coast of
Massachusetts female lobsters become sexually mature and produce eggs for the first

time when they have attained the length of from 8 to 12 inches.

greater chance of survival.

between two successive sexual periods,

Very few lobsters
under 9 inches in length have external eggs, while only few have attained the length
of 104 inches without having them. The limits of 9 and 10 inches, which have been
variously adopted, are therefore too small, and should be increased if the lobster is to
receive the benefit which is intended by this form of legislation.
to protect the very small lobster and not to extend protection to the lobster which is
about to spawn, in view of the natural increase of the species, since the latter has the
It is highly probable that the majority of female lobsters
104 inches long are sexually mature. Itis possible that the limit is sometimes extended
at both extremes and that very rarely a lobster produces eggs before it is 8 or even 74
inches long or fails to produce them until it is over 12 inches in length. Out of over a
thousand egg-bearing lobsters which have been examined at the Woods Hole station
during the past four years there have been found only 20 lobsters measuring from 8
to 83 inches, or less than 2 per cent of the total number with external eggs.
statistics of the majority of these, see table 15.)
tions of which are tabulated above. were not, however, taken at haphazard, but were
selected in many cases to illustrate the development of the ovary and its growth

It is clearly illogical

(For
The hundred lobsters, the dissec-

_—eoo

THE AMERICAN LOBSTER. 69

Culling from table 20 all lobsters 9 inches long and upward which are immature
or have not as yet spawned, the record is as follows:

Number in table 20. | pene
Ni Cosdocodesoo paaSreBBoo sass 93;
SORE eve Pe Me cee tac oy,
CNS ate a a gis
PAT CV/iscsccounosascuauedsoas 10
FU EV ae nites tere ee tea 104
TARO Neca ge ae AI 103
ANG is Gas Hes p pO SOR SRAt tae 104
[Yi As ne ee Ree 103
EB pes eens ae 10%
BOR erica eccie Seaicntercies (Ul
(Oe ie See etn ere, 4
OP alse aaa eB nO NRR EE seb aenSee 113

Total number, 17.

The following would have laid eggs during the current season—that is, they were
within a few days or a few weeks of their first spawning:

| . i

Number in table 20. |
BYILGYT. Seba one a a reorr arse 98
96 seese conser cekeaasesee 93

Tike eae Neer ess See 102 |

D5 aes gee eer re meet asia A 104 |

(reaeretpaecr Aasnasaeaaeeteee Ta |

Dex cake noes Sey Brey ss eter iat 113
Eri eind seca nee ennai an aan 12

Total number, 8.

We thus find that 25 females, a large number out of the entire list, varying from
9° to 12 inches in length, had either never reached maturity or were mature for the
first time. Of the 17 immature females, 6 are 105 inches or upward in length, and
the ovaries in most cases would not have matured for at least two years. In order to
be on the safe side I have purposely omitted from the enumeration all doubtful cases.

It may be asked, How can you be certain that a lobster has never spawned? The
answer to this question is easily found by examining the ovary. If the surface or
interior of the ovaries or their ducts are flecked with small yellow or yellowish orange
spots, in however slight a degree (see fig. 136), it is an infallible sign that external
eges have already been carried. If these specks are examined under the microscope
(fig. 150, plate 41), it will be seen that they are the remnants of old eggs which failed of
extrusion at the last sexual period. At every such season of egg-laying there are
always, as we have already seen, a few residual eggs, out of the thousands which are
laid, which stick fast in the ovary or in its ducts, or for some cause are not driven
outside of the body. These remain in the organs and undergo degeneration in situ.
It is, perhaps, not surprising that traces of these eggs persist in the ovary for upward
of two years without being completely absorbed, when it is remembered that the semi-
fluid contents of the egg are surrounded by a tough bag of chitin, the primary egg
membrane.

Another means of determining the sexual condition of the female, which, I consider
to be also infallible, is the color of the ovaries. The ovary immediately after egg-laying

70 BULLETIN OF THE UNITED STATES FISH COMMISSION.

is always of an opaque grayish-white tint (plate 38, fig. 136). The ovary of a lobster
taken at the time of the hatching of the brood (plate 38, fig. 138), or several weeks
after it, is invariably, so far as my observation goes, of a light pea-green color, and
possesses definite histological characteristics which will be considered in another place.

The ovary of a female which is approaching maturity for the first time (see Nos. 22,
26, 47, 58, 67, 74, 83, etc., table 20), on the other hand, is variablein color. It may have
a flesh or almost salmon tint, a cream color, a dirty yellow, bright light-yellow, light
olive-green color, or one of many intermediate tints.

The interesting fact has already been pointed out that the percentage variation in
the numbers of eggs produced by lobsters from 8 to 12 inches is excessively great.
This points to the conclusion, which is confirmed by anatomical evidence, that the
period at which lobsters reach sexual maturity is a variable one, extending over
several years, over a period, at least, in which lobsters vary from 8 inches, or slightly
under, to 12 inches, or slightly over, in length.

THE FREQUENCY OF SPAWNING.

Is the lobster an annual spawner, or, to put the question in another way, what
percentage of mature female lobsters produce external eggs each year? These ques-
tions, although of much importance, have generally received erroneous answers.

In the summer of 1890 I first demonstrated, upon the ground of anatomy, that the
lobster did not and could not breed annually, as had been commonly supposed. This
is proved, first, by the growth of the ovarian eggs, and confirmed by the relatively small
percentage of females with external eggs captured during the winter and spring.

The growth of the ovarian eggs was followed from the time of hatching of the
brood until the ova of the next generation were ripe and ready for extrusion. (See
note, p. 152.) These results are embodied in table 20. In some notes published
in May, 1891, I pointed out that three-fourths of the whole number of egg-lobsters exam-
ined in the summer of 1890 in Vineyard Sound had extruded eggs during the latter
part of July (see table 7). It was also shown that the eggs which are then laid are
“carried by the female throughout the fall, winter, and spring, and are not hatched
under natural conditions until the following summer” (92). The hatching period
was given as extending over a period of about eight weeks, from May 15 to July 15.
This agrees, for the most part, with the experience of recent years.

Bumpus (30) gives correctly the periods of spawning—with the exceptions I have
noted—of incubation, and hatching of the young. Garman (72), in a report upon the
lobster to the fishery commissioner of Massachusetts, summarizes his results as follows:

(1) The female lobster lays eggs but once in two years, the laying periods being two years apart.

(2) The normal time of laying is when the water has reached its summer temperature, varying in
different seasons and places, the period extending from about the middle of June till about the Ist of
September.

(3) The eggs do not hatch before the summer following that in which they were laid, the time
of hatching varying with the temperature, and the period extending from the middle of May till
about the Ist of August.

These conclusions—subject to the corrections which I have pointed out—are essen-
tially a repetition and confirmation of facts which were already known.

Mather emphasizes (135, 136) the facts that the lobster carries its summer eggs all
winter and that it breeds once in two years.

In order to prove with certainty that the lobster can not breed every year, we
have only to dissect a female which has recently produced a brood, or has external
eggs nearly ready to hatch, in June, July, or August. In table 20 records of over

ee ae ee

THE AMERICAN LOBSTER. (3

twenty-one such dissections are given (Nos. 1, 4 to 10, 29 to 33, 35, 37, 38, 40, 53, 56,
62, 95) which illustrate the condition of the ovary before the eggs hatch, up to about
the middle of August, or from six to eight weeks after hatching. The ovarian eges
have had, in all these cases, from ten months’ to a year’s growth, this interval having
elapsed since the last sexual period, when eggs were extruded.

The colored drawing, fig. 138, plate 38, represents, in natural size, the ovary of a
lobster (No. 95, table 20) four to six weeks after the hatching of its eggs. In figs. 136,
137, and 138 I have given representations of the ovaries of the lobster as they appear
thirty-six hours, six weeks, and one year after egg-laying. Figs. 134, 135, and 133
show the average size and form of the ovarian eggs, drawn to the same scale, at these
various periods. The ovarian eggs are in about the same condition of immaturity in
figs. 133 and 135, and it would seem that immediately after egg-laying the ovary grows
very rapidly, and then enters upon a long period of rest. In the following summer,
when the external eggs have hatched, another period of rapid growth is experienced
in the ovary, and at the beginning of the third summer after ovulation there is a third
period of active growth which continues until the new ova of the next generation are
ripe. That the spawning periods are thus two years apart is a valid inference drawn
from the study of the anatomy of the reproductive organs. (See note, p. 152, and in
particular the description of fig. 138, p. 246.)

If the spawning period of the lobster is a biennial one, and if the sexes are equally
divided, we should expect to find half of the adult females carrying eggs each year.
In other words, one in every four mature lobsters (of both sexes) captured would carry
external eggs. Since lobsters do not mature at a uniform period, or when of a uniform
size, it is impossible to get perfectly accurate data upon this point. It would be
impossible, furthermore, to trust any data, unless we could be certain that the egg-
bearing lobsters were uniformly distributed. The facts which we have, relating to
this point, are however, worth considering.

In April, 1889, a number of lobster pots were set in the harbor of Woods Hole
by Vinal N. Edwards, and a daily record of the catch was made. A total of 3,230
lobsters were captured, as described in table 21. About one in every seven bore eggs.
The percentage of females with external eggs to the whole number of females taken was
40 in April, while it dropped to 36in May. This slight fall might or might not be owing
to the hatching of some of the eggs, while it is evident that the drop to 9 per cent in
June is due to this cause, by far the larger part of the eggs being hatched in this month.

It is seen that in the total catch of 2,657 lobsters, from December 1, 1893, to
June 30, 1894, the sexes are very nearly equally divided, and that about one in every
fifteen lobsters captured bore external eggs. Neither this nor the percentage of
females with eggs to the whole number of females has any special significance, since
both mature and immature are included. Striking out the months of May and June,
when the eggs are mostly hatched, and eliminating the smaller lobsters, we find the
percentage of egg-bearing lobsters 10 inches long or over to the whole number of
females of the same length with or without eggs (that is, mature female lobsters), to be
21.79. If the limit is taken at 9 inches, we find the percentage to be 19.81. In other
words, about one-fifth of the females 9 inches or more in length bore eggs.

The catch off No Man’s Land in May, 1894 (table 1), illustrates very well how
the conditions are affected by the locality. Out of 1,318 lobsters taken 93.5 per cent
were females, and 63.7 per cent carried eggs; moreover, 68 per cent of the total number
of females bore eggs.

72 BULLETIN OF THE UNITED STATES FISH COMMISSION.

TABLE 21.—Percentage of male to female lobsters and the percentage of egg-bearing females taken in
Woods Hole Harbor.

| Time of capture.
a —— | For
eee 4| 1889, | 1889, | 1893, | 1894, | 1894, | 1894, | 1904, | 1894, | 1894, | whole
to 30, | May. June.| Dec. | Jan. Feb. |March.|April.| May. | June. | P® :
| \
Notalcatchease see saectee creo eee | 104} 912 | 2,184 | 204 501 246 348 457 434 447 5, 887
Wasa emma ae nee ee ae cca. 49 | 440 | 1,009 123 250 | 116 161 247 197 219 2,811
em alesse acca serene ccne ee eee SD aller o02a eh p 101 251 130 187 210 237 228 3, O76
Males under 10 inches. --..-. SeeKesc ee Bescicts Hoesen Saasere sServoud bodedaad accase Bp Rose eo pecenoae eacaasce 49
Malesmunderl0sinchess22-- 2: 22-|secieces 418 976 97 215 107 137 210 173 196 | 2,529
Males over 104 inches tts meee st eee 22 | 33 26 35 9 24 37 24 23 233
Females under 10 inches ......... Gil eeeisace leeeenee |deeesee RORSS eae ReneS eee Bere pase aeaceas| heatssad bocoqcos 55
Females under 104 inches ........|........ 439 | 1,099 | 78 | 194 106 147 163 207 192 | 2,625
Females over 104 inches. ........- [eae erie 63 | 76 23 | 57 24 40 47 30 36 396
Females with eggs ..-..---..----- 22 185 | 108 | 22 36 11 | 12 33 | 34 20 483
| Females without eggs | 3 |
Females under 10 inches with
OPTS sa cc coc csee oe see eee eaten |
Females under 10% ine
| _, &8ss -
| Females over 10
OPES eeessesaee eee oe seer er Ja-eeee-- 54 OS | eaoces |S nroidntere lerjere nics [ome oe arene bennett
| Percentage of females with eggs |
to tote aT; number of females.----- 40 36 9 | 21.78 14. 34 8.46 6.42) | 15.71 14, 35 8.77 17.48

Percentage of females with eggs
to whole catch
Percentage of females to males---

bo
—

5
8 4.47 3.45 | 7. 22 7. 83 4.47 8. 99
5. 02

1956} 4.9'| 9.82 i
2.1 120.30 | 104.11 | 106.30

| 112.2 | 114.3 | 116.4 | 82.

The inspector of fisheries for the Province of Prince Edward Island says:

In 1879 returns from almost all the factories then in operation gave, for the whole catch, only
from 3 to 10 per cent in spawn, much the larger portion being in July.

This agrees closely with the results obtained at Woods Hole, but it does not
follow, as Mr. Duvar supposes, “that one-fifth of the females carry ova each year,”
or that “there are four times as many young breeders coming forward as there are
egg-bearers,” and ‘that one-fourth of the number come into breeding year after
year” (209, p. 234), since the adult lobster does not breed annually, as he erroneously
supposes.

From December 1, 1893, to May 1, 1894, 358 female lobsters measuring 10 inches
or more in length were taken in the harbor of Woods Hole, and 1,234 were captured
during the same period at No Man’s Land, in all 1,592 lobsters, 57 per cent of which
bore external eggs. If we include the 9-inch lobsters, we find that the total number
of females taken at both places is 1,779, and that 53 per cent carried eggs. This
supports the conclusion already reached from the study of anatomy, that the lobster
breeds once in two years, in which case 50 per cent, or fully one-half, of all sexually
mature female lobsters spawn in some part of each year. It also shows very forcibly
that valid inferences respecting the breeding habits can not be drawn from observa-
tions made in a restricted area. Thus, had our attention been confined to Woods
Hole it would have appeared that only one-fifth of adult females bore eggs (from
Deceinber to May), or that the lobster spawned only once in five years. !

Dmtrenpaui (61) Ramil that only 25. 4 per “aah of ee gueeasoal to be of adult age een at
Heligoland carry eggs, and hence concluded that the European lobster becomes productive only once
in four years. Besides the objection that the data are derived from one locality, which, as table 21
shows, is a serious one, there is the further difficulty that over 10 per cent of these female lobsters
were captured during the months of July, August, and September, when, according to Ehrenbaum,
both the laying and the hatching of the eggs occur. This alone might vitiate the result. The best
way to test this question by experiment would be to take a female which had recently hatched a brood
and keep her alive until the following summer, when the next batch of eggs would be due, in case the
spawning period is a biennial one. So far as I know, this has never been done.

THE AMERICAN LOBSTER. 73

It should be borne in mind that, as we have already seen, a certain number of
lobsters from 9 to 12 inches long have never borne eggs. Thus the chances for error
in making estimates of this kind are further increased.

The percentages given in table 21 must therefore be greatly increased to express
the ratio between the actual spawners of the current year and those which have
reached the spawning age, since in the total number of females there were undoubtedly
included many which were not mature. While the percentage of egg-lobsters taken
in the same locality may vary considerably from year to year or from month to month
it seems probable that if we could average the results taken from many different
localities along the coast we should find that the number of spawners each year
represents about half the total number of mature females.

RELATIVE ABUNDANCE OF THE SEXES.

Some species of crustacea are strictly monogamous, such as the beautiful tropical
shrimp, Stenopus hispidus, which is always seen swimming in pairs, the male and
female being rarely separated. This is also true of another delicate shrimp, Pontonia
domestica, which lives in the mantle chamber of the mollusk Pinna. In such cases the
sexes are of necessity about equally divided. But in the lobster there seems to be
no attachment of this kind. It is probable that a given male fecundates more than
one female, and it is certain that the sexes are distributed with great irregularity, at
certain seasons of the year at least, as I shall presently show. Nevertheless, if an
extended census could be taken, at different points on the coast, it is very probable
that but little difference would be found in the numbers of the sexes.

The following table shows the relative abundance of male and female lobsters
found in Woods Hole Harbor and at No Man’s Land:

TABLE 22.—Relative abundance of male and female lobsters at Woods Hole and No Man’s Land.

r | Per cent
Date. | Total | Male. | Female. | of females |
catch. | | to males
Woods Hole: |
IED, “gyal PER) cp odbdacsoppopenucd 104 | 49 55 | 112. 2
Nib yl disesaaconctdahoesceremonce 942 | 440 502 | 114.3
AIO Ti Setar Ses eac me peeerie eric 2, 184 1, 009 1, 175 | 116.6
IEGE, WYSWANNS Posoccoe node oseeoenene 224 123 101 | 82.1
1SGA ANNUAL Y tesa fesse emcee ee 501 | 250 251 100. 4
Mebruaryereescesesen ssc soeae 246 116 130 | 112, 07
Marchetti ccna nerease eae | 348 | 161 187 | 116. 15
Wri Peete eee eae nce 457 247 210 | 85. 02
WEA osoase SAnaneaononUuBnEsanbe 434 197 237 120. 30
CuO daccecepeuomccsenbeoosee 447 219 228 104.11
Lotals\eosencsssscesees eer | 5, 887 | 2, 811 3, 076 106.30 |
No Man’s Land: |
TE WER ye sacae. cophSUHESEASSSAOOoe 1, 318 84 1, 234 1, 469

In the monthly catches at Woods Hole in 1889 the females preponderated by 12 to
16 per cent, while in the total catch for 1893-1894 the sexes are very nearly evenly
divided. During this period the percentage of females to males fluctuated from 82.1
minus to 120.30 plus, a variation of about 38 per cent. The traps were stationary,
but the lobsters were constantly moving about over the bottom; yet there was no
segregation of the sexes, and such variation as we find in the monthly catches has no
special significance.

74 BULLETIN OF THE UNITED STATES FISH COMMISSION.

When, however, we glance at the data from No Man’s Land, it is evident that
something besides chance has caused the overwhelming preponderance of females,
1,469 per cent. It seems almost certain that this condition of things is only tempo-
rary, and it may be explained, as I have suggested in another place (see pp. 23,24), in
relation with the inshore migration and the hatching of the eggs.

Regarding the relative abundance of the sexes of the lobster, Verrill (196) remarks:

Among those which I have examined from New London, Waterford, and Stonington, Connecticut,
in our markets, I have not noticed any marked inequality in the number of the sexes. Mr. Smith
examined the lobsters in the market at Provincetown on two occasions, in August and September,
without finding any decided differences in the number of males and females. He also repeatedly
examined those in the fish-markets at Eastport, Maine, in summer, with the same result.

Capt. N. E. Atwood published in 1866 a paper on the habits of the Jobster in
the proceedings of the Boston Society of Natural History (5), in which he makes
the following remarks:

From Plymouth northward and eastward [lobsters] are caught in deep water in the months of Feb-
ruary and March, but not in large quantities; as the season advances they come near the shore and
remain through the spring, summer, and autumn, and are very plentiful. Along this range of coast
three-quarters at least are males at all seasons of the year. At Cape Cod (Provincetown) their habits
differ very much from the habits of the lobsters on the north shore. They do not come there until
June and remain until October, when they disappear and go to parts unknown. One very singular
fact I have noticed is, that the lobsters which visit Cape Cod are nearly all females; they appear to
come near the shore for the purpose of depositing their young, after which they pass away and others
in turn take their places, as is indicated by the change that is constantly taking place, for when the
fishermen are catching great quantities of large, good hard-shelled lobsters—and they are unusually
abundant—perhaps the next day there will be a new kind, smaller and not of so good quality, the
former ones having passed away and others come to take their places.

In Boston the number of lobsters sold annually can not be much short of a million. The
male lobster is preferred and is the most salable, as this city has always been supplied from the
northern shore of Massachusetts and coast of Maine, where the males are most plentiful. It is a great
advantage to the fishermen that the people prefer males. In New York it is very different in this
particular, the city being supplied from Cape Cod after June, and the female lobsters thus considered
much the best. I have sold many lobsters in New York, and males sell at only about half price. The
male is much poorer than the female in meat.

I have quoted the foregoing passages at some length, not because they are free
from error, but because they were written by an intelligent fisherman at a time when
scarcely anything was known of the habits and general biology of the American lobster.
If such a preponderance of females actually occurred on the shores of Cape Cod it may
have been a seasonal phenomenon, similar to that observed at No Man’s Land. It
did not exist in August and September, when the observations of Professor Smith
were made at a later period.

The statement that males are more plentiful than females on the northern shore
of Massachusetts and the coast of Maine is without doubt an unsupported generali-
zation. Conflicting statements in regard to this subject are often given by fishermen,
who, as Verrill suggests, probably do not often discriminate the sexes when the females
are without eggs. The only detailed facts which we possess on this subject are those
recorded in tables 21 and 22, and they seem to point to the conclusions already drawn.

Chapter I1].—MOLTING AND GROWTH.

EARLIER OBSERVATIONS.

The process of molting, which makes growth possible to the arthropod, is of such
interest and importance that it deserves very careful attention. There is much to be
added to our knowledge of this subject in the lobster, and I shall deal with it at
full length. Aristotle knew very well that crabs and lobsters shed their shells (The
History of Animals, Book viii, c. Xtx), although his observations were not accurate ;
but the fact was forgotten and finally denied altogether.

It is only necessary to go back to the beginning of the last century (in 1712) to
find Réaumur (167) demonstrating that the river crayfish periodically cast its shell,
yet in the early part of the seventeenth century, a hundred years before, Olaus
Wormius, according to Couch (47), speaks of the molting of crabs as a thing not to
be doubted.

The regeneration of the lining of the stomach of the crayfish was reported by
Van Helmont, but this writer’s reputation did not lend much weight to the statement
until it was confirmed in 1709 by Geoffroy (74).

To that marvelously acute observer, Réaumur, we are indebted for the best account
of the exuviation of the crayfish. He took crayfishes which appeared to be ready to
molt and placed them in jars of water in his museum and watched them carefully.
Others he put into boxes, the bottoms of which were pierced with holes, and moored
them in the river Marne, which flowed past his garden. The crayfishes in the river
were under more favorable conditions than those kept in the house, and molted more
frequently in consequence. He gives a very circumstantial account of the external
process of molting in the crayfish, which took place in June, July, and August. The
time occupied in the final act of casting the shell by crayfishes kept in the river was
from seven to fifteen minutes, while those in the house often struggled for several
hours before they were free. Sometimes they died in the operation, especially the
young ones. Some would lie on their sides, some on their bellies or backs, and in the
latter case he observed that they frequently died.

However, as Couch remarked, Réaumur’s paper produced so little effect that
when, many years later (1756), Peter Collinson communicated some cursory remarks
on this subject to the Royal Society, his account of the molting of the crab was received
with so much doubt that his second paper was chiefly employed in furnishing evidence
of the fact.

Observations on the molting of the higher crustacea have since been made by
Couch (45, 46, 47), Gosse (81), Chantran (37), Max Braun (22), Vitzou (197), Sars (176),
Hyatt (104), Brook (26), and others. The histological changes involved in the molting

75

76 BULLETIN OF THE UNITED STATES FISH COMMISSION.

process have been studied by Max Braun (22), and more recently by Vitzou (197). As
so often happens, there are many observations on this subject which either ignore the
earlier and often better ones, or add nothing of value to our knowledge of the process.
Hyatt, in remarking that, while the molting of the lobster had been previously de-
scribed several times, ‘‘no professional naturalist” had ‘actually seen the process and
recorded his observations,” appears to have overlooked the account of Sars (176), which,
however, is not particularly circumstantial.

Sars saw a lobster in the act of molting in July near Tananger, in Norway. He
Says:

It had just been taken out of a lobster box, and could be handled without its offering the slight-
estresistance. The shell on its back was burst in the middle, and the tail and the feet were nearly out of

the old shell, while the largest claw stuck out only half its length. This latter portion of the change is
evidently very dangerous, and, although I observed it for quite a while, I could see little or no progress.

This lobster was not a good exponent of the molting process. As soon as the
larger claws begin to be withdrawn from the old shell the exuviation, under normal
conditions, is speedily brought toaclose. Nor isit true that the lobster “only reaches
its former size after a considerable time has elapsed.” According to Sars, the lobster
on the Norwegian coast molts chiefly in July.

Both Couch (45) and Salter (174) have given accounts, at secondhand, of the
molting of the European lobster. Couch, writing in 1837, says that the newly molted
lobster shows great activity in effecting its escape, which is undoubtedly true in some
cases, but not in all. The lobster whose cast shell is described escaped “through an
aperture too narrow to have allowed it to pass if its new covering had possessed a
very moderate degree of firmness.” He supposed that escape was effected by the
cracking open of the shell, in the middle line, where he noticed that in life a faint
stripe was perceptible. He observed in a lobster preparing to molt that absorption
took place along this area, and inferred that the two halves of the shell were com-
pletely separated when the critical moment came. Of the molting, he further says that
“it is not improbable that the general opinion is correct which limits the exuviation of
the adult animals to once in the year,” and “ general opinion” does not seem to have
made much progress in clearing up this matter during the last fifty years.

Salter’s account, published in 1860, is interesting on account of some extraordi-
nary statements, such as that in molting the legs are extracted pair by pair, which of
course is a physical impossibility, as Hyatt pointed out, and that the abdomen is the
part first withdrawn from the old shell. This latter statement expresses exactly the
reverse of what has since been found to occur.

Wheildon (202) published in 1875 a short paper containing some interesting facts
on the molting habits of the American lobster, which will be referred to again.

The work of Vitzou, which appeared in 1882, is the best yet done on this subject.
He treats of the histology of the oid and new shell, and of the organic and “inorganic
reserves,” which are supposed to be laid down in certain tissues with reference to the
molting period.

Hyatt’s paper (104), appearing in 1883, gave an accurate account of some of the
phenomena of exuviation in this species.

Packard in 1886 published some notes (147) in which very little is added to our
knowledge of the subject. He says that “the integument of the legs is molted last,
and when, owing to rough handling, the process is delayed, the extremities of thelegs

Bull,.U. S.F, C. 1895. The American Lobster, (To face page 77. ) Plate A.
=

Cur 4.—Part of transverse section of exopodite of pleopod
of female lobster (the cuticle removed), showing the dis-
tribution of the cement glands. July 19, 1891.

Bl. S, blood sinus. ep, chitinogenous epithelium. 7”. G,
tegumental gland.

Cur 5,.—Diagram of vertical section through skin, showing ategumental gland (relatively much smaller than represented)
in section and its duct opening to the exterior, also hair pores perforating the cuticle, with the superimposed hairs or sete.
The structure of the cuticle or shell is diagrammatically shown.

B.S, blood sinus. cap, capsule of tegumental gland. D,dermis. d,ductof gland. d!,mouth of duct. ep, chitinogenous
epithelium. Gd. C, gland cell. H.p, hair pore. Mu, muscle. N, nerve,supplying gland. SC, central nerve cell. s', plumose
hair. s,simple hair. 1,enamellayer of shell. 2, calcified pigmental layer of shell. 3, calcified non-pigmented layer. 4, inner

non-calcified layer of shell.

Drawn by F. H. Herrick.

THE AMERICAN LOBSTER. fre

slough off.” The remarkable statement that ‘the abdominal legs are molted before
the thoracic ones” would imply that the hinder part of the body is first withdrawn
from the old shell, which is not true.

The statement that the lobster ‘“‘vemains inactive for nearly or quite a week, until
the new crust becomes hard,” can not be accepted without modification, since the soft
lobster is frequently caught in traps, and the newly molted lobster often displays
surprising agility, and besides it requires more than one week for the shell to become
hard.

Brook (26), writing in 1887 on the reproduction of the lost parts of the lobster,
has some interesting notes on the growth of the European lobster which he kept and
observed in an aquarium for nearly a year and a half in one instance, during which
period the animal molted four times. The ecdysis usually occurred at night, and the
exuvium was buried.

No one, strange to say, has ever examined the cast-off shell and observed with
sufficient care the areas of absorption. This has resulted in much useless discussion
as to whether the carapace splits along the middle line when it is cast off. I shall
refer to this hereafter.

We are now concerned with the adult animal oniy. The molting of the embryo
and larva will be considered in Chapter X11.

THE STRUCTURE AND GROWTH OF THE SHELL.

The phenomenaof the molt are unintelligible without a knowledge of the struc-
ture of the skin or integument. The histology of the shell in the crustacea has been
studied with varying degrees of suecess by a number of naturalists—by Carpenter (34),
Lavalle (176), Williamson (205), and Tuliberg (1914). The most accurate statement is in
the paper by Vitzou (197), on which I shall mainly rely in giving the following account.

The skin as a whole is composed of dermis and epidermis, and consists of the
various parts shown ‘n the diagram (cut 5). The epidermis is made up of a single
layer of chitinogenous epithelial cells, and of the shell which they secrete; the dermis
is composed of connective tissue, blood vessels, nerves, pigment cells, and glands,
The shell consists of four layers, namely: (1) the thin outermost layer, which I shall
eall the enamel layer, apparently structureless; (2) the pigment layer, composed of
parallel lamelle, traversed by canaliculi and filled with pigment and lime salts; (3)
the calcified layer, devoid of pigment but otherwise like the last, forming the greater
part of the carapace; (4) a noncaleified inner layer, composed of very thin lamellie.

The chitinogenous epithelium corresponds to the Malpighian layer of the epi-
dermis of the vertebrate, while the layers of chitin represent its horny cuticle.

The vertical canaliculi correspond, as Vitzou has shown, in certain decapods,
to the boundaries of the chitinogenous 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 undergo a
great change. They grow out, vertical to the surface, into very slender and exceedingly
long rods. (Compare Cut 11, and figs. 171, 173, plate 43.) The epithelium formed
over the surface of a budding limb is of the same character. The chitinous layers of
the new shell are formed by discontinuous thickenings of what, according to Vitzou,
may be regarded as the upper wall of the epithelial cell. Thus are formed parallel
lamelle of varying density, which fuse with those of adjoining cells and make a contin-
uous shelly crust, :

78 BULLETIN OF THE UNITED STATES FISH COMMISSION.

At the time the shell is ready to be cast the tegumentary covering consists 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.

The connective-tissue cells are now of large size and contain granules of glycogen.
Claude Bernard first demonstrated the presence of glycogen below the carapace in
crustacea. Glycogen was extracted by Vitzou from the connective tissue, liver,
lymph, and ovaries, during the molting period. Besides acting as a pancreas, the
liver was found to be a great producer of glycogen during the molt. Glycogen is
thus an organic reserve, which furnishes material for the growth of the new shell and
tissues. According to Vitzou, Schmidt and Berthelot have shown that the chitin of
the crustacea contains a principle belonging to the same group as cellulose and lignin.
This substance, under the influence of sulphuric acid, may be transformed into a body
analogous to glucose. Hence the remark of Claude Bernard, that “‘ without forcing
the metaphor one may say that the crustavea are enveloped in a carapace ef wood.”
(Lecons sur les phénomenes de la vie, 1879. t. 2, p. 113.—197.)

The enamel is plainly the first product of the secretions of the skin which goes into
the new shell, and when once laid down can not be competely removed except by a
molt. The enamel is often partially removed by friction, as is seen in the abrasions
on the shells of old lobsters or those about to molt.

The surface of the shell, particularly that of the carapace, has a decided punctate
appearance, due to the hair pores. These mark the points where set either pene-
trate the shell now or did so at an earlier stage of development. In the adult lobster
the setie of the carapace have disappeared or are worn down except upon its margins
and in the orbital regions. In the fourth larva, however, the whole carapace is seen
to be studded with hairs (fig. 113, 115, plate 35).

If the carapace—better one without pigment—is examined with a hand lens, the
surface is seen to have a beautiful though somewhat irregular mosaic appearance.
It is divided into polygonal areas which inclose the hair pores. These markings are
probably due, as Professor Patten has shown to be the case in Limulus, to shallow
depressions in the enamel, dependent upon a peculiar bending together or clustering
of the outer ends of the canaliculi. The hair pores open on the inner side of the
shell in small blister-like elevations.

A very minute pore of another character is scattered among the hair pores on the
inner side of the shell. It has the appearance of a symmetrical crater with a minute
tube issuing from it. This is the duct and opening of the tegumental gland. The
distribution of these two kinds of pores would probably repay careful study. But
few parts of the carapace, such as the white tendon marks (see p. 135), are wholly
free from them. Toward the lateral margins of the carapace they become exceedingly
small and numerous. Some of the superficial pits in the dorsal region, on the other
hand, are very large.

We thus see that the dense shell is 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. The bearing of these facts will be better appre-
ciated when we discuss hereafter the function of the tegumental glands themselves.

THE AMERICAN LOBSTER. 1S)

THE SHEDDING OF THE SHELL IN THE LOBSTER.
THE MOLTING PERIOD.

The hard-shell lobster is heaviest, has the firmest flesh, is hardiest, standing
transportation best, and therefore most valuable for the market. A large percentage
of all lobsters taken during the fall and winter months are of this character, and all
or nearly all lobsters caught in March, April, and May belong also to this class.
Shedders and soft-shell lobsters are ‘aan in greater or less abundance from June to
October, varying somewhat with the season and locality and surrounding conditions,
such as the nature of the sea bottom and the temperature of the water. By far the
ereater number of lobsters in all seasons, and in all places, cast their shells during the
months of July, August, and September. However, the time of shedding varies con-
siderably on different parts of the coast, being from four to six 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 in constant danger of attack from its companions, and is
easily wounded and killed. Lobsters with very soft shells and those which have been
mutilated are often kept in the lobster preserves or pounds until the shell is hardened
or the injury repaired.

No systematic data have hitherto been gathered at any point along our coast upon
the molting habits of the lobster. I am therefore glad to be able to give the results of
a series of daily observations made at Woods Hole, Massachusetts, during the apace
of seven months, from December 1 to June 30, 1894. During this interval 2,657
lobsters were captured in traps set at fixed points in the harbor. As shown in table
23,' there was no month in which either shedders or soft lobsters were not caught.

TABLE 23.—The molting of the lobster.

No. of Shell hard | Shellhard |
Tempera days for (CEiee and bright. and dull. Shell soft.
| which : ee
Wonthee ture of DSN Nature of
water in tempera- bottom.
harbor. ture is Male.|} Fem. | Total.| Male. Fem. | Male.| Fem. | Male.| Fem.
given. |
F |
December ...| 37.71 14 Rocky..-.| 123] 101] 224] 117] 101 2 0 4 0
January ----- 35. 48 27 coo dt Weupad 250 251 501 | 239 250 7 0 4} 1
February ---. 32. 54 24 Sock meet 116 130 246 115; 130 0 0 1 0
Marchieese= ==} 37. 40 27 Sood sear 161 187 348 154 186 7 0 | 0 aL
Aprilleese n= | 42.52 25 Boee dOveman= 247 210 457! 232) 206 | 14 4 | 1 0
WlGay sosesene 53. 65 26 wee dore ey. 197| 237| 434| 194] 236 3 | 1 0 0
Dunes esses | 62.20 25 al Seed oeese: 219) 228] 447) 185) 202 0 2 34 24

Only one soft-shell lobster was taken in February out of a total catch of 246, and
no “*shedders” (shell hard and dull) were captured during this month. Jeet one
soft-shell lobster only was observed in March and April, and none in May. In June,

1 Lobsters with shells ‘“‘hard and dull” are nearing the molting period; those with ‘‘soft shells”
have recently shed, and in those with ‘‘hard and bright” shells the molting time is most distant,
See p. 82.

80 BULLETIN OF THE UNITED STATES FISH COMMISSION.

on the other hand, the number of lobsters which have recently shed jumps suddenly
to 58. These observations may be summed up for the whole period as follows:

Shell Shell

| Total catch. Total. |

|
hard and
[scotia saute |
| TL S13malesesseassccee | 33 44 77 |
2, 657 |
1344 femalesaaeescese ii 26 33
|

Of the entire catch, 110 have either recently molted or are preparing to molt; 77
of them are males, 33 females. The total number of males is smaller, yet the number
of soft shells among them is 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 (see p.34), or that they molt more frequently
during those months. It is interesting to recall in this connection the observation of
Chantran (37) that the male crayfish molts twice in the year, while the female molts
but once. Females molt, as a rule, shortly after the young are hatched, and very
rarely just before the eggs are laid (see p. 35).

When I was in Portland, Maine, on the 24th of August, 1893, soft-shelled lobsters
were being caught in that region, while fishing smacks were bringing hard-shelled
lobsters from Jonesport, near the eastern border of the State. Soft-shelled lobsters
are still taken in the Portland district, as I was informed by Mr. N. F. Trefethen, for
four or five weeks before they are received in large numbers from Jonesport.

Mr. F. W. Collins, of Rockland, thinks that Jobsters shed earlier in the shoal mud
coves, which are full of eelgrass, than on rocky bottoms. The shedding commonly
occurs there on muddy bottoms in the latter part of July and the first part of August.

Shedders in small numbers are occasionally taken in Rockland in January and
February, and sometimes shed in cars at this time. In deep water outside, as at Seal
Island, Matinicus, Green, and Ragged islands, where lobsters are caught in winter in
40 to 50 fathoms, and in shoal places in summer in 3 to 10 fathoms, very few soft-shell
lobsters or shedders were taken in the summer of 1893, up to the 26th of August, not
more than a dozen among thousands examined each week. The majority of the soft-
shell lobsters from these localities come later in the season, from the last of September
to the middle of October.

Mr. A. P. Greenleaf said he had rarely seen soft-shell lobsters at Southport, Maine,
but that in the winter of 1893 (in January and February) he had taken dozens of them.

At West Jonesport, Maine, on September 4, 1893, I was told by a fisherman at
Beal Island that hard-shell lobsters had prevailed up to that time, but that soft-shells
were becoming common. He thought that the shedding was rather later than usual.
This confirms the reports made at Rockland and Portland.

Molting lobsters were very common at Woods Hole in October and November,
1890, particularly in the latter month, when Mr. Vinal N. Edwards says that more were
caught than during the earlier part of the season. In December, 1891, Mr. Edwards
found lobsters in all stages of shedding, some that appeared as if they would be ready
to molt in a few weeks, and others as if they might shed in a few days. Thus it was
probable that the lobsters continued to molt to some extent in winter, which is shown
by table 23 to be the case.

The abundance of shedders which was noticed in the late fall of 1890 at Woods
Hole has not since been observed, and it seems clear that there is considerable varia-
tion in the molting of lobsters in a single locality at this season of the year.

THE AMERICAN LOBSTER. 81

It is stated in the annual report of the inspector of fisheries of Prince Edward
Island (209, p. 236) for 1880 that soft-shell lobsters ‘‘ are seldom seen on the north side
of the island, while on the south side almost all that are caught in the month of July
are soft and unfit for canning.” A canner in Queens County says that scarcely a
lobster can be caught before the 20th of May. Soft-shell lobsters begin to abound by
the Istof August and continue abundant during this month. One-third of the lobsters
caught during August are said to be soft-shelled. The fishery officer for Cape Breton
states in his report for 1888 (270) that no soft-shell lobsters were captured during the
fishing season which closed July 28.

THE MOL'TING PROCESS.

Next to reproducing its kind, the act of molting is the most important in the life
of this animal. The whole body is covered, as we have seen, by a chitinous shell, in
which salts of lime are deposited, giving to parts of it the hardness of stone. Molting
consists of two distinct phenomena: (1) the formation ofa 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 skin below it, and when it is outgrown it must be
cast off and replaced by a new and larger shell. The new shell is gradually excreted
under the old one, and when the latter is discarded the new shell is soft and flexible
and is easily distended to meet the requirements of growth. The growth of the lobster,
and of every arthropod, thus apparently takes place, from infancy to old age, 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 increase in size, and the gradual hardening of the
shell newly formed. Not only is the external skeleton cast off in the molt and the
linings of the masticatory stomach, the cesophagus and intestine, but also the internal
skeleton, which consists for the most part of a complicated linkwork of hard tendons.
This is rendered possible from the fact that these structures ave derived from infolded
portions of the skin, and in molting they are simply drawn out of their original folds
or pockets. It is thus easy to see why the molting process is critical.

The frequency of the molting period depends directly upon the physiological
condition of the animal, which varies with its environment. The molting process is
both an expensive and dangerous operation, and calls for a considerable excess of
energy. Since it is largely 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, though but rarely in the spring. Warmer weather, a
more active life, and a more vigorous appetite, which are characteristic of the lobster
during the warmest part of the year, are most favorable, as we have seen, to the
renewal of the shell. The lobster, though a carnivorous and voracious 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.

The growth of the crustacean takes place during the period of the molt, while the
new Shell is being formed, and not immediately after the ecdysis, as is commonly
believed. It was clearly shown by Vitzou that the old shell is gradually thrown off
in consequence of the growth during the molting period, when the animal tends to
become larger than its envelope. The rapid swelling out of the body after the old
Shell is gotten rid of is due to the absorption of water through the new shell into the

blood and tissues, not to cellular growth.
F. C. B. 1895—6

82 BULLETIN OF THE UNITED STATES FISH COMMISSION.

Before the molt takes place the lobster has been for a long time preparing for it,
while growth has been going on. After molting, it is several weeks before the new
shell is as hard as the old one, so that the lobster is, for a large part of its life, either
preparing for a molt or recovering from one. It is therefore not remarkable that
lobsters have acquired many popular names among fishermen, such as “hard shell” or
“old shell” lobster; ‘‘shedder,” ‘‘black shell,” or ‘ crack back” (lobsters preparing to
molt); “soft shell,” “new shell,” “shadow,” ‘‘rubber shell,” “paper shell,” ‘buckle
shell” lobster, etc. (lobsters which have recently molted).

HABITS OF MOLTING LOBSTERS.

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
membranes at the joints, where the flesh is now seen through the old and new cuticle.
The lobster is now naturally sluggish, though not too inactive to enter a trap. When in
this condition they very commonly haunt shallow water with a sandy, muddy, or weedy
bottom, and at low tide have been taken out of bunches of eelgrass in a few inches of
water. When in this condition they frequently dig a shallow hole in the mud under
stones, where they can await the coming change with greater security from enemies.
Fishermen frequently see a shed shell lying on the bottom and a soft lobster close by
under a rock or bunch of kelp.

Jt is well known that many prawns habitually molt in the early morning while it
is yet dark. The lobster when kept in an aquarium molts either by day or night, and
it probably does the same in nature. In those which Brook observed (26) the shells
were cast off in the night and partially buried.

Shedders and soft lobsters used to be a favorite bait with fishermen who knew
where to look for them and could then find them in abundance. The shell of the black
lobster was peeled off, and the soft, pulpy flesh formed a tempting bait which fish
found difficult to resist. Mr. Vinal N. Edwards says that in 1869 or 1870 he used to
take molting lobsters for bait at Menemsha, in Vineyard Sound, in October, sometimes
a barrel of them at atime. He says that he never found a molting lobster buried in
the sand, but they were usually under bunches of seaweed, such as the common kelp
(Fucus vesiculosus) with their bodies only partially surrounded by the sand, and in 5 to
9 feet of water. It was not uncommon formerly to catch shedders in fyke nets, but he
has taken none in recent years. He used to take them occasionally with hook and line.
The lobster probably requires greater freedom in getting free from its old shell than
could be found in the most carefully constructed burrow.

While at the Vinal Haven Islands, August 26, 1893, I saw in the pound at that place
a number of soft lobsters which had molted but a few hours before. One was found
lying in the eelgrass; another, a male, was exposed on the mud bottom in 2 feet of
water. A shedder, weighing upward of 10 pounds, was caught by Mr. M. B. Spinney
in Seal Cove, Small Point, Maine, in the month of August, in very shallow water; and
in Sagadahoc Bay, near the mouth of the Kennebec River, a large soft lobster was once
found and close beside it its cast-off shell. The lobster lay buried under roots of
eelgrass and was out of water, when discovered, at low tide.

In the Peabody Academy of Science, at Salem, Massachusetts, there is a crushing-
claw of a lobster said to have come from Gloucester and to have weighed 39 pounds.
An outline drawing of this claw is given in plate 15 (see p.115). This lobster probably

THE AMERICAN LOBSTER. 83

weighed not over 25 pounds. The shell of the last three joints of the claw-bearing
limb (the parts represented in fig. 20), weighed 163 ounces. It has the thickness of
thin pasteboard, excepting at the tips of the claw, where it is denser, and probably
belonged to a lobster which had molted within three months of the time of its capture.

Putnam (754) records some interesting facts in regard to the molting habits of the
blind crayfish, Cambarus pellucidus, and of the eyed crayfish, Cambarus bartonii, cap-
tured in Mammoth Cave November 13. The blind species was of a milk white color.
One molted on January 29 and a second time April 20. Another specimen of this
species, exposed to the light over nine months, had eaten little and molted once. One
of the specimens of C. bartoniit molted about February 20, and when observed was
eating its own shell. It had devoured about half of it. This habit of eating the remains
of the old shell is very interesting, and is undoubtedly induced by the need of lime.
It was noticed in the crayfish by Baker (7) over a hundred years ago, but it is so
seldom recorded that it would hardly seem to be a fixed habit. It is probably
occasionally practiced by the lobster and all the higher crustacea, especially when in
confinement. Warrington (199) estimated that the molting period of prawns (Palemon
serratus), which he kept in aquaria, varied from twelve to twenty-four days, depending
upon food, the temperature, and other conditions. When the cast skins were not
removed the prawns devoured all the soft parts. Young lobsters, immediately after
molting, fill their stomachs with any calcareous inatter at hand, such as the fragments
of the shells of mollusks and crustacea. Pieces of the integument of the lobster are
commonly found in the stomach-bag, so that it is not at all improbable that the young
lobster sometimes devours its cast-off skeleton. Brook (26) thus speaks of a lobster
the day after ecdysis:

It had partially buried its cast shell under the gravel. During the previous fortnight this
specimen has shown great irritability and pugnacity, and when offered food seized it savagely, but
instead of eating proceeded immediately to bury it.

Spence Bate (9), who tried without success to observe the common green crab
(Carcinus menas) in the act of molting, concluded that this animal had the power of
inhibiting the process until a favorable time arrived.

THE CASTING OF THE SHELL.

A male “shedder” was caught in the harbor of Woods Hole July 13, 1891, and
placed in an aquarium. At exactly 2.48 p. m. this lobster began to molt and in six
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 lost all control over its
own movements. There are other signs, though not equally infallible, which point to
the same conclusion—the dull, faded colors of the old shell, scratched and marred
often with the marks of many conflicts. The shell is frequently of a dark, dirty green
color, the mottled tints having become very much obscured. The contrast in color is
very great if the shedder happens to be among a lot of new-shell lobsters, and the

84 BULLETIN OF THE UNITED STATES FISH COMMISSION.

term ‘‘ black lobster,” used by the fishermen on the coast of Maine, is not altogether
inappropriate. The old shell is also brittle, owing to the absorption of organic matter,
and if the carapace or large shield which covers the anterior half of the body is
pressed between the fingers, it will sometimes split down the back in the longitudinal
median furrow. In most cases the shell does not crack in this place 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 inelastic 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
lobster you will find in place of the median furrow a blue line, drawn as if with a fine
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. In sections of the
skin, however, it is difficult to detect any histological change in this linear area.
Other areas of absorption, to be described hereafter, occur, which are of even greater
importance to the success with which the lobster comes out of his old covering alive
and whole.

The period of uneasiness, which foreshadowed the molt and was very marked,
ended in this lobster by its rolling over on its side, agitating its appendages, and
bending its body in the shape of the letter V, the angle of the V coinciding with the
gaping chink between the dorsal shield and “tail.” Presently the old cuticle, holding
these parts together and through which the new shell is seen, began to stretch, the
wall of the body pressing against it with considerable force, and the hinder end of the
shell 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 nembrane, which finally bursts, revealing the brilliant
colors of the new shell. The legs and other appendages are occasionally moved, but
nomarked convulsive movements are to be seen. The carapace has now become raised
upward to an elevation of perhaps 2 inches behind, in consequence of which, the
anterior end being fixed, the rostrum is bent downward and the animal now has a
very Singular appearance.

When this much has been achieved 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. ‘'he doubled-up fore part of the body is with each effort
of the animal more and more withdrawn from the old shell, and this implies the
separation of the skin from the complicated linkwork of the internal skeleton and the
freeing of the twenty-eight separate appendages, which are attached to this portion of
the body, from their old cases, and at the same time the release of the muscles from the
internal tendons of the large claws and other parts. The cuticular part of every ecto-
dermic structure is stripped off. This exoskeleton folded up to fit such a complicated
mold is in reaiity 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 behind that the rostrum is
directed obliquely downward and backward. The lobster is still lying in comparative

THE AMERICAN LOBSTER. 85

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 furrow. Presently the pressed-down bases of the
antenne, the eyestalks, and the bent-down rostrum of the new shell can just be seen.
No part of the covering of the large claws or of any of the legs has been split or
eracked. The muscular masses of the powerful claws have been withdrawn through
their narrow openings without a rent. Finally a few kicks free the entire anterior half
of the body, the antennie, chelipeds, and various 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 reproduced in the new one, but in the latter the fringes
of stiff setve are as soit as silk, the strong ends of the claws, the rostrum, and every
spine of the body so soft as to easily bend beneath the finger. The large claws are
considerably distorted, as well as some of the other parts, being squeezed 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. Fisher-
men who have had lobsters shed in cars and 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 114 inches. Shortly after the
molt the lobster was 12 inches long. On July 17, four days after molting, the length
was a little short of 124 inches. The increase in length was thus very nearly 14 inches.
The actual increase in size of the different parts of the body can be best appreciated
by comparisons of plates 45 a, and 45 b, which represent life-size drawings of a lobster
before and several hours after the molt. The measurements in this case were 54 and
64 inches, the increase in length being just 1 inch.

Réaumur remarked on the hardness of the flesh of the crayfish immediately after
exuviation, and, as Huxley says (103):

In the absence of the hard skeleton there is nothing to bring the contracted muscles at once back

into position, and it must be some time before the pressure of the internal fluids is so distributed as
to stretch them out.

Hyatt (104) said of the large claws of a molted lobster:

They were exceedingly hard and firm, and I have no doubt would have been extremely good
eating if we had dared to indulge in such extravagance. This is entirely contrary to the usual
accounts, but it agrees with my former observations on the common blue crab, of which I have seen
hundreds directly after molting, and they are always firm and delicious eating if taken at this time.
In fact, the watery aspect usually attributed to the newly molted crustacean did not appear until some
time after the lobster was placed in our live tank.

Very soon after molting the lobster is ready to take food, the body, owing to the

absorption of water, plumps out to its natural shape, and the limit of increase in the
volume of the body is reached.

86 BULLETIN OF THE UNITED STATES FISH COMMISSION.

The interesting observations of Hyatt on the molting of a lobster were made at
Matinicus Island, Maine, July 21, 1880. The ecdysis was accomplished at 9.30 a. m.,
and the lobster lived forty hours, when the shell had become but little hardened, being
still papery and pliable. In twenty-four hours after shedding the claws had swelled
out and assumed a transparent, watery aspect. An under tint of green was observed
in the shell. The crowns and points of the spines and teeth of the large claws had
become whitened. The ratio of increase in buik was found to be 1.211; the ratio of
increase in breadth, 1.192; the ratio of increase in length, 1.010. This lobster came
out of its shell without splitting the carapace, and the ‘“‘tail” was the last part to be
set free.

Vitzou describes the molting of a lobster which he watched in the marine labora-
tory at Roscoff on the 21st of July. He speaks of the membrane between the carapace
as being early ruptured, and points to this as a sign that the animal is about to molt,
but this can not be a normal occurrence.

WITHDRAWAL OF THE LARGE CLAWS.

The shell of the large claws is molted entire without a rupture in any part. This
means that the great mass of muscles which fills the terminal joints must undergo
distension and compression to an extraordinary degree. This will be better appre-
ciated by an examination of cuts 6 and 7, plate B. Cut 6 represents the cast shell of
the left cheliped of the lobster (No. 7, table 24) which molted on July 13, and cut 7
cross-sections of the shell with their plotted areas, in the planes indicated in cut 6.
The flesh which fills the area Ia is drawn through the opening of the joint II (plotted
area Shown in Ila), and later through ITI, the smallest part of the claw. The shell is
here distensible, however, owing to the absorption of lime trom the upper surface, so
that probably in this part the area of the cross-section is increased until it equals that
of Ila. Finally the compressed and distorted limb is drawn through the quadrilateral
opening at the base IV (plotted area, IVa), as Salter says, much as a wire is drawn
through the contracting holes of a draw-plate. The latter is somewhat larger than
the opening of the subterminal joint II. The area of the section of the largest part
of the claw (I, Ia) is more than four times that of the opening Ila, through which all
the tissues of the claw must pass. The muscles appear to be stretched out like a stick
of candy, but, apart from their elasticity, they are probably aided in accomplishing
this by the removal of water from the blood. The parts are very much distorted
immediately after they are free, and are quite hard, but they soon take up water and
assume their natural form, with a proportional increase in size.

The areas of absorption in the three basal joints of the limb are easily distin-
guished, though less plainly circumscribed, in the hard-shell lobster. The shell of the
basal joint becomes a slender ring, which is not broken, as has been inferred, but
remains intact, as Salter (174) has already observed.

In the crayfish, on the contrary, Réaumur (161) maintained that in molting the
shell of the “second and third” joints (meaning, as shown by his figure, the meros and
carpus—fourth and fifth joints) opens by a longitudinal fissure on the outer side.

The two pieces are so perfectly adjusted to each other that they appear as one, but at the time
of the molt, when the crayfish subjects them to strain, these tubes gape apart and thus permit the
passage of the extremity of the limb.

After the molt the crack closes up and appears to be glued together again, as if
no rent had been made. This explanation of the withdrawal of the large claws is

ames

Bull, U.S. F.C, 1895,

The American Lobster. (To face page 86.)

Cur 6.—Left cheliped of lobster seen from the dorsal side. I'rom specimen which molted in an aquarium
July 18, 1891, and which is described in Chapter III, pp. 83 to 85. See No.7, table 24. One-half nat-
ural size.

The Roman numerals I-IV correspond to the planes of section illustrated in cut 7; Arabie num-
erals 1-7 to segments of limb. mb, area of absorption, on upper surface of third and fourth joints.
x, plane of fracture.

882mm? 217mm ? 9377? 2747rm*

I Ul st IV

Cur 7.—I-IV represent transverse sections of cheliped shown in cut 6 in the planes indi-
cated by corresponding numerals, IT and 1V showing the natural openings at the proximal
endsof the sixthand tirstsegments respectively. Ja-IVa represent the areas of the
respective sections expressed graphically and numerically. (The plotted areas are
two-thirds natural size; the numerical expressions above them refer to actual areas.)
At mb, cuts 6 and 7 (III), the lime salts of the shell have been absorbed, so that the
cuticle is capable of distention, and the area of the transverse section is thereby
slightly increased. The muscles and other tissues which fill the transverse section Ia
must be drawn through an opening the size of J7a, then through one but little larger
than I/Ja (allowing for the distention of the membrane), and finally through the small
ring, IV, 7Va, at the base of the limb, since there is no rupture of any of these parts.
Drawings two-thirds natural size.

PLATE B.

Drawn by PF. A. Herrick.

THE AMERICAN LOBSTER. 87

repeated by Rymer Jones (206) and others. It is, without doubt, erroneous, but
possibly based originally upon an exceptional occurrence,

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 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, of course,
was an error. The most significant fact in this process is the displacement of the
liquids which normally belong to these appendages.

Couch (47), in his account of the exuviation of the common edible crab of Great
Britain, Cancer pagurus, maintains that the membranes in the areas of absorption at
the base of the chelipeds split along the edges and open like hinges, thus freeing
the timb from its constraint. This does not happen in the lobster, as Couch inferred,
and even if it did no benefit would arise, since there is the unbroken ring of the
coxopodite, through which the tissues must still pass. Spence Bate (10) thought that
the splitting of the walls of the cheliped, alluded to by Couch, might be to enable “the
animal to withdraw the great osseous tendon.” It is difficult to understand what is
here meant. The great osseous tendons are never withdrawn at all (past the absorp-
tion areas at the base of the limb), but remain attached to the old shell, of which they
form a part.

THE CAST-OFF SHELL.

At the time of the molt there is an intermediate membrane which makes its
appearance between the new and old shells. Itis non-cellular, has a gelatinous appear-
ance, is very transparent, and may be found adherent to the old shell after the molt is
past. When examined microscopically it has the appearance shown in fig. 177, pl. 44.
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 the chitinogenous epithelium underlying the new carapace, which it
traverses by endosmosis. It must be either the first secreted product of the new shell
or the innermost layer of the old shell modified by absorption.

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 isa slight thickening. Réaumur (162) 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 of the body, and which allowed these to glide smoothly over one
another.”

There is normally no rupturing of the shell in any part in the course of the molt.
The entire exoskeleton, with the linings of the cesophagus, stomach, and intestine,
comes off as a whole,' and the animal leaves it by drawing the anterior parts of the
body backward, and the abdomen and its appendages forward, through an opening
made by the elevation of the carapace. When the old carapace falls back into its

'The lining of the alimentary tract is of course ruptured. In small lobsters, at the fifth or sixth
molt, I have noticed that the break takes place not far behind the stomach-bag, and that while the
linings of the masticatory stomach and cesophagus come out by way of the mouth, as in the adult, the
lining of the intestine is withdrawn from the anus.

88 BULLETIN OF THE UNITED STATES FISH COMMISSION.

natural position one might, at the first glance, as Réaumur said of the crayfish, mis-
take the empty shell for another lobster.

In old lobsters, where the membranes are thick, a rupture of the carapace may
arise possibly from want of complete absorption of the lime, but this rarely happens,
and the lobster gains nothing from the complete dehiscence of the parts.

It has been stated so many times that it has come to be generally believed—the
result of the reiteration of error—that the carapace of the lobster is ruptured along
the middle line to assist ecdysis. A careful examination of the cast-off shell, which
would have settled in short order the disputes over this subject, is the very thing
which apparently has not occurred to anyone to make. When this is done, we find
that rupture of the shell is guarded against in the most ingenious way. The areas of
absorption of lime salts in the carapace, which we have only to consider in this
connection, are as follows: (1) The wide lateral margins of the branchiostegites,
including what in life appears as a light-blue area, about three-eighths of an inch wide
in a lobster 10 inches long; (2) a narrow median stripe extending from near the apex
of the rostrum to the posterior margin of the carapace; (3) the endotergites (three
small teeth like projections from the under side of the carapace, on which muscles are
inserted); (4) a linear area on each side of the rostrum; (5) two small round areas in
front of the endotergites—not always noticeable. The linear area (2) extending down
the back acts as a hinge, rupture in the rostral region being provided against by the
narrow absorption areas on each side of it (4), while the softening of the margins of
the carapace makes the lifting of this from the body an easy matter during the molt.
The result of such areas of absorption is plainly to prevent the rupture of the shell,
which, however, does accidentally occur from other causes. The softening of the endo-
tergites is also necessary to prevent injury to the soft tissues.

THE GASTROLITHS.
THE GASTROLITHS OF THE LOBSTER; THEIR STRUCTURE AND DEVELOPMENT.

The gastroliths, though often called crabs’ eyes, are found only in the crayfish and
lobster, so far as is known. Discovered first in the river crayfishes, they early figured
in the old pharmacopeeia as oculi seu lapides cancrorum, and have excited the interest
of naturalists from early times. Owing, however, to their very transitory nature, they
have been generally overlooked in the lobster. A satisfactory explanation of the
function of the gastroliths has, in my opinion, never been given, and in the following
section I shall offer one which I think is in harmony with the facts.

The first reference to these bodies, which I have found, is by Geoffroy the younger,
in 1709 (74), who says, in his paper on the molting of the crayfish:

Although I have spoken only of the stones which are found in the river crayfish, there is, more-
over, a kind of crayfish, called Astacus marinus, in French Homar, in which they also occur.

More particular reference was made to them in 1874 by Chantran (47), and they
are mentioned for the first time in the American lobster by Wheildon in 1875 (202),
who says that “just before shedding a white substance, the size of a 5-cent coin, is found
on either side of the stomach. These bodies harden into limestone and are absorbed
in the process of forming the new shell.” They are described by Vitzou (197) as an
inorganic reserve composed of small truncated rods, free or delicately bound together.

Bull, U S. F.C, 1895. The American Lobster. (To face page 89.) PLATE C.

a b Cc

Cur 8.—-The gastrolith of a lobster nearly ready to molt, removed from the wall of the
stomach.
a, seen from the outside; b, from the inside (toward cavity of stomach), and c, in
transverse section. From adult male, lobster No.2, table 24. For chemical analysis
of this gastrolith, see Appendix II, No. 4a of table. Natural size.

\\) --Wew C
Wify,

aAOLKe (0!

Cut 10.—Section of the deciduous portion of old cuticular
lining of stomach overlying gastrolith. See cut 9, oc!.
89 diameters.

Cut 11.—Section of gastrolithic sac from wall of stomach |
underlying gastrolith, as it appears while the latter is |
still in place in the stomach. From a lobster nearly |
ready to molt. August 2, 1894. See cut 9, gp. 89 diam-
eters.

D, connective tissue of dermis. ep, chitinogenous
epithelium. /c!, new cuticle.

Cur 9.—Diagrammatic section through the wall of the
stomach of a molting lobster, cutting gastrolith.
ep, chitinogenous epithelium. gg, gastrolith, a differ-
entiated part of the old cuticle. gp, gastrolithic sac. n. |
c!,new cuticle of gastrolithic sac. iw, outer side of
stomach-wall next body-cavity. New OC, new cuticle.
oc!, the deciduous part of cuticle overlying gastrolith.
Old C, old cuticle. SS, interior of stomach. WS, wall
of stomach.

Drawn by FP. H. Herrick. 7 ’ a

THE AMERICAN LOBSTER. 89

If the shell of a lobster which is nearly ready to molt is carefully removed, there
will be seen two glistening snow-white masses, one on either side of the stomach
(fig. 184, pl. 44, and cut 9, pl. C). The shape and dimensions of the gastrolith are
shown in cut 8 a-c, pl. C. This particular one, from a lobster 11 inches in length (No. 2,
table 24), was an inch long, three-quarters of an inch wide, and a quarter of an inch
thick. Its outer, convex side is applied to the sac in which it lies, while its concave
surface is separated from the cavity of the stomach by the old cuticular lining of this
organ (cut 9, pl.C). 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 the body
eavity. The impression of the gastrolithic plate is seen on the new cuticular lining
only (n.c.') If the saes in which they are formed are cut open, each mass separates
into a large number—a thousand or more—of ossicles or columns. The majority of
these are slender, truncated prisms of irregular shapes, and 5 mm. or more 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 (fig. 165, plate 42).

On August 2, 1894, I examined a lobster which was very nearly ready to molt.
The old shell came off easily. The gastroliths were fully formed. We can detect upon
the new cuticular wall of the stomach the gastrolithic plate, from which the next
gastrolith will be formed. When the old cuticular lining ot the stomach is removed
the new teeth appear of the same brown color and nearly of the same hardness as the
old. The supporting calcareous parts are, however, quite soft. (For analysis of these
gastroliths, see No. 3a of table, Appendix II.)

The gastrolith shown in its natural position in the sac (fig. 184, pl. 44) was from a
male lobster 7.5 inches long. This is the smallest animal in which I have found these
structures, and it is possible that they are not developed until the lobster is several
years old, although I have not obtained enough material to establish the time of their
first appearance with definiteness. A female lobster 3+} inches long, which was taken
in Small Point Harbor, Maine, by Mr. M. B. Spinney, was as soft as wet paper, and had
apparently just molted. Upon dissecting this animal I was surprised to find the
stomach stuffed full of fragments of calcareous matter, consisting chiefly of waterworn
pieces of the shells of dead mollusks, such as are commonly thrown upon a beach.
The largest of these fragments was a quarter of an inch long. Many of the shells
were softened or corroded and were easily broken by needles. There were, besides, a
considerable number of small moliusks, such as the young stages of Mytilus edulis.
Some of these shells, when devoured, were undoubtedly alive. No trace of gastroliths
could be seen. The old cuticular skeleton of the stomach had been discarded, and the
new “teeth” were but little hardened, save upon their brown, horny surfaces.

Another small lobster, a male, 4,2; inches long, taken at the same place and at
about the same time, had recently molted, probably within a few days. The shell was
very delicate and fragile. In this case, also, the stomach was loaded with fragments
of the dead shells of mollusks, crabs, and small lobsters. The hardest parts of the
Shells of the latter seem to have been chosen, such as the stony mandibles, spines, and
teeth of the large claws. There was no fleshy substance which might serve as food in
this stomach. It is possible that these shells are swallowed by the young lobster, after
cach molt, to furnish lime for the hardening of the cuticular skeleton. The absence of

90 BULLETIN OF THE UNITED STATES FISH COMMISSION.

gastroliths may have no significance in these cases, but in order to determine this
one should examine the stomachs of larger animals which have recently molted under
natural conditions.

The gastroliths, though a part of the cuticle, are not cast off during the molt, but
are retained in the stomach. When the old lining of this organ is withdrawn, the
gastroliths are soon set free, and breaking up into their constituent parts are speedily
dissolved.

In the lobster referred to above (No. 2, table 24), which was preserved immediately
after the old shell was shed, the gastroliths were still in place in the stomach, and
unchanged. (For chemical analysis of these, see table, Appendix II, No. 4a.) The
-horny parts of the gastric ossicles agree closely with those of the cast shell, having
the same light-brown color and approximately the same hardness. The supporting
calcareous parts are, however, quite soft. In every case which I have examined, the
old teeth are expelled from the stomach at the time of ecdysis, and not left with the
gastroliths, as Réaumur (167) said was true of the crayfish.

Experiments upon the crayfish have seemed to show that the gastroliths are
necessary for the hardening of the new shell, but this is undoubtedly an error.

The length of time required for the development of the gastroliths of the lobster
has not been determined. It is probable, however, that the latter part of their devel-
opment is rapid, and that they are conspicuous objects for a few days only before the
Shell is cast off.

A female lobster which was examined August 10, 1893, had a very hard, dull-
colored shell, which one might infer would be shed before many weeks. In place of
the gastrolith there was a very thin gastrolithic plate in the lateral wall of the stomach
(fig. 183, pl. 44). A section through this plate (fig. 171, pl. 43) shows how the gastrolith
is developed. The cuticular epithelium is columnar, consisting of very long, slender
cells. The thick excreted cuticular product is traversed by undulatory striations,
which mark off the columnar ossicles, the separation of which begins at the outer
surface.

The inner section of the gastrolithic plate (G P) appears much more homogeneous
than the outer portion, although the demarcation is not quite so sharp as appears in
the figure. The striations in the inner part are only conventionally represented. The
undulatory striz extend inward, and with the deposition of lime the ossicles are
developed and completely separated. When the gastroliths are fully formed (cut 9,
plate C) the deciduous cuticle of the gastrolithic sac is differentiated into two parts,
the gastrolith (gg) and a thin outer layer (oc', cuts 9 and 10) corresponding to the
outermost part of the cuticle shown in figure 171 and in continuity with the old lining
of the stomach (Old C). The new cuticle of the stomach (New C) is represented in
the gastrolithic sac by a thin stratified layer (nc, cuts 9, 11), from which the next
gastrolith will be developed.

The condition of the gastrolith at this stage bears a resemblance to that which is
finally reached in the crayfish, where, according to Huxley (103):

It is a solid body which, in vertical section, is seen to be composed of thin superimposed layers,
the densest of which form the hard projections of the outer surface next the epithelial substratum.

The outer side of the gastrolith in the crayfish is roughened with irregular promi-
nences, so that it resembles a “‘ brainstone” coral. When from any cause the stones
are not dissolved, they lose their normal blue or white color and become brown or green;
the shell remains soft and the animal, according to Chantran, soon dies. When the

THE AMERICAN LOBSTER. 91

formation of the stones is arrested, as Chantran had often observed in October and
November, the crayfish was unable to molt, and died.

Chautran (42) presented to the Academy of Sciences of Paris a paper, giving an
account of the natural concretions, called ‘“ crayfishes’ eyes,” produced from the time
of birth in this crustacean up to the age of six years—that is, during 22 successive
molts. It was found that the stones are not absorbed at the moment they become free
in the stomach, but that they are gradually worn down by reciprocal rubbing and
contractions of the stomach. The plane faces of the stones are thus rubbed together
until they are gradually worn down, and at the tenth hour after ecdysis they are
reduced to pellicles of 1 to 2 mm. in diameter. The destruction of the concretions
may be complete at this time, or they may persist up to the eightieth hour.

According to Chantran (41, 42), the number and succession of molts in the Euro-
pean crayfish are as follows: First year, 8; second year, 5or6; third year, 3. After the
third year the males molt twice and the females once annually. He further believed
that every molt involved the formation of calcareous masses in the stomach, and that
these numbers consequently show how often the gastroliths have been formed and
used up. The time occupied in their formation increases with age, being 10 days the
first year, 15 days the second, 25 days the third, and 40 days in subsequent years.
The time which elapses after the molt before the stones are reabsorbed also varies
with the age of the individual, from 24 to 30 hours in the young, which have not
molted more than twice, to from 70 to 80 hours in adults.

HISTORY OF THE GASTROLITHS—THEIR PROBABLE FUNCTION.

The gastroliths were the subject of much curious speculation among the older
naturalists—Gesner, Bellonius, and Agricola—who, according to Herbst, assigned
to them a position in the brain. Van Helmont, who first described their true position,
was not far from right in thinking that they were formed by a milky secretion which
was poured out between the old and new linings of the stomach. Geoffroy’s observa-
tions (74), published in 1709, were the best made up to his time.

I have opened [Geoffroy says] vigorous crayfishes which had entered upon the process of molting
and have found in the place of each stone ascale or white plate, which swims in the middle of a mucus,
and which was apparently the undeveloped condition of the stone. This stone and the glairy liquor
were enveloped in a small, membranous, and very delicate sac.

In ecrayfishes which have recently molted the stones are not in their usual places,
but lie in the stomach, joined together by their concave parts. No vestige of a stone
was found in the stomachs of crayfish in which the shell had hardened after molting.
He concludes however that the stones play no part in the formation of the new shell,
although they appeared to serve as food after the molt.

Réaumur (162), besides repeating Geoffroy’s observations, added much that was new
to the subject, and placed the general facts of the molting of crustacea beyond the
doubts which had existed up to his time. By dissecting crayfishes which had molted
he found that the stones gradually dwindled and disappeared. He says:

Is it not natural to suppose that these stones are dissolved, and that their substance is then
carried and laid down in the interstices of the fibers of which the skin is composed ?

Roesel (268), in his beautiful Insecten- Belustigung, published in 1755, discusses at
some length the function of the gastroliths, coming to the conclusion that they are
useless material which is formed during the molt, to be afterwards expelled from the

92 BULLETIN OF THE UNITED STATES FISH COMMISSION.

cesophagus. According to Mayer, whom Roesel quotes with some reserve, it was the
custom of the inhabitants of Asiatic Tartary and Ukrania to collect crayfish at the
time of the year in which they were in the best condition and place them in large pits
in the ground. Here they were broken up and allowed to remain all winter, during
which time the evil odor kept everybody away. In the spring the owners would
return, wash out the remnants of the crayfish in water, and sift out the stones with a
sieve which they used for this purpose. It was formerly the custom also in Poland
and Rassia, on the River Don, to collect crayfish in large quantities and allow them
to rot in the fields or in pits. The stones were afterwards carefully collected and sent
to market to be used as medicine.

Mr. Baker (7) communicated to the Royal Society on February 25, 1748, an inter-
esting letter on ‘“‘crabs’ eyes” from Dr. James Mounsey, a Russian physician. He
noticed the seal-shaped spots on the wall of the stomach, which mark the position of
the developing gastroliths, and concluded that the latter helped to form the new shell,
which, he says, ‘‘does not greatly recommend the opinion that these stones have a
dissolving quality of service against the stone in the human kidneys and bladder.”
“The price comes to a groat or sixpence a pound. All the apothecary shops through-
out the whole Russian Empire are furnished with them, and great quantities are
exported.” Notwithstanding their cheapness, “fictitious bodies, made of chalk” and
““tobacco-pipe clay ” were cast in molds and substituted for real ‘crabs’ eyes.” In
this case the counterfeit undoubtedly possessed all the virtues of the genuine article.

K. E. von Baer (6) thought that the gastroliths were salivary stones, developed
in the lumen of a salivary gland, an idea which was not destined to bear much fruit.
Some writers even pretended that they were cast out through a fissure in the walls of
the stomach and body.

Van der Hoeven (195) seems to have been one of the first in the present century
to protest against the theory that the sole function of the gastroliths was to provide
lime for the new shell. In his Handbook of Zoology, a translation of which was
published in 1854, he says: -

The part, however, which the crabs’ eyes take in the secretion [of the hard shell] can not be
great when we compare their weight with that of the calcareous matter of the shell. During the
time that the shell is still increasing in hardness no new crabs’ eyes are produced; but only after
the shell has attained its greatest hardness is calcareous matter again secreted on the walls of the
stomach, and new crabs’ eyes again appear. Thus the production of crabs’ eyes would seem to be
a vicarious secretion of such constituents of the blood as, if too abundant, would be injurious to the
organs, like the secretion of urine for instance, but with this difference, that the calcareous matter is
not set at liberty shortly after its secretion, but remains accumulated for a long time in continuance.

Max Braun, in his work on the molting of the crayfish (22), concluded that the
gastroliths were cuticular products analogous to the integument, but paid no attention
to their function or growth.

Vitzou (197) says that shortly after the molt in the lobster the gastroliths are dis-
solved in the acids of the stomach and, entering the lymph, form an inorganic reserve
comparable to the phosphatic plaques which are found in the membranes of the foetus
in ruminants.

The problem of the gastroliths has recently been attacked by Irvine and Wood-
head (105) in one of their valuable communications on the secretion of carbonate of
lime in animals. They conclude that, if the gastroliths play any part at all, they must
be converted into phosphates and thus carried in the lymph. If the brachyura have

THE AMERICAN LOBSTER. 93

a lime reserve, it must be in the lymph, in the form of calcium phosphate, since they
have no gastroliths. ‘We think,” they say, ‘‘that this theory [of the gastroliths
contributing to the formation of the new shell] may be dismissed as of comparatively
little importance, since, even if the teeth and whole calcareous structure could be
absorbed by the animals, the amount of carbonate of lime at their disposal from this
source is So Small (a very small fraction of the outer covering) that it could not account
for any considerable part of the new structure. Consequently such an explanation
must be abandoned.”!

These writers are undoubtedly right in attributing little importance to the gastro-
liths as a source of lime for the new shell. Lime is usually at hand in abundance in
the form of the dead skeletons of mollusks and other animals, and, as we have seen
(see p. 89), young lobsters make free use of it at the time of the molt. The fact that
the brachyura have no gastroliths should also possess some significance.

I have already shown that there are considerable areas in the shell where the lime
is completely absorbed preparatory to the molt. What becomes of the lime thus
removed? So faras known, there is no means of eliminating it directly from the body,
and it is not likely that this amount of lime can be retained in the blood in addition to
that which the latter is constantly receiving from the food. It seems to me much more
probable that the gastroliths in the lobster represent the lime which has been removed
by absorption from the old shell preparatory to the molt, as well as, possibly, a small
amount which may have entered the blood from the food during the molting period.
The blood probably contains a maximum quantity of lime at this time, so that very
little can be absorbed from the food. Upon this hypothesis the absorption of the gas-
troliths is a purely secondary phenomenon and of comparatively little importance in
the vital economy. In the brachyura, where no gastroliths are developed, we should
expect to find the absorption of lime from the shell to be relatively much less, which,
so far as I can ascertain, is the case. Jt seems to be a fact also that the absorption of
lime froin the old shell proceeds pari passu with the growth of the gastroliths.

Chantran observed (see p. 90) that when the formation of the stones was
arrested in the crayfish the animal died. This might be true of the Jobster, and
would not conflict with the theory proposed. When once formed, the question of the
subsequent absorption of the gastroliths is not of vital importance. Vitzou speaks
of a lobster which died six days after the molt, without absorption of the gastroliths
having occurred. It would, of course, be very illogical to conclude that the gastroliths
were necessarily in any way concerned with the death of this animal.

‘In an interesting letter from Dr. Irvine, describing some of his recent experiments, he says in
reference to a former attempt to determine the proportionate quantities of carbonate of lime in the
exoskeleton: ‘But as these experiments were made with the common shore crabs, containing much
less carbonate of lime proportionately to a full grown animal, I have repeated the determination,
using a full-sized lobster which weighed 15,000 grains. On carefully separating the stomach, and
freeing it from merely fleshy appendages and drying it, I find it to weigh about 50 grains or +3; of
the whole animal, while the gastroliths weighed only 20 grains or 735 of the whole. I then carefully
dried the outer calcareous structure and found it to weigh 3,720 grains, the proportion between
the carbonate of lime in the gastroliths and in the outer structure being 20 grains to 3,720 gr ains
The CaCo; in the gastroliths thus stood in proportion to the CaCo; in the exoskeleton as 1 part in 186,
an amount too trifling to be of any practical service in providing calcareous matter for it.”

94 BULLETIN OF THE UNITED STATES FISH COMMISSION.

CHEMICAL ANALYSIS OF THE SHELL AND GASTROLITHS.

It seemed to me that a chemical analysis of the shell of the lobster in its differ.
ent conditions imposed by the molting habit might prove of interest, especially when
compared with the composition of the gastroliths, and I am fortunate in being able to
add as an appendix of this work the results of several analyses made by my friend,
Professor Albert W. Smith.

The most striking facts brought out by Professor Smith’s work are, first, that lime
salts, 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 brittleness of which we have already noticed,
the proportion of organic matter present is considerably less than under other condi-
tions. 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.

It is also interesting to notice that small quantities of alumina and silica are
normally present in both the shell and gastrolith.

The composition of the gastroliths is very like that of the shell, a conclusion
which we would be led to draw from the fact that the gastrolith is but a specialized
part of the dead chitinous integument. The same substances are found in both, but
in different proportions. The gastroliths are far richer in lime, chiefly in the form of
carbonate (CaCO;), than is the shell, and the amounts of magnesium carbonate
(MgCO,), alumina (A1,O,), ferric oxide (Fe,O;), and silica (SiO.) are more or less reduced.

Lime estimated as carbonate (CaCO;) constitutes about three-fourths of the
gastrolith, but less than two-fifths of the carapace. Lime reckoned as phosphate
(Ca;(PO,).) forms about 10 per cent of the gastrolith and but little less in the case of
the shell; about 10 per cent of the gastrolith is water and organic matter, probably
mainly chitin, and the rest is made up of the various salts and oxides given in the table.
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.

The gastroliths of the crayfish were analyzed by Dulk (54) in 1834,' but apart from
this rough determination no later work has been done on this subject.

He also analyzed the contents of the stomach of a crab newly moited, and found
a free volatile acid, probably hydrochloric, present, besides lime salts (53).

THE HARDENING OF THE NEW SHELL.

Since the total quantity of lime contained in the gastroliths is insignificant com-
pared with 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. We have seen that the adolescent lobster,
under 4 inches long, after molting swallows fragments of shells and other calcareous
materials, which are dissolved in the stomach and help in strengthening the new shell.
It is possible that older lobsters have the same habit.

1 The results of Dulk’s work were as follows:

Animal matter solublesin waterkes os) peeee see eeneee SEES eee eae 11. 43 )
Animal matter insoluble in water (probably chitin—Huxley)-.-..-...----.------ 4. 33 |
Phosphate:of lime: 2 5 2. je2 eS ee eee eee eee 18. 60 > 98. 93
Carbonate‘of lime... 022. < jcccch 2 Je eee ee eee 63. 16 |

THE AMERICAN LOBSTER. 95

According to the researches of Irvine and Woodhead lime salts, in whatever con-
dition absorbed, are changed during digestion into acid phosphates, and in this state
are carried by the blood to the protoplasm of the chitinogenous cells. The nascent
carbon dioxide gas, which the active protoplasm of these cells throws off, precipitates
calcium carbonate (CaCO) and calcium phosphate (Ca,(PO,).). These salts are then
dialyzed into the dead chitinous matrix, where they are finally laid down. Lite is
deposited in an insoluble condition only in vitally inactive tissues. They found that
crabs which began to shed late in the season were retarded by the cold. Heat thus
seems to be a necessary factor in the assimilation of lime salts from seawater by these
animals. They also found that the crabs died in water containing only sodium chloride
(NaCl), but lived without molting in water containing NaC] and magnesium chloride
(MgCl.); they lived and molted in water which contained NaCl, MgCl,, and calcium
chloride (CaCl,), the latter in the amount equivalent to the lime in normal sea water.

A lobster which molted while under observation (No. 7, table 24) 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 partially due to the turgescence of thetissues. Eighteen hours after shed-
ding 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.

A lobster which also molted in confinement (No. 6, table 24) was kept for a period
of twenty-five 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 using considerable force. It was in the state which the fisher-
men call “paper shell” or “rubber shell.” If sent to market it would be classed as a
soft-shell lobster. It is possible, of course, that in this space of time a lobster under
natural conditions would have become harder. It is safe to conclude, however, that
from six to eight 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 ten weeks or three months. Many
lobsters are caught and shipped to dealers a few weeks after they have molted, but
their meat is then soft and of inferior quality, as we have already remarked. 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 fleshis more solid.

Réaumur says of the crayfish (162) that he has seen the new shell become as hard
as the old in 24 hours, but that it usually takes from two to three days. This observa-
tion is confirmed by Chantran (37), who says:

Twelve hours after the molt, the nippers are already hard enough to pinch sharply, and in 24
hours they are completely hardened. The sides of the back remain flexible for a much longer time,
but at the end of 48 hours they have attained a degree of consistency which is almost normal.

Vitzou remarks that the carapace of the crabs has perceptibly hardened after 24
hours, but is not completely hardened until after 72 to 80 hours.

It has been stated that the shell of the newly molted lobster becomes as hard as
formerly in the space of 24 hours. This and many similar conjectures which have
been made upon this subject are entirely erroneous, as proved by the statistics of the
fishery during the summer months. It is probable, however, that under exceptional
conditions this process is subject to much variation.

96 BULLETIN OF THE UNITED STATES FISH COMMISSION.

THE RATE OF GROWTH.

The question often asked is, How long does it take an adult marketable lobster to
grow? It is impossible to answer this 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.

In order to ascertain the average age of a lobster 104 inches long (weight, 12
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. The number
of molts can be approximately determined by means which I shall presently discuss.
The time interval can only be ascertained by keeping the animals alive for a period of
years and carefully recording their growth. Both factors are very variable quantities,
as I have already shown. The length of one yearling lobster which was raised from
the egg was only 36 mm., while three other lobsters easured from 35 mm. to 51.8 mm.,
when not over five months old. Lobsters which live in harbors where they find abun-
dant food undoubtedly grow much faster than those farther from shore. It would
hardly be expected, moreover, that lobsters kept under artificial conditions would
grow as rapidly as when free in the ocean. !

In table 24 I have recorded the molts of eight lobsters varying from 54 to 114
inches in length. The actual increase in length varied from 1 inch to 13 inches, and
the increase percentage (that is, the ratio which the increase bears to the total length
before molting) from 6.66 to 18.18. The average percentage of increase in all these
cases 1s 12.01.

TABLE 24.—Jncrease in the length of lobsters at the time of molting.

| Length | Length
No. Date. | Sex. before the) after the
molt. molt.

Increase Increase

in length. percent. Remarks.
| |

Inches. | Inches. | Inches.
1 | Oct. 22,1890) Female .| 54 63 1 18. 18 Carapace of molted shell unbroken;
- preserved a few days after molt-
ing; gastroliths gone; stomach
filled with pieces of fish, which
had been ted to it; carapace
leathery. Plates 45a and 45b.

2 | Oct. 29,1890} Male.... 11 12 1 9. 09 Carapace unbroken; preserved im-
mediately after molting; gastro-
liths in their saes in the walls
of masticatory stomach. See cut8,
plate C. For chemical analysis of
gastroliths, see Appendix II,
| No. 4a of table.

3 | Nov. 6,1890}...do-..-. 74 8h 3 9. 68 Carapace unbroken.

de None 0%1890)) ee cee estas 9 104 13 16.66 | Do.

5 | Nov. 11, 1890|.......--. Th 8 4 6. 66 Do.

6 | June 8,1891|...do.... 93 104 14 13.13 Carapace unbroken; measured July

2. See table 28.

7 | July 13,1891 |...do-.... 113 124 14 11.11 Carapace unbroken; measured July
| 17. See account of molting of this
| | | lobster, pp. 83-85; also plate B.

CH ei aoe ee | Sees 63 TA | 3 154 | Recorded by Packard (147).

Average -. soretteeeees |Semteaeeerrel| ere setererteret looasunees 12.01

\The best way to ascertain the growth of the lobster would be to fence in securely with wire
netting a convenient area in a lobster pound, place a few lobsters in the inclosure, and feed them reg-
ularly. They should be examined every week and carefully measured. They could be distinguished
by branding the tail-fan. By selecting lobsters of different sizes (3, 5, 8, 10 inches long), the rate of
growth at different periods of life could be gradually determined.

THE AMERICAN LOBSTER. oT

The increase per cent in the growth of larve is recorded in table 34. Sixty-six
molts belonging to more than half as many individuals are tabulated. The average
increase per cent in length in stages 2 to 10 varied from 11 to 15.84. The average for
stages is 13.67; for individuals, 13.89. These facts seem to warrant the conclusion
that the increase percentage in the young is very similar to that of the adult, a result
of considerable interest. The average length of the young lobster during its first ten
molts is given in the following table. The data are taken partly from table 354:

TABLE 25.—Actual length of lobsters during the first ten molts.

a | mete eet chs Number of
Number of molt or stage. Tete | Ea ees um lobsters
are bed examined. |
mm. mm.
1 7. 84 7.50 to 8, 03° 15
2 9. 20 8.3 10. 2 47
3 Wht al 10 12 79
4 12.6 11 14 64
5 14.2 13.4 15 15. |
6 16.1 15 17 12
7 18.6 18 19.5 4
cue 21. 03 19.75 22 5 |
9 | 24.5 24 25 2 |
10 | 28. 03 26.6 29.5 3)
1

The rate of growth expressed by the average of lengths in the second column
of table 25 implies an increase per cent of about 15.3 instead of 13.67 (the average
increase in stages recorded in table 34). Assuming the average length of the first
larva to be 7.84 (the average of 15 individuals, table 25), and allowing the increase in
length at each molt to be 15.3 per cent of the length before molting, we would have
the following series of lengths attained during the first thirty stages.

TABLE 26.—LHstimated length of lobsters during the first thirty molts.

|
Stage. Tenet Stage. Length. | Stage. ‘Length.

mie. |
1 7. 8d. |
: 9.04 |
|
|
}

mm. | mm.
WS ogascnnos 32.55 || 21.....-...-- ; 135.17

10, 42
12. 02 |
13. 86
15. 98
18. 42 |
21. 24 ||
24. 49 bike
28. 23 || 2

19.5 inches. 211 inches. 319.1 inches.

According to this estimate a lobster 2 inches long has molted 14 times; a lobster
5 inches in length, from 20 to 21 times; an adult from 10 to 11 inches long, 25 to 26
times, and a 19-inch lobster 30 times. These estimates do not, I believe, go very
far astray. We see them practically verified up to the tenth molt by comparing the
figures given above with those in the second column of table 25,

The time interval between successive molts is the next point to consider. The
yearling lobster undoubtedly varies greatly in size. A young female lobster already
mentioned reached the length of 51.8mm. by December 10, or when from five to six
months old (No. 19, table 33). On the 28th of January 16 small lobsters, measuring

from 39 to 83,7 mm. in length, were driven ashore at Woods Hole during a storm, It is
F. ©. B, 1895—7

98 BULLETIN OF THE UNITED STATES FISH COMMISSION.

certain that some and possibly all were hatched in the preceding summer. Allowing
the lobster (No. 19, table 33) whose length was 51.8 mm. long on the 10th of December
to have molted, in case it had lived, three times before the following June, and this is
well within the bounds of probability, it would then have attained a length of a little
over 3 inches. During the first year the young lobster probably molts from 14 to 17
times and attains a length of from 2 to 3 inches, but it is likely that the length reached
often exceeds these limits.

Of the young lobsters recorded in table 32 a few may be the young of the year
(Nos. 1-4), that is hatched in the previous June, but the majority are probably from
one to two years old. It is further possible that some of these were hatched at other
times of the year than June.

Brook appears to be the only one who has given a trustworthy account! of the
“successive molts of individual lobsters. He succeeded in keeping a lobster (female,
length 632 inches) alive in an aquarium 506 days, from July 1, 1883, until November
19, 1884, during which time the animal molted four times (on July 1 and December
25, 1883, July 25 and November 19, 1884) and increased in length 2,4; inches. During
the first year of its captivity it molted twice, in summer and early winter; again it
molted in summer and late fall. The lengths at successive stages were as follows:
618, 733;, 8, 814, 958; inches.

In another captive lobster (a male, length 7-’; inches) four molts were also passed,
one in the spring and fall of two successive years (May 19, September 20, May 13,
October 13). The lengths at successive stages were as follows: 7,3;, 743, 843, 9:5, 942
inches. There was an increase here in length of 25%; inches in 414 days.

These experiments are instructive in showing that in the unfavorable conditions
of life in an aquarium a lobster from 6 to 7 inches long will make a gain in length of
25 inches in 14 to 17 months. It is therefore extremely likely that in nature a 6-inch
lobster will often attain the length of from 9 to 10 inches in two years.

How long a time is the 3-inch yearling lobster growing to become 6 inches in
length? Reference to the series of molts given in table 26, deduced from study of
the young, leads us to expect five molts (Nos. 18 to 22) between the 3 and 6 inch stages.
It is certain that these do not embrace more than two years, and it is probable that
they require somewhat less. We may therefore conclude that a 10-inch lobster is
between four and a half and five years old, the higher degree of probability favoring
the smaller number.’ The reader is reminded 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.

‘Buckland (29) says that ‘‘according to some careful observations made at the marine labora-
tory, Concarneau, it appears that the first year the lobster sheds his shell six times, the second year
six times, the third year four times, and the fourth year three times.” If this were amended so as to
read careless instead of ‘‘ careful” observations, no complaint could be made. We have seen that
the American lobster molts ten times in the space of three or four months, and it is not probable that
the record is very different for the Englishspecies. No crustacean is known in which the molts are as
numerous during the second year of its life as during the first. A table is also given by Buckland
showing the rate of growth during successive molts, but it seems to be based upon error. At the eighth
molt the lobster 1s said to be 2 inches long, whereas the American lobster is less than 1 inch in length
at the eighth molt (21 mm., see table 25), and there is no reason to believe that the European species
is more than twice as large as its near ally at this stage.

>Coste maintained that the European lobster was about 5 years old (length 24 cm.) before
becoming sexually mature, and this supposition, though unsupported at the time by any detailed
facts, seems to be very near the truth. (See 6/, p. 285.)

=

THE AMERICAN LOBSTER. 99

Vitzou records the following observations (197) upon the increase in size and
weight of molting lobsters. In a lobster which was measured immediately before and
after the molt it was found that the carapace had gained 11 mm. in length and the
abdomen 8 mm. The last joint of the right claw was smaller by 3 mm., which is
explained, first, by the thickness of the chitinous layer in this joint, and, secondly, by
the almost complete absence of blood in the claw at this time. This is a forced con-
dition, since if the last joint of the claw were increased in size it would be next to
impossible for it to be withdrawn (see pp. 86-87). The same lobster 17 hours after the
molt showed no increase in size of carapace or abdomen, but the claws had gained from
12 to 15 mm. in length. No increase in any of these parts was noticed on the third to
the sixth days following the molt, but there was a gain in weight.

7

TABLE 27.

Time of observation. Weight. Increase.|

|
|

Grams.. Grams.
Immediately after molt..................... P=) heeenenbee |
The day following molt. -- oe 610 100
Mhirdiday following molto ss sece eae eee seen cisan asses 2- 619 9
Fourth day following: molt 22. --2-)-s-222-6 ses2s2s2 2 s<qdne- sc: | 642 23
Fifth and sixth days following molt....--...-..-.------..--. | 642 0

The following measurements show the increase in various parts of the body after
the molt. They refer to lobster No. 6, table 24 (compare plates 45a and 45d):

TABLE 28.

Before Five days Increase |

MCPS UGnGat molt. after molt. |
|
Inches. | Inches. Inches.

IbSPAaN, Baaanaecocse senauode cooooonGoocenoESES 9. 28 10. 50 1, 22
Length of carapace. .--....---.--------------- 4, 33 5. 08 -70
Greatest width of carapace........---------- 252 PBB} | “13
Length of crushing-chela (propodus).-.-..-.., 4,12 5. 62 1.50
Width of crushing-chela at base of dactyl. 2. 06 2. 56 - 50
ene thiofadactylemecessesmmrcssese ace ce aanee 1.90 2. 25 85
Width of dactyl at base.-.....-......-----.. - 72 1. 00 - 28
Length of small cutting-chela (right)... ..--. 4.53 5. 53 1.00
Width of small cutting-chela.---..-....----- 1.53 1.47 — .06
Mong thwotedactylesenss-eeen cere tee eee ee 2.53 | 3.06 | - 53
Wiidthiottd acetyl Sas seeessees eee eeerer sees | 56 | 65 09

Chapter 1V.—DEFENSIVE MUTILATION AND REGENERATION OF LOST PARTS.

AUTOTOMY IN THE YOUNG AND ADULT. ~

It is well known that among the invertebrates the crustacea possess, in a
remarkable degree, the power of reproducing parts of their bodies which have been
lost. This is most pronounced in those Decapods, such as the crab and lobster, which
practice defensive mutilation or autotomy. Thus, if one catches a land crab and holds
it by the carapace it brandishes its chelipeds in its vain attempts to get free, but once
seize it by the claws, the crab immediately scuttles off, leaving you in possession of
its only effectual weapons. The leg is broken off at a definite place near its base;
there is very little bleeding from the old stump, and a new limb soon sprouts and
grows again. This power of thus detaching a limb at the right time is a valuable
means of defense, which, as Pere Du Tertre remarked, would be very useful for pick-
pockets. The lobster has the power of casting off its legs, but those which carry the
‘“nippers” are the most commonly sacrificed.

The limb (cut 6, plate B) consists of seven joints, two basal ones—coxopodite (1)
and basipodite (2)—and five succeeding joints, the last two of which form the claw
(6 and 7,cut 6). In autotomy the five terminal] joints are always cast off; that is, frac-
ture takes place between the second and third segments. In the large chelipeds of the
lobster the second and third joints—basipodite (2) and ischiopodite (3)—are fused
together. This is the case in-all the pereiopods of the crab. There is a distinct groove
which marks the union of the two fused joints, and it is always in this groove that
disjunction occurs (x, cut 13, plate D). This fact was noticed by Réaumur (167) at the
beginning of the last century, but he did not offer an explanation. He noticed that it
was not at the functional articulation that the limb was broken, and that the shell of
the “second joint” (second and third, cut 13) was “composed of several different
pieces. The evidence of this was found in the presence of two and sometimes three
sutures, which occur in this part. It is in the middle suture, moreover, that the leg
is broken.” He noticed also that the leg could be broken off by exerting very little
force. The interesting fact did not escape his attention that if you cut off the leg at
or near the terminal joint you will find after a time that the mutilated limb is always
thrown off at the suture between the second and third joints.

Fredericy (77) has published several papers on the defensive mutilation of the
crab, and has given a physiological explanation of this phenomenon. I will now add
a brief abstract of some of his experiments, which were performed chiefly upon the
common green crab, Carcinus menas.

The breaking off of a leg, which so often happens when we handle these animals,
is not due to their fragility, for experiment proves that the limbs of a dead crab are very
resistant and that they will support a weight of 34 to 5 kilograms (7.7 to 11 pounds),
which represents about one hundred times the weight of the entire body of the animal.
If one breaks off a leg of a dead crab, it separates either between the cephalothorax
and first joint, or between the first and second joints, and a mass of muscles is usually
drawn out of the body with it. The fracture of the leg of a living crab occurs, as we

100

Bull, U.S. F.C.1895. The American Lobster. (To face page 100.)

PLaTeE D.

iN
oy
Cur 12.—First left pereiopod of adult lobster, seen from in
front, showing anterior border at base of limb. Two-
thirds natural size.
a, b, constrictions in cuticle of third joint. ¢, oblique
linear impression upon upper surface of second joint.
x, plane of fracture. 1-5, segments of limb.

Cur 13.—Basal portion of first left pereiopod of adult lobster from under side. Two-
thirds natural size.
a, b, grooves on surface of third joint external to. Br, podobranchia. «x, plane
of fracture. y, spur of second joint. 1-6, segments of appendage.

Cut 14.—Second left pereiopod of female, 10 inches long, seen from under side.
Two-thirds natural side.
a, constriction upon second joint immediately in frontof «. Br, podobran-
chia. 2, articulation between second and third joints, corresponding to plane
of fracture in cuts 12 and 18. y, spur on second joint.

Drawn by F. H. Herrick.

BGs?

THE AMERICAN LOBSTER. 101

have seen in the large cheliped of the lobster, in a definite plane. It involves only the
nerves and blood vessels of the soft tissues, and is provoked by a vigorous muscular
contraction, which occurs whenever the nerve of the leg is stimulated violently, whether
bya mechanical stimulus, as by snipping off the terminal joints, or by electricity, heat,
or chemical action. The nervous mechanism is reflex, and thus beyond the control of
the animal. Autotomy occurs when the whole of the dorsal and cephalic regions of
the body, including the supra-cesophageal ganglion or brain, is removed. The reflex
nerve center is found to lie in the thoracic ganglionic mass of the crab, or ventral nerve-
chain of the Macrura.

The second compound joint is moved by two muscles, a flexor and an extensor,
of which the last only is essential to autotomy. Fracture of the limb was produced so
long as the extensor muscle and its tendon were unimpaired, but > EEE these were
sectioned autotomy was suppressed.

The mechanism of the crustacean limb has been explained by Milne Edwards
(58, vol. 1, p. 152). The leg consists, as we have already seen in Decapods, of seven
joints, each of which is a lever of the third order. Any two joints are articulated like
a hinge, touching at only two points, and are capable of simple extension and flexion
only. The whole limb, however, is capable of executing complicated movements, since
the axes of articulation of the several segments are not parallel, but nearly at right
angles to each other. Each segment possseses two or more cuticular tendons at its
proximal extremity, upon which its flexor and extensor muscles are inserted, the fibers
of the latter being fixed upon the inner surface of the next proximal joint.

Fredericq has shown that the distal extremity of the second joint, or basipodite, is
separated from the third joint, or ischiopodite, by a diaphragm, perforated near its
center only, for the passage of the nerves and blood vessels; and Andrews (3) has
pointed out that ‘*in the spider crab, Libinia canaliculata, there extends from the plane
of rupture” a distinct membranous fold, ‘‘from the epidermis to the central nerve and
blood vessels.” With the rupture of the limb the outer half of the membrane is torn
away, leaving a clean stump. This double membrane possibly represents, as Andrews
suggests, the invagination of the body wall, like that seen at an ordinary movable
joint. This membrane has thus experienced a complete change of function, and has
become modified so as to prevent excessive hemorrhage.

In order that autotomy may occur it is necessary that the peripheral portion of
the limb should offer a greater resistance than the traction of the extensor muscle is

‘able to overcome, allowing the traction of the muscle to be equivalent to a weight of
250 grams. Ordinarily the sides of the carapace, the hard parts of an adjoining leg
or the clutch of an enemy afford the necessary resistance.

If the compound—second and third—joint of the cheliped of the lobster be examined
a fine hair line is seen leading from the small spur next to the articular facet on the
under side, round the anterior border to the upper side of the joint. It then bends
forward and abruptly backward, crossing the small proximal end of the joint, to near its
pointof departure (x, cuts12,13, plate D). There are incomplete grooves in front of this
line (cut 12, a, b,) and a more oblique one behind it (cut 12, ¢). On the upper side of
the second joint of the small walking legs of the lobster a delicate hair line is also seen,
which turns abruptly forward at the anterior border of the appendage and joins the
arthrodial membrane. This groove looks as if it might mark the plane of rupture in

102 BULLETIN OF THE UNITED STATES FISH COMMISSION.

a part of the joint, but it does not correspond to the intersegmental groove (cuts
13, 14, x) of the cheliped.

I have never observed the casting of a claw at any time before the fourth larval
stage. Autotomy seems to be occasionally practiced at this period, and in the fifth
and following stages it is common. ‘This is illustrated by the history of larva No.
23, table 34. When this lobster in the fourth stage was placed under observation, July
25, it was 13 mm. long and had lost both its large chelipeds and its right fifth and left
fourth pereiopods. When, fifteen days later, August 9, it molted to the fifth stage
(length, 15 mm.), the large left cheliped (figs. 92, 96, plate 33) and the fourth and fifth
walking legs were regenerated; the right cheliped appeared as a rudimentary stump.
Hight days later, August 21, it had molted to the sixth stage (17 mm. long), when its
large right cheliped appeared regenerated. The animal was placed in a flat glass dish,
and in disturbing it, upon changing the water, it shot off its large left cheliped again
and died two days after.

In the first larva there is a free articulation between the second and third joints of
the great chelipeds (fig. 66, plate 30), and there is no true fusion of the segments until
after the fifth stage. In the fourth stage the articulation is distinct, as represented
in cut 15. ‘This not only shows that the plane of rupture in the large chelipeds

Cur 15.—Part of first cheliped of fourth larva, showing the base of the limb and distinct articulation
between the second and third joints.

a-a), plane of section shown in fig. 169, plate 43; br, podobranchia; 2, articulation between second and third joints,
corresponding to plane of fracture in adult appendage; y, articular process in second joint; 1-4, segments of limb. Drawn
from molted shell.

corresponds to what was formerly a free articulation, but also that this autotomy is a
comparatively recent acquisition. It may have been acquired independently in the
Macrura and Brachyura. Autotomy of a pronounced character occurs only in limbs
where fusion of two neighboring joints has been effected, and was probably produced
as a result of natural selection while the fusion was taking place.

The habit of “‘casting a claw” being of a purely reflex character, and therefore not
subject to the will of the animal, there is needed only the proper stimulus to call it into
play. Unintentional experiments in autotomy have often been made by tethering a
lobster or crab by its large claws. The animal, of course, escapes, leaving only its
members behind. When lobsters are drawn out of the water by the claws, or when a
claw is pinched by another lobster, or while they are handled in packing, especially
for the winter market, they often “cast a claw;” and the transportation of lobsters
at this season is said to be attended with considerable loss in consequence. The old
custom of plugging lobsters, which consisted in driving a wooden wedge between the

THE AMERICAN LOBSTER. : 103

joints of the claws, to prevent them from injuring each other, has been generally
abandoned. Mutilated lobsters are now often placed in pounds, where they are
allowed to repair their injuries.

One has only to examine a lot of freshly captured lobsters to be assured of how
common the practice of casting the claw is. “Out of a hundred specimens,” says
Rathbun (755), “collected for natural-history purposes in Narragansett Bay in 1880,
fully 25 per cent had lost a claw each, and a few both claws.” Ina total of 725 lobsters
captured at Woods Hole in December and January, 1893-94, 54 or 7 per cent had
thrown off one or both claws.

It is often stated that lobsters sometimes cast their claws during thunder storms,
but until some proof of the truth of this statement is afforded it must be regarded as
a fable. One of the earliest versions of this idea which I have seen is that of Travis
(191), who wrote to Pennant in 1777 that—

Lobsters fear thunder, and are apt to cast their claws on a great clap. Iam told they will do
the same on firing a great gun, and that when men-of-war meet a lobster boat a jocular threat is
used, that if the master does not sell them good lobsters they will salute him.

Since autotomy is the result of a reflex nervous impulse, and has been acquired
by the animal as a means of defense, we should expect to find that the reflex center
would always be aroused into activity by stimuli coming through the nerves of the
limb, as is always the case in experiment, and not through a higher center like the
brain. When an animal is frightened by loud noises it is impelled to flee, and it would
manifestly be of no advantage to the animal to immediately drop its legs.

REGENERATION OF APPENDAGES.

The regeneration of lost limbs in crustacea has been studied by Réaumur (767)
Goodsir (80), Chantran (38, 40), and Brook (26).

Réaumur’s general account of the process in the crayfish is one of the best which
has been written. He quotes Du Tertre (55), who had “made similar observations
on the crabs of Guadeloupe, of which he has given a very curious history.” Réaumur
began his experiments on the seacoast, but the sea broke and carried away his boxes
or filled them with sand. He then experimented with crayfishes with more success.
He says:

I took several of them, from which I broke off a leg; placed them in one of the covered boats
which the fishermen call ‘ Boutiques,” in which they keep fish alive. As I did not allow them any
food, I had reason to suppose that a reproduction would occur in them like that which I had attempted
to prove. My expectation was not in vain. At the end of some months I saw, and this without
surprise, since I had expected it—I saw, I say, new legs, which took the place of the old ones, which I
had removed; except in size they were exactly like them; they had the same form in all their parts,
the same joints, the same movements. A kind of regeneration like this hardly less excites our envy
than our imagination; if, in the place of a lost leg or arm, another would grow out again, one would
be more willing to adopt the profession of the soldier.

He noticed that the time necessary for the production of new legs was indetermi-
nate, depending upon a variety of conditions:

These limbs arise and grow more or less rapidly, like plants, according as the season is more or
less favorable; the warmer days are those which hasten the more their formation and growth.

Sometimes new legs sprout out in three weeks; sometiines not until after six, and
when the legs are broken off in winter they do not grow again until summer.

104 BULLETIN OF THE UNITED STATES FISH COMMISSION.

Réaumur cut off the “tails” of crayfishes in various places, but there was never
any reproduction of these parts, and the animals invariably died after a few days. It
sometimes happens that a lobster loses a part of its ‘‘tail,” and the accident probably
results fatally in most cases, but not always, according to the statement of Mr. Thomas
Barton, who is employed at the lobster pound at Vinal Haven, Maine. He says that
in the winter of 1892-93 he caught several lobsters with the tail-fan and the last one
or two joints of the “tail” gone, apparently bitten off. There was a scar where the
wound had healed, but no sign of a regenerated tail.

Chantran (38) says of the crayfish that the antenne are regenerated in the period
between two successive molts, while three molts are required to restore the other
appendages. In the first year of life, seventy days, according to this observer, are
necessary for the generation of new limbs. The adult female requires 3 to 4 years,
the male 14 to 2 years to repair its limbs, and we are told that the adult male molts
twice and the female but once in the year.

Chantran has also some interesting notes on the regeneration of the eyes in the
crayfish (40). This process takes place more or less normally and rapidly according
to the age of the animal. When the eyes are cut off in October, at the end of the
season of molting, there is no new growth apparent until the following May. At that
time a series of molts is begun, and by July, nine months after excision, the eyes are
regenerated. If the eyes are operated on in the molting season, the regenerative
processes are disturbed. In his experiments about one-half of the optic peduncle
was cut away; with total excision of the peduncle the eye was never regenerated.

Goodsir (80) explains the production of new limbs from the basipodite in the
following way:

A small glandular like body exists at this spot in each of the limbs, which supplies the germs of
future legs. This body completely fills up the cavity of the shell ror the extent of about half an inch
in length. The microscopic structure of this glandular-like body is very peculiar, consisting of a
great number of large nucleated cells, which are interspersed throughout a fibro-gelatinous mass. A
single branch of each of the great vessels, accompanied by a branch of nerve, runs througha small
foramen near the center of this body, but there is no vestige either of muscle or tendon, the attach-
ments of which are at each extremity. In fact, this body is perfectly defined and can be turned out
of the shell without being much injured. When the limb is thrown off the blood vessels and nerve
retract, thus leaving a small cavity in the new-made surface. [See the account given by Fredericq. ]
It is from this cavity that the germ of the future leg springs, and it is first seen as a nucleated cell.

These statements, some of which—as the existence of a glandular body and the
origin of the limb from a nucleated cell—are entirely erroneous, will be discussed
hereafter (see pp. 107, 108).

REGENERATION OF LARGE CHELIPEDS.

The regeneration of the large chelipeds in the fourth and fifth larval stages is
essentially the same as in the adults. The external changes are illustrated by figs.
176, 182, and may be described as follows: At the moment the limb is broken off blood
immediately oozes out and coagulates, forming a dense 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, fig. 176, plate 44. This papilla continues to
grow, independently of the molting process, though covered with a cuticular mem-
brane, until a miniature appendage is formed. The papilla lengthens, and gradually
the constrictions which mark the future joints of the new limb make their appear-
ance. At first colorless, the new appendage becomes bright, transparent red, with

THE AMERICAN LOBSTER. 105

bluish pigment at the constrictions of the joints (fig.182). In this stage the limb is
surrounded by a thickening cuticle and soon ceases to increase until after the next
molt. It may, according to Brook, attain a length in young lobsters of 14 to 14 inches.
If autotomy occurs just after a molt, the appendage will reach a much greater size
than if it happens a short time before. 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.

Two stages in the regeneration of the large cheliped of the larva already referred
to (No. 25, table 34) are illustrated in figs. 92, 96. After a period of 15 days, during
which time two molts had occurred, this limb had become completely regenerated. It
was reproduced in 12 days after the emergence of the papillary bud.

A larva in the fifth stage, length 15 mm., was placed under observation July 28,
when the first right cheliped was clipped off. On August 12, 15 days after the injury,
the animal molted and the cheliped appeared restored. The lobster was now 17 min.
long. The length of the sixth joint—propodus—of this rudiment at the time of the
molt was 2 imm., while the length of the same joint of the limb after ecdysis was
44 mm., and the length of the corresponding joint of the unimpaired limb was 5 min.
In this case the new limb had been developed during a single molting period to nearly
its normal size.

A similar result was obtained in the following experiment: A fifth larva, length
15 millimeters, was placed under observation on July 28, and the first right cheliped
was clipped. The right antennary flagellum had been previously cropped close to the
stalk, from which a new bud was growing; 6 days later, on August 3, the sprouting
antennary flagellum was coiled, and a very small bud represented the right cheliped.
August 12, 15 days after the first observation, the flagellum of the second antenna on
the right side was nearly normal in appearance and size. The rudiment of the right
cheliped was segmented, and about 3 mm.long. This larva molted on or near August
15, or 18 days after mutilation, to the sixth stage, when it attained the length of 18 mm.
The right cheliped was regenerated, but, as in the other case, 1t was somewhat smaller
than the other. The measurements are as follows:

Regenerated right first cheliped: Length of propodus, 5 mm.; greatest width, 1.3 mm,
Unimpaired left first cheliped: Length of propodus, 6 mm.; greatest width, 1.5 mm.

On the one hand, the large cheliped of the young lobster may be regenerated in
from 15 to 18 days, and after a single ecdysis, and on the other it may require a
month’s time, during which the animal has molted twice.

The time required for the renewal of a limb thus depends upon the time at which
an injury occurs with reference to the molt, and also upon the physiological condition
of the animal. 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 sixth joint (propodus or large joint of claw in cheliped), it is
usually cast off at the plane of fracture.

REGENERATION OF ANTENNA AND OTHER APPENDAGES.
The antenne are very liable to injury, particularly the delicate, sensitive fiagella.

Autotomy does not occur in these appendages, so far as is known, but regeneration
may take place at any articulation in the flagellum or stalk.

106 BULLETIN OF THE UNITED STATES FISH COMMISSION.

In the young the flagellum of the second antenna may be completely restored
without a molt taking place; in the adult one molt at least appears to be necessary
for complete restoration. In the fifth stage already mentioned, the antennary flagellum
was restored in about fifteen days. The flagellum appears first as a papilla or bud,
which becomes sickle-shaped and finally coiled (figs. 100, 179).

Fig. 100 is from the molted shell of a lobster 18 mm. long (No. 34, table 34). It lost
itsright antennary flagellum in molting, July 25, and molted again in two weeks’ time.
The drawing shows the condition which the regenerating appendage had reached in
the interval between the molts. After the last molt it was completely restored. This
figure illustrates the stage which the appendage usually reaches before its complete
renewal with the next molt. The flagellum then resembles a small, spirally coiled,
red-wax taper. In fig. 179 this appendage is being renewed from the first joint.

The cuticle of the limbs in process of restoration must be elastic or capable of
considerable distension, although the limit of this distensibility is, in most cases, soon
reached.

In the isopod crustacea the antenne are regenerated in a somewhat different
manner. In the case of the large Ligea oceanica, illustrated in figs. 180, 181, plate 44,
the rent is repaired, and the new bud does not grow out from the stump, but coils
up within it. The cuticular wall of the stump serves as a sort of brood chamber for
the growing part, until it is set free at the next molt.

Autotomy often occurs in the second to fifth pereiopods, but is much feebler than
in the large chelipeds. Two stages in the regeneration of these appendages are shown
in figs. 175, 178. The fourth pereiopod of a fourth larva, drawn from the molted skin,
is illustrated in fig. 99, plate 33.

Réaumur (167) was one of the first to attempt to give a philosophical explanation
of regeneration in crustacea. He says:

We may suppose that these little limbs which we see grow out were each inclosed in a little egg,
and that when a limb was broken off the same juices which nourished this part were used to
develop and bring to the birth the little germ of a limb inclosed in this egg. Moreover, according to
this theory, we should have to suppose that there was no spot in a leg of the crayfish where there
was not an egg which incloses another limb or, what is more marvellous still, a part of a limb like
that near the point where the egg is situated at the end of the limb; in short, at any point in the leg
which you may name there must be one of these eggs, which contains another part of the limb, The
eggs which are at the origin of each claw, for example, would contain only a claw: but one egg
would not be sufficient, since if a new leg is cut off another comes.

How many times this process could be repeated without exhausting the supply
of “eggs” he did not determine, but Spallanzani, according to Weismann, ‘observed
in the case of a young Triton, that the four limbs and tail when they were cut off
grew again six times in the space of three summer months.” (The Germ-Plasm, p.
120.) Réaumur believed that each new limb must contain an infinite number of eggs,
and in conclusion says:

It would seem that the reproduction of the legs of the crayfishes is a matter where we can scarcely

hope to see clearly ; besides its peculiar difficulties, it has all those which envelop the generation of
the foetus, ae

It is over eighty years since these words were written, and the solution of the
problem of regeneration seems to some as far away as ever. The new limb is not
formed from a definite cell or cell-mass recognizable before the time of injury, but
from a budding growth very much as in the embryo.

THE AMERICAN LOBSTER. 107

The power of regenerating a lost part varies in both vertebrates and invertebrates
in direet proportion to the physiological importance of the part, as Weismann has
clearly shown. Just asthe enemies of the lizard seize it by its long trailing tail, so the
lobster is almost invariably caught by a claw, and the life of the animal is often saved
in either case by the breaking off of the member. The plane of fracture in the limb,
as in the large cheliped of the lobster and in the five pairs of pereiopods of the crab, is
a secondary structure which coincides with the plane of articulation of two coalesced
joints, yet Leydig has shown, according to Weismann, that the tail of the lizard is
specially adapted for breaking off, “the bodies of the caudal vertebre from the
seventh onward being provided with a special plane of fracture, so that they easily
break into two transversely.” (The Germ-Plasm, p. 116.) The regenerative power
is probably a secondary characteristic which has been acquired by natural selection,
for the good of the species, while autotomy is a much more recent acquisition. As
Weismann says, ‘‘ there is no such thing as a general power of regeneration” among
animals as with crystals, but ‘‘in each kind of animal this power is graduated according
to the need of regeneration in the part under consideration.”

Weismann rejects the idea of a spiritus rector, or external directing agency, and
assumes that the nisus formativus is situated in the “idioplasm” of the cell, and “that
each cell capable of regeneration contains an accessory idioplasm, consisting of the
determinants of the parts which can be regenerated by it in addition to its primary
idioplasm.” He furthermore infers that the general capacity of all the parts for regen-
eration may have been acquired by natural selection in the lower and simpler forms,
and that it is gradually decreased in the course of phylogeny in correspondence with
the increase in complexity of organization.

Weismann attempts, in a very ingenious way, to harmonize the facts of regenera-
tion in animal embryos with the “‘mosaic theory” of development of Roux, but, as E. B.
Wilson (206) remarks, the two fundamental postulates of this hypothesis, ‘‘namely,
qualitative nuclear division and accessory latent idioplasm, are purely imaginary.”
The theory of Roux and Weismann has its counterpart in the view advocated by
Whitman (204), that ‘‘in the development of the germ, in the repair of injured parts,
and in the regeneration of lost parts the organism as.a whole controls the formative
processes going on in each part.”

While no final explanation of the process of regeneration can now be given, and
the idea of a formative power is, as Whitman says, one of profound mystery, the
solution of which appears to lie as far beyond our grasp to-day as at any time in the
past, yet we arein a better position to-day, if not to give answers to these questions, at
least to point out the probable direction in which they should be sought.

I shall consider the question of regeneration again in connection with the origin
and perpetuation of deformities in the lobster.

INTERNAL CHANGES IN REGENERATION.

The histogenesis of the new limb is not easy to understand, although it can be
followed without much difficulty after the papilla stage.

I am unable to find any trace of “ glandular-like” bodies such as Goodsir described
(80) as furnishing germs of the new limb. On the contrary, the new limb appears to
arise mainly by growth of the connective tissue cells already present in the stump.

After the blood has clotted over the wound and has produced a hard crust, the
cuticular cells, in response to the stimulus thus received, grow over the wound and

108 BULLETIN OF THE UNITED STATES FISH COMMISSION.

produce a new cuticle which has a certain degree of elasticity. My material was insuf-
ficient to trace with certainty the origin of the reticulated tissue which soon appears
under the new skin.

A minute papilla grows out, having the general structure shown in fig.175. It is
a spongy network of fibers, containing the potential elements of muscles, nerves, con-
nective tissue, and blood vessels. Blood flows in an irregular system of large and
small sinuses. The epidermis of the new skin, which is relatively much thinner than
the old, is composed of a single stratum of very tall, slender cells, the chitinogenous
epithelium, and of an elastic cuticula. The epidermis of the papilla is thus structurally
similar to that which covers all parts of the body when a new shell is being formed
under the old. (See p. 77.)

As the papilla grows out the fibrous tissue becomes gradually differentiated into
the muscles, blood vessels, and nerves (fig. 172), as in an embryo, and constrictions in the
cuticle arise, which mark with absolute precision the limitation of the future joints.
The cuticle at this stage appears to be destitute of hairs, but it contains pores. In
the stump at the base of the appendage a great mass of large oval bodies is seen.
These appear as thin solid dises, and when compressed break like starch grains (fig.
121, pl. 36). They represent connective tissue cells in a certain stage of metamorphosis,
and in all probability contain glycogen, which furnishes material for the growth of the
epidermis—that is, of the chitinogenous cells and the shell which they secrete. (See
p. 78.) They seem to be the same structures which Leydig has described in the
integument of crabs, under the name of lime concretions (Kalkconcremente), and
which Hoeck calls “ Krystall Plattchen” (121-122). Mayer (137) has also fignred and
described what are probably similar bodies in the indurated shell of certain swellings
which are found in the large claws of the male Heterograpsus lucasii. These he desig-
nates as ‘amyl-like chitinous inclusions.”

In the lobster these bodies stain very diffusely, and sometimes a central figure,
possibly the impression or remains of the original nucleus, may be detected. The
histogenesis of these structures and the changes which they undergo have apparently
never been studied. Their origin is clearly demonstrated by fig. 122, plate 36, from
a preparation of the maxilliped. It is evident that the large granular mass is the
product of the parent mesoblastic cell, the protoplasm of which is reduced to a thin
enveloping shell.

Fig. 169 represents one of a series of sections cut in a longitudinal plane through
the first three joints of the right large cheliped of the lobster (sixth stage, length 18
mm.), the history of which has been already given (p. 105). The appendage of this
larva had been cut off July 28, and had grown to nearly its full size by August 17,
when the animal was preserved. Since autotomy occurs in the very young animal as
well as in the adult, we should be able to determine from this specimen whether
there is any preformed organ or store of embryonic cells for the supply of the new
limb at this time. The examination of serial sections through this part of the limb
reveals nothing but normal tissue cells. Embryonic cells may be present but are
not discernible. The opening between the basipodite and ischiopodite is reduced to
a narrow passage by the ingrowth of cuticular cells, to form ectodermic pillars like
those seen in the carapace of the embryo. The several tissues are bathed in blood,
which is here confined to no definite channels. Some circumscription of the passage
leading from the second to the third joint is thus necessary.

Chapter V.—LARGE LOBSTERS.
THE GREATEST SIZE ATTAINED BY THE LOBSTER.

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,' 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 are copied
by Gesner (75), 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
which weigh from 20 to 25 pounds 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 to look upon the mam-
moth lobster simply as a favorite of nature, who is larger than his fellows because he
is their senior; good luck has never deserted him until at last he is stranded on the
beach or becomes entangled in some fisherman’s gear.

Gesner gives a very poor figure of a lobster, but a very good drawing of the large
crushing-claw of one which he had preserved in his collection on account of its great
size. The length of this claw is 8? inches, and its breadth at the junction of the
dactyl about 4 inches, so that it must have belonged to a lobster which weighed not
far from 8 pounds.

Pontoppidans (152) relates a fable, which is repeated by Herbst (88) and others, of
the Stérjer, or lobsters of huge size which fishermen reported having seen in Utvaer
in the Bay of Erien, Norway. One of these was so large and terrible that no one dared
to attack it, and it measured between its claws at least a fathom. This, says Herbst,
probably belongs with the Kracken, the natural products of Norwegian superstition.

Boeck says that he had seen the claw’ of a lobster which must have been about
18 inches long, and Sir John Graham Dalyell (50), according to Boeck, tells us, in The
Powers of the Creator, published in 1827, that he had seen a joint of the left claw of
a lobster which measured 9 inches in length. It does not follow, however, as Boeck
infers, that ‘the whole claw” must have measured 18 to 24 inches, and the whole
animal 3 to 4 feet.”

The European lobster of to-day seldom attains so great size as the American
species, and its average weight is considerably less. Buckland (28) gives the following
account of large lobsters from the British Islands:

The Skye and Orkney lobsters are probably the largest in the British Islands. At St. Mawes we

heard of two lobsters, one 10 pounds and the other 9} pounds; and at Durgan and Sennen of one of
13 pounds. A large lobster was caught in a large earthenware pot at Gosport in 1870 which weighed

' Historia de Gentibus Septentrionalibus, Rome, 1555.
>The word claw is here inaccurately used to mean the entire claw-bearing limb (cheliped).
109

110 BULLETIN OF THE UNITED STATES FISH COMMISSION.

8 pounds 10 ounces, In May, 1875, a lobster, weight 12 pounds, was found at Saints Bay, Guernsey.
I find a record of a Jobster exhibited at Billingsgate July 30, 1842, which measured 2 feet 54 inches;
the size of the body was 16 inches; the claws measured upward of 14 inches. In August, 1873, a lobster
weighing 11} pounds, caught in Guernsey. was exhibited by Messrs. Grove, of Bond street. In July,
1874, a lobster, weight 74 pounds, was caught on the Fife Banks of the Forth. The lobsters from
the Lizard ground are one-third heavier than those in Falmouth Bay, but crabs are smaller.

The largest lobsters that have come under my individual notice are, first, a lobster weighing t04
pounds, sent me from Tenby and now in my museum; secondly, a lobster presented to me by John
Byatt, of Messrs. Winder’s, Haymarket, measuring 8 inches in the barrel [that is shell of back or
carapace], the total length being 19§ inches and the weight 9% pounds. In the York Museum there is
a magnificent specimen of a lobster, of which the following are the dimensions: Barrel, 94 inches;
tip of beak to tail, 19} inches;' left claw, the crusher, length 10} inches; right claw, cutting, length
103 inches; left claw at widest part, 5inches. This was an American specimen.

Another very large lobster we came across in our inquiry was a grand specimen which we exam-
ined in the house of Mr. Scovell, at Hamble, near Southampton. The following are the dimensions:
Length of barrel to tip of horn, 9} inches; length of tail turned under the body, 12 inches; total
length, 2 feet, all but three-quarters of an inch Right claw, 193 inches? long; girth, 12} inches;
weight when killed, 14 pounds. This lobster, Mr. Scovell informs me, was caught in a trammel net on
the coast of Cornwall.

Fourteen pounds is the greatest weight recorded in the notes just quoted, and
European lobsters of this size are undoubtedly very rare.

In the museum of the Academy of Natural Sciences of Philadelphia there is
preserved a large lobster, Astacus vulgaris, for the particulars concerning which I am
indebted to the kindness of Professor Ryder. Unfortunately it is not known where
or when it was captured, nor what its living weight was; but from the measurements
given below (table 29, No. 1 a) I conclude that it weighed from 21 to 22 pounds. If
these measurements are compared with those given in table 30, No. 1, it will become
evident that this specimen could not have weighed less than 20, and not more than 23
pounds. This specimen has been carefully examined by Professor Ryder, who writes
that there is no doubt of its belonging to the European species; that it was normal in
every respect, and that the skeleton is in an admirable state of preservation.

TABLE 29,

| _| No. 2 a.—Male;
Smee: 10 pounds; cap-
obtained from | eared OA CLIO!
“aii orway some
Measurements. Europes eDT es ‘time between 1850
museum of the and nee pre-
University of pee me Bereerh
Pennsylvania. Norway. »
Total length, rostrum to end of telson (not including hairs) ----.inches. - 19.4 18. 73
Length of carapace (rostrum to posterior margin).-..-.----- eedOeree| 9. 29 8.58
Large forceps:
ength of propodus (straight measurement). ---..-...-------- do.... 13.1 10. 23
Greatest breadth of propodus.....-------/.-:--.-----2--.2----- doze 6.8 4.32
Girthotpropodus 2-2) s2-eeseeeeee sere reese ee oseeeeeereerr dowees 16.8 10. 62
Small forceps:
Mens throfspropodus! => meee see a= soe ee ene secon aeeaee dower 12.4 10. 03
Breadthsof4propodUs- ass eee ace eee eee ease reece dower 4.8 3.30
Girthvorpropodus sss. e-ese seer seer hese caste eee doss-- 10.15 8.07

! The claws of this specimen were considerably undersized (compare tables 29 and 30).

2 This is intended for the measurement of the entire right claw-bearing limb or cheliped; by
“total length” is probably meant, as above, the distance measured from the tips of the extended
chelipeds to the end of the tail.

THE AMERICAN LOBSTER. 111

In speaking of the size attained by the European lobster, Sars says:

It is a remarkable fact that the lobsters on our southern coast never get as large as those farther
north. I have never seen an unusually large specimen among the many lobsters which I examined at
the different fishing stations. The lobsters which are occasionally caught farther north are generally
much larger, and to judge from their appearance much older. At Floré [ once saw a lobster which
was not much smaller than the immense specimen in the Bergen Museum. This specimen, as far as I
remember, comes from a still more northerly point of our western coast. (276.)

Iam able to give some comparative measurements of the ‘immense specimen”
to which Sars refers in the passage just quoted, through the kindness of my friend,
Dr. Einar Lénnberg, of the University of Upsala. If the length of this lobster and
the measurements of its large claws (No. 2 a, table 29) are compared with the other
specimen (No. 1 a), and with lobster No. 7, table 30, we shall see that in all prob-
ability the Bergen specimen did not weigh above 10 pounds. It is nearly an inch
longer than lobster No. 7, which weighed after preservation in alcohol a little less
than 10 pounds. On the other hand, the claws of this American lobster are larger
than those of the Norwegian specimen, and the claws constitute in old lobsters more
than one-half the weight of the entire animal. (See table 51 a.) The latter probably
weighed when alive not over 10 pounds.

In reference to my questions about the Bergen lobster, Dr. Lénnberg writes:

The specimen is now dry, and, as we never weigh any lobsters in our country, the weight is not
recorded.

He says the date of capture is doubtful, but it was probably between 1850 and 1865,

It has been an accepted belief that the American lobster attains a greater size
than its European counterpart, but it seems to be a fact that the maximum size of
each species is nearly the same. The lobster fishery is much older in Europe than in
this country, and the average size has there been long reduced to a minimum by
overfishing. At the time when Sars’s paper was written (about twenty years ago)
it would not have occurred to one familiar with the American species to look upon a
10-pound lobster as an ‘‘immense specimen,” though at present there are comparatively
few of this size which find their way to markets. In fact the same gradual falling off
in size, due to the same cause, has been experienced in recent years on the coast of
Maine and in the Maritime Provinces. It is probable, however, that the American
lobster is stockier than the European, and that length for length the American species
will weigh the more.

Buckland (29) speaks of a ‘‘ breed” of lobsters caught at Bognor which are always
small. They are called “chicken lobsters,” and it takes 14 to 20 to weigh a pound.
This merely illustrates how the size may be kept down by the persistency of fishermen.

Rathbun (155), in speaking of the occurrence of large lobsters in American
waters, Says:

A dealer at New Haven states that twenty years ago 12 to 16 pound lobsters were common, but
during the past ten years a lobster weighing 10 pounds has been rarely seen. A Boston dealer writes
that during the past season (1880) he had received and sold lobsters weighing from 12 to 15 pounds
each. ~ * * A specimen taken at Boothbay, Maine, and said to weigh between 30 and 40 pounds,
had such claws that the meat from one of them was equal to that of an ordinary-sized lobster.

I have examined and carefully measured a lobster taken at Boothbay which is
probably the one here referred to, and will describe it presently. The actual weight
of this lobster was probably not over 22 pounds.

A lobster ‘‘shipped from Eastport in 1875” is said to have weighed 19 pounds
and to have ‘measured 3 feet 5 inches in length (measurement from tips of extended

112 BULLETIN OF THE UNITED STATES FISH COMMISSION.

claws to end of tail), the claws being 18 inches long and 8 inches across.” (155.) If
the weight is given correctly, the measurements are certainly at fault, as I shall
presently show.

There can be nothing in literature more unreliable than accounts of the size and
weights of animals, gathered at random. The first estimate is often a guess, which
immediately acquires an air of accuracy by being expressed in figures. It does not
usually get into print until it has been rolled over many tongues, and during the
process it increases in size like the snowball which is rolled along the ground. But it
undoubtedly comes hardest for a man who has a large lobster for sale to resist
temptation. In describing a few very large lobsters I shall therefore limit myself to
those which I have actually seen and measured or weighed.

I will now give the history of a lobster which came into my possession in August,
1893.' It is probably one of the largest lobsters ever taken on the Atlantic coast.
Its history has been carefully authenticated, and I have obtained some excellent
photographs of it, which are reproduced in plates 1 and 2. This mammoth specimen
was captured in Penobscot Bay, southeast of Moose Point, in line with Brigadier
Island, near Belfast, Maine, May 6, 1891, in about 34 fathoms of water, by Mr. John
Condon. Its capture was accidental, since it was brought to the surface on the end
of a lobster pot, the “tail” of the lobster resting in the funnel of the trap, while the
huge claws hung down at the sides. The animal, attracted by the bait, had doubtless
been making fruitiess attempts to enter the trap. A dealer in fish at Belfast soon came
into the possession of this lobster while it was still alive. The shell was then very
dark in color, almost black on the upper surface, and supported a number of prosperous
colonies of marine animals. The cominon barnacle (Balanus balanoides) was growing
on the shell of the back and also on the upper surface of the crushing-claw, near the
joint of the thumb or dactyl, where it may be seen in the plate. Several species
of mollusks, particularly the common mussel (Mytilus edulis), were fixed to various
parts of the shell, and hydroids (Pennaria or Eudendrium) were flourishing at the
articulations of some of the legs. The presence of these messmates pointed to a
rather sluggish habit of life, which the animal may have possessed. The entire
upper surface of the shell and both the upper and lower surfaces of the claws are
scarred, scraped, and gouged like the side of a cliff over which a glacier has passed,
and present a graphic record of the struggle for life which this animal had so long
and so successfully fought.

When laid on its back the lobster could move but little, but when in its normal
position it would crawl over the floor, and if worried with a stick it seized it savagely
and crushed it with its claws. It was weighed on a Fairbanks scale in the presence
of anumber of people. Its living weight was found to be a little over 23 pounds.”

This lobster was finally killed by boiling in the usual way, the membranes being
first cut at the articulations to let out the blood and admit the water. It was after-
wards placed in a large kettle of water to which a bushel of salt was added, and was
boiled in this brine for more than an hour.’ After it was boiled, the meat of the

'This lobster is now preserved, in excellent condition, in the museum of Adelbert College,
Cleveland, Ohio.

2? When I first saw this lobster I was assured that the animal was not weighed until after it had
been boiled. Allowing a shrinkage of 20 per cent in boiling, I estimated the living weight to have
been about 28 pounds. (See 99.) The first statement was not true. I have since ascertained that the
facts are as given above.

3Old-shell lobsters are said to shrink 20 per cent and new-shell lobsters 25 per cent in weight
after boiling.

ay

re

THE AMERICAN LOBSTER. 1b}

“tail” was of a pink color and very tough. The skeleton was perfectly preserved
by removing the muscles of the abdomen and the “tomally ” or “liver,” and some of
the other organs of the body. This lobster was a male, and it is a noticeable fact that
all very large lobsters which I have records of or have examined belong to the male
sex. I have never heard of a female lobster which exceeded 183 pounds being caught.

The total length of this lobster, whose history I have just given, is only 20 inches
(measured, as in all cases, from the end of the spine or rostrum to the end of the tail-
fan), but would have been nearly 21 inches had the rostrum been perfect. The body
seems surprisingly short for so powerful an animal, and it is in fact in the large claws
that the greater part of its weight and strength resides. This may be seen by a
comparison of the plates (see also table 31 a), and may be possibly 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 size of the claws. Thus Hhrenbaum (61) mentions a
lobster 42.2 em.long, which showed an increase in length of scarcely 1 mm. on molting
The length of the crushing-claw of the Belfast lobster is nearly 14 inches, and its
greatest girth is 164 inches. It was probably powerful enough to crush a man’s arm
at the wrist.

TABLE 30.

General descriptions: No. 1 was a male, 23 pounds, captured at Belfast, Maine, May 6,1891. No.2 wasa male,
20 to 22 pounds, captured at Boothbay, Maine, about 1856. No.3 was a male, 20 to 22 pounds, captured at Salem,
Massachusetts, in 1850. No. 4, 23 to 25 pounds, was captured at Gloucester, Massachusetts. No. 5 was a male, 20
to 22 pounds, captured on the Delaware coast. No. 6 was a male, 20 to 22 pounds, captured at Lubec. Maine, Sep-
tember, 1892. No.7 was a male, 9% pounds, in alcohol.

|
Measurements in inches. No.1. | No. 2. | No. 3. | No. 4. | No.5. | No. 6. | No. 7.
|
Total length, rostrum to end of telson (not including
VATS) PE sw eect cae Oa cae eee meee anes
Carapace:
ene thio RTOs tu Meaeee sence eae see eee eee
Length of carapace : 8355 {ite ay. ee
Length of carapace, including rostrum..-.-....-.-..--- 818 93 hte eS ccbed|pocesans 94 83
Distance from cervical groove to posterior edge of
CER AS) cosa pe nodaeacaanacoosancosdecoboceoassosnes
(CUCBLESUDAGE GUN San eéccscaasud saccosencasoaReSeEned| bop seeae| Sassoced bacaacod ls sedoaod bonoaned Gdoss oes lboeenc a.
Breadth between spines, near base of rostrum.--.--- 1} 135 Pe es eteerass 13 Ue eespeices
Breadth between spines, near base of second an-
LON ese ese Seo mec coe sec Scccas an oae tecaies 225 2 24) Neeetococi 22 De Il 2 Scenes
Girth of carapace behind cervical groove ..-...----- 143 134 BGP WBcnasedd Rodenmed MT Nopeencas
Pleon:
Length of second segment (including facet). ....--..|---...-- I bebeaded | beaccose 2 IC} oncebee
Breadth of second segment ene cmnonouge sneceacesesee 44 346 BE \leosccmne (0%, |Hoodenod basoae a.
Girth of second segment (spine to spine).--..-----.. 88 82 Bae Recieve ae CF. badcssacl BaSbose
Length of sixth segment (including facet) 13 MFR Beocabod bends sod beousece a 2 ee
Greatest width of sixth RES sSodGns5snosaconses 4 GV eesesese| beosaccal: couched bontos 34s so sane
Length of telson (not including Sete) s-sae oscars 1+3 25 QR |e njecetee pees 24 22
Bread timoptelsonatbasoeeeee sen -ren soe s eee eene aes 25 27 25! |. SSS eee 24 23
Antenne : |
Length of stalk of first antenna | 133 1g § | |s eeieeee Seereccr 10] beeen |
Length Olgbasalyseementeerececr res sehen sees see 4 nit? | Pemceeod bossoboa| basemen i eseccrerets
Breadth of basal ROO NON Meme eee Saree ee see 4 CRS AP SO eASaea peteGooed toredood Oi eee |
Length of ey © tal Ren aa aco mR CEM Se it | lepeeeead |aasen codbossccce|Hcoosson ay | bcos |
Breadth of GYy.0S ballot mows. ho ees so te Ga |Poscosed scapoped benoueod beoneoad Hoconsad tusenees
Length of stalk of second antenna =e 2% 13 JES | beeusmas|haaceose LGa| Seems!
ihength of'exopodite! (scale) --222-22.-22-2.---- 2... Ke rs Wy |paoonoodfonosicor Fe llooaaneae
Greates towid Giseee seep see meee (eee ania nook 4 5 Mis |lbaodedadbsacHose ¥ lessees |
Pereiopods: | H |
Large forceps (crushing-claw)— | |
Length of propodus (straight measurement) --.--- 13% 123 124 13 134 12 102 |
Greatest breadth of propodus at level with articu- |
Latloniwa GheGdachy leeeemee neers eens cee css se. 1g 6 64 | 4g gL 92 54 |
Girth of propodus just behind articulation of | = 4
dacty Beene eee ere ener ace eecesc ae | 164 15} Sy Nae aS | 15 134
* Body nearly straight. t Body somewhat bent.

F.C. B. 1895—8,

114 BULLETIN OF THE UNITED STATES FISH COMMISSION.

TABLE 30—Continued.

|
Measurements in inches. No. 1. | No. 2. No. 3. | No. 4. | No. 5. | No. 6. | No. 7.

Pereiopods—Continued
Length of dactyl.-....... aia(eta\a a\a'alsiala{a-alelajsia\aleie(e sine
Greatest breadth of dactyl ieee ee eo eres teiae
Greatest girth of dactyl....--.--.------------.----
| Length of. carpus (oninner margin, not including
| proximal. spine). .2oc ce eneee ee oes
| Greatest breadth of carpus.-..-.---------
| Greatest girth of carpus...-.....-.--
Length of meros (outer border)
Greatest breadth of meros-.-..----------- 5 4
Small forceps— | |
Length of propodus (from tip to spine near prox- | |
Imaliond)= eset eee eee eee ee ee eeerea seas 31 5 al
Breadthzotspropodusssssec sciceae cess
Girthlofspropodusssesscsemss aseseseeeees
engthiofidactyterrrcts secs sel
Greatest breadth of dactyl bce
Greatest girth of dactyl...-.-..-.------.----------
Length of carpus (on inner margin, not including
PLOXimalapine) eee eee eee eee eee He | Sortee ye ete 4 33
Greatest breadth of carpus..-..-...-.-- Q%
Greatest girth of carpus...-----.-- ---- 83,
Length of meros (outer border) aad
Greatest breadth of meros.....------------------- 25
Second and fifth pereiopods: |
Length of propodus, second pereiopod...-----.---
Breadth at articulation of dactyl.....---.--..--.--
en othiotidactylass--eeeeerr ast eee eceene ease cee
| Breadth of dactyl (at articulation).......--.......
| Greatest length of carpus--.-.-.--.-.-----.-.-.-..
| Breadthiotecarpusterseece see eee ee sete eee ee
Length of dactyl, fifth pereiopod....-.--.-.---..-.
Breadth of dactyl es ee See ees A eee
ene thiotspropodusseeseeeeecseca-stere eee ceae
Breadth of propodus (distal extremity) ...---..--.
Breadth of propodus (proximal extremity) .-------
eng theoficarpus=eemser tees ceer -mmemen etter
Breadthiofgcarpus ses. seseese cesar meas sens
Pleopods:
Length of first pleopod. -
Length of distal segment. ....--..-- Bdoo
Greatest breadth of distal Seomentseeecece-eeeerre
Length of stalk of second pleopod ABSronbaaosdsacé
Breadth of stalk of second pleopod.......--..-..-
Length of exopodite -.....-.--...-.-.-.-.--.------
Breadth of CxXOpoditemss. reer oeo se ee eee ore.
Length of exopodite, sixth pleopod (from angle
between spines of protopodite) ......-...-....-.
Greatest breadth of exopodite at hinge .-..-..-.---
Length of endopodite of sixth pleopod bosceodcascc
Greatest breadth of endopodite of sixth pleopod. .

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The detailed measurements of this animal are given in table 30, No.1, where they
may be compared with those of the small lobster, seen on plate 2, and with those of
the large specimens which I have recorded above.

The large Boothbay lobster, which has already been referred to (p. 16), is
reported to have weighed as much as 40 pounds. I was told that it tipped a seale
which weighed up to 25 pounds, and would have weighed somewhat more. Its meas-
urement, however (table 30, No. 2), proves it to have weighed less than the Belfast
specimen, and a comparison of its length and the dimensions of its claws with the
large European lobster (No. 1 a, table 29) show that it could have exceeded this in
weight very slightly, if at all. Its true living weight was probably between 20 and 22
pounds. The shell of this lobster was cleaned by placing it in an ant-hill, and it is now
in a bad state of preservation. The claws are furrowed, pitted, and scarred, and the
carapace is scratched, as is apt to be the case with large old-shell lobsters.

In the museum of the Peabody Academy of Science at Salem, Massachusetts, there
is a perfect specimen of a lobster (No. 3, table 30), said to have been taken at Salem

THE AMERICAN LOBSTER. 115

in 1850, and to have weighed, when alive, 25 pounds. The body is a little longer than
the two first mentioned, but it is also slenderer, and the large claws, which count so
much in the weight of this animal, are, upon the whole, smaller and weigh less. The
greater length of the Salem specimen is due largely to the long, perfect rostrum.
The large claws correspond closely in size with those of the Boothbay lobster, and we
may be almost certain that its living weight did not exceed 22 pounds.

A lobster but little under the Salem specimen in size is in the possession of Mr.
George R. Batson. of Campobello Island, New Brunswick. This lobster weighed,
when alive, according to the somewhat wavering memory of the man who weighed it,
245 pounds. The measurements fail to corroborate this statement. (No. 6, table 30.)
The dimensions of the large claws and the girth of the carapace prove conclusively
that it weighed less than 23 pounds, the authenticated weight of the Belfast lobster
(No.1, table 30). It was captured in a hoop pot, a few of which are said to be still in
use, in South Bay, near Lubec, Maine, in 15 fathoms of water, September, 1892. This
lobster is a very shapely and perfect specimen. It had a hard shell, and showed
great activity when alive.

In the museum of the Peabody Academy of Science there is also the right large
claw of a lobster marked, ‘From a lobster weighing 39 pounds; from Moses H. Shaw,
Gloucester.” This is said to have been in the museum for over fifty years. Meas-
urements of this claw (No. 4, table 30), supposing the animal to have been normally
developed, show that it could have been but littie larger than the Belfast specimen.
The only available comparisons lie between the large claw and the fifth joint the
only parts preserved. A full-sized drawing of this huge claw is produced on plate
15. The crushing claw of the Belfast lobster was nearly an inch longer and much
broader than the specimen figured, but less by one inch in girth. The claws of these
two animals must thus have been of nearly equal weight, and I think it a safe con-
clusion that the Gloucester giant did not weigh above 25 pounds. The shell of the
claw was very light for so large an animal, weighing only 162 ounces, including the
fifth joint. (See chapter III, pp. 82, 83.)

In the museum of the Smithsonian Institution there are fragments of the skeleton
of a lobster which was captured with hook and line on the coast of Delaware, and is
said to have weighed over 25 pounds. Measurements of these parts show that its
weight was probably somewhat less, certainly not much over 22 pounds. (No. 5,
table 27.) The shell of the large claw of this lobster weighs 15 pounds.

In 1863 a large lobster was caught on a hand line at Bald Head Sands, near
Small Point, Maine, which I was assured by a fisherman weighed 88 pounds. I
afterwards had the opportunity of examining the large crushing-claw, all that has
been preserved of this lobster, at the market house of Mr. Lewis McDonald, Portland,
Maine. The claw is 124 inches long, has a breadth of 64 inches, and a girth of 154
inches just behind the terminal joint. It was thus of about the same size as the
crushing-claw of the Salem lobster (No. 3, table 30), and the animal probably did not
exceed 22 pounds in entire weight. I mention this as an example of how the weight
of the lobster, though dead, increases with the lapse of time.

There may be seen at the St. Nicholas Hotel in Boston, Massachusetts, the skeleton
of a male lobster said to have weighed 35 to 40 pounds. It was captured off Province-
town, in August, 1894. When I examined this specimen, June 25, 1895, it was
mounted in a glass case in a very perfect state of preservation. Though not allowed
to take careful measurements, I could see that its weight had been greatly exag-

116 BULLETIN OF THE UNITED STATES FISH COMMISSION.

gerated. The total length of the body, measured from the rostral spine to the end of
the tail-fan, when the tail was naturally articulated with the thorax, was not far from
20 inches, and not over 21 inches. The length of the large crushing-claw is from 12
to 13 inches. The cutting-claw is relatively smaller than in any of the large lobsters
which I have examined, and it seems fairly certain that the living weight of the
animal could not have much exceeded 20 pounds.

1 am indebted to the kindness of Professor Leslie A. Lee for the measurements of
the large crushing-claw of a lobster which is preserved in the museum of Bowdoin
College, Maine. It was taken from an animal which came from Cape Breton, which
is said to have weighed 33 pounds 11 ounces. The length of this claw is 13,4; inches,
its breadth 6% inches, and its girth (measured just behind the first joint) is 16 inches.
In this case the weight is specifically given, yet it is certainly erroneous.' If normally
formed, this animal probably did not weigh over 23 pounds. I base this opinion upon
the fact that the Belfast lobster (No. 1, table 30) has a somewhat larger crushing-claw,
is normally formed, has a hard shell, and therefore could not, in all probability, have
weighed less and may have weighed more than the specimen from Cape Breton.

In the museum of Yale University there is preserved the large crushing-claw of
a lobster, which is said to have weighed 39 pounds.? The length of the claw is 12;
inches, the greatest width 6.9 inches, and the greatest girth 163 inches. It is shorter
by half an inch than the Cape Breton specimen, and but little larger in circumference.
The length of the crushing chela falls short of the Belfast lobster (No. 1, table 30) by
one inch. Its weight probably did not much exceed 23 pounds, if at all.

In the collections of the Smithsonian Institution there is a lobster which weighed,
after preservation in alcohol, 9 pounds 14 ounces (No. 7, table 30). The cutting-claw
on the right side was undersized. A few measurements of this specimen are given
for purposes of comparison. There is far less difference between some of these and
corresponding measurements of larger lobsters than one might expect. Thus the
telson in this case has the same dimensions as in lobster No. 6 (table 30), which
weighed more than twice as much.

I was informed by Mr. F. W. Collins that a male lobster which weighed nearly
25 pounds was taken on a trawl below Monro [sland, 5 miles east of Rockland, Maine,
in the summer of 1890. The large claw is said to have measured 16 inches in girth.

I heard through Mr. Vinal Edwards of a lobster, said to have weighed 27 pounds,
which was caught off Bretou Reef, Newport, Rhode Island, in June, 1894. This was
taken by accident, one of its claws having been entangled in a lobster-pot, in 10 to 12
fathoms of water. It was a male, and its shell was freely sprinkled with barnacles.‘

I will add a few notes on the occurrence of large lobsters, which I gathered on the
coast of Maine, in August and September, 1893. I give them upon the testimony of
others, but believe them trustworthy.

Mr. J. W. Savage stated that he received from the region of Eastport, Maine, in

Professor Lee writes as follows concerning this specimen: ‘‘The large lobster’s claw in our
museum was obtained many years ago in Cape Breton. It came into our possession in 1881. The
weight of this animal is not well authenticated on our records.”

*I am indebted to Prof. A. E. Verrill for the opportunity of examining this specimen. The
inscription upon it, which is almost illegible, is as follows: ‘Boston, Mass., March, 1823; 39 lbs.”

‘The weight of this lobster was kindly determined by Mr. James E. Benedict of the Smithsonian
Institution.

41 was unable to obtain any direct information about this lobster, or to verify its weight, which
I do not consider authentic, :

THE AMERICAN LOBSTER. 117

¢

June, 1893, a large male lobster which weighed 20 pounds. In the same lot was one
weighing 16 pounds.

In May, 1892, Mr. N. F. Trefethen obtained a lobster from the vicinity of East-
port, Maine, which weighed 154 pounds. He weighed it himself, and sent it to market.
It had a very hard shell and had lost its smaller claw; if it had been perfect it
would have weighed considerably more.

In Angust, 1891, according to Mr. F. W. Collins, a lobster (sex undetermined)
was taken at Blue Hill Falls, 40 miles east of Rockland, which weighed 184 pounds,
and in November, 1892, a perfect female lobster was taken at Green Island, Maine,
which weighed 18 pounds. This outer island 1s noted forits fine lobster fishing. Mr.
Collins states that in August, 1891, he had fifty lobsters at one time in his establish-
ment which would weigh from 10 to 183 pounds. About half of these came from
Castine and the remainder from Blue Hill Falls, Maine. <All of these were “new shell
lobsters ”—that is, they had shed that year, probably in July.

Mr. Thomas Garrett, who was one of three men who first engaged in lobster
fishing at Vinal Haven, Maine, over forty years ago, and has been engaged in this
pursuit most of the time since, says that he has taken a great many lobsters which
would weigh from 15 to 20 pounds. He says that a perfect male lobster weighing 30
pounds! was taken in a hoop-net in Golden Cove, in Vinal Haven Harbor, in about the
year 1858, and that in 1887 a lobster was caught in the basin (near the site of the
present lobster pound on Vinal Haven Island) which weighed 11 pounds and had only
one Jarge claw.

The mouth of the Skillings River is said to have furnished large lobsters in
plenty in the fall of 1888. It was very common to take lobsters there weighing 15
pounds. The place had not been previously fished with regularity, but it soon became
the resort of fishermen and the lobsters were rapidly reduced in numbers and size.

Fishermen in Rockland, Maine, have gaffed lobsters in the harbor in the past two
years weighing from 8 to 9 pounds. I heard of a large lobster which was caught on a
trawl, the hook catching in a joint of the shell, in June, 1892, on White Island grounds,
near Vinal Haven. It was said to have weighed over 20 pounds.

Mr. F. W. Collins informs me that he received at Rockland, in 1893, a larger
number of lobsters than usual measuring about 15 inches in length and weighing
about 5 pounds.

These notes furnish evidence, if any were needed, that very large lobsters, weigh-
ing 20 pounds or more, are even now occasionally taken, but I have never obtained
any reliable evidence that lobsters weighing over 25 pounds have ever been caught.
Where lobsters are said to have attained a greater weight, measurements of the parts
of the skeleton which have been preserved invariably prove that the figures have
been exaggerated. I do not maintain that the American lobster does not reach a
greater weight than 25 pounds, but that I have been unable, up to the present time,
to discover any well-authenticated evidence that this is the case.

Many points on the coast of Maine and the Maritime Provinces still furnish large
lobsters weighing 10 pounds or more, but not in any considerable number, and lobsters
of 5 pounds weight are frequently common; yet it is at the same time true that the
size of the lobster has been declining for many years, until the average weight has, in
most places, fallen below 2 pounds.

'The weight of this large lobster may have been unintentionally exaggerated. One can hardly
avoid such an inference from the evidence already given.

118 BULLETIN OF THE UNITED STATES FISH COMMISSION.

THE RELATION OF WEIGHT TO LENGTH.

inde

The weights and lengths! of 2,657 lobsters captured at Woods Hole under the
conditions already described (p. 25) are recorded in table 31. The weight does not
bear a constant relation to the length, but is very variable owing to the loss of the
appendages, particularly the large claw-bearing legs. These alone constitute from one
quarter to one-half the entire weight of the animal, and probably in the Belfast lobster
(plate 1), and in all giants of similar size, the weight of the large chelipeds is more
than two-thirds that of the entire body (see table 31a). The lost limbs are regenerated,
as we have seen, but never completely so without the intervention of one or more
molts, so that a lobster with an undersized claw is a common occurrence.

The weight also is subject to great variation in consequence of the molt, when a
dense heavy armor or cuticle 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. Very few soft lobsters, however, were taken during the period of these obser-
vations, only about 3 per cent (see table 23), so we may ascribe the great variations
Shown in the table below chiefly to disparity in the size of the large claws. This is
particularly noticeable in smaller individuals, as in the 9-inch lobsters, where out of
170 males the smallest weighed only 10 ounces and the largest three times as much.

TABLE 31.—Kelation between the lengths and weights of male and female lobsters, taken in Woods Hole
Harbor, December to June, 1893-94.

7 | | Total Average
p | | No.of | Average |Extremes; No.of | Average Extremes; ee eTAZe |
Length | Ne: of | Average Extremes) femaies weight of of weight) females weight of lof weight te weight
in ma.e8 | weight of weight) without | females joffemales,) with females joffemales ands elithemales
inches. Great j of males. | of males | eggs ex- | without | without | eggs ex: with with famalesil ts aaa
( | amined. | eggs. eggs. | amined.| eggs. CLES.) Crammed lttonialest
| | =
oz.
6 7 7.29
64 il 8
63 UN ay
63 5 7. 60
7 92] 10.49
7 i 2@
if 14| 10.36
is 113) | eee lIG3
73 29} 12.66
8 308 15. 21
8% i |] a
81 73 | 15.27 |
8} 258 16. 50
84 53 | 17.28
9 336 | 18.79
93 1} eG
93 70! 19.63
94 317 | 20.84
93 56 22. 52
10 351 | 24.08
103 28)
104 133 25. 76
104 182 27. 66
108 1| 26
103 36) 27.19
11 93 32. 22
114 21| 34.52
114 41 36.37
iy 4; 35.25
12 23 42.91
12 1 50
19 it 45.45
123 4570
13 8 49. 75
133 1 68
14 1 88
143 3 68
15— 3 69. 33
geosocat OAS I eeecocion

‘The length of the lobster is measured from the apex of the rostral spine to the end of the
telson, not including the terminal fringe of hairs.

THE AMERICAN LOBSTER. 119

The fact that the male is heavier than the female of the same length is very clearly
brought out by the observations recorded above. In passing the eye down the
columns to the left only three cases will be discovered where this is not true, namely,
in the 6, 7, and 8 inch lobsters. The difference here in favor of the females, where a
sufficient number of observations were made to entitle them to much confidence, is
only a question of fractions of an ounce in average weights. After passing the 8-inch
limit the balance is in favor of the male. The 10-inch males are about half an ounce
heavier than the females of the same length. From this stage the excess in favor of
the male becomes very narked. The 11-inch male exceeds the female of the same
length by a full quarter of a pound. In the lobster 124 inches long there is a greater
difference in favor of the male, 74 ounces in the cases cited in the table.

It is evident from the facts here recorded 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 development of the large
claws. :

The average weight of females without and with eggs recorded in columns 6 and
9 of table 51 brings to the surface a rather unexpected fact, namely, that females with
spawn are in a poorer condition or weigh relatively less than females without. In
one-third of the cases here 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. Turning to table 16, we find that the
average quantity of eggs borne by a 10-inch lobster is 1.73 fiuid 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 22.135 ounces, as compared with
23.76 ounces, the average weight of non-egg-bearing females of this size. There is a
difference of 1.63 ounces in favor of the female without eggs. In the case of the
94-inch lobsters, where 169 in all and 24 bearing eggs were examined, the average
weight of the spawners is 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 possibie condition for food.” (28, p. XVI. See p. 64.)

In the last column of table 31 the average weights of lobsters corresponding to
definite lengths are given. A lobster of the minimum length at which it can be legally
sold, 105 inches, weighs on the average 1? pounds, while a 12-inch lobster attains a
weight of 2 pounds 11 ounces, and a lobster 15 inches long weighs from 4 to 44 pounds,
and probably more in some cases.

Lobster No. 7, table 30, 173 inches long, weighed nearly 10 pounds (though in this
case the cutting-claw was undersized), and the mammoth specimens recorded in this
table, weighing from 20 to 25 pounds, varied only from 20 to 21? inches in length
(pp. 113-116).

In the early part of this chapter I mentioned the fact that the disparity in weight
between lobsters of the same length was due largely to the difference in the size of
the large claws. This is illustrated by the following table, which is compiled from the
observations made by Vinal N. Edwards.

120 BULLETIN OF THE UNITED STATES FISH COMMISSION.

TABLE 3la.— Variation in the weights of lobsters with and without the great claws.

No. of Weight NV eight
Length in Sex lobsters | with large | Variation es cheli Variation
inches. sk exam- | chelipeds, | in weight. |“ peds “| in weight.
ined. | in ounces. Aeoumcae
730) Mialeseeaes=: 1 1B); |'ae eae eases 10M eeseee eee 2
73 Fem ue ....- 1 1G} pee apGashaor UD | Recmobtrcoad
82 Female --.-- 3 13 to 15 2 11 0
82 Maletts22s.- 1 fis | HoeeeeasEses 1A | epee maressa
Sie | Maloeee anaes 1 sles | eee eke LO Calle a ee Sas
8 Female -..-- 1 1G a he aetioodeaie Lies eee ee
83 Malesearen 1 WY \eiseaSasoodod BU}. | Weencsecoote
93 Maleoss-2 4 6 22 to 31 9 15 to 17 2
93 Female --..-. 2 23 to 24 1 15 to 16 1
10 Malet ress 1 Pest Ne nsaerpecibete HVT | reseeyarmPetet= =otete
10 Female -.. -- 3 24 to 27 3 17 to 18 1
11 Mialeezeence 1 Ce Weememoodcas 22Ma leer cee
11 Female ...-- 1 39e he cseeccesee PP POT

Chapter VI—ENEMIES OF THE LOBSTER.
ANIMALS WHICH PREY UPON THE LOBSTER.

The adult lobster, whether with eggs attached to the body or not, is the prey of
numerous 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.

A fisherman at Beal Island, West Jonesport, Maine, stated that he had caught
cod on trawls 10 to 15 miles from shore with lobsters 4 to 6 inches long in their
stomachs. Cod were also caught at Grand Manan, in summer, in 20 fathoms of
water, by Mr. J. W. Fisher, of Eastport, with very small lobsters,’ 1 to 2 inches long,
in their stomachs. Lobsters an inch long have also been taken from the stomachs of
codfish on the shores of Prince Edward Island (209, p. 232), and soft lobsters 3 to 8
inches long have also been found in the stomachs of these fish taken in deep water
off shore.

The observations of Mr. Vinal N. Edwards are quoted by Mr. Rathbun (156, p. 782)
to show the great destruction of lobsters in the Edgartown district, Marthas Vine-
yard. Out of hundreds of cod caught about No Man’s Land and examined by Mr.
Edwards, nearly every fish ‘contained one or more young lobsters, and in many cases
the stomachs were almost entirely filled with them.” So great did the destruction
wrought upon the lobster by the cod impress one fisherman (156, p. 728) that he thought
the cod a greater enemy than the lobstermen, and said: ‘I have caught one hundred
cod in one day that I knew had the amount of one thousand lobsters and shadows in
their entrails.”

' These young lobsters were identified by Professor Baird.

THE AMERICAN LOBSTER. 121

The cod has an equally bad reputation among English fishermen. Frank Buck-
land says (28, pp. 14, 15):

Among the animate enemies the principal enemy [of the lobsters] I believe are cod. A witness at
Burghead stated that codfish are great enemies to lobsters; he hardly ever opens acod without finding
young lobsters in the stomach, particularly in February and March. He has seen cod throwing up
lobsters on the deck of a vessel, as many as five or six lobsters in one cod. These lobsters would be
3 ord inches in length or even smaller. Cod eat lobsters all the season. In the spring and in January,
February, and March there are many cod about. Skates and congers, and codling and haddock also
eat crabs and lobsters.

On July 16, 1894, Dr. J. I. Peck showed me the “tail” of a soft lobster which he
had taken from the stomach of the weakfish or squeteague (Cynoscion regale). The
lobster had been out of its shell but a few hours when it was snapped up by this fish.

Verrill (196) records the finding of lobsters in the following fish: Dusky shark
(Hulamia obscura), Woods Hole, in July and August; dogtish (Justelus canis), Woods
Hole, in August; sand shark (Hugomphodus littoralis), Woods Hole, July and August;
peaked-nose skate (Raia levis), Menemsha, July; long-tailed stingray (Myliobatis fre-
minvillet), Vineyard Sound, July; rabbit-fish (Chilomycterus geometricus), Woods Hole,
July; striped bass (Roccus lineatus), Woods Hole, August, 1871; tautog (Tautoga onitis),
“two caught July 83 and 15 contained small lobsters.” ;

Mr. Mosher, who had prepared striped bass for market for upward of thirty
years, said:

Striped bass do not feed upon live menhaden, but upon crabs and lobsters. * “~ * Ihave

always observed that bass fishing was best where lobsters and crabs were most plentiful. (Bull.
U.S. F. C., vol. 11, p. 410.)

Small lobsters are probably to some extent the prey of sea-roving birds, such as
the gulls and terns, but in regard to this nothing is known. According to Boeck
(20, pp. 227-228), the Norwegian lobster is sometimes attacked by crows. His account
is as follows:

An interesting scene may be witnessed near Bukken6, north of Stavanger, where an Englishman
has constructed a large pond between some small islands for keeping live lobsters. Whenever the
pond becomes too full of lobsters, so that they do not find sufficient food, they leave the water and
crawl about, seeking to reach the sea, but during their wanderings they fall an easy prey to large
numbers of crows hovering round, which take them in their claws, fly high up, and let the unfor-
tunate lobster drop down on the rocks, where their shells are broken, so that the crows can eat them
in comfort. The crows are not easily scared away, but.show a remarkable degree of sense, only
flying away when anyone approaches with firearms, and later they carry on their depredations in the
early morning, when they have less to fear.

That lobsters ever leave the water and attempt to crawl upon the land can not be
credited, and it is likely that this story passed through several hands before reaching
its present form. Herbst (88) says that the lobsters have a great enemy in the Stein-
beisser. ! .

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 eight
or ten weeks of their life? From the time of hatching up to the sixth stage the
young lobster swims at the surface and becomes an easy prey to all surface-feeding

‘It is uncertain what fish is here meant. The name is applied to the fresh-water genera Cobitis
and Lota.

122 BULLETIN OF THE UNITED STATES FISH COMMISSION.

fish, some of which, like the menhaden,! roam about in vast schools, straining the
water as effectively as the towing net. During this period the lobster measures
from one-third to two-thirds 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.’ (For the further consideration of this subject
see pp. 187-189.)

PARASITES, MESSMATES, AND DISEASES OF THE LOBSTER.

One of the two parasites known to infest the lobster is a trematode (Stichoco-
tyle nethropis). This was first described by Cunningham, who found it in the intestine
of the Norwegian lobster. It has recently been discovered in the American lobster
by Dr. Nickerson, to whom I am indebted for the following particulars. The larva
of this singular parasite, which is from 3 to 7 millimeters long, is found sometimes to
the number of 70 or more embedded in the mucous coat of the intestine about the
cecum. It is relatively rare, hardly more than 2 per cent of the lobsters which Dr.
Nickerson examined being infested by it. Its position at the hinder end of the
alimentary tract seems to argue that it comes in by way of the anus rather than
through the mouth. Its final host is probably some species of fish which feeds upon
the lobster, but the adult trematode is unknown. It may prove to be of a different
species from the larva discovered by Cunningham.

The only other strict parasite which the lobster is known to possess is the large
Gregarine (G. gigantea), which was discovered in the intestine of the European lobster
by Van Beneden. (194)

In 1853 Van Beneden (69) called attention to a small green worm which he found
on the eggs of the lobster, and which he supposed was a larva of Serpula. Later,
in 1858, he concluded that the animal was not a larva, but a fully developed indi-
vidual, which he called Histriobdella homari, placing it among the Hirudinee (69).
Foettinger, a later student of this form (69), proposes to change its name to Histrio-
drilus benedeni, and concludes that is is an Enteroceelian, allied to Polygordius. It
is not a parasite in the strict sense.

Although parasites are rare, 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 convenient angles of the shell and joints, small
tunicates sometimes becoming attached firmly to the under side of the shell between
the legs. Tube-forming annelids, lace-like bryozoa, form incrustations in various
parts, and red, brown, and green algve often decorate the antenne 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.

‘Regarding the menhaden as an enemy of the larval lobster, I have consulted with my friend,
Professor J. I. Peck, who has made a very careful study of the habits of these remarkable fish. He
writes as follows: ‘ I have never found lobster larve in the stomachs of menhaden, and yet it must be
remembered that the localities whence my material was nearly all secured were brackish-water inlets.
Copepods in all stages of growth are abundant and shrimp of the smallest size were common at New
Bedford, but in the material trom Buzzards Bay I have never seen lobster larve.” He thinks that
the evidence can not be conclusive until menhaden are examined which have fed both day and night
in localities which abound in lobsters.

THE AMERICAN LOBSTER. 3

At the lobster pound in Vinal Haven, Maine, which I visited on August 26, 1893,
I examined a number of lobsters whose bodies and free appendages supported a
Surprisingly varied flora. A hard-shelled female which I took out of the mud in
very shallow water was decorated with alge in a very striking fashion upon the upper
part of the body, the big claws, and antenne. The long whip-like “feelers” were
weighed down with fronds of the brown laminaria, or devil’s apron, as shown in
fig. 118, plate 36. The common green lettuce (Ulva latuca) was sprinkled freely over
various parts, and barnacles had gained also a foothold upon the shell. A frond of
laminaria, which was fixed to the side of the abdomen, was 7 inches long and 2 to 3
inches in width. Besides the larger fronds, there was a matted undergrowth upon
the antenne, composed of several species of alge and attached fungi. One of the
men employed at this pound said that he had taken hard-shell lobsters with “kelp”
2 feet long growing upon the shell.

A lobster now in the Peabody Museum of Yale University was incrusted with
Nullipores, when it was captured in Nantucket in April, 1880. This specimen was
a male and weighed about 10 pounds.

Mussels sometimes glue themselves in extraordinary numbers to the under sides
of the bodies of living lobsters, in places where the animal is unable to scratch them
off. A good illustration of this may be seen in the museum of the Peabody Academy
of Science at Salem, Massachusetts, where there is a male hard-shelled lobster about
12 inches long with fifty or more shells of the common Mytilus edulis attached to its
body. The shells of some of these bivalves are 14 inches long. They have wedged
themselves between the bases of the thoracic legs, the plates of the tail-fan, and have
fastened themselves even to the head between the antenne and about the eyes.

It is not uncommon to find the barnacle (Balanus batanoides), as we have already
seen, attached to the shell of both very old and relatively young lobsters (fig. 1, plate
1). ‘The large Belfast lobster carried about with it several species of mollusks, as
well as barnacles and hydroids.

On July 15, 1894, I found a lobster which had been kept for several days, or perhaps
for a longer time, in a floating car, with one of its eyes completely hooded by a colony
of bryozoa. When set free, the eye appeared perfectly normal.

The messmates of the young lobster consist chiefly of fungi (of which bacteria are
the most characteristic) and of diatoms. Young lobsters captured at sea seem to be
peculiarly free from foreign matterof every kind, but when the young of almost any of
the crustacea are confined they soon become clogged with solid organic or inorganic
floating particles and bacteria with which such material is invariably associated. The
hairs which garnish the body and appendages of crustacean larve serve to gather
up and hold solid particles from the water, so that one of the first considerations in
the artificial rearing of crustacea is to give them as clean a water supply as possible.

I have seen larve in the fifth stage of development literally covered with a mass
of diatoms (Tabelaria, Navicula, ete.) like those found in the brown sediment at the
bottom of the jar in which they lived and in the undigested food contained in their
stomachs. Old lobsters, in which the molting period has become very infrequent,
are commonly the worst sufferers from enemies of this kind, but the physiological
condition of the animal is, as we have seen, the most important consideration.

The crayfish, which isdevoured eagerly by numerous species of fish in fresh-water
lakes and rivers, both in this country and in Europe, is infested by Trematode worms,
which become encysted in the tissues of the animal. Distomum nodulosum has been

124 BULLETIN OF THE UNITED STATES FISH COMMISSION.

described from Cambarus propinquus by Wright and Linton, and Ward (198) has found
in the same crustacean still another species, Distoma opacum. ‘+The cysts occupied
the space in the cephalothorax above the heart and sexual organs.”

The “ tomally” or liver of the lobster is free, so far as is known, from parasites
of all kinds, yet this is not the case with all the decapod crustacea. In June, 1885,
while dissecting the southern shrimp (Peneus setiferus), I found numerous stages in the
development of a cestode worm, Tetrarhynchus (species undetermined), in the liver of
this prawn. The youngest were oval, about ;+5 inch in long diameter; the oldest
larve measured ;'s inch; they had a round, flattened body, an anterior segment or
neck, with four well-developed proboscides, and a “tail” of about equal length, and
unsegmented. Two pairs of bright red pigment spots were borne on the upper ante-
rior part of the body.

DISEASES OF THE LOBSTER.

There are no specific diseases to which lobsters are subject, so far as known, yet
they sometimes die off so rapidly as to lead one to suspect that they may have fallen
a prey to some contagious disease.

Mr. N. F. Trefethen, of Portland, Maine, tik owns a lobster pound in South
Bristol, 35 miles east of Portland, resins the following experience: In May, 1893,
he placed 100,000 lobsters in this pound, 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 were 12
to 13 feet of water in this pound at flood tide and not Jess than 9 feet at low water.
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 depression covered with a membrane. This was probably a sore resulting from a
wound which the animal had received in the back, and which had failed to heal. A
similar case is mentioned by Rathbun (155).

Chapter VI.L—THE TEGUMENTAL GLANDS.

The shell of the lobster, as has been seen already (pp. 77, 78), is not a solid armor,
but is everywhere perforated by capillary canals which open by minute pores at the
surface. One set of these ducts is called the hair pores. These lie immediately
beneath the hairs or set of the shell. The other set constitutes the ducts of the
tegumental glands.!

The tegumental glands are very generally found in the decapod crustacea, and
they are more widely distributed over the body of the individual than almost any
other organ. Nevertheless their structure has never been accurately determined, and
almost nothing is known of their function. They lie in the dermis or in the connective
tissue and adjoining muscles immediately below the cuticular epithelium. They are
opaque, subspherical or oblong, not usually over } mm. in longest diameter, and
each communicates with the exterior by means of a capillary duct, the entire length
of which—not including the part which traverses the enticle—is probably not more
than ;}, mm. (cuts 4 and 5, pl. A, and fig. 208, pl. 49) and its diameter only 4; mm.
These minute organs are scattered all over the body and appendages; they are
particularly abundant about the mouth and in the esophagus, and Vitzou has found
them in the walls of the intestine of Palinurus (197). As he remarks, ‘‘one may
study these organs indifferently in a macruran or brachyuran, for they have the same
structure in both.”

GENERAL STRUCTURE OF THE TEGUMENTAL GLAND.

The tegumental gland, wherever found, whether in the appendages or beneath the
skin of the body proper, has the structure shown in cut 5. It consists of a central
reticulate body or rosette, the exact nature of which is unknown. In the midst
of this there is a small cavity, which is continued into a short capillary duct. The
latter perforates the cuticle and thus places the organ in direct communication
with the exterior. Grouped about the rosette is a cluster of gland cells of various
shapes and sizes. Each has a broad base and tapering central end, which is united to a
process of the rosette. Hach organ is supplied with a nerve and contains an eccen-
tric, bipolar cell, which resembles a ganglionic cell. One of the processes of the
latter joins the rosette, while the other unites with the nerve. Rarely two such cells
appear in the same organ. The duct and nerve usually issue from the gland together,
the former possessing apparently, for at least a part of its course, a thin sheath.
Each organ is usually surrounded with a delicate capsule, probably of connective
tissue, though it is not always possible to detect such an envelope.

I have seen no branching of ducts, each organ opening independently at the
surface, and I have not succeeded in determining with any degree of satisfaction the
relation which the nerve fibers bear to the gland cells.

1 Similar structures have been called dermal glands, salivary glands, and cement glands. While it is
probable that they originate in the epidermis, it may be better to classify them under the generic
term of tegumental glands.

In the work of this chapter, relating to histology and technique, I wish to acknowledge my

indebtedness to Professors Patten and Watase for valuable suggestions,
125

126 BULLETIN OF THE UNITED STATES FISH COMMISSION.

What is the function of these organs which are distributed so widely over the
surface of the body? It has been found that glands of a similar character play a part
in excretion. (Text-book of Comparative Anatomy, Lang, part 1, p. 330.) Those found
in the esophagus were regarded as salivary glands until the embarrassing fact was
discovered that they were also found in the walls of the intestine. When occurring
in the swimmerets and ventral abdominal region of the female these organs have been
considered responsible for the liquid glue or chitin-like cement which is poured over
the eggs at ovulation, and have been accordingly called cement glands. It seems
probable that they have such a function, and I shall proceed to describe them in
detail as they occur in the lobster.

THE CEMENT GLANDS.

If we strip off the hard cuticle from the pleopod of a female lobster just before the
eggs are laid (fig. 144, plate 40), we will see thousands of opaque whitish bodies lying
upon the strands of muscular tissue. Each is a gland not more than an eighth of a
millimeter in diameter, and each opens to the exterior by a capillary duet which
pierces the cuticle. The grounds for attributing a cement-producing function to these
organs lie chiefly in their periodical changes coincident with the sexual condition of
the female, and in their absence or restricted occurrence in the pleopods of the male.
Their position upon the swimmerets also favors such a view. We can not look else-
where for such an organ, unless it is to the oviduets, and [ know at present of no
evidence showing that the latter possess this function in the macrura.

CEMENT GLANDS IMMEDIATELY BEFORE OVULATION.

As the time of oviposition draws near, the swimmerets of the female become
more and more opaque, especially along the free margins of their branches. At this
time a milky-white substance can be pressed out, upon removing the cuticle. This is
analogous to what Lereboullet observed in the crayfish (120), and is composed of the
glandular tissue.

At this period the glands have the appearance shown in plate 49, fig. 212. Stained
with the Ehrlich-Biondi anilin mixture the cells have a cloudy, granular appearance.
Their peripheral ends contain a coarser material, which takes a deeper red than the
central parts; the latter appear much lighter, and select and hold some of the green.
The distribution and appearance of the zymogen granules may be compared to that
seen in the pancreas of a well-fed dog, or the resting cells of the submaxillary gland.

An attempt to get a secretion from these giands while in this condition by stim-
ulating the nerve cord by induction currents was not successful, possibly owing to the
fact that these organs had not quite reached the stage of their periodical activity.

THE CEMENT GLAND IMMEDIATELY AFTER OVULATION.

The structure of the exhausted gland, taken shortly after the eggs are laid, is
illustrated by fig. 211, plate 49. If this is compared with fig. 212, which is treated in
the same way, we will find a marked difference in its cytological condition. A very
conspicuous zone of deeply stained zymogen granules surrounds the central rosette,
while the outer parts of the gland cells are poor in zymogen and stain but feebly.
This central darker zone is very variable in breadth, being sometimes reduced to a
thin cirele, involving only the apices of the cells, and is often very sharply marked

THE AMERICAN LOBSTER. 127

off from the rest of the cells. It should be remarked, however, that in two or three
days atter ovalation (external eggs with segmented yolk) there is a striking lack of
uniformity in .he condition of the glands, in many the central zymogen zone being
entirely absent. ‘This may be due to the fact either that some of the glands recover
from exhaustion raster than others, or that they secrete unequally, or that some are
not roused to activity at all.

Fig. 210, plate 49, is from the swimmeret of a female which had probably recently
hatched a brood and was close upon the point of shedding. As may be seen, the
glands are much shrunken in size, the cells transparent and non-granular, as if they
were completely exhausted. This seems to be a perfectly normal case, but whether
it has any significance in respect to the molt I am not able to say.

HISTORICAL SKETCH OF THE CEMENT GLANDS.

Cement glands have been described in numerous species of macrurous crustacea,
but their structure seems to have been imperfectly made out.

Cavolini,! according to Cano (32), maintained that the cement came from the
oviduct, and Rathke (160) regarded the genital organs as the probable source of this
secretion. Erdl (62), in 1843, described three membranes in the egg of the lobster,
and considered the outermost of these to be the secreted product of the oviduct.

Lereboullet (120) barely escaped the discovery of the cement glands of the crayfish
in 1860, but correctly stated that the cement substance came from beneath the skin
of the under side of the abdomen. He had indeed communicated this discovery to the
Natural History Society of Strasbourg in 1852 (published in a note in L’Institut,
in 1853. See ref. 720.) As he says, zoologists had up to this time been almost mute
upon this subject, some expiaining the attachment of the ova to an extension of the
primary egg membrane, others, like Milne Edwards (58), to an albuminous secretion
from the epithelium of the oviduct. Lereboullet described a milky-white matter rich
in fat and nuclei, which is present in the epimeral regions of the abdomen of the
female crayfish at the time of oviposition, but is not found in the male at any period
of the year. He supposed that this substance oozed through pores in the cuticle,
coagulated in the water after fixing the eggs, and that all trace of it subsequently
disappeared until the next reproductive period.

The true source of this secretion was first recognized by Braun (22), who, in
1875, described cement glands in the crayfish. He showed that they consisted of
clusters of cells, which open to the surface of the abdominal appendages by narrow
ducts penetrating the cuticle—a single duct to each cluster. A little later (23) he
figured and described these glands in the six species of decapods. Similar structures
were found in the carapace and esophagus. Cisophageal glands (Speicheldriisen) had
been already seen in several species of crabs, such as Grapsus and Hriphia spinifrons,
and analogous structures were found in the labrum and maxille.

Vitzou, whose work was published in 1882 (197), found glands generally present in
the cesophagus of all the crustacea examined, and they appear in many of his drawings,
but no attempt seems to have been made to study their histology. The csophageal
glands were extremely abundant in the lobster and Palinurus. The ducts are said to

! Memoria sulla generazione dei pesci e dei granchi. Napoli, 1787. I have not had access to this
work, and quote it upon the authority of Cano.

128 BULLETIN OF THE UNITED STATES FISH COMMISSION.

be sometimes united into groups of five or six, and in the intervals small hairs! oceur
upon the surface of the cuticular lining.

Cano (32) devotes considerable attention to this subject, in a paper published in
1891, describing the distribution and structure of the cement glands in a large
number of decapods. Bumpus attributes the ‘“varnish-like layer” which surrounds
the ovum of the lobster after oviposition to a secretion which is supposed to come
from the columnar cells lining the oviducts (30).

In 1893 I gave a short and incomplete account of the cement glands of the
lobster (96). See also 97, note p. 79.

TEGUMENTAL GLANDS IN OTHER PARTS OF THE BODY.

I am not able to map the entire distributi6n of the tegumental glands, but have
found them in many parts. The labrum and metastoma are packed almost full (fig.
208, plate 49). In the latter the ducts open for the most part upon the side next the
mandible. We find them also in the basal stalk (protopodite) and respiratory plates
of the maxille and maxillipeds, where they are already developed in the larval stages
(plate 29, figs. 59, 62), and in the flagella of the antenne.? The skin of the carapace
and abdomen abound in these organs, and they are clustered in large numbers about
the anterior lower margins of the former, just below the cervical groove, where the
surface of the shell is raised into prominences like a grater. The ducts of many of
these glands open into the respiratory cavity. I have also found a few of the organs
in the walls of the seminal receptacle.

In sections through the dorsal posterior surface of the carapace of a lobster nearly
ready to molt I find glands in precisely the same condition as shown in fig. 211, plate
49, where there is an inner deeply staining granular zone. Figure 208, plate 49, rep-
resents an organ from the metastoma, after maceration for three days in Béla Haller
mixture and staining in methylen blue. The duct, running in the nerve bundle,
shows very clearly and can be readily traced to the surface of the gland. By focusing
with care I was able to follow the tubular duct into the central lumen or space, so
characteristic of these organs. The relative number and distribution of glands in
any part can be determined from macerated portions of the shell, as in fig. 170, which
represents the inner surface of the first maxilla.

By maceration and pressure the structure of the gland can be made out in most
of its details. In fig. 203, plate 49, the eccentric “ ganglion” cell (s. ¢.) is seen to give off
two branches, one of which joins the rosette (2), while the other passes into the nerve
bundle, not shown in this drawing. A single gland cell is still joined to a process
of the rosette by its attenuated central end. By rolling this specimen under the
cover slip I was able to confirm the relations here pointed out. In fig. 214, drawn
from a similar preparation, fewer glandular cells are detached, and but one process of
the ‘“‘ganglion” cell is shown. In many instances [ have noticed that the inner ends
of the gland cells have a very refractive, tubular appearance where they join the
central rosette (figs. 209, 213, etc., plate 49), as if they had been snapped off at this
point of delicate union. Figs. 206, 207 show a single gland cell drawn from opposite
sides, from a cement gland of a female with nearly ripe ovaries. Besides the promi-

‘T think it probable that the ducts of the glands really open upon these “hairs,” as they do in
the labrum. (See p. 133.)
>IT have seen them in the outer flagellum only of the first antenna,

THE AMERICAN LOBSTER. 129

nent nucleus at the peripheral end of this cell, there are two other bodies—one near the
tubular neck—which take up the stain like nuclei and are considerably refractive.
From the larger end of the cell (fig. 206) a slender process is given off (compare figs.
201, 204 from the maxill), which suggests a nerve fiber. All that I can say definitely
is that this process is in continuity with the cell, probably with its wall. I did not see
many cases of a similar character.

EXPERIMENTS UPON THE SENSORY AREAS OF THE BODY AND APPENDAGES.

Before discussing the function of the tegumental organs in general, I will record
some experiments which were made to determine how the lobster reacts to stimuli
directed against the dead shell or cuticle.

The lobsters experimented upon were taken from the sea, placed on their backs
on a table, and allowed to remain in this position until quiet. At first they move
their appendages vigorously in trying to right themselves, but soon come to rest. By
sprinkling them with sea water they may be kept fresh for experiment for a consider-
able time.

Various stimuli, such as electricity, heat, weak acetic acid, ammonia gas, clam juice,
were applied to different parts of the body, with a view to ascertain the most sensi-
tive areas where the quickest and most vigorous responses were given.

The degree of sensibility to external stimuli is surprisingly great in many cases,
where the skin of the lobster with its shelly covering seems quite as sensitive as that
of the frog. In other cases, however, the animal is much less responsive, a fact which
we may attribute in some degree to the thickness of the shell.

To sum up the experiments in a general way, all or nearly all the appendages
react strongly to chemical stimuli, and in many cases the surface of the body is
capable of receiving and responding to stimuli of various kinds. If a jet of ammonia
gas 1s injected against the intersegmental membranes or appendages of the “tail,” the
pleopods may be set in very lively motion and violent flexion of the whole abdomen
may follow. Direct the jet upon the anterior swimmerets, and the last three pairs of
walking legs are drawn backward and make scratching movements to remove the
offending object, reminding one of the motions of a ‘‘reflex frog” when its skin is
stimulated in a similar way.

The reaction is more violent when the stimulus is applied to the swimmerets than
when directed against the intersternal membranes. The seminal receptacle is very
sensitive, and when stimulated the walking legs make violent scratching movements
toward it. If the jet of gas is directed along the surface of the walking legs, the
reaction is usually greatest at their tips.

If the extremities of the large chelie, especially the propodus, are touched by the
gas the claw opens and shuts. The first pair of antenne are much more sensitive to
the stimuli than the second pair. If the jet is directed over the region of the mouth,
very violent chewing movements are set up.

If the ammonium vapors be squirted on the dorsal surface of the carapace or
abdomen, a vigorous response is sometimes seen by the immediate movements of the
legs. Both males and females respond to the ammonia stimulus on the abdominal
appendages and intersegmental membranes.

Very similar reactions are obtained if a small piece of blotting paper wet with
weak acetic acid is used. In some cases no response is obtained if the wet paper is

F. C. B. 1895—9

130 BULLETIN OF THE UNITED STATES FISH COMMISSION.

placed on the intersternal membranes of the abdomen, but if laid upon either the inner
sides of the pleura or upon the surfaces of the pleopods the reaction is more marked

If clam juice is placed on the mouth parts, as upon the flattened basal segments
of the second maxille or first pair of maxillipeds, vigorous chewing movements are
immediately begun, and are continued for several minutes. If the stimulus is applied
to one side, the movements are at first restricted to that side only, but eventually, in
some cases, the appendages of the opposite side begin to move also.

If clam juice is dropped upon the swimmerets of the female, a response is usually
forthcoming, and the same is true if this stimulus be applied to the terminal segments
of the walking legs. In the case of the large chele the response may be very slight.
In one instance, where three females and one male were experimented upon, the
abdominal appendages gave no response to clam juice, but the mouth parts were
always extremely sensitive. In this case the pleopods gave a marked reaction when
touched with weak acetic acid.

As arule, the pleopods of the female were more sensitive to the various stimuli’
than those of the male. The abdominal appendages of the body give no reaction
when breathed upon, and show but slight sensitiveness to heat. Weak electrical
currents from an induction coil produce marked responses in the maxille and first
pair of maxillipeds, and if the swimmerets are touched by the electrodes, violent
contractions of the flexor muscles of the abdomen speedily follow.

The preceding experiments would lead us to suppose either that certain areas of
the skin of the body and appendages are very sensitive to a variety of stimuli or
that the skin or parts below it possess special sense-organs. In either case, excepting
electrical stimuli, the organs must be reached by means of the canals which penetrate
the inert cuticle.

Since there are only two possible roads for the entrance of chemical stimuli—the
hair pores and the pores of the glandular ducts—the question is therefore raised
whether the glands possess a subsidiary sensory function. If it could be shown that
the sets of the carapace were not perforated at their tips, it would be certain that
ammonia vapor could not enter them! and extremely probable that the reaction from
this chemical stimulus had its seat in the gland. I believe that these organs do
possess such a subsidiary function, and that this is shown to be the case by a study of
the sensitive labrum, in which hair pores and their corresponding sete are entirely
absent.

The function of the tegumental glands in various parts of the body has been a
subject of much embarrassment. Max Braun (22) thought that the esophageal glands
of the crayfish were salivary organs. Vitzou inclines to acquiesce in this opinion,
but admits that the presence of organs of exactly the same structure in the walls of
the intestine (in Palinurus) is puzzling, to say the least.

Professor Patten (150) has recently discovered certain organs in Limulus to which
he attributes a sensory function. They have essentially the same structure as the
tegumental glands of the decapod crustacea. There occurs in front of the mouth of
Limulus, on the middle line, a wart-like swelling, which Patten regards as the cuticular
portion of an olfactory organ. ‘Directly beneath the ectoderm”, he says, there ‘‘are
a great many—at a rough estimate, from 1,500 to 2,000—clear, flask-shaped sense buds,
each of which is connected by a narrow neck with a cuticular canal.” The structure

1Where the sete are moist it might be possible for ammonium vapor or any other chemical
stimulus to reach the sensory cells by diffusion through the thin chitinous wall of the tubular hair.

THE AMERICAN LOBSTER. 131

of these ‘olfactory buds,” their cuticular canal, gland-like cells, and large eccentric,
in this case multipolar, ganglion, prove conclusively that these organs are essentially
similar to the glands which I have described in the lobster. In discussing this subject
with Professor Patten we have always been mutually agreed upon this point. What
the function of these organs in all cases really is, may well be an open question. In
Limulus the lumen of the organ varied much in appearance, being more sharply
circumscribed in the young than in the adult, where it might be reduced or even absent.
The tubule was sometimes coiled and very brittle. It is “undoubtedly composed of
chitin, for, as with the gustatory tubules, it can still be seen in the cast-off shells of
immature specimens and in the fresh shells cleaned with potash.” The same is true
of the cuticular canals of the glands of the lobster, except that the tubule is always
apparently straight and is never effaced.

Lang (114) mentions some of the many cases in which glands have been described
in the body and appendages of various crustacea, attributing to some of these ‘“der-
mal” structures an excretory function, a fact which, he says, may be proved by feeding
with carmine.

Unicellular glands of a remarkable character have been described in the append.
ages of various amphipods by Nebenski (140), Claus, and others. Here they are found
in both sexes, but are confined in Orchestia to terrestrial species. Nebenski thinks that
in the latter they may serve a respiratory function by keeping the gills moist.

The glands situated in the mouth parts, when stained in Ehrlich-Biondi anilin
mixture, select the green with more regularity, the nuclei taking up the red. This,
however, may be due to slightly different methods of treatment in washing out the stain.

The differences between what appear to be the resting and active gland, illustrated
in figs. 212, 211, which are fairly characteristic of the swimmerets, immediately before
and after ovulation, respectively, should not be given undue importance, since these
conditions are met with, though less commonly, in other parts of the body.

Micro-chemical reactions point clearly to the glandular nature of the large periph-
eral cells of which these organs in certain places are composed. It is probable that
in the pleopods they are concerned with the secretion of cement, for the reasons
already given. What, then, is the function of the eccentric bipolar cell? Is it a reflex
center for the gland, or is this a sensory cell which conveys impulses received from
without to a reflex center in the central nervous system governing the secretory
activity of the glandular cells? If the former supposition were correct, another ques-
tion would remain to be answered: What are the organs of the sense of taste? The
remarkably quick responses which are obtained upon stimulating the mouth parts
immediately suggest the presence of gustatory organs. Such animals as the lobster
and crab undoubtedly possess the sense of taste, but no organs have yet been
described to which this function could be ascribed. Huxley says:

It is probable that the crayfish possesses something analogous to taste, and a very likely seat for
the organ of this function isin the upper lip and the metastoma; but if the organ exists it possesses no
structural peculiarities by which it can be identified.

The labrum of the crayfish, so far as I could ascertain from a single specimen
which I sectioned, contains no such glandular organs as occur in the lobster.

If it is inadmissible to regard any of the tegumental “glands” as gustatory
organs, we must conclude that no distinct organs of taste can be detected in this
animal, which has the power of discriminating its food. Is it possible, as Lemoine
suggested (118), that the sense of taste is in some species blended with that of smell

132 BULLETIN OF THE UNITED STATES FISH COMMISSION.

and touch? Lemoine, who experimented with the crayfish, found that even the thickest
parts of the carapace were sensitive, and that the parts which abounded in hairs were
the most sensitive. Touching the hairs determined the movement of the claws and
thoracic legs.

Milne Edwards considered the buccal cavity as the seat of the sense of taste, but
although the experiments made by Audouin and himself convinced him that the sense
was developed, he failed to find any special organs. (58, I, pp. 112-113.)

Lemoine experimented upon the buccal cavity, and especially the labrum, using
a great variety of stimulants, such as salt, pepper, tobacco, ammonia, and electricity.
He describes the labrum of the lobster, but, strange to say, did not discover the organs,
with which it is packed full. He found that the inner face of this body was extremely
sensitive. A nerve enters the labrum on each side. This gives off lateral twigs near
the point of entry and numerous terminal branches toward the median plane. He
supposed that these terminal filaments supplied the short hairs which were erroneously
supposed to cover the surface.

The sete of crustacea have tactile, auditory, and probably olfactory functions.
The sensory seta is hollow and stands over a canal, which penetrates the integument,
and a nerve fiber passes up into the lower part of the canal. (84.)

The organs of taste in insects, according to Lubbock, are modified hairs, situated
either in the mouth or on the organs immediately surrounding it. Nine different
antennal organs have been described in the Hymenoptera. Some of these antennal
hairs serve as organs of touch and smell, and possibly for hearing also.

I have already called attention to the fact that while the pleopods are studded
with thousands of microscopic glands, these appendages in the male are almost devoid
of them. Their occurrence in the brachyura, where indeed they were first described
by Braun (23), might support the theory that they had, in such cases, a function to
perform independent of the production of cement, since it has been shown that the
crabs possess a special cement-forming organ in the epithelial lining of the glandular
receptaculum seminis. We must therefore conclude that in the brachyura the work
of the glandular receptaculum seminis is supplemented by that of the pleopodal
glands, or that the latter possess another function.

On the other hand, Leydig (122) has maintained that there is a close relation
between gland cells and sensory cells, the two kinds of cells resembling each other in
general structure and in the disposition of the cell contents. He found in the sensory
cells of the skin of some vertebrates what seemed to correspond to cuticular secre-
tions in gland cells.!

The gland of the type which we have been considering is undoubtedly a very
primitive organ in Arthropods. It has probably been modified to perform different
functions, with a minimal change of gross anatomical structure. What the function in
every case is we can not for the present say with any degree of certainty. While the
question is a puzzling one, it seems to me safer to regard all such structures, wherever
they occur, in esophagus, the intestine, the labrum, pleopods, or outer integument of
the body, whether in Decapods, Limulus, or in other forms, where they will doubtless
be discovered, primarily as glands. We may add that in the labrum, and perhaps in
other parts of the external integument of the lobster, and in Limulus, they may have

' Jickeli, according to Leydig, believes that in certain Hydropolyps which he studied sensory
cells are converted into gland cells. (£22.)

THE AMERICAN LOBSTER. 33

a secondary sensory function. I have not examined the glands which occur in the
alimentary tract, and can not say whether they possess a precisely similar structure,

Upon the supposition that the tegumentary organs are never sensory in function,
we would have to conclude that the reactions which were obtained upon stimulating
the dead shell had their seat in sensory elements in the vicinity of hair pores, and that
the sensory hairs themselves are open at the tip, or at least have thin walls. I have
usually found sensitive areas covered with setze,'! and while these do not normally
open at the tip, the cuticle is so thin at this point that chemical stimuli might be readily
conducted through them.

There is, however, one organ which is very sensitive to chemical stimuli, and
which is entirely devoid of true setie in the adult animal. This is the labrum or upper
lip. Its structure certainly favors the view that the peculiar tegumental organs which
it contains in such abundance may be the seat of the sense of taste.

There can be no doubt that the labrum is very sensitive to various stimuli, as
Lemoine clearly showed many yearsago. In the specimens which I examined with
particular care no sete of the ordinary kind were present on either the upper or lower
sides, and the only direct channel for the passage of chemical stimuli from the surface
of the dead cuticle to sensitive structures below it were the ducts of the tegumental
glands. After the labrum had been cleaned by boiling it in a strong solution of potas-
sium hydrate, the cuticular structures were clearly demonstrated. The only sete
present lie in four small rounded clusters of 12 to 15 each, near the base of the labrum
and on its upper surface, where the cuticle has been reenforced by deposits of line.
These sete are microscopic, measuring only one-tenth millimeter in length. Moreover,
each is traversed by a duct which apparently opens at the surface and without doubt
belongs to a tegumental gland. The upper surface of the labrum is abundantly
sprinkled in other places, especially about the tip, with the minute pores of glands.
These are sometimes in clusters, and their aggregate number is very great. When we
examine the inner surface of the labrum we see it covered with sieve-like patches, each
sieve containing sometimes as many as 60 or 70 holes, the openings of tegumental
glands. At the anterior end these merge together so that the openings are exceed-
ingly numerous. (Compare figure by Lemoine, 778.)

Lemoine evidently mistook the ducts in the sieve-like areas for hairs, and has
figured them incorrectly. The ducts project from the inner surface of the cuticle,
(compare fig. 170) and in no instance were true sete or hairs present on any part of the
adult labrum.

Experimental evidence seems thus to point to the possession of a subsidiary gus-
tatory function on the part of tegumental organs of the labrum, and possibly of other
appendages about the mouth. This would imply that the stimulating particles are
conveyed to the lumen of the organ, and thence to the central rosette. It would
of course be absurd to suppose that the apparently similar organs in many other
parts of the body, as in the carapace, possessed a similar function. While such a
conclusion is not perfectly satisfactory, it is at least worthy of consideration.

'The walls of the seminal receptacle contain very few glands, but are copiously supplied with
clusters of setie. As I have already shown, they are very sensitive to chemical stimuli.

Chapter VIII—VARIATIONS IN COLOR.

In the study of the color of animals we must distinguish between (a) variations in
colors themselves and (b) variations in color patterns. The variation in colors, which
Bateson calls “substantive variation,” may be the result of a physical or chemical
change and has no vital significance, like the change of yellow phosphorus to the red
variety, of blue to red litmus, or of green to red pigments in autumn leaves and in the
shell of the living lobster when the latter is boiled. “ Different colors,” says Bateson,!
“are liable to different discontinuous variations; as instances may be mentioned black
and tan in dogs, olive brown or green and yellow in birds, red and blue in the eggs of
many Copepoda,” ete. ‘Discontinuous color variation of this kind is one of the com-
monest phenomenain nature.” The dark green and golden yellow in the eggs of several
species of Alpheus and many other macrura is a characteristic example (94). Such
changes can have no protective or adaptive significance.

The color of the lobster? is primarily due to the presence of pigments, either in
solution in the blood or in the form of granules in the protoplasm of certain cells,
particularly the chromatoblasts, which lie beneath the cuticular epithelium. The
chromatoblasts are richly supplied with blood, which flows in a system of irregular
sinuses through the spongy tissues underlying the epidermis.

In the adult lobster the shell is an opaque, dead substance, and the pigments
which give it color are excreted by the chromatoblasts lying in the soft skin which is
exposed upon removing the shell. This skin is flecked and mottled with scarlet, and
it takes only a simple magnifying glass to see that its color is due to the branching
pigment cells, accumulations of which correspond to the blotches of pigment on the
shell. The excreted pigments undergo physical and probably chemical changes in the
shell, and become of a very different color from that of the chromatoblasts. :

Since the colors of the adult lobster reside in a dead body—the pigment layer of
the shell (see pp. 77-78)—it is evident that no changes of a vital nature can take place
after this is definitively formed. A young male, 10 inches long, drawn and colored from
life, is represented on plate 16, fig. 22. This may be taken to represent the average
color in lobsters with moderately hard shells.

NORMAL COLORATION.

There is no apparent sexual variation in the color of the lobster. The following
detailed description is drawn from a female 103 inches long, with elastic or “ buckle”
shell and with nearly ripe ovaries.

The general cast of color of the upper parts is dark bluish-green, mottled and
speckled with very dark greenish-black spots; tail-fan light greenish-olive; sides of
carapace brownish-olive, conspicuously spotted with small greenish-black spots; sides
of abdomen marked in the same way, spots not aS numerous; no spots on upper
surface of uropods; large chelze above dark bluish-green, almost black, with suffusions
of orange on propodus; tubercles and spines bright red; spines of rostrum, antenne,

' Materials for the study of variation, treated with especial regard to discontinuity in the origin
of species, by William Bateson. 1894.
2 The color variations in the young are discussed on p. 184.

134

THE AMERICAN LOBSTER. 135

pleura of third to sixth abdominal segments, and of appendages generally, vermilion ;
worn points of spines or worn surfaces of tubercles whitish; orange area of crushing
chela (on propodus) mottled with dark green; walking legs bluish-green; bright sky-
blue on basal joints, and tufts of set reddish.

Tendon marks: (1) A large poreelain-like whitish spot at junction of the cervical
and branchio-cardiae grooves. Passing down the cervical groove are (2) numerous
white or greenish white spots; (3) a large irregular yellowish-white spot occurs in a
depression which lies about an inch behind the first antenna, and one-half inch from the
dorsal surface, measured vertically; (4) a small white spot is seen about five-eighths
inch behind the second antenna and five-sixteenths inch above the cervical groove.
These spots are very characteristic, and are more prominent in the young than in the
adults. They first become conspicuous in the fifth stage. (Compare plates 24, 25.)

The edge of the carapace is scalloped opposite the appendages, probably an
adaptation for the movement of the legs;' largest scallops opposite the large chelipeds ;
a wide seam-like border, disappearing behind, forms part of the lateral area of absorp-
tion (see p. 88); color of absorption area light blue; yellowish spots on either side of
second to sixth terga of pleon, most marked on second, third, and fourth segments.

Lower surface of large chele reddish orange; bright red at the tips; bluish-green
at edges, and on hinder parts of the propodus, and on the other joints; basal joints ot
smaller legs sky-blue varied with brownish-olive; wing-like pieces of seminal receptacle
bright blue; swimmerets flesh color, edged with reddish; intersegmental membranes
of abdomen nearly colorless; lower side of tail-fan brownish-olive; telson and uropods
edged reddish-brown; fringes of silky hairs of the same color.

There is generally an under tint of olive on the body verging into a greenish-blue
on the one hand or light reddish-brown on the other, the whole upper and lateral
surfaces being spotted or mottled with dark greenish-blue or blue-black, the spots
often confluent on the upper surface.

VARIATIONS IN COLOR.

The coloration is uniform in plan, but exceedingly variable in details, much more
so than we see in the case of the intricate color patterns of many insects. The bril-
liancy and purity of the shell pigments depend largely upon the age of the shell or its
condition with respect to the molting period. The pigments are usually most brilliant
immediately after the molt, when the cuticle is thin and translucent, and dullest just
before ecdysis begins, when the old shell encumbers the body.

The pigment cells themselves, which, as we have seen, reside in the skin or immedi-
ately below it, are subject to vital changes, but when the shell is once hardened the
color of the animal is fixed. It is certain, however, that under the action of light,
or from other 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. I
recently witnessed a very interesting demonstration of this fact. The fishermen at
Menemsha, at the western end of Vineyard Sound, saved all the egg-bearing lobsters
which they caught in June, 1894, for the hatchery of the Fish Commission, placing them
in a floating skiff, covered only with netting and thus exposed to the full glare of the
sun. Toward the last of the hatching season, when operations in the hatchery had

'The development of the carapace shows that these notches have nothing to do with the primi-
tive segmentation of the body.

136 BULLETIN OF THE UNITED STATES FISH COMMISSION.

ceased, I made no visits to Menemsha from June 22 until July 16, when I found about
a dozen lobsters in the car, where they had been imprisoned from two to three weeks.
They were without exception of a brilliant blue color, and were very conspicuous
when placed with other lobsters recently taken in the Sound. They were all old-shell
females, most of which had hatched their eggs and were approaching their molting
time. All the green pigment of the shell had become light cobalt-blue, which, inter-
spersed with the usual Naples yellow tints, gave them a very striking appearance.

According to the observations of MacMunn (132), the coloring of the skin of the
lobster (Astacus gammarus) and crayfish (Potamobius fluviatilis) is due to the presence
of chromogens, which are converted on very slight provocation, as by dehydration,
oxidation, or some molecular change, into a red lipochrome, resembling rhodophan.
Everyone is familiar with the wonderful change of color which the adult lobster under-
goes when boiled,’ and according to MacMunn the beautiful blue pigment of the larva]
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 well seen in recently molted lobsters,
where the colors are very brilliant. When placed in alcohol, the soft-shelled lobster is
first reddened, and then in a short time completely bleached, while a lobster with a
hard shell treated in the same way will retain some of its color for a long time, if not
indefinitely. The same changes are seen when the dark-green eggs are treated with
alcohol or boiling water.

The lipochromes are pigments of a very wide distribution in the living world,
occurring in green leaves, in yellow flowers and fruits, and it is said that the ver-
tebrate retina, ‘‘egg-yolks of different species of animals, the yellow, green, or red
pigmented integuments of various invertebrates and vertebrates from fishes to birds,
owe their coloration, with few exceptions, to dissolved, granular, or diffusely distributed
lipochromes.” (132, p. 95.)

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), and
in the exoskeleton of crustacea. 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.” (132, p.62.) 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.

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; (4) we
should also add 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, Maine, 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 (133) speaks of meeting with cases of melanism
in crabs, where in consequence of a lesion of the skin the crab becomes entirely black—
‘‘charbonné,” as the sailors describe it.

1In France the lobster, Astacus gammarus, is said to be called the ‘‘red cardinal of the sea,” and
the Norwegian lobster, Nethrops norvegicus, I am informed by Dr. Lénnberg, is called by the fishermen
in Sweden Kejsar hummer, or emperor lobster, on account of its color and spines.

THE AMERICAN LOBSTER. 1a

Changes in color pattern are more elusive. There is (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.

We will presently consider in more detail the variations which have just been
enumerated, but must first speak of the eggs.

COLOR OF THE EGGS.

The eggs of the lobster furnish a good example of substantive variation. The
body of the animal is opaque, so that it is affected but little by the color of the ovaries,
and not at all when seen from above, by that of the external eggs.

The freshly laid ovum is of a dark green (fig. 24, pl. 17), sometimes almost black,
color, due to the presence of a dissolved lipochromogen. The golden-yellow variation,
which is often associated with dark green, as in the eggs of Alpheus heterochelis and
A. sauleyt (94, p. 375), has never been observed, but occasionally the ova are of a light,
almost pea-green color, or some tint between this and very dark green. Rarely the
new eges are light grayish green. I received a lobster from Woods Hole in December,
with external eggs of a very light greenish straw-color. (See fig. 25, pl. 17.) These
were in an early stage of development, and had been laid but a few weeks. It was
the most striking color variation in the ova which I have yet seen. Such changes as
these can not be interpreted as having any adaptational significance.

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 com-
pound of starch and iodine upon the successive application of heat and cold, and to the
variation in color which sometimes appears in the living animal at the time of the molt.
Soon after the water has been brought to the boiling point the red color becomes
permanent.

BLUE LOBSTERS.

Lobsters of a deep, almost uniform ultramarine color are sometimes met with and
never fail to attract attention.' The color, which is often of a rich indigo along the
_ middle of the upper part of the body, shades off into a brighter and clearer tint on
the sides and extremities. The upper surface of the large claws is blue and purple,
faintly mottled with darker shades, while underneath is a delicate cream tint. The
under parts of the body tend also to melt into alight cream color, and this is also true
of the spines and tubercles of the shell and appendages, which are usually bright red.

A lobster of the foregoing description was caught off Hurricane Island by Thomas
Garrett, in April, 1874. It was a female, had a hard shell, and weighed about 2 pounds.
A very bright blue lobster was taken at Grand Manan, Maine, in August, 1893.

'DeKay (5Z) speaks of a variety of lobsters called Bluebacks, but his impressions that they are
derived from one part of the coast, that they have thin shells, and that they are chiefly seeu in early
May, were all erroneous. He also remarked that they were highly prized by epicures.

138 BULLETIN OF THE UNITED STATES FISH COMMISSION.

I have never seen a blue lobster of perfectly uniform tint or without markings
on the shell; yet lobsters which very nearly answer this description are occasionally
taken, according to abundant testimony. Passing from this condition, there is a graded
series of colors, from the decidedly blue to the distinetly blackish or bluish green.

There is a well-preserved skeleton of a blue lobster in the museum of the
Peabody Academy of Science at Salem, Massachusetts.! This specimen is a male,
11% inches long, and has a hard shell. The carapace is deep indigo above, but lighter
on the sides with rather faint spots of light blue. The “tail” is of a purplish cast,
with fine spots or marbling of dark blue. The large claws are purplish above, with
abundant darker blotches, while they are cream-colored below, with some fine blue
spots. The other legs are cream-colored, washed or speckled with blue.

Mr. J. W. Savage received at Boston, in June, 1893, about a hundred exceptionally
blue lobsters from Nova Scotia. They had “hard shells,” and would average 13 pounds
each in weight. As he expressed it, ‘they were as blue as bluejays.” In April of
the same year Mr. A. P. Greenleaf, of Boothbay, Maine, received also from Nova
Scotia, as he informed me, two thousand or more very blue lobsters. He says that
the usual spots and other markings of the shell were not conspicuous, and that the
colors were so bright that he was almost afraid to ship them to market. A female
egg-bearing lobster from Nova Scotia, which 1 examined in September, was of a dull
leaden: blue color over the whole upper part of the body. The lateral edges of the
carapace were sky-blue, the claws very dark, almost black, above, and dull red below.
I have already referred to the bluing of lobsters (p. 135), which is due to either a
physical or chemical change in the shell pigments and has no adaptational significance.

Blue crayfishes described by Lereboullet (719) were “of an azure or cobalt color
more or less intense; the claws deeply colored; the legs paler, and the lower parts of
the body of a pale red.” He thought that the shell contained three kinds of pigment—
red, blue, and green, and that in the red and blue varieties one of these pigments was
excessively developed.

RED LOBSTERS.

Occasionally red living lobsters are seen, which are very rarely as bright in
color as those which ‘have been boiled. Mr. F. W. Collins, of Rockland, Maine, had
a lobster of this variety in September, 1890. It was taken in Dyers Bay, near Jones-
port, Maine. It had a hard shell, and when in the floating car with other lobsters
was very conspicuous for its bright color.

Mr. S.M. Johnson informs me that lobsters of this interesting color variety are
met with ‘more or less frequently.” Speaking of one which was obtained in 1892, he
says that “although taken by itself the color was somewhat paler than the ordinary
boiled lobster, yet if put with others that had been boiled it would have been hard to
distinguish the difference.”

Through the kindness of Messrs. Johnson and Young I received on April 9, 1894,
aremarkably perfect specimen of a red lobster, of which I have made a drawing
colored as accurately as possible from life (plate 16, fig. 21). It was alive and active
when it reached Cleveland, had a fairly hard shell, was without external eggs, and
measured 113 inches. Except in color, it was perfectly normal. It was caught in the
vicinity of Mount Desert, Maine. The ovaries, which were immature, were of a light-

‘Thad the privilege of examining this and other specimens in the museum through the courtesy
of Mr. John Robinson, treasurer of the Peabody Academy of Science.

THE AMERICAN LOBSTER. 139

green color. Messrs. Johnson and Young consider this variety very rare, since they
have seen but one other in which the red color was so bright and uniform in life.

The color of this animal, as shown on plate 16, was very brilliant. There was not
the slightest trace of any blue or green pigment about any part of it, except at some
of the articulations, nor of any other color except a light-reddish russet or orange.
The eyes, however, possessed the usual black pigment, and on this account were
exceptionally prominent. The flagella of the antenne, the tips of the walking legs, and
posterior margins of the tail-fan were brilliant red. The color on the upper surface of
the large claws was rather brighter red than on the lower. <A good idea of the natural
color of this lobster may be had by imagining the color of the whole animal to be of
the orange-red tint which is normally seen on the under side of the large claws.

The spines were not brighter red than the other parts, but were worn white at
the tips, as is usually the case. The sete over the various parts were of the usual
reddish-brown color. The color of the carapace may be described as light orange-red,
covered with a reticulate or very delicately lined pattern of darker red, and mottled
with white. The light spot which is seen midway between the roots of the second
pair of antennze and the cervical groove was very large, as were also the whitish
tendon-marks of the cervical groove itself.

The sternal calcified portions of the animal were snow-white, washed faintly with
orange-red. The seminal receptacle, which is usually bright blue, was pure white; the
Swimmerets very translucent and faintly tinged with red; under side of tail-fan a
uniform pale reddish orange.

This seems to be a remarkable case of a discontinuous color variation, which is
the result of a chemical change similar, in all probability, to that which occurs after
death, as when the animal is boiled.

Lereboullet (119) says that a red variety of the crayfish was found in certain
Streams in the Rhine valley. It was usually small, though sometimes of the average
size. ‘They are all of a uniform brick-red color, without spots, and resemble cooked
crayfishes perfectly; the legs and lower parts of the body are always very pale.”

CREAM-COLORED LOBSTERS.

A light cream-colored lobster, without any darker spots visible upon it, was cap-
tured at North Waldoboro, Maine, about 1882. It was between 10 and 11 inches long.
I saw this specimen, but not until it had been preserved in alcohol.

Mr. J. W. Fisher, of Eastport, Maine, informed me that in the winter of 1893 a
lobster was caught at Deer Island, Maine, which was 11 inches long and of a light
cream-color. It appeared very white in the water. There were no visible spots or
markings upon it. A lobster of similar appearance was taken in Boston Harbor by
Mr. J. W. Savage, in August, 1892. The under side of the claws was light red, which
was not intensified upon boiling.

Perfect albino lobsters, without trace of natural pigment in the eyes, or parts of
the exoskeleton, have never been captured. ‘ Albinism,” or the various stages of an
approach toward this condition met with among crustacea, are, according to Malard
(133), in all probability but particular cases of adaptive coloration. It seems to me
far more likely that such cases are primarily non-adaptive. In the lobster there has
been a degeneration, and in some cases a final loss of pigment. This may be the last
of a series of changes which we see begun in the live red lobster. The latter is no
more or less protectively colored than the former.

140 BULLETIN OF THE UNITED STATES FISH COMMISSION.

A specimen of a gray lobster (Astacus gammarus) was described at a meeting of
the Société Philomathique of Paris, on December 12, 1891, by M. Martin. It was
captured at St. Vaast-la-Hougue, in a trap with several perfectly normal lobsters.
The dorsal part of the carapace of the abnormal specimen was of a dark yellowish-
green color, with greenish-black spots. The green color disappeared rapidly on either
side of the dorsal median line, the yellow remaining, and passing into almost pure white
on the sides. There was not the least trace of marbling and none of the pronounced
blue color of the average lobster. The pleon was yellowish-green above, and yellow
on the sides. Large irregular spots of a deep bluish-black color ornamented each
segment, even in the dorsal parts, but without forming the usual marbled pattern.

Martin rejects the hypothesis that this deficiency of color may be due to the
absence of light, supposing the lobster to have lived in a dark crevice in very deep
water, and regards this variation as adaptive, a conclusion which seems to me
gratuitous. He says, in a note, that M. Biétrix, of Concarneau, had a white lobster,
kept in a pond, which recovered its blue color at the next molt. A young male of
Alpheus saulcyi, which I once kept for several days in an aquarium, molted and lost
completely the bright vermilion color of its claws. (94, p. 381.)

Casual or temporary decoloration occurs in many species of crustacea, as in Can-
cer pagarus, of which Malard (153) says that he has met with many cases of young
individuals living under stones in old oyster parks in the island of Tatihou, while the
permanent absence of pigment is characteristic of certain well-known burrowing
erustacea which live in the sand, such as Hippa, Callianassa, and Gebia. It is doubtful
if the entire absence of pigment in such a form as Callianassa can be regarded as
adaptive; first, because the animal burrows, and is for the most part concealed; and
secondly, because its whiteness makes it a more conspicuous object on the sand than
it might otherwise be. This condition may, however, be the last term in a series of
changes, some of which were distinctly adaptive.

VARIATIONS IN COLOR PATTERNS.
SPOTTED LOBSTERS.

The spotted lobsters—“‘ calico,” or ‘“‘leopard lobsters,” as they are variously called
by fishermen—exhibit an interesting and striking coloration, which is somewhat rare.
They appear to be occasionally captured, however, all along the coast. An experienced
fisherman at Rockland, Maine, said that he usually took one or two of this variety in
the course of the season.

There is a well-preserved spotted lobster in the museum of the Peabody Academy
of Science, a female with hard shell, 114 inches long. The whole upper part of the
body is of a light-yellow color, with purplish-blue pigments (in the dried shell) so
arranged as to give a spotted or marbled appearance. The light-yellow spots on the
carapace vary much in size and shape, the largest being half an inch in diameter and
of a slightly irregular, rounded contour. The spots are confluent at the hinder end of
the carapace, where they form a marked yellowish area. On the sides of the carapace
the spots are small and tend to flow together. The “tail” is marbled above with
irregular yellow spots, in excess of the darker color. The tail-fan is yellow, beauti-
fully mottled with reddish-purple. The appendages are spotted in the same way, light
yellow predominating. The large claws are dark purplish-red above, with obscure
spots; but on the under side, they are of the usual bright reddish-orange color,
spattered with purple.

THE AMERICAN LOBSTER, 141

PARTI-COLORED VARIETIES.

Once in a while a lobster is caught which exhibits a remarkably abnormal colora-
tion. A lobster which would weigh about 2 pounds was captured near Long Island,
Portland Harbor, about the year 1886. One half of the body was light yellow, clearly
defined up to the middle line of the back from the color of the other half, which was
bright red. There were no spots on the shell. This specimen was exhibited in Boston,
and afterwards sent to Professor Baird.

De Kay mentions a similar case (51). He says:

In June, 1840, I saw in the Fulton Market a lobster which was of two colors, distinctly separated
by a medial line from the tip of the rostrum to the middle extremity of the plate of the tail. One side
of the body and all the members were of a light sky-blue, and the other of the usual olivaceous green.

Mr. 8. M. Johnson informs me that it is not uncommon to get a lobster in which a
part of the body is pale red while the rest is normal in color, and that a few years ago
he had a specimen in which this difference in color was marked by the line running
through the middle of the back, and that even one-half of each ‘“feeler” was light
and the other dark.

Buckland (28) mentions the case of a half “albino” lobster, which he received in
May, 1868. He says:

One side of the barrel was blue and the other was white. The blue turned red on boiling, but
the white did not. There appeared to be no pigment in the white part of the shell.

Boeck (20, p. 225) says that in 1868 he found a lobster near Haugesund, one half
of which was of a greenish-black and the other of a light-orange color, there being a
Sharp and clearly defined line, which ran lengthwise and divided the shell into two
parts of equal area. This closely resembles the odd variations which we have just
noticed in the American species.

Lovett (128) has described a number of color variations in lobsters from the
island of Jersey. One which is particularly mentioned—a female with eggs—was of
a pale lavender color, with a mauve spot on the carapace and with bright blue claws.
The usual mottled markings on the sides of the thorax were rather indistinct. He
speaks also of having observed a full-grown female with eggs of a pale-reddish color,
with bright antenne.

Carrington and Lovett have described the great chromatic adaptability of the
common green crab, Carcinus meenas (35).

Boeck says that the European lobster, taken near the mouths of fiords in Norway,
is lighter in color than is usual, while farther out to sea it becomes much darker,

Malard thinks that these peculiar color variations are due to the loss of certain
pigments, in consequence of insufficient light, in the deep grottos or rocky crevices
where the lobsters may have lived.

Protective coloration and chromatic adaptability to the immediate environment
are common to a large number of the crustacea. It seems to be least observed in
the highest representatives, the Brachyura. According to Malard this chromatic
adaptation is effected either (1) chemically, by the modification of pigment under the
direct action of light, or (2) physiologically, by the action of pigment cells stimulated
by light, indirectly through the eyes and central nervous system.

Pouchet has made some interesting observations (see 733) on the variations of color
in thecommon shrimp, Palemon. It was found to be most variable when 3 to 4 cm, in

142 BULLETIN OF THE UNITED STATES FISH COMMISSION.

length. When captured by the fishermen they are usually of a rose or delicate lilae
color, but lose these tints or become of a light-yellowish hue when kept in vases with
white bottoms. In black vases they turn to a deep brown. These effects are produced
by the reaction of two kinds of pigments, the cyanic pigments which are generally in
a state of solution, and the pigments of the xanthic series (red, orange, and yellow),
by the action of the chromatoblasts. Malard states that Jourdain has shown that if
the eyes are removed and the animal is kept in darkness, a red color is always obtained.

Certainly, one of the most striking cases of protective coloring met with in the
crustacea is that of the inhabitants of the floating islands of sargassum which are
encountered in the Gulf Stream or along its borders. This algais of adirty yellowish-
brown color, often flecked with white, when its floats are incrusted with the bleached
skeletons of bryozoa. This appearance is emphasized by the numbers of goose bar-
nacles which are attached to the fronds. A small crab which is an important colonist
of these islands is brown, with a large snow-white spot on its back; and the shrimp,
of which there are several species, are colored in a similar manner, the body being
dappled with brown and white.

We must place in another category the gaily dressed shore crab of the West Indies,
Gegarcinus ruricola, whose brilliant hues and bizarre coloration are clearly without
protective significance. This beautiful crab burrows in the mangrove swamps at about
the level of high water, and is very common throughout the Bahama Islands. After
a drenching rain the green boughs of the mangrove suddenly blossom out with crabs.
Some of them have crimson legs, a dark purple body, with a large yellow spot on each
side of the carapace, while in others these colors are reversed. Others again are
nearly black, or the carapace is orange or straw color, flecked or marbled with purple,
in an endless series of patterns, so that no two are alike. It is possible that this is
an example of warning coloration, such as is seen in many gaudy insects, serving to
protect them from the assaults of birds and other enemies, or it may be a case of
substantive variation, without any vital significance.

The colors of deep-sea animals which live in total obscurity can not be of any
utility to the animal as a source of protection. The colors may be very brilliant—red,
scarlet, orange, rose color, purple, violet, and blue being 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. 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 its whole
upper surface, tend undoubtedly 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, particularly on the
upper surface. The under side 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.

Chapter IX.—VARIATIONS IN STRUCTURE.

Deformities in the adult stages of the higher crustacea center chiefly in the large
claws, which are more subject to mutilation than any other parts, owing to their
constant use as weapons. We will therefore consider first the variations in these
appendages.

NORMAL VARIATIONS IN THE LARGE CLAWS.

Aristotle (4) says of the claws of the lobster: ‘“‘In the Astaci alone it is a matter
of chance which claw is the larger, and this is in either sex.” The difference between
the right and left claws is greatest in the small fiddler-crabs where, as in Gelasimus,
the large claw, according to Bate, can not reach the mouth, a power which it must
have originally possessed.

It seems, as Aristotle remarked, a matter of chance whether the crushing-claw is
on the right or left side of the body; but this is not really the case. I have shown
that in Alpheus sauleyi, where the large crushing-chela 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 crushing-claw 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. (For a statement of the facts, so far as they are known, see 94, p. 376.)

The large claw occurs about as frequently upon the right side of the body as upon
the left, without distinction of sex, as shown by the following table, embracing 2,433
individuals:

Crushing | Crushing | :
Sex. clawon | clawon | Bot h els
right side. | left side. Seca
Mal essepeprseemstsieeieiciacts oarelere 562 628 iL
Memalesitees see seceiencemt ce 602 638 2
Motalye tee eons See 1, 164 | 1, 266 3

ABNORMAL VARIATIONS IN THE CLAWS.
SIMILAR CLAWS DEVELOPED ON BOTH SIDES OF THE BODY.

A variation sometimes occurs in which the normal differentiation of the great
claws is wanting. Both claws are similar, developed either for cutting or crushing.'
In examining over 2,400 lobsters, only 3 were found in which this abnormal variation
was present. It is, therefore, undoubtedly rare, and apparently has never been
previously described. Before examining these cases in detail it will be best to notice
the normal characteristics of the claws. This description is taken from a female—
length, 11 inches; weight, 24 ounces—with hard shell (compare fig. 20a, plate 15):

Crushing-claw: On right side; seven marginal spines on propodus, third spine
(from peripheral end) depressed; a small spine opposite the latter on upper side of
propodus. There is a small tubercle on the upper side of propodus, near articulation of
dactyl; in a corresponding situation below there are two tubercles, one considerably

'T have heard of a single case reported by a fisherman, where similar crushing-claws were
developed on both sides of the body.
143

144 BULLETIN OF THE UNITED STATES FISH COMMISSION.

smalier than the other; a small tubercle on upper side of propodus, on outer margin,
near carpus. There is considerable variation in the number and prominence of these
processes, particularly the marginal ones.

Outting-claw: Six marginal spines on propodus, second and fifth depressed ; other
processes present, as in corresponding claw.

ABNORMAL VARIATION.—(1) Female; length, 105 inches; hard shell; cutting-
claws on both sides similar; Woods Hole, Massachusetts, March, 1894.

Right cutting-claw: Small tubercles of propodus, near aactyl, wanting.

Left cutting-claw: Transverse scar-like groove on propodus, at level of articulation
of dactyl; one small tubercle on upper surface of propodus, near dactyl; two very minute
ones below; five marginal spines, third bent inward, rest turned forward and upward.

(2) Female; length, 103 inches; hard shell.

Right cutting-claw: Five marginal inner spines on propodus, third depressed; no
small tubercles near joint of dactyl present.

Left cutting-claw: A little smaller than right; 5 marginal spines, none depressed ;
one small tubercle on lower side of propodus near dacty].

(3) Male; length, 10 inches; hard shell; both claws relatively small, having been
regenerated; length of propodus, 32 inches. (Plate 14, fig. 19, from photograph.)

Right cutting-claw: Seven marginal spines, second and fourth depressed; one
small tubercle on under side of propodus, near dactyl.

Left cutting-claw: Five marginal spines, second depressed; one very small tubercle
on upper side of propodus near dactyl; two very minute ones below.

There seems to be about as much variation as regards the details here mentioned
in normal symmetrical claws as in the abnormal symmetrical ones, and it is probable
that in either case the conditions met with are to some extent congenital.

DIVISION AND REPETITION OF APPENDAGES.

The curious monstrosities which occur in the appendages, particularly in the large
claws of the lobster, have attracted the attention of naturalists for a long time. They
were noticed by Von Berniz (17) over two hundred years ago, and some good figures of
the deformed claws of the crayfish were published by Roésel in 1755 (168). A careful
review of crustacean deformities, concerning the lobster in particular, was given by
Faxon in 1881. His paper was accompanied by valuable figures and a bibliography
(66). The general subject of variation as it affects the appendages of arthropods has
been recently treated in a masterly manner by Bateson in his invaluable work on
variation.'! The variations which concern the crustacea, particularly the decapods, are
fully described and illustrated, with references to the abundant literature. Bateson
shows that in most of the cases of supposed duplication of limbs in both insects and
crustacea 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 super-
numerary appendages make their appearance in secondary symmetry. If the normal
appendage which bears the extra ones is a right leg, “the ne rer of the extra legs is
a left and the remoter a right.”

‘Materials for the study of variation treated with especial regard to discontinuity in the origin
of species, by William Bateson, 1894.

THE AMERICAN LOBSTER. 145

The monstrosities noticed in the chelipeds of the lobster are mainly the result of
a secondary outgrowth from one of the two terminal joints. Rarely the appendage is
duplicated or triplicated; a case of the crayfish is reported with three extra claws
(see Bateson, p. 537). 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 parts is rare. Defective or deformed claws, the result of injuries
(see figs. 194,198) 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 repeti-
tion or duplication of parts.’

If the tips of the claws are snipped off near the articulation of the dactyl, the
lost parts are restored (see p. 105) as we have seen at the next molt. This restora-
tion is often perfect, but not always so. The condition seen in fig. 198 might have
been caused by a pinch and arrest of growth while the claw was soft (before the last
molt), or by the unequal growth from a stump, the end of the propodus having been
cut off by an enemy just before the shell was cast. In the latter case the member
could be only partially restored, and unequal growth would account for the distortion.

The dactyl shown in fig. 194 has probably had a similar history. All such cases
are the results of regeneration after injury. This can not be said of such a specimen
as that represented by fig. 189, where the dactyl bears upon its inner margin near the
tip a small conical prominence. This is smooth and is separated from the tip of the
dactyl by a shallow groove, as if there had been a normal bifurcation or division at
this point. What the primary cause of such a growth or swelling may be is not known,
but it is impossible to suppose it to be the result of injury.

With the appearance of such a simple outgrowth a progressive series of changes
seems to take place with every molt, such as is illustrated by figs. 189-193, plate 47.
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 (figs. 190,191) or somewhat
oblique plane (figs. 187,188). This fission apparently proceeds until one or both of the
supernumerary dactyls are entirely separated (figs. 192, 193). The opposing edges of
these become gradually toothed, so that each is almost an exact copy of the original
(see especially fig. 193, plate 47). According to the principles laid down by Bateson, the
part which is nearer the original joint corresponds with the appendages on the oppo-
site side—that which is farthest away with those on the same side of the body. This
is not strictly true in such a case as that shown in fig. 196, where the supernumerary
parts do not face each other, and in some cases the repeated part is single, not double.
In fig. 190 a short row of teeth marks the median plane of division and the opposing
surfaces of the incipient fingers are also toothed. In fig. 191 the outgrowth is divided
nearly to its base into two secondary DROSS, each of which resembles the joint of

'In 2,657 lobsters Caooed at Woods Hole, M: asst Vane) Feoyin Deeeanee to June, 1893-94, but
one case of repetition or formation of extra parts in the large claw occurred. No account was kept of
injuries, but in the months of December and January 7 per cent of all lobsters caught (54 in a total
of 725) had thrown off one or both claws. (See p. 103.)

A man who had been engaged in the business of canning lobsters for a score of years in Maine
told me that he had at one time nearly a bushel of deformed claws, which he had collected in the
course of his experience.

F, C, B. 1895—10

146 BULLETIN OF THE UNITED STATES FISH COMMISSION.

which it is a part. According to my interpretation, such a case as that shown in fig.
193 has gone through phases similar to those shown in figs. 189-191.

In figs. 192 and 197 the conditions are somewhat different, since the superadded
dactyl is single. I think there can be no doubt that a progressive division of the
propodus takes place in such cases. In fig. 192 the plane of fission in the propodus is
marked by spines very much as in fig. 190. There may be a line of median, unpaired
spines at the bottom of the groove, and bilaterally symmetrical spines upon its sides.
It seems probable that the conditions like those seen in fig. 197 could be derived from
such as are met in fig. 192 by the intervention of a single molt.

Faxon describes a very interesting case (66, plate 2, fig. 6) in which there appears
to be a duplication of the right cheliped down to the meros. The latter is partially
divided by a deep groove running across its distal end. It seems to me very
probable that we have here an illustration of the same process which is seen in
figs. 192, 197, only carried a step or two farther. In the former case the fourth joint
of the limb is undergoing a process of fission begun nearer the outer extremity, while
in the latter the sixth segment is involved. The supernumerary carpus in the case
figured by Faxon bears a stump-like segment, which looks like an abortive propodus,
corresponding probably to the abortive segment borne on the extremity of the super-
numerary branch of the propodus in fig. 197. In the latter case it is an undoubted
dactyl, and is smaller and more rudimentary than in fig. 192, where the fission of the
propodus has not gone so far. It is thus probable that with the extension of this
process, emphasized at each molt, the terminal segments may in some cases, aS in
those before us, atrophy and disappear, until we have, as in the example cited by
Faxon, only an abortive propodus left. Bateson regards this superadded member
as double, formed of two compounded parts. This may be so, but the same kind of
reasoning would lead us to regard such an incipient member as that seen in fig. 197
as double, consisting potentially of two dactyls and two propodi. The only apparent
reason for doing so lies in the supposition that such a superadded part arose as a
tubercle or budding growth on some part of the claw, probably in this case on the
dactyl, and was potentially a double member from the start, or at least capable of
doubling by a process of fission, as we see actually going on in fig. 190. Whatever
changes may have taken place precedent to the condition seen in fig. 197, there is no
evidence of fission in the extra dactyl unless the two spines (S, 8') be taken as such.

There seems to be a considerable gap between the condition seen in fig. 193, where
three dactyls are present, one of which is free, and that shown in fig. 192, where there
is asingle process. The latter is bent downward and toward the primary dactyl. Its
inner border has a spine (S) like that borne on the normal dactyl, showing this part
to belong to the left side. It bears also another spine near its articulation with the
propodus (S'), which might indicate that this toothless appendage was really a
double member. (See fig. 197, S, S'.)

Another good example of repetition of the propodus, with division of the bud, is
shown in figs. 187, 188, plate 46, which are from photographs. In this case the
bud has grown out obliquely from the under side of the propodus instead of from the
margin, as in fig. 190. The continuity of the outer margin is interrupted by a deep
groove which divides the bud into perfectly similar parts. In this case the teeth on the
inner margins of the supernumerary digits are not opposed. The outer or lowermost,
which is usually symmetrical with the normal part, makes here an angle of about 42°
with the normal digit, and the two supernumerary digits make an angle of 12° with

Bull. U, S. F,C. 1895. The American Lobster. (To face page 147.)

|

PLATE E.

SOG
s
LS

Cur 16.—Double right cutting-claw of female lobster, 11} inches long,
now in the American Museum of Natural History, New York City.
Seen from the anterior side. One-half natural size

S. C, supernumerary claw.

AN
Tn Si

oe. SS Bi

Ar
nia 4
Mai) ‘
ie

s

Cur 17.—Double right cutting-claw of the same lobster, seen from
above. One-half natural size.
S.C, supernumerary claw.

Drawn by I. H. Herrick.

THE AMERICAN LOBSTER. 147

each other. The pollux is depressed, so that when the claw is closed it falls almost
exactly midway between the normal and first superadded digit. The fission is marked
on the upper surface by a distinct groove. The total length of the propodus is about
24 inches (62 mm.),so that the lobster was not in all probability over 6 inches long.
The size of this claw as compared with the basal joints of the limb suggests that it
has been lately regenerated, and it is unfortunate that this interesting point can not
be determined with certainty.

In fig. 196 a similar monstrosity is seen in the dactyl of the cutting-claw. Here
the bifureating branch is near the apex. Each prong is furnished with teeth on the
inner side. A trimerous dactyl (fig. 195), one division of which is independent, in
the second or third pereiopod presents precisely the same relations which occur in the
first pereiopod (fig. 193), and probably they have been produced in the same way.

What is now most needed in clearing up questions in the interpretation of
deformities in crustacean appendages is to watch the molting of the animals and to
measure and record the change which occurs in the malformed individual at each stage
of growth. The abnormal developments seen in figs. 189-193 probably represent a series
of changes such as ordinarily occur in the same individual. What the course of events
really is between the conditions represented by figs. 195, 192 is not so clear.

While the true duplication, or even triplication, of limbs or parts of limbs is rare
in crustacea, it is occasionally met with; but it is an important fact, which Bateson
has emphasized, that “in arthropods and vertebrates such a phenomenon as_ the
representation of one of the appendages by two identical appendages standing in
succession is unknown. No right arm is ever succeeded on the same side of the body
by another arm properly formed as a right, and no crustacean has two right legs in
succession where one should be.”!

In the American Museum of Natural History, in New York, there is a specimen
of a lobster in which the right cutting-claw is perfectly duplicated from the carpus
or fifth joint. I was recently enabled to examine this interesting specimen and to
make some drawings of it, which are given in cuts 16, 17, plate EH.

The two cutting-claws resemble each other very closely in every detail and are
of almost exactly the same size, but each is relatively smaller than normal. The
measurements of each cutting-claw are as follows:

Right cutting-claws (abnormal) : Inches.
LORIN, OF THRO NON. oobeoatesbes ocaned osama bonso" suas souEEEcS asses osecad g
GHGS OREN Oe ORO NOMI, Cosa asecoasos sooecu conSlean ase, sas6 bon Seaboe 12

Left crushing-claw (normal) :

VERA. OF TORO NOC .¢ S505 sade sdhh55 SbeSeadesouadecs couGusasbecs coccuNdser 5
GreatesumDread TheOlm plo pOdUS term aeiscce se cisie selec a eeteeeicisereeria' 2

In the primary cutting-claw the dactyi closes normally on the propodus; in the
superadded claw (S. 0.) it is bent upward out of line with the cutting edge of the
latter. The symmetry of the two claws extends, with few exceptions, to the spines
upon their cutting edges and on the inner margins of the propodi. The carpus of
the limb is apparently single, but it has duplicated spines, and a deep groove at its
peripheral end shows that it is virtually double. The carpus and meros have been
twisted through an angle of 90°, so that their posterior surfaces face upward.

This specimen was obtained some years ago from a marketman in New York City.

‘Materials for the study of variation, p. 539,

148 BULLETIN OF THE UNITED STATES FISH COMMISSION.

Nothing is definitely known about the causes of repetition. It looks at first sight
as if the deformities in the appendages of the lobster and other arthropods could be
explained as phenomena of regeneration, though in this case there is addition rather
than replacement.

We have seen that where the cheliped is thrown off by reflex muscular contrae-
tion the bud of anew leg forthwith appears, and under favorable conditions grows into
a perfect limb. The tissues of this limb are developed out of the formed histological
elements of the stump. The process of regeneration is begun in this case as a direct
result of a loss or injury. The plane of fracture lies between the second and third
joints, and all parts peripheral to the second joint are reproduced. Repetition of parts,
however, occurs in many insects and vertebrates where no such regeneration of lost
appendages is known. However, the power of regeneration, which is present in all
organisms, differs rather in degree than in kind, and Weismann has shown that it has
probably been developed in many cases as a means of defense and protection to the
individual. (See p. 107.)

In the specimen of Palinurus (No. 808, Bateson, originally described by Léger
in 1886), where the left penultimate leg bears two supernumerary legs, both of which
spring from the basipodite, it certainly looks as if what would have taken place in
the case of loss of the original limb—namely, the growth of a new one from this joint
—had happened repeatedly, so that instead of the regeneration of one limb at a
time there is the superaddition of two; but where the limb is not cast off the first
superadded one is in secondary symmetry and belongs to the opposite side. If such
an interpretation will apply to this case, the various other repetitions and abnormal
growths which arise in more peripheral joints, as upon the sixth and seventh, fall into
the same general category. In the case of the growth of a new limb in consequence
of loss, however, all parts which are external to the plane of fracture are reproduced.
In the cases of repetition this 1s not usually the case, as Bateson has shown. The
bud which arises on the propodus (as in figs. 187, 190) may by fission give rise to a
second propodus, but not usually, if ever, to a dactyl.

It seems as impossible to suppose that such a deformity as that seen in fig. 187 or
fig. 189 is congenital as that it is the result of injury. The monstrosities which occur
in the embryo, which are considered in another place. are, however, in some cases at
least, the result of injury or unfavorable conditions.

Autotomy, or the casting of the claw at the second joint, is probably directly
accountable for the rarity of abnormal growths in the limbs of the higher crustacea.
It is extremely improbable that any deformity at the extremity of a limb could sur-
vive autotomy, but the experiments to settle this interesting point have yet to be
made. While it would appear that the various deformities which have been described
can not be explained as the results of injuries and the attempted regeneration ot
injured parts, since the limb is usually thrown off in such cases to be completely
renewed or it is retained to be completely restored, yet I can not escape the convic-
tion that the problem is in some way directly concerned with that of regeneration.
The mechanism by which so complete a structure as a limb is regenerated can not be
regarded as simple. As Weismann says, the machinery of a cotton factory can not be
made out of a few simple levers. It is probably exceedingly complex, and it is no
wonder that the parts do not always work harmoniously, that the thread is sometimes
knotted or the product useless,

THE AMERICAN LOBSTER. 149

VARIATIONS IN OTHER ORGANS.
ROSTRUM.

I have met with a single case of bifurcated rostrum, a small male, represented
in figs. 162, 163. The median groove, which corresponds to an area of absorption in
the shell (see p. 88), divides near the apex, each branch going to a terminal spine.
Instead of a single spine below the terminal, there are several smaller ones.

In Alpheus sauleyi the median rostral spine is sometimes wanting, as in the genus
Beteus, of Dana. (See 94, p, 384, plate xx1t, fig. 11.)

OVARY.

Two instances were observed in which the ovarian lobe on one side has suffered
division, one that of a small female (44 mm. long, fig. 131, plate 38) in which one
of the posterior lobes is involved, the other an adult lobster (fig. 164, plate 42) with
similar division of the left anterior lobe.

HERMAPHRODITISM.

A malformed hermaphrodite lobster, Homarus gammarus, was described and fig-
ured by Nicholls in the Philosophical Transactions of the Royal Society of London
in 1730 (141). ‘*The specimen,” he says, ‘if split from head to tail, is female on the
right side and male on the left side.” This was true of both the internal and external
organs. <A similar case of hermaphroditism has been described by Gissler (78) in the
Phyllopod Hubranchipus vernalis.

La Valette St. George (193) discusses a very interesting case of hermaphroditism
which he discovered in the crayfish. He found eggs present in the nearly ripe testis
of Astacus fluviatilis in July and August. The eggs were placed usually at the
periphery of the testis lobe. They were round cr oval, 0.06 min. to 0.015 mm. in diam-
eter, and showed the usual constituents of ovarian eggs. They had a larger germinal
vesicle than the normal egg, were sometimes inclosed in a follicle, and contained yolk
spheres. He asks how the presence of the eggs in the normal testicle is to be explained
and gives the following answer:

These eggs are evidently derived from spermatogonia, which have become unfaithful to their

original functions. Instead of multiplying by division to form a number of spermatocytes, they have
chosen a shorter way, which makes it possible for a single egg to arise from them by simple growth.

Under certain conditions a primitive sperm cell may be converted into an egg
cell, and this, he says, furnishes a new proof of the relation of spermatogonia and
oogonia. Follicle cells may arise from a spermatogonium, but the latter can never
arise from follicle cells.

The spermatogonia, according to La Valette St. George, produce, chiefly by mitosis,
the spermatocytes, which eventually give rise to the spermatids. Spermatosomes, as
well as large follicular nuclei. may be found in the process of degeneration in the testis.

Hermaphroditism has also been described in the Jobster by Hermann (89), who,
according to La Valette St. George, was the first to prove the presence of hermaphro-
ditism in the testes of decapods. Hermann discovered in the anterior parts of the
testis of the lobster large round or oval cells with granular protoplasm, each pos-
sessing a large germinal vesicle with nucleoli. Eight or ten such cells, which were
regarded as undoubted eggs, were found in one specimen. In some of the figures
given by La Valette St. George the ovum fills nearly the entire lumen of the testis.

Chapter X.—STRUCTURE AND DEVELOPMENT OF THE REPRODUCTIVE
ORGANS.

THE FEMALE REPRODUCTIVE ORGANS.

THE OVARY.

In order to understand the structure of the ovary and the changes it undergoes it
is necessary to examine this organ at different stages of development and in the various
phases of the sexual life of the animal. The external eggs borne on the swimmerets
of the female serve as a gauge to determine the age of the developing ovarian ova.

I have already given an account of this organ in my paper on Alpheus (94, see
also 90 and 93) and have illustrated the growth of the eggs. Bumpus (30) has also
devoted considerable attention to this subject and has figured certain structural phases
of the ovary, but the early development of this organ has not been touched upon and
there are important anatomical facts which have not yet been noticed or illustrated.
I shall therefore deal with this subject in detail, though in doing so it will be necessary
to repeat some facts which are already known.

The time of the year when the ovary becomes mature and the size which the
spawning female attains are discussed in other parts of this work.

THE RIPE OVARY.

The ripe ovary, which I will first describe (plate 36, fig. 123), occupies, as we have
seen, the dorsal part of the body cavity. The anterior lobes encircle the stomach, while
the hinder ones extend sometimes as far backward as the fifth abdominal somite.
The ovarian wall, though often quite thick, is very transparent, and the ripe eggs
give it a dark green, beaded appearance. The walls, if mutilated, immediately collapse
and the perfectly ripe eggs flow out in a stream.

The structure of a nearly mature ovary is seen in fig, 141, plate 39. Most conspic-
uous are the massive ova filling the lumen of the thick, tubular wall. Immediately
next to the latter are seen very characteristic structures which I shall call ovarian
glands (0. G.). Immature ova of varying size are interspersed among the glands and
dip down between the ripe peripheral eggs. These structures, together with irregular
blood sinuses (1. 8.) and strands or nodules of muscle and connective tissue, make
up the substance of this organ.

The glands are folds of follicular epithelium similar in origin to that which encap-
sules the larger ova. The long axis of the fold is parallel with the ovarian wall. The
glandular fold consists of a structureless basement membrane and of columnar
epithelial cells (fig. 152, plate 41). The nuclei generally lie at the deeper ends of the
cells, the protoplasm of which is decidedly granular, and cell walls are very indis-
tinct after the ordinary methods of treatment. Occasionally a glandular fold is seen
(plate 41, fig. 153) which has a very different character from the structure just
described. It is expanded into an oval or oblong form, and its epithelial wall appears
in a much disordered state. It is highly vesicular, containing numerous vacuoles,
which probably represent fat globules (/. G.); cell walls are absolutely effaced; nuclei,

150

THE AMERICAN LOBSTER. 151

no longer spheroidal, have become shrunken and scattered about the meshes of a
protoplasmic network. There are, besides, globules (fig. 153, y. s.), probably of an
albuminous nature, which resemble spherules of yolk, and lie either in the lumen
of the fold or are embedded in the protoplasmic reticulum. They are most abundant
in the reticulum, where they sometimes occur as large granular masses. In fig.
145, plate 40, a single large spherule (y. s.) of this kind is seen interpolated between
the follicular cells. A number of nuclei surround it and, however anomalous its
position, the appearance is not artificial. In other cases, where no degenerative
processes are at work, the lumina of these folds are filled with a fine granular residue.
The intimate relations which these structures bear on the one hand to the vascular
sinuses, and on the other to the growing ova, point to their probable function, that of
the formation of yolk. If this is the case, it is evident that the ovarian glands can
play but a minor role in this process. The massive yolk of the ripe egg is formed for
the most part in the protoplasmic reticulum of the egg cell from materials which are
drawn directly from the blood. A third source of the yolk is the follicular cells
themselves, large masses of which pass into the egg at this stage, where they undergo
complete degeneration, as I have pointed out in another paper (93, 94), and shall
describe more fully presently.

THE OVARY AFTER OVULATION.

The appearance of the ovary shortly after egg-laying is represented in plate 38,
fig. 136. It has collapsed from its distended condition, and is now of a yellowish-white
color, flecked with green and orange spots. The green bodies are ripe ova which failed
to be forced out at the time of the last laying. The ducts are often full of them (com-
pare fig. 119). The orange specks are the remains of similar eggs left over from the
previous ovulation. While the latter have thus been in the ovary for at least two
years, they are not yet completely absorbed. The primary membrane of the egg still
remains, inclosing a small disorganized residue (fig. 150).

The structure of an ovary at this period is shown in fig. 139, plate 39. The external
eggs were in an early stage of yolk segmentation, showing that not more than thirty-
six hours had elapsed since the last egg-laying. The ovarian lobe is now a solid mass
of tissue, the youngest ova being disposed about the axis, the older at the periphery.
Irregular blood sinuses penetrate to every part, between folds of follicular epithelium.
These folds take the form of irregular pouches and represent, as Bumpus has shown
(30), invaginations of the ovarian epithelium. This is better seen in Palinurus, or in
the ovary of the adolescent lobster.

The ovarian glands have now attained their greatest prominence, and their relation
to the growing eggs is well illustrated in fig. 139, plate 39, and figs. 151, 152, plate 41.
In fig. 151, from a horizontal section, the eggs lie in strings, or rather tiers, between
the double walls of the epithelial folds, which dip down vertically from the surface of
theovary. Thisis from a later stage than fig. 152, which represents a section through
the central or terminal boundary of the fold. It is from the same ovary as fig. 139,
where the glands are in the ascendant. The glandular cells have the form of tall
columns, the nuclei lying at their deeper ends. Cell boundaries are very vague, the
central ends of the cells merging into what appears as a granular reticulum. The
columnar cells, though apparently stopping short at the sides of the egg, are directly
continuous with the less conspicuous cells of the true follicle. This glandular coxcum
resembles, in section, a narrow bag with an egg pushed into its mouth. A thin layer

152 BULLETIN OF THE UNITED STATES FISH COMMISSION.

of follicular cells, however, screens this particular egg (fig. 152) from the lumen of the
glandular fold. In some cases, however, I have seen the glandular cells in direct
relation with the yolk, with amceboid cells passing into the egg along the line of
contact (plate 40, fig. 149). At this point cells are sometimes seen completely engulfed
in the food yolk. Their nuclei swell to a somewhat larger size, and then speedily
degenerate. Faint ghost-like outlines can be detected for some time; then the
chromatin becomes concentrated about the walls of a gradually dwindling vesicle
(plate 39, fig. 142, Dg.). Finally the chromatin is reduced to very small stainable
fragments. In other cases the chromatin probably breaks up more immediately into
a swarm of minute particles, which remain in the interstices of the yolk spheres in
the peripheral parts of the egg. The “plasmic vesicles” or vacuoles, which Bumpus
(30) has described, are products of the cell degeneration just considered.

Eggs which have been well started on the road of normal growth suddenly go into
a decline and are probably finally absorbed into the blood, somewhat as the follicle
cells are converted into nutriment within the eggs. (See pp. 211-213.) A number of
such degenerating ova are seen to the right of fig. 150, plate 41. They are filled with
refractive globules, which are undoubtedly of an albuminous nature.

After the lapse of from ten to fifteen days after ovulation (the external eggs being
then in the egg-nauplius stage), the ovarian glands have almost wholly disappeared.
The walls of the follicuiar folds, now crowded to the extreme periphery beneath the
ovarian wall, are shrunken and crumpled. At a still later period (attached eggs with
eye pigment, from four to five weeks old) the glands are reduced to shriveled remnants.
Later still, no vestige of them is seen.

STRUCTURE OF THE OVARY AT TIME OF HATCHING OF EXTERNAL EGGS.

When the external eggs are ready to hatch, the ovarian ova have had nearly a
year’s growth. Theappearance of the ovary at this time is shown in fig. 138, plate 38,
and its structure in fig. 147, plate 40. It has a characteristic pea-green color, and the
largest peripheral ova (fig. 133, plate 58) have a diameter which is equal to only one-
tenth that of the mature eggs. The ovarian wall is thinner than in previous stages,
and in the axial portions there are the usual germogenal folds.

Fig. 137 (plate 38) represents the ovary of a lobster taken August 21. An exami.
nation of the external eggs shows that they are about six weeks old. The ovary was
light green, sparingly flecked with yellow. The individual eggs are greenest at the
center, which gives the organ a finely dotted appearance. There isno trace of glands.

The ovaries of “ paper-shells” taken in July, after having produced a brood and
molted during the current season, contain ova which measure fully half the diameter
of the mature egg. This shows that after ovulation and again after the hatching of
the young—that is, during the first, second, and twelfth, thirteenth, and fourteenth
months after egg-extrusion—the ovarian eggs experience their most rapid growth.
(See p. 71, and in particular the description of fig. 138, p. 246.)

At a still later period, when the ovarian eggs have been growing for the space of
nearly two years,' and the ova have attained a diameter which is from 80 to 90 per cent
that of the ripe egg, the organ has the structure seen in fig. 140, plate 39. There may
be considerable variation, but in the specimen from which this drawing was made
(female, taken July 30) the ovarian wall is excessively thin and the lumen is packed full

'This is an estimate Dased u upon athe general facts of aot anal Gesolonment of the ovary, and
not upon the observation of single individuals during this length of time.

THE AMERICAN LOBSTER. 153

of eggs of fairly uniform size. The stromaof germogenal tissue is reduced to a minimiun,
and there is no trace of the ovarian glands which subsequently appear (fig. 141).

The anatomy of the ovary and the slow growth of the ovarian egg, which we have
followed from the time the new eggs were laid during a period of two years, when the
next bateh are ready for extrusion, proves conclusively, as I have pointed out in
earlier papers (93 and 97), that the breeding season of the lobster is not an annual
one, as had been supposed. (See pp. 70-73.)

We have seen in the foregoing account that the massive volk of the eggs is
produced in three ways: (1) It is manufactured in the protoplasm of the growing ovum
from materials absorbed from the blood—the most fruitful source; (2) it is produced
by the activity of the ovarian glands; (3) by the direct absorption of follicular cells.

The fact that parts of the follicular epithelium become differentiated into glands
at a definite period, and that these later become totally obliterated is certainly remark-
able, but I do not see how the phenomena which have been described can receive any
other interpretation. The yolk in Peripatus nove-zealandie is described by Lilian
Sheldon (180) as arising in part from follicle cells. The latter pass into the egg
through the tubular stalk by which this is attached to the ovary, and become converted
into yolk. Yolk is said to originate also in the protoplasm of the ovum, as is commonly
observed in Arthropods; also from the breaking up of a part of the germinal vesicle,
and finally it is produced by certain parts of the ovarian tube itself. The condition
usually found in Platyhelminthes, where there is a permanent yolk-secreting gland,
may thus be compared with that of Peripatus and the lobster, where this function is in
some measure performed by parts of the follicular epithelium.

THE ORIGIN OF THE OVA.

The ova arise from nuclei of the germinal epithelium, as I have described in detail
in a former work (94). The origin of the primary egg membrane from the follicular
cells (fig. 148, plate 40) is well known, but it should be remembered that this chitin-like
envelope is not completed until after the decay of the ovarian glands. Thus, in the
eggs shown in fig. 142, plate 39, and fig. 149, plate 40, there is no membranous boundary
between the yolk and glandular cells.

Cases of the apparent fusion of young ova, mentioned by Bumpus (30), are ocea-
sionally met with, but it seems to me probable that no real fusion ever occurs—the
impingement of cell upon cell often seeming, however, to support. this idea.

THE METAMORPHOSIS OF THE GERMINAL VESICLE.

The very young ovum has a large, rapidly growing germinal vesicle or nucleus,
as shown in fig. 154. At this stage the cell protoplasm forms a thin peripheral zone
having a fine granular appearance in stained sections.

The metamorphosis of the germinal vesicle from this early stage to the perfectly
ripe condition is illustrated by figs. 155 to 161, all of which are drawn to the same
scale. Thenucleolus is formed at a very early period (fig. 154) and is soon vesiculated
(fig. 155). Rarely two or more nucleoli are present (fig. 156); there is usually but one.

The nucleus reaches its largest size (about 4; mm. in diameter) at the close of
the first year after ovulation. It is now regularly oval, its long axes being parallel
with the Jong diameter of the egg (fig. 158). As at an earlier stage, the nucleolus is
vesiculated and almost always found lying close to the nuclear membrane, as if it lad
fallen of its own weight like a shot in a bag.

154 BULLETIN OF THE UNITED STATES FISH COMMISSION.

The nuclear membrane is very distinct up to the time when the ovum approaches
maturity (figs. 159 and 160), when its outlines have become hazy. In the case illus-
trated (fig. 140) the long diameter of the nucleus corresponds with the short diameter
of the egg. The nucleolus and nuclear fluid have undergone a very marked change.
When stained in Kleinenberg’s hemotoxylon, the nucleolus has a hazy, almost
homogeneous, appearance, and stains rather feebly, while the karyoplasm is of the
same character, but takes the stain more feebly still.

When the eggs are ripe and lie free within the ovary ready for extrusion (fig. 141,
plate 39), it is difficult to find the nucleus (partly, no doubt, on account of the great
mass of yolk and the difficulty in cutting it). In one case, where I succeeded, what
appeared to be the metamorphosed nucleus was a somewhat eccentric island of karyo-
plasm (fig. 160; for position in ovum, see fig. 141) without membrane or trace of a
nucleolus. This vesicle stains uniformly, and has a very fine-grained texture. It
has started for the surface of the egg, and in the next stage examined (fig. 161) is in
contact with it. In this particular egg, taken from the oviduct of a female shortly
after ovulation, the cell is dividing, or giving off a polar body; the nucleus has dimin-
ished in size, and no membrane is distinguishable.

THE MOVEMENTS OF THE NUCLEOLUS THROUGH THE ACTION OF GRAVITY.

I have already pointed out the eccentric position of the nucleolus, which is always
observed whenever the immature ovary is sectioned. This was noticed by Bumpus in
1891, but no explanation of the fact was offered. (30, p. 225.)

eee

Cur 18. Cur 19.

Cur 18.—From transverse section of a part of ovary of lobster, hardened with ventral sile uppermost, to show the
effect of gravity upon the nucleolus. From hard-shell lobster which had recently hatched a brood. July 18, 1894.

Cur 19.—From transverse section of a part of same ovary, hardened with dorsal side uppermost, to show the effect of
gravity upon the nucleolus. D, dorsal surface of ovary; ne, nucleus of ovum; nel, nucleolus of ovum; ow, ovarian wall;
V, ventral surface of ovary.

The arrow in each cut shows the direction of the force of gravity.

It seemed very probable that this phenomenon was due to gravity acting directly
upon the nucleolus, which was free to move in every part of the nucleus. A few simple
experiments immediately proved that this was the case. The ovary of a lobster which
had recently hatched a brood was selected and eut into several pieces. These were

then hardened in different positions, in Mayer’s picro-sulphuric acid, with ventral or

THE AMERICAN LOBSTER. 55

dorsal side uppermost or in vertical suspension. ‘This was repeated, and it invariably
followed that the nucleolus fell from its own weight, to the lower side of the nucleus,
like a shot within a tennis ball. This is well illustrated in cuts 18 and 19. The
latter shows in section a part of the ovary hardened in its natural position, with the
dorsal surface uppermost; the nucleoli are here invariably on the lower side, in contact
with the nuclear membrane. In 18, where the part of the ovary was turned bottom
side up, the nucleoli are eccentric, but lie against the opposite side of the nucleus.
Suspend the ovary and kill the tissue in any position you please, the nucleoli sink like
shot in the karyolymph and lie against the lower side of the nucleus. This is true of
all but the smallest ova, in which the nucleolus may or may not so readily respond.
Such eggs sometimes possess two or more nucleoli (fig. 156).

This phenomenon is a direct result of the structure of the nucleus and of the
action of gravity, or else it is an artifact, the result of post-mortem changes. The
nucleus consists of karyolymph, in which float granules of chromatin and other
substances of but slightly less specific gravity, and a single large nucleolus of greater
specific gravity than the surrounding fluids. The chromatophilous substance is
distributed in flocculent masses (figs. 157, 158), which are commonly suspended in the
nuclear fluid, but tend to “sink to the bottom” together with the nucleolus. There is
no trace whatever of a nuclear network in the meshes of which bodies are suspended.

The nucleolus stains very intensely, but is often highly vesiculated, in some cases
forming a hollow shell, owing probably to the extraction of soluble matter by some of
the reagents used. When the nuclear membrane is strongly contracted over any part
of its area (as in fig. 152) it leaves between it and the rest of the egg a regularly
defined space, which is partially filled with a coagulable liquid. This may come partly
or wholly from the nucleus.

I have never seen this phenomenon in the eggs of any other animal. If anyone
have doubts about the facts, a very simple experiment like the one herein described
will be convincing. The explanation which I have offered may, however, be questioned.
I regret that the subject of post-mortem change did not come up for consideration
when I was at the seashore. !

THE RIPE OVUM.

The ripe unfertilized ovum is illustrated by figs. 119 and 141. Those which I have
examined have been taken from the ovary or ducts a few hours or days after ovulation.

The nucleus was in such cases found at or very near the surface of the egg. In
fig. 161, as already mentioned, the nucleus was in karyokinesis. The plane of section
passed through the equatorial plate, so that the poles lie, in reality, above and below
the plane of the paper. This is apparently the division preliminary to the formation
of the first polar body. The rest of the egg is composed of yolk disposed in spherules
of fairly uniform size. A coagulable liquid is usually gathered at the surface, below
the eggshell, where the yolk spheres are here apt to be smaller. There is a single
egg membrane (about 345 mm. in thickness), which is unaltered in the course of the
passage of the egg through the oviduct.

'In regard to this question Professor Bumpus writes me that Bellonci found something very
sunilar in the brain of Squilla, and that this was afterwards explained by Mayer as the result of the
action of reagents, the nucleoli migrating from the killing fluids. Here, however, the action of gravity
certainly plays a part.

156 BULLETIN OF THE UNITED STATES FISH COMMISSION.

THE DEVELOPMENT OF THE REPRODUCTIVE ORGANS.
GENERAL DEVELOPMENT.

In well-advanced embryos taken in January (for stage of development, compare
cut 38) a very minute cluster of cells can be detected on either side of the middle line
close upon the mesodermie partition which screens the heart from the intestine.
These cells are mesoblastic in origin; they possess oval or spherical nuclei which,
however, are not conspicuous for their size. At the time the embryo is about to hatch
there is less doubt in the identification of the reproductive organ (fig. 116, plate 36),
It now consists of a small oval, somewhat flattened mass of cells, lying close upon
the mesentery, next to the intestine. It appears to arise as a proliferation of the
mesoblast of the mesentery, but at this time is very distinct from it.

Later, in the first and second larval stages, the reproductive organ is a more com-
pact, almost spherical, cell mass (about 7; mm. in diameter). Its position, close to the
anterior end of the heart, but in contact with the mesentery, is well shown in fig. 174, ov,
plate 43. It is now differentiated into two kinds of cells: (1) Central cells with large
nuclei; (2) peripheral cells with much smaller nuclei (fig. 117, plate 36). The latter
probably give rise to the ovarian wall, the former to the ova and follicular epithelium.
The clearer central cells contain a distinct reticulum in which masses of chromatin
are held. The organ is delicately suspended to the side of the mesentery by connective
tissue. I did not distinguish the outlines of cells in any part of it.

In as late as the sixth or seventh stages the reproductive organ is still of very
small size and not readily seen.

THE OVARY.

In a female 44 mm. long (No. 2, table 32) the ovary was of the size shown in fig.
131. I did not observe the ducts, probably because of the poor condition of the
specimen when dissected. These were undoubtedly present, since their openings are
visible in the eighth stage (fig. 89, plate 32—No. 3, table 34), when the animal is less
than an inch long. This ovary was 15 mm. long, and each lobe was about one-fourth
mm. in diameter. The anterior lobes embrace the masticatory stomach, and one of
the posterior lobes was branched.

If the condition of the tissue could be trusted—it was preserved in alcohol,
considerably diluted—the organ now consisted of a distinct connective tissue wall and
an inclosed mass of large cells, which are the ova (fig. 146, plate 40). There was no
plaited or folded ovarian epithelium such as we see at a later stage.

In a young female 212 inches long the ovary had the size and appearance shown in
fig. 132. It is about 40 mm. long and has a diameter of 0.5mm. It is opaque white.

In a lobster 4,%. inches in length (No. 42, table 20) the ovary has the same appear-
ance but is somewhat larger. Its structure is now much more complex than at any of
the stages described. It consists of a thin connective tissue envelope and a compact
stroma. Folds of epithelium dip down from the surface and penetrate the interior of
the organ, thus dividing up the outer portions into radial compartments, in which the
larger eggs are seen. These contain large nuclei, with one, fwo, or more nucleoli.
The axis of the ovary lies in a stroma in which all stages in the development of
ova can be traced. Karyokinetic figures of dividing cells are not infrequently seen.
Blood now penetrates to the ovary by sinuses which come in from the wall along
reentrant folds of epithelium.

THE AMERICAN LOBSTER. itayf
THE OVIDUCT.

The oviduct is a straight tube of nearly uniform caliber (figs. 119, 123 od), which
opens to the exterior in a hairy papilla on the coxopodite of the third pair of pereio-
pods. The skin is folded in the mouth of the opening so as to form a valve which
prevents the ingress of water. The appearance of the duct when eggs are passing
out is shown in fig. 119. The ovary had collapsed, but these eggs failed of passage.

The structure of the duct is the same throughout. It has a thin wall of muscular
and connective tissue, and a characteristic epithelium of tall columnar cells. The
latter undergo so marked a change at the period of ovulation that there can be little
doubt that they have some important function to perform. As shown by a comparison
of figs. 167, 168, taken respectively from a lobster just before and just after ovulation,
these cells become very greatly elongated and vesicular. One would infer that they
secrete a liquid which is poured out with the eggs when they are laid. Whether these
cells take any share or not in forming the cement I do not know.

THE SEMINAL RECEPTACLE.

The sternal pouch of the female was noticed and roughly figured by Nicholls in
the Philosophical Transactions of the Royal Society for 1731, but he entertained a
wrong notion of its function. His interesting and unique account of this organ is as
follows (141):

Between the two last legs and the two legs above them there are two processes, which, from their
resembling the nymphie of women, I shall term nymphieform processes. These processes are covered
with hair, and unite at their bases without leaving any passage. * * * The two processes, which
Ihave termed nympheform, in the female make a more obtuse angle at the union of their bases, are
less hairy, and leave a passage, through which it is probable the ova are emitted, to be affixed to the
appendages under the tail.

This remarkable conclusion reached in the last paragraph is unexplained even by
the forced comparisons which were employed.

The observation of Nicholls was forgotten, and the structure which he imper-
feetly described was overlooked until its true function was discovered by Bumpus
in 1891 (30).

The seminal receptacle lies on the under side of the female near the junction of
the thorax with the abdomen. (For its position and general appearance see plate 7, in
which the median slit is clearly shown, and for details, fig. 130, plate 38.) Its paired
wing-like processes, the enlarged sterna of the seventh thoracic segment, are tinged
with bright blue and form, with a wedge-like middle piece belonging to the sternum
of the eighth thoracic segment, a somewhat heart-shaped body. There is a median
slit with elastic edges, and if these are depressed, as Bumpus remarks, a grayish
substance, the spermatic fluid, sometimes oozes out. The middle sternal piece is
prolonged inside the chamber into a stout keel-shaped body strengthened with thick
deposits of chitin, which have a yellowish color and horny consistency. This is sup-
ported by a pair of irregular rods belonging to the endophragmal system, which meet
on the middle line. If the molted shell of a lobster is examined, in place of a solid,
horny keel, a membranous pouch is found. The solid keel-shaped inass is probably
absorbed before a new keel is formed. In the living animal the seminal receptacle 1s
a narrow, irregular cavity.

158 BULLETIN OF THE UNITED STATES FISH COMMISSION.

or

THE DEVELOPMENT OF THE SEMINAL RECEPTACLE.

Development of the seminal receptacle is illustrated by figs. 79, 81, 89, and 98,
plates 32 and 33. Fig. 98 is drawn from the molted skin of the fifth larva. The sex
is not determinable with certainty, but it is highly probable that this is from a male;
the sterna of the sixth to eighth thoracic segments (marked 3-5 in figure) are clearly
defined. The sternal processes of the seventh thoracic segment are fused on the
middle line, where they are distinctly depressed. The unpaired middle piece is
marked as a slight transverse ridge or forwardly directed fold. It is clearly seen
in the sternum of the adult male, where it is not so distinctly wedge-shaped or so
intimately united with the wing-like sterna of the preceding segment. Three suc-
cessive stages in the development of the seminal receptacle are shown in figs. 89, 79,
and 81, plate 32; they are from young lobsters measuring 21.2 mm. (eighth stage,
No. 3, table 34), 35 mm., and 52 mm., respectively. If these are compared with the
condition in an adult lobster (fig. 130) we observe the following external changes:
The sterna of the seventh segment, which are united on the middle line, diverge from
their anterior extremities, forming a wide angle. The sternum of the eighth thoracic
segment consists of a tongue-shaped fold (fig. 81) and a pair of backwardly diverging
rods. The former is constricted off as a single piece, though originally paired, and
develops into the wedge-shaped process seen in the adult organ. It grows forward
into the narrowing angle made by the wing-like process of the preceding sterna. A
secondary cleavage or division of the united sternal pieces of the seventh thoracic
segment is now going on, and the cleft thus formed is the permanent opening of the
seminal chamber. The latter is formed by the approaching walls of the wing-like
folds of the seventh thoracic sternum and tongue-like process derived from the eighth
thoracic sternum.

THE MALE REPRODUCTIVE ORGANS.
TESTIS.

Each testis of the lobster is a grayish white sacculated tube consisting of anterior
and posterior lobes. There is no union between the organs of opposite sides. The
testis of the lobster was figured and described by Milne Edwards, and its structure
has been studied by Grobben (83) and Sabatier (173). According to Grobben, it is
made up of (a) a capsular membrane, (b) tunica propria, and (¢) the spermatogenous
epithelium. Underneath the tunica propria a delicate, structureless membrane was
seen. The epithelium is differentiated into spermatoblasts, from which spermatozoa
are developed, and a syneytium—the Lrsatzkeim—tfrom which new spermatoblasts are
derived. The spermatoblast is regarded as homologous with the egg cell, the Ersatz-
keim with the follicular epithelium. A reserve albuminous material is laid down in the
spermatoblast for use in the development of the sperm cell.

VAS DEFERENS.

The vas deferens or seminal duct is shown as it appears in its natural position on
one side of fig. 120 and when dissected out on the other side. It consists of three fairly
distinct sections: (a) A proximal segment (Zuleitungs-Abschnitt of Grobben), which
serves to conduct the sperm from the testis; a very slender tube of uniform caliber, which
curls, often in an irregular manner, over the posterior lobe of the gastric gland. This
passes very abruptly into the enlarged (b) glandular segment, where the tube bends
backward upon itself. It then turns forward again and, in somewhat the form of the

THE AMERICAN LOBSTER. 159

letter S, passes to the back of the last thoracic leg. The sperm may be traced along
the course of the tube as a central, milk-white, linear mass of closely packed sper-
matozoa. In the glandular segment this is surrounded by a transparent, jelly-like
substance which is secreted by the glandular epithelial cells (spermatophoral glands)
lining this part of the duct. This is gradually constricted into the terminal (¢) muscu-
lar segment, or ductus ejaculatorius, which ends in a valvular opening. A sphincter or
swelling of the muscular layer is seen at the beginning of the ductus ejaculatorius,
serving to force out the sperm.

The two distal segments (b, c) were called the penis or ‘“‘ verge” by Milne Edwards
and Brocchi, because it was supposed that they were evaginated in copulation. It
has been already pointed out that the evagination of these parts is mechanically
impossible, a sufficient reason for dismissing this supposition.

The structure of the different sections of the vas deferens is illustrated by plate
37. The planes of section are marked in fig. 120, 7 to 5. As Grobben has already
shown (83), the vas deferens is surrounded by a distinct membrane and is composed
of a connective tissue wall, inclosing muscles, and a lining epithelium; the latter gives
rise to secretions which mingle with the sperm and surround it with protective envel-
opes. The connective tissue is fenestrated, abounds in blood channels, and the
muscular tissue is disposed into an inner stratum of longitudinal fibers and an outer
layer of circular bundles.

At the extreme proximal end of the duct (fig. 124) the epithelium is apparently
stratified and the wall is thin. The tube is filled with a solid mass of ripe sperm (sp)
and a surrounding coagulable fluid, which is the direct secretion of the epithelial cells.
As the glandular segment is approached the epithelium becomes distinctively col-
umnar (fig. 125). The glandular segment (figs. 127, 128) is partly subdivided by the
infolding of the epithelium (f/). The spermatophores (in some cases there are two) are
restricted to one chamber and are immediately surrounded by a yellowish secretion
_(Spr.), which is probably formed in the proximal segment and stains very feebly in
earmine. The remainder of the spacious cavity (a and bd) is filled with a less dense
coagulable substance which stains freely in carmine. Bodies resembling yolk-spheres
can sometimes be seen.

Grobben says that the secretion of the glandular segment of the vas deferens
of the crayfish appears chalky-white in reflected light and consists of small, shining
granules.

In the ductus ejaculatorius (fig. 126) the muscular coats are strongly developed and
the epithelium appears to secrete an albuminous, granular substance. The height of
the columnar or cylindrical cells varies very much, as Grobben remarks, according as
they are squeezed more or less closely together.

The external opening of the vas deferens is formed by an invagination of the skin,
and according to Grobben is paved with thick cuticle.

SPERMATOPHORES.

The sperm is ejected from the muscular segment of the vas deferens in the form
of spermatophores, which consist of elongated packets of sperm cells, surrounded by
gelatinous capsules, the origin of which we have just seen. The spermatophores can
be pressed out of the ducts when these are removed from the body. They quickly
imbibe water and swell perceptibly when wet with it. The spermatophore is composed
of two distinct secretions, as was first pointed out by Grobben. According to the

160 BULLETIN OF THE UNITED STATES FISH COMMISSION.

same investigator, spermatophores were first seen in Eupagurus by Schwammerdam
in 1752, and were observed in the Brachyura also by Cavolini in 1792. They were
rediscovered by Kolliker in 1841.

SPERM CELLS.

The sperm cells of the lobster were apparently seen for the first time by Valentin,
in September, 1837 (192), 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
immobility of the ‘ rayed cells,” appeared in 1843 (109).

The structure and genesis of the spermatozoa of the lobster have been studied
with much detail by Grobben (83), Gilson (77), Hermann (89), and more recently by
Sabatier (173).

Each sperm cell (fig. 129, plate 37) consists of a cylindrical and partially hollow
column or shaft, surmounted with a rounded dome, on what may be called the superior
end. Between the capital and shaft three long, slender processes are given off, making
an angle of 120° with each other. The processes are sharp-pointed, rigid, and very
slender. The stiffness of the rays has led to the erroneous view that the rayed con-
dition represented an immature stage in the maturation of the cell. The sperm cells
withdrawn from the spermatic receptacle where they have lain weeks or months are
still rayed, although the processes are often broken off or very limp (fig. 129, a).
Apropos to this subject Grobben (83) says:

The stiffness of the rays does not prove that these cells are completely immobile. Moreover,
the observation of Owsjannikow that the rays sometimes draw themselves in, and certain structures
which Ihave examined, enable me to conclude definitely that these rays are living protoplasm and that
they represent amceboid processes, remaining almost in a state of rest. [Compare the observation
of Cano quoted on p. 49.]

The genesis of the sperm cells from the spermatoblasts has been satisfactorily
determined in most particulars, but there are some questions, which concern both this
and the structure of the adult sperm cell, which are still undecided. The conclusion of
Sabatier that the rayed cells become enucleated in the course of their growth can
hardly be accepted. Sabatier has suggested that the stiff rays may serve at first to
stick the cells together.

Nothing is definitely known either as to how the spermatophores are conveyed to
the seminal receptacle or how the spermatozoa reach the eggs and fertilize them.

Chapter X1—THE HABITS OF THE LOBSTER FROM THE TIME OF HATCHING
TO THE PERIOD OF MATURITY.

When the lobster hatches from the egg it is scarcely a third of an inch long. It
rises to the surface, where it leads for a number of weeks a free-swimming, larval life,
totally unlike that of an adult. After the fifth or sixth molt, its larval locomotor organs
having atrophied, it sinks to the bottom, and though now resembling the adult lobster
in outward form it is scarcely more than half an inch in length.

The free-swimming habit of the lobster is characteristic of the first five or six
stages of its existence. In Vineyard Sound and outlying waters we have taken the
swimming stages during the summer months, the latest capture being a fifth larva on
August 28. This period lasts from six to eight weeks, varying slightly with the
season and greatly with the individual. It will be convenient to deal with the habits
of the larve more fully in describing their structure and growth.

From the end of larval life until the later adolescent period the lobster drops out
of sight almost completely. It is a singular fact that the habits of the young lobster,
from 1 to4inches long, have never been well understood. Many fishermen have never
seen a lobster less than 2 or 3 inches in length, although they have fished the greater
part of their lives. Lobsters under 5 inches long pass readily between the slats of the
traps and hence are seldom caught. Rarely, however, one is found clinging to some
part of the gear and is brought up by accident.

Sars in the course of his studies upon the European lobster, traveled along the
coast of Norway from Lurhayn to Bergen, June 19 to August 19, 1875, but was unable
to obtain any young lobsters from an inch to a finger’s length, and says:

So tar as I know, none are found in any museum. I consider it as certain, however, that the
lobster keeps near the coast also during this stage of development. The reason why they can not be
caught with the bottom scraper is partly because of their quick movements, and partly from the
circumstance that they hide among the alg on the bottom of the sea. (176.)

He says that young lobsters 3 to 4 inches long were the smallest known when
he began his studies, and he has nothing to add beyond a description of the first
three larvie.

Spence Bate remarked in 1879 that “common as the European lobster is, it is
very remarkable that a very young specimen has, as far as I know, never been met
with.”! He offered a reward for very young lobsters, but never obtained any less
than 3 inches long.

Ehrenbaum, whose paper was published in 1894, refers to the same uncertainty
which has so long enveloped the history of the lobster from the close of its free-
swimming life until it reaches a length of 4 inches (10 cm.). The smallest lobster
which had been taken at Heligoland up to that time had attained a length of 4.1 em.
The next largest was 7.8 cm. long. He speaks of a collector who, in the course of

‘Report of the British Association for the Advancement of Science, London.

F.C. B. 1895—11 161

162 BULLETIN OF THE UNITED STATES FISH COMMISSION.

thirty years’ experience about Heligoland, had obtained only three lobsters from 3 to
oem. long. (61, p. 285.)

It is evident that the long larval period of the lobster is an important means of

securing a transport from the shore and wide distribution up and down the coast by
means of the tides and ocean currents. As I shall point out in another place, this
transportation is of the utmost importance to the larve, since it is in the bays and
landlocked channels, where the competition among surface-feeding animals is keenest
and destruction of life by animate and inanimate toes by far the greatest.
In consequence of the facts just mentioned, it must often happen that the young
lobster settles to the bottom in depths much exceeding 100 fathoms. What does the
little animal do on reaching its new abode? It probably begins to travel toward the
shore, slowly at first but more rapidly when, in the course of six or eight weeks, it has
become 14 to 15 inches long. Meantime it hides in the crevices of the rocks or conceals
itself under stones whenever danger approaches. Having reached the shore, it estab-
lishes itself in shallow water at the mouth of some estuary or river on the rocky sides
of abay. It lives under stones, or in stone piles, the tops of which are sometimes left
bare at extremely low tides. It can then be found by turning over stones in much
exposed situations, often where the water is not over 1 or 2 inches deep, but where
at the flood there may be from 3 to 5 feet of water or even more. Sometimes several
small lobsters are seen lying under one rock at the same time. While the lobster
is very small, 14 to 24 inches long, it crawls down deep into the piles of loose stones
where no enemy can reach it. After attaining a greater length—of 3 or 4 inches—the
young lobster begins to leave the rock piles and digs for itself a little cave under a
stone. From this protection it stealthily crawls forth in search of its prey, and quickly
returns when an enemy appears. It may take up its abode in the winding chamber of
a deserted conch shell, or in any hole or niche which promises temporary security.

As the lobster increases in size it grows bolder and retires farther from the shore,
although it never loses its instinct for digging and never abandons the usual habit of
concealing itself under stones when the necessity arises.

Little is known about the habits of young lobsters in winter, but it is evident
that they mfust leave the rock piles as soon as ice begins to form, perhaps as early as
December in eastern Maine, and move out, as the adults do, into deeper water. The
casting up of young lobsters on the beach at Woods Hole, in the latter part of January
(see p. 165), proves that they sometimes remain in shallow water even at this season.

The colors of the young lobsters at the time they are from 13 to 2 inches or some-
what more in length are very different from those of the adult. This may be seen by
comparing figures 39 and 22, which represent, respectively, a young male 1.8 inches
long (see No, 22, table 33) and an adult male 10 inches in length. In the young
lobster the general cast of color is a russet or light reddish-brown, which is most pro-
nounced on the sides of the body and under surface of the large claws. The borders
of the carapace and segments of the body and legs are tinged with light Prussian blue.
The upper parts of the body and appendages, especially the first pair of chelipeds, are
spattered and marbled with a dull-bluish pigment. The terga of the abdomen have
often a fine edging of dull bluish-black.

I am fortunate in being able to present a series of plates to illustrate the adoles-
cent as well as the adult stages of the lobster. The original photographs! are in many
cases So > perfect that with the aid of a hand lens the finest details in the sculpturin g

1 These were m ade by ‘the Edmondson Company, ‘of Cleveland, “Ohio.

THE AMERICAN LOBSTER. L6é

of the exoskeleton can be seen. The adolescent forms are all from Casco Bay region,
and are deseribed in table 32. (See also descriptions of figs. 9-18, plates 8-15.) The
smallest: (plate 8, fig. 10, No. 1, table 32) is a male, 1.6 inches long. The right cutting-
claw happens to be much under the normal size, since it is in process of regeneration.
It would probably have attained its normal size after the next molt. The greater
breadth of the “tail” or pleon of the female is not noticeable until at a considerably
later period. Other secondary characteristics, such as the seminal receptacle and
first pair of pleopods in both sexes, are not fully developea until the animal has
reached the length of about 2 inches.

The most striking characteristic of these adolescent stages, in comparison with
the adult form which they so closely resemble, is the large size of the stalked eyes
(plates 8-12). The eye is very much compressed laterally, and in size and shape
resembles that of Penus. The eyes of the adult are relatively much smaller. (See
table 38.) It is therefore possible that the large size of the eyes in the adolescent
stages is an ancestral character. The present lobsters have probably descended
from the Erymoid crustacea which inhabited the seas of the Liassic period. ‘In the
latter part of the Jurassic epoch,” says Huxley (103), “the Astacine type—that of the
modern crayfishes—was already distinct from the Homarine type, though both were
marine.” Hoploparia, which is found in a fossil condition in the Cretaceous and early
Tertiary formations, combines the characteristics of Homarus (Astacus in this work)
and Nethrops. Ihave seen nothing but fragments of this genus figured, but in the
Eryma leptodactylina of Zittel (208) the eyes are relatively quite large, as we see them
in the adolescent lobster at the present time.

Another characteristic of these early stages is the fringe of very long sete on the
caudal fan and the matted tufts of setz about the ends and toothed edges of the
cutting-claw. (See figs. 13-15.)

In a female lobster measuring 32 inches in length (No. 22, table 32) the general
color is a dull reddish-brown. The upper parts are spotted and mottled with darker
brown; the tips of the claws and projecting spines are generally reddish, as in the adult.
A suffusion of light blue is seen, as in younger forms, at the joints of the appendages
and on the edges of the carapace and abdominal terga. This coloration closely resem-
bled that of an adult egg-bearing female which I had at the time. A small male (No.
23, table 32) resembled this female very closely in color. The adolescent period is a
long one, and the gradual development of the pigments of the adult is correspond-
ingly slow. The history of the development of the color of the adult lobster from
that of the larva will be discussed in another place. After this general account of the
period of adolescence, I will now add all the notes which I have gathered that throw
any light upon this important subject. In tables 32 and 33 the history of 63 imma-
ture lobsters, varying from 1.3 to 5.6 inches, is briefly given.

I am indebted to Mr. M. B. Spinney, of Cliffstone, Maine, for a valuable collection
of small lobsters from the shores of Casco Bay and Small Point Harbor, which he has
examined with great care. This collection embraces 36 individuals, 22 of which are
males and 14 females. They were captured mostly in October and November. Mr.
Spinney found young lobsters from 34 to 4 or more inches long in considerable abun-
dance under small stones, where at an extreme low tide there would be but 1 or 2
inches of water; the smallest lobsters were found down among the stone piles, where
the stones were four or five tiers deep. They crawl as far as they can into the laby-
rinthine passages between the stones, and are here secure from every enemy.

164

BULLETIN OF

THE UNITED

STATES FISH COMMISSION.

TABLE 32.— Young lobsters from the vicinity of Casco Bay, Maine.

(Length, 40.3 to 129 mm. or 1.6 to 5.1 inches. |

|
Sex. | Lene | Date of capture. Place of capture. | Remarks.
eee —— i
Male..-.--- 40.3 | | Casco Bay, Small Point, Me. Found in stone piles at very low tide;
Female 44. ve Do.
lester ee) 48 Do.
Ail) Mrcan 52.5 Do.
BSH (aero 58 Do.
pa sescde 62 New Meadows River,6miles | Found ‘under stones at very low tide;
north of Small Point. | _ tops of stones out of water.
Female 64 Casco Bay, Small Point... .. | Under stones and in stone piles at
very low tide.
Male....-.- | New Meadows River...--.-- Do.
Female 68 Basin Bay, east side Mead- | Do.
ows River.
ene Oger 68 Small Point Harbor..-.--..-.--. | Do.
Maletecccs 695) Oct. 9=19 5189322 soc .e2 i iessacseneesentcoseca: Do.
meee Omens We Meets hOMetioe ie serslee|| Merce CON en eee crey eee Do.
Female 73 Small Point Harbor (inner Do.
harbor).
eed One 74 Sept. 26-28, 1893...|..... do | Do.
Male...... 75 Oct. 9-19, 1893. ....|.---- do Do.
Female 75.6 | Sept. 26-28, 1893. ..}..-.- do Do.
Males 2222: SLRON| Seine Coe Aone econo do | Just molted; stomach filled with
| fragments of shells of mollusks, ete.
setley Abas 83.5 | Oct. 9-19, 1893.....)..... (Cinsnaconnesocbesennoabe Found under stones and in stone
! piles at very low tide.
ei hcaoae SaaS oer il) pesssanhason' hades (ca dsucenscbanStoonddss Do.
iy Gadine 85758) eacee (10) Saran acaccecoprbe GW) Saneebetacsacnadecadne Do.
Female 8650 Saas 2 QOvshssnessceewesens OUR capasnpentadascosodss Do.
seat) ceciac I. eemocenosmocmegdacde Basin Baye eemacesseceiee cee Do.
Male..-... 92.3 | Oct. 9-19, 1893..... Small Point Harbor..-.-...-.-. Do.
Ieee Ofeert 93 Opts S03 seceeee paowe do sdhobecsansosescecaanc Do.
| Female O3n4n i Sept.e26—28; 1993 sce ene Onset eee sealer eee teers Do.
amet Core eae 94 Oct.7;1893'—- ~~ 3 - IF NewMeniGus River,8miles | Just molted; stomach filled with
E. of Small Point Harbor. fragmentsof shells of mollusks, ete.
Male:....- 95) yl zeccesecseencoecoce | East side Casco Bay, Phipps- Under stones.
burg, Me.
doe ae 101.5 | Sept. 1, 1893.....-- | Small Point Harbor.......-. Do.
Female 102 | Sept. 26-28, 1893 ...'.--.. (0h), SodoneceooHnsebesboane Do.
prt Otay LO2T4s | Sees dO sects ke eee eee (eesrmenecarosectesuscae Do.
iIMaleeees. | 10455.) Oct 9=1918932 22-10... Ch) PARA Rese nSeeatesantes Do.
sso Oiaerae | 110), Sept: 26-28, 1893: 2.) -- > —- (i coosaesSecesouspoaqsod Do.
edOv=e 2-2 | IOI): se GaspdessBenaSeeceean | Inner harbor, Small Point... Under stones; rostrum imperfect;
| | soft shell.
eee dOlen oe DUO'S Fee Sas sec ere sees Small Point Harbor-.--...--. Rostrum deficient; soft shell.
Female ... 124 Sept. 26-28, 1893...'..... OMe cleceeideceneeein te
Maler-s22: 129 Aug. 31, 1893...--.. , Inner harbor, Small Point-.

PARLE 33. Sete loners Strom Vineyard Sound, Massachusetts, in any of ona Hole.

{ Length, 35 to 142.8 mm. or 1.4 to 5.6 inches. |

Place of capture. |

. Length ; 4
SS ll) ane Date of capture.
Female -: 36 Hatched about
June 20, 1893.
patil 39
Male | 40.5
Female 41
Male. 48
aakikiys 50
-do 52
Female 55. 2
Male. 55.5
Female 60
| Male. . 66.4
..do 74.8
Female 75
Male. .-. 80.3
Female 83.5
Male. 83.7
Female 35
Male.... 36.3
Female 51.8
peor: 69.5 | June 1, 1891
doe 74.6 | June 30, 1891......
Male... 47 July 18,1891
Se domere 92 July 22,1890
Female - LOG235 Seen. dorete=
we dome Wiio) |esdec do eer eee
seed Orme: W208) Ano a OD eee
ee Lower 142.8 July "99. 1891......

Raised

Woods Hole

Remarks.

from egg in hatchery of U.S. F. C.

Station. June 27, 1894, it was 36 mm. long.

It died early in August, 1894.

Hatched and raised at the U.S. F.C. Sta-
tion, Woods Hole, Mass.

Do.

Do.
Woods Hole
Woods Hole Harbor ..| No. 98, table 20.
Por do .....-----.-----| Brought up in lobster pot. (See plate 26.)
Gayalleadetererseseee: No. 43, tabie 20.
Be GO) se eccosccscanbos|| NMP IAN A
Beaor QOmnese eee eee eNOn4outable:20.

Vineyard Sound
Woods Hole Harbor --

Dredged by U.S. F. C. steamer Fish Hawk.
No. 91, table 20.

THE AMERICAN LOBSTER. 165

When the lobsters have attained a length of 34 or 4 inches they become more
bold, leave their burrows among the rock piles, and seek the shelter of stones, beneath
which they excavate a shallow hole. Here they lie concealed from their enemies and
are ready at all times to strike a blow at the smaller and weaker animals which pass
within the reach of their claws.

The young lobsters enumerated in table 33 were captured in or near Vineyard Sound
or raised in the hatchery of the station of the Fish Commission. Fifteen of these
(Nos. 2-16) were collected by Mr. Vinal N. Edwards on Nobska Beach, in Woods Hole,
January 28, 1882, after a hard storm, when there had been much anchor frost. Mr.
Edwards recorded in his journal the finding also of crabs with eggs, thrown upon
the beach, together with isopods, holothurians, sea-anemones, and a large number of
fish, such as cunners, tautog, hake, sculpins, smelt, flatfish, herring, tomcod, and
eels. Mr. Edwards writes that many young lobsters came ashore at the same time on
the point of land where the Fish Commission station is now built. Several years ago,
when small lobsters were used for bait, he used to find them in comparative abun-
dance, from 14 to 3 or 4 inches in length, under stones in shallow water, near Pine
Island, on the north side of ‘‘The Hole.” Some of the stones would be out of the
water at low tide. No small lobsters are found in this place or vicinity at the present
time. Whether this disappearance is due to the general decrease in the number of
lobsters brought about by overfishing or to local changes in the environment, it is dif-
ficult to say. Both influences may be at work. It is possible that owing to warmer
waters inshore, or to other causes operating in summer, the young lobsters are driven
into deeper water, yet they seem to be equally scarce at all seasons. The finding of
small lobsters cast up on the beach in the winter shows, as already pointed out, that
they sometimes remain at this season in comparatively shallow water.

The inspector of fisheries of Prince Edward Island says (209) that lobsters 2 or 3
inches long ‘‘ are occasionally washed ashore after storms and have been found alive
clinging to the meshes of hoop traps.” Lobsters not much over an inch in length are
also said to have been taken from the stomachs of codfish. (See p. 120).

An old lobster fisherman, Mr. Thomas Garrett, at Vinal Haven, Maine, whom I
have already quoted, informed me that he used to see thousands of small lobsters
in the spring, beginning about the Ist of April. He would find them in sounds in
about 20 fathoms of water, on both rocky or sandy bottom. ‘They would ecme up
sticking to the lobster pots, often in considerable numbers, and would average about
14 inches long. He had never seen many lobsters 2 to 3 inches long, probably because
they go so readily through the traps.

I made particular inquiries about the occurrence of young lobsters in the lobster
pound on Vinal Haven Island. The smallest lobsters caught in the pound in 1893 by
seining were about 5 inches long. Half a dozen measuring 8 inches had also been
taken. Small lobsters were noticed in the larger of the two lobster pounds at South-
port, Maine, in March, 1892, and about half a dozen were found from 4 to 6 inches
long. In July and August, 1893, thirty or more lobsters were taken, varying from 3
to 6 inches in length. Lobsters 6 to 8 inches long could be taken in the seine. The
smaller lobsters were discovered by turning over rocks, after partially draining the
pond. None were seen under 2 inches in length. It is possible that some of these
young ones were raised in the pounds, yet it is not certain that this was the case,
since they could readily pass between the iron rods of the fence. The older lobsters,
which are placed in the pounds in very great numbers, would tend to drive out the
smaller ones, whether hatched in these inclosures or not.

166 BULLETIN OF THE UNITED STATES FISH COMMISSION.

An intelligent lobsterman of Rockland, Maine, said that thousands of small
lobsters, an inch long or under, came up on the warps and pots every day while he
was fishing at Hare Island in October and November. The lobsters would tumble off
the traps as they came up. He took one of them home and examined it with a hand
lens, and said that it had the general form and appearance of alobster. The bottom
in that vicinity was muddy or rocky, and covered with seaweed. He had never seen
a 2-inch lobster. The smallest of the young lobsters recorded in table 32 is about an
inch and a half long. These, as we have seen, were taken from the rock piles in the
fall of the year, and most of the lobsters which are hatched in early summer and
survive are more than an inch long by October. Still, this fisherman’s observation
may be correct, and the lobsters seen by him may represent that period between the
sixth larval stage (length 16 mm.) and the smallest of those found in the rock piles.

A small lobster, about 14 inches long, was said to have been taken from the shell
of a living clam in Rockland Harbor not long ago. ‘This was evidently a case of
accidental imprisonment, and the animal may not have been a lobster.

A fisherman at West Jonesport said that he had seen small lobsters brought up
on traps which were set on trawls, in deep water outside, in winter.

Mr. Adolph Nielsen, superintendent of the fisheries of Newfoundland, says that
small lobsters 15 to 2 inches long can be found in shallow water among the “ goose-
grass” in the latter part of Septem ber, and that he has seen lobsters an inch long in
the same situations in the latter part of August and first part of September.

Very few fishermen among many whom I have consulted can give any definite
information about the occurrence of lobsters from 1 to 3 inches long, and probably very
few can discriminate between the young of the lobster and many other crustacea.
Those who have made any observations agree that such young lobsters are very
seldom seen in winter, but are usually found at other times in shallow water, in bays,
harbors, or the mouths of rivers, on rocky (rarely muddy) bottom, where they can be
found by turning over stones at low tide. Mr. George E. Cushman, of Cape Elizabeth,
Maine, says that lobsters 2 to 4 inches long are found in coves and rivers, in eelgrass,
and on sandy bottom, in from 2 feet to 5 fathoms of water.

Mr. Rathbun, of the United States Fish Commission, informs me that hundreds
of lobsters 4 to 6 inches long were captured in the summer of 1880 in Narragansett Bay
by the beam trawl]. The bottom was sandy, and the water 3 to 4 fathoms in depth.

I think it is plain from the foregoing observations that a large number of the ado-
lescent lobsters over 14 inches long seek protected places, such as beds of eelgrass in
shallow water, rocky shores of bays, and the mouths of rivers, where shelter from an
enemy is always at hand; but it is quite likely that some remain in deeper water.

The habits of this animal are molded by its immediate environment and vary to
some extent with the varying elements in the complex of its surroundings.

If we examine the lengths of lobsters described in table 32 we shall find they
form a gradually ascending series, so that when we lay off these lengths as ordinates
upon a horizontal base line, and construct a curve, the latter forms a slightly undulating
ascending line. This means either that the breeding season is indefinite or at least
prolonged, or that the young are extraordinarily unequal in their development. The
number examined is perhaps too small to enable us to draw any conclusions, but it is
a fact, as already shown, that the hatching is not strictly confined to a definite period.
Individual variation in size in a state of nature may, moreover, be considerable.

The interesting question of the age of these adolescent lobsters is considered in
the chapter on the rate of growth of this animal.

s

Chapter XII—THE HISTORY OF THE LARVAL AND EARLY ADOLESCENT
PERIODS.

The transition from the caterpillar to the chrysalis and from this to the winged
butterfly or moth is apparently so sudden that it strikes every one with wonder. This
is, however, deceptive, since changes in the internal organs go on very slowly. The
hard supporting skin of the chrysalis masks the changes which are taking place within.
The young crustacean, on the other hand, has a soft cuticle which is readily cast off; it
thus changes with every molt and in most cases acquires very slowly the external form
and habits of the adult state. It is therefore possible to follow its metamorphosis
step by step. For convenience I shall divide the life-history into three periods—the
larval, adolescent, and adult. The larval period will embrace the free-swimming life,
during which the animal molts five or six times, and the adolescent state the long
interval thereafter before sexual maturity is reached.

The larval history of the lobster is one of exceptional interest and importance,
and must be thoroughly understood before the problem of hatching and rearing the
young can be intelligently discussed, much less solved. I therefore decided, at the
beginning of this work, to devote as much attention as possible to this part of the
subject. This seemed particularly desirable since the individual larval history had
never been traced molt for molt; only four pelagic stages had been described, and the
relations of these were not fully understood. Of the later adolescent period (length
of animal 4 or ? inch to 24 inches) nothing, as we have just seen, was definitely known.

HISTORICAL NOTES.

J. V. Thompson, who was first to establish beyond any doubt the important facet
that the decapod crustacea underwent a metamorphosis after hatching from the egg,
was also the first, so far as I am able to learn, to point out that the European lobster
was no exception to this very general rule. His letter (published in 1835) to the editor
of the Zoological Journal is dated at Cork, December 16, 1830. <A “rough sketch of
the cheliferous member of the larva of the lobster” accompanies this letter. He says:

With regard to the marine species, Astacus marinus or Lobster, I can aver that it actually does
undergo a metamorphosis, but less in degree than any of the above-mentioned genera (Pagurus, Por-
cellana, Galathea, Crangon, Palewmon, etc.), consisting in a change from a cheliferous Schizopode
to a Decapode; in its first stage being what I would call a modified Zoe with afrontal spine, spatulate
tail, and wanting subabdominal fins; in short, such an animal as would never be considered what it
really is were it not obtained by hatching the spawn of the Lobster. (7289.)

Brightwell (24) gave in 1835 a very imperfect description of the young lobster
which he dissected from the egg membranes. He was the first to notice the occur-
rence of double monsters in this species. (See p. 216.)

The embryo of the European lobster when ready to hatch was described by Rathke
in 1840 (159), and a fuller account with figures of the embryo and of some of its append-
ages appeared in 1842 (160). He found lobsters with external eggs in early stages of
development at different times of the year—at the end of May in Christiania, in June
and July at Molde and Christiansund, in September at Gothenburg, and in the first
half of October in Hamburg. He therefore concluded that lobsters either laid their
eggs at different times of the year or that their development was very slow.

167

168 BULLETIN OF THE UNITED STATES FISH COMMISSION.

Kroyer also, in 1842 (170), described with drawings the first larva of the lobster.
In the following year the paper of Erd] was published on the development of the egg of
the lobster (62), in which some good colored drawings of the older embryos are given.

About thirty years later, in 1874, the first circumstantial account of the meta-
morphosis of the European lobster was published by Professor Sars (175). His studies,
however, included only the first three larval stages, and, as he remarked, the changes
which these early larvie undergo, before they reach the adult state, were still unknown.
Some comparisons are drawn in this paper between the first larve of the European
and American species. (For figures of Homarus americanus, see 175, Tab. I, figs. 18-20.)

The first description of the metamorphosis of the American lobster was given by
Professor 8. I. Smith, in 1872 (782), his fuller paper being published in the following
year. He described and figured the first three larval stages and what appeared to be
a fourth or fifth stage from specimens obtained in Vineyard Sound, Massachusetts,
in the summer of 1871. At that time the United States Fish Commission did not
possess the laboratory facilities which afterwards grew out of the labors of Professor
Baird, but notwithstanding these drawbacks this work is so carefully done that sub-
sequent studies will find little to correct, so far as they deal with the external anatomy
of the larvee described. Professor Smith says that between the third stage and what
he called an “early stage of the adult form” ‘“ there is possibly an intermediate form.
The changes in the whole appearance of the animal have been so much greater than
between the first and second or between the second and third larval stages that,
although the difference in size is inconsiderable, the whole change did not perhaps
take place in one molt.”

Professor Ryder, who published a short paper on the metamorphosis of the lobster
in 1886 (771), supposed that the first adult-like form of Smith was preceded by four
stages, but by only three ecdyses, the first molt (which occurs at the time of hatching,
as Sars (175) had found to take place in the European lobster) having been overlooked.
The fact of the case is that the lobster molts four times before reaching the stage in
which it resembles so strikingly the adult animal. It is still essentially a larva in
habit and structure and swims at the surface, although its earlier natatory organs are
reduced to mere rudiments (plate 23).

Figures of the late embryos and of the first larva or its appendages have also been
published by Erd] (62), Couch (48), Gerbe,' and Faxon (67), the work of the latter con-
taining drawings by Stimpson and Alexander Agassiz, but it is not necessary to refer
to these in detail.

METHODS OF STUDYING THE YOUNG.

In the course of my studies on the metamorphosis of the lobster I have endeavored
to follow the history of individual larve. This seems to the inexperienced a very
simple matter, but the task is beset with serious difficulties. We may isolate the deli-
cate larva from its natural enemies and place it under the most favorable conditions
which we can devise, when new foes immediately spring up or unexpected disasters
happen. The larvie which I studied were in most cases hatched at a known period by
the artificial methods now in use. Healthy specimens were then selected and placed,

'The figures of Gerbe are very crude, as reproduced by Blanchard (79) and Dunean. They are
intended to represent the embryo shortly before hatching, the young immediately after hatching, and
after the second molt. The original paper of Gerbe I have not seen.

THE AMERICAN LOBSTER. L659

usually singly, in a 4-gallon glass jar, which was covered with coarse linen scrim and
supplied with running sea water. The mesh of the cloth soon became clogged, thus
fouling the water in the jar, which had to be cleansed daily. Under these conditions
young lobsters have been kept alive over 100 days and carried through ten molts.
The only food which they had beside that contained in the water was lobster eggs.
These were rarely touched by the very young larvie, unless they were floated. Had
my Stay at the seashore been prolonged some of the young could have been kept alive,
I am sure, for an indefinite period, but other duties calling me away before the close
of summer, they usually died from lack of attention.

There is now (August 1, 1894) alive in the hatchery of the Fish Commission sta-
tion a lobster which was hatched from the egg in June, 1893, and which is, therefore,
considerably over a year old.' The length of this lobster is only 36 mm., while three
lobsters which were hatched and kept alive until December 10, 1886, being then between
five and six months old, measured 35, 36.5, and 51.8 mm., respectively. I mention this
fact, now, to show how variable individuals are in their molting or, what amounts to
the same thing, in their rate of growth. It is improbable that such a marked variation
would occur in a state of nature, yet it is likely, as I shall later show, that even here
variation in individual growth is by no means slight. (See table 34 and p. 97.)

Before describing the structure and habits of the larva we will glance at the
condition of the embryo at a late period in embryonic life.

THE EMBRYO IN LATE STAGES OF DEVELOPMENT.

A photograph of a living lobster with external eggs taken in Cleveland, Ohio,
December 8, 15893, is reproduced in plate 7. A cluster of these eggs, showing how they
are attached to one another and to the setie of the swimmerets, is illustrated by fig. 25.
Drawings of the living egg and of the embryo teased from the egg capsule (figs.
26 to 28) give us some idea of the stage of development reached, in this instance, at
the very beginning of winter. Progressive stages of growth in the case of a lobster
whose eggs were laid July 1, 1890, and were beginning to hatch June 1, 1891, are illus-
trated by figures in the text. (Plates G to J.)

At the stage shown in fig. 27 the bright green yolk occupies nearly one entire
hemisphere of the egg. This massive store of food, at the expense of which the organs
of the body are gradually developed, becomes reduced at the time of hatching (fig. 29,
plate 18) to a mere remnant within the stomach of the larva, and often undergoes
changes in color, at the last stage becoming a dull yellowish-brown. The paired com-
pound eyes have already become most conspicuous, both on account of their size and
color. The pigment area, which has a peculiar contour, is almost black when light is
transmitted or when reflected, except at a certain angle. It then glistens with great
brillianey, owing probably to the interference of light in the thin peripheral pigment-
layer. Bright red chromatophores are distributed in a characteristic manner on the
appendages, particularly on their basal segments and along the sides of the carapace.
The yolk is divided by conspicuous dorsal and lateral indentations, corresponding to
the folds of the digestive tract and its diverticula, which gradually inelose it.

During the course of development the ova increase considerably in size and,
losing their original globular form, become distinctly oval or oblong.

1See No. 1, table 33.

170 BULLETIN OF THE UNITED STATES FISH COMMISSION.

Peculiar concretions are developed in the intestine of the embryo when 5 or 6
weeks old, as shown in figure 233, plate 51, and persist up to the time of hatching
(fig. 30, pl. 18). They were noticed as early as 1843 by Erdl (62). We see them to
better advantage in a section of the intestine of a much older embryo, as in figure
253, P. There is great variation in both the size and shape of these bodies, but they
consist of a stainable, apparently structureless core, surrounded by a nonstainable
substance. The latter has distinct concentric striz and resembles the cyst of a para-
site. A concretion teased from the intestine of a similar embryo is illustrated in
figure 256.

In the living animal they have a white lustrous appearance, and are quite conspic-
uous, moving to and fro with the peristaltic contractions of the intestine. On the
suspicion that they might be of a parasitic origin I submitted them to Dr. Stiles of the
United States Bureau of Animal Industry. He has kindly examined them, and con-
cludes, so far as it was possible to reach a conclusion from the material at command,
that the bodies in question were nonparasitic. In this event it is probable that they
are the fecal residue of the egg yolk which undergoes digestion in the course of
embryonic life. The animal is entirely rid of them soon after hatching.

THE HATCHING OF THE LARVA.

A lobster in the act of hatching is represented in fig. 29, plate 18, and one teased
from the egg in fig.30. The embryo at this time is inclosed by three membranes,
namely: (1) the outer or secondary egg membrane; (2) the primary egg membrane,
improperly called the chorion; (3) a larval membrane, which is seen inclosing, like
a glove, the various appendages in fig. 30. These are better shown in a much distended
condition in cut 20, plate F. In this case, nowever, the innermost cuticle is not the
larval membrane, but an earlier embryonic molt, which is absorbed long before the
time of hatching is reached.

When burst by internal pressure the secondary egg membrane splits (in the ver-
tical longitudinal plane of the embryo) into two halves like the cotyledons of a bean,
and is drawn off in most cases over the head by the strand or stalk with which it is
continuous. Itis a thick, translucent bag of a yellowish-brown tint, slightly elastic
and easily torn. It completely separates from the underlying membrane, except at
one point, that beneath the stalk of attachment. Here it adheres to the primary
membrane, which has now become reduced by distention into an exceedingly delicate
pellicle. In this particular case (fig. 29) it was whole, until ruptured by needles (just
above eyes), and thus completely inclosed the exposed parts of the embryo. When
the outer membrane of attachment bursts, it contracts and usually drags the delicate
inner cuticle away with it. The embryo thus slips out in the condition shown in
fig. 30.

This is a very critical period in the life of the artificially hatched lobster. If it is
healthy it soon molts, the swimming hairs are rapidly evaginated, and it emerges into
what may be properly called the first locomotor larval stage. If less fortunate, it lies
on its back for hours, struggling to get clear of some part of its larval covering. The
failure to pass this molt is the cause of death to many embryos which have been reared
successfully up to this point in the hatching jar.

THE AMERICAN LOBSTER. liga
THE FIRST STAGE.

When the lobster has successfully escaped from the egg capsule, and shaken itself
free from its larval cuticle, it emerges as a free-swimming animal, rising to the surface,
where it remains until its pelagic life is over. A sketch of one of these young lobsters
is represented in plate 19, and a lateral view is given in plate 20.

The animal is but little over a third of an mch long. The average length of 15
specimens was 7.84 mm., the extremes being’ 7.50 and 8.03 mm.

The body is segmented as in the adult form, the most striking characteristics
being the enormous compound eyes, the conspicuous rostral spine, the spatulate telson,
and the biramous swimming appendages, which, from their resemblance to the perma-
nent swimming organs of the Schizopods, have given to this and the two succeeding
forms the name of “Schizopod larve.” 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 the organs of
the body—the heart and blood vessels, the alimentary tract, and rudimentary gills—
are seen with 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
gland, the form of which on either side of the body, resembles a cluster of grapes.

VARIATIONS IN COLOR.

The color of the larval lobster is produced, as we have already seen, by a blue
pigment dissolved in the blood plasma and by chromatophores which lie in the dermal
layer of the skin, besides the pigment cells of the eyes. The distribution of the chro-
matophores is very characteristic and it is to these that the brilliant colors of the
larvee are largely due. (See plate 19.) The pigment which they secrete is of two
kinds, bright vermilion and yellow. The red cells are the larger and play the most
prominent role. The expansion and contraction of the chromatophores, by which the
animal becomes brightly colored or pale, ordinarily requires from ten to fifteen minutes
when stimulated by pressure. The chromatophores are distributed in the region of
the carapace, along its sides, and in front of the cervical groove. When they are
contracted the animal is pale blue and very translucent; when expanded the red cells
give it a very decided color. Larve when struggling on the bottom to get free from
their old cuticle or when crippled in any way are usually red, a commonly recognized
symptom of weakness. This, however, does not seem to bean infallible sign. Larvie
which were placed in a pool out of doors on a bright day in June became red ina
few hours while swimming at the surface in apparent vigor. (See p. 188.)

Both the blue pigment of the blood and the yellow and red pigment of the
chromatophores are lipochromogens, which are converted into lipochromes under the
influence of alcohol and other reagents (see pp. 135-136). The stomach and liver are
sometimes bright red, which recalls an observation by MacMunn (132), who coneluded
from spectroscopic evidence that in the lobster (Homarus gammarus) the euterochloro-
phyllof the liver might be carried to the hypodermis and converted into a lipochrome.

G2 BULLETIN OF THE UNITED STATES FISH COMMISSION.
HABITS.

The habits of young lobsters differ but little during the various “stages” of their
free-swimming life, which is spent near the surface. Their pugnacious instinet is
undoubtedly strongest immediately after hatching, when their activity in killing and
devouring one another invariably attracts the notice of the spectator and forms an
insurmountable barrier to raising them in small aquaria. Like the young of most
pelagic organisms, they can not bear crowding, either in vertical or horizontal limits.
As Weldon and Fowler (201) have remarked:

They must, if they are to thrive, have a large superficial range, as well as a considerable depth
of water in which they may sink when such conditions as light and heat demand it.

In swimming the larve use both the exopodites of the thoracic limbs, by the beating
movements of which they are impelled upward and forward, and the abdomen, by
the contraction of which, with its broad telson-plate, they dart rapidly backward.
Each thoracic limb consists of a short stalk, with two diverging branches, the outer
branch, which serves as an oar, being flattened and fringed with long feathered hairs.
The oars or exopodites work independently of the inner branches, which are mainly
prehensile organs, and alone give rise to the adult imb. The exopodites atrophy and
disappear completely after the fifth stage. In the common swimming or floating
position at the surface the thorax is usually held in a horizontal position, with bent
abdomen. In rising the head is inclined downward, often with the “tail” uppermost.
When too weak to keep at the surface, they vacillate over the bottom, standing on their
head, as if probing for food, which, however, is not the case.

The larve appear to be quite hardy under certain conditions. Thus I have kept
them alive, and apparently healthy, in small flat dishes of sea water, without change,
for from one to four days at a time, or until they molted to the second stage.

The time which elapses between two successive molts varies, as at all subsequent
stages, with the supply of food and general condition of the animal. In the larvee
which I had under observation the first stage lasts from one to four or five days, the
healthier ones molting in the shorter period.

THE SECOND STAGE.

All the larve of this stage which I have examined were raised from the egg.
The average length in forty-seven cases was 9.2mm., the extremes being 8.3 to 10.2mm.
It is evident that some of these were undersized, and the measurement of this stage
given by Professor Smith, 10.6, is greater than any which I have observed. His speci-
mens were all taken by the towing net, and if the number examined was sufficiently
large it would indicate that under natural conditions a greater size is attained.

A profile view of the second larva is given in plate 21. This is drawn to the same
seale as the first larva on plate 20, and illustrates the increase in size effected at
the second molt. All parts are now much larger, excepting the swimming thoracic
appendages, which have grown but little. The swimmerets, visible as buds below the
cuticle of the first larva, have now grown out on the second to fifth abdominal somites,
and the rudiments of the last pair of appendages can be seen beneath the skin at the
proximal end of the telson plate (fig. 102, plate 34).

The habits of the second larva differ in no respect from those of the first, and in
color the two stages are very similar. In transparent larve, with contracted chroma-

HE AMERICAN LOBSTER. 173

tophores, great variety may be produced by the color of the gastric gland, which is
often orange or some cast of yellow, and by the contents of the alimentary tract, which
shows plainly through the body walls. Bright green pigment now appears for the first
time upon the dorsal surface of the carapace and upon the tergal surfaces of the first
five abdominal somites.

As in the first stage, the larvie thrive only on one another when kept in close quar.
ters. I have often watched one of these larvie as it attacked another which appeared
to be its equal in size and strength. The aggressive lobster usually tried to seize
his fellow by the small of the back or between the carapace and abdomen, using for
weapons the walking appendages, chiefly the first three pairs. He was soon astride
the back of his victim, and dragged him to the bottom of the jar, where he began to
devour him.

The second larval stage lasts from two to five days.

THE THIRD STAGE.

The average length of the third larva in seventy-nine individuals examined was
11.1 mm., the extremes being 10 to 12 mm.

The third larva resembles the preceding stages very closely in habits. Struc-
turally, it differs but little from the second larva. (Compare plates 21 and 22.) The
outer branches of the thoracic legs are still the principal swimming organs. However,
the last pair of abdominal appendages, which form the outer blades of the tail-fan,
are ready for service, and the swimmerets are fringed with short sete. The large
claws, which were already conspicuous, are relatively much larger.

COLOR.

The third larva resembles the preceding stages closely in color. When the chro-
matophores close the animal is quite pale, as was the case with one which | examined
in the act of molting. As arule, the color is enhanced by this stimulus. When this
specimen was examined with the microscope it was seen that the red chromatophores
were contracted so as to resemble small dots or stipple marks. The yellow pigment
cells were more irregular.

When this transparent, almost colorless, larva is placed in a dish with others the
contrast is very striking. The colored form, in which the pigment cells are expanded,
is a rich, deep brown, varied with a vivid yellowish-green. The appendages are for
the most part reddish-brown, excepting the terminal parts of the smaller ones, such
as the exopodites and endopodites of the pleopods and the flagella of the antenni,
which are bluish. The large chelzw are a deep reddish-brown. The same color occurs
sparingly on the sides of the carapace and on the lateral and ventral surfaces of the
abdomen. The hinder parts of the carapace are touched with bright yellowish-green,
as are the third, fourth, and fifth terga of the abdomen. These intense metallic
colors greatly resemble those of the fourth larva. In reflected light a whitish pigment
is seen in the lateral eye, which is strongly iridescent, as in the earlier larvee.

One larva (10.8 mm. long) has the thorax and upper half of the abdomen greenish-
blue; abdomen reddish below; tail-fan reddish; red pigment cells occur on the append-
ages and on the sides of the branchiostegites, as in the earlier stages.

In another, examined in the act of molting, on July 3, the colors were very bright.
Especially noticeable were the metallic green spots on the fourth and fifth abdominal
segments.

174 BULLETIN OF THE UNITED STATES FISH COMMISSION.

Another larva (11 mm. long) has colors similar to the first just described: Large
chele reddish-brown; lower half of the abdomen, caudal fan, and sixth abdominal seg-
nent of same color; carapace yellowish-green, rather less transparent than in earlier
stages; bright peacock-green with yellowish tinge on the terga of the fourth and fifth
abdominal segments; considerable blue at the joints of the appendages (probably
because the cuticle is here thinner) and in different parts of the body. It must be
remembered that the transparency of the larva is now determined in an important
degree by the greater or less time which has elapsed since the last molt—that is, by the
greater or less proximity to the ecdysis which is to follow. The old cuticle becomes
partially opaque as soon as any lime is deposited in it, which happens at about this
period.

The third larval stage lasts from two to eight days.

THE FOURTH STAGE.

The young larva! emerges from its fourth molt into a form which bears such a
striking resemblance to the adult lobster that an intervening stage between this and
the preceding was supposed to exist; but such is not the case. A dorsal view, colored
to life, of one of these larve is represented by plate 23. The swimming branches of
its thoracic legs have been abruptly shed, or rather have been reduced to functionless
stumps (plate 31, figs. 74,75). It still swims at the surface, with greater agility and
speed than at any former stage, and is still virtually a larva, although it has the adult
locomotor organs.

It swims rapidly forward by means of the swimmerets, and darts backward
with quick jerks of the abdomen, ‘“ frequently jumping out of the water in this way,”
as Professor Smith says, “like shrimp, which their movements in the water much
resemble” (182). As they move forward they hold the large chel extended straight
in front of the head; when disturbed they raise the chele to defend themselves like
an adult lobster.

It has the larval rostrum and the large antennal scale or exopodite, and the
first abdominal somite is without trace of appendages.

The average length of 64 larvee was 12.6 mm., or about half an inch, the extremes
being 11 and 14 mm.

COLOR.

The range of variation in color is now very great. A typical color pattern is rep-
resented in plate 23. Occasionally, even at this period, a larva is very light-colored
and its transparency is nearly equal to that of the third larva.

The cast of color may be (1) yellow and red; (2) red; (3) green; (4) green and
reddish-brown. In the first case the carapace is light vellow, translucent, and sprinkled
with red chromatophores. The abdomen and large chele 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 chele. 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

'The use of the word “‘larya” for the fourth and fifth stages is not without objection, but it is
perhaps better than the phrase ‘‘adult-like form.” It is very probable, as I have shown, that the
young lobster may remain at the surface of the ocean, even after the sixth molt. It will be most
convenient, however, to define the larval period of the animal by the duration of its pelagic life,
which is practically at a close by the end of the fifth stage.

THE AMERICAN LOBSTER. 1 (c3)

ereen. Bright yellow-green areas are noticeable on the abdominal terga as before, and
upon the hinder portion of the carapace. There is some brown pigment on the large
chele and tail-fan. In the fourth variety (fig. 36), the abdomen and chele 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 carapace is
ereenish-brown. In this and all earlier stages the color of the carapace is partly due
to that of the internal organs, especially to the alimentary tract and gastric glands.

The following notes illustrate the changes which individual larvee undergo, with
reference to molting and surrounding conditions. A fourth larva raised from the egg,
when examined on July 13, was decidedly bluish. The whole animal was quite trans-
lucent, the heart and yellowish “liver” showing plainly through the shell. The claws
and body were sky-blue, due, as in the first larva, to the blood pigment. The brown
and yellow chromatophores were contracted to such an extent as to have no appreciable
effect upon the general color pattern. Two days later the carapace was greenish and
the chele dark brown. On July 17 the colors were deeper; on the 19th the general
cast of color was dark bluish-green; reddish-brown on the abdomen and chele. On
July 21, when the animal was nearly ready to molt, the carapace was bluish-green, the
abdomen and chele brownish-red. Four days later, July 25, this animal molted to the
fifth stage. The fifth larva was dark olive, tinged with brown on the abdomen and chelie.

A larva which molted July 11 to the fourth stage was pale, and apparently
almost devoid of pigment. The internal organs were plainly visible. There was a
delicate wash of brown on the abdomen, tail-fan, and chele. The microscope showed
that the closed chromatophores were very small.

Another larva, 13.1 mm. long, which was raised from the egg, had on July 6 the
usual mixture of brown and green pigments. On July 15 the animal was very dark
brown, excepting the carapace, which had a metallic green luster. The large chelie
are tipped with white or cream color, and there is a large light patch on the outer side
of the hinder end of the exopodite of the uropod. Fainter and smaller whitish areas
occur on the pleura of the first abdominal ring. This larva molted about August 3 to
the fifth stage; color, reddish-brown.

Rarely is a larva seen which is reddish-orange, the blue and brown pigments
being almost completely obscured. The pigments of the eye are similar to those of
the earlier stages.

Ina larvaof 14 mm. long, observed July 25, the carapace was of the usual greenish-
brown cast, with three light-greenish spots on each side—a very small spot behind
the eye, a smaller one below this, and a larger one farther back below the cervical
groove. These are the first traces of very characteristic areas, which I shall call
“tendon marks,” upon the skeleton of all later stages, and mark the places where
certain muscles are attached to the integument. The significance of these color
changes will be considered later on. (See p. 135.)

A fourth larva, which was caught at the surface near the Fish Commission wharf
on avery bright day (July 25, 1891), was similar in color to some of those already
described. The thorax was green, brightest posteriorly; the chele and abdomen dark
reddish-brown; a brilliant light-green area appeared on the tergum of the third and
fourth abdominal segments.

On August 10 I examined a number of lobsters in the fourth, fifth, and sixth
stages, which had been kept in glass jars and fed upon meat. Many of these were so

176 BULLETIN OF THE UNITED STATES FISH COMMISSION.

completely covered with foreign matter that they could hardly swim, some lying upon
their backs on the bottom of the aquarium. Colonies of zoothamnium-like protozoa
were clustered over all their appendages. The setze were loaded with sediment filled
with bacteria, diatoms, and infusoria. This illustrates the fate which awaits the larvie
of all crustacea, when crowded in small aquaria.

The fourth larval stage lasted (in the average of nine individuals, which were
raised from the egg) 13 days and varied from 10 to 19 days.

THE FIFTH STAGE.

In fifteen individuals known to have molted five times, the average length was
14.2 mm., and the extremes 13.4 and 15 mm.

There are no external marks by which the fifth stage can be distinguished from
the fourth or even from the sixth stage with any degree of precision, at least by the
unaided eye (fig. 31, plate 18). Neither the size nor color changes can be invariably
relied upon. Microscopical examination, however, shows that the rudiments of the
swimming exopodites, which could be readily detected in the fourth larva, have now
become still more reduced, while in the sixth stage they have completely disappeared.

The following notes illustrate the changes of color which are observed in larvee
passing from the fourth to the fifth and sixth stages. On July 7 a fourth larva
(No, 35, table 34) showed the typical colors, reddish-brown and various tints of green.
When observed eight days later the color was dark maroon. The fifth molt occurred
about July 17 (length, 14.8 mm.). The color was then greenish-brown; the large
chele reddish-brown, tipped with cream color, most marked upon the propodi. As
in some fourth larve, there is a terminal light spot on the exopodite of the uropod.
Faint light spots are also seen on the sides of the abdominal segments. There are,
moreover, two very prominent, white, discoidal areas on the carapace corresponding to
the insertions of muscles, as already pointed out.

The following measurements of this larva will give a clearer idea of the length
of some of the parts and of their increase after the molt:

Millime-

Measurements of larva, third to fifth stages. Teves

Leng thiofstheitthiarvarccesemccoesseee eee eeee eeeeeese: eee
Distance from tip of extended chelipeds to end of telson.....--.---.--
Length of flagellum of second antenna.-..-......--.--.--...----------
Length of carapace in third stage ......-...--..------------------
Length of carapace in fourth stage .......--------------.----.----
Length of carapace im fifth stage. .....-..--....---..-.------..--- 56
Greatest width of carapace, fifth stage.......--.-..------.------------
Length of largeichele, fourth stage:<.\- -----\- 22 == sclseilesemanioeee ice
Length-of largeichelx fifth statemanas. sssceeees eee eee eee eee eee |

Bee

WR YIAAES

Be We CO

Another larva raised from the third stage (No. 12, table 34) is olive-green, with
the characteristic white marks very faint on the carapace. The large chele are
yellowish-green, due to the presence of blue and yellow chromatophores.

In the case of a fifth larva reared in an aquarium the colors resemble those of
the sixth stage, represented in plate 25. The white spots on the carapace have the
disposition shown in fig. 37, plate 24. The third pair of maxillipeds are tipped with
white.

No noticeable differentiation can be detected in the large claws unless occasioned
by loss and subsequent growth or by injury to one of the members. It often happens

— i -“— —

Increase |\ereere | Increase . Increase :
Length. in Increase. | Seventh Length. in Increase. mie nth Length. in Increase. ate Leng
length. } 3 length. "7 length. 2
a= : | = is =
mm. mm. Per cent. mm. mm. Per cent. mm, mm, Per cent. mm
15.5 13 9.1 Aug. 20 18.4 2.9 18.7 Sept. 10 21.2 2218 15. 2
Mi}G) |cbeeecossellooseoooniod July 27 19.5 3 18.2 Aug. 14 22.6
}
|
14 15.3 3 9.3
22 16 2 14.3
se 16.8 | 5
15 16 1 6.7
Soe 16.6 1.6 10.7
10 16.5 2.2 15.4
21 17 2 13.3
25 UES eocscncagssasasacsce | July 25 18 IE 10. 4 Aug. 8 21 3 TON TA | tee ences | eee
| |
|
®Sept.22]} 19.75| 4.75 | |
-|| Aug. 13 21.2 2.7 14.6 | Aug. 23 25
adodaadcr |ssocsesees eosSesened Seacoasaae Aug. 1} 24
i] |
eee 20.99| 2.83 TAG WEocacsanecl| Oe
| } |
9, plate 32. 3 Accurate within 0.2 to 0.9 mm. 4¥Por colored sketch of this lobster in sixth sta

Tirst
molt,

_ a a r
a « j
j
;
i
TABLE 34.—Record of molts of larval and adolescent stages. '
{ _ Increase ls { Inerease || a - Increase © | lScrerease a | Tncrease | lg Increase e | Increase &; Tnereas' S pA 5 -
| Incr Second : Third Fourth ' vifth eat Sixth i ; Seventh ; Kighth Renee Ninth moxease 1 Tnerense
Length. | in i Length, in Tncrease, Length m Increase.) Age. Length. in Tnerease.| Age. Length. in Increase.) Age. Length. in Tnerease. Length. in Tnerease, 12) Length. Tne 4 mth | Length. i Tenth
_ ON, length. Pemolts |e | ength: | molt. © "| Jength. BOs “length. ey oallhs © | length. mE Selita le pee el ean, Pe) uae: #U | Tout walt, | Bength. | a ‘|Increase.

Per cent.

min.

duly 7
saith 8

June 30
saiWise--
peedOeeee|
July 4

u

Peet Ommes

July 2
Jnly 3
duly 4
July 6
July 7

July 6
ara 4

SSeem oso
Buses

poaluceey|

mm.

Per cent.

mm.
July 18 thy!
July 17 | 2

July 13

July 20
July 16

July 17
July 19

July 8
aay 9

July 11

July 13
duly 6
| July 25
-| July 4
July 8

duly 9
July 8
July 11
July 6
July 15

We) Asa LI Net

SRae

12,65 |

per cent of stages, 13.67; of individuals, 13.89 (omitting No. 38, ninth stage).

of hatching of lobsters Nos. 16-36 is only approximate.

* For colors of this lobster in sixth stage see plate 24: Ventral view of thorax, eighth stage, shown in fig.

Per cent.
11.7

1.2 I 8

Per cent.
16.4

mm, Days.

a 38
-|?Aug. 2
July 13

July 14
July 22
eect) aoe

July 15
---d0--..

July
July

1.48 11.53 -

16,12

mm.

Per cent.

Der cent.

3.68 | 18.76

0, plate 32,

*Accurate within 0.2 to 0.9 mm.

Sept. 10
Aug. 14

Ang. 8

Sept. 22
Aug. i

20.99

mm,

2.8

2.83 |

Per cent.

mm.

mm,

14.6) Ang. 23
Aug. 1
15.5 .

‘For colored sketch of this lobster in sixth sta

vy eM,

Paci

toon
ah

0

THE AMERICAN LOBSTER. NER

that the dactyl is bent upward as much as forty degrees away from the propodus, so
that the cutting edges meet but imperfectly.

Larva No. 36, table 34, was nearly ready to molt to the fifth stage on July 17. It
was of an opaque greenish-brown color, the claws deep brown. The carapace had a
dull, bluish luster when strong light was reflected from it, a well-recognized mark of
the molting state.

Two days later it was in the fifth stage. The carapace and upper surfaces of the
abdomen were now greenish: brown. ‘The white tendon mark on the side of the cara-
pace below the cervical groove was very prominent. The light areas on the first
abdominal ring and upon the uropods were rather faint, and the chel, as usual, were
tipped with cream color.

The remarkable “ death-feigning habit,” which I shall discuss later, was developed
in this larva to an unusual degree. A colored drawing of this lobster after the sixth
molt, which occurred about July 30, is represented in plate 25,

The fifth larval stage lasted in five observed cases from 11 to 18 days.

HE SIXTH STAGE.

The average length of five iobsters known to have molted six times was 16 mm.,
the extremes being 15 and 17 mm.

I have already referred to the color of this stage, which is represented in an indi-
vidual raised from the egg on plate 25. The general cast of color of the upper parts
is often dark green or greenish-brown, and the ‘“‘tendon-marks” on the carapace have
now become very conspicuous. Equally characteristic are the snow-white pleura of
the first abdominal ring.

A dorsal view of another lobster of this stage is given on plate 24. The coloring
is from the sixth stage of larva No. 3, table 34. The whole animal is of a reddish-
chocolate color, against which the white spots contrast very sharply. In the cervical
groove there is a narrow transverse white area, a large white spot on the distal
extremity of the meros of the cheliped, in addition to those already mentioned and
the flattened rostrum is couspicuous for its absence of color, being but faintly tinged
with green.

A young lobster captured with the tow net in Woods Hole Harbor in the day-
time, August 23, 1890, resembles the sixth stage, already described. The length of
the lobster was 16.5 mm. (For record of the capture of other lobsters in sixth stage,
see table on p. 187.)

The individual color-changes which these lobsters undergo were well illustrated in
a specimen, 16 mm. long, captured in the net July 24, 1890. When first taken it was
bright bluish-green, excepting a slight amount of brownish pigment visible on some
of the appendages. This lobster was accidentally left over night in a glass dish of
water on my work-table. In the morning it had a decided reddish-brown color and
was very weak. One is reminded of the similar but more striking change in color
which the remarkable little lizard Anolis princeps, of the Southern States, undergoes
when it is suddenly stimulated.

Larvie have also been captured in the tow, from 15 to 16 mm. long, which resembled

more nearly the fourth stage in color, but undoubtedly belonged to the fifth and sixth
stages. ‘
F. C. B. 1895—12

178 BULLETIN OF THE UNITED STATES FISH COMMISSION.

A young lobster about six weeks old, raised from the egg, and probably in the
sixth stage, was light brownish-olive on the upper surface, the chele being more
decidedly brown. The under surface of the body was almost colorless. The usual
cream-colored or white spots occurred on the carapace and appendages and the ter-
minal spines of the abdominal pleura were whitish. The large claws, which show no
special differentiation, are held together in front of the animal as it swims forward.
When suddenly disturbed, the young lobster opens its claws, spreads wide its arm-
like chelipeds, at the same time raising itself into a threatening attitude, ready to
receive or strike a blow. The iridescent pigment of the eyes is no longer visible.
Some measurements of parts of this lobster are as follows:

| Millime-

Measurements. | ters.

ee ue
Iben ge thieaeecce sce e eee ate e eee eet ere ete es ee ete erl| 16
hengthrofthorax, including rostrumer-e-e eee oriele in-ear eee 8
Greatest wwidthiof thorax: 232 2s. -m = pacer ne ate sees nieaseer | 4
bene th of antennary fagellumee.. jee eee see eee eee eee ree 11

Hength’ of propodusiot large chela: mays ssscenees seen a cen eeeee 5.5

Lobsters in the fifth stage, which are raised in aquaria, swim less at the surface
than in preceding stages, going frequently to the bottom of the jars for their food, and it
is during this and partly in the sixth stage that the pelagic life of the lobster comes
toan end. It then sinks to the bottom and leads an entirely new life. Its larval
characters have completely disappeared, and buds of the modified appendages of the
first abdominal segment have begun to grow out. In locomotion and general habits it
resembles the adult animal closely, but the final adult condition is only attained after
a long series of molts, which require, in all probability, from four to five years.

The sixth stage lasted (in three cases observed) 9, 14, and 18 days, respectively.

SEVENTH STAGE.

The seventh stage can not be distinguished by any known characteristics from
that which immediately precedes and follows. Unless one has watched and recorded
the molts, it is impossible to say at this or a later period through just how many
ecdyses the animal has actually passed. The larval stages merge insensibly into
those of the adolescent period, and these pass as gradually into those of the adult, so
it will be more profitable to follow the history of individual lobsters from this period
onward rather than to attempt to describe stages which have no marked distinguishing
characters.

In table 34 I have recorded the molts of thirty-nine young lobsters raised during
the summers of 1891 and 1892. The increase at each ecdysis and the increase per cent
(that is, the ratio between the actual increase and the former length) are also given.
Many of the adolescent lobsters, which it should be understood are the remnant of a
much larger number which I attempted to raise, died shortly after the last recorded
molt. Some, however, were living when I was obliged to leave Woods Hole, at the
middle or latter part of August, and doubtless could have been reared had they
received the necessary care. The life-history, as illustrated in table 34, has been
followed from the time of hatching to the tenth stage or eecdysis, when the animal
is over an inch long and about three months old. i

We have considered in detail at the close of Chapter m1 the bearings of these
observations upon the rate of growth in the lobster.

THE AMERICAN LOBSTER. 179
DESCRIPTION OF SMALL LOBSTERS.

The number of molts or the rapidity of growth is a question which now assumes
special interest and, as I shall eventually show, it is subject to considerable individual
variation.

Two young lobsters after the seventh molt measured 18.4 and 19.5 mm. (Nos. 1, 2,
table 35) and remained in this stage 21 and 18 days respectively.

Lobster No. 1 (table 55).—The first of these was raised from the fourth stage. Its
color in the sixth stage is represented on plate 24. The animal after the seventh molt
was light brown, tinged with green, when observed on August 20. It exhibited the
“ death-feigning habit” in a very marked degree. This lobster molted for the eighth
time on September 10, and died the day following, when it measured 21.2 mm. It was
hatched about May 27, and was therefore 107 days old.

Lobster No. 2 (table 35).—This young female lobster had just molted when first
examined on July 15, and was then without doubt in the sixth stage. In color it
closely resembled fig. 37, plate 24. It molted for the seventh time on July 27, when it
attained a length of 19.5 mm. The color at this time was but little changed, being
a deep chocolate above, with the tendon marks on the carapace equally prominent.

The triangular rostrum is somewhat narrower. The ‘“ tinger” of the large claw
and the outer branch of the tail-fan are cream-colored. The latter, as in the sixth
Stage, carries a very long fringe of setze, which becomes characteristic of the adolescent
period. These sete are about two-thirds the length of the uropod. The left cheliped,
which was thrown off at the time of the sixth molt, had grown out again, so that after
the seventh ecdysis the length of the new appendage was about seven-tenths of that
on the opposite side. The length of the right chela was 6.5 mm.; of the left, 4.5 mm.

The stalked eyes are now very large and continue to grow relatively faster than
the rest of the body until they attain great prominence in the adolescent stages, as
already described.

The first pair of abdominal appendages are present as small buds, and after the
next molt their size is not greatly increased.

After the eighth molt (August 14, length 22.6 mm.) there was but little noticeable
change in color. The general cast is still brown, with a bluish-green tinge on the
carapace. The length of the fringing set of tail fan—1$ mm.—nearly equals that of
the telson. The median sternal spines are present on the second to fifth abdominal
somites, and have a bluish color.

Lobster No. 3 (table 35).—This young female lobster was raised from the egg and
placed under observation when in the third stage, July 4, 1892. At this time it was
11 mm.long. It molted to the sixth stage on August 13, and when I finally left Woods
Hole on the 23d of this month there had been no noteworthy change. When examined
on September 22, by Dr. E. A. Andrews, it had attained the length of 19.75 mm. It is
therefore highly probable that only one intervening molt had occurred and that this
happened late in August or early in the following month. It died before another
ecdysis, on the 5th of October, when it was about 105 days old, having molted eight
times.

Lobster No. 4 (table 35).— When this lobster came under systematic observation,
on the 25th of July, it was in the sixth stage and 16.5 mm Jong. An account of its
ecdyses, which were carefully watched, one occurring on that very day while in a dish
upon my table, will be given in another place. (See p. 183.)

180 BULLETIN OF THE UNITED STATES FISH COMMISSION.

Before molting the animal was of a dark umber color and very sluggish. Imme-
diately after this ecdysis (the seventh in number) the whole body was translucent, the
general color being reddish-brown, with a slight greenish tinge on the carapace. The
large claws were a bright terra-cotta color. There was a prominent whitish crescentic
spot immediately behind the cervical groove and the three characteristic tendon marks
oneach side of the carapace were as prominent as in the sixth stage. (Compare plate
24,) The pleura of the first abdominal somite were snow-white, and the uropods of the
tail-fan were tipped with cream color,

The lobster after the seventh molt keeps steadily upon the bottom, in walking
over which it uses chiefly the last three pairs of thoracic legs. The large claws and
smaller chelate legs next to them are extended forward in front of the head, although
the latter appendages are occasionally used for locomotion. A very slight differentia-
tion in the large chele is noticed, but in the eighth stage the difference is marked.
At about the time of the seventh ecdysis the right antennary flagellum was lost;
eight days later it appeared, in the process of regeneration, as a short spiral coil;
this continued to grow, and after the eighth molt, which occurred on the 8th of
August—an interval of two weeks from the last—it was about its normal size.

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
the color pattern becomes more and more complex. In the eighth stage the general
color is deep reddish-brown, with olive tints. The characteristic tendon marks and
cream-colored spots are present. There is a dorsal light-green median stripe on the
carapace, very much narrower than when first seen in the fourth stage.

This lobster had undergone no appreciable change by the 25d of August, but
when next examined, September 22, it measured 29.5 mm. In the interval of thirty
days it had undoubtedly molted twice and was in the tenthstage. The first abdominal
somite has very delicate, white appendages, which are distinctly two-jointed and raised
from the surface to a nearly vertical position.

Lobster No. 5 (table 35).—This lobster was hatched about May 25, and when
isolated, on August 1, it measured 24mm. It was probably in the ninth stage and was
about 67 days old. The general color was dark green, touched with brown; large
chele olive-brown, reddening toward the extremities, with glistening white tips; the
under side was a tint lighter. The uropods and telson are whitish, bordered with
reddish-brown. The contents of the intestine can be seen through the slightly trans-
lucent shell. Tendon marks on the carapace are prominent, as in the other cases
described.

Some measurements of this lobster are as follows:

nr |
Measurements of lobster No. 5, in ninth stage. Pee:
en gth ss oo e coco ete e sen tine ee meen cre ease er elena ieee stetceretts 24
Tength offcarapacese--cecene eee cereeeecte eee eee eee pense eecees 11
Greatest widthiot, carapace merc seeceece ete eee eleerettetelelntetersieie star 5
Lengthiofsanténnary) flagellum ees 2eee =~ eerste eee eee eee 23
Length of large chela on either side..--.--.-- 9
Greatest breadth of chela of one side. -.-.-.--- 3
| Greatest breadth of chela of other side 2.5

In the smaller of the two claws the extremities are nearly straight; in the larger
the “fingers” are more bent, and each bears a large tubercle at about the middle of
the occludent margins,

THE AMERICAN LOBSTER. 181

The animal hides among the stones at the bottom of the aquarium, and behaves
in most respects like an adult animal. The eyes are dull brownish-black, without
iridescence,

When examined again on August 13 this lobster had molted, now for the tenth
time, and was 25 min. long. ‘The general color was dark brownish-green, with
reddish-brown on the large chelipeds, as before. The white or light color of the
pleura of the first abdominal segment and tail-fan is »bscured or has disappe wed.
The shell pigments are now more abundant, and the cuticle has lost its translucency
in consequence.

The following measurements illustrate the growth of some of the parts:

1)
Measurements of lobster No. 5,in tenth | Millime- |) Measurements of lobster No.5, in tenth Millime
stage. ters. | stage. ters. |
ene theermeene ee eeee cine eos 28 Length of cutting chela.............-. 11
length) Of carapace... -..---------...-. 13 | Greatest breadth of cutting chela -... 3
Greatest width of carapace..-....----- 6.4 Length of dactyl of cutting chela..--. | 5a
Length from tips of extended cheli- | EE AOU EO Noo seobace conesansesoon 4
peds to end of telson.....-..-.:..--. 34 Breadthyoftelson\ss--m-lse c= 2-5 == bass |
Length of antennary flagellum. .....-- 20 | Length of terminal fringe of hairs... 2
Length of antennal exopodite. -.--.--- 5.5 Greatest width of abdomen at second
Length of crushing chela -.........--. 10.5 SWihiG) 5 Sok ac pce cacosaqhanSpEcseasce 5
Greatest breadth of crushing chela-.. 3.5 eng thro firostrumeesec--ce sas. «= ane 4
Length of dactyl of crushing chela- -. 5 | Breadth of rostrum at base .--...-.--- | 2

Lobster No. 6 (table 35).—This was the only survivor out of a considerable number
of lobsters hatched early in the season of 1892, and when first examined—about the
first week in August—measured 18.5 mm., and was probably in the seventh stage. At
this time a slight difference in the large claws could be detected, which increased
with subsequent molts. There is nothing noteworthy in which this young lobster
differed from those already described. (See No. 38, table 34.)

Lobster No. 1 (table 33).—I have referred to this young female lobster, which was
hatched about June 20, 1893, and was alive when I left Woods Hole, August 6, 1894.
It was therefore 412 days old, and allowing it to have attained the length of 28 mm.
at the tenth molt—the average length of three individuals known to have reached
this stage—it must have molted thirteen times, which I am confident is not far from the
truth. It is probable that no molts occurred during the winter, the last two recorded
having taken place May 21 and June 18, 1894.

The brilliant color is now wholly due to the pigments of the shell, which is no
longer transparent, and the color pattern is so complicated that it almost baffles deserip-
tion. The body is light umber, freely speckled and mottled with darker shades. The
appendages are reddish-brown and slightly translucent. Small light areas or suftu-
sions are scattered over the body. The tendon marks on the carapace corresponding
to those seen in the fifth and sixth stages are prominent, that below the cervical groove
being over a millimeter in diameter. The pleura of the first abdominal ring are snowy
white. The free edges of the segments of the body and appendages are bright blue.
The large chele are tipped with white. The openings of the oviducts are clearly
seen and the copulatory pouch is not yet closed. The color of the appendages on
the under side is light reddish-brown. ‘The tail-fan is of the same hue edged with
deep red. The claws, which are tufted with sete at their tips, show remarkably
little differentiation. The eyes have a dark-purplish pigment and have acquired the
characteristic large size and prominence of the adolescent stages.

182 BULLETIN OF THE UNITED STATES FISH COMMISSION.

The following measurements show the proportions of some of the parts:

Measurements. Mane: Measurements. | Milling.

2] |

| Length, June 27, 1894-..- <2. 36 | Length of left chela (propodus) .-.---.| 13
| Mengthiof carapace:--2-.2--se-% soe 16.5 || Greatest breadth of chela (propodus)-. 3.6 |
Greatest breadth of carapace .-.-..-.- 7.9 engthiotidactylea-esqesse ec e eee 7.8 |
Length of antennary flagellum. .------- 33 | Weng thiotitelsoneestenseeee eee eres 5 |
Length of right chela (propodus) ---. 13.5 || Breadth of telson at base..-.-..-.---.- chal |
Greatest breadth of chela.......------ 4 Length of fringing setw..-.....-.--.-- 2 |

i) Wengthiof idactyliererecrs sees ceee 7 Diameter of cornea of lateral eye...... 2 |
|

This lobster was kept in a small glass aquarium, and fed with clams and with
lobster and cod eggs. It was undoubtedly undersized for its age, having molted about
fifteen times.

The three lobsters raised in 1886, which on December 10 measured 35, 36.3, and
51.8 mm., respectively (Nos. 7, 8,9, table 35), had probably molted twelve times in the
first two instances and fifteen times in the last.

Lobster No. 10 (table 35).—When this young lobster was brought up accidentally
on a lobster pot in Woods Hole Harbor July 18, 1891, it measured only 47 mm. (See
colored drawing, plate 26.) If it was hatched in the summer season it must have
been a little over a year old, and it is very probable that in this case also there had
been fifteen molts.

The youngest lobsters taken in Casco Bay, Maine, October, 1893 (Nos. 1, 2, table
32), were doubtless hatched in the previous June, and were therefore about 16 weeks
old. They had probably passed from thirteen to fourteen molts.

It is, therefore, clear that the young lobster varies very considerably in its rate of
growth, whether under artificial or natural conditions. In a state of nature the young
lobsters hatched in June are probably from 2 to 3 inches long when 1 year old. (See
pp. 96-99.)

Twill now add a tabular statement of the successive molts of the adolescent lob-
sters, whose development has just been considered. Further details of their history
are given in table 34.

TABLE 35.—Successive molts of young lobsters and their measurements in millimeters.

Number of molt. Date of 4
No. of lobster Ea Agean
: aa = say measure-| days.
1| 2 | 3 4 | 5 6 7 8 9) LOM | pala! 12 | 13 | 14 15 ment.
— — | - —
1 (No.3, table 34)..|...|...|..-- 13 | VERE TERE PAO Wee callecocedlsscalbeoaos alk aoe Sept. 11 | 107
Da(Nox4stable;s4)ioa| ser | (me cea eee eet ICE EY SG EPPS ON Nemseclloserca| soca lsasood|S6ocoodallsacsoc Aug. 14 79
3 (No. 37, table 34) -|..-|---| 1d j'12.5 | 13.4] 15 2507.05 | ELON O metres | otrecaeect| eratetal| ettecetera | Meetetel| obetetel tetera Oct. 5 105
4 (No. 34, table 34) .|..-|..- | BSHabocoed leoneos 16.3 18 21 Hedy || PAB eee locoons Bool brisdllansase Sept. 22 94
Ba(iNiossontable.o4)m ome see enee |e omeer loaecud|secesel| Gacnosslcoscact 49 D8 ia ee | eee eile eral aeateac Aug. 13 80
GK(NO538;table:34) = 2.4). 2|5 25'S 2 ce eee sta] sess om LOION POD) econ | BOON OR eres eee S8c6|loosu|boo00 Sept. 22 294
ia Nomliiatable;23)2|oacleschecccleae ell eer ee ees | eerie eee Seon loceses Bee ba) ecnd|pocel reetes Dec. 10} 2173
BH(NOwBstable 23) 5 |e.) be -|sct sl eee | ee mere | eee ees esas S elsenaee 55/23 6830) eee lena ees dormer mls
(ONG, 1G) TEN PEs Rae ee cleeed leceeoe locestallccdcon|booccs: eee ac | cet | center Baodlgasaas =ee[-==|20108 |o-d0)----|) 2178
10 (No. 22, table 23).|...!..- Pee eee a | ea eaeees [bane sce SesSaceleees coeese ee sleeecee meee eee 2 47 July 18} 2390
| | | } \
1 Approximate. 2 Number of molts, length, or age estimated.

THE MOLTING OF THE EMBRYO AND LARVA.

The first cuticular structure formed in the egg is a delicate blastodermiec mem-
brane, which appears in the later stages of yolk segmentation and has often been
erroneously considered to belong primarily to the ovum. It becomes so firmly glued

THE AMERICAN LOBSTER. 183

to the primary egg-membrane that any attempt at its removal almost inevitably results
in stripping off the blastoderm with it. It is, however, soon absorbed, or at least
detached, so that in the early egg-nauplius stages the shelling of the egg is quite an
easy matter, yet when the egg-nauplius is fully developed the inner layer of the
capsule invariably sticks to the tips of the antenne, which are usually torn off with
its complete removal.

Ata stage closely following the egg-nauplius the embryo is inclosed by three dis-
tinct membranes. I think it probable that the delicate inner cuticle, which can now
be removed by the aid of hot water without injury to the parts, is a distinct structure
from the blastodermie membrane just mentioned. The appendages at this time are
gloved with a cuticular molt, evidently distinct from that which comes off with the egg-
capsule when the animal is hatched. When eye pigment is formed these envelopes
are very easily demonstrated, as seen in cut 20, plate F, where they have been distended
by the prolonged action of picro-sulphurie acid. Up to this time it is therefore probable
thatat least three embryonic molts have occurred. Others follow during the long embry-
onic life, and, as I have already shown, when the animal is about to hatch it is inclosed
in a cuticular molt which must be shed before it can enter upon its larval career.

In the second molt, preceding the second larval stage, the delicate shell is cast
entire, the only break being, as in the later stages, along the margins of the inner fold
of the carapace—that is, in the epimeral region of the branchial cavities and next
the abdomen. The shed cuticula is transparent, colorless, and flexible, and contains
little or no Lime. The abdomen is usually withdrawn last, as 1s the case in adult life.

The cast shell at the fourth molt, which precedes the fourth stage, contains a
little lime, but no pigment. The fifth ecdysis, which ushers in the fifth stage, is
more noteworthy. A larva of this period molted in a glass dish on my table in the
forenoon of July 13, 1892, and was soon attacked by others in the dish and killed. The
carapace is gradually elevated from behind, and the animal escapes through the open-
ing thus formed. The calcareous shell, which is of a beautiful light-blue color, retains
its shape perfectly. The carapace, as early as the fourth stage, has a characteristic
areolation (see figs. 113 and 115, plate 35) and is covered with short setz. There is a
wide median stripe or band of absorption which branches into the cervical groove on
either side and widens at the rostrum. The carapace can be easily split along this
thin unpigmented area.

The ecdysis of a lobster in the sixth stage, the color of which has already been
described (No. 354, table 54), was observed under similar circumstances. On the 8th of
August this lobster molted again while I was watching it. At about 9.50 a. m., when
first examined, the abdomen was drawn away from the thorax, showing a distended
pink membrane which connects these parts of the shell. Fifteen minutes later the
carapace was elevated, the pressure of the inclosed body swelling out the mem-
branes slowly. At 10.24 a.m. the young lobster turned over on its side and in three
minutes was out of its shell, about an hour having elapsed from the moment when
the process, already begun, was observed. The eyes and cephalo-thoracic appendages
are withdrawn first, and when these are free the animal slips away from the old shell,
the abdomen coming out last, as in the adult lobster.

The color of the cast shell is blue, with some green and brown pigment on the
tergal surfaces. Pigment is now gradually deposited in the outer calcified layer of the

184 BULLETIN OF THE UNITED STATES FISH COMMISSION.

shell, which soon becomes wholly responsible for the color of the animal. The dorsal
median stripe of the carapace is much narrower than when first observed in the fourth
stage (fig. 115), and the areas of absorption of lime salts from the lower segments
(meros and ischium) of the large chelipeds are clearly outlined. The molting and
growth of the adult animal are fully discussed in Chapter Ir.

COLOR VARIATIONS IN THE YOUNG LOBSTER.

In the description of the larval stages just given I have purposely dwelt upon the
color changes which the young animal undergoes. This is intended to supplement
the previous observations upon the color variations of the adult. To sum up these
detailed accounts, we find that the color of the first four larval stages is subject to
considerable individual variation, due to the transparency of the shell and the con-
tractility of the chromatophores which lie beneath it. In the first larva the pigment
cells are relatively few, and respond to the slightest stimulus. With the growth of
the animal they become very numerous, more differentiated, and so commingled that
a very varied color pattern results. It is probable that in these stages their chief role
is a physiological one. A transparent and almost colorless larva swimming at the
surface of the ocean would undoubtedly be safer than a brilliantly colored one, but the
indiscriminate destruction of these larve is so great, both on the part of animate!
and inanimate foes, that such protection would count for little. That it really counts
for nothing 1s shown by the fact that the fourth larva (also a pelagic animal) is almost
invariably richly colored and is far more conspicuous at the surface than it would be if
colorless. Again, it is not likely that larvee know any such thing as fear, and the
chromatophores appear to expand under any unusual stimulus.

The color variations of the larva are the expression of physical and chemical
changes taking place in the body, as the result, for the most part, of physiological
conditions. Some of these changes are sudden or discontinuous, and have no adaptive
or protective significance.

After the fourth molt pigment begins to appear in the chitinous shell and a com-
plicated color pattern is gradually produced which, as I have already shown, has, in all
probability, a protective value. This happens when the young animal has given up
its pelagic life and lives upon the sea bottom, having essentially the characters of
the full-grown mature form.

The color variations of the adult are discussed in Chapter VII.

THE DEATH-FEIGNING HABIT.

It was a matter of no little surprise to find that young lobsters in the fourth and
fifth stages sometimes exhibit in a striking degree the remarkable phenomenon known
as “feigning death.” It is not strictly a habit, since it does not appear in all larve.
Some display it upon the least provocation, the greater number but seldom or not
at all. I have observed the same thing in a lobster over a year old, but have seen no
trace of it in the adult.

A young lobster to which I have already referred (No. 36, table 34) when examined
two days after the fifth molt showed this peculiarity in a typical way. When stroked
lightly with the finger it would immediately stiffen, and lie stretched out at the bottom

' Such as herring, mackerel, and menhaden, which from their peculiar habits of straining water
for food can hardly fail to be great destroyers of crustacean larvie. (See note on menhaden, p. 122.)

THE AMERICAN LOBSTER. 185

of the dish, on its side or back, as if paralyzed. Its appearance is now, however,
very different from that of a dead animal. The large chelipeds are stretched forward
in front of the head, and the other thoracic legs are drawn after them and held close
together with their tips pointing forward. It usually remained in this position from a
quarter of a minute to a minute, when it would slowly orient itself and begin to move
about, in a short time becoming very active. This lobster on one occasion remained
in this stiffened, apparently paralyzed condition for the space of eight minutes, and
would have continued in it a longer time still had it not been aroused.

While lying at the bottom of the dish in this state, a convulsive movement
of the swimmerets was detected and a twitching of various muscles over the body.
The appendages sometimes quivered, as if the muscles were in tetanic contraction. The
chelipeds and other walking legs remained perfectly rigid. When the animal finally
recovered, the thoracic appendages were gradually relaxed and, putting itself in a
defensive attitude, it slowly swam off.

If water is squirted at it with a pipette it will sometimes roll over and immedi-
ately straighten out as if dead. When disturbed and treated roughly with the finger
or a penholder, it stiffens in the same way; the abdomen is bent up slightly; all the
appendages are straightened out; the swimmerets are bent backward and can be seen
to quiver; the beating of the scaphognathite does not cease.

I have no doubt that this phenomenon is strictly analogous to the “ shamming
death” of insects, but itis neither a habit nor an instinct. It is, perhaps, the raw
material, so to speak, out of which useful instincts are developed in some animals.
According to Darwin, there is great variation in the degree in which this instinct is
manifested ininsects. He observed ‘a most perfect series, even within the same genus
(Curculio and Chrysomela), from species which feign only for a second and sometimes
imperfectly, still moving their antenne (as with some Histers), and which will not
feign a second time however much irritated, to other species which, according to De
Geer, may be cruelly roasted at a slow fire, without the slightest movement—to others,
again, which will long remain motionless, as much as twenty-three minutes, as I find
with Chrysomela spartii.” In seventeen different species which he observed, including
an Iulus, a Spider, and Oniscus, ‘“‘both poor and first-rate shammers,” he found that
“in no one instance was the attitude exactly the same, and in several instances the atti-
tudes of the feigners and of the really dead were as unlike as they possibly could be.” !

Romanes, in his Mental Evolution in Animals, has treated the subject of feigning
‘death very fully, and has collected some very interesting facts. Two observations
upon the crustacea are quoted, one of Bingley upon the ‘*common crab, which, when
it apprehends danger, will lie as if dead, waiting for an opportunity to sink itself into
the sand, keeping only its eyes above it,” and one by Preyer, who is said to have made
crayfish ‘“‘stand upon their heads while in the hypnotic state”! Romanes agrees with
Preyer in attributing the shamming death in insects to ‘‘kataplexy,” or mesmeric sleep
(in many cases the physiological effect of fear), but gives some remarkable cases among
vertebrates in which it seems almost equally probable that there is intentional purpose
to deceive.

The “shamming dead” in insects and crustacea which leads simply to quiescence,
and thus to their becoming conspicuous in the presence of their enemies, had been

‘Chapter on Instinct written for The Origin of Species. See Appendix to Mental Evolution
in Animals, by George John Romanes, p. 364.

186 BULLETIN OF THE UNITED STATES FISH COMMISSION.

intensified, as Darwin believed, through the agency of natural selection. Itis evident
that no such instinct could thus arise in pelagic animals, where the cessation of the
natural movements through hypnotic or other influences would lead to vertical down-
ward motion by the action of gravity, unless such inovements were of decided benefit.

It may be significant that the phenomenon is seen for the first time in the lobster
when it is about ready to sink to the bottom and assume the adult habits. I have not
examined a sufficiently large number of the adolescent lobsters, from 14 to 3 inches
long, to say how commonly they exhibit this peculiarity. I believe, however, that it is
in this case a sporadic phenomenon, which has not at present become a habit. It is
not easy to see, moreover, how, in the environment of these animals, where so many
of their enemies are scavengers or omnivorous, it could be of much service. to its
possessor when finally established on the bottom.

THE FOOD OF THE LARVA.

The food of the larval lobster must necessarily consist for the most part of minute
pelagic organisms, such as copepods and crustacean larvee. When watched in con-
finement they may now and then be seen giving chase to copepods, sometimes larger
than themselves, and often without success.

The young lobster, however, shows little discrimination in its food. It seems to
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 larvie vegetable fibers, the scale of a
moth or butterfly, and fine granules of sand.

On June 17, 1893, I examined the stomachs of a number of larve (raised in
aquaria) 13 to 14 mm. long, probably in the fourth and fifth stages, and found them to
contain the following substances: (1) diatoms in abundance, chiefly Navicula and the
long tangled ribbons of Tabelaria; (2) remains of crustacea, probably parts of young
lobsters; (3) bacteria in large numbers; (4) cotton and linen fibers and parts of alge;
(5) amorphous matter, with sand grains. The sediment of the jar contained the same
species of diatoms in abundance, and amorphous débris similar to that found in the
stomach and intestine.

The stomach of a larva captured in Vineyard Sound August 12 (length 15 mm.)
contained the following organisms: (1) parts of crustacea; (2) diatoms; (3) shreds of
alge. In another young lobster taken at the same time (length 17 mm.) there were
(1) parts of crustacea, (2) large numbers of diatoms, (3) filaments of green alge and
thin sheets or shreds of vegetable tissue, (4) the scale of a lepidopterous insect, (5)
bacteria, (6) amorphous matter in large masses.

Messrs. Weldon and Fowler (207) came to the following conclusions after experi-
menting with different kinds of food which were thought might be acceptable to the
larvee:

It was definitely concluded from these experiments that whatever food is used must be floating in
the condition of small particles at a short distance below the surface, 7. ¢., in the same position as the
natural pelagic food of the laryie of the sea, whether this consist of Copepoda, other Decapod larvie,
trochospheres, fish ova, or other members of the pelagic fauna, As to the other two forms of food tried,
the Noctilucee were apparently eaten, the shrimp larve (Mysis stage) certainly were attacked, and
from the fact that the young lobsters attack and devour each other it is probable that Decapod larve

form at any rate part of the usual food. The contents of a tow net taken near the Eddystone on
August 6, which held a young lobster, consisted chiefly of Megalops and Mysis stages of Decapoda.

THE AMERICAN LOBSTER. 187

The yolk of hard-boiled eggs, crushed crab, boiled liver, tow-net material, noctilucie,
copepoda, and live shrimp larvie, were all partially, but none absolutely, successful as
a food supply.

The self-destructiveness of the young lobsters when too closely crowded in aquaria
has already been referred to. When one lobster attacks another under these con-
ditions the pursuer usually endeavors to get astride of his victim and nip into the
abdomen at its junction with the carapace with its sharp-pointed prehensile legs.
When the object is too heavy to float, such as the egg or larva of the lobster, they
frequently go to the bottom; but if the animal is healthy it will be usually seen swim-
ming about the aquarium dragging its prey with it and feeding upon it as it goes.

HELIOTROPISM OF LARVAL LOBSTERS.

During the past six summers which I have spent at Woods Hole, 1589-1894, I have
been struck with the scarcity of the larvie of the lobster in the waters of Vineyard
Sound. The tow net has been frequently used both by day and night, and I have
made many unsuccessful trips in search of young lobsters in the season when one
would expect them to be common. Thus, on July 11, 1891, | towed all around Gay
Head, a mile beyond the Devils Bridge buoy, and in Vineyard Sound. We found
only copepods, sagitta, young fish, and fish eggs. The day was bright and the water
had been calm for two days. The prevailing winds had been from the northeast. At
Menemsha we obtained one lobster with eggs hatching out, but the fishermen reported
_that very few lobsters with old eggs were then taken; that is to say, the hatching
season was about over.

I had a similar experience on July 16. The water was smooth; the wind had
been southwesterly for four or five days. There was very little surface material, a
few barnacles, megalops and sagittas.

The following is a list of all the lobsters taken at the surface of the ocean during
the six seasons mentioned—the capture was made in the daytime unless otherwise
stated :

Date. | Observations. |

July 9, 1889 ; One lobster (fourth or fifth stage) at surface of harbor.
July 8,1890} One lobster, length 15 mm.; captured with tov net, in harbor, in the evening.
July 9,1890 | Fivelobsters, 15 to 16mm.long; takenby R. P. Bigelow aboard the Grampus, at station 32.* |
July 16,1890 | Two lobsters in sixth stage, 16 mm. long; taken with dip net close to wharf of U.S. Fish
Commission Station.
| July 24,1890} One lobster, 16 mm. long; taken with tow net in harbor.
| July 28, 1890 | One lobster, 15 mm. long; taken with tow net in harbor.

Aug. 23, 1890 | One lobster, 16.5 mm. long; taken with tow net in harbor.

July 1,1891)| One lobster in sixth stage, 18 mm. long; taken at surface 7 miles southwest of No Man's
Land.
June 29, 1892 | One lobster in third larval stage; taken at surface, near wharf. |
| June 29, 1892 | One lobster in fourth larval stage; taken at surface near wharf. |
| Aug. 15,1892 | Young lobsters, probably in fifth and sixth stages, seen at surface of Vineyard Sound by
Protessor Libbey. |

|
|
|
|

* Location, latitude 41° N., longitude 71° 9’ W. Observations made by Professor Libbey, July 12, 1890,
10.47a.m. Surface temperature 63.8° F.; bottom temperature, 54.1° F.

Larve in the first stage have been taken in Vineyard Sound as early as June 3.
Lobsters in the fourth stage were captured by Vinal N. Edwards, August 12, 1887.
Young lobsters (stages not determined) were also taken by him in Woods Hole Harbor,
Vineyard Sound, and in the vicinity of Gay Head, in the month of July, 1888.

188 BULLETIN OF THE UNITED STATES FISH COMMISSION.

Surface towing was done at the following places in the same year without obtain-
ing any lobsters: August 1, 17, and 18, Vineyard Sound; August 23, off Cuttyhunk;
August 27, 30, 31, Woods Hole Harbor.

Professor S. I. Smith says of the young lobsters which he obtained in Vineyard
Sound in the summer of 1871, that numerous specimens ‘‘were mostly taken at the
surface in the daytime, either with the towing or hand net” (182). Of the older pelagic
stages he says:

They appear to live a large part of the time at the surface, as in the earlier stages, and were often
seen Swimming about among the surface animals. They were frequently taken from the 8th to the 28th
of July, and very likely occur much later.!

We know that lobsters are now far less abundant around the Elizabeth Islands
than they were twenty years ago, and we should expect to find that the young had
diminished in a proportionate degree. Millions of larvee, however, must still be
hatched in Vineyard Sound and adjacent waters every year. What then becomes of
them? I believe that they are eaten up by surface-feeding animals, principally fish,
or meet their death from indiscriminate causes. The tides tend to disperse the young
over a wide area, thus carrying them to and from the shores. Horizontal distribution
alone would not account for the extreme scarcity of the young in Vineyard Sound at
the present time. If, however, there were a corresponding vertical distribution, the
conclusion which we have reached would not be warranted. It thus becomes a matter
of much interest to determine the heliotropism of the larvae, or the law which governs
their vertical movements in the water. :

The results of my observations and experiments with larve lead me to conclude
that the young, free-swimming lobster usually displays what Loeb has called positive
heliotropism (725)—that is, it tends to swim toward the light or near the surface in the
daytime. The conclusion therefore which we stated above, that the absence or extreme
scarcity of young lobsters in a region where the adults still abound is due to their destruc-
tion, is supported by experimental testimony. The bearing of this fact upon the artificial
propagation of lobsters I have discussed in an earlier paper (see 97).

I will add a few notes upon the experiments which were made to test the helio-
tropism of these larvae.

Experiment 1.—On June 27, 1894, I placed about 25,000 young lobsters, in the first
larval stage, in the observation pool at the Fish Commission Station, to watch their
behavior. The sun was intermittently obscured by clouds during the greater part
of the forenoon. When liberated, the larvae formed a large cluster near the surface,
where they remained for a short time. Then all went down to a distance of from 1

follows: ‘‘All the larvee captured in Vineyard Sound and neighborhood in 1871, on which my papers
were based, were taken in the ‘daytime.’ My notes usually give only ‘day,’ or ‘evening’ for time
of capture, but the larvee of my first and second stages, taken July 1, are marked ‘forenoon.’
Since 1871 I have many records of first and second stages taken in the ‘day’ and, as far as I can find
now, only two cases of capture in the ‘evening,’ and one of these cases was when the electric light
was used in the water to attract the surface forms. The young in the adult form [equivalent to fourth
and possibly fifth and sixth stages described in this work] were, however, often taken in the evening
and were almost always attracted by the electric light. In my experience the young of the adult
form were much more frequently taken at the surface than the larve.”

THE AMERICAN LOBSTER. 189

cunners then made their appearance and snapped up the larvie right and left. Two
hours later the lobsters were diffused over the whole surface of the pool, a large num-
ber of them swimming close to the surface. The paler larvie, with chromatophores
contracted, can not be easily distinguished at a distance of a few feet, but when one
of their eyes is turned at the right angle it glows, like a minute electric spark, with a
greenish light. At 1 p.m. the surface on the lee side of the pool swarmed with larvie.
Occasionally one could be seen to attack and drag another down. They swim about
aimlessly with considerable rapidity, now rising or falling, and changing their direction
frequently. The majority had now become quite red. Later in the afternoon nearly
all had disappeared, having been swept out by the tide or destroyed by the cunners
and other fish in the pool.

Beperiment 2.—On July 13, 1894, I placed a number of larve, mostly in the first
stage, in a glass dish, next to the window in the hatchery. The larvee immediately
gathered on the side of the dish nearest the window. ‘Turn the dish slowly through
an angle of 180 degrees, and the lobsters invariably flock toward the source of light.
This may be repeated indefinitely, but always with the same result.

Experiment 3.—A box was made with blackened sides, so that when a glass jar
was set in it vertically, with its upper end exposed, igh could enter only from above.
When larve were placed in this, the stronger always rose toward the source of light
into the illuminated zone. Some, however, apparently the weaker ones, remained below.

Haperiment 4.—A light-proof box was then constructed with sliding lid and end,
so that a long, closed jar could be laid in it horizontally. When the lid was removed,
the larvee swam up to the surface in different parts of the jar. When the diffused or
direct sunlight was admitted only at the end the larve invariably flocked toward the
illuminated end and remained there. If any lagged behind, it was because they were
too weak to swim.

These simple experiments! seem to show conclusively that under ordinary circum-
stances the larvee of the lobster are positively heliotropic. I made no experiments on
the effects of changing the temperature conditions. The temperature of the water
used was the same as that of the water running through the aquaria, or about 1°
higher than the water temperature of the harbor (see table 2).

The second experiment was tried in the summer of 1893 with the reverse result,
the lobsters swimming away from the source of light, showing possibly that under
certain conditions the larve are negatively heliotropic (97, p. 82). This experiment is,
however, the least trustworthy of all, since there are always cross lights in a room and
the conditions are consequently changing. Professor Ryder found that under similar
circumstances the larvee gathered on the side nearest the source of light? (172).

The general conclusion reached, that larve swim up to the surface during the day-
time and stay there, probably sinking at night and rising again with the approach of
light on the following day, is supported by the record of the capture of larve which
IT have already given. The taking of larve at night seems to be the exception; their
capture by day the rule.

1In the course of these experiments I had the advantage of consulting with Professor Loeb, to
whose researches our knowledge of heliotropism in animals is very largely due.

*He also says: “At night, orif light is shut off, the young lobsters go to the bottom of the tanks;
and if seems they may then be most actively engaged in feeding if food is placed within their reach.”

190 BULLETIN OF THE UNITED STATES FISH COMMISSION.
THE MORTALITY OF LARVE&.

The following notes illustrate the difficulty of raising the young of the lobster
in close quarters. Old eggs were always placed in the jars, but even when the water
was agitated so that these were floated, the young invariably preferred to feed on one
another. The death rate, however, is due in part to other causes besides cannibalism.

On July 2d, 1893, 130 larvee in the second stage were placed in a 4-gallon jar and supplied with
running water. On July 3d, 108 were alive; on July 4th, 96; July 5th, 89, 3 of these in the third stage;
on July 6th, 63 were alive, 47 of these having molted for the third time. In the course of four days
48 per cent had succumbed.

On July 1st, 100 second larvee were placed in a hatching jar. On July 2d, 82 were living; July
3d, 73; July 4th, 64, 2 of these having molted to the second stage; and on July 5th, 50 were alive, 24
in the third stage. The third larve, 26 in all, were left in this jar, and on July 6th 24 were alive; on
the following day only 6. z

June 29th, 1893, I placed 12 lobsters in the first larval stage in four flat glass dishes (3 to a dish).
By the 1st of July 10 were alive, 4 in the second stage; on July 5th 7 were living, all in the second
stage, and July 6th 1 second larva only was alive.

July 6th I placed 6 first larvee in two flat dishes (3 to a dish) with lobster eggs for food. Each
lobster was 8 mm. long. On July 7th 2 in one dish were alive, both in second stage and devouring
the remaining larva; no change in the other dish. On the 9th, at 9 a. m., 4 were alive, 3 in the third
stage and 1 in the first.

I placed 4 third larve in a hatching jar on the 7th of July. All were living on the 13th, and on
the 15th 3 were alive, having molted to the fourth stage. The smallest had been attacked by the rest
and its thoracic legs were eaten off. I left 2 fourth larve in the jar, both of which were in the fifth
stage on the 27th of the month.

THE EFFECT OF INCREASED TEMPERATURE ON THE RATE OF DEVELOPMENT
OF THE LARVAE.

The following experiment is interesting in showing how the rate of development
is affected by raising the temperature:

July 1st, 1893, I placed 100 first larvee of the lobster in a hatching jar, with food, and heated the
water by means of a block-tin coil to 74° F. The water in the aquaria at this time registered 66.9°
and that of the harbor 66°.

July 2d, 9 o’clock a. m., 56 were alive. Some were weak and lying on their backs at the bottom,
an easy prey of the strong.

July 3d, 9.30 a. m., 56 alive, not looking healthy, many with air bubbles in branchial cavities,
temperature raised to 78°.

July 4th, 41 alive, 28 in second stage, 13 in third stage.

July 5th, 24 alive; left third larvie, 18 in all, in jar.

July 6th, 7 alive; temperature of water 80°.

July 7th, all living, another in fourth stage; left 6 third larve in jar.

July 8th, all alive, 3 molted to fourth stage. One fourth larva had one blind eye; the eye was
small and pigment deficient. All left in jar.

July 11th, all alive, 4 in fourth stage, 2 in third stage.

July 13th, all alive; no change; temperature 79°; left 3 larvx in fourth stage in jar.

July 15th, 2 alive.

July 17th, both living; temperature 79°.

July 19th, both living; temperature 78°.

July 21st, both living; temperature 75°.

July 30th, one alive; temperature 78°.

August 2d, one alive, in fifth stage (length 13 mm.); temperature 79°,

August 5th, last one dead.

We see that with a rise in temperature of from 7 to 13 degrees the third molt was
passed in about 5 days, which is not far from the average age of these larve reared

THE AMERICAN LOBSTER. 191

under the usual conditions. The fourth stage was reached when the larva was 9 to 11
days old, the average age under normal conditions being about 13 days. The only
fifth larva reared was from 33 to 54 days old, which is nearly twice the age of this
larva living under the usual temperature conditions. If the larvae had been less
crowded in the early part of the experiment, and if the temperature of the water
had been raised very gradually, without fluctuations, it is possible that the results
might have been more favorable than they proved to be under the circumstances.
This would require considerable care and close watching, but the experiment, as
performed, seems to demonstrate the impracticability of making such attempts.

The development of the embryo can be hastened by artificially raising the tem-
perature, but it is not certain that any advantage would attend the practice. Bumpus
suggests (30) that if the young were hatched by artificially raising the temperature
of the water during the cold months of the year, and were then liberated into the
ocean, they would be certain to escape the attacks of many summer enemies. This is
undoubtedly true, but it is almost equally certain that the young lobsters would
encounter new enemies in winter and that indiscriminate destruction, which must be
very great at any time, would then be enhanced.

THE DEVELOPMENT AND MORPHOLOGY OF THE BODY AND APPENDAGES.

It was my original intention to trace in detail the development of the form of the
body and its appendages, but I have not been able to devote as much time as I had
wished to this subject. With this in view, however, I have given a pictorial history
of the development of the most important parts, which will be found chiefly on plates
27-35.

Professor Smith has already described the tegumentary appendages of the first
three larvie and the ‘‘early stages of the adult form,” which, as I have shown, compre-
hend the fourth, fifth, and in some cases the sixth stages. In describing these I shall
avoid repetition as far as possible, and pay most attention to those parts upon which
few or no observations have been made.

THE BODY.

The carapace.-—The carapace arises in the embryo as folds of the ectoderm, the
lateral and posterior parts being the first to appear (cut 34 and fig. 234). In the first
larva it has the form shown in fig. 110, plate 35. It is somewhat gibbous behind, and
is armed in front with three downwardly directed processes, a median, slender, sharp-
pointed rostrum, and two lateral teeth. There is also a keel-like process on the middle
line near the base of the rostrum. The latter is nearly as long as the rest of the
carapace. The position of the future cervical fold or groove is very faintly marked.
In the second and third larval stages the rostrum becomes expanded horizontally into
a thin plate with toothed margins, but increases very little in length (figs. 109, 111,
112).

In the fourth larva (figs. 113, 115, plate 35) the cervical groove is well developed;
the rostrum is a thin, triangular plate, bordered with spines and plumose sete. The
terminal spine is usually bifid at its apex, carinate below, and turned slightly upward.
The length of the rostrum is now but little more than one-third that of the entire cara-
pace. The anterior lateral spines are much reduced. Tendon marks now make their
appearance, but are more pronounced in the fifth and sixth stages (fig. 114). Areas of
absorption, corresponding to the median longitudinal stripe, the “welt” and lateral

192 BULLETIN OF THE UNITED STATES FISH COMMISSION.

bright blue areas of the carapace of the adult lobster are clearly seen. The fine trans-
verse hair line, just above the cervical groove, behind the second antenna, can also be
detected. The cross-shaped figure seen on the upper surface is formed by the wide
median absorption area and the cervical groove with which it is continuous on either
side. Besides the fringing hairs, the whole surface is covered with short sete which
correspond in some measure at least to the hair pores of the adult carapace. In
certain cases some of these changes, as in the relative lengths of the rostrum and
anterior lateral spines, are far less marked. The anterior median carina is not promi-
nent after the third stage.

The carapace of the fifth stage is illustrated in fig. 114. The characteristic tendon
marks, which have been described, are very conspicuous, The rostrum is narrower
and in the sixth stage is about one-fourth the length of the entire carapace.

In a young lobster 35 mm. long, which had molted about twelve times, the shape
and areolation of the carapace were very similar to that of the adult.

The abdominal segments.—In the first larva (plate 20) the abdomen has its full
number of segments. The first is unarmed and partially covered by the carapace.
The second, third, fourth, and fifth somites bear early a prominent median spine, which
projects upward and backward from the posterior end of the tergum. Each of these
segments also bears upon either side a long, sharply pointed pleural spine, which
projects backward.

The median spines, of which the last two are the longest, are gradually reduced
during subsequent stages and finally disappear at the fourth molt. Meantime the
pleural spines become shorter, shift their position slightly, and in the fourth larva

point downward.
The disappearance of the median dorsal spines is, however, not uniform, but

subject to considerable variation, as Shown by the following observations upon eleven
larve in the second and third stages.

TABLE 36.—Variation in time of disappearance of the median tergal spines of the larval abdomen.

a No. of abdominal somite.

Monee | Stage of development. 3 5 F 5
1 | Second larvae secs -c-- -- Boal} 1enGl, 1 1 al

25 See: OY. fe secant yee eee ee Rud. 1 1 1

3 0 1| 1 il

4 0 1 | 1 1

5 0 | 0 | 1 1

6 nl | 1 1

7 Rud. | 1 1 1

8 0 | eet

9 |- 0 1 1 1

10 0 0 1 1

11 Rud. 1 1 1

rud. = spine rudimentary. 1 = spine present. ( = spine absent.

We see by the preceding table that the median spine of the second abdominal
segment may entirely disappear at the second molt or persist in either a rudimentary
or perfect condition even after the third ecdysis, while the spine of the third somite,
though usually present, is sometimes absent in the third stage. (Nos. 5, 10.)

The sixth abdominal somite bears at its posterior margin a pair of dorsal spines
on either side of the middle line. These curve backward over the telson, and are
much smaller than the median spines (fig. 33, plate 20). They disappear at the fourth

molt.

THE AMERICAN LOBSTER. 193

The respiratory organs.—In the adult lobster there are twenty pairs of gills, one
of which, belonging to the second pair of maxillipeds, is rudimentary. There are 6
podobranchix, 10 arthrobranchie, and 4 pleurobranchi, distributed according to the
following table:
TABLE 37.—Branchial formula.

Podo Arthrobranchia. Pl
Te ates meals 6 ne do- parr BEE Bs euro- ot
Thoracic segments and appendages. pranichinse ee Rrnaniene Totals.
VII, first maxilliped -.-............ 0 (ep.). 0 0 0 0 (ep.).
VIII, second maxilliped -........-. 1rud.(ep.). 0 0 0 1 rud. (ep.).
TX, third maxilliped ----........... 1 (ep.). 1 il 0 3 (ep.).
X, first pereiopod.... ---| 1 (ep.). if 1 0 3 (ep.).
XI, second pereiopod -| 1 (ep.). 1 1 L 4 (ep.).
XII, third pereiopod. -| 1 (ep.). 1 1 1 4 (ep.).
XIII, fourth pereiopo cecal! L(G) 1 ul 1 4 (ep.).
XIV, fifth pereiopod. - al] © 0 0 1 1
Totalerecascone ee esce cesses 7 6 (ep.). b) 5 4 20(1 rud.).
ep. = epipodite. rud. rudimentary.

The first larva has no rudiment of a podobranchia in the eighth somite, but all
the other branchi are represented. The podobranchi of the following segments are
very small and are partially exposed, together with their reniform epipodites. In the
second larva the podobranchie are covered by the carapace (plate 21) and the branchial
formula is complete (fig. 101, plate 34).

The gills are developed in the embryo as simple folds or pouches in the body
wall.’ They belong to the trichobranchiate type, the respiratory surface being gradu-
ally increased by growth of the multiserial branchial filaments.

In the fourth larva (fig. 106, plate 34) the podobranchia carries four rows of
filaments, and the mastigobranchia, or epipodite proper, is a long, tapering, hairy
plate.

THE VISUAL ORGANS AND APPENDAGES.

The ocellus.—The median eye, which is present in the first larva, is situated at
the apex of a prominent median papilla, between the paired eyes and antennules. It
is marked by a pear-shaped mass of dark pigment. It disappears in the course of
larval life, and no trace of it can be seen in the adult. The ocellus was observed by
Sars (175) in the first larva of Homarus gammarus.

The paired eyes.—The compound or lateral eyes originate in the embryo as disk-
shaped thickenings of ectoderm, and do not become lobate until a relatively late period
(cuts. 27-34).”. In the summer eggs eye-pigment is developed when the embryo is
about 27 days old. It then appears as a thin line or crescent-shaped area, when seen
from the surface. The eye-spot increases gradually in size, and its characteristic
Shape affords a convenient gauge to measure the embryonic development. (Plate J.)

In the first larva the eye is relatively very large. It is dorso-ventrally compressed
or flattened, as in the embryo and in all subsequent stages. The stalks are propor-
tionally shorter than in the fourth larva, and since they nearly meet in the middle
line in front of the brain, they are practically sessile and immobile.

‘For an account of the development of the Decapod gill see 94, p. 392, figs. 193, 230-233.
°The structure and development of the compound eyes of the lobster have been carefully worked
out by Parker (149),

F.C, B. 1895—13

194

BULLETIN OF THE UNITED STATES

FISH COMMISSION.

in a lobster 58 mm. long (No. 5, table 32) and in an adult male:

The following measurements show the greatest diameter of the eye and the length
of the eye-stalk, as compared with the length of the body, in the first and fourth larvie,

TABLE 38.
First Fourth No. 5, Adult
Measurements. | larva. larva. | table 32.) male.
mn. am. mm. mm,
Greatest diameter of eye......---------- 0. 74 0.8 3 a
Length of eye-stalk..-...........-.----- . 92 1.2 3.8 | 10
en ge thhotwbOd Verne cere ea eee 8 14.5 58 264
Ratio of diameter of eye to total length |
(32 WOO A YS rein GoubdooddnodoudEeeousousens . 092 . 055 . 052 | . 026

The diameter of the eye, expressed in terms of the total length of the body, is
much greater in the first than in the fourth larva, but is relatively twice as great in the
latter stage or in a lobster 2 inches long as in the adult condition. (See p. 163.)

Labrum and metastoma.—Both the upper lip and paired metastoma have in the
first larval stage (fig. 54, plate 28) the general form and appearance which they finally
possess. The surfaces of the latter abound in set. What look like sete occur also
on the labrum, but none are present in the adult organ. (See p. 133.)

First antenna.—The first antenna is a simple appendage up to the time of hatch-
ing. In an embryo about four months old (fig. 107, plate 35, and fig. 27, plate 17)
it is tipped with short sete and shows no trace of segmentation. When the embryo
is five weeks old the first antenna has the appearance shown in figure 77. In the
first larva this appendage is no longer simple, as described and figured by Smith (282),
but the inner, secondary flagellum (plate 27, fig. 40) is present, though a small rudi-
ment, and bears at its apex a single plumose seta. When the stalk is examined from
the under side we can detect traces of segmentation into three parts, but on the upper
surface the proximal cuticular fold only can be seen. The appendage terminates in a
small bunch of set, one of which is conspicuous for its length. Itis possible that in
some cases the flagellum is not liberated until after the second molt, as described by
Professor Smith, but none such were observed. These appendages are immobile in
the first larval stage.

The superficial changes which take place in this appendage during the first five
larval periods are illustrated in plate 27, and will not be described in detail.

In the second larva the segmentation of the stalk into three joints is sharply
defined and the flagella show faint constrictions. The clusters of olfactory sete, which
increase in length and number with every molt, are developed during the first larval
period and appear full-fledged immediately after the second molt.

The auditory pit becomes prominent after the third stage. In the fourth larva
(fig. 43, aw) it is a wide and shallow, -shaped depression, marked with brown pigment
cells, bordered with short sete, and containing a few otoliths or granules of sand. In
the fifth larva (fig. 44) the closure of the auditory sac has already begun. The pit is
filled with otoliths and the irregular orifice is guarded by short, feathery sete. The
constriction of the opening continues until in the adult state it becomes a small pore,
into which it is barely possible to insert the point of a pin.

The first antenna of the European lobster, as represented by Sars (175, tab. I,
fig. 4), agrees essentially with that of Homarus americanus, but the secondary flagellum

THE AMERICAN LOBSTER. 195

is more rudimentary. The antennular nerve was traced by Sars toward the end of
the appendage, where it appeared to divide into two branches.

Second antenna.—The outer antenna of the first larva (fig. 45, plate 27) consists
of three parts, which are represented in the adult (fig. 118)—a two-jointed stalk, a
segmented endopodite, and a scale-like exopodite, terminating in a sharp tooth and
bordered on its inner margin with long plumose hairs.

This is the first of the naupliar appendages to become bilobed (cut 30). In an
embryo four months old, fig. 108 (compare fig. 77), the cuticular molt shows the traces
of only a few terminal sete on either branch.

The progressive changes in the second antenna during the first five larval periods
(figs. 45-49) consist mainly in the reduction of the scale and its feathered sete, in the
rapid growth and segmentation of the slender endopodite, and differentiation of the
latter into stalk and flagellum proper, and in changes in the stalk or protopodite. In
the fourth larva (fig. 48) the first segment (coxa)! of the latter bears a prominent tubercle
(already conspicuous in the third stage), on which the duct of the excretory organ
opens, while the second segment or basis is divided by oblique constrictions into three
parts, as in the adult lobster. The external division bears, next the articulation of
the scale, a stout spine which grows with the gradual reduction of the exopodite until
it finally nearly equals the latter in length. The terminal sete of the flagellum are
rapidly reduced and are barely recognizable in the third larva.

The mandibles.—The jaws of the first larva (fig. 54) consist of a stout basal portion,
with toothed, indurated, coronal surfaces, meeting on the middle line opposite the
mouth, and of a slender, three-jointed palpus, which terminated in the specimen fig-
uredina single strong seta. The cutting edges are asymmetrical, and at the anterior
angle there is a stout, variously toothed process which is separated from the rest of
the coronal surface by a deep groove. As Professor Smith observed, this is most
prominent on the left side.

In the third larva the asymmetry of the coronal surfaces is even more striking,
particularly in the toothed process on the outer side at the anterior end. On the left
side this forms a widely overlapping fold, which carries three sharp teeth. The process
of the right side is smaller, but had also three teeth in the specimen examined.

In the fourth larva the mandible is deeply cleft by a wide groove, as in the adult
(figs. 55-57), and the brush-like palpus folds over the cutting margin into the fossa.

In the fifth stage the mandibles are still asymmetrical, and the teeth are no longer
sharp but tubercular, the smaller being at the posterior angle. The stout-toothed
process of the first larva remains as a blunt tubercle on the left side, where it was
most prominent, but has disappeared from the right side.

First maxilla.—The metamorphosis of this appendage from the larval to the adult
condition is relatively very slight. It consists in the first larva (fig. 51) of coxa, basis,
and a one-jointed endopodite. All are armed at their extremities with set of various
kinds—slender, sensory hairs on the outer segment, a double row of stout masticatory
teeth on the basis, and a cluster of less regular, distinctly serrated, stiff bristles at
the extremity of the coxa.

1'The following abbreviations for the segments of the decapod limb will be used: (1) coxa = cox-
opodite; (2) basis = basipodite; (3) ischium =ischiopodite; (4) meros = meropodite; (5) carpus =carpo-
dite; (6) propodus = propodite; (7) dactyl = dactylopodite.

196 BULLETIN OF THE UNITED STATES FISH COMMISSION.

In the fourth stage (fig. 61) the endopodite is two-jointed, and is tipped with two
nonplumose setie. A few hairs occur at the distal articulation on the inner side and
a larger number at the base on the outer side. The other branches have more of the
configuration and character of the adult state.

In the fifth stage (fig. 62) the terminal segment of the endopodite is folded back
toward the basal joint and bent somewhat as in the adult. The inner margin of the
proximal segment has scattering setw, and those on the outer side near the base now
form a dense bunch, most of which are feathered. The tegumental glands, which later
are so abundant in the foliaceous parts of the maxille, can now be distinctly seen in
at least the basis.

Second maxilla.—The structure of the second maxilla of the first larva is repre
sented by fig. 60, plate 29. It consists of two biramous lobes, the coxa and basis, the
respiratory plate or “bailer” and median endopodite. The masticatory setz are some-
times jointed and but sparsely plumose. The long sensory seta of the endopodite is
also marked by transverse constrictions and has a few lateral hairs, while the fringing
sete of the scaphognathite are all plumose and of nearly equal length. The posterior
lobe is the wider and somewhat spatula-shaped, and this difference is emphasized after
the second molt. Minor changes which occur in the course of the three following molts
concern chiefly the endopodite and the conformation of the mouth parts to the mandi-
bles and of the scaphognathite to the branchial cavity.

First maxillipeds.—In the first larva these appendages have the form shown in fig.
58, and if this is compared with the condition met with in the fourth stage (fig. 59) we
find that the principal changes concern the two-jointed endopodite and the flagelliform
exopodite. In the fourth larva the latter is bordered on both inner and outer margins
with plumose hairs. The set on both protopodite and endopodite are more numerous,
and in the latter branch are much reduced. The respiratory epipodite is relatively a
little larger.

Second maxillipeds—In passing through the first four molts the second pair of
maxillipeds undergo but minor changes (figs. 63, 64, plate 30). The exopodite becomes
segmented, flagelliform, and setigerous. The segments of the endopodite, particularly
their inner margins, become more densely studded with sete, many of which are
serrated. A rudimentary podobranchia is developed. The natural position of the
appendages in the first three larval stages is shown in plates 20-22.

Third maxillipeds.—In the early larval stages (plates 20-22) these appendages are
usually directed forward and bent into nearly a right angle at the third articulation
from the extremity. In the first larva (fig. 69) the distal ends of the three terminal
segments (dactyl, :propodus, meros) are armed with stout setw, some of which are
serrated, while the inner margins only of the proximal divisions are setigerous. The
exopodite reaches beyond the middle of the fifth segment, and is an important swim-
ming organ during the first three larval stages.

The right third maxilliped of the fourth larva is shown in its natural form and
position in fig. 65. The appendage is still partially bent upon itself, as in the first
larva, but the proximal half (first to fourth segments) has been twisted through an
angle of 90°, until what were the inner and outer margins have come to lie in a
vertical plane. The proximal joints are trihedral, and what now forms the inner,
upper margin has developed a row of stout, rather sharp teeth, which are very
prominent in the adult. The podobranchia, which is rudimentary in the first stage,
is now well developed.

THE AMERICAN LOBSTER. 197

The pereiopods.—The general structure of the pereiopods is shown in the various
plates illustrating the larval and adolescent history. For a considerable period before
the time of hatching the great chelipeds can be distinguished by their size. At the
time of hatching all have prominent podobranchiz and long exopodites. After the first
molt the swimming hairs and sete which garnish the endopodites are rapidly evaginated.
The first three pairs of pereiopods are subchelate. After the fourth molt (fig. 67, plate
30) the exopodites are reduced to rudiments and leave no trace in the sixth stage.

The first pereiopods.—In the first larva (fig. 66) the first pair of pereiopods or large
chelipeds are nonprehensile, armed with stout, scattering sete, of which those seen on
the inner margins of the meros and ischium are the representatives of stout spurs
which are developed in the fourth larva. Both propodus and dactyl end in a strong,
nearly straight spine, which in the Jatter joint is conspicuous for its length.

Autotomy of the large chelipeds occurs in the fourth larva, but fusion of the basis
and ischium is not effected until at least after the fifth stage (plate 33, fig. 96, and
plate 30, fig. 67).

In the second, third, and fourth stages the prehensile claw is gradually developed
(plates 20-23). In the third and fourth larve the opposed margins of the large claws
are distinctly toothed, and the latter end in incurved, horny tips.

There is usually but very little or no difference in the size of the large chele until
after the seventh molt. In the sixth stage the extremities are already provided with
numerous tufts of sensory sets (compare plates 23-25). In the later adolescent stages,
when the differentiation of the large claws is complete, these tufts are mostly confined
to the cutting claws, where they form a dense mat over the toothed margins and
extremity of the propodus (plates 10-12).

The differentiation of the chel for crushing and cutting is a gradual process, but
is fairly well established ina young lobster 30 to 40mm. in length (plate 8). It rarely
happens that both claws are similar in the adult stages (see Chapter Ix).

Second and third pereiopods.—The structure of these appendages, which agree,
except in size, is illustrated by fig. 73. In the fourth larva (fig. 74) the chelate struc-
ture is pronounced and the exopodite is a rudiment.

Fourth and fifth pereiopods.—The dactyl of these appendages in the first larva
(fig. 70, plate 31) ends in a very long, nearly straight spine, while the propodus bears
a characteristic cluster of setie close to its articulation with the dactyl.

In later stages (fig. 76, plate 31) the terminal spine becomes reduced and the
' terminal cluster of serrated setz on the propodus is then very conspicuous. In the
fifth larva the constriction at the proximal end of the ischium is clearly defined and
the exopodite has disappeared except as a microscopic rudiment (not shown in fig. 76).

The pleopods.—The second, third, fourth, and fifth pairs of abdominal limbs are
visible as buds beneath the cuticle of the first larva and emerge after the second molt
(plates 20, 21).

The sixth pair of pleopods, which form with the telson the tail-fan, are seen as
rudiments through the cuticula of the second larva and are released with the third
molt.

THE DEVELOPMENT OF THE FIRST PAIR OF PLEOPODS.
No accurate observations have been made upon the development of the first pair

of abdominal limbs, which are specially modified in the two sexes. They are the last
appendages to appear, and their growth and differentiation are very gradual. In the

198 BULLETIN OF THE UNITED STATES FISH COMMISSION.

fifth stage they are represented by small rounded tubercles (fig. 78, plate 32). At this
time there are no external characters by which the sex of the individual can be deter-
mined with certainty.

In the sixth stage (fig. 95, plate 33; lobster No. 111, table 39) this appendage
consisted of a small bud (0.1 mm. long); after the seventh molt (larva 18 mm. long)
its length was doubled (fig. 83).

In lobster No. v1 (table 39) this appendage in the eighth stage (larva 19.75 mm.
long) was a simple bud of about the same dimensions (fig. 80).

In another young lobster, probably a male in the eighth stage (length, 19.3 mm.,
fig. 90), the appendages of the first abdominal somite are similar to those of the seventh
and eighth stages just referred to.

In another case, that of a lobster in sixth stage (No. 01, table 39, fig. 84, plate 32,
length of lobster 16 mm.), this appendage was about equal in size to those just
described. In still another lobster (No. v1, table 39), which was followed from the
fourth stage onward through four molts, this appendage is a little larger and is
partially segmented (fig. 85, plate 32) in the eighth stage. The under surface of the
thorax of this lobster is shown in fig. 89, plate 32, where the openings of the oviducts
are clearly seen, thus determining the sex.

In a young female 35 mm. long (No. x, table 39) this appendage measures 2 mm.
and is composed of two joints (with possibly a small coxal segment) of about equal
length (fig. 86). The distal joint is constricted into a number of smaller segments and
bears a few very minute setz. When the female is 2 inches long the first pair of
abdominal limbs have attained the length of only 3 mm. (fig. 88, plate 32). The
appendage is exceedingly slender and, as in earlier stages, is devoid of pigment. The
peripheral segment is multiarticulate and is fringed with fine, short hairs.

In a male 36.3 mm. long (No. x1, table 39) the appendage, though very minute
(2.3 mm. in length), has the same shape as in the adult. It consists of a two-jointed
protopodite, a minute coxa and long basis, and a grooved distal segment (fig. 87). In
a lobster but little larger (No. xu, table 39), length 40.3 mm., the appendages of the
first abdominal somite are similar, but a trifle longer. As shown in the drawing of
the under side of the thorax of this lobster (fig. 91, plate 32), they nearly meet on the
middle line.

We see that the appendage of the first abdominal ring may assert itself either in
the sixth, seventh, or eighth stages. The buds are developed on the posterior margin
of the sternum of the first abdominal somite, and in the early period of their growth lie
facing each other, transverse to the long axis of the animal (fig. 95, plate 33). ‘These
minute delicate appendages do not at first show any trace of pigment. After seg-
menting into two joints the appendage becomes elevated from the surface of the somite
into a nearly vertical position.

The sex can be determined as early as the eighth stage, but not, as Professor Ryder
supposed, by the appearance of the appendages of the first abdominal ring. At this
stage these vary from 0.20 to 0.27 mm. in length, and may or may not be segmented into
two joints (figs. 80, 85,90). It is only by the openings of the sexual ducts that the sex can
be distinguished at the eighth stage. The under surface of a female in the eighth stage
(21.2 mm. long, No. vu, table 39) is shown in fig. 89, plate 32. The openings of the
oviducts were discernible, and the development of the sterna of the last and penulti-
mate thoracic segments which enter into the formation of the seminal receptacle is
slightly different from the conditions seen in the male.

THE AMERICAN LOBSTER. 199

The sex can not be determined by the abdominal appendages alone until after the tenth
nolt. In two lobsters, 35 and 36.3 mm. long respectively (Nos. x, x1, table 39), which
had probably molted twelve times, we have no difficulty in deciding from the structure
of the abdominal appendages (represented by figs. 86,87) that the first is a female,
the last a male.

The gradual growth of the appendages of the first abdominal somite is illustrated
in table 39. In a lobster 2 inches long (51.8 mm.) these have a length of about an
eighth of an inch (or 3 mm.).

TABLE 39.—Progressive stages in the development of the appendages of the first abdominal somite.

|
| Length of
| 7 | Length a
No. Number in tables. Ne-08 Gh lob: prea; Sex. Remarks.
Sver: appendage.
mm. mm.
I | (86, table 34)...-.-.. 5 14 MQ a Udi |e taterereeretes See fig. 78, plate 32.
IT | (86, table 34)-..---.- 6 16 SCAN Ee eeeseete See fig. 84, plate 32.
TID | (84, table 34).----- 6 16.3 ALO He eeoaenc See fig. 82, plate 32.
V | (84, table 34).-.... 7 18 07} #|l Useenceen See fig. 83, plate 32 (bud without joints).
UAVs ee eons sae cis ce cas 8 19.3 .27 | Male..-..| See fig. 90, plate 32.
VI | (87, table 34).-...- 8 19. 75 .2 | Female -| See fig. 80, plate 32.
VII | (3, table 34).-..--. 8 21.2 .25 | Female -| See figs. 85 and 89, plate 32.
VIII | (38, table 34)....-- 10 26.6 SGN Weseeesac Appendage not segmented.
IX |} (84, table 34)...--- 10 29. 50 32 enaebene Appendage consists of two minute joints.
XX | (17, table 33)..--.- 312 35 2 Female -| See fig. 86, plate 32.
XI | (18, table 33)...-.- 312 36.3 2.30 | Male....| See fig. 87, plate 32.
RoE (dae tablersz)eescec mame 40.3 2.60 |...do ....] See fig. 91, plate 32.
XII | (19, table 33)......}.......- 51.8 3.04 | Female -| See fig. 88, plate 32.
1 Tubercle. 2 Bud. 3 Not accurately determined.

Second, third, fourth, and fifth pleopods.—The condition of these appendages in the
second, third, and fourth larval stages is illustrated by figs. 93,94 and 97, plate 33. Each
appendage consists in the second larva of a stalk with the blade-like endopodite and
exopodite. Rudimentary fringing sete are developed after the third molt, but the
appendage is but little longer and otherwise unchanged. In the fourth larva (fig. 97)
the natatory appendages come immediately into use. The long fringing sete grow
out and the limb itself is almost double its former size.

The telson and * tail-fan.”—The flat telson of the older embryos is deeply cleft
into two lobes (fig. 72), which bear on their free terminal edges short interlocking
sete. The bifurcate condition of the embryonic telson, which recalls very forcibly that
of a protozoea and is probably the remnant of a former larval condition, is retained up
to the time of hatching and is lost only with the molt preceding the first larval stage.

After the first molt the telson appears as a broad, triangular plate (plate 19, and
plate 54, fig. 103) joined immovably to the abdomen and admirably adapted for
swimming. By the aid of this paddle the animal darts rapidly backward with every
flexion of the abdomen. The dorsal surface of the plate is convex, and its posterior
margin is incurved and armed with spines and stout plumose setz, as shown in the
drawing.

The sixth pair of abdominal appendages, which, as already mentioned, are clearly
outlined beneath the cuticle of the second larva (fig. 102,, become broad lamellar pad-
dles in the third stage (fig. 104), and in the fourth larva nearly equal the telson in length
(fig. 105). The outer lamella is jointed at its posterior end and bears on its upper
surface, near the line of the articulation, a short median tooth, as in the adult state.
After the fourth molt the caudal-fan is very similar to that of the adult. The telson is

200 BULLETIN OF THE UNITED STATES FISH COMMISSION.

a quadrangular plate, about two-thirds as broad as long, with an even convex margin
bordered with long fringing sete at its hinderend. The median spine has disappeared
and the long lateral spines are reduced to short, stout teeth.

In the later adolescent stages the fringing sete of the caudal-fan become greatly
elongated until they nearly equal the telson in length. The adult telson is somewhat
spatula-shaped and about as broad as long at its base.

THE METAMORPHOSIS OF HOMARUS GAMMARUS.

Sars studied the first three larval stages of the European lobster in specimens
which he collected at the surface of the ocean. He saw enough to convince him that
they were at this time an easy prey to fish, swimming birds, and to ocean currents
which swept them into unfavorable places (175).

At Espevaer, a fishing-place on the coast of Norway, his attention was directed to

Jarge numbers of lobster larvee, which were there “‘packed together with an enormous |

mass of Calanides (a kind of herring) and other species of pelagic animals, upon which
swarms of herring and birds were feeding.”

The abbreviation of the metamorphosis has been carried a little further in Homarus
gammarus than in the American species. The young of the two forms apparently agree
in color, but are very dissimilar in size. According to Sars, the first three larve of
the European lobster measure 10, 14, and 17 to 18 mm., respectively. If these meas-
urements are representative, the first larva of this species is larger than the second
larva of Homarus americanus, and the third larva larger than the sixth stage. (See
table 25.)

The color of the third larva, according to Sars, is a mixture of yellow-red or brown
and blue-green, and at this stage the integument has lost much of its transparency.

The carapace, the large chelipeds, and abdomen in the first larva of the European
species have reached a stage of development which corresponds very nearly to the
second larval stage of the American form. This is best illustrated by the rostrum,
large chele, and telson. The second somite of the abdomen is devoid of the median
spine, which, as we have seen (table 36), usually disappears in the American form
with the second molt. Sars says that even in the first stage the anlage of the uropods
can be discerned beneath the cuticle. These appendages, however, are not released
until after the third molt, as in our lobster.

THE SHORTENING OF THE METAMORPHOSIS IN THE LOBSTER.

I have discussed in my work on the development of Alpheus (94, p. 380) the
abbreviation of the larval period in Crustacea, and described the remarkable exam-
ples of this phenomenon which the study of the Alphei revealed. We will now consider
the case of the lobster a little more closely than it was possible to do at that time.
What is the cause of the suppression of the zoea stage in the metamorphosis of this
animal?

We can not doubt that this is a secondary phenomenon which has appeared in
comparatively recent times, and that some of the immediate ancestors of the lobster
went through the long metamorphosis after hatching, as the majority of Decapods do
to-day. It is equally certain that something in the environment of these animals has
called forth this change. Why should the lobster be better off with a short metamor-

THE AMERICAN LOBSTER. 201

phosis than the common blue crab (Callinectes hastutus) or common shrimp (Crangon
vulgaris) in both of which the larval life is prolonged? The only clew to an answer lies
in the study of the habits and economy of these animals. The course which the larval
development finally assumes in any species is a compromise between several coutlict-
ing paths. A wide surface distribution is necessary for the continuance of certain
animals, but in order to secure this the larval period must be extended. On the other
hand, a long life at the surface would be death to many species.

Natural selection is operative at all stages of development, and is effective in
increasing the chances of survival mainly in two distinct ways: (1) Hither by increasing
the number of ova or young produced, or (2) by shortening the path of development.
In the latter case the number of eggs is diminished and the size of the egg increased.

The crab and shrimp have adopted the former course and the lobster has followed
the latter. A lobster 104 inches long lays, upon the average, 11,000 eggs, each of
which is about 1.9 mm. in diameter, while Callinectes produces, according to S. I.
Smith (182), 4,500,000 eggs, each having a diameter of only 0.28 mm. Thus the crab,
though much the smaller animal, lays over four hundred times as many eggs. With
the same number of eggs as the lobster and a long larval life, the crab could not
survive. The lobster lives in deeper water than the crab and is probably more sensi-
tive to changes in temperature. The larval period lasts from 5 to 8 weeks; that of
Callinectes probably longer, but.this is not known. Any further shortening of the
development of the lobster would lead to a considerable reduction in the number of
eges, and if the metamorphosis were lost completely so that the animal left the egg in
what now corresponds to its sixth or seventh stage the conditions of life would
be very unfavorable for the young, on account of the sedentary habits of the adults.
The adolescent lobsters (being thus concentrated in a relatively small area) would
fall in vast numbers the prey of fish and crustacea, especially to members of their
own species, before they could establish themselves securely in their retreats along
the rocky shores. (See Chapter Xt).

The advantage of a larval life lies in securing distribution, in this case an absolute
necessity, over wide areas up and down the coast, and at the same time in the immediate
transportation of the young from the shore out of reach of many enemies. This being
true, why, it may be asked, has the larval development been shortened at all? This
has been brought about, in all probability, because of the general slowness which
characterizes the whole period of development and because of the great destruction
which is wrought upon the pelagic larve even under the most favorable conditions.

It is very interesting to notice, as I have already mentioned (p. 200), that abbre-
viation in development is carried a step farther in the European species.

It is a well-known law that a fresh-water life tends to shorten the development of
animals, and this may be due to the fact that the seasonal changes of temperature are
far greater and more abrupt in inland waters than in the ocean.

A life in deep water tends also to shorten development and eliminate the larval
period. Where deep-water forms at the present day have an indirect development, it
is possible that the problem is complicated by other conditions or that the bathic
habit has been acquired in comparatively recent times.

Chapter XII.L—THE EMBRYOLOGY OF THE LOBSTER.

I shall not attempt to give a detailed account of the embryonic history of the
lobster, although for several seasons I have spent much time both in collecting and
preparing material for this purpose. I will offer only a few notes on the early
phases of development, and, to lend continuity to the whole, will sketch briefly the
changes in external form which the embryo undergoes.

Early embryologists, Rathke in particular, to whom reference has already been
made (160), examined the older embryos of the lobster or dissected them from the
egg membranes, but the only paper of this period which attempts to deal directly with
the embryology of the animal is that of Erdl (62), published in 1843. LErdl treats
of the laying of the eggs and the fastening of them to the appendages of the
mother; of the nature of the laid egg and of the external anatomy of the older
embryos; but his work was done before the modern methods of microscopical research
had been discovered. This pioneer observer was thus greatly handicapped and his
results are now of but little value.

Smith figured and described the external anatomy of a well-advanced embryo from
a lobster captured May 2, 1872, at New London, Connecticut (182). This stage nearly
corresponds to that shown in cut 38.

In September, 1891, a paper on the Embryology of the Lobster, by Bumpus,
appeared, in which the early stages, to the close of the egg nauplius period, are care-
fully described and illustrated by very accurate and beautiful drawings (30).

A short account of my earliest studies appeared in 1890 (91), and this was followed
by additional notes in May, 1891 (92), in 1893 (96), 1894 (97), and 1895 (100).

NORMAL DEVELOPMENT.

THE MATURATION AND SEGMENTATION OF THE EGG.

In the section on the growth of the germinal vesicle I have described the only
stage in the maturation of the egg which has been directly observed (p. 154, plate 42, fig.
161), where the germinal vesicle has approached the surface and is undergoing indirect
division, being overtaken in the metakinetic stage. As already stated, it is evident
that in this particular egg the germinal vesicle was about to give off a polar body.

Bumpus, who was the first to detect polar bodies in the egg of the lobster, gives
the following account of them:

They are present in many eggs, and appear to be attached at no special point of the vitellus, so
far as the flattened area is concerned, being sometimes within it and sometimes without. It may be,
however, that I have only seen them in secondary positions; for in some cases they seemed to move
freely about within the egg membrane. They were not observed in process of formation, nor were
they invariably present. Before the blastula is formed they disappear. (30)

I was unable to satisfy myself that the polar cells could be distinguished with
certainty, and so have not figured them. It is difficult to detect such minute bodies
in so large and so opaque an object as the egg of the lobster, and owing to mechanical
causes, possibly through the emission of the polar bodies themselves, minute spherical
globules of food yolk are set free and float in the fluid which underlies the eggshell. A

202

THE AMERICAN LOBSTER. 203

single globule of yolk is practically colorless, and as I have never detected the polar
bodies in stained sections I can not affirm that the small particles which seemed to
answer to their assumed appearance were not detached globules of yolk. In ovarian
eges which had failed to pass out of the body at the time of ovulation I have seen
what looked like polar corpuscles, but here, although the nucleus of the ovum was
at the surface, the observation could not be confirmed by histological analysis. The
position of the nucleus in such cases seems to point to the extrusion of the polar cells
under normal conditions, while the eggs are within the ovary or its ducts.

I have already described and figured the egg of the shrimp, Stenopus hispidus,
in which two cells and a single polar body can be distinguished in sections (95, fig.
1, plate 6). One cell lies at the surface, and very near it in the space beneath the yolk
and shell a spherical mass of deeply staining chromatin, corresponding in size with
the nucleus of the superficial cell. It is probable that the latter represents the ger-
minal vesicle after one division, and that the deeper lying cell is the male pronucleus.
(Compare 94, description of plate, p. 474.)

THE EXTERNAL PHENOMENA OF SEGMENTATION.

A colored sketch of the fresh eggs of the lobster is given in fig. 24, plate 17. These
were laid in an aquarium, and when examined August 11, 1893, were closely adherent
and could be separated only with difficulty. The fresh egg is spherical, oblong, or
somewhat irregular in form, and measures about =; inch in diameter. (See p.55.) It
has in appearance a fine granular texture all over, owing to the uniform distribution
and character of the yolk spherules, and the shell hugs the egg closely in all its parts.

An early sign of development is the flattening of a part of the surface of the
yolk and the consequent elevation of the shell over this area. A liquid, in which a
granular substance is sometimes feebly developed while the egg is still fresh, is
pressed out of the yolk and fills the free space between it and the shell. This flat-
tened area marks the animal pole of the egg and is very characteristic. The surface
of the ovum is often flecked with light syots due to the irregular grouping and per-
haps looser arrangement of the yolk spherules. Light flecks, three to four in number,
but of different character, now appear in the depressed area (fig. 215). These are cells
which are approaching the surface, and their nuclei can now be seen shimmering
through the green yolk.

The phases which immediately follow are represented in figs. 216, 217, and 218,
which were drawn from the same egg at successive stages of development. The ceils
approach nearer to the surface, multiply by indirect division, diffuse about the animal
pole, and bring on the superficial segmentation of the yolk into hillocks as seen in profile
in fig. 218. The drawing shown in fig. 216 was made at 10.30a.m. At the animal pole
there are seen two double rows of cells, 8 in each double row, or 16 in all. These are
arranged in pairs—four pairs of daughter cells in each double row—the products of
recent division. This egg appears in profile in fig. 218. The yolk is now in contact
with the shell over less than half its area, but the yolk hillocks appear about the
animal pole only. At 10.55 a. m., 25 minutes later, 20 cells could be detected. At 12
m., or 65 minutes later, this egg had the appearance shown in fig. 217. The segments
or yolk hillocks were then farther apart. This process continued until the entire
surface of the yolk was segmented.

Opposite sides of the same egg in which that condition was already realized are
represented in figs. 219 and 220. The former shows the animal pole, the latter the

204 BULLETIN OF THE UNITED STATES FISH COMMISSION.

vegetative. Atabout 9.30 p.m., when I began these drawings, the nuclei were in kary-
okinesis; at 10 p.m. nearly all were in the diaster stage (as represented here); at 10.10
p-m. superficial furrows began to appear, separating the daughter cells in the region of
the animal pole. At10.15 p.m. cell cleavage was completed. The cells on the opposite
side of the egg lagged somewhat behind the others, the cleavage furrows in that
region being completed about 5 minutes later. The yolk segments, both before and
after division, were wedged rather closely together and were now polygonal in outline
over the greater part of the egg. At 11 p.m. this egg had the appearance represented
in fig. 221, when seen from the animal pole. The yolk segments or hillocks now
protruded, becoming very convex, and the whole egg took on a beautiful mulberry-like —
appearance, the segments which were visible to the naked eye being dark green with
whitish protoplasmic caps or centers. At 1a. m., or 23 hours after the last cleavage
period was completed, the segments flattened down, and by mutual pressure assumed
a polygonal form, the energy which had been stored up during the interval being now
directed to do the work of the next cleavage.

A similar phase is illustrated by cuts 23, 24, plate G, the former showing the
vegetative pole. When these drawings were made, at 12.55 p. m., the nuclei were
mostly in the diaster stage of division, and in 70 minutes cleavage furrows were
beginning to appear.

An egg in a stage quite similar to that seen in fig. 221 is represented in fig. 222.
When first observed, at 10 a. m., from thirty-six to forty segments were visible over
that half of the egg corresponding to the animal pole. At 10.55 the nuclei were in
active division, At 11.30, when the drawing was completed, cell-cleavage furrows
were beginning to appear, and in 20 minutes the segmentation was completed over
the greater part of the surface. At 12 mn. (30 minutes from the time cell-cleavage
became visible, and 65 minutes from the beginning of karyokinesis) the process was
complete and the segments had begun to swell. The egg in this phase is represented
by fig. 223. At 2.45 p. m. active karyokinesis again began, and at 6.25, or in less
than 4 hours, division of the segments was again completed. ‘This phase of the
segmentation lasted nearly four tines as long as the former period. The drawing of
it (fig. 224) was made at 9 p. m., and represents the side including the vegetative
pole. (See figs. 218, 219, and 220.) ‘The polygonal cells, near the central part of the
area represented, were the last products of this segmentation.

The time occupied in cell division is illustrated by another egg, which was under
observation 74 hours (10.55 a. m. to 6.25 p. m.). It was of about the same age as the
egg shown in fig. 222. At 10.55 a.m. the nuclei were in the diaster or metakinetic
stage of division. At11.40 a. m., or 45 minutes later, cell division or segmentation was
completed. At1 p.m., 80 minutes later, the superficial furrows were very definite and
the protoplasmic cap of each segment was more distinct when examined in reflected
light. At 2.45 p. m., 105 minutes later, or nearly 4 hours from the beginning of the
last period of segmentation, the segments were closely crowded and nuclei were again
in active division. (Stage of the equatorial plate.) At 4.15 p. m., 15 hours later,
cleavage amphiasters were formed, but no furrows. At 6.25 p. m., 2 hours and 10
minutes later, or 3 hours and 40 minutes from the time of appearance of the equatorial
plate, segmentation was completed. Here the total segmentation period lasted about
6 hours and 45 minutes, of which 2 hours and 20 minutes were spent in quiescence
and 4 hours and 25 minutes in activity.

Bull. U.S. F.C. 1895. The American Lobster. (To face page 205.) PLATE F.

mes

Cut 20.—Egg embryo, showing membranes abnormally distended after
prolonged immersion in picro-nitric acid. 29 diameters.
mb', primary egg-membrane, formed in ovary. mb%, secondary egg-
membrane, prolonged into the stalk of attachment, formed by the
cement glands. mb%, cuticular molt of embryo.

Cur 21.—Projection of an egg witb 15 yolk-cells, Cur 22.—Projection of an egg with 28 yolk-cells, 3 in
all near the surface or approaching it. karyokinesis—mostly near the surface.
In these cuts the yolk-cells only are shown. Sections
are represented by dotted lines in cut 22.

Drawn by F. H. Herrick.

THE AMERICAN LOBSTER. 205

About 110 cells are present in the egg shown in fig. 223, and not far from 220 in
the next phase (fig. 224). The lack of uniformity in cell division which was present
in the earlier stages now entirely disappears. In other words, the individual rhythms
of the component cells of the embryo appear to be in harmony.

At the next and following divisions (fig. 225) the protoplasm approaches nearer
and nearer the surface, and the animal and vegetative poles are no longer distin-
guishable. A surface view of an egg intermediate between the stages shown in figs.
224 and 225 is represented in fig. 244, plate 52. The invagination stage soon follows.

INTERNAL CHANGES IN SEGMENTATION.

The histological changes which take place in development up to the beginning of
the invagination stage will now be considered.

The segmentation nucleus in a single egg, from a batch which I obtained on
August 1, was very eccentric in position, and in appearance resembled the germinal
vesicle of the unextruded egg. The nucleus was spherical and lay in a spherical
island of granular protoplasm. The nuclear membrane was very delicate, and could
hardly be demonstrated in sections, while the chromatin had a rather coarse granular
appearance.

The first division takes place near the center of the egg, and the products move
away from each other. In two eggs examined, each of which contained two nuclei
(possibly the pronuclei), one nucleus in each case lay nearer the center and the other
nearer the surface. The nuclei are relatively small, and after a few divisions become
very much smaller. Each is surrounded by a rayed body of protoplasm, in some
cases (as in fig. 249) the rays being exceedingly numerous and delicate, reaching far
out among the yolk-spheres. In an egg which was cut into 56 sections, the first two
cells appeared in the twenty-fourth and thirtieth sections, respectively. In each case
the nucleus was spherical, and the cell protoplasm formed a compact oval island, giving
off no long characteristic pseudopodia, as are seen in fig. 238. In another case, where
the egg was cut into 64 sections, one cell appeared in the thirty-first and its sister
cell in the thirty-ninth section of the series, the latter being in process of division.

In the second and third segmentations which follow, producing four and eight
cells, the products separate and migrate toward the surface. The greater number
tend to move toward the side of the egg corresponding to the animal pole, where the
yolk is first segmented (figs. 215-218, plate 50).

In an egg containing nineteen cells, with yolk undivided, eight were in various
stages of karyokinesis. Some cells were nearer, others farther from the surface, the
majority being about midway between the center and periphery, in different parts of
the egg.

In another egg, where the segmentation of the superficial yolk was completed,
just thirty cells or yolk pyramids were present. (See figs. 219 and 220; a section of
the egg is represented in fig. 242.) The constrictions of the yolk are not simply
superficial, but cleavage planes often reach halfway down to the center of the egg.
The nucleus with its rayed protoplasm lies toward the center of the convex face of
each segment, but is still separated from the surface of the egg by a considerable layer
of yolk. The entire protoplasm is thus distributed among the yolk segments, none of
it remaining in the undivided yolk mass. In surface views the nuclei can be seen
shining threugh the thin stratum of yolk which lies between them and the surface.
Sometimes a segment is partly overgrown by the surrounding cells and squeezed below

206 BULLETIN OF THE UNITED STATES FISH COMMISSION.

the surface, as in fig. 238, but this must not be mistaken for one of the phagocytes or
yolk cells, which are formed in an entirely different manner.

Karyokinetic figures, which are clearly seen in all dividing nuclei, show that up
to this time the plane of cell division is radial, for all cells at least which have
approached as near the surface as those shown in fig. 242. <A little later than this, fig.
224, plate 50, and fig. 244, plate 52, when over 200 cells were present, phagocytes or
yolk cells suddenly appear. One egg showed, when sectioned, the following condition:

Number of cellsvatisurfaces.2. senses asics see eee eee Ae a 219
Number‘of yolkicéllsscs23 -2 de sre eee eee eee 11
Lotal numberof cellstin egg eee aay ee eee eee ee eee renee 230
Number of cells in active karyokinesis:
Radial division ---..- TD Ue est Pirin sct lle et ie le ee Re 17
Tan rental divs] O= sa 02))) eee ane eo ni aetna ere es

The yolk cells are in various stages of migration from the surface to the depths
of the egg. Four have reached points about midway between the surface and center,
and one of these is in the metakinetic stage of division. They originate by the
tangential division of a certain number of the peripheral cells and by the multiplication
of yolk cells thus formed. The peripheral cells at this time are not quite in contact
with the surface of the egg, but are separated from it by a thin layer of yolk spherules.
When a peripheral cell divides in a horizontal or tangential plane, the central daughter
cell migrates into the great yolk mass, filling the egg, while the other remains at the
surface and forms a part of the primitive blastoderm. The process is illustrated in
figs. 236 and 243, the latter showing the formation of a yolk cell near the surface, and
also the division of a yolk cell already formed.

THE INVAGINATION STAGE.

After astage similar to that shown in fig. 225 is reached the peripheral cells continue
to divide in radial planes, and their protoplasm soon bounds the surface of the egg.
Cell division becomes more rapid over one side of the egg, possibly that corresponding
to the animal pole, but this was not finally determined. An area of rapid proliferation
is thus distinctly marked off, and in the midst an invagination of superficial cells
occurs. This begins by the in-wandering of a few cells, which is followed by the multi-
plication of those thus immersed in the common food stock, and by the sinking in of a
small area of the blastoderm about this point. In an ovate egg, like that shown in
fig. 227, the invaginate area lies toward one of the poles.

The depression is at first very shallow, but increases considerably in depth and
becomes a well-defined circular pit. Later it elongates transversely (cut 26), and in
abnormal cases a deep gutter is formed. The character of this depression is indeed
subject to great variation. The pit at the surface lasts from four to five days, when,
after becoming elongated into a slightly triangular slit, by the ingrowth of the sides,
it completely disappears.

In an egg in which there is a distinct patch of cells marking the area of invagina-
tion, but where the depression is very slight or has entirely disappeared, the embry-
onic area which lies in front of the point of invagination is marked by a wonderful
activity among the superficial celis. This is illustrated in fig. 252, plate 54. About
the point of invagination there is a mass of several hundred cells, from which migra-
tion into the yolk has taken place. Many of the cells, both at and below the surface,

Bull. U.S. F.C.1895. The American Lobster. (To face page 206.)

PLATE G

Cur 23.—Egg with about 32 yolk segments present, seen
from vegetative pole. About twenty-eight hours after
fertilization. At 12.05 p.m. the nuclei were dividing,
and at 2.05 p.m. corresponding segmentation furrows
in the yolk had appeared. 29 diameters.

Cur 24.—Reverse side of same egg, showing divided
nuclei at the animal pole. Drawings from living egg.
29 diameters.

Cur 25.—Surface view of embryo 8 days old in invagina- Cur 26.—Surface view of egg in mvagination stage. Pit
tion stage, showing pit at surface, embryonic area, and very distinct, transversely elongated, showing tendency
mass Of in-wandering cells which penetrate deeply into to become horseshoe-shaped. 29 diameters. Embryo
the yolk. These appear now as a dense pear-shaped about 8 days old. August 12, 1892.

cloud when seen through the superficial parts. 29 di-

ameters. From No. 3 (1), table 18, July 9, 1890.

Drawn by I’. H. Herrick.

THE AMERICAN LOBSTER. 207

are in various stages of division, as Shown by the clearly defined karyokinetic figures.
The surface of the egg at the sides, but particularly in front of this area, presents a
striking, and, for a transitory period, a very characteristic appearance. The nuclei
are grouped in pairs, in short strings, or in clusters or nests of a dozen or more. In
many cases these nuclei are breaking down and giving rise to the “ plasma vesicles”
and “chromatin nebule” of Bumpus (30). The degenerating chromatin of these
disrupted cells still reacts vigorously upon the staining fluids, and appears as a
clouded mass of fine particles (fig. 237, Dg.) which in time becomes more diffused and
scattered amid the adjacent yolk granules (fig. 241). The pairs or chains of cells
arise by the usual process of indirect division in radial planes.

The cell nests, as illustrated in fig. 245, plate 52, are the result of a multiple karyo-
kinesis, and are formed immediately by either one or two divisions from a single cell
(yn'). Since the active phase of this process lasts but a brief interval, it is not surprising
that it usually escapes attention. In this egg, nests of nuclei are very abundant at the
sides and immediately behind the region of ingrowth, and occur, as is well shown in
fig. 245, both at the immediate surface (cn) and below it. In most cases a yolk ballis
formed with very definite outlines, its size depending upon the amount of protoplasm
which it contains. The yolk ball is strictly analogous to the superficial yolk-bearing
cell and to the yolk pyramid. The superficial cell, which is a direct descendant of the
enormous yolk segment or pyramid, has this peculiarity in the lobster: By the time
a distinct blastodermic envelope is formed it tends to become distinctly separated
from the rest of theegg. A definite stratum of cells is thus formed consisting of yolk-
laden discoidal or columnar cells. (See figs. 251 and 255, ec.)

The appearance of the cell nest or cluster in a resting condition is shown in figs. 245
and 247. The yolk immediately surrounding it is usually, but not always, segmented
into spherical masses. Upon the side of the egg, opposite the embryo nuclei are far
less numerous and very uniformly distributed. No cell nests or evidence of active
division are seen.

It will probably be found that, whenever clusters or nests of nuclei appear in
the blastoderm or other parts of the embryo of Arthropods, they are the result of
multiple cell division. Some time ago I suggested (94, p. 427) that this would account
for the nuclear clusters which Reichenbach has figured in the large endodermal cells
which form the lining of the mesenteron in Astacus, and which he supposed were due
to a process of direct division (163). Both in this case and in the lobster the division
is attended by the dissolution of some of the chromatin.

The histology of the embryo during the invagination period is illustrated by figs.
246, 251, 254. At a very early stage a few cells break with the surface and migrate a
short way into the egg. A depression about the point of ingrowth soon appears, and
the cells, being bathed with nutriment, multiply rapidly until the condition illustrated in
fig. 251Lis reached. They here form at the surface a definite layer of prismatic elements,
each containing a quantity of yolk with definite boundaries. It should be noticed also
that the nuclei of the in-wandering cells are ofteu inclosed in spherical masses of yolk.

The histological processes which occur at this period vary considerably in different
embryos. Thus in fig. 246 we see a stage of development very similar to that of
fig. 252, but a little earlier. In the former (fig. 246) the cells about the area of
invagination have multiplied until they form a large cluster at the bottom of the pit.
A syncytium is formed, and the protoplasm of the outermost cells lies at the surface,
while the neighboring yolk is thrown into long, tapering segments. Some of these

208 BULLETIN OF THE UNITED STATES FISH COMMISSION.

invaginated cells have wandered a short way only into the egg. Now, if we examine
the peripheral cell envelope, we find abundant evidence of cell division over the side
of the egg where the embryo proper is soon to be built up. Nests of nuclei, often sur-
prisingly large and numerous, are now and then seen in the midst of a spherical mass
of yolk either at the surface or just below it. Isolated cells, though few in number,
also occur, scattered through the peripheral parts of the yolk at this stage. What
is their origin? They can not be referred to invaginate cells, since none of these
have yet wandered to remote parts. Furthermore, these cells tend, not to scatter,
but to migrate in a body. They may be the descendants of the primary yolk cells or
migrants from the peripheral cell envelope, or may originate in both these ways.

At the time of invagination the egg of Alpheus is very similar to that of the lob-
ster in its histological relations. The main difference which is apparent to the eye
is in the larger size or greater amount of food yolk in the latter. I have described
and figured the invagination stage of Alpheus in some detail in my work on the
embryology of this crustacean (94, p. 400, plate xxx1). In this species the primary
yolk cells persist and mingle with the wandering cells derived from the invagination.
An egg of Alpheus saulcyt in the invagination stage contains about 460 cells, of which §
per cent—exactly 37 were found in two separate eggs—are primary yolk cells (94, p.
432, table 1). These yolk cells do not appear to be much more numerous in the larger
egg of the lobster (see cuts 21 and 22, showing eggs with 15 and 28 yolk cells respect-
ively), but in this animal they degenerate faster than in Alpheus, so that at the
invagination period very few are left. On the other hand the occurrence in the lobster at
this time of nests of nuclei within the yolk ball, which lies just below the surface or some
times almost in contact with it, points to migration of cells from the surface after the
invagination stage. In any case most, if not all, such cells degenerate and disappear.

In an older embryo, represented in fig. 254, the pit in the invagination area is
considerably enlarged, and below this a solid wedge-shaped column of cells is seen
advancing straight down into the yolk or bending slightly toward the hinder end of
the embryo. This mass of cells forms what has been called the thoracic-abdominal
plate. It here gives rise in part to a mass of cells which migrate into the yolk and
eventually form mesodermic and endodermie structures. I shall call this cell-mass the
mesendoderm. Regarding these cells we notice in particular the peculiar association of
the cytoplasm with the yolk, the pseudopodia by which they worm their way among
the yolk spherules like so many amcebe, the evidence of cell multiplication and of the
degeneration or breaking down of cells.

Signs of cell degeneration are also present in a striking degree over the embryonic
area of the egg. The surface cells form a single tier of short prismatic elements
loaded with yolk, while beneath them we see a thin cloud of fine chromatin particles.
These are mostly the remains of cells which have migrated thither from the mesendo-
dermic mass, and possibly in part also of cells which have wandered from the surface.

The embryo at a little later period has the appearance shown in plate 53. The
ingrowing plug of cells has a rounded, somewhat pear-shaped outline when seen from
above, the stem end of the pear pointing backward and downward into the yolk.
The embryonic area of the egg presents a beautiful mosaic of cells, among which
karyokinetic figures are abundant. The dividing planes of these cells are always
radial—that is, parallel with a radius drawn from the center to the surface of the
egg, but make any angle with a line drawn upon the surface of the egg, such as that

Bull.U.S F.C. 1895, The American Lobster. (To face page 208 )

on

PLATE H.

Cur 27.—Surface view of embrvo, show-
ing buds of first pair of antennwe and
clouds of in-wandering cells. The lat-
ter extend in great cumulus-like folds
and surround large masses of yolk with
thin layers of cells. Embryo about 9
daysold. August 6, 1891. 29 diameters.

In cuts 25-33 the eggs were fixed with
hot water and Mayer's picro-sulphuric
acid, and stained in Kleinenberg’s hamo-
toxylon or Grenacher’s borax-carmine.

Cur 28.—Surface view of embryo, show-
ing buds of first pair of antennw and
of mandibles. The stomodeum is
present in form of a small transverse
pit, on the level of a line drawn
through the posterior margins of the
antennary buds. The outlines of the
masses of yolk-cells appear much
more circumscribed than in the earlier
stage shown in cut 27. Embryo 9 to
10 days old. August 5, 1891. 29 dia-
meters.

Cur 29.—Surface view of early egg-
nauplius embryo, showing buds of
the first and second antenne and
the mandibles. Mouth or opening
of stomodeum distinct; in-wandering
cells beneath the thoracic abdominal
plate shaded dark. The yolk-cells are
still further circumscribed to outward
appearance, having wandered far into
the egg. Optic disks more clearly de-
fined. Embryo about 10 days old. 29
diameters.

Cur 30.—Surface view of egg nauplius,
slightly older than that shown in cut 29;
second antenne bifid; labrum and tho-
racic abdominal fold present; embryo
about 11 days old. July 12. 29 diame-
ters.

In cuts 25-30 surface-cells are roughly
indicated only in the immediate region
of the embryo.

Drawn by FP. H. Herrick.

Bull. U.S. F.C, 1895, The American Lobster. (To face page 209.)

PLATE |.

Cur 31.—Surface view of egg nauplius,
showing thoracic abdominal fold, The
mouth, as in cut 30, is sereened by the lab
rum, and the optic disks are more sharply
defined; second antennze forked; embryo
about 12 days old. 29 diameters.

Cur 32.—Surface view of egg nauplius,
showing parts much more concentrated
than in earlier stages. Antennz exhibit
traces of segmentation, and the second
antenne have a slender inner branch.
The abdomen is bifid at its extremity,
which nearly touches the labrum; optic
disk lobular; embryo 14 to 16 days old.
August 14. 29 diameters.

Cut 33.—Surface view of embryo with first Cur 34.—Surface view of embryo, showing

maxille budded; embryo 16 to 18 days
old. August 5. 29 diameters.

Tn cuts 31-38 there is little attempt to
show more than the form of the embryo.
The series G to J represents the progres-
sive development of the summer eggs.
Compare the Rate of Development, pp.
55 to 57, and table 18.

5 pairs of post-mandibular appendages.
The antennz have grown obliquely back-
ward until they come to lie nearly paral-
lelwith the abdomen. The telson, which
is now distinctly forked, partially over-
laps the brain. Eye-pigment not yet
apparent. Nearly same stage as 3 (5),
table 18; about 21 days old. From egg
killed in Perenyi fluid, August 15, 1893.
29 diameters.

Drawn by IF. H. Herrick.

THE AMERICAN LOBSTER. 209

through the longitudinal median axis. There is no tendency to form radial strings
or concentric circles of cells with reference to a given center at the surface, such as
Reichenbach (763) has described in the crayfish, a fact already noticed by Bumpus (30).
Diffused clouds or islands of chromatin particles, the wrecks of cell colonies, lie strewn
over the embryonie area, particularly in its forward part. These are for the most part
immediately below the ectoderm. ‘The opposite side of this egg shows nothing par-
ticularly noteworthy and has not been figured. The nuclei are more scattered, cell
division is less frequent, and clouds of chromatin granules are much less extensive.

The internal structure of a little older embryo is illustrated by fig. 255, plate 54.
The most noticeable changes are the great spread of the mesendoderm which, like a
cloud of dense smoke from an engine, rises up and trails backward into the depths of
the yolk with many rounded summits; the columnar form of the ectodermic cells—most
pronounced in the region of the optic disks—and the swarm of degenerating par-
ticles which underlie these regions. Sticking to the basal ends of the prismatic cells,
numerous amceboid elements can also be seen. How do they originate? They must
come either from the mesendoderm or from the ectoderm. That some of them migrate
forward from the region of the thoracic-abdominal plate there can be no doubt, and it
seems almost equally certain that some come from the surface cells. The position of
the nuclei of the peripheral cells frequently points to the theory that some of them are
crowded below the surface by mutual pressure. On the other hand it is sometimes, but
not always, the case that the boundaries of the ectodermie cells are clearly defined.
The ectoderm still consists of a single cell stratum. The ectodermic nucleus is sus-
pended in the middle of the cell, cytoplasm filling the peripheral and deutoplasm
the central ends. Mesendoderm cells also travel backward and sideways from the
thoracic-abdominal plate and settle down upon the ectoderm. The cells which migrate
into the depths of the egg and form the cumulus-like mass have this peculiarity—
they form a connected syncytial mass; their nuclei are small and of irregular shapes.
On the other hand ameceboid cells below the embryonic area frequently possess large
spherical nuclei.

LATER STAGES IN EMBRYONIC DEVELOPMENT.

The development of the external form of the embryo is illustrated by euts 27 to
38 and by plate 51. The mesendoderm cells play an important role at the time the
appendages are budding. In surface views they become less and less conspicuous,
until in the late egg nauplius (cuts 31, 32) they have passed out of sight into the
deeper parts of the egg.

The appendages make their appearance in the following order: (1) First antenne,
(2) mandibles, (3) second antenni, (4) first maxilla, and the remaining thoracic
appendages in regular succession. They are all formed by the folding of the body
wall or ectoderm, and contain solid yolk cores, until these are absorbed and replaced in
part by the mesodermic cells which migrate into them. The second antenna soon
becomes bifid and bilobed at its apex (cuts 30-32), the inner branch representing the
future long flagellum of this appendage. The first antennz remain single until just
before the time of hatching, when the inner branch or flagellum begins to grow out
from the inner lower surface of the primary stalk. The optic disks are flat areas of
rapid cell division.

F.C. B. 1895—14

PAD) BULLETIN OF THE UNITED STATES FISH COMMISSION.

The relative position of the mouth and antenne is illustrated by cuts 28 and 29.
I will add the account given in my paper on the development of Alpheus, where the
lobster was also included, since it applies to the higher crustacea generally:

Before the first antenne are folded, when they are distinguished as dense patches of cells, some
eggs show the primitive mouth as a minute circular pit, lying nearly on a line drawn between the
centers of these proliferating cell areas, but, so far as my observation goes, never distinctly in front of
them. The relative positions of the mouth and first pair of antenne shift very rapidly during the early
period of their growth, before the fully developed egg-nauplius stage. The pit elongates and becomes
a transverse furrow, and by the time the first pair of antenne are clearly marked off as rounded buds,
and before the second pair are raised into folds, the mouth is on a line with the first of these append-
ages. When the second antenne are elevated into folds the mouth is behind the buds of the first pair,
or on a line drawn between their posterior margins (94, p. 442).

At a stage before the appearance of eye pigment, represented in fig. 232, plate 51, a
diffuse but conspicuous patch of ectodermic cells is developed, similar to what I have
already described in Alpheus (94, p. 414). In case the egg is oblong this patch lies
at one pole about 90° behind the embryo.

A stage just previous to the appearance of eye-pigment is seen in fig. 234. The
forked telson now covers the labrum and is reaching up in front of the brain.

The relation between the age and size of the embryo under normal conditions—
the eggs having been laid in summer—may be seen by comparing cuts 23-38 with
table 18. Most of these are from the same batch of eggs.

Eye pigment is developed in about four weeks, and the rate of growt of the
embryo can thenceforward be gauged by the increase of the pigmented area (cuts
35-38).

At a stage before the concentration of the embryo has begun, a little earlier than
that shown in cut 29, Bumpus (30) has described and figured what has the appearance
of arudimentary pair of preoral appendages. These are elongated folds lying parallel
with the convex border of the optic lobe, and separated from it by a slight furrow only.
They are very transitory, disappearing completely after a brief interval. They can
be seen in some of my preparations, but are not shown in the drawings.

HISTORY OF THE YOLK CELLS.

In my paper on the development of Alpheus I have devoted a chapter to the
“Origin and history of wandering cells in Alpheus,” and I have little doubt that what
is said there of Alpheus is generally true of the lobster and of most decapoda.

In Alpheus, as in the lobster, a certain number of cells, 30 to 40, are budded off
from the blastosphere, and form what I have called the primary yolk cells. Wander-
ing cells, or those which enter the yolk and move about in it, have a triple origin,
namely, from the blastoderm, the invaginated cells, and the ventral plate. It should also
be added that both the process of multiplication by indirect cell division and that of
dissolution or degeneration of protoplasm take place simultaneously in the wandering
cells.

During the egg-nauplius period there is a rapid diminution of the wandering ceils, due to cell
disintegration and emigration to those parts of the embryo where mesoblastic organs are being laid
down. The history of the wandering cells in Alpheus is largely the history of the early develop-
ment of the mesoblast and entoblast. The endoderm makes its appearance as a distinct cell layer
during the egg-nauplius period, and takes the form of a narrow sheet of rather large cells, between
the yolk and the rudimentary heart, near the body wall. In the space corresponding to the heart,
blood corpuscles can already be detected, besides scattered mesoblast cells. Both the latter and the
entoblast are derived from the wandering cells which come out of the yolk (94, p. 408).

Bull, U S F.C. 1895. The American Lobster (To face page 210.) Plate J.

Cur 35.—Surface view of embryo with eye-pigment in form Cut 36.—Embryo 6ldaysold. Area of eye-pigment senn
of crescent, as seen from the surface. Telson overlaps circular. Telson behind brain. From No.3 (11), table
brain. Embryo about 26 days old. From series No. 3, 18, September 1. 29 diameters.

table 18, July 26,12m. Cuts 35-38 drawn from eggs
fixed with picro-sulphuric acid. Outline of egg a little
under size. 29 diameters.

| Cur 37.—Embryo 122 days old. Area of eye-pigment « Cur 38.—Embryo 211 days old. Area of eye-pigment
rounded or irregularly ovalin outline. From No, 3 (13) irregular, somewhat oval or rounded in outline. From
table 18, November 1. 29 diameters, No. 3 (16), table 18, February 1. 29 diameters.

Drawn by F. A. Herrick.

THE AMERICAN LOBSTER. 211

In the lobster there appears to be this difference, in that the primary yolk cells
are for the most part, if not wholly, disintegrated before invagination occurs, and
take no part in development. This can not be shown to be the case in Alpheus.

I have spoken of the formation of the primary yolk cells by tangential division, in
Alpheus and other forms, as a process of delamination, on the ground that they repre-
sented a primitive endoderm, and that the egg with primary yolk cells corresponds to
the planula stage of celenterates. I first called attention to this mode of origin of
yolk cells in decapod crustacea in my paper on Alpheus (94, p. 400), and found that
in the lobster they arose by transverse division from the blastospherie cells or from the
peripheral cell layer (since there is no true blastosphere in this egg). The budding of
these cells, moreover, begins before the outwardly migrating cells have reached the
surface and completely surrounded the yolk. The regularity with which this process
occurs “in such typical forms as Alpheus and Homarus argues,” as I remarked in an
earlier paper, ‘‘ for its presence in allied species where it has possibly been overlooked.”
A precisely similar origin and speedy dissolution of yolk cells has been recently
described in Gebia by Butschinsky (37). It seems that there can be no doubt that the
formation of yolk cells at this early period is thelast trace of a process which was once
of importance, but the role which they play now must be an exceedingly minor one. I
have never found more than 28 of these cells in the large egg of the lobster (cut 22),
Here, while it may be admitted that they are phagocytes or yolk digesters, the impres-
sion which they make upon this large mass of material is insignificant, and they are
themselves soon disintegrated and become a part of the general food stock. It is pos-
sible that they are the remains of a primitive hypoblast, that they once played a more
important part as digesters of the yolk than they do at present, and that this function
was usurped by the mesendoderm formed at the time of invagination. The term trans-
verse fission instead of delamination should, however, be used in speaking of this process
(94, see pp. 400 and 419), since no true delamination occurs and nothing certain is
known about the origin and meaning of this process in the decapod crustacea.

DEGENERATION OF CELLS.

I have discussed the subject of cell degeneration in my paper on Alpheus (94, pp.
425-431) and need not refer to the facts again in detail (see figs. 237, 240, 241, plate 52),
The degeneration of cells in the ovary has already been mentioned (p. 152). In the
embryo this breaking down and absorption of cells into the common yolk mass is first
‘seen in the primary yolk cells, and afterwards in the mesendoderm, where it soon
becomes one of the most striking, and at the same time most puzzling, of all the
varied phenomena presented by the developing embryo. Ifwe examine a longitudinal
section of the egg nauplius of the lobster, we find not a few chromatin balls, but a
meteoric swarm of granulated bodies and naked chromatin grains coextensive with
the embryo and reaching a considerable distance into the yolk amid the scattered
mesodermic cells, but perhaps most abundant, as in Alpheus, in the neighborhood of
the stomodzeum. A long, nebulous train of yolk spherules and granules extends
forward a considerable distance in front of the mouth and is especially marked in the
region of the optic disks. The labrum and the folds of the appendages which contain
solid yolk cores abound also in these peculiar granulated bodies. They occur in less
numbers in connection with the mesendoderm cells, which have at this stage traveled
through the greater part of the egg and form a series of irregular sacs filled with yolk.
These yolk masses, with their surrounding sheet or advancing column of cells, corre-

212 BULLETIN OF THE UNITED STATES FISH COMMISSION.

spond to the endoderm sac of the crayfish. In the latter the peculiar cell fragments
also occur.

If one now examines very thin sections under high powers, he finds that the
granules and the granulated bodies correspond in general to the structures found in
Alpheus. The chromatin grains appear sometimes as naked masses in the yolk, and
stain either very intensely or faintly. They are often vesiculated—that is, they appear
as hollow shells (fig. 241). Under favorable conditions it is easy to demonstrate the
fact that these bodies surround particles of yolk, and occasionally they have a cres-
centic Shape, when they seem to be enwrapping a yolk spherule (fig. 240, plate 52)
(94, p. 427). I have shown that the ‘‘secondary mesoderm cells” described in the
crayfish by Reichenbach (163) are undoubtedly products of degeneration which are
afterwards absorbed in the yolk. In this species the endodermie cells which are
loaded with yolk probably divide by multiple karyokinesis, producing nuclear nests or
clusters, some of which in time undergo degeneration. The naked balls of chromatin
which are found in these cells are probably formed in situ, though they unquestion-
ably shift their position in the egg.

Ina species of Cambarus, which I studied at a stage when five pairs of appendages
were present, the endodermal nucleus was surrounded by a thin layer of protoplasm,
which worked its way amid the yolk so as to practicaliy surround a pyramidal mass.
This strongly recalls the serpentine manner in which the cells creep through the yolk
in the egg of the lobster.

Later, when nine pairs of appendages are represented, the endodermal cells have
nearly reached the ectoderm. The yolk within the confines of the ectoderm has an
irregular, pyramidal, or radial cleavage. Centrally it blends with a serum-like fluid,
in which occasional granules or balls of chromatin are suspended. Small spherical
bodies containing a single chromatin ball, or several balls, occur not only in the yolk
underneath the ectoderm and in the vicinity of the endodermal nuclei, but also in the
central yolk of the endoderm sac at various levels below the endodermal nuclei. Thisis
a point of some interest in connection with the fate of these bodies. They wander not
only peripherally but centrally.! Rarely we meet one which is three or four times the
average size, having « small chromatin spherule in its center. These latter become
absorbed and gradually disappear (94, p. 428).

As I have already shown, the plasmic vesicles described by Bumpus (30) in the
ovarian egg are mesodermic cells in the process of degeneration. (For the origin and
history of these bodies see p. 152.)

Later, according to Bumpus, the plasmic vacuoles are represented by chromatin
granules scattered about in the peripheral parts of the yolk.

In the early cleavage stages Bumpus says that the plasma cells are still represented
by chromatin grains, which “are no longer confined to the periphery, however, but
have advanced toward the center and formed an indefinite ring” (30). In the speci-
mens of eggs in the early cleavage stages which I have studied—stained chiefly in
Kleinenberg’s hematoxylon solution—I have never been able to detect any degenera-
tive products whatever. They appear to have been completely absorbed or converted
into yolk before this time.

In a still later period, when the U-shaped embryonic area is differentiated, ‘the
plasma vacuoles,” according to Bumpus, ‘‘are represented by chromatin nebule, which

1The movement of these bodies is probably due wholly to extraneous mechanical causes

THE AMERICAN LOBSTER. 213

generally underlie the triangular and U-shaped areas” and are ‘found as small clouds
between and also outside the limits of the embryonal tract.” He says further that
“chromatin grains, aS was seen in the surface view, are most abundant where ecto-
dermal cells are most numerous.” No inference is drawn from this, but plainly the
true one is not that the larger collection of endoderm cells are centers of cell degener-
ation, but that the mesoblastic cells attach themselves to those parts of the embryonic
ectoblast which are growing the fastest, and by their own dissolution give rise to the
“chromatin nebulie.”

Bumpus does not explain the origin and fate of the chromatin particles which he
accurately figures, but remarks that “structures comparable with the chromatin grains
of the plasma cells are neither mentioned nor figured by Reichenbach, though the
so-called ‘serum’ may represent the region of their activity.” Further on it is said
that ‘‘future comparison may prove these,” the “secondary mesoderm cells,” of Reich-
enbach ‘to be the same as the plasma vacuoles and their chromatin grains;” and
again, “I have been unable to find in Homarus preparations that throw any direct
light on the so-called ‘secondary mesoderm,’”

IT have shown (94) that the ‘secondary mesoderm cells” are not cells at all, but
the products of cell degeneration, and that in their origin and final destiny they bear
the closest resemblance to the “chromatin nebulie” of the lobster.

ABNORMAL DEVELOPMENT.
SEGMENTATION OF THE EGG.

In every batch of segmenting lobster eggs one is sure to meet with many irregu-
lar forms, and in some cases the greater number appear to be abnormal. Nuclei can
be detected at the surface of many of the segments, and if the egg is treated with
Perenyi’s fluid or with an acid the dark-green segments and their nuclei contrast very
strongly with a milk-white coagulable substance in which they seem to be embedded.
Some eggs, which were laid by a lobster on August 23, after a captivity of eight weeks
in a small aquarium, were light-colored, but were normally fixed to the abdomen, and
were fertile, although the segmentation was exceptionally irregular. Sectionsof these
eggs showed an irregular distribution of cells both at the surface and throughout the
yolk. In some places cells appear to have been carried below the surface by over-
growth, and afterwards to have multiplied in the yolk.

Eggs which are otherwise regularly segmented may contain a large superficial
mass of undivided yolk, as in fig. 226, plate 50. Here is a very large mass of yolk about
the pole of the egg—a similar one lay near it on the opposite side—and a considerable
number of smaller segments. When this egg is sectioned it is found that the large
yolk masses are nearly devoid of protoplasm, while the smaller segments contain each
a nucleus which shows traces of degeneration. There is no nuclear membrane, and
the chromatin has assumed a very irregular form.

It is common to find eggs with yolk unsegmented with the exception of one or more
smnall balls at the surface. Sometimes a single large segment is seen, looking as if it
had been pinched off, and in this and in many other cases it is evident that the egg
has in some way received harsh treatment.

In one egg, rather more anomalous than usual, there was a single small spherical
segment at one of the poles of the elongated egg, while the remainder of the yolk was

214 BULLETIN OF THE UNITED STATES FISH COMMISSION.

undivided. A single nucleus was visible in the small segment, but the egg in reality
contained six cells, five lying in the unsegmented yolk.

It would be interesting to know how many of the irregularly segmented cells
eventually attain a normal condition. It seems probable that very many of them do,
judging from the fact that the number of abnormal eggs which later appear when the
nauplius stage is reached is much smaller, yet there is no evidence that any of the
eggs are lost.

THE INVAGINATION AND EGG-NAUPLIUS STAGES.

I will now speak of some interesting variations which occur during the invagina-
tion period and immediately after it.

Instead of the normal ingrowth of cells from the surface into the yolk and the
sinking in of others to form a small circular pit, there is what appears at the surface as
a deep transverse invagination. This issometimes a long crescent-shaped or irregular
transverse fissure, as in the egg of which cut 40 represents a median longitudinal —
section.

In other cases, in which the processes of development have gone further, there is
formed an irregular, oval, or circular disk of cells in connection with the invagination,
as shown in fig. 229, plate 51. Here there is a well-defined rim on one side, while upon
the other the structure seems to blend with the yolk. In a further-developed stage in
the same process I find that the egg has often a well-defined, sometimes round, and
very irregular circumvallate disk of cells. The cells within the vallum are densely
crowded, and the presence of numerous karyokinetic figures shows that at times cell
division may become rapid. Below the surface, both within and without the vallum,
the granular masses of chromatin bear abundant testimony to the degeneration of living
protoplasm which is taking place in the yolk. The columnar aspect of the marginal
cells of the disk can be plainly seen. The way in which this condition is reached is
illustrated by cuts 39 and 40. By the ingrowth (or infolding in consequence of unequal
growth) of some of the superficial or ectoblastic cells into the massive ball of yolk, a
tongue-shaped or island-like patch of cells is formed, on which the embryo proper is
subsequently marked off (figs. 228 to 231).

The egg-nauplius may arise in a depressed central part of the disk, as in fig. 231,
or upon its margins, figs. 228, 230.

We will now glance at the histology of some of the abnormal embryos. Cut 40
shows a median longitudinal section through one of the earlier stages described.
When the egg was examined from the surface a transverse irregular fissure was seen,
corresponding to the pit (Pit) where the sheet of cells dips below the surface. We see
from a study of this egg that a considerable stratum of cells, including the invaginate
area, has grown into the yolk, and that its edges are folded upon themselves. In this
case one side of the disk, corresponding to the anterior end of the embryo, is at the
surface, while the opposite side is deeply embedded in the yolk. Numerous cells have
budded off from this cell plate, particularly at its posterior end, where they multiply
rapidly and move about freely in the yolk, like the normal mesendodermie cells. Like
the latter, they move chiefly in a posterior direction into the deeper parts of the yolk.
Many of these wandering cells are moreover already in process of degeneration. It
looks as if there was a migration of cells from the surface behind the cell plate, but
the appearances may be in this respect deceptive. The yolk flows over the engulfed
cells, but I find in my preparations no new superficial layer of ectoderm established.

THE AMERICAN LOBSTER. 215

Cut 59 represents a median longitudinal section through the embryo shown in
fig. 250, plate51. Here the entire embryo is immersed in the yolk or in a thin coagulable
fluid derived from it, through which it can be seen, while the cell plate touches the
surface in a narrow, bow-shaped area, but dips below again at its peripheral margin.
The cell plate beyond the confines of the thoracic-abdominal process and appendages
of the embryo consists of a single layer of very large cubical or columnar elements
gorged with yolk. In front and behind, the edges of this sheet unite to form a cul-de-
sac, so that the whole structure resembles in form a flattened bag, which is partially
buried in the yolk, with which it communicates by the opening or mouth of the sae
below. The edges of the plate are curled over in the yolk, like one of the limbs of

Cur 39. —Median longitudinal section through ab- Cur 40.—Sagittal section through abnormal em-
normal embryo shown in fig. 230, plate 51. Fixed bryo in early stage of development. Fixed in
with picro-sulphuric acid, stained in Kleinenberg’s picro-sulphuric acid, stained in Kleinenberg’s
hematoxylon, August 9, 1892. hematoxylon, August 9, 1892.

AbP, thoracic-abdominal process. Deg., egenerating cells. ep.f., ingrowing fold of surface-epithelium. Ifo, mouth
ofstomodeum. Pit, pit foriued by ingrowing fold. +7, outward fold of surface epithelium. y.c., scattered cells in yolk.
y., food-yolk, abnormally covering embryo in cut 39.

the letter S. In other respects the histology of this egg-nauplius embryo resembles
that of a normal form, except in perhaps a great preponderance of degenerating cells.
In the embryo, the surface view of which is shown in fig. 228, plate 51, essentially the
Same conditions are seen. These abnormal embryos which have just been described
are due in all probability to a disturbance of the normal mechanical conditions under
which the egg usually develops. It is quite probable that they could be artificially
produced, but no experiments have yet been made in this direction.

I have noticed another interesting abnormal variation in the invagination stage.
(See 91). At a period nearly corresponding to that shown in fig. 255, plate 54, there
is a large irregular cavity or several communicating cavities in the depths of the egg.
This chamber contains very little yolk, and its wall is composed of cells which grasp the

216 BULLETIN OF THE UNITED STATES FISH COMMISSION.

yolk by long pseudopodia. The surface of the wall next the cavity is densely studded
withnuelei. Thisirregular cavity is undoubtedly formed by a folding of the embryonic
area, brought about by unequal growth, like the cases already described, and morpho-
logically lies outside the embryo. This is probably the same as the structure referred
to by Bumpus (30, p. 238). It has nothing to do primarily with either the endoderm
or the alimentary tract.

It seems quite probable that many of the abnormal stages already described may
eventually attain to a normal growth and development, but this is not certain.

DOUBLE MONSTERS IN OVUM AND LARVA.

Brightwell, who gave a description of the young of the European lobster (Homarus
gammarus), in 1835, was the first to notice double monsters in this species. He says:
“Two specimens of the young which appeared double were found, being strongly
united in the head” (24). In 1886 the first particular account of these monstrosities
was given by Ryder (171), who describes four types of fusion among the free-swimming
stages. It is to his kindness that I am indebted for the opportunity of examining the
six abnormal larve which he described, two of which I have figured.

It seemed worth while to trace, if possible, the history of these abnormal larvae
back to their early embryonic stages, but although I examined many eggs from many
individuals, I found only three monstrosities of this kind. The earliest is in the
invagination stage, corresponding to that shown on plate 53. It has the appearance of
a normal egg, except that instead of a single invagination there are two areas of
ingrowth. The axes of these two embryos appeared to be inclined to each other at
an angle of about 135°, and they were separated by considerably more than one-third
the circumference of the egg. The posterior ends of these embryos are the nearest
together, as with the others which I have observed. There is no cellular union of the
embryos in the yolk, but they meet in a common peripheral layer of cells, the nuclei
of which are now widely scattered, except in the immediate embryonic areas.

The next youngest stage obtained was the egg-nauplius, which I have repro-
duced in fig. 235, plate 51. The two embryos are similar in every respect and lie almost
exactly opposite each other. The thoracic-abdominal plate of one embryo is joined to
that of the other by a long train of cells which extends through the yolk just below
the surface. These have the general character of migrating mesendodermie cells,
and some have already passed into the depths of the egg.

In a little older double egg-nauplius the long axes of the two embryos make an
angle of about 160° with each other. Their posterior extremities are apposed and,
as in the first instance, separated by about one-third the circumference of the egg.
It is probable that had the two latter monsters been allowed to develop they would
have appeared, when ready to hatch, as if fused, back to back, like the fourth type
described by Ryder, in which four eyes were developed, two to each embryo, two
distinct sets of mouth parts, and biramous locomotor appendages. As Ryder remarks:
“This relation of two perfectly formed embryos in the same lobster egg is exactly the
reverse of that which is observed in vertebrates” (177).

In the first type of larva described by Ryder there are no eyes; the cephalo-
thoraces are fused completely, both laterally and anteriorly, and the separate abdo-
mens diverge at a wide angle. In his second type (fig. 200) there is a single median
eye on the line of fusion of the cephalo-thoraces. The abdomens diverge at a very
wide angle, and, as seen in the drawing, there is a fusion of the first pair of antenne.

THE AMERICAN LOBSTER. Zi

This shows that parts of the embryo on the middle line, including the ocellus, have
disappeared, and that the large median pigment spot is beyond question the last trace
of the fused compound eyes.

In fig. 199, which illustrates the third type described by Ryder, the cephalo-
thoraces are fused laterally and anteriorly; there is no median eye, but a pair of
compound eyes, the right of which is the right eye of the right embryo and the left
the left eye of the left. The stomachs are fused on the middle line, but there is no
apparent union of the antennz or mouth parts. Behind the stomach the parts are
all double.

It is evident that the causes which have produced the monsters with a single
pair of compound eyes (fig. 199) are of exactly the same nature as those which have
produced the monster with a single median pigment spot. In the latter case their
action has been more prolonged. It is also evident that these abnormal larve have
been derived from embryos like those which I have described. There is, however,
this noticeable distinction: In the abnormal embryos the posterior ends of the bodies
are apposed and united, while in the larvie the anterior ends are united, the posterior
parts being widely divergent. It seems to me probable that the apposition and union
of the tail ends of the embryo do not last long, and never involve anything more than
the cells in the yolk; that two distinct thoracic-abdominal processes and two distinct
tail folds are formed, which begin to diverge at an early period. Along with these
changes a process of fusion apparently takes place between the anterior parts of the
two embryos, which are at first entirely separate and distinct, excepting for the yolk
and peripheral cells (ectoderm) which unite them.

The fusion of parts does not take “place coincidently with the process of gastrula-
tion,” as Ryder suggested, and does not begin to show practical results until after the
egg-nauplius stage. In regard to the way in which the different degrees of fusion
have been brought about, Ryder applies the rule adopted by Rauber for the interpre-
tation of fish embryos—that the degree and manner of fusion is ‘determined by the
width of the angle at which the embryonic axes were primarily inclined to each other.”
This principle probably applies to the double monsters produced from the lobster’s
egg, but the process of fusion seems to me to be something entirely distinct from the
conecrescence seen in the parts of the normal embryo. We have to do here with the
fusion of two embryos which are practically distinet from the first.

NOTE ON THE DEVELOPMENT OF CAMBARUS.

I received through the kindness of Professor J. KH. Reighard, in the fall of 1893, a
large number of crayfish of the species Cambarus immunis. They were taken from a
pond in Ann Arbor, Michigan, on the 16th of November, when ice was just beginning
to form. Many of the females were already ‘in berry,” and most of the eggs were in a
very early stage of development, some, without segmentation of the yolk, having been
recently laid. Several were in the egg-nauplius stage, and the oldest which I ex-
amined corresponded to Stage H of Reichenbach (263), having all the thoracic append-
ages, and the folded abdomen had grown forward so that it nearly touched the labrum.

The eggs carried by each female are relatively very large (1.5 mm. in diameter)
and few in number. They are of a light or sometimes rather dark coffee-brown, and
appear to be insecurely fixed to the swimmerets, being liable to drop off or become
detached, especially when several animals are kept together. The species is hardy

218 BULLETIN OF THE UNITED STATES FISH COMMISSION.

and will thrive in confinement, although, as Professor Reighard remarks, the eggs
do not fare so well.

The early phases of segmentation of the protoplasm and yolk correspond very
closely to what has been described in the lobster. The protoplasm divides, and its
products migrate toward a limited area of the surface of the egg, which becomes the
animal pole. This lies usually, if not always, somewhere between the stalk of attach-
ment and the opposite surface of the egg.

In one egg which I studied three small whitish spots could be seen glistening
through the brown yolk. These, which were some distance apart, marked the first
cells to reach the surface and initiate the segmentation of the yolk. In another egg,
which had 27 cells visible at the surface, the shell was raised or distended over that
hemisphere containing the animal pole. This distention of the membrane is not,
however, so uniformly restricted to this part of the egg as is the case with the lobster,
nor were the large yolk hillocks, so characteristic of the latter, discernible here. The
cells are now visible to the naked eye as white dots.

Other eggs are seen in which 40 or more cells could be detected lying rather near
together and covering nearly half the egg, while the rest of the surface is without
trace of protoplasm.

The process of migration from depths of the yolk and division of those cells which
have reached or nearly reached the surface continues until the whole superficies of the
egg is dotted with cells, 80 or more in number. What corresponds to the animal pole
can now be faintly distinguished where the cells are somewhat thicker or closer
together. No segmentation of the superficial yolk has yet taken place, although the
latter is apparently raised slightly about each cell.

As cell division proceeds, the number of surface cells becomes very greatly
increased until 400 or more are visible. The egg then appears to be very nearly
uniformly segmented at the surface, and in certain phases of “rest” has the usual
beaded appearance. This is a late “yolk-pyramid” stage.

The invagination stage soon follows, and a very distinct round pit appears at the
surface, very much in external appearance like the corresponding phase of the lobster’s
egg, excepting that the invaginate cavity is larger.

An invagination of a different character sometimes occurs which is probably
abnormal. A round, very symmetrical depression is seen in the midst of the cells
corresponding to the animal pole. The depression is shallow, and at its bottom three
or more cells can be seen looking as if they had been pushed below the surface at this
point. The cells bordering this depression are sometimes arranged very uniformly.
A similar pit was seen in the midst of the cells of the animal pole before they had
spread over the entire yolk. In this case it was plainly abnormal.

I have not yet studied all the phases of the external segmentation of Cambarus
by means of sections, but from what has already been seen it is clear that it follows
in all essential details the course of events which have been described in the lobster.

Chapter XIV.—SUMMARY OF OBSERVATIONS.

GENERAL REVIEW OF THE LIFE-HISTORY OF THE LOBSTER.

1 will now give a brief summary of the most important observations which have
been detailed in this work, emphasizing in particular those facts which bear upon the
problem of the artificial propagation of the lobster.

(1) Distribution.—The geographical range of the lobster covers about 20 degrees of
north latitude, from the thirty-fifth to the fifty-second parallel, and includes a strip
of the Atlantic Ocean 1,300 miles long and from 30 to 50 miles wide. Its vertical dis-
tribution varies from 1 to upward of 100 fathoms. The most northern point at which
its capture has been recorded is Henley Harbor, Labrador; the most southern point, the
coast of North Carolina. The fishery was begun on the coast of Massachusetts and
gradually extended northward. Consequently, at present the lobster is most abundant
and attains the greatest size in the northerly part of its range, in eastern Maine, and
in the northern maritime provinces of Canada.

(2) There is great diversity in the character of the environment which explains
in some measure the many variations which occur in the habits of the animal, as in
the time and frequency of molting, in egg-laying, in the hatching of the young, and
in the rate of growth.

(3) The lobster displays a considerable degree of intelligence and possesses organs
to which the various senses of the higher animals have been ascribed. The tactile
sense is diffused over the whole body, and the dead shell is perforated by innumerable
minute pores which are capable of transmitting stimuli to sensitive cells lying in the
delicate skin below. It has the sense of smell and of taste, but it is doubtful if the
so-called auditory organs are really ears.

(4) The sea-bottom is the natural abode of the lobster in the adult state, and it
never leaves it and never forsakes the water unless obliged to do so.

(5) Migrations—No coastwise migrations are known to occur, but large numbers
of lobsters move to and from deep water in fall and spring. This bathie migration
varies in accordance with the character of the coast and nature of the bottom. It is
influenced by the temperature of the ocean, by the abundance of food, and to some
extent by the molting and breeding habits.

(6) Many lobsters remain in the relatively shallow and cold waters of harbors
throughout the winter, but at this season they are found only upon rocky bottoms,
where food is most abundant. One may search for them in other situations, as on a
weedy or muddy bottom, during the winter season in vain.

(7) Influence of temperature.—The optimum temperature of the lobster is about
55° F. When the temperature of the sea marks 50° to 55° in spring (May at Woods
Hole) large numbers of lobsters begin to creep nearer the shores, and when again in
the fall (October at Woods Hole) the temperature is near this point, they have already
begun the outward movement.

(8) In severe winters lobsters are either driven into deeper water or, if living in
harbors, seek protection by burrowing in the mud when this is available. This some-
times happens when a sudden lowering of the temperature arises from any cause, and
always when the animals are confined in pounds. In such cases a prolonged cold spell
may prove fatal (see p. 26). The lobster is practically excluded from the coast of
Labrador east of the Straits of Belle Isle by the Arctic current and lingering ice.

219

220 BULLETIN OF THE UNITED STATES FISH COMMISSION.

(9) The adult lobster is essentially a nocturnal animal, being far more active by
night than in the day. The reverse is true in the larval period, when the habits are
entirely different.

(10) Burrowing habits.—The lobster is a great burrower in the sea-bottom. This
habit is developed to an extraordinary degree in pounds or inclosures, at all seasons,
and is practiced, though less regularly, under other circumstances. (Compare para-
graph 8.) The holes, some of which are 2 to 3 feet long, are solely for protection and
are never used while the animal is molting. In the construction of the holes the large
claws are used, and possibly the tail-fan. The lobster almost always enters its burrow
tail first.

(11) Food.—The adult lobster feeds chiefly upon fish, dead or alive, and upon inver-
tebrates. It also takes a small quantity of vegetable food, such as alg and eelgrass.
Fragments of dead shells, coarse sand, and small gravelstones are also swallowed.
The former yield lime, which is absorbed and finally laid down in the skeleton. Many
small fish which inhabit the bottom fall a prey to the sharp cutting-claw of the lobster,
which it uses with great skill and dispatch. The larger lobsters prey invariably upon
the smaller or weaker ones when they can.

(12) The food is seized, torn, and crushed by the large claws, and then taken up by
the appendages about the mouth (maxillipeds, maxille, and mandibles), by which it
is successively torn and chopped fine, when this is possible. While the animal is
eating, a stream of fine particles is passed into the mouth, thence to the gastric mill
or masticatory stomach. Here the food is ground and the fluid or digestible parts
are strained into the small delicate intestine from which they are absorbed. The
indigestible refuse is regurgitated from the stomach-bag.

(13) Impregnation.—In copulation the female receives the sperm from the male in
packets or spermatophores, which are deposited in an external chamber, the seminal
receptacle. This is a blue, heart-shaped structure, situated on the under side of the
body, between the bases of the fourth pair of legs counting from the large claw-bearing
appendages. It opens to the exterior by a median slit with elastic edges, which can
be easily pressed apart.

(14) The male does not discriminate the sexual condition of the female, which may
be impregnated at any time. Itis, however, probable that copulation takes place most
commonly ia spring. The sperm retains its vitality for a long time, in some cases
for at least several months before it is used.

(15) Egg laying.—Much confusion has existed concerning the time when the eggs
are laid. This has resulted chiefly from the fact that the eggs are carried by the
females for the space of from ten to eleven months before they are hatched. About
80 per cent of the spawning females lay their eggs at a definite season in the summer
months, chiefly 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.

(16) In the western end of Vineyard Sound and the region about Woods Hole the
greater number of eggs are extruded during the latter part of July and the first half
of August. -The summer spawning of each year lasts about six weeks, and fluctuates
from year to year backward and forward through an interval of about a fortnight.

(17) This variation in the time of the production of the eggs is due to the fact that
the ovarian ova require at least two years of growth before they are ready for

THE AMERICAN LOBSTER. pap4 ll

extrusion. Anything which affects the vital condition of the adult female will thus
affect the time of spawning.

(18) The spawning season in the middle and eastern districts of Maine is about two
weeks later than in Vineyard Sound. In 1893, 71 per cent of the eggs which were
examined from the coast of Maine were extruded during the first half of August.

(19) At Woods Hole, Massachusetts, 168 egg-bearing lobsters were captured from
December 1, 1893, to June 30, 1894. Outof this number 44, or 25.6 per cent, bore eggs
which had been laid outside of the summer months, chiefly in the fall. A lobster cap-
tured at Matinicus Island, Maine, February 4, 1893, with the yolk unsegmented, and
therefore in a very early stage, is mentioned in table 13, No. 20. Similar captures
recorded in tables 12 and 13 show that the laying of eggs in fall and winter is not rare.

(20) Lobsters laid eggs in confinement only twice during the six summers which I
spent at Woods Hole, although ripe females were frequently placed in the aquaria.
When kept under these conditions, or even in floating-boxes outside, the eggs are
usually not laid, but are absorbed directly from the ovary.

(21) Law of production of eggs.—The law of the production of eggs may be
expressed arithmetically as follows: The numbers of eggs produced at each reproductive
period vary in a geometrical series, while the lengths of the lobsters producing these eggs
vary in an arithmetical series. A lobster 8 inches long produces about 5,000 eggs.
According to this law, a lobster 10 inches long would produce 10,000, a 12-inch lobster
20,000, a 14-inch lobster 40,000. An examination of table 15, in which the number of
eges borne by over 4,000 lobsters is tabulated, shows that this law holds good up to
the fourth term. Whena lobster attains a length of 14 to 16 inches this high standard
of production ceases to be maintained. <A 17-inch lobster produces about 63,000 eggs.

(22) The largest number of eggs recorded for a single lobster is 97,440. In one
case the lobster was 15 inches long and in another 16 inches. In neither was the
animal able to fold its tail on account of the large number of its eggs. This suggests
that the rudimentary condition of the swimmerets on the first abdominal somite in the
female is necessary for the protection of theeggs. The egg-bearing female goes about
with the tail folded. This would be impossible if these appendages were of the usual
size and carried the usual number of eggs.

(23) The average weight of a 103-inch female lobster with eggs is 12 pounds, the
eggs weighing about 2 ounces. A 15-inch lobster, which weighs upward of 4 pounds,
sometimes carries a burden of a pound of eggs. The number of fresh eggs in a fluid-
ounce is about 6,440, and they weigh about 1 ounce avoirdupois.

(24) Incubation period.—The period of incubation for the summer eggs at Woods
Hole is from 10 to 11 months, in one case lasting 335 days, from July 1, 1890, to June
1, 1891, when the young were just beginning to hatch out.

(25) The general range of the hatching period of summer eggs at Woods Hole is
from May 15 to July 15. The greater number are hatched in June.

(26) The hatching of a single brood lasts in some cases over a week, owing to the
slightly unequal rate of development of individual eggs.

(27) The period of incubation of the summer eggs varies with the temperature of
the water. Im Newfoundland the hatching period is said to be from three to six weeks
later than at Woods Hole (15th or 20th of July to the 20th of August).

(28) The hatching period also varies with the time of egg-laying. Thus the
hatching of young lobsters has been observed in November in Newfoundland and
Woods Hole, and in February at Gloucester, Massachusetts.

222, BULLETIN OF THE UNITED STATES FISH COMMISSION.

(29) Time of sexual maturity.—Female lobsters become sexually mature when from
8 to 12 inches long. The majority of all 104-inch female lobsters are mature. In 100
dissections recorded in table 20, 25 females were found, from 9,2; to 12 inches long,
which had never laid eggs, butin 8 of these the ovaries were nearly ripe. Of the 17
immature, 6 were 103 inches or over in length, and in most cases the ovaries would
not have become mature for two years.

(30) Frequency of spawning.—The lobster does not spawn oftener than once in two
years. The spawning interval is probably a biennial one, one set of eggs (summer
eggs) being laid in July or August (at Woods Hole), and the following set in two years
from that time. One has only to examine the ovary of a lobster (see fig. 138, plate 38)
which has just hatched a brood—that is, one year from the time of the last spawning—to
be convinced that annual spawning is an anatomical impossibility. The conclusion
reached from a study of the growth of the eggs is confirmed by the percentage of
egg-bearing females captured during the fall and winter. I have shown that conclusions
deduced from statistics of this kind are often erroneous, especially when observations
have been made in a single locality. When the results of the catch in the harbor of
Woods Hole and off No Mans Land were averaged it was found that about one-half
of theadult females had external eggs, which accords with the view that the spawning
interval is a biennial one.

(31) Relative abundance of the seves.—The relative number of males and females’
varies considerably in certain localities, as at No Mans Land, May, 1894 (table 22),
especially in places affected by the inshore migrations, where the males seem to take
the lead. In other places the number of the sexes is about equally divided; this would
always be true if our observations were extended over a sufficient period and area.

(32) Molting.—By far the greater number of lobsters molt during the months of
June, July, August, and September, but there is no month in which soft lobsters may
not be caught. The male probably molts oftener than the female, which would accord
with the larger proportion of soft male lobsters captured and with the greater size
attained by the male.

(33) Molting lobsters are more often taken on sandy or weedy than on rocky
bottoms.

(34) In preparation for the molt organic matter is absorbed from the shell, making it
very brittle. Mineral salts are also extracted from certain definite areas of the carapace
and chelipeds, an essential condition for the safe passage of the molt.

(35) In molting, the carapace is raised up behind and the body is drawn out through
the opening thus made between carapace and abdomen. Normally, the shell comes off
entire, and there is no break in any of the membranes except that between the carapace
and the rest of the body. The flesh of the large claws is drawn through the narrow
openings of the joints of the limb by the elasticity of the muscles and previous removal
of blood from the extremity. This difficult process is also aided by the absorption of
lime from certain joints of the old shell.

(36) The lining of the alimentary tract is molted, and the gastroliths which are left
inthe stomach are eventually dissolved. The gastrolith isa specialized part of the lining
of the stomach, It is formed in a gastrolithic sac, which is an organ of excretion. It
agrees in chemical composition with the rest of the shell, excepting in the greater
proportion of calcium salts. The view that the function of the gastroliths is to supply
the molting lobster with an immediate supply of lime for the hardening of its soft shell
must be abandoned. The gastroliths more probably represent a mass of lime which

THE AMERICAN LOBSTER. 220

has been excreted in the course of absorption of mineral salts from certain areas of
the shell. The subsequent assimilation of these bodies thus becomes of secondary
importance. It was found that small lobsters (3 to 45 inches long) filled their stomachs
with fragments of dead shells of mollusks and erustacea, probably for the purpose of
obtaining an immediate and abundant supply of lime for hardening the skeleton.

(37) Hardening of the new shell.—From six to eight weeks are necessary under
ordinary conditions to produce a shell which is as hard as the one cast off, and lobsters
destined for the market are in better condition in from ten to twelve weeks after
molting.

(38) Rate of growth.—From the data at hand we conclude that the rate of growth
varies considerably with the individual and its surroundings. The length of the
young lobster when it hatches from the egg is about 7.84 mm., and the increase in
length at each molt is about 15.3 per cent. The lobster molts from 14 to 17 times
during the first year. A 104-inch lobster has molted from 25 to 26 times, and is about
5 years old.

(3)) Regeneration of parts.—All the appendages are capable of regeneration, the
time required for this process depending upon the time of the accident with respect
to the molting period and on the temperature of the water and the abundance of food.
Defensive mutilation or autotomy is perfectly developed only in the large chelipeds.

(40) Size-—The greatest size attained by lobsters is about 25 pounds. This con-
clusion is reached after the examination of skeletons of large lobsters in museums and
comparing them with the measurements of large lobsters of known weight. Most
accounts of the weights of these animals are unreliable.

(41) The weight does not bear a constant relation to the length, owing to the occa-
sional loss of the appendages. The large chelipeds alone contribute from one-quarter
to one-half the weight of the entire animal, and in giants like the Belfast lobster the
weight of the large chelipeds is more than two-thirds that of the entire body. The
weight is also subject to great variation in consequence of the molt, when a heavy
shell is exchanged for a much lighter one.

(42) The adult male is as a rule heavier than the adult female of the same length,
and this difference increases with age in favor of the male.

(43) The egg-bearing females with eggs removed weigh less than the female lobster
of the same length without external eggs.

(44) Hnemies.—Every predaceous fish which feeds upon the bottom may be an
enemy of the lobster. ‘The cod is one of the most destructive to small lobsters, after
the larval stages are passed.

(45) Tegumental glands.—Besides the hair pores, the shell is perforated by innu-
merable minute pore canals which lead into tegumental glands situated in the soft skin.
Each gland has a capillary duct of its own which opens by a pore canal at the surface
of the shell, and each has one or two peculiar cells which resemble nerve or ganglion
cells. These organs are found widely diffused over the surface of the body. and they
also occur in the walls of the csophagus and intestine. It is probable that those in
the swimmerets of the female secrete the cement by which the eggs are glued to the
body, and that in some parts of the body, as in the labrum, they have a secondary sen-
sory function, and are the organs of taste, but this is uncertain.

(46) Color.—The color variations of the lobster, some of which, like the red, blue,
and cream colored types, are nonadaptive, and this is also true of the remarkable color

224 BULLETIN OF THE UNITED STATES FISH COMMISSION.

variations in the larve and older stages. The normal coloration of the lobster has,
however, a protective significance.

(47) Abnormal variations.—Normally the large claws are differentiated for either
cutting or crushing the food, but a rare variation occurs in which the same type of claw
is developed on both sides of the body. The large crushing-claw may be either upon
the right or left side of the body, but this is a question of heredity, and itis probable
that all the young of a brood have the larger claw developed on the same side.

(48) Repetition of parts._-The large chelipeds of the lobster are especially liable to
secondary outgrowths, which undergo a peculiar fission, giving rise to what appears at
first sight as a double claw. It is usually a double part rather than a double append-
age, although duplicate limbs occasionally occur.

(49) Structure of ovary.— When the ovary is ripe it is of a dark-green color and
can be dimly seen through the membrane between the carapace and “tail.” If the
wall of such an ovary is cut the eggs immediately flow out in a stream. The eggs if
immature invariably adhere together or to the substance of the ovary.

(50) After ovulation the ovary is collapsed, of an opaque white color flecked with
green spots, ripe eggs which were left behind—or yellow spots, the remains of similar
eggs from the last reproductive period. The presence of degenerate eggs thus proves
that the animal has already become sexually mature and has previously laid eggs.
The ovaries of lobsters which have never before produced eggs have a uniform tint—
yellow, pink, gray, or green—and are unmistakable. (For histology of the organs,
see Chapter X.)

(51) Development of ova.—The eggs are developed from mesodermic cells of the
ovarian stoma, and the massive food yolk is derived from three sources: (1) From the
protoplasm of the cells destined to become eggs; (2) from the degeneration of follicle
cells, and (3) from the ovarian glands.

(52) When the lobster hatches, its reproductive organ is a minute cluster of
cells 4; mm. in diameter, and in the case of the female it takes from four to five years
for the organ to reach maturity.

(53) The sperm cells are probably motile in the final stage of their history, but
nothing is known either as to how the spermatophores are conveyed to the seminal
receptacles or how the spermatozoa reach the eggs and fertilize them.

(54) Young.—The lobster hatches from the egg as a pelagic free-swimming larva.
It lives at the surface of the ocean from six to eight weeks, when, after having molted
five or six times, it goes to the bottom and appears in habit and general structure like
avery small adult animal. After reaching the bottom it travels toward the shore and
establishes itself in rock piles in harbors and at the mouths of rivers, where it remains
until driven out by ice. At very low tide they can be found by digging away the
loose stones. The smallest, from 1 to 3 inches long, go down deep among the loose
stones, where they are secure from every enemy. When they reach the length of 34
to 4 inches they become bolder, leave their burrows in the rock piles, and seek the
shelter of stones, beneath which they excavate a shallow hole. Young lobsters are
also found in eelgrass and on sandy bottom in shallow water.

(55) At the time of hatching, the egg membranes burst into two halves and are
drawn off over the head. At about the same time the little lobster sheds its entire
cuticle; the plumose hairs which garnish its appendages are evaginated and, leaving its
mother, it swims up to the surface. The first larva has long rowing exopodites on its
thoracic appendages, and a six-jointed abdomen with spatulate telson. At the second

THE AMERICAN LOBSTER. 225

molt rudimentary abdominal appendages appear on the second to fifth abdominal
somites, inclusive, and the branchial formula is completed.

(56) At the fourth molt it loses the use of its larval swimming organs, but still
remains at the surface, propelling itself forward by its swimmerets and backward by
flexion of the abdomen. It is now from three to four weeks old, is half an inch long,
and has characteristic colors.

(57) After the fifth molt is passed the young lobster still swims at the surface,
though it is possible that some leave it during this stage. When the sixth stage is
reached, age five to six or eight weeks, length about three-fourths of an inch, it remains
at the surface for a time at least, but goes to the bottom to stay before the seventh
molt is passed. At the sixth molt all trace of the larval swimming organs is lost.

(58) The molts follow each other at rather short intervals, and during the first
year of life, supposing the animal to have been hatched in June, the lobster molts
from fourteen to seventeen times and attains a length of from 2 to 3 inches. The
main facts of the subsequent life-history need not be repeated.

(59) The problem of artificial propagation of the lobster will be solved when
means are devised by which the larve after hatching can be reared in large inclosures
until the fifth or sixth stage, when they are able to take care of themselves.

(60) Food of larve.—The food of the larval lobster consists of minute pelagic
organisms of all kinds. They show little discrimination at this time, snapping up any
floating objects not too large for them to manage.

(61) Heliotropism of larve.—In the pelagic stages the young lobsters are positively
heliotropic, rising to the surface in the daytime and staying there, and going down at
night. This habit is not invariable, but the capture of the young by day is the rule,
by night the exception.

(62) Survival of larve.—Great destruction is wrought upon the free-swimming
stages by both animate and inanimate enemies. <A survival of 2 in every 10,000
larvee hatched would maintain the species at an equilibrium, and the destruction of
the young under the present conditions of the fishery is probably even greater than
this implies. (For a discussion of this subject see No. 97 of Bibliography.)

(63) The general scarcity of the young in the hatching season in places known to
abound in lobsters is due (1) to their wide horizontal distribution, and (2) to their
destruction.

(64) The whole course of development and later growth is slow. The slow larval
development secures the necessary transportation from the shores and wide horizontal
distribution, which is absolutely necessary for the life of the species. An abbreviated
metamorphosis such as is found in this animal appears to be a compromise between a
still longer development which the animal would have to go through if the egg
possessed less yolk, and the limitations to protoplasmic activity which are imposed by
the temperature of the North Atlantic Ocean.

For the facts pertaining to the development of the embryo the reader must refer
to Chapter x111, and for details and the discussion of general questions to the body

of the work.
F. C. B. 1895—15

Appendix IL—PREPARATION OF THE EGGS.

The eggs of the lobster may be easily prepared for the study of the external surface
in the following way: The fresh eggs are to be placed in either fresh or salt water, which
is heated to near the boiling point, until the green pigment coloring the yolk is perma-
neutly converted into bright red lipochrome (see p. 137). They should then be trans-
ferred to cold water and shelled under the dissecting microscope. The eggshell when
distended slightly with water may be removed by means of very fine-pointed forceps,
nipping the shell and holding it with one pair of forceps while the shell is ruptured
and the egg carefully released with the other pair.

There are two periods in the course of development when it is difficult to remove
the shell without injury to the embryo. These are at the close of segmentation, when
the blastoderm secretes a fine membrane, which becomes soldered to the shell so that
when the latter is removed the blastoderm itself is torn away; and, secondly, either
during the egg-nauplius stage or shortly after it. In the early egg-nauplius two
membranes can be removed, an outer thick one, the eggshell (composed of the primary
and secondary egg membranes), and an inner cuticle, the secreted product of the
embryo. This last usually sticks to the tips of the antenne, the second pair in par-
ticular, and carries them with it when it is removed. It sometimes happens that the
entire embryo is thus stripped off.

After shelling, the eggs should be placed at once in Mayer’s concentrated picro-
sulphuric acid, and left from two to three hours. They may be then transferred to
70 per cent and finally to 80 per cent alcohol, and the latter should of course be
changed until all trace of the yellow salt is removed.

I have frequently made use of 70 per cent alcohol instead of water in making up
the picro-sulphuric acid solution, and it is usually successful. I used it with excellent
results ten years ago in studying the eggs of Alpheus, but the aqueous solution is
perhaps better on the whole. I have tried a great variety of killing and fixing
reagents, but none are to be compared for reliability with picro-sulphuric acid in the
concentrated form.

The eggs are stained by placing them in a vial of borax-carmine for the space of
two to three minutes or longer, just long enough to stain the surface cells only. The
diffuse stain must then be thoroughly removed by acidulated alcohol until the eggs
have a light-yellow color, the nuclei of surface cells only being stained red. Turpen-
tine is one of the best clearing reagents, none of the essential oils in cominon use—oil
of cloves, origanum, thyme, or bergamot—offering any appreciable advantage over it.

Clearing requires but a few minutes, and while it is in progress the eggs should
be placed in a solid watch glass with turpentine, and examined under a dissecting
microscope. With avery small and thin knife they may be cut into halves in any
desired plane. It is better to roll the egg under the knife edge, and thus cut into the
surface all the way round before pressing the knife through the egg. The eggs cut
like cheese at first, but later become brittle and are very apt to break if left in tur-
pentine for too long a time. It is thus best to place a few at a time in the clearing
fluid, and cut them at once.

226

THE AMERICAN LOBSTER. 227

In the treatment of these eggs I have profited by the experience and advice of
my friend Dr. William Patten, whose method of mounting the ova of Arthropods,' and
orienting them for the microtome, which I have essentially followed, leaves little to be
desired. A cell is made of strips of cardboard of the desired thickness, and the
respective hemispheres of each egg are fixed in place by a small drop of concentrated
Schallibaum’s fixative. The cell may be flooded with turpentine while the process of
fixation is going on, and when drained thick balsam is added and the cover glass is
afterwards applied. In this way the most perfect and beautiful preparations can be
made. ;

Eggs are hardened in the same way, when the object is to cut them into sections.
They may be successfully embedded in either paraffin or celloidin. Bumpus has
described his successful use of the latter reagent, which he heartily recommends.”
This method is undoubtedly the surest although the most laborious to pursue. [have
obtained excellent sections of the early and late stages of development by the paraffin
method, and for the older embryos it is certainly preferable. Turpentine and all the
essential oils soon harden the yolk so that it firmly resists the knife. The eggs should
therefore be allowed to remain in the clearing fluid for the shortest possible time only,
and then thoroughly saturated with paraffin. The method which Patten has given
for orientation can hardly fail to meet with success.

Appendix IL—COMPOSITION OF THE SHELL AND GASTROLITHS OF THE
LOBSTER.

[By ALBERT W. SMITH, Ph. D., Assoctate Professor of Chemistry in the Case School of Applied Science. |

The analyses of the shell of the lobster were made from four distinct individuals,
taken at Woods Hole, Massachusetts (Nos. 1 to 4 in the table below), and were selected
with reference to the molting period. The description of the shells and lobsters from
which they were taken is as follows:

No. 1. Hard-shell female with external eggs, August 3, 1894.

No. 2. A hard-shell female lobster near the point of egg-laying; length, 11 inches; July 16,1894. The
ovarian eggs of this lobster were mostly absorbed. (See p. 48.)

No. 3. From a female near the point of molting; length, 10 inches; August 2, 1894, (The gastroliths
of this ‘‘shedder” are described on p. 89, and their chemical analysis is given in No. 3a of
the following table.)

No. 4. The molted shell of a male 11 inches long. (See No. 2, table 24, and p. 89.)

The gastroliths subjected to analysis have the following history:

No. 0a is taken fresh from the gastrolithic sac of a ‘“‘shedder.” (For drawing of this gastrolith sepa-
rated into its constituent spicules see fig. 165, plate 42.)

No. 3a is from lobster No. 3 of this table, taken fresh from the gastrolithic sac of the animal shortly
before it was ready to molt.

No. 4a is from the lobster which cast off shell No. 4 of this table, taken from the stomach of the animal
when soft and preserved in alcohol. (For drawings of this gastrolith see cut 8, plate C; for
description of lobster No. 2, table 24.)

‘Orienting Small Objects for Sectioning, and “‘ Fixing” them, when Mounted in Celis. (Ameri-
ean Naturalist, vol. 28, pp. 360-362, 1894.)
? American Naturalist, vol, 26, pp. 80-81, 1892.

228 BULLETIN OF THE UNITED STATES FISH COMMISSION.

Table showing composition of the shell and gastroliths of the lobster.

Carapace. Gastroliths.
Composition—air dried.

1. pe i |) 2 Bh 4 0a. 3a 4a.
Wreight in (gvam see ee cremmiseealerinaieieie 11.87 | 21.51 8. 48 9.12 Liu |esesece 3. 96
Calculated as calcium oxide—CaO......---) 22.87 | 23.11 | 24.94 | 30.41 | 45.85} 49.14 | 50.82
Magnesium oxide—Mg0O .---.-.--..-.- 3.18 1.14 1.61 1,30 0. 30 0.40 | 0.48
Aluminum oxide—Al, O3—(Fe,03) - --- 0. 68 2.04 1. 04 1. 36 0. 20 0.04) 0.06
Sodium oxide—Na,.O ..-...-..-...----- 0. 89 1.06) 1.35 1, 67 1.09 1.34] 0.55
Silica—SiOj sseecee es eoeee eee eee 0.14 0.29; 0.08 0. 46 0.10 0.06 | 0.08
Phosphoric anhydride—P,O 5. -...----. 3.53 3. 81 5. 12 4,36 4. 43 4.16 | 5.12
Sulphuric anhydride—SO, .--.-..----- 0. 34 0.31 0.58 0.40 0. 07 0.08 | 0.35
Carbonic dioxide—CO, .--.------.----- 21.20 | 17.05 | 17.70 | 23.00] 37.00] 37.10 | 35.00
Water at 100° C—H,O.......--.:----.-|.-..2 2. UGE Soebo ped scaos end bososasdloonasccs 3. 50
Calculated as calcium carbonate—CaCQ3..| 43.68 | 32.83 | 32.93 | 44.60 | 72.44 78.87 | 78.46
Calcium phosphate—Cagz (P04). ------ 7.70 8.32 | 11.18 9.52 9, 67 9.08 | 11.18
Calcium sulphate—CaSOs.---.-..-.----- 0.58 0. 53 0. 99 0. 68 0.12 0.14] 0.59
Magnesium carbonate—MgCO3.-..--.-- 3. 50 2.39 3. 38 2.73 0. 63 0.84 | 1.01
Sodium carbonate—Na2CQ3 ..-.------- W51 1.80 2551 2.85 1. 87 2.28 | 0.93
Alumina, Al,03—(Fe,03).----.-------- 0. 68 2. O4 1.04 1.36 0. 20 0.04 | 0.06
Silica=SiOQoeheseeeccee see neocons. 0.14 0. 29 0. 08 0. 46 0.10 0.06 | 0.08

Organic matter and water, by differ-
Bi scoocoddoccocccaodocouodoooHcnene 42.21 51. 80 48.09 37. 80 14. 97 8. 69 7. 69

As will be seen by reference to the table the principal part of the mineral structure
in the carapace is made up of carbonate of calcium, with some considerable proportion
of calcium phosphate and of magnesium compounds. The gastroliths differ in being
much more largely mineral, and in consisting almost entirely of carbonate and phos-
phate of calcium. All of the specimens contained iron, its quantity being so small
that it was not thought advisable to make a separation of it from the aluminum. A
minute proportion of potassium also was present in every case, but its quantity was
so small that it was detected with difficulty by the spectroscope in the separated
alkali salts.

No successful determination of the quantity of chitin in the carapace was attained,
and no separation of any of the other organic constituents was attempted. The total
quantity of organic matter and water is reported as the difference between the sum of
the calculated percentages of inorganic salts and 100.

The portion of the shell subjected to analysis was taken in each case from the
carapace, from the part bounded by the cervical groove in front and the branchio-
cardiac groove above.

Appendix II.—BIBLIOGRAPHY.

In the following bibliography the literature of the lobster, especially that relating

to its habits and development, will be found to be fairly complete. All papers possess-
ing scientific or historical interest to which reference is made, though some of them
are of minor importance, have been included.

Since, in my chapter on the embryology of this species, I have not entered into

the comparative development of the crustacea, it has been necessary to refer to but few
general works, and all physiological papers have been omitted when not in the direc-
tion of my studies.

ile

2.

10.

11.
12.
13.
iS
1S:
16.
17

18.

Abbott, C. C. Are the ‘‘chimneys” of burrowing crayfish designed ? Amer. Nat., vol. xvi, pp.
1157-1158. Phila., 1884. ;

Aldrovandi, Ulyssis. A. U. philosophi et medici Bononiensis; de reliquis animalibus exsan-
guibus libri quatuor, post mortem eius editi: Nempe de mollibus, crustaceis, testaceis, et
zoophytis. Deastaco. Cap. I, p. 108. Ist ed., fol. Bononie, 1606.

. Andrews, EH. A. Autotomyin the crab. American Naturalist, vol. 24, pp. 188-142, figs. 1-4 (pl.

vi). Philadelphia, 1890.

. Aristotle. On the parts of animals. Transl. by W. Ogle. London, 1882.
. Atwood, N. HE. Onthehabits and geographical distribution of the common lobster. Proc. Bost.

Soc. Nat. Hist., vol. x, pp. 11-12. Boston, 1866.

. v. Baer, K. HE. Ueber die sogenannte Erneuerung des Magens der Krebse u. die Bedeutung der

Krebssteine. Archiv f. Anat., Physiol., etc. Ed. by Johannes Miiller. Pp. 510-523. Berlin,
1834.

. Baker, H. A letter from Mr. Baker to the president, concerning the stones called crab’s eyes, etc.

Phil. Trans. Roy. Soc. (abridged), vol. x, part U1, pp. 876-879, for year 1750. London, 1756.

. Baster, J. Opuscula subseciva. De astacis, tom. 1, lib. 1, tab. 1. Harlemi, 1762.
. Bate, C. Spence. Notes on Crustacea. Ann. and Mag. of Nat. Hist., 2d ser., vol. vu, pp. 297-300,

1pl. 1849.
Bate, C. Spence. Report of the committee appointed to explore the marine fauna and flora of

the south coast of Devon and Cornwall. No. 2. Rept. Brit. Ass. Ady. Sci., 1867, pp. 275-287,
pls. 1-11. London, 1868.

Bate, C. Spence. Report on the present state of our knowledge of the Crustacea. Part 111.
Rept. Brit. Ass. Adv. Sci., 1877, pp. 36-55. London, 1878.

Bate, C. Spence. Report on the present state of our knowledge of the Crustacea. Rept. Brit.
Ass. Adv. Sci., pp. 193-209, pls. v-vir. London, 1879.

Bate, C. Spence. Report on the present state of our knowledge of the Crustacea. Part v.
Rept. Brit. Ass. Ady. Sci., 1880, pp. 230-242. London, 1880.

Bell, Thomas. A history of the British Stalk-eyed Crustacea. Pp. 1-Lxvi1-+ 1-386. London, 1853.

Belon. Deaquatilibus. 1553.

Bergh, R.S. Beitriige zur Embryologie der Crustaceen. I. Zur Bildungsgeschichte des Keim-
streifens von Mysis. Zool. Jahrb., Bd. v1, pp. 491-528, Taf. 26-29. Jena, 1893.

Berniz, Martinus Bernhardus. Chela astaci marini monstrosa. Miscellanea curiosa medico-
physica Academie nature curiosorum, annus secundus, Observatio C, p. 174 (fig.). 1671.

Lo Bianco, Salvatore. Notizie biologische riguardanti specialmente il periodo di maturita ses-
suale degli animali del golfo di Napoli. Mitth. zool. Stat. zu Neapel, Bd. vu, pp. 385-440.

1888.
229

230 BULLETIN OF THE UNITED STATES FISH COMMISSION.

19. Blanchard, Emile. Métamorphoses, meurs et instincts des insectes. Paris, 1868. The trans-
formations of insects, by Martin P. Duncan (London and New York, 1870) is essentially a
translation of this work.

20. Boeck, Axel. Om det norske Hummerfiske og dets Historie. Tidsskrift for Fiskeri, 3die Aar-
gangs. Kjébenhavyn, 1868-1869. Transl.in Rept. of U.S. Com. of Fish and Fisheries, part 011,
1873-1875, pp. 223-258. Washington, 1876.

21. Bouchard-Chantraux. Crustacés du Boulonnais. 1833.

22. Braun, Max. Ueber die histologischen Vorgiinge bei der Hiutung von Astacus fluviatilis. Arbeit.
ans dem zoologisch-zootomischen Inst. in Wiirzburg, Bd. 0, pp. 121-166, Taf. vui-1x. 1875.

23. Braun, Max. Zur Kenntniss des Vorkommens der Speichel- und Kittdriisen bei den Decapoden.
Arbeit. aus dem zoologisch-zootomischen Inst. in Wiirzburg, Bd. 111, pp. 472-479, Taf. 21.
1876-77.

24. 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 Mag. Nat. Hist., etc., first series, vol. VIII, pp. 482-486. 1835.

25. Brocchi, P. Recherches sur les organes génitaux males des crustacés décapodes. Reprinted
from Ann. des sci. nat., 6° série, pp. 1-132, pls. 13-19. Paris, 1875.

26. Brook, George. Notes on the reproduction of lost parts in the lobster (Homarus vulgaris). Proc.
Roy. Physical Soc., session CXVI, pp. 370-385, pl. xvii (figs. 1-5). 1887.

26}. Brooks, W. K. The habits and metamorphosis of Gonodactylus chiragra. (Being chap. III of
the fourth memoir of vol. V of the Proceedings of the Nat. Acad. of Sciences, entitled “ The
Embryology and Metamorphosis of the Macroura,” by W. K. Brooks and F. H. Herrick.)
Pp. 353-360, with 4 plates. Washington, 1892.

27. Brown, Patrick. The civil and natural history of Jamaica. Fol., copper pls. London, 1789.

28. Buckland, Frank; Walpole, Spencer, et al. Reports on the crab and lobster fisheries of Eng-
land and Wales, of Scotland and Ireland. Pp. 1-xx1I+1-xxvi-+1-1v-+1-80, with appendices,
pls. 1-8. London, 1877.

29. Buckland, Frank. Report 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. Aug. 11, 1875.

30. Bumpus, Hermon Carey. The embryology of the American lobster. Jour. of Morph., vol. v,
pp. 215-262, pls. x1v-x1x. 1891.

31. Butschinsky, P. Zur Entwicklungsgeschichte von Gebia litoralis. Zool. Anz., 17. Jhg., No. 452,
pp. 253-256. July 16, 1894. Translated in Ann. Nat. Hist., (6), vol. xv, pp. 677-678. :

32. Cano, G. Morfologia dell’ apparecchio sessuale femminile, glandole del cemento e fecondazione
nei crostacei decapodi. Mittheil. Zool. Stn. Neapel, Bd. 1x, pp. 503-532, Taf. 17. 1891.

33. Cano, G. Sviluppo dei portunidi. Morfologia dei portunidi e corystoidei. Memoria estratta del
tom. VIII, serie 3*, No. 6, della Societa italiana delle scienze, pp. 1-30, tav. 1-11. Napoli, 1893.

34. Carpenter, William. Report on the microscopic structure of shells. Parti, Rept. Brit. Ass. for
Adv. Sci., 1847, pp. 93-134, pls. 1-xx. London, 1848.

35. Carrington, John T., and Lovett, Edward. Notes and observations on British Stalk-eyed Crus-
tacea. The Zoologist, third series, vol. v1, pp. 9-15 (continued). London, 1882.

36. Cavolini. Memoria sulla generazione dei pesci e dei granchi. Napoli, 1787.

37. Chantran, S. Observations sur l’histoire naturelle des écrevisses. Compt. Rend., t. 69, pp. 43-45.
Paris, 1870.

38. Chantran, S. Nouvelles observations sur le développement des écrevisses. Compt. Rend., t. 73,
pp. 220-221. Paris, 1871.

39. Chantran, S. Sur la fécondation des écrevisses. Compt. Rend., t. 74, pp. 201-202. Paris, 1872.

40. Chantran, S. Expériences sur la régénération des yeux chez les écrevisses. Compt. Rend., t. 76,
pp. 240-241. Paris, 1873.

41. Chantran, S. Observations sur la formation des pierres chez les écrevisses. Compt. Rend., t.
78, pp. 655-657. Paris, 1874.

42. Chantran, S. Sur le mécanisme de la dissolution intra-stomacale des concrétions gastriques des
écrevisses. Compt. Rend., t. 79, pp. 1230-1231. Paris, 1874.

43. Coste. (Report of work of Gerbe.) Faits pour servir 4 l’histoire de la fécondation chez les
crustacés. Compt. Rend., t. 56, p. 432. Paris, 1858.

44. Coste. Etude sur les meurs et sur la génération @’un certain nombre d’animaux marins. Compt.
Rend., t. 47, pp. 45-50. Paris, 1858.

45

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a9:

50.
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53.

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56.

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THE AMERICAN LOBSTER. oll

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shrimps and lobsters. Mag. Zool. and Bot., vol. 1, pp. 170-173. 1857.

Translation of same. Bemerkungen iiber den Hiiutungsprocess der Krebse und Krabben. Archiy
f. Naturgesch. von Wiegmann, Jahrg. 4, Bd. 1, pp. 337-342. 1838.

Couch, Jonathan. On the process of exuviation and growth in crabs and lobsters, and other
British species of stalk-eyed crustacean animals. Eleventh Ann. Report Royal Cornwall
Polytechnic Society, 1843, pp. 1-15. London, 1848.

Couch, Jonathan. A particular description of some circumstances hitherto little known con-
nected with the process of exuviation in the common edible crab. (With plates.) Ann. Report
Royal Cornwall Polytechnic Society, 1858, pp. 39-45, pls. 1-3. London, 1858.

Couch, R. Q. On the metamorphosis of the Decapod Crustaceans. Eleventh Annual Report of
the Royal Cornwall Polytechnic Society, 1843, pp. 28-48, pl. 1. London, 1843.

Coues, Elliott. Notes on the natural history of Fort Macon, North Carolina, and vicinity. (No. 2.)
Proc. Acad. Nat. Sci. Phila., 1871, pp. 120-148. Philadelphia, 1871.

Dalyell, John Graham. The powers of the Creator displayed in the Creation. London, 1827.

De Kay, James BE. Zoology of New York, or the New York fauna. Part v1, Crustacea, pp.
23-25, pl. XII, figs.52,53. Albany, 1844.

Desmarest, Anselme G. Considérations générales sur la classe des crustacés. 1825.

Dulk. Chemische Untersuchungen eines Mageninhalts von Krebsen, die sich eben gehaiitet
haben. Archiv f. Anat., Physiol., etc., J. Miiller, Jalrg. 1834, pp. 523-527. Berlin, 1834.

Dulk. Chemische Untersuchungen der Krebssteine. Archiv fiir Anat., Physiol., etc., ed. by
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Du Tertre, Jean Baptiste. Histoire Générale des Antilles habituées par les Frangois. T.
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Histoire Générale des Isles des 8. Christophe, de la Guadeloupe, de la Martinique, et autres
dans Amérique.

Duvar, J. H. Report on lobster fishery of Prince Edward Island, in annual report of the depart-
ment of fisheries, Dominion of Canada. App. No.6, p. 240. 1884.

Duvernoy. Deuxieme fragment sur les organes de génération de divers animaux. Des organes
extérieurs de fécondation dans les crustacés décapodes. Compt. Rend., t. 31, pp. 342-348.
Paris, 1850.

Edwards, H. Milne. Histoire naturelle des crustacés. Vols. 1-3, with atlas. Paris, 1834-1840.

Edwards, H. Milne. Observations sur la structure et les fonctions de quelques zoophytes
mollusques et crustacés des cétes de la France. Ann. des Sci. Nat., 2° série, t. 18, pp.
321-350, pls. 10-15. 1842.

Edwards, H. Milne. Legons sur la physiologie et Vanatomie comparée de ’homme et des
animaux. T.1x. Paris, 1870.

Ehrenbaum, Ernst. Der Helgolander Hummer, ein Gegenstand deutscher Fischerei. Wis-
seusch. Meeresuntersuch., herausg. yon der Kommission zur Untersuch. der deutschen Meere
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Erdl, M.P. Entwicklung des Hummereies von den ersten Veriinderungen im Dotter an bis zur
Reife des Embryo. s.1-x-+ 11-40, Taf. I-1v. Miinchen, 1843.

Fabricius, Otho. Fauna Greenlandica, etc. Pp. 1-xvi+ 1-452, 1 pl. Hafnize et Lipsizw. 1780.

Fabricius, J. Ch. Entomologia systematica, Tom. 11. 1792-94.

Fabricius, J. Ch. Supplementum entomologi systematice. 1798.

Faxon, Walter. On some crustacean deformities. Bull. of the Mus. Comp. Zool. at Harvard
College, vol. vit, No. 13, pp. 257-274; pl. 1, figs. 1-17; pl. 1, figs. 1-9. Cambridge, Mass., 1881.

Faxon, Walter. Selections from embryological monographs, compiled by Alexander Agassiz
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Faxon, Walter. A revisionof the Astacide. PartI. The genera Cambarusand Astacus. Mem.
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Fredericq, Léon. Nouvelles recherches sur l’autotomie chez le crabe. Archives de biologie,
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Gissler, C.F. Description of a hermaphroditic Phyllopod Crustacean (Eubranchipus). Ameri-
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Heller, Camil. Die Crustaceen des siidlichen Europa. Crustacea Podophthalmia, pp. 1-336-+-1-Vv1.
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Herbst, J. F. W. Versuch einer Naturgeschichte der Krabben u. Krebse, nebst einer systemati-
schen Beschreibung ihrer verschiedenen Arten. Bde. 1-111. Berlin u. Stralsund, 1790-1804.

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Bull. Scientif. de la France, ete., t. xx, 1890.

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opment of the compound eye. Johns Hopkins University Circulars, vol. rx, No. 54, pp. 42-44.
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Herrick, Francis H. The development of the American lobster, Homarus americanus. Johns
Hopkins Univer. Cire., vol. 1x, No. 80, pp. 67-68. Baltimore, 1890. See also Zool. Anz. for
1891, pp. 183-137, and pp. 145-149, figs. 1-6.

Herrick, Francis H. Notes on the habits and larval stages of the American lobster. Johns
Hopkins Univ. Circe., vol. x, No. 88, pp. 97-98, May, 1891. Baltimore.

Herrick, Francis H. The reproductive organs and early stages of development of the American
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Embryology and Metamorphosis of the Macroura,” by W. K. Brooks and F, H. Herrick.)
Pp. 370-463-++, with 38 pls. Washington, 1892.

Herrick, Francis H. The life history of Stenopus. Chap. 1 of the above memoir.

Herrick, Francis H. Cement glands and origin of egg-membranes in the lobster. Johns Hop-
kins University Cire., vol. x11, No. 106, p. 103. Baltimore, 1893.

Herrick, Francis H. The habits and development of the lobster and their bearing upon its
artificial propagation. Paper presented at the World’s Fisheries Congress, Chicago, 1893.
Art. 12, Bull. U.S. Fish Commission for 1893, pp. 75-86. Washington, 1894.

Herrick, Francis H. The reproduction of the lobster. Zool. Anz., No. 454, Aug. 13. 1894, pp.
289-292. Leipzig, 1894. Also in the Zoologist, vol. 18, pp. 413-417. London, 1894.

Herrick, Francis H. The Lobster. Johnson’s Universal Cyclopedia, vol. Vv, pp. 317-318. New
York, 1894.

Herrick, FrancisH. Notes on the biology of the lobster. Science, n.s., vol. 1, No. 10, March 8,

pp. 263-266. See also Science, n.s., vol. 1, No. 14, p.382. New York, 1895.

Herrick, Francis H. The Reproduction of the Lobster. Zool. Anz., No. 477, pp. 226-228, June
10,1895. (Review of paper by 8. Garman, No. 73 of this bibliography.)

Huxley, T.H. On the classification and distribution of the crayfishes. Proce. Zool. Soc. London,
pp. 752-788. London, 1878.

Huxley, T. H. An introduction to the study of zoology, illustrated by the crayfish. Inter. Sci.
Ser., pp. I-Xtv, 1-362. New York, 1880.

Hyatt, Alpheus. Moulting of the lobster, Homarus americanus. Proc. Bost. Soc. Nat. Hist., vol.
XXI, pp. 83-90, 1880-1882. Boston, 1883.

Irvine and Woodhead. Secretion of carbonate of lime by animals. Parti. Proc. Roy. Soc.
Edinb., vol. for 1888-1889, pp. 324-354.

Jones, Th.Rymer. On the moulting process in the crayfish. Ann. of Nat. Hist. or Mag. of Zool.,
Bot., and Geol., vol. Iv, pp. 141-143. 1840. Abs. from General outlines of the animal kingdom,
part vu, Sept., 1839. i

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THE AMERICAN LOBSTER. Zo

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198. Ward, Henry B. On the parasites of the lake fish. Trans. Am. Mic. Soc., vol. xv, pp. 173-182.
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203. White, Adam. A popular history of British Crustacea. See Astacus,p. 101. London, 1857.

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207. Wood, W.M. Transplanting lobsters to the Chesapeake—Experiments upon the temperature
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208. Zittel, Karl A. Handbuch der Palzontologie. 1 Abth. 1 Bd. Mollusca u. Arthropoda.
Miinchen u. Leipzig, 1881-1885.

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and fisheries. Appendix No.1, report of J. H. Duvar, inspector of fisheries for the Province of
Prince Edward Island, for 1880. Lobsters, p.231. Ottawa, 1881.

210. 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.

211. Annual report of the department of fisheries, Dominion of Canada, for 1888. Ottawa, 1889.

212. The cultivation of lobsters. Practical Magazine, vol. 2, pp. 258-259. London, 1873.

213. Review of the reports by Buckland and Spencer on the lobster, crab, and oyster fisheries of Great
Britain, Quarterly Review, vol. 144, art, v1, pp. 249-262, 1877.

Appendix IV.—DESCRIPTION OF PLATES.

IP TATE els

Fig.1. The Belfast lobster. Dorsal view of male lobster, captured at Belfast, Maine, May 6, 1891.
Living weight a little over 23 pounds. From photograph of skeleton. Original in pos-
session of the author. For detailed measurements see table 30,No.1. <A little less than
one-fourth natural size.

PLATE 2.

Fig. 2. Ventral view of large lobster shown in plate 1.

Fig. 3. Ventral view of small lobster for comparison with fig.2. Egg-bearing female; length 9finches;
weight about 1} pounds. Most of the eggs which were attached to the abdomen have
been removed.

Both figures reproduced from photograph. About one-fourth natural size.

PLATE 3.

Fig. 4. Profile view of living red lobster. Female, length 113 inches; weight about 2 pounds. Cap-
tured near Mount Desert, Maine. From photograph from life, April 10, 1894. For colored
drawing of this lobster see plate 16, fig. 21. A little over one-half natural size.

PLATE 4.

Fig.5. Adult male lobster, dorsal view. Length 12;; inches; weight 2 pounds 14 ounces. From
photograph from life, December 8, 1893. A little under one-half natural size. Membrane
between thorax and abdomen unnaturally distended.

This lobster, with those represented by the three following plates, figs. 5-8, was captured at Woods
Hole, Massachusetts, December, 1893, and sent alive to Cleveland, Ohio.

PLATE 5.

Fig.6. Adult male. Ventral view of lobster shown in plate 4. From photograph from life. A little
under one-half natural size.

PLATE 6.

Fig.7. Adult female lobster with external eggs, dorsal view. Length 11,8; inches; weight 1 pound 13
ounces. From photograph from life. A little over one-half natural size.

PLATE 7.

Fig.8. Adult female. Ventral view of lobster shown in plate 6. The dark-green eggs attached to the
swimmerets under the tail are very clearly seen. A colored sketch of one of these eggs,
showing the contained embryo, and a cluster of eggs from the swimmerets are represented
by figs. 25, 26, plate 17. One-half natural size.

A lobster of this size produces on the average about 19,000 eggs. The seminal receptacle is seen
between the bases of the third and fourth pairs of walking legs. Compare this with the
organ as it appears in the immature lobster shown in plate 11,
238

THE AMERICAN LOBSTER. 239

PLATE 8.

Fig. 9. Immature female lobster, dorsal view; length 44 mm. (1.73 inches). From photograph, life-e
size. Casco Bay, Maine, October, 1893. See table 32, No. 2, for further details.
This and the immature or adolescent lobsters represented by plates 8-13, figs. 9-18, were collected
in Casco Bay, Maine, in Small Point Harbor and vicinity, from August 31 to October 19,1893.
The photographs were all made from the alcoholic specimens. ‘They are described in table
32, pp. 163-165. All are life-size.
Fig. 10. Immature male lobster; length 40.3 mm, (1.59inches). See No.1, table 32. Theright cutting-
claw is smaller than is normal, due to the fact that it has been recently cast off and is
now only partially restored. (See Chapter IV.)
ig. 11. Immature female lobster; length 64 mm. (2.5 inches). No.7, table 32.
Fig. 12. Immature male lobster; length 58 mm. (2.28 inches). No.5, table 32.

PLATE 9.

Fig. 13. Immature female lobster; length 75.6 mm. (2.98 inches). No. 16, table 32. The right cutting-
claw is smaller than normal. See fig. 10, pl. 8, with description given above. From
photograph; life-size.

Fig. 14. Immature male lobster; length 67 mm. (2.64 inches). No.8, table 32. From photograph;
life-size.

PLATE 10.

Fig. 15. Immature female lobster; dorsal view; length 86.5 mm. (3.41 inches). No. 21, table 32. From
photograph; life-size.

PLATE 11.

Fig. 16. Ventral view of immature female lobster shown in plate 10. Length 86.5 mm. (3.41 inches).
No. 21, table 32. From photograph; life-size. The seminal receptacle is seen between the
third pair of walking legs. The normal rudimentary condition of the first pair of swim-
merets is also well shown. Compare with plate 7.

PLATE 12.

Fig. 17. Immature male lobster; length 92.3 mm. (3.64 inches). No. 23, table 32. From photograph;
life-size.
PLATE 13.

Fig. 18, Immature male lobster; length 110 mm. (4.34 inches). No.32, table 32. From photograph;
life-size.
PLATE 14.

Fig. 19. Male lobster showing abnormal, symmetrical development in large claws. Instead of the
usual differentiation of the great claws, one for crushing, the other for cutting (well
shown in fig. 6, pl. 5), both are here similar and belong to the cutting type. Length 10
inches; taken at Woods Hole, Massachusetts. Seep. 144. From photograph from alcoholic
specimen; about four-fifths life size.

PLATE 15.

Fig. 20. Right crushing-claw of lobster, probably a male, preserved in the museum of the Peabody
Academy of Science, Salem, Massachusetts: Estimated weight of live lobster, about 25
pounds; weight of skeleton of claw (including the fifth joint or carpus), the parts shown
in the drawing, 163 ounces. Natural size.

Fig. 20a. Right crushing-claw of female lobster, of about average size; length 11 inches; weight 14
pounds; shellfairlyhard. Captured at Woods Hole, Massachusetts, July 24,1894. Natural
size.

This drawing of the claw of a lobster of average size, placed by the side of the mammoth speci-
men for the sake of comparison, shows more forcibly than words or figures can the great
ditference in size which may exist. between adults of the same species. Both drawings
are life-size, and to insure accuracy their outlines were carefully traced from the objects
themselves. The living weight of the smaller claw (including the entire limb) was about
10 ounces, that of the larger about 10 pounds. (See p. 115.)

240

eFig.

Fig.

Fig.

Fig.

Fig.

22.

. 23.

. 24.

30.

. ol.

BULLETIN OF THE UNITED STATES FISH COMMISSION.

PLATE 16.

. Red female lobster, colored from life. Length 112 inches; weight about 2 pounds. Captured

in the vicinity of Mount Desert, Maine, April, 1894. An examination of the reproductive
organs showed that the lobster had not yet reached sexual maturity. For photograph of
this lobster see plate 3. A trifle under one-half life-size.

Adult male lobster, colered from life. Length 10 inches; weight about 1} pounds; shell mod-
erately hard. Woods Hole, Massachusetts, August 14,1891. About two-thirds life-size.

PLATE 17.

Eggs of lobster showing an unusual color variation. Drawn from life. The embryo was
somewhat past the egg-nauplius stage. The lobster, which was 12} inches long and
weighed 2 pounds 5 ounces, was captured at Woods Hole, Massachusetts, December 4,
1893, and sent to me alive. These eggs turned a very light salmon-color when boiled, Six
times natural size.

Cluster of fresh eggs of lobster, colored from life. Laid in aquarium at the United States
Fish Commission station, Woods Hole, Massachusetts. Drawn August 11, 1893. When
first examined the eggs were closely adherent, and the glue which bound them together
was very soft. The ovary of the lobster was examined on August 17; it was of small size,
and contained but few unextruded eggs, which were partially absorbed. About 6 times
natural size.

5. Cluster of egg embryos from swimmerets of female shown in plate 7. Drawn from life

December 7, 1893 The entire mass of eggs are attached to each other and to the set or
hairs of the swimming feet, as shown in the drawing. A single detached seta with a
number of eggs glued to it is here represented. About 13 times natural size.

. Profile view of embryo released from eggshell; taken from a cluster like that in fig. 25.

Drawing made December 12, 1893, after killing the embryos with hot water. Embryos
from the same lobster (see fig. 8) lived eight days in damp seaweed, in a cool room, and
could apparently have been kept alive under the same conditions for a much longer time.
Enlarged 33 times.

. Side view of embryo, as seen through the transparent shell. Drawn and colored from life.

Eggs from same batch as those shown in fig. 25; female represented by plate 7. The
conspicuous green yolk, which is restricted to the upper half of the egg, fills the cavity
of the mid-gut. This eventually forms the “liver” or gastric glands, the anterior lobes
of which are clearly seen in fig. 28. The clear space to the right (on the lower side in
fig. 28) represents the heart. Below it the intestine joins the mid-gut. The eye is shown
as it appears in reflected light in fig. 27, as in transmitted light in fig. 28. (See p. 169.)
Enlarged 33 times.

. Dorsal view of embryo shown in fig. 27. Enlarged 33 times.

PLATE 18.

. Lobster hatching. Drawn from life July 5, 1891. The membrane of attachment (secondary

egg membrane) has split along the middle line and is being drawn off over the head. The
inner part of the shell (primary egg membrane or ‘‘chorion”) invested the embryo as an
exceedingly delicate, transparent membrane, and was ruptured (above the eyes) by needles
in order to show it. When the outer membrane is borne away it usually drags the deli-
cate inner one with it. Enlarged 33 times.

Lateral view of a lobster, teased from an egg which was about ready to hatch, to show the
embryonic cuticle which must be shed before the first swimming larval stage is reached.
The healthy embryo sheds this skin either at the time of its escape from the eggshell or
very soon after it. The intestinal concretions are clearly seen in both this and the pre-
ceding figures. The pigment cells of the skin and other details are purposely omitted.
Drawn from life. Enlarged about 33 times.

Profile view of lobster in fifth stage. General color reddish-brown. Pigmentation of skin
not represented. Rudimentary exopodites of thoracic appendages present. Length
16mm. July 2, 1891. Enlarged 9 times.

Fig. 32.

THE AMERICAN LOBSTER. 241

PLATE 19.

First swimming stage of the lobster, usually called the first larva or the first schizopod
stage. Dorsal view. Drawn from life July 3, 1890. The bright vermilion pigment cells
or chromatophores of the skin are here expanded under stimulation. Under some condi-
tions they contract, and the animal becomes very pale-blue, in consequence of the blood
pigment. The stomach-bag on the middle line behind the eyes, the lobes of the yellow
“liver” on either side of this, the heart behind the stomach, and the intestine passing
beneath this from the stomach to the hinder end of the body, are clearly discerned through
the transparent shell. The yellow cast of color is rather too pronounced, especially in the
abdomen. For color of eyes, see p. 169, and fig. 27. Length about 7.8 mm. (4; inch).
Enlarged 22 times.

PLATE 20.

Fig. 33. Profile view of the first larva of the lobster. Length about 8 mm. July 22, 1891. The trans-

Fig. 34.

Fig. 35.

Fig. 36.

Fig. 38.

parency of these larve is often very great, and many of the organs, such as the heart,
gills, and alimentary tract, are seen with great clearness through the shell. (Compare
fig. 32.) The “‘liver” or gastric gland, usually of a golden-yellow color and resembling a
cluster of grapes, is the most voluminous and conspicuous of the internal organs. The
shading by stipple in this and the two following plates is purely conventional, no attempt
being made to represent the pigmented skin. Enlarged 30 times.

PLATE 21.

Second larva; profile view; drawn to the same scale as fig, 33. The second larval stage is
preceded by the second molt. Beside the striking increase in size in all the parts of the
body, the most important changes are the growth of the antenne and the appearance of
rudimentary legs or swimmerets on the under side of the abdomen—upon the second
to fifth somites, inclusive. Length about 9 mm. (0.35 inch). Enlarged 30 times.

PLATE 22.

Third larva; lateral view. Drawn July 15, 1891. The principal changes which are empha-
sized at the third molt concern the antennie, the growth of the thoracic appendages, chiefly
seen in the large claws, and the acquisition of the last pair of abdominal appendages,
which, with the telson, constitute a very important locomotor organ, the propeller or
tail fan, Length 11.1 mm. (0.44 inch), Enlarged 22 times.

PEATE EZO:

Fourth larva; dorsal view. Length 14.6mm. Drawn and colored from life August 7, 1891.
This represents the average normal color of this stage, yet, as will be seen in Chapter
XI, this is subject to considerable variation. The brilliant peacock-green or intense
yellow-green spots upon the carapace and abdominal segments are characteristic of this
period, but it is difficult to represent these pigments in their natural glow and purity.
Enlarged 104 times.

PuLatTE 24,

. Sixth stage; dorsal view. Outline from a young lobster 15.3 mm. iong, July 14, 1891; color-

ing from lobster No. 3, table 34, in sixth stage raised from fourth larva; length 15.5 mm.
Enlarged 8,3; times.
PLATE 25.

Young lobster in sixth stage; profile view. Raised from the egg; lobster No. 36, table 34.
Length 16 mm. Drawn and colored from life July 30, 1892. The white spots or tendon-
marks on the carapace are very characteristic of this period. They are somewhat less
prominent in the fifth stage. The fifth stage usually resembles the sixth very closely,
particularly in color, Enlarged 11} times.

F. C. B. 1895—16

242

Fig.

ig. 40.

39.

41.

. 42,

. 43.

. 44,

. 50.

51.
52.
r. 53,
. Front view of mouth and surrounding parts—labrum, metastoma, and mandibles—of first

BULLETIN OF THE UNITED STATES FISH COMMISSION.

PLATE 26.

Young, immature lobster; male. Length47 mm. Drawn and colored from nature July 18,
1891. This animal was injured and brought up by accident in a lobster pot in Woods
Hole Harbor. (No. 22, table 33.) Enlarged 23 times.

PLATE 27.
[The stage or molt to which each drawing belongs is shown by roman numerals on plates 27 to 35.]

Right first antenna of first larva, from below. The inner branch or flagellum of this append-
age is now present as a very small unsegmented rudiment, which grows out of the pri-
mary stalk from its under side toward the middle line. 36 times natural size.

Left first antenna of second larva, from below. Segmentation of flagellum of exopodite not
yet visible, or but faintly marked; endopodite tipped with one long and one or two short
sete; shows slight traces of segmentation. Nine bunches of olfactory sete present, 4 to
6 in a bunch, distributed in two longitudinal rows. 36 times natural size.

Left first antenna of third larva, from below. Segmentation of flageila more marked. Outer
and inner branches separated by pressure. 36 times natural size.

Left first antenna of fourth larva, from above. Masses of brown pigment are seen in the
auditory chamber. Segmentation of parts very distinct. au, auditory organ. 36 times
natural size.

Left first antenna of fifth stage, from below. Lobster No. 3, table 34. Parts shown in
natural position. 36 times natural size.

. Right first and second antenne of first larva, from above. Inner edge of exopodite of first

antenna bears a fringe of 22 to 23 plumose setie. 36 times natural size.

. Right second antenna of second larva, from above. 36 times natural size.
. Left second antenna of third larva, from above. 36 times natural size.
. Left second antenna of fourth larva, from below. Flagellum divided into 40 segments. 36

times natural size.

. Proximal portion of left first and second antenne of lobster in fifth stage, seen from below.

Lobster No. 28, table 34. Drawn without pressure. g7, papilla on which green gland
opens. 36 times natural size.

PLATE 28.

Left first and second antenne of fifth larva, as seen fromabove. From lobster No. 28, table 34.
36 times natural size.

Right first maxilla of first larva, from anterior face. 153 times natural size.

Terminal joint of left fifth pereiopod of first larva from anterior side. 50 times natural size.

Tip of endopodite of first maxilla of first larva. 45 times natural size.

larva. Dark-red chromatophores occur on the mandibles and labrum. The mandibular
palp sometimes carries two sete at its tip. 154 times natural size.

. Right mandible of fourth larva, from behind, showing groove and cutting edge. 36 times

natural size.

. Left mandible of fourth larva, from outer side. Hard, chitinous part next to cutting edges,

bluish steel color. 50 times natural size.

. Mandibles of fifth larva, from anterior side. Drawn from the molted shell of lobster No. —

23, table 34, August 10, 1892. Length of larva before molt 13 mm. 36 times natural

size.
PLATE 29.

. Left first maxilliped of first larva, from the inner side. 125 times natural size.
. Left first maxilliped of fourth iarva, from outer side, showing tegumental glands in second

segment (basis). 52 times natural size.

. Right second maxilla of first larva, from outer side. 153 times natural size.
. Right first maxilla of fourth larva, from inner side. 52 times natural size.
. Right first maxilla of fifth larva, from outer side, showing tegumental glands in second

segment (basis). Drawn without pressure, From lobster No. 27, table 34. 50 times
natural size,

Fig. 67.

ey
as
ge
D
ee

THE AMERICAN LOBSTER. 243

PLATE 30.

33. Left second maxilliped of first larva, from anterior face. Epipodite is developed on basis;

no distinct podobranchia. 50 times natural size.

if. Left second maxilliped of fourth larva, from anterior face. Podobranchia present, but rudi-

mentary as in theadult. 36 times natural size.

>. Right third maxilliped of fourth larva, from dorsal surface, natural position. 22 times

natural size.

. Left first pereiopod of first larva, from below. The arthrobranchie which issue from the

membranes between the body and appendage, and are sometimes torn off with the latter,
are also shown in fig.65. 52 times natural size.

Left first pereiopod of fourth larva, from below. The small tubercles of the chelie are
scarcely visible in this position. The exopodite (compare fig. 66), now a short rudiment at
the base of the appendage, does not entirely disappear until the fifth molt. 22 times
natural size.

. Part of left third maxilliped of fourth larva, from below, showing serrated inner margin of

third segment. 22 times natural size.

. Left third maxilliped of first larva, from above. 50 times natural size.

GATE) ole

. Left fourth pereiopod of first larva, from above. 50 times natural size.
. Serrated spine from propodus of left second pereiopod of fourth larva. 153 times natural size.
. Telson of embryo with eye pigment, July 26. Picro-sulphuric acid preparation; teased from

ege in glycerin. 22 times natural size.

. Right second pereiopod of first larva, from the side. 50 times natural size.

. Left second pereiopod of fourth larva, from above. 22 times natural size.

5. Left fifth pereiopod of fourth larva, from above. 22 times natural size.

. Left fourth pereiopod of fifth larva, from above. The podobranchia with epipodite, the arthro-

branchiz and the pleurobranchia are here shown. 30 times natural size.

. Antennie of embryo, the telson of which is shown in fig. 72. 22 times natural size.

PLATE 32.

. Bud of first left abdominal appendage of fifth larva; length of larva 14 mm. Drawn from

molted shell of lobster No. 36, table 34. July 30, 1892. 63 times natural size.

. Seminal receptacle of female. Lobster No.17, table 33. Length of lobster 35 mm. 14 times

natural size.

. Left first abdominal appendage of lobster No. 37, table 34; eighth stage; length 19.75 mm.

(0.78 inch); raised from egg. 63 times natural size.

. Ventral view of young female lobster; length 51.8 mm. (2.04 inches); No. 19, table 33. The

seminal receptacle is here shown in process of development. Compare with plate 11. 5.3
times natural size.

2. Left first abdominal appendage of the sixth stage of development. From lobster No. 34,

table 34. Drawn from molted shell. Length of lobster in sixth stage 16.3 mm. 63 times
natural size.

. Left first abdominal appendage of lobster No. 34, table 54, in seventh stage. Length of lob-

ster 18 mm. (0.71 inch). 63 times natural size.

. Left first abdominal appendage of lobster in sixth stage. No. 36, table 34; length of lobster

16mm. 63 times natural size.

. Left first abdominal appendage of female in eighth stage. Lobster No. 3, table 34. Length

of lobster 21.2mm. Appendage segmented into two parts. For ventral view of thorax of
this lobster see fig. 89. 63 times natural size.

. Left first abdominal appendage of female. Lobster No. 17, table 33. Length of lobster 35

mm. (1.39 inches). 14 times natural size.

. Left first abdominal appendage of male. No. 18, table 33. Length of lobster 36.3 mm. (1.43

inches). 14 times natural size.

. Left first abdominal appendage of female. No. 19, table 33. Length of lobster 51.8 mm.

(2.03 inches). For seminal receptacle of this lobster see fig. 81. 14 times natural size.

244

Fig. 89.

Fig. 90.

Fig. 91.

Fig. 96.

Fig. 97.
Fig. 98.
Fig. 99.

Fig. 100.

BULLETIN OF THE UNITED STATES FISH COMMISSION.

Ventral view of female lobster in eighth stage. From lobster No. 3, table 34. Length of lobster
21.2 mm. (0.83 inch). For first abdominal appendage of this lobster, see fig. 85; for color
in sixth stage, see pl. 24. 5.3 times natural size.

Left first abdominal appendage of young male. Length of lobster 19.3 mm. (0.76 inch)
eighth stage. August 14, 1892. 63 times natural size.

Ventral view of young male. No. 1, table 32. Length of lobster 40.3 mm. (1.59 inches.)
3.5 times natural size.

PLATE 33.

. Left cheliped of fourth larva (No. 23, table 34) in process of regeneration from stump, seen.

from below. Length of larval3 mm. Drawn from molted shell of fourth larval stage
August 9, 1893. X, plane of fracture. 7-7, segments of limb. 22 times natural size.

3. Left fourth pleopod of second larva, from outer face. 95 times natural size.

Left second pleopod of third larva, from outer face. 36 times natural size.

. First abdominal segment of shell of lobster No. 34, table 34, in sixth stage, seen from behind.

Raised from egg, and followed from third larval stage. Length of lobster 16.3 mm. A
colored drawing of this lobster is given in fig. 38, plate 25, and a drawing of the first
abdominal appendage in fig. 82. 16 times natural size.

Left cheliped of molted shell of fifth larva, seen from above. Regenerated from the condi-
tion shown in fig. 92 after the intervention of asingle molt. X, plane of fracture. 7-4,
segments of limb. 22 times natural size.

Left second pleopod of fourth larva, from anterior face. end, endopodite. 36 times natural
size.

Sterna of the last three thoracic somites of fifth larva. From No. 36. table 34. Length of
lobster 14 mm.; sex doubtful. July 30, 1892. 47 times natural size.

Left fourth pereiopod of fourth larva, in process of regeneration. No. 23, table 34. Length
13mm. 7-7, segments of limb. 22 times natural size.

Right second antenna of lobster in seventh stage, in process of regeneration, seen from above.
No. 34, table 34. Drawn from molted shell, August 8, 1892. 22 times natural size.

PLATE 34.

)1. Respiratory organs of second larva, from left side. 8-14, appendages of corresponding

somites of body. 36 times natural size.

. Telson of second larva, from above. 36 times natural size.
. Telson of first larva, from above. 50 times natural size.

Caudal fan of third larva, from below. 36 times natural size.
Caudal fan of fourth larva, from above. Alcohol-glycerin preparation. Set allplumose. 30
times natural size.

. Podobranchia of left second pereiopod of lobster, probably in fourth stage, from inner side.

The gill now carries four rows of branchial filaments. 36 times natural size.

PLATEV35.

. Left first antenna of the embryo shown in figs. 27, 28, plate 17. Frontal view. 63 times

natural size.

. Right second antenna of the same embryo, from below. 63 times natural size.

Rostrum of second larva, from above. 37 times natural size.

. Profile view of carapace of first larva. 13 times natural size.

Profile view of carapace of second larva. 13 times natural size.

. Profile view of carapace of third larva. 13 times natural size.
. Profile view of carapace of fourth larva. From molt, July 15. Dorsal view of same given

in fig.115. The entire outer surface is now studded with short sete. 13 times natural size.

. Profile view of carapace of fifth larva, showing tendon marks. General color of larva

brownish-green; carapace brown. 6 times natural size.

. Dorsal view of carapace of fourth larva, from molted shell. Profile view of same is given

in fig. 113. The median area of absorption is now a broad band which widens in the
rostral regions and unites with the cervical groove on either side to form a cross-shaped
figure. 13 times natural size.

- THE AMERICAN LOBSTER. 245

PLATE 36.

Fig. 116. Section of reproductive organ of embryo near time of hatching. 513 times natural size.

Fig. 117. Section of right reproductive organ of first larva. .0O., reproductive organ. 513 times
natural size.

Vig. 118. Right second antenna of an adult female lobster, overgrown with algw (chiefly Ulva and
Laminaria), seen from above. Length of lobster about 10} inches Taken from lobster
pound at Vinal Haven Island, Maine, August 26, 1893. Two-thirds natural size.

Fig. 119. Oviduet and part of ovarian lobe from left side, showing a row of unextruded eggs in duct.
Length of female about 10 inches. External eggs in yolk segmentation. Woods Hole,
Massachusetts, August 3, 1894. od, oviduct. Two-thirds natural size.

Fig. 120. Reproductive organs of adult male lobster from above. Duct of testis in natural position
on right side, dissected out on the left. Dotted lines (7 to 5) mark planes of section of
the vas deferens and refer to figures on plate 37. a, proximal segment; b, glandular
segment; c, ductus ejaculatorius ; in, intestine; gg, gastric gland. Two-thirds natural size.

Fig. 121. Disk-shaped concretion, probably containing glycogen, from maxilla; cracked by pressure.
133 times natural size.

Fig. 122. Large granular cell from first maxilliped, probably glycogenous in function. August 17, 1893.
733 times natural size.

Fig. 123. Reproductive organs of adult female dissected out, viewed from above; ovary nearly ripe.
Length of lobster 102 inches. No. 77, table 20. August 21, 1890. od, oviduct. Two-
thirds natural size.

PLATE 37,

Fig. 124. Transverse section of proximal end of vas deferens of adult lobster. Plane of section marked
1” in fig. 120. Duct filled with sperm; lining-epithelium consists of small flat cells. This
and figs 125-128 are from the same organ and illustrate the anatomy of the different parts of
themale duct. sp, sperm cells; mb, connective tissue sheath of duct. 36 times natural size.

Fig. 125. Transverse section of vas deferens of adult lobster. Plane of section marked ‘‘2” in fig. 120.
ep, epithelial lining of duct. 36 times natural size.

Fig. 126. Transverse section of vas deferens of adult lobster, showing thick muscnlar walls. Plane
of section marked ‘‘4” in fig. 120. ce. mu, circular muscles; /. mu, longitudinal muscles;
Bl, S., blood sinus. 36 times natural size.

Fig. 127. Part of transverse section of vas deferens, in plane marked ‘‘5” in fig. 120. bm, basement
membrane; ¢c. mu, circular muscles; ep, epithelial lining constituting the spermatophoral
glands; 1. mu, longitudinal muscles; mb, membranous sheath. 190 times natural size.

Fig. 128. Part of transverse section of vas deferens through glandular portion, in plane marked ‘‘3,”
fig. 120, showing spermatophores, contained sperm and glandular lining-epithelium. The
gelatinous spermatophore is a secretion of the latter. a,b,compartments of duct; f/f,
inward fold of epithelium of duct; Sp, sperm; Spr, inner gelatinous substance of sperma-
tophore. 36 times natural size.

Fig. 129. Ripe sperm cells: b,c, from the vas deferens of an adult male and a, from the seminal
receptacie of a female. About 550 times natural size.

PLATE 38.

Fig. 130. Seminal receptacle of adult female, from above. Natural size.

Fig. 131. Ovaries of immature lobster, seen from above. Length of lobster 44 mm. (1.73 inches).
Length of ovary 15 mm.; diameter of lobe +mm. From No.2, table 32. Color opaque
white. Oviducts, though undoubtedly present, not seen in dissection. Natural size.

Fig. 132. Ovaries of immature lobster, seen from above. Length of lobster 74.5 mm. (2}2 inches).
Length of ovary 41 mm.; diameter of lobe 1mm. From No. 98, table 20. Natural size.

Fig. 133. Egg teased from fresh ovary shown in fig. 138. Represents relative size of ovarian eggs one
year older than those shown in fig. 134. 44 times natural size. ;

Fig. 134. Ova teased from fresh ovary shown in fig. 136. Drawn to same scale as fig. 133. This illus-
trates the size at the time of egg-laying of the immature eggs which are to form the next
generation, and which will be ready for extrusion two years hence. One year later they
attain the relative size shown in fig. 133. 44 times natural size.

Fig. 135. Ova teased from fresh ovary shown in fig. 137. The difference in relative size between these
eggs and those shown in fig. 134 represents a growth of about six weeks in summer,
44 times natural size.

246 BULLETIN OF THE UNITED STATES FISH COMMISSION.

Fig. 186. Ovary immediately after egg laying, seen from below. From lobster No. 52, table 20. The
oviducts are filled with unextruded eggs; a few of these ova are also seen in the ovaries.
Immature eggs from this ovary are shown in fig. 134. The yellow flecks are the remains
of unextruded eggs of a former egg generation; that is, they have been in the ovary two
years at least. Drawn in natural size and color from life. July 28, 1891.

Fig. 187. Ovary of lobster No. 87, table 20, bearing external eggs. The latter have been laid about
six weeks (date of laying about July 10). The ovarian eggs possess a dark-green core and
lighter periphery. At the period of ovulation they are colorless, as shown in figs. 134
and 136. August 21, 1891. Drawn in natural size from life.

Fig. 138. Ovary of female which has recently hatched a brood. Taken July 30,1891. For description
of lobster see No. 95, table 20. The pea-green color is characteristic of the ovary at this
time. The contained eggs, one of which is shown in fig. 133, are approximately one vear
old. The difference in relative size between the ova shown in figs. 133 and 134 thus
represents a year’s growth, while the relative difference in size between the ova shown in
figs. 134 and 135 represents only six weeks of summer growth.

We thus see that a generation of ovarian ova grow very rapidly during the first sum-
mer following the last ovulation. They then enter upon a period of quiescence, growing
but slowly, like the external embryos during the succeeding winter. The second summer
following ovulation is marked by a second period of rapid growth, followed in turn by a
second period of quiescence during the succeeding winter. At the beginning of the third
summer after ovulation this generation of eggs is ready for extrusion. That the spawn-
ing periods are thus two years apart is a valid inference drawn from the study of the
anatomy of the reproductive organs. Yellow spots mark as before the remains of degen-
erate eggs which failed of emission at the last reproductive period. The characteristic
condition of the ovary shown in this drawing proves that annual breeding is an
impossibility. Drawn in natural size and color from life.

PLATE 39.

Fig. 139. Part of transverse section of ovary of lobster, No. 52, table 20, with external eggs in early
segmentation, the ova having been laid about thirty-six hours. The peculiar glandular
organs are now seen in the peripheral parts of the lobes. O. G., ovarian gland; O. JV,
wall of ovary. 36 times natural size.

Fig. 140. Part of transverse section of ovary of lobster No. 94, table 20. Glands absent; ovaries
approaching maturity. 36 times natural size.

Fig. 141. Part of transverse section of nearly ripe ovary, from lobster No. 75, table 20. August 19, 1890.
The nucleus or germinal vesicle is shown in one of the nearly ripe eggs. (For more
detailed drawing of nucleus, see fig. 160.) Bl. S., blood sinus; Ct, nodule of connective
tissue. O. G., ovarian gland 22 times natural size.

Fig. 142. Part of transverse section of ovary of lobster No. 52, table 20, showing follicle cells which
have wandered into the egg and are undergoing degeneration. Dg, vesiculated masses of
chromatin, the fragments of degenerated cells; Bl. S., blood sinus containing blood
cells. 457 times natural size.

Fig. 143. Part of transverse section of ovary, the same as in fig. 141, showing the gland-like organs.
Bl. S., blood sinus (dotted line should be continued across gland). 211 times natural size.

PLATE 40,

Fig. 144. Right pleopod of adult female lobster, seen from posterior surface. Drawn from alcoholic
preparation, with camera and dissecting microscope, the cuticle being removed from one
side to show distribution of cement glands in swimmerets. 4 times natural size.

Fig. 145. Fold of glandular epithelium from transverse section of ovary of lobster No. 75, table 20.
From same as fig. 141. ys, body resembling yolk spherule. 190 times natural size.

Fig. 146. Transverse section of lobe of ovary shown in fig. 131, plate 38. From No. 2, table 32. 67
times natural size.

Fig. 147. Part of transverse section of ovarian lobe from a lobster with external eggs near the point
of hatching. The condition of this ovary closely corresponds to that shown in fig. 138.
June 30, 1890. Bl. S., blood sinus. 36 times natural size.

THE AMERICAN LOBSTER. 247

Fig. 148. Part of transverse section of ovary of lobster No. 51, table 20, showing the inner or primary
egg membrane (shaded dark), and the follicular epithelium by which itissecreted, LI. S.,
blood sinus. 211 times natural size.

Fig. 149. Part of transverse section of ovary of lobster No. 52, table 20, showing part of an egg and
follicular cells in contact with it. Those which have wandered into the yolk after-
wards degenerate. The external eggs borne by this lobster were in an early stage of
segmentation. /f. ¢., follicle cells immersed in the yolk. 211 times natural size.

PLATE 41.

Fig. 150. Degenerating cells from the ovary of lobster No. 76, table 20. The larger body to the left is
the remains of what was once a mature egg, which having failed of emission at the time
of egg-laying has suffered degeneration. The tough egg membrane seems to defy com-
plete absorption. To the unaided eye such an egg appears as a yellow fleck, if visible at
all (see fig. 136). 540 times natural size,

Fig. 151. Part of horizontal section of ovary from lobster No. 76, table 20, showing ova inclosed in
folds of follicular epithelium. This ovary was slit open along the mid-dorsal line, pinned
out, hardened, and sectioned in longitudinal, horizontal planes. 67 times natural size.

Fig. 152. Part of transverse section of ovary of lobster No. 52, table 20, showing the developing ovum
and its relation to the folds of glandular epithelium. Remnants of degenerating cells can
bedetectedin this egg. (See figs. 139 and 149.) B. M., basementmembrane; BI. S., blood
sinus; G. £., glandular epithelium. 281 times natural size.

Fig. 153. Glandular epithelium from transverse section of ovary of lobster No. 75, table 20. I’. G.,
vacuoles, probably representing fatty globules which have been removed in the process of
preparing the tissue for sectioning; ys, bodies resembling yolkspherule. 253 times natural
size.

PuaTE 42.

Fig. 154. Ovum in early stage of growth, from ovary of lobster No. 52, table 20. Diameter of egg
jy mm., of nucleus -;1nm. 353 times natural size.

Fig. 155. Young ovum from same ovary as the last. Diameter of egg ;); mm., of nucleus 34; mm. 353
times natural size.

Fig. 156. Young ovum from same ovary as the last. This nucleus contains two nucleoli. Diameter
of egg 1; mm., of nucleus 3; mm. 353 times natural size.

Fig. 157. Young ovum from same ovary as the last. Diameter of egg a little over ;4 mm., of nucleus
j>mm. 353 times natural size.

Fig. 158. Nucleus of ovum from transverse section of ovary of lobster with external eggs about to
hatch. From same as fig. 147. Diameter of egg \% mm., of nucleus y}; mm. 353 times
natural size.

Fig. 159. Nucleus of ovum from nearly ripe ovary of lobster No. 94, table 20. See fig. 140 for ovarian
section. Diameter of egg 1{mm., of nucleus ;}-mm. 353 times natural size.

Fig. 160. Nucleus of ovum from ovary of lobster No. 75, table 20. For ovarian section and position
of nucleus, see fig. 141. Ovary ripe. Diameter of egg 1? mm., of nucleus 4; mm. 353
times natural size.

Fig. 161. Nucleus of egg in process of emitting polar cells. From section of unextruded egg taken
from the oviduct. Diameter of egg 1.31 mm., of nucleus 4 mm. The nucleus is in process
of karyokinesis and lies close to the surface of the egg. The axis of the nuclear spindle
appears somewhat oblique to the surface. July 28, 1891. 353 times natural size.

Fig. 162. Bifurcated rostrum of lobster taken at Woods Hole, Massachusetts. Dorsal view. Two-
thirds natural size.

Fig. 163. Profile view of the same. Two-thirds natural size.

Pig. 164. Ovaries of lobster, from below, showing bifurcation in left anterior lobe. Ovary light golden-
yellow color. Ova very immature. May 19, 1892. Two-thirds natural size.

Fig. 165. Part of gastrolith, separated into its constituent spicules, taken fresh from the wall of the
stomach of a lobster nearly ready to molt. For chemical analysis, see No. da of table,
Appendix II. Compare cut 8, plate C. The broad flattened spicule at the lower right-
hand corner of the drawing is from the peripheral convex margin of the gastrolith. 5.3
times natural size.

Fig.

Fig.

Fig.

Fig.

Fig.

ig. 183.

170.

174.

BULLETIN OF THE UNITED STATES FISH COMMISSION.

PLATE 43,

. Bud of right fourth pereiopod in process of regeneration from young lobster probably in

fourth stage. August 3, 1893. 47 times natural size.

. Part of transverse section of oviduct of lobster, with ovary nearly ripe. July 25, 1893. 270

times natural size.

. Part of transverse section of oviduct of lobster, with external eggs in early yolk segmentation.

For a drawing of this ovary see fig. 119, plate 36. August 3, 1894. 270 times natural size.

. Longitudinal section of first, second, and third segments of right first pereiopod of young

lobster in sixth stage. Plane of section shown in cut 15. Length of lobster18mm. The
right cheliped of this lobster was regenerated between the molts of the fifth and sixth
stages. When the animal was preserved, August 17, 1893, the right regenerated cheliped was
slightly smaller and more translucent than the left. No rudimentary tissue out of which
the new limb is differentiated can be detected in the series of sections through plane of
fracture. « y, plane of fracture; 7, 2, 3, segments of limb. About 47 times natural size.

Internal surface of cuticle of second joint (basis) of first maxilla macerated in Béla Haller’s
fluid, showing chitinous tubules of tegumental glands, and characteristic rosettes of what
appears to be calcareous matter. From male lobster 10 inches long. July 31, 1893. 140
times natural size.

. Part of section of gastrolithic plate from female lobster with hard shell. August 10, 1893.

Shown in its natural position in wall of stomach, in fig. 188. Fixed in picro-sulphuric
acid; stained in borax-carmine; embedded in celloidin. GP., cuticular portion of gastro-
lithic plate. The demarcation between the layers is not so sharp as shown in the drawing.
171 times natural size.

. Section of left first pereiopod of lobster 9 inches long, in process of regeneration. Ataa

mass of large disk-shaped concretions, probably of a glycogenous nature, isseen. Compare
figs. 121 and 122. The blackened margins of cuticle on either side of appendage repre-
sent the remains of clotted blood on surface of the stump. About 6 times natural size.

. Section of bud of right first (crushing) cheliped of adult male lobster, showing the columnar

epithelium, the new cuticle, blood sinuses, and connective tissue. Fixed in picro-sul-
phuric acid; stained in Ehrlich-Biondi mixture; embedded in celloidin. August 9, 1892.
47 times natural size.

Part of longitudinal section of first larva through heart (£t.) and right rudimentary repro-
ductive organ (ov), cutting also intestine (in) and gastric glands (gq). 67 times natural size.

PLATE 44,

5. Right fourth pereiopod of adult lobster in process of regeneration, from below. Color,

bright coral red. Two-thirds natural size.

. Stump of right first pereiopod of adult lobster in course of regeneration, from below. Bud

and surface of scar dull white. August 9, 1892. Two-thirds natural size.

. Surface view of membrane between old and new shells of molting lobster. This membrane

is conspicuous at the time of shedding. It is noncellular, but is marked by the cell
impressions of the chitinogenous epithelium. 733 times natural size.

8. Right second pereiopod of adult male in process of regeneration, from below. New append-

age reddish, tinged with blue at the joints. August 4, 1892. Two-thirds natural size.

. Left second antenna of adult lobster in process of regeneration, from above. June 30, 1892.

Two-thirds natural size.

. Antenne of the Isopod, Ligea oceanica, from above; that of the left side in the course of

regeneration. Beaufort, North Carolina, June, 1885. 4.7 times natural size.

. Regenerating left antenna of the-same, showing the new flagellum inclosed in the exoskeleton

of the joint, which serves as a brood pouch. 16 times natural size.

. Left first cheliped of adult lobster in process of regeneration, seen from the inner and

anterior side. Color, bright red, bluish at joints; cuticle thrown into thin creases.
Longitudinal axis of body in direction of arrow. 5.3 times natural size.

Profile view of masticatory stomach of lobster, showing gastrolithic plate, for the structure
of which see fig. 171, plate 43. Lobster with hard shell, approaching the molting time
August 10, 1893. Two-thirds natural size.

Fig.

Fig.

Fig.

. 184.

185.

186.

. 189.

. 190.

. 193.

. 194.

ig. 196.

197.

THE AMERICAN LOBSTER. 249

Profile view of masticatory stomach of male lobster 7.5 inches long. Nearly ready to molt,
showing gastrolith in place in the wall of stomach. For drawings of the gastrolith as it
appears when it is dissected out and separates into its constituent spicules, see fig. 165,
plate 42. Two-thirds natural size.

PLATES 45a and 456.

Molted shell of lobster shown in fig.186. No.1, table 24. This represents the size of the
lobster before the molt. Length 5} inches. Natural size.

The soft lobster, shortly after the shell shown in fig. 185 was cast off. Length, 64 inches.
Natural size. These drawings show the average increase in size which is effected by a
single molt ‘see Chapter III).

PLATE 46.

. Left cheliped of lobster, from below, showing budding and repetition of parts in propodus or

sixth joint.

. Same as fig. 187, seen from above. Both figures from photographs, and both natural size.

PLATE 47.

Part of right crushing-chela of female lobster, 11 inches long, seen from above, showing
budding of dactyl. Woods Hole, Massachusetts, July 15, 1894. Two-thirds natural size.

Propodus of left crushing-claw, from below. This and figs. 191-196 are from specimens in
Peabody Academy of Science, Salem, Massachusetts, all from adult lobsters. Two-thirds
natural size.

. Left crushing-claw, seen from above. Outgrowth from dactyl in horizontal plane; dactyl

closes under propodus. Two-thirds natural size.

. Left crushing-chela, from above. Secondary dactyl bent downward slightly; no teeth;

dactyl laterally compressed. 8S, spine of dactyl in primary symmetry; S', spine of dactyl
in secondary symmetry. This supernumerary appendage probably represents two dactyls
fused together. Two-thirds natural size.

Right cutting-chela, from below. Fingers bent up; dactyls articulate at joint with pro-
podus; primary dactyl and one of the adjacent secondary dactyl united. 8, supernumerary
dactyl in primary symmetry. Two-thirds natural size.

Dactyl of left cutting-claw, seen from below. It is bent horizontally upon itself, into an
angle of about 80°, this being probably due to irregular growth in the regeneration of a
lost part. Two-thirds natural size.

. Chela of second or third pereiopod, from below, showing two supernumerary dactyls.

Two-thirds natural size.

Right dactyl of cutting-chela, seen from outer side. Bifurcating branches bear teeth, which
are not, however, apposed. Two-thirds natural size.

PLATE 48.

Deformed right cutting-claw. Accessory appendage bent downward from horizontal plane
about 50°. The small terminal joint of the superadded part probably represents two
dactyls fused together. S, spine of dactylin primary symmetry; S', spine of dactyl in
secondary symmetry. Two-thirds natural size. 5

. Right cutting-claw. Propodus apparently deformed by the irregular growth produced in

the regeneration of a lost part. Two-thirds natural size.

. Double monster of first larva of lobster. Raised at Fish Commission station, Woods Hole,

Massachusetts, by Professor J. A. Ryder; seen from above. 13 times natural size.

. Double monster of first larva of lobster, from Professor J. A. Ryder. Fusion of the organs at

the anterior extremity has been carried to such a degree that the compound eyes are now
represented by a small median spot of pigment. 13 times natural size.

PLATE 49.

. Gland-cell from tegumental gland of second maxilla. Macerated in Béla Haller’s fluid for

several days, and stained in methyl green. 733 times natural size.

. Gland-cell from same preparation as fig. 201. 733 times natural size.

250 BULLETIN OF THE UNITED STATES FISH COMMISSION.

Fig. 203. Part of macerated tegumental gland from metastoma. Compare also fig. 214. From female
withripe ovaries. August9,1893. Stainedin methyl green. Central cell takes on deepest
stain. gd.c, gland-cell; &, central reticulated body; s.c, ganglion cell. 773 times natural
size.

Fig. 204. Cell from macerated tegumental gland of first maxilla. Stained in methyl green. 773 times
natural size.

Fig. 205. Gland-cell from same preparation as fig. 204. 773 times natural size.

Fig. 206. Cell from macerated tegumental gland of abdominal appendage of female before egg extru-
sion. Ovaries nearly ripe. Attenuated, central end of cell very refractive. Smal
bodies, apparently accessory nuclei, are present in cell. 773 times natural size.

Fig. 207. Same preparation as last, rolled under cover-slip and seen from opposite side. 773 times
natural size.

Fig. 208. Tegumental gland from metastoma of female with ripe ovaries. Macerated three days in
Béla Haller’s fluid and stained in methyl green. The duct (d) of the gland could be seen
to open directly into a small central chamber, as in fig. 212. 518 times natural size.

Fig, 209. Gland-cell from tegumental gland of abdominal appendage of female, which had recently
laid eggs in an aquarium at the United States Fish Commission station, Woods Hole, Mas-
sachusetts. Macerated in Béla Haller’s fluid. August 14, 1893. 773 times natural size.

Fig. 210. Tegumental gland from abdominal appendage of female lobster 10} inches long, preparing to
molt. Chromic acid preparation, stained in the Ehrlich-Biondi anilin mixture. Picro-
sulphuric acid gives same result. Cells apparently shrunken, transparent. non-granular;
nuclei clear. August 17, 1893. 515 times natural size.

Fig. 211. Tegumental gland from abdominal appendage of female after ovulation. External eggs in
yolk segmentation. Central ends of gland-cells are filled with dark zymogen granules.
Nucleus of gland-cell stains green, that of central cell always red, in the Ehrlich-Biondi
mixture. August, 1893. gd.c, gland-cell; s.c, ganglion coll. 513 times natural size.

Fig. 212. Section of tegumental gland from abdominal appendage of female lobster with mature
ovaries. Central part of gland has a bluish clouded appearance. Nuclei may be green or
red according to the degree with which the stain is extracted. Stained in the Ehrlich-
Biondi mixture. August 4, 1893. d, duct of gland; n, nerve-supplying gland; J, central
reticulated body. 513 times natural size.

Fig. 213. Gland-cells from same preparation as figs. 204, 205. Central ends of cells atfenuated, and
strongly refractive. 773 times natural size.

Fig. 214. Macerated tegumental gland from metastoma of female, showing the central reticulated
body, gland-cells, ganglion cell, and duct of gland. From female with ripe ovaries. d,
duct of gland; &, reticulated body. 773 times natural size.

PLATE 50.

Fig. 215. Egg before yolk has segmented. The whitish spots are due to the presence of cells which
are approaching the surface on one side of the egg. The yolk is later massed up about
these in hillocks, as in fig. 218. 29 times natural size.

Fig. 216. Surface view of egg with 16 cells present near the surface, two double rows of eight cells
each.' The cells have just divided. This drawing was made at 10.30 p.m.; at 10.55 p.m.
20 cells could be discerned near the surface. 29 times natural size.

Fig. 217. Same egg as fig. 216; drawing made 1} hours later (12 p.m.), showing the cells more diffused
over the surface. 29 times natural size.

Fig. 218, Same egg as in figs. 216 and 217; rolled to show animal pole and yolk hillocks in profile.
Drawing made at 10.55 p.m., when 20 yolk elevations had been formed. On the outskirts
of these, other cells can be seen lying below the surface and destined soon to become the
centers of new hillocks. 29 times natural size.

Fig. 219. Surface view of egg showing yolk segments in active division; 10.15 p. m., segmentation
furrows complete. This side of egg corresponds to the side shown with yolk hillocks in
profile, in fig. 218. Nuclei all dividing at 10 p.m.; at 10.10 p.m., furrows began to appear,
separating cells. Same egg as shown in fig. 220. 29 times natural size.

Fig. 220. Reverse side of egg shown in fig. 219, corresponding to the right side of the egg shown in
fig. 218, opposite the yolk hillocks. When drawn at 9.30 p. m., nuclei were invisible; at
10 p. m. they were very distinct and in diaster phase; at 10.15 p.m. segmentation furrows
completed. 29 times natural size.

THE AMERICAN LOBSTER. 251

221. Surface view of segmenting egg, under observation 5 hours (8 p.m. to 1la.m.). At 12 o'clock
the segments shown in the drawing were very convex at surface, standing far apart as if
the egg were breaking up. At 1a.m.the segments were closer together and nuclei were
about to divide again. Drawing made at 11 p..m., after completion of division, 29 times
natural size.

222. Surface view of segmenting egg. Drawing begun at 11a.m.; when completed, half an hour
later, the nuclei had divided and segmentation furrows were making their appearance.
29 times natural size.

223. Surface view of same egg, drawn at 12 m. Division of cells mostly completed. 29 times
natural size.

g, 224, Surface view of same egg as in figs. 222 and 223, at 9p. m., in advanced stage of segmen-

tation. At 2.45 p.m. nuclei were dividing; at 6.45 p.m., when examined, division was
completed. Drawing made at 9 p.m. 29 times natural size.

225. Surface view of egg in advanced stage of yolk segmentation. Free-hand drawing. 29 times
natural size.

226. Surface view of egg in abnormal yolk segmentation, showing a larger yolk mass at the lower
part of the figure and a number of smaller regular segments. <A similar large yolk mass
occurs on the opposite side of the egg next to the one shown in the drawing. 29 times
natural size.

PLATE 51.

227. Surface view of egg in invagination stage. August 3, 11.30 a.m. 29 times natural size.

228. Surface view of abnormal embryo in egg-nauplius stage. August 10. 29 times natural size.

229. Surface view of abnormal embryo. August 8. 29 times natural size.

230. Surface view of abnormal embryo in egg-nauplius stage. PP, cells approaching surface;
r, outward fold of surface epithelium; y, yolk. August 9. 29 times natural size.

. 231. Surface view of abnormal embryo in egg-nauplius stage. August 8. 29 times natural size.

232. Lateral view of embryo, showing large white patch behind abdomen. August 5. 29 times
natural size.

233. Lateral view of embryo about 5 weeks old, showing lateral fold of carapace covering the
antennie, the heart (Ht.), the intestine containing characteristic concretions (P), the
telson (7) overlapping brain and optic lobes, and the lateral indentations of the yolk
corresponding to divisions of the midgut. July 29. 48 times natural size.

234. Surface view of embryo about 25 days old, showing the large optic lobes of cephalo-thoracic
appendages. The telson touches the brain, and the crescentic fold of the carapace
extends forward as far as the first maxillipeds. August 3, 1892. 29 times natural size.

. 235. Lateral view of double monster in egg-nauplius stage. August 13. 29 times natural size,

PLATE 52.

,, 236. Part of transverse section of egg in stage between that shown in figs. 224 and 225, yolk cells

(y e) being formed by tangential division, About 70 times natural size.

237. Part of longitudinal section of egg in egg-nauplius stage, showing degenerating cell (Dg).
457 times natural size.

238. Part of section of seginenting egg, showing cell migrating from surface. July 31. 40 times
natural size.

239. Section of segmenting egg, showing yolk cell near center. July 31. 40 times natural size.

240. Degenerating cells from same preparation as shown in fig. 237. ys, bodies resembling yolk
spherules. 457 times natural size.

241. Vesiculated masses of chromatin (Dg) undergoing degeneration in the yolk. From
transverse section of early egg-embryo. July 18. 457 times natural size. .

242. Section of segmenting egg. Drawn July 31,4 p.m.; 34 cells present. 40 times natural size.

243. Section of egg in late segmentation, showing formation of yolk cells and division of these
in yolk. August1. sce,cell at surface undergoing tangential division; y c, yolk cell in
process of division. 40 times natural size.

244, Surface view of ege in late segmentation of yolk. July 11. Fixed in Perenyi’s fluid.
About 50 times natural size.

252 BULLETIN OF THE UNITED STATES FISH COMMISSION.

Fig. 245. Part of transverse section, showing multiple karyokinesis and formation of nests of nuclei.
Stage like that shown in fig. 252. Part of section behind and to one side of invagination
area. Same series as fig. 241. en, cell nest at surface; yn, cell nest in yolk; yn', cell in
multiple karyokinesis, situated in yolk ball. 457 times natural size.

Fig. 246. Part of transverse section through embryo in invagination stage. in, area of invagination.
211 times natural size.

Fig. 247. Part of section of egg to show nest of nuclei at surface. 211 times natural size.
Fig. 248. From section through embryo in invagination stage, showing multiple karyokinesis and

formation of nuclear nests at surface, like that shown in fig. 247. 211 times natural size.
Fig. 249. Part of section of egg containing two nuclei, this one near surface. 285 times natural size.

PrAtH! 53:

Fig. 250. Surface view of embryo in invagination stage. The embryonic area of this egg lies in front
of the shallow pit. Cells are most numerous immediately in front of this depression and
about the extreme anterior margins of the exposed surface. The rapid proliferation of
cells in these regions gives rise on the one hand to the thoracic-abdominal plate, and to
the optic disks on the other. Karyokinetic figures of dividing cells are seen scattered
over the entire sarface of the egg. The equatorial plate is in each case vertical, and may -
make any angle with the longitudinal axis of the embryo, or with a iine drawn through
any proliferating center. Numerous granules, the products of cell degeneration, are
commonly seen. The reverse side of this egg shows nothing peculiar. Nuclei are there
less numerous, and the superficial cells are larger. Flecks or clouds of granules, floating
in the yolk below the surface, are seen here and there with no regularity. The nuclei
over most of the surface, excepting those at the extreme periphery, were drawn by aid of
the camera lucida, as were the cell outlines in the more central parts. From a picro-
sulphuric acid preparation, stained in borax carmine, the egg cut in two, and the
hemispheres mounted in balsam. August 6, 1892. 500 times natural size.

PLATE 54.

Fig. 251. Part of transverse section through area of invagination (in), showing columnar surface cells
(ec) filled with yolk and invaginate cells, lying between and within yolk masses. Some
of the latter cells just below the surface are undergoing degeneration; some in the
deepest parts of the egg are creeping with their long pseudopodia between the yolk
spherules. These play the part of phagocytes and also contribute to the tissues of
the embryo. 360 times natural size.

Fig. 252. Surface view of embryo in region of invaginate area, showing clusters of cells at surface,
produced by inultiple karyokinesis. A, anterior; P, posterior end of egg; Deg, degener-
atine cells; ea, embryonic area; Jn, area of invagination; y n, cell nest, produced by
multiple karyokinesis. 89 times natural size. 0

Fig. 253. Part of longitudinal section of intestine of embryo in a late stage of development, showing
concretions in the lumen of the organ. bm, basement membrane; ep, intestinal epithe-
lium; p, intestinal concretion. 360 times natural size.

Fig. 254. Part of transverse section through invaginate area of an earlier stage than last, showing
in-wandering masses of cells. A, anterior; P, posterior; In, pit of invagination; y ¢,
invaginate cells. 89 times natural size.

Fig. 255. Part of longitudinal section through area of invagination, showing the advancing cumuli
of cells, which are pressing into the deeper parts of the egg and investing large masses of
yolk. The distinctly columnar superficial cells, gorged with yolk, are also shown. In the
embryonic area these become very tall, and beneath them there are clouds of disorganized.
chromatin granules, the remains of degenerated cells. A, anterior; P, posterior; Deg,
degenerating cells; ec, ectoderm; Mes-ent, mesendoderm; Jn, pit of invagination; OD,
optic dise. 89 times natural size.

Fig. 256. Concretion from intestine of an embryo which was nearly ready to hatch. Teased from
picro-sulphuric acid preparation and mounted in glycerin. 360 times natural size.

Bull. U. S. F. ©. 1895. The American Lobster. PLATE 1.

Fg 1.

Irom photograph.
MALE LOBSTER. Weight, 23 pounds

it
i‘

Bull. U. S. F. ©. 1895. The American Lobster. PLATE 2.

From photograph.

VENTRAL VIEW OF MALE LOBSTER. Weight, 23 pounds.
VENTRAL VIEW OF FEMALE LOBSTER, Weight, 1} pounds.

‘Y31S8O71 31IVW34 Linay

aft) Wolf paydy.hopoud

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Bull. U S. F. ©. 1895. The American Lobster. PLATE 4,

hacenil?

Fry. 5.

Photographed from life.

ADULT MALE LOBSTER, Dorsal view.

Bull. U. S. F.C. 1895. The American Lobster. PLATE 5.

Photographed from life.

ADULT MALE LOBSTER. Ventral view.

Bull. U. S. F.C. 1895. The American Lobster. PLATE 6.

Photographed fron life.

ADULT FEMALE LOBSTER WITH EXTERNAL EGGS. _ Dorsal view.

Bull. U.S. F C. 1895. The American Lobster. PLATE 7.

Photographed from life.

ADULT FEMALE LOBSTER WITH EXTERNAL EGGS. Ventral view.

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Bull. U.S. F.C. 1895. The Amencan Lobster, PLATE 8

From photograph. Females. Males.
IMMATURE LOBSTERS. | Natural size.

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Bull, U S F.C. 1895. The Amenican Lobster. PLATE 10.

IMMATURE FEMALE LOBSTER. Natural size. Dorsal view.

From photograph.

Bull. U.S F.C 1895. The American Lobster, PLATE 11.

From photograph.

IMMATURE FEMALE LOBSTER _ Natural size, Ventral view.

Bull. U S. F.C. 1895. The American Lobster. PLATE 12.

From photograph.

IMMATURE MALE LOBSTER. Natural size.

ape sie

A

Bull. US F €. 1895. The American Lobster.

PLATE 13.

From photograph.

IMMATURE MALE LOBSTER. Natural

size

Bull. U.S. F.C. 1895. The American Lobster, PLATE 14.

Fg 19

From photograph.

ADULT MALE LOBSTER WITH ABNORMAL SYMMETRY IN LARGE CLAWS.

PLATE 16.

F. A. Herrick ad nat. del.

Bull, U.S. F.C. 1895. The American Lobster.
PLate 15.

Fig.20.

. Herrick ad nat. del,
: _ RIGHT CRUSHING.CLAWS OF LOBSTERS WHI

gia sp chi a # nee

aji] uo4y Yog -— 2 S801
a@—43tseo] S1VWW Lindy ‘uaisso7 aay aqvWag Linay AERO AD EUROS oF Er

NY
\
‘98 Gee

9) 3iv1d

PLATE IZ

5
1
;
¥
/
|
\
: |
;
i Piga 27: Fig. 28.
i ° h Ai RLS y H Fo
np F H.ferrick ad nat del.

VALERESH DREAD EGOS SENS ADVANCED EMBRYOS.

Meshvans Wy ; Savi

Stay
Ger

ANE
f Ms Rare
ee,
Ne

Wasyes
Na

ONDA eas
i {
ANY ae
rane

i

Hosts aeaarAnyny
v ,

tut

a)
ji Ch

Pion AaNe

yal
vy

i

=

ae

NN h eae
Pati ua AG
Ce Oe Be

lee
Pea
pieseriey

iY MM

bey
Dates

‘hte
die

OSS,
DUS WVaay
NH

Yuet Uae , Wah
TAG os Oe Ue aN read EE
Wi ; NAD
19)

‘S9VLS HLsla NI ONNOA GNV¥ 'T13HS-993 WOYS GSAOWSY VAYVT “DD3 WOYS ONIHOLVH VAYYT
"JAP "]DU PY Youll “HW

“SL 3LvV1d ‘Jaisqo7 uesvawuy aut “G6gl D'4'S ‘Ning

PLATE 19

|

Fig. 32.

LENGTH.

EH. Herrick ad nat.del. THE FIRST LARVA, or First Free- Swimming Stage of the Lobster.

aie

eae es =a oy

U t
Peipumyst

vet x
BAit ed

‘A
ih
Bi
ya
Neate

WSO Gas
a ean

PANE OAG

ae

;
a

Uh
hile
; va

lays

Ne a at
AHR D Ne RORY

PLATE 20.

The American Lobster,

Bull. U.S. F. C, 1895,

aa
NE

cA
¥

aA)

oN

IR, Jel Herrick ad nat. del.

FIRST LARVAL STAGE.

‘ : ¥ ' ' 1 Uae)
: fi : i ial
- 2
- -
aa a i hat} }
‘ — }
i i aoe
: oe
‘
r A: 7 i
_ z
: . 7 :
7 ‘
4
cos it *
: : = = ,
7 ; F
a : i -
2 : : >
: “
. of 7 .
‘ a ‘
- - t
.
= 2 as
: i ‘
~ a F, =
+ = $
: ‘
: ns :
- _ : :
* 4 i 9
mee jay
i fi iat ; . i .
pa
5 oo z ’ Cone ms
7 oe ~> le =
a a S
é :
z : ,
o : A 4 : a ad; :
2 7 ao _ 7 t
: : ; a
y : yi . a U rae
at 4 a ;

a

Mg

ib 5 a
Pi
7 ik *

PLATE 21.

The American Lobster

Bull. U. S. F.C. 1895.

F. A. Herrick ad nat del.

SECOND LARVAL STAGE.

Bull, U. S. F, C. 1895, The American Lobster. PLATE 22.

I, H, Herrick ad nat. del.

THIRD LARVAL STAGE.

FH. Herrick

ad nat.del,

Fig. 36.

Pp ESN

FOURTH FREE-SWIMMING STAGE.

PLATE 23.

LENGTH.

ie
Anite

A Wits k yin

ACA RAL Mrad Ce he

Uairin Rua ENVIR LS
c

(hp):

Hey t
oy

Nw

eee
auld

Mh
uae

muvave Le
aD MAL NS A
( al
oat “AN
Heeritivad AeA
AOR)

a,
Orth) hae
eo bih\oas $Y

Aaa

He Ni

RIN 9

\ v

HG yaon
ay f

Pavol

if) 3 y ‘ \ f A ) 1g?
Mites Pa

OU MOPT FR

nek: riba i

ale X
PONY Lay

Erik

yt) Arata AN
v

Tovey

1h
aot ty

OMA ee,

HEA ie

ea
tM

Bvt
anes |

a
do

PRONG
Mee AR AU
sei

WE

Mi

yall
Wak

i Oct

Rs UA

|

pata
Wei
Wy Pa

\ Wh m\yUy
PINAR CPN LC) A
al) Ose
vy it
sey

vr

tae BARS UP HIN DULUTH ait ra HAC OMMCRTRMMAM MST IND TN Ry
AoE ‘ SO Bee STUeNat ; Rh) y Ks OA aD Byer A Ockyy Mi
rit NPS HEA ( Roa asa aA heater U uh , Helio

oh 4 AW
al 4

PLATE 24n

Fig. 37. f

¥ \\ \ \
4 \ Si
\ \\\ Wi LENGTH.

EH. Herrick ad nat.del. SIXTH STAGE

*

Wainy
tay

ale Kral
Lan

i i f

Te,
(aie
i

Ate
‘
1 } i
<

Mighas ie ni

ian

an

ite
athe
‘ BAAN ai

ies

NRA y Wat
Pore bat ; i URC ye
Heo (hae Ne i eee se YONG RAR tl be ‘ uh ad a 1

Laat
Obie pret)
Res)

er

De
a
beat ia
uae |)
Maehs
Mares

rare)

Oe
NUN
f i

i ay
ya ae i th Y
h f
Ui SURG
i

{epi tee ay pli ait v ; 1 /
Sees SHA Sea THU SON vi Radin
any y
Fase

Wt
1

AAA ULNA

BO VALS EEGs
‘yap you Pv YowtwIy Ho]

aldeloiNistel

-——______,

‘$2 3lV1d

“PIO 4P2A SUOQ-—HIALSEO] AYNIVWWI 12 PROM PO HOMO EL vol

“HLONAT

‘6e Hiy

rab
d

Bull. U. S. F. C. 1895. The American Lobster PLATE 27.
pan LY

fe \N {
\ Q Ww

SS

f. H. Herrick ad nat. del.
MORPHOLOGY OF APPENDAGES.

Bull U. S. F.C. 1895. The American Lobster. PLATE 28.

|

ia, 6 Ss

F. H. Herrick ad nat. del.

MOUTH PARTS AND APPENDAGES OF THE YOUNG.

Bull. U. S. F. C. 1895. The American Lobster,

PLATE 29.

SS

hee } Weteopae
ahi

Ne Lif

y

Ke

A
y)
Wf J,

\ yy
Wipe

MORPHOLOGY OF APPENDAGES.

I’. H. Herrick ad nat. del,

Bull. U. S. F.C, 1895. The American Lobster PLATE 30.

Re :
\4

Ai

YW
ZZ

ZZ77,
Las
an

\

F. H. Herrick ad nat. del.
MORPHOLOGY OF APPENDAGES.

Bull. U.S. F.C. 1895. The American Lobster. PUATEsoilts

IF. H, Herrick ad nat. del.
MORPHOLOGY OF APPENDAGES.

Bull. U. S. F.C. 1895. The American Lebster. PLATE 30.

F. H. Herrick ad nat. del.

DEVELOPMENT OF FIRST PAIR OF ABDOMINAL APPENDAGES AND SEMINAL RECEPTACLE.

Bull. U.S. F.C 1895 The American Lobster, PLATE 33.

I. H. Herrick ad nat. del.

REGENERATION AND DEVELOPMENT OF APPENDAGES.

Bull. U S.F C. 1895. The American Lobster. PLATE 34.

i Liga) ath
iooene |

ig

I iy

ae = i pHa
Biba) 2,
2s ape ;
» GAs
r. ,
vie Vie Any er > *
F } a baas 6
F ¥
i j 7
a4 )

li WW
i WE \

47),
WIS.

|
mY ‘|
{ uM \
f , aA ty
‘a R \} a au
, ie

Fig .105

F. H. Herrick ad nat. del.
MORPHOLOGY OF APPENDAGES AND BRANCHIA.

Bull. U.S. F.C. 1895, The American Lobster PLATE 35.

Wig 113

F. AH. Herrick ad nat. del.

THE CARAPACE AND ANTENNA.

Bull. U. S. F. ©. 1895. The American Lobster.

ay S:
ses —

x

—<$<$<—<—<—$———

Fig. 123

PLATE 36.

Spy

Kee pevinee

FF. H. Herrick ad nat. del.

THE REPRODUCTIVE ORGANS AND OTHER STRUCTURES

1
5

Bull U.S. F C 1895, The American Lobster. PLATE 37.

[ ne iis Fi o

NN

Soe.mu

“LiL be

Yi,
SS

Mii.
di I AN

hata
d, LETIRNSNS

<n eo EN —

MONT

ena

Nag
ate

"

Fig. 129

I’. H. Herrick ad nat. del.
STRUCTURE OF VAS DEFERENS AND SPERM CELLS.

Pt ae
oe cts

“i

THE OVARY AND SEMINAL RECEPTACLE.

Ove)
a1 ANAS,

DAR eon
MYATT
YAU SE

1
i

Ni
Ne

i
ai

yp Fe be
Wi acelon ain hie

ay rite

PEN ey
fit

{|

halite

HRS dian

AUR EN?
ney

Hey Bt

MUL
uty) va
OS )
NRA
SVAN
bes SMO

TES an
ON +

WH
ie

NETIC
YE BSS
it

eta iss
Haw Ae
Gis ‘ 1 enit \ r SARS IT
ain aera Hy H LovLonttannn

DAR avate
Bye Lair Ni

HL

Weert
HAM
;

$y
He

‘G,

veer oii
LOHR?

any i tf
: ENT,
1 b CARRERA IRS he

")
Alf
iH

SERIE okie:
NAAN
Ri ASD We a
Rhea Hi Gee ia
HLA HENS ¢ ‘ PSA Naps Astras} wie
wera SIGMA ESRD) SATE aM NIN AS GAH a

Wat

isc:
Wenge
eae

PLATE 39.

The American Lobster,

Wh Sy [ee ERE

Bull,

I, H, Herrick ad nat. del.

STRUCTURE OF THE OVARY.

a)

i

Bull, U.S. F. C. 1895. The American Lobster.

[

Fig. 149

PLATE 40.

LC.

F. H, Herrick ad nat. del.

OVARY AND TEGUMENTAL GLANDS.

aie i} aU
ea
t
‘
ant AN
oy

Bull, U.S. F.C 1895, The American Lobster PLATE 41.

Ey)

fy

J FP\ SS
ey Mui oa i
1 Se age

1

d a (\eg | ; is i G ‘
yp BMC eae

I’. H. Herrick ad nat. del.
STRUCTURE OF OVARY

Bull. U. S. F.C. 1895 The American Lobster

Fig. 158

HH erichiad natidel

METAMORPHOSIS OF GERMINAL VESICLE, SPICULES OF GASTROLITH, AND OTHER STRUCTURES

PLATE 42.

Bull. U.S. F.C, 1895, The American Lobster.

—

PLATE 43,

=e | | | Uy iy |
i Uj mdi |
Msi

Fig. 173

F. H. Herrick ad nat. del. _

YZ NM aS
May
iy,
Ss Uf wy

Fig. 168

oo
YY)
BYZ
aS
—_—

Nearer eke \'

2 ae

x
Vos
\

REGENERATING LIMBS, THE OVIDUCT, AND OTHER ORGANS,

sro be

ie

Bull. U.S. F.C. 1895. The American Lobster.

oe SS ee ee eee eee = _ PLATE 44.

Fig .178

Fig. 175 Fig. 176

Fig 179

Fig. 183 Fig. 184.

F. H, Herrick ad nat. det.

REGENERATION OF APPENDAGES. THE GASTROLITHS.

Bull. U.S. F. C. 1895. The American Lobster. (To face Plate 45 0.) PLaTE 45a,

ae : |

Fig .185
\ AY \ | a Sv,
l

F. H. Herrick ad nat. del.
CAST-CFF SHELL. Natural size.

PLATE 45>.

:

Bull. U. S. F. ©. 1895, The American Lobster. (To face Plate 45 a.)

Fig. 186

c

mo
as Sort

NY

I, H. Herrick ad nat. del,
SOFT LOBSTER AFTER ESCAPE FROM SHELL SHOWN ON THE LEFT. Natural size

Bull. U.S, F.C. 1895, The American Lobster. PLaTE 46.

—_—_re

io

From photograph.
ABNORMAL CHELIPED. Natural size

Bull. U. S. F.C. 1895. The American Lobster.

PLATE ale

Fig. 192

FF. H. Herrick ad nat. del.
DEFORMED CLAWS.

Bull. U. S. F.C. 1895. The American Lobster. PLATE 48.

= a SS

Mg. 198

Fig 197

Fig. 199

F. H. Herrick ad nat. del.

DEFORMED CLAWS IN ADULT AND DOUBLE MONSTERS IN FIRST LARVA,

Bull. U. S. F.C. 1895. The American Lobster PLATE 49.

Fig. 202

Fig. 204

F, H, Herrick ad nat. del.
STRUCTURE OF TEGUMENTAL GLANDS.

Fig. 224. lig. 226.

FH Herrick ad nat del. SEGMENTATION OF THE EGG. .

PO Oya ss
wit

ven saa ? nla at sass ai COL ete ah ey
Pa EONAR mannan ‘ St ne Bie } OS) SALT Paaaiplesp rane (bean
Wie Olea iy Aas SHIH eben r 4) 4 at ORCC a

) } } v it Weert ok \

Pi
tens
rene

nit ”,
Wate ATT
UAV
Vahey

fi

Cunt
x

MY

Hv py
o ye

ak

ne
nies
HOH
a

:
gras
FTAA ANNSY Lean

MA
lien aiios e
AK

‘ a ih Nees

Mask eh AN Wa 4
ie Ry Zane

i)

POUR,
oN,
i ae i

Sains

Visti
By

iy
my

a

Aye

AY,

4 5

ah . Sash iy,
‘ i Aix > Wy

tat
ISA,

Me

TET ON ay tA,
FICE AD NTA UY aie
ar sO ANY ee
1] Uses Hinles
et
ASNe

i
NAT
ws

mune
Adal ean

ve Wee

nit)
ficserts
Sc

Ms

|
|
|
|

EI, H. Herrick

nat.deb,

THE EMBRYO.

Kent
Penna
Wi

)

Rehan

NAY)

ty

NT

ys

Wy
(|

'

3 arcs
Realty pele
ATA

Viana
RNA
INVA
i

tase ify
Hie
lat iy)

Wns
11

yah

By

Ait yA

Anant 4

ong HN 12, - Hes
{ Mak

CUR

Tain

Kona
PAS
j v

UTS \ ms Ye \ y ‘ wip is 3 ie
MANY * y Hy kph iy Lon

Waiiae
ON i x
IAS Re
eee
ase

/Potbe, fal is)
AN Rt
yg i Sits

Mine

i

Py,
SONY
Me etdy

aay
DXA Vt
GUN Ne

Raendy
ANN

TBO Sa
Ca

ARADANNT Ae

RNa TONY NAY

HIS ve
td

4
PAHS
iN Mi) ton Hse na Ho)
DIANE VASA Me AinIaINeD A Aba jh DM eh A tua, tie Mi ne LMI iy)
ay

Ahn

Bull, U. S. F.C, 1895, The American Lobster. PLATE 52,
mais abies

vy
ey a 7S. |

Fig. 240

EF. H. Herrick ad nat. del.
DEVELOPMENT OF EMBRYO.

PLATE 53.
Bull U.S. F.C. 1895, The American Lobster,

LN Le!
WS,

SOD earc: <<
or Pose. ase

Fis. 250

PF. H. Herrick ad nat, del.

EGG-EMBRYO, INVAGINATION STAGE.

Bull. U.S. F.C. 1895. The American Lobster

2.
4? 08.

O08
one
My

o

3
4
o

©
0% ©

Fig. 255

F. H. Herrick ad nat. del.

DEVELOPMENT OF EMBRYO,

PLATE 54.

ca

Re ec
a iy 7 a ae

WS’ S3INVYSIT LIBRARI ES SMITHSONIAN INSTITUTION NOILMLILSNI_NVINOSHLIWS $3 buvyudiq |
op] > oS M
uu a uw .o us 6 & q
wz ae, rs — IQS RE =
< _ <x = < a RW < |
e : = aN ES 2
= 8 Gi S Zz S aes 2

: <a ; s > |

IAN” INSTITUTION — NOLLA.LULSNI~ = S3/YVYaIT_LIBRARIES— SMITHSONIAN” INSTITUTION 5.
oo S 9 ° = oO 4 = S

y, 0 = 2 5 me & 2 a

th > = z= fe > E es E

ae = = - z Er , Z i
o Z ee = o 2 O |

INS Salyvugi] LIBRARIES SMITHSONIAN INSTITUTION NOILMLILSNI_ NVINOSHLIWS |
a) zfS pad Foe a) z w z

Nee Vi 5 = 3 = 5 = 5

%) w o> D oe 2 B fa B a |

1S a= 2 = Zz = z E
>" = ‘SS a = >" = >" =|

ea 7 n

IAN INSTITUTION NOLLNLILSNI_ NVINOSHLIWS” 2 INSTITUTION
= tp) a o = ” q
7) = 4 OO _ ow - x |

Jpn — ae cay a

a : 2 SY: 2 < <

os E = WO ca = oa a
S ar S nas am S = i!

INS SAINVUGIT LIBRARIES SMITHSONIAN INSTITUTION NOILNLILSNI_NVINOSHLINS S31uvudlq)

3
z Cag = ~ Zz (a a my
5 a = > cade =

| E = bs = ia aah ie

.. Z o ra O Zz On a 2 i,

TAN UTION NOILNLILSNI SIIUVUGIT_LIBRARIES. SMITHSONIAN INSTITUTION |
z : ow 2 a z ce Ze D
<l : = < = x a = z NS i >
z . = = 4 yl Jy = NS = z
oO S ac {e) LLY 4 O Wee ae S) ut »

c 2 E 2 “yy = a =
3 eS ; a z 3 a » 3 = . @

INS SAINVYUGIT LIBRARIES SMITHSONIAN INSTITUTION NOILNLILSNI NVINOSHLINS S3IYVYaIIE
= w = a ras 7 sh

\ = = oe a eS = =
< <x %

em Mee S cc = o ier ec

ee 5 = S e 3 a ?

= as Fa, 2 = z = a3 d

JIANT INSTITUTION ~ NOILALILSNIT SAINVUGIT LIBRARIES SMITHSONIAN INSTITUTION §
z z c z c Fae l= z

© = 4

y wo = jes) — w = tf je)

Uy, 2 5 2 5 x 5 Gpe

fpf, - ; = = Ye fff

Go = a = 2 =. UY i 2
m nn m . w m 0) : m
n = wn oe z w z= n

LIWS SaluvygdiT_LIBRARIES SMITHSONIAN INSTITUTION NOILNLILSNI_NVINOSHLINS Saluvagiig

, ¥ i

NVINOSHLIWS
SMITHSONIAN
NWINOSH.LIINS
NVINOSHLIWS

NVINOSHLINWS
SS
SMITHSONIAN

SMITHSONIAN

wee

VIAN INSTITUTION NOILOLILSNI_NVINOSHLINS S31YVYEIT LIBRARIES SMITHSONIAN INSTITUTION

I

Z 3 2 ts 2 a We 2
Zw a os w sat ey 7)
dp, ra co = ce z fag Yip, eat
Vise < a - =i ee YS A
“4, & feed ha fae (= we (coms
ai = a a ; <i
3 a ) ise o ea rs)
Zz 4 = - z ay z 4
LINS S3IYVUdIT LIBRARIES SMITHSONIAN INSTITUTION NOILNLILSNI NVINOSHLINS S43! YyVudit
zZ i S = ay Zz ia
) ° e) i s)
E 2 Bite. ; = 5 23 5
ea rae ze = wZ Hue = = > =
= z i Uy » - 2
. 2 ; 2° x E 5 z
NIAN INSTITUTION mi NOILNLILSNI_ NVINOSHLINS S3 lYVvud ae B RAR | ES SMITHSONIAN INSTITUTION

bf pera ie Dard yw a ioe ” re
ES SMITHSONIAN INSTITUTION NOILNLILSNI NVINOSHLINS S31YVYSIT_LIBRARIES SMITHSONIAN IN
2 > x ” z od =
Ww WW Ag wu WwW
\ a 4 AS ne 4 ce. tf 4 a A
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s/ > o = NY o = oc Uy, a \
Cae 3 E : c 5 a “Ge 3
az : z af z ae) z =i Z
INI _NVINOSHLIWS SAIYWVYSI7 LIBRARIES SMITHSONIAN INSTITUTION NOILNLILSNI~NVINOSHLIWS ~S3
Be = i = | = S = 5
o = w = YY, ow 4 w =
\ 2» = Pe = Gly, » = a 5 fz
“| > E > = LCi te vad Ee |S
Ben - 2 — ORE? = 2 =k
m w nw?’ a Ta) m ”
Lop) Hy Ww = (ap) = w =
ES SMITHSONIAN INSTITUTION NOILNLILSNI NVINOSHLIWS Sdluvugit_LIBRARIES SMITHSONIAN INS
n a ce (oz) ud n . i . n” =
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- 2 = ~~ \S Za Ff Co irs 2 = \N SS = a
: zo 5 : = a :
NI_NVINOSHLINS S3IYVYSIT LIBRARIES SMITHSONIAN INSTITUTION NOILALILSNI_NVINOSHLINS Sa
\ = a a eZ Ma. we S AG &
C SS : c = oP Ss c NY 2
= NS" a ca a = Ps 2 ONY" 2
o aN = fe) 2a fe) = fe) “SS -

x = co 2 aa) > ay) as =)
-S_ SMITHSONIAN INSTITUTION NOILNLILSNI NVINOSHLIWS S3INVYUSIT LIBRARIES SMITHSONIAN _ INS
5 2 = ke z eo S =
Wish. az 5 0] = eo) 5 a
: ke : > ia Ps = > ke ys >
ie Z = 2 i 2 mh =
22) n Sam no at 2) =
z o z O z G Zz o
NI_NVINOSHLINS S3IUVYSIT LIBRARIES NOILNLILSN! NVINOSHLINS $3
z 2) = eis ” z= no z o
= = oss SS = < = Pras =
= Sal ES gy = Ss ‘S 4 > = Zz 4
5 ig S or QS iD 0g 2,
g g LY 2X 2 2 z zg ner
= 2 iy = Ng = 2 = ahs
Ss > = > = > = =
wo Fan n” : Pe 7) Fa Yn 2

-S SMITHSONIAN INSTITUTION NOILNLILSNI NVINOSHLINS SJIYVYUGIT LIBRARIES SMITHSONIAN

NS

Lu , Ber, Ww we Ww # 2

= Ui yg > z 4 QE j = at yt
| 5 GS = Ps a We < a <Yytyy F

i fiz = WO oc a GZ

a We 3 z iE: = a UY 3

a ead o Zz . 2 a
NI_NVINOSHLINS _S31NYVYIT_ LIBRARIES SMITHSONIAN” INSTITUTION NOILNLILSNITNVINOSHLINS~ S32
| Sa \ S oad es = z= (rs Ne =

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2 E = = E :
| = 2 > = ass =) =)

Les > Ke . > — > =

cad = = a ae = ce i

B Z Bs z i Z a z
= INSTITUTION NOILNLILSNI_NVINOSHLINS Salyyvygiq LIBRARIES INS

ZZ “% wo =. (ap) : z= ie w >

= 5 \s = Gy, & = z = Z
= 2x3 WE? g E g 2
= E WW" 2. Maa = Zs = 2 Ss

z eae z z ee ne -
H_NVINOSHLINS S3IYVYGIT LIBRARIES SMITHSONIAN INSTITUTION NOILNLILSNI NVINOSH TING 33
@ e é a 2 i zi
3h. = y 2 o us ul

5 \ fag —. fad . =f a aAN\ ao

af <s S 4 (ee .

fe) \ = 5 co. = a x \\ rs

oe = = a mee <=) =

S_ SMITHSONIAN_INSTITUTION NOILNLILSNI NVINOSHLINS S3!1YVYdIT_LIBRARIES SMITHSONIAN INS

Lig

NOILNLILSNI_ NVINOSHLINS S3 |

INSTITUTION NOILNLILSNI

sa1yuvuain

INSTITUTION
INSTITUTION

INSTITUTION
saluvugii
Sa1uvugiy

S-SAleVe ata

SAIYVYAGIT_ LIBRARIES SMITHSONIAN INSTITUTION

\N
VS
N
S

pee