Natural history of economic mollusks of the United States

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[EXTRACTED FRE IM SECTION ONE OF THE FISHERIES AND FISHERY INDUSTRIES
THE UNILED STATES. Pages Plates 250-259

NATURAL HISTORY OF ECONOMIC MOLLUSKS

OF THE

UNITED: STATES.

BY

ERNEST INGERSOLL and JOHN A. RYDER.

WASHINGTON:
GOVERNMENT PRINTING OFFICE.
1893.

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CUTTLES, SNAILS, BIVALVES, ETO.
By Ernest INGERSOLL.

205. THE CUTTLES—CEPHALOPODA.

The mollusks called “ Cuttles” or “‘Cuttle-fishes” bear a very important relation to the fisheries
and consequently to the food supply of the United States. It has recently been ascertained that
some of these Cuttle-fishes attain huge bulk and corresponding abilities for destruction. The two
species of Architeuthis (A. princeps and A. Harvey?), roaming through the North Atlantic and now
and then stranded upon the beaches of Newfoundland, have each a total length of from thirty to
fifty feet, and a weight of solid flesh amounting to thousands of pounds.

“The Cuttles,” says Dr. Philip Carpenter, ‘have very acute senses. They have an approach
to a brain, inclosed in a cartilaginous skull. They can hear sounds, and evidently enjoy the taste
of their food. They have a large, fleshy tongue, armed with recurved prickles, like that of the lion.
They either crawl on their head tail upwards, or swim, tail foremost, by striking with their arms,
or squirt themselves backwards by forcing water forward through their breathing funnels.

“They are ferocious creatures, the tyrants of the lower orders, and do not scruple to attack
and devour even fishes. The larger kinds are deservedly dreaded by man. Their weapons con-
sist in their powerful arms, which are abundantly furnished with rows of cup-like suckers, each
of which fastens on its prey or its foe like a limpet to the rock. Often these are accompanied with
sharp-curved teeth, strong enough to be preserved even in fossil species.”

The giant Cuttle-fishes of the north (Architeuthis) and the commoner Squids and Calamaries of
our Atlantic coast belong to the ten-armed division of the order termed Decapods. The three
smaller species ordinarily met with are Loligo Pealei, Loligo Pealet var. pallida, and Ommastrephes
illecebrosus. On the extreme southern coast they are replaced by an Octopod (Octopus granulatus).

Of these four, Loligo Pealei is the common Squid of Long Island Sound and southward, and
when full grown it is more than a foot in length. The color when living is very changeable, owing
to the alternate contractions of the color-vesicles or spots, but red and brown predominate, so as
to give a general purplish-brewn color. An allied variety or subspecies, named pallida, is a
“pale, translucent, gelatinous-looking” creature, with few spots on the back and nearly white
beneath. Commonly five or six inches long, exclusive of the arms, it frequently grows much larger,
and is of broader and stouter proportions than the type-form, from which it is further distin-
guished by its broader caudal fin and the larger size of its suckers. It belongs especially to the
western end of Long Island Sound, ‘“‘ where it is abundant with the schools of menhaden, on which
it feeds.”

“This species,” writes Verrill,! “is found along the whole coast from South Carolina to Massa-
chusetts Bay.

“Tt is the Common Squid from Cape Hatteras to Cape Cod. In Long Island Sound and Vineyard
Sound it is very abundant, and is taken in large numbers in the fish-pounds and seines, and used
to a large extent for bait. It is comparatively scarce, though not rare, north of Cape Cod. The
young were trawled by us in many localities in Massachusetts Bay in 1878. Large specimens were
taken in the pounds at Provincetown, Massachusetts, August, 1879. It was taken in considerable

5 1 Report U. S. Fish Commission, part vii, 1882, p. 355. ;

687

688 NATURAL HISTORY OF AQUATIC ANIMALS.

quantities, in breeding condition, in the fish-pounds at Cape Ann, near Gloucester, Massachusetts,
May, 1880 (var. borealis). It has not been observed north of Cape Ann. Its southern limit is not
known to me, but it appears to have been found on the coast of South Carolina.

“Tn depth, it has occurred from low-water mark to fifty fathoms. The eggs’ have often been
taken by us in the trawl, m great abundance, at many localities along the southern shores of New
England, in five to twenty-five fathoms.

“Tt is known to be a very important element in the food supply of the bluefish, tautog, sea-
bass, striped bass, weakfish, king-fish, and many other of our larger market fishes.

“Tn the Gulf of Mexico this species appears to be replaced by another species (Loligo Gahi
D’Orbigny). Of this we have several specimens, collected on the west coast of Florida, at Egmont
Key, near Tampa Bay, by Col. E. Jewett and Mr. W. T. Coons. This species is closely allied to
L. Pealei, but has a more slender form, with the caudal fin shorter and narrower in proportion to
the length of the mantle. The pen has a shorter and broader shaft, and a narrower and more
oblong blade, which has parallel, thickened, and darker-colored portions between the midrib and
margins. The tentacular suckers have their horny rings more coarsely and equally toothed, there
being only a partial alternation of larger and smaller teeth.

“ Along our southern coast, from Delaware Bay to Florida, a much shorter and relatively
stouter species (oligo brevis Blainy.) occurs, which might be mistaken by a careless observer for
the present species. In addition to its shorter body, it has very different large, tentacular suckers,
with the teeth on the horny rim coarser and all of similar form and size. Its pen is also shorter
and relatively broader, and different in structure.”

“T am not aware,” he says elsewhere,? “that any definite information has hitherto been
published as to the rate of growth or length of life of any of our cephalopods. By some writers it
has been stated that the Squids are all annual, but this seems to be a mere assumption, without
any evidence for its basis. Therefore I have for several years past preserved large numbers of
specimens of the young of Loligo Pealei, collected at different seasons and localities, in order to
ascertain, if possible, the rate of growth and the size acquired during the first season, at least.
One of the following tables (1) shows some of the data thus obtained.?

“There is considerable difficulty in ascertaining the age of these Squids, owing to the fact that
the spawning season extends through the whole summer, so that the young ones hatched early in
June are as large by September as those that hatch in September are in the following spring.
Owing to the same cause, most of the large lots of young Squids taken mm midsummer include
various sizes, from those just hatched up to those that are two or three inches long. They are
often mixed with some of those of the previous year, considerably larger than the rest. Earlier in
the season (in May and the first part of June), before the first-laid eggs begin to hatch, the
youngest specimens taken (60™™ to 100™™ long) are presumed to belong to the later broods of
the previous autumn, while those somewhat larger are believed to be from earlier broods of the
previous summer, and to represent the growth of one year very nearly.

“Taking these principles as a guide, I have arrived at the following conclusions from the data
collected :

SO Pele young Squids begin to hatch at least as early as the second week in June, on the

1TIn early summer this Squid resorts to gravelly and weedy bottoms : to lay its eggs. They are e contained i in punches
or clusters, sometimes six or eight inches in diameter, consisting of hundreds of gelatinous capsules each holding
numerous eggs. These clusters are attached to some fixed object, and the oysters upon planted beds offer conveniences
which the Squid is very likely to adopt. This occurrence seems to be a source of decided harm in Delaware Bay, for the
oystermen there assert that the larger “‘sea-grapes’’ (as they call the egg-bunches) lift many oysters from the bottom by
their buoyancy and float them off in stormy weather.—E. I.

2 Report U. 8. Fish Commission, part vii, 1882, p pp. 353~355.

3See the original article.

RATE OF GROWTH OF YOUNG SQUIDS. 689

southern coast of New England, and continue to hatch till the middle of September, and perhaps
later.

“2. By the second week in July, the first hatched of the June Squids have grown to the size
in which the body (or mantle) is 30™ to 48™™ long; but these are associated with others that are
younger, of all sizes down to those just hatched. They begin to show a disposition to go in
‘schools’ composed of individuals of somewhat similar sizes.

“3. By the second week in Angust, the largest June Squids have become 50™™ to 68™™ in
length of body, and the later broods are 5™™ to 50" long. As before, with these sizes occur others
of all ages down to those just hatched. It should be observed, however, that in those of our
tabulated lots taken by the trawl the very small sizes are absent, because they pass freely through
the coarse meshes of the net. ;

“4, By the second week in September, the June Squids have the mantle 60™™ to 82™™ long.
All the grades of smaller ones still abound. <A few larger specimens, taken the last of August
and in September, 84™™ to 110™™ long, may belong to the June brood, but they may belong to
those of the previous autumn.

“5. In the first week of November, the larger young Squids taken had acquired a mantle-
length of 79™™ to 85™™, but these are probably not the largest that might be found. Younger
ones, probably hatched in September and October, 8™™ to 20™™ in length of body, occurred in vast
numbers November 1, 1874. The specimens taken November 16, off Chesapeake Bay, having the
mantle 40™™ to 70™ long, probably belong to the schools hatched in the previous summer.

“6. In May and June the smallest Squids taken, and believed to be those hatched in the
previous September or October, have the mantle 62™™ to 100™" long. With these there are others
of larger sizes, up to 152™™ to 188™™, and connected with the smaller ones by intermediate sizes.
All these are believed to belong to the various broods of the previous season. In these the sexual
organs begin to increase in size and the external sexual characters begin to appear. The males
are of somewhat greater length than the females of the same age.

“7, In July, mingled with the young of the season, in some lots, but more often in separate
schools, we take young Squids having the mantle 75™™ to 100™™ long. These we can connect by
intermediate sizes with those of the previous year taken in June. I regard these as somewhat
less than a year old.

‘8. Beyond the first year it becomes very difficult to determine the age with certainty, for those
of the first season begin, even in the autumn, to overlap in their sizes those of the previous year.

“9. It is probable that those specimens which are taken in large quantities, while in breeding
condition, during the latter part of May and in June, having the mantle 175™™ to 225™™ long in
the females and 200™™ to 275™™ long in the males, are two years old.

‘10. It is probable that the largest individuals taken, with the mantle 300™™ to 425™™ long,
are at least three years, and perhaps in some cases four years old. The very large specimens
generally occur only in small schools and are mostly males. The females that occur with these
very large males are often of much smallér size, and may be a year younger than their mates.

“11, When Squids of very different sizes occur together in a school, it generally happens
that the larger ones are engaged in devouring the smaller ones, as the contents of their stomachs
clearly show. Therefore, it is probable that those of a similar age keep together in schools for
mutual safety.

“19. Among the adult specimens of var. pallida taken November 16 and December 7, at
Astoria, there are several young ones, from 75™" to 120™™ in length, with rudimentary repro-
ductive organs. These may, perhaps, be the young of the year, hatched in June.”

44

690 NATURAL HISTORY OF AQUATIC ANIMALS.

Young Squids in inconceivable numbers, and even the adults, are greedily devoured by
bluefish, black bass, striped bass, weakfish, mackerel, cod, and many other marine animals.
Thus they are really of great importance as food for our most valuable market fishes.

North of Cape Cod the Squid is represented by the Sea-arrow or Flying Calamary, Omma-
strephes illecebrosus, sometimes called “short-finned” in contrast to the long “fins” characteristic
of the Loligos, which they resemble in size and color.

Professor Verrill has given the following graphic account of this species:

““When living, this is a very beautiful creature, owing to the brilliancy of its eyes and its bright
and quickly-changing colors. It is also very quick and graceful in its movements. This is the
most common ‘Squid’ north of Cape Cod, and extends as far south as Newport, Rhode Island, and
‘in deep water to the region off Cape Hatteras. It is very abundant in Massachusetts Bay, the
Bay of Fundy, and northward to Newfoundland. It is taken on the coast of Newfoundland in
immense numbers, and used as bait for codfish. It occurs in vast schools when it visits the coast,
but whether it seeks those shores for the purpose of spawning or in search of food is not known.
I have been unable to learn anything personally in regard to its breeding habits, nor have I been
able to ascertain that any one has any information in regard either to the time, manner, or place
of spawning. At Eastport, Maine, I have several times observed them in large numbers in mid-
summer. But at that time they seemed to be wholly engaged in the pursuit of food, following
the schools of herring, which were then in pursuit of shrimp (Thysanopoda norvegica), which occur
in the Bay of Fundy, at times, in great quantities, swimming at the surface. The stomachs of the
Squids taken on these occasions were distended with fragments of Thysanopoda, or with the flesh
of the herring, or with a mixture of the two, but their reproductive organs were not in an active
condition. The same is true of all the specimens that I have taken at other localities in summer.
From the fact that the oviducts are small and simple, and the nidamental glands little developed,
I believe that it will eventually prove that this species discharges its eggs free in the ocean, and
that they will be found floating at the surface, either singly or in gelatinous masses or bands, not
having any complicated capsules to inclose them. Nothing is known as to the length of time
required by this species to attain its full size. It probably lives several years.

“This Squid is an exceedingly active creature, darting with great velocity backward, or in
any other direction, by means of the reaction of the jet of water which is ejected with great force
from the siphon, and which may be directed forward or backward, or to the right or left, by
bending the siphon. Even when confined in a limited space, as in a fish-pond, it is not an easy
matter to capture them with a dip-net, so quick will they dart away to the right and left. When
darting rapidly the lobes of the caudal fin are closely wrapped around the body and the arms are
held tightly together, forming an acute bundle in front, so that the animal, in this condition, is
sharp at both ends, and passes through the water with the least possible resistance. Its caudal
fin is used as an accessory organ of locomotion when it slowly swims about or balances itself for
some time nearly in one position in the water:

“The best observations of the modes of capturing its prey are by Messrs. 8S. I. Smith and Oscar
Harger, who observed it at Provincetown, Massachusetts, among the wharves, in large numbers,
July 28, 1872, engaged in capturing and devouring the young mackerel, which were swimming
about in ‘schools,’ and at that time were about four or five inches long. In attacking the mackerel
they would suddenly dart backward among the fish with the velocity of an arrow, and as suddenly
turn obliquely to the right or left and seize a fish, which was almost instantly killed by a bite in
the back of the neck with their sharp beaks. The bite was always made in the same place, cutting
out a triangular piece of flesh, and was deep enough to penetrate to the spinal cord. The attacks

HABITS OF THE SEA-ARROW. 691

were not always successful, and were sometimes repeated a dozen times before one of these active
and wary fishes could be caught. Sometimes, after making several unsuccessful attempts, one of
the Squids would suddenly drop to the bottom, and, resting upon the sand, would change its color
to that of the sand so perfectly as to be almost invisible. In this position it would wait until the
fishes came back, and when they were swimming close to or over the ambuscade, the Squid, by a
sudden dart, would be pretty sure to secure a fish. Ordinarily, when swimming, they were thickly
spotted with red and brown, but when darting among the mackerel they appeared translucent and
pale. The mackerel, however, seemed to have learned that the shallow water was the safest for
them, and would hug the shore as closely as possible, so that in pursuing them many of the Squids
became stranded and perished by the hundreds, for when they once touch the shore they begin
to pump water from their siphons with great energy, and this usually forces them farther and
farther up the beach. At such times they often discharge their ink in large quantities. The
attacks on the young mackerel were observed mostly at or near high water, for at other times the
mackerel were seldom seen, though the Squids were seen swimming about at all hours, and these
attacks were observed both in the day and evening.

“Tt is probable, from various observations, that this and other species of Squids are mainly
nocturnal in their habits, or at least are much more active in the night than in the day. Those
that are caught in the pounds and weirs mostly enter in the night, evidently while swimming
along the shores in ‘schools.’ They often get aground on the sand-flats at Provincetown,
Massachusetts, in the night. On the islands in the Bay of Fundy, even where there are no flats,
I have often found them in the morning stranded on the beaches in immense numbers, especially
when there is a full moon, and it is thought by many of the fishermen that this is because, like
many other nocturnal animals, they have the habit of turning toward and gazing at a bright
light, and since they swim backwards, they get ashore on the beaches opposite the position of the
moon. This habit is also sometimes taken advantage of by the fishermen, who capture them for
bait for codfish. They go out in dark nights with torches in their boats, and by advancing slowly °
toward a beach drive them ashore. They are taken in large quantities in nets and pounds, and
also by means of ‘jigs’ or groups of hooks, which are moved up and down in the water, and to
which the Squids cling, and are then quickly pulled out of the water. They are also sometimes
caught by fish-hooks, or adhering to the bait used for fishes.

“Their habit of discharging an inky fluid through the siphon, when irritated or alarmed, is
well known. The ink is said to have caustic and irritating properties.

‘This Squid, like the Loligo, is eagerly pursued by the cod and many other voracious fishes,
even when adult. Among its enemies while young are the full-grown mackerel, who thus retaliate
for the massacre of their own young by the Squids. The specimens observed catching young
mackerel were mostly eight to ten inches long, and some of them were still larger.

“‘This species, like the common Zoligo, has the instincts and habits of a cannibal, for small
Squids of its own species form one of the most common articles of its diet. From an adult female
of ordinary size (G, of our tables), caught at Eastport, Maine, I took a great mass of fragments
of small Squids, with which the stomach was greatly distended. These fragments completely
filled a vial having a capacity of four fluid ounces.

“From the rapidity with which the Squids devour the fish that they capture it is evident
that the jaws are the principal organs used, and that the odontophore plays only a subordinate
part in feeding. This is confirmed by the condition of the food ordinarily found in the stomach,
for both the fishes and the shrimp are usually in fragments and shreds of some size, and smaller
creatures, like amphipods, are often found entire, or nearly so; even the vertebrae and other

692 NATURAL HISTORY OF AQUATIC ANIMALS.

bones of herring are often present. On the other hand, in some specimens, the contents of the
stomach are finely divided, as if the odontophore had been used for that purpose.”’

The loss which the fisheries sustain through their voracity, however, is probably equalized by
the food which Cuttle-fishes furnish the carnivorous fishes and various other denizens of the deep.
For example, the sperm whale seems to rely largely upon a diet of big Squids, sinking to the
bottom where they are groping about, to drag them up, or nipping off their large arms as they
swim about near the surface. Dolphins and porpoises also prey upon the Cuttles, and all the
flesh-eating fishes pursue and devour them at every opportunity, particularly the cod and bluefish.

Knowledge of this fact long ago led to the Squid being taken by fishermen as an attractive
bait. More than half of all the Bank fishing is said to be with such bait. When the shoals of
this mollusk [Zoligo Squid] approach the coast hundreds of vessels are ready to capture them,
forming an extensive cuttle fishery, engaging five hundred sail of French, English, and American
ships. Their habit of moon-gazing, also, is sometimes taken advantage of on the coast of Maine
by the fishermen, who capture them for bait for codfish; they go out in dark nights with torches
in their boats and by advancing slowly toward a beach drive them ashore. Violent storms heap
great windrows of dead Squids on the beach, where they are gathered up, and they are also
sometimes taken on lines adhering to the bait set for fishes. These ‘‘drives” and accidents
happen in the spring, when Cuttles are flocking into shallow water to lay their eggs.

Since this solidly-fleshed animal is so extensively eaten by other animals it is not surprising
to find that men also should number it among the edible products of the sea. ‘The flesh of the
large cephalopodous animals,” says Simmonds,’ ‘was esteemed as a delicacy by the ancients.
Most of the Eastern nations, and those of the Polynesian Islands, partake of it and relish it as
food. They are exposed for sale dried in the bazaars or markets throughout India, and
dried Cuttle-fish may be seen among the articles of Chinese, Japanese, and Siamese food. In
Chili the flesh is also considered a delicacy, and in Barbados the bastard Cuttle-fish or ‘Calmar’
(Loligo sagittata Lam.) is used as an article of food by the lower classes.”

In the Mediterranean also, particularly near Tunis, and along the Portugal coast, the catch
and consumption of Cuttles is large, antounting to nearly a million pounds a year, most of which
is sold in Greece, after being salted and dried or pickled. These are Octopods. ‘The same sort of
Cuttle-fish (Octopus punctatus) serves the double purpose on the Pacific coast, from California to
Alaska, of bait for the fisheries and food for the Indians. For the latter purpose it is chiefly
sought in Puget Sound, where the coast tribes hunt and kill Octopods often large enough to be
dangerous foes in a quarrel, by going to their haunts in canoes and spearing them. To some small
tribes the Octopus affords the chief supply of animal food. There is no reason why squid-fesh
from the northern Atlantic Ocean should not become available as food, and prove desirable—to
those who like it. It would be both wholesome and cheap; and a single Architeuthis would
furnish a meal for a frigate’s crew. In Bermuda the Octopus granulatus regularly forms a portion
of the fare of the fisher families. As the Bermudan fish and methods of capture prevail across
among the Florida reefs, no doubt this habit prevails there also. In New York City there is a
considerable sale of fresh Squids to foreign residents, and the trade is increasing. There seems
no reason why on some coasts this flesh should not be far more thoroughly utilized than it
is at present. i

In addition to its value as a bait, or as a source of oil (our Ommastrephes has been thus
utilized somewhat), and as possible food, the cephalopods contribute two or three useful articles

'Report U. 8. Fish Commission, part vii, 1882, pp. 305-308.
? Commercial Products of the Sea, p. 116.

THE SEA-SNAILS. 695

to commerce. A large portion of them carry under the skin of the back a long, flat, calcareous
“bone” or plate, which serves as a stay or support to the frame in lieu of a skeleton. In some
species it is long and slender like a quill-pen. This bone, reduced to powder, forms a useful
pounce, ‘used in rewriting over erasures to prevent blotting, and in medicine as an antacid.” It
is also combined into a dentifrice. The principal use for it, nevertheless, is for feeding to caged
birds requiring lime for their health. For this purpose several hundred-weight of “ cuttle-bone”
ave brought into the United States annually. It is furnished chiefly from Chinese waters,
but is also collected floating in the Mediterranean. None of our American species afford a useful
cuttle-bone, however; so that this import can scarcely be diminished. The name “Calamary”
is often applied to a Cuttle-fish, and arises from the fact that each of them carries in an internal
gland a supply of blue-black, ink-like liquid, which upon the slightest alarm he discharges into
the water, making a dense cloud under cover of which he rapidly retreats.'. This ink, removed and
dried into little cakes, with a greater or less adulteration, forms the sepia of painters and the
India ink of draughtsmen. Now it is brought almost wholly from Oriental ports, via London,
but it might probably be saved on our coast as well. Provided with pen and ink on all occa-
sions, these mollusks seem truly to stand at the head of the class of animals they represent—
not wholly because of their superior size and loftier brain and organization, but also on the score
of literary accomplishments.

206. THE SEA-SNAILS—GASTEROPODA.

The Gasteropod mollusks, bearing a shell in a single piece and usually spirally whorled, are
not of much direct utility to man, as a rule, on this side of the world, north of the tropics; but there
are a few species which deserve mention. Their principal claim to notice in {lis connection lies
in the fact that they figure upon the habitual bill of fare of various fishes. No doubt the list
appended might be greatly enlarged if we were better informed. particularly in respect to the
southern coast. Thus far the chief knowledge possessed in respect to the mulluscan food of
American fishes is derived from Gould’s ‘‘ Report upon the Invertebrates of Massachusetts,” and
Prof. A. E. Verrill’s report to the United States Fish Commission. From this and other sources
is compiled the succeeding catalogue of species of Gasteropod mollusks that are fed upon by
fishes; these, it must be observed, are confined to the Atlantic coast, and, to a great extent, to the
waters of New England, through lack of information in respect to the similar food of the fishes of
the southern and the western coast. The list includes about fifty species, and reads:

Bela turricula, Bela harpularia, Bela pyramidalis, Bela decussata, Admeté Couthouyé, Neptunea
despecta, Buccinum undatum, Buccinum ciliatum, Tritia trivittata, LIlyanassa obsoleta, Trophon
clathratus, Trophon clathratus var. scalariformis, Purpura lapillus, Astyris rosacea, Astyris lunata.
Natica clausa, Innatia heros, Lunatia grenlandica, Lunatia immaculata, Amauropsis islandica,
Velutina zonata, Velutina levigata, Lamellaria perspicua, Littorina—several species, Triforis nigro-
cinctus, Bittium nigrum, Turritella erosa, Trichotropis borealis, Crepidula fornicata, Crepidula plana,
Aporrhais occidentalis, Scalaria grenlandica, Scalaria Novanglice, Margarita cinerea, Margarita
grenlandica, Margarita argentata, Macheroplax obscura, Puncturella noachina, Tonicella marmora,
Trachydermon albus, Trachydermon ruber, Chiton—various species, Auricula vestita var. Emersonit,

1There are frightful tales abroad of the ferocity with which the larger of these creatures will attack man, and they
are greatly dreaded by the shell-divers of the South Seas; but the truth is the Cuttle-fish is timid, and will hide or run
away whenever he can from anything so large and strange as a man; that is, any Cuttles smaller than the giants of
Newicundland. A diver who touched a large Octopus would instinctively be seized, of course, since the creature would
know no different course of action; but voluntary attack is not credited by those who know most about the habits of the
animal,

694 NATURAL HISTORY OF AQUATIC ANIMALS.

Odostomia striatula, Philine lineolata, Amphisphyra hiemalis, Amphisphyra debilis, Diaphana Gouldii,
and Cylichna alba among salt-water forms; with many species of Melampus, Paludina, Planorbis,
Limnea, Physa, and other fresh-water genera.

But many of these species, and several not mentioned here, have additional claims to our
notice. For example, Buccinum wndatum, the Cape Ann “ Periwinkle,” might well serve as food,
since in Europe it has long been thus utilized. In all the coast towns of England and Scotland
this shell is peddled for food, under the name “ Whelk” or “Wilk,” and it may be bought at all
the street-corners in the poorer quarters of London, where it is esteemed a great luxury. Our
Whelk might equally well be eaten, and is very common northward from Cape Cod to the arctic
regions, living chiefly on rocky shores, but also inhabiting muddy bottoms. It is thus accessible
to castaways upon bleak arctic coasts where no other edible shell-fish of consequence occurs, and
ought not to be forgotten by those who take the risk of shipwreck in Labrador or Greenland.

‘Next demanding attention are two of the largest mollusks on the Atlantic coast north of the
tropies—Fulgur carica and Sycotypus canaliculata. North of New Jersey these two are confused
under the general names of ‘ Periwinkle,” “* Winkle,” and “‘ Wrinkle.” The former of these species
extends “northward only to Cape Cod,” and is uncommon beyond Long Island, while the second
is of more frequent occurrence in Vineyard Sound and along the Connecticut shore than south-
ward. Both are carnivorous, and find in the Oysters a quiet, easy prey; they consequently do
great damage to the beds, and are properly destroyed by fishermen whenever a chance occurs. I
believe this is especially true of the Sycotypus. On the coast of New Jersey and southward,
where the Fulgur reaches an immense size, and is known as the ‘“‘Conch,” the oystermen complain
very little of it.

The Sycotypus is more common north of New York, though it does not exist at all beyond
Cape Cod; while along the coast of New Jersey and southward it is the Fulgur which is charge-
able with nearly all mischief perpetrated, since the other species is rarely seen. Occasionally, as
Verrill mentions, specimens of both may be found crawling on sandy flats or in the ‘tide-pools,
especially during the spawning season, but they do not ordinarily live in such situations, but im
deeper water, on hard bottoms off shore. It is needless to say that they do not burrow at all,
though they are able to insert the posterior part of the foot into the sand sufficiently to afford
them a strong anchorage against currents. A very soft or a very rocky bottoin they equally
avoid.

The curious egg-cases of these mollusks, to which the names ‘‘sea-ruffle” and “ sea-necklace”
are often given by fishermen, always attract the attention of visitors to the sea side, who find
them cast upon the beaches; and we can well echo the pious exclamation of the old historian of
Martha’s Vineyard,—The Author of nature makes a wonderful and copious provision for the
propagation of this worm!” The eggs are discharged in a series of disk-shaped, subcireular, or
reniform, yellowish capsules, parchment-like in texture, united by one edge to a stout stem of the
same kind of material often a foot and a half or two feet in length. “The largest capsules, about
an inch in diameter, are in the middle, the size decreasing toward each end. On the outer border
is a small circular or oval spot, of thinner material, which the young ones break through when
they are ready to leave the capsules, each of which, when perfect, contains twenty to thirty or
more eggs or young shells, according to the season.” Verrill adds interesting particulars, as
follows:

“Dr. Elliott Coues, who has observed Fulgur carica torming its cases at Fort Macon, North
Carolina, states that the females bury themselves a few inches below the surface of the sand on
the flats that are uncovered at low water, and remain stationary during the process. The string

REPRODUCTION OF THE CONCH. 695

of capsules is gradually thrust upward as fast as formed, and finally protrudes from the surface of
the sand, and, when completed, lies exposed on its surface. The string begins as ‘a single shred,
two or three inches long, without well-formed cases; the first cases are small and imperfect in
shape, but they rapidly increase in size and soon become perfect, the largest being in the middle;
the series ends more abruptly than it began, with a few smaller and less perfect capsules. The
number of capsules varies considerably, but there are usually seventy-five to one hundred or
more. At Fort Macon Dr. Coues observed this species spawning in May, but at New Haven they
Spawn as early as March and April. It is probable that the period of spawning extends over
several months. Mr. Sanderson Smith thinks that they also spawn in autumn on Long Island. It
is not known how long a time each female requires for the formation of her string of capsules.
There are two forms of these capsules, about equally abundant in this region. In one the sides of
the capsules are nearly smooth, but the edge is thick or truncate along most of the circumference,
and crossed by numerous sharp transverse ridges or partitions, dividing it into facets. Dr.
Coues states that these belong to Fulgur carica. An examination of the young shells, ready
to leave the capsules, confirms this. The other kind has larger and thinner capsules, with a thin,
sharp outer edge, while the sides have radiating ridges or raised lines. Sometimes the sides
are unlike, one being smooth and more or less concave, the other convex and crossed by ten
or twelve radiating, elevated ridges extending to the edge. This kind was attributed to Fulgur
carica by Dr. G. H. Perkins, and formerly by Mr. Sanderson Smith, but a more careful examina-
tion of the young shells, within the capsules, shows that they belong to Sycotypus canaliculata.”'

Eggs so exposed are subject to numberless accidents, being drifted ashore, ground to pieces
by storms, and no doubt eaten by bottom-feeding fishes, so that only a few eggs out of the
hundreds in each ‘‘necklace” are ever born, or, accomplishing that, are able to survive the perils
of unprotected youth and grow to adult age and strength. Having once done so, however, this
mollusk probably lives to a very great age.

An examination of a specimen of either of these species will show that in both the
muscular part is large and strong and the mouth powerful. The food of the Conch being mainly
the flesh of other mollusks, its method of killing them is one of brute strength, since it is unpro-
vided with the silicious, file-like tongue by means of which the small ‘“ Drills” set at naught the
shelly armor of their victims. The Conch is a greater savage than that. Seizing upon the unfor-
tunate Oyster, unable to run away, he envelops its shell in the concave under surface of his foot,
and, by just such a muscular action as you would employ in grasping an object in the palm of
your fist, crushes the shell into fragments and feasts at leisure on the flesh thus exposed. Where
Oysters or other prey are abundant, this operation is quickly repeated and vastly destructive.
One planter in the upper part of Buzzard’s Bay, where these pests are very troublesome, thought
one Winkle was capable of killing a bushel of Oysters in a single hour. They do not confine
themselves to Oysters altogether, of course; any mollusks or other marine animal, sluggish and
weak enough to be caught and broken up, suffers from their predacity. I was told in New
Jersey, by an intelligent man, that the Conch would even draw the Razor-shell out of his burrow
and devour it. If this be true, no doubt the Soft Clam also falls a victim to the same maraudeyr.
The Quahaug is generally safe in his massive shells.

The oyster-beds most subject to attack and harm by the Winkles and Conchs are those
planted in water which is quite salt, as is the practice in New England and Long Island Sound.
The beds of the Great South Bay, Staten Island, and the southern Jersey coast are well protected
by the outer beaches from the sea, and to these barriers owe their immunity from the Fulgur,
while the Sycotypus, though present inside the beaches, seems to do small damage. Oystermen

‘Report U. S. Fish Commission, part i, 1873, pp. 355, 356.

696 NATURAL HISTORY OF AQUATIC ANIMALS.

will tell you, also, that beds which are disturbed from time to time by the planter will suffer more
harm than neglected beds, especially in summer. Of course it is to be expected, as reported, that
where planting has gone on for many years, there these predatory mollusks have visibly increased
in numbers.

In regard to ridding our beds of this pest, I can only advise, as heretofore, that every effort
be made to destroy every specimen taken and every “necklace” of eggs which can be got hold of.
The trawl, tangles, etc., recommended for the suppression of star-fishes, in my Report to the
Census Bureau upon the Oyster Industries, would take up these eggs at the same time, and thus
do double service. Persistent fighting is the only resource against this enemy, however, as in
the case of others.

Some points of minor interest may be mentioned before leaving this subject. Both of these
shells were used by the Indians of the coast ceremonially, and as material for the making of white
wampum, their money of inferior value, which consisted of bead-shaped sections of the central
column of the shell. From them, also, were fashioned sundry articles of service and ornament,
such as trowels, spoons, and dippers; they are sometimes even yet called “ladle shells.” The
Indians ate the animals, too, when hard pressed for food, and have been followed in this practice
by the whites, to some extent. De Voe says they used sometimes be sent into Catharine Market,
New York, from Long Island, and found sale; “but,” he adds, “they are not generally relished.
being somewhat strong flavored. They are mostly used by the poor who live near the coast.”
Several foreign mollusks, not greatly different, are eaten—generally being boiled—and perhaps
proper cooking would make these Conchs more palatable than they have hitherto proved.

Under the name of ‘ Drill” is included a numerous class of univalve mollusks, which are
carnivorous in their tastes, and armed with a tongue-ribbon so shaped and so well supplied with
flinty teeth that by means of it they can file a round hole through an enemy’s shell,—a habit —
which renders them of much account in the fisheries, where the victim they attack is the valuable
Oyster, as they are sadly prone todo. The mode in which the entrance is made has been clearly
described by Rey. Samuel Lockwood, as follows:

“The tongue is set with three rows of teeth like a file; it is, in fact, a tongue-file, or dental
band, and is called by conchologists the lingual ribbon. . . . Having with the utmost care
witnessed a number of times the creature in the burglarious act, I give the following as my view
of the case: With its fleshy disk, called the foot, it secures by adhesion a firm hold on the upper
part of the Oyster’s shell. The dental ribbon is next brought to a curve, and one point of this
curve, on its convex side, is brought to bear directly on the desired spot. At this point the teeth
are set perpendicularly, and the cur ve, resting at this point, as on a drill, is made to rotate one
circle, or nearly so, when the rotation is reversed; and so the movements are alternated, until,
after long and patient labor, a perforation is accomplished. This alternating movement, I think,
must act favorably on the teeth, tending to keep them suarp. To understand the precise movement,
let the reader crook his forefinger, and, inserting the knuckle in the palm of the opposite hand,
give to it, by the action of the wrist, the sort of rotation described. The hole thus effected by
the drill is hardly so much as a line in diameter. It is very neatly countersunk. The hole
finished, the little burglar inserts its siphon or sucking-tube, and thus feeds upon the occupant of
the house into which it has effected a forced entrance. To a mechanic’s eye there is something
positively beautiful in the symmetry of the bore thus effected—it is so ‘true’; he could not do it
better himself, even with his superior tools and intelligence.”

These small “Snails,” “ Drills,” “Borers,” and ‘Snail-bores,” as they are variously called,
belong to several species of Natica, Purpura, Anachis, Astyris, Tritia, Ilyanassa, ete.; but the master

DESTRUCTIVENESS OF THE COMMON DRILL. 697

and most destructive, as well as most abundant of them all, is the Urosalpinx cinerea of Stimpson.
It is this which is the common ‘ Drill” of the oyster-beds; and it is its eggs, laid in small vase-
shaped capsules, which are often found attached in groups to the under surfaces of stones.
Several of the small mollusks mentioned above lay eggs in this way, but the Drill’s capsules have
very short stalks, or are almost sessile, and are compressed with an ovate outline, while angular
ridges pass down their sides. The natural home of the Drill is the tide-pools and weedy borders
of rocky shallows, where barnacles, hydroids, anemones, rock-loving limpets, and other associated
forms that find shelter among the algw afford it abundant food. Though this is precisely where
the Mussels grow till the rocks are almost black with them, it is said that they are never attacked
by the Drills.

The Urosalpinx sometimes strays to the oyster-beds, but is usually carried there with the seed
supplies, and, finding plenty of nourishment, lives and increases. Though its multiplication is not
very rapid, it is fast enough to make it a very serious obstacle to success in the course of a few
years. In nearly every case I was told that formerly there were no Drills, but now the oyster-
beds were overrun. This was reported in particular of the Great South Bay of Long Island and
at Keyport, New Jersey. I heard less of its ravages in New Jersey, except in the Delaware; but
in Chesapeake Bay nearly every dredge-haul in any part of Maryland or Virginia waters brings
them up. The Potomac seems to be the district least infested. Of course, in such natural haunts
as the rocky shores of Buzzard’s Bay and Connecticut they would be present if there were no
Oysters, and are all the harder to dislodge.

Once having attacked an oyster-bed, they work with rapidity, and seem to make sudden and
combined attacks at considerable intervals. Their disappearance from certain restricted localities,
too, for a long time is unexplained.

What is the best way to combat them, or whether there is any hope of ridding the beds of
them, are questions often discussed by oyster-culturists. It is certain that a great deal of trouble
might be avoided if care were exercised in culling seed to throw out—not into the water, but on
the ground or deck—all the Drills, instead of carrying them to one’s beds, deliberately planting
them, and then grumbling at destruction which previous care would have avoided. It would cost
less in point of mere labor, no doubt, to prevent this plague than to cure it when it became no longer
endurable. Some planters clean up pieces of bottom very thoroughly before planting, in order to
get all this sort of vermin out of their way, as well as to stir up the mud and fit it for the reception
of spat. It is on hard bottom that Drills are especially troublesome, and here some planters go
over the ground with a fine-meshed dredge in order to get them up, but they fail to catch all.
This is done at Norwalk, Connecticut, I know, and the men who have steamers find in the celerity
with which they are able to accomplish this sort of work a great argument against any restriction
to exclusively sailing-rig.

The Drill can be exterminated to a great extent, also, by diligently destroying its eggs. Small
boys might well be paid to search for them and destroy them among the weedy rocks by the shore
ati low tide. A gentleman at Sayville, Long Island, assured me that in those years when eels
were plentiful the Drills were kept down because the eels fed on their eggs. This gentleman said
in the Great South Bay the Drills were nearly conquering the planters, and he advised the
removal of all shells from the bottom of the bay, in order that the Drills might have nothing left
on which to place their eggs. This might do there, where there are no rocks along the shore and
the Drill is not native; but I doubt whether so sweeping a measure of protection could ever be
carried out.

On the Pacific coast Gastrochena and various pholadiform mollusks are a great bane to the

698 NATURAL HISTORY OF AQUATIC ANIMALS.

oyster-beds, but they penetrate by digging burrows wherein their whole shell is lodged. Where
large numbers of these are present, with the help of boring-worms and sponges, they may so
riddle a reef as to cause its entire disintegration under the first gale. A fourth borer is Purpura
lapillus, which is of interest in another direction. The famous Tyrian purple of ancient days—
the regal dye that was deemed too splendid a color to be worn by any but kings and nobles—
was produced from a sea-snail, and conchologists have busied themselves to discover which
particular one.

In the works of Pliny and Aristotle, the earliest sources of knowledge on the subject, the
information is too vague to be relied upon. Dr. Roth, of Munich, in a paper read before the Jeru-
salem Literary Society, says that several years ago (previous to 1857) he found at Jaffa the
Purpura patula, sought as food by the Christians during fast days: ‘“‘On puncturing this animal
there issued a greenish liquid, which, when exposed to the sunshine, changed to purple. This
purple increased in brilliancy when it was washed.” Comparing this with the accounts left by the
ancients, Dr. Roth thinks the color he produced is evidently their blue color, for they had a blue-
purple, a deep purple, and a red-purple. ‘Between Soor and Saida,” according to the same
author, “the Murea truncatus, or trunculus, is found in abundance, and its color is more brilliant
than that of the Purpura. One of these Murex is sufficient to dye a square inch of cloth, which
would require five individuals of Purpura patula. Wool takes the dye better than any other
substance; silk takes it with difficulty.”!

Linton, in his work “ On Ancient and Modern Colours,” as quoted by Simmonds (‘‘ Commer-
cial Products of the Sea,” p. 304), states that the Purpure of the best description were chiefly found
on the rocks of Tyre, on the coast of Asia. They were also collected at Mininge, on the Gretulan
shore in Africa, and on the coast of Laconia in Europe. The colors varied according to the
locality in which they were taken, and also according to the animal’s haunt, as has since been
proved by zoologists. Thus, when it lived among sea-weeds or mud the juice 1t contained was
comparatively worthless; when among pebbles its quality was improved; and the dye was best
when the food and surroundings were varied. Researches carried still further proved that to
produce the richest and most costly dye which art could exhibit, the liquid must be used in
conjunction with that procured from other shell-fish. Just what the species were that were used
it is now impossible to tell, but they were allied to Murex and Buccinum. Niter, urine, water, salt,
and certain sea-weeds were also mixed with the Purpura liquor in compounding certain tints. ‘ In
the reign of Augustus,” says Simmonds. ‘one pound of wool dyed with the Tyrian purple sold for
about £36 sterling [about $175]. We need not wonder at this enormous price when the tedious
nature of the process is considered, and the small quantity of dye obtained from each mollusk.
For fifty pounds of wool the ancients used no less than two hundred pounds of the liquor of the
Murex and one hundred pounds of that of the Purpura, being six pounds of liquor to one of wool ;
consequently the rich Tyrian purple fabrics vied in value even with gold.”

The liquor was procured by placing the small shells in a mortar and crushing them. Animals
extracted from the larger shells were added, and also urine, pure water, or water in which purple
Snails had been allowed to putrefy. In this mixture the cloth was soaked and afterwards exposed
to the light, sometimes under the influence of warmth to accelerate the process.

Tt is said that the dyeing property is a transformation of urie acid into purpurate of ammonia,
called murexide. This is a splendid substance when pure, presenting in one direction beautiful
metallic green reflections, and in others brown and purple tints. Some chemists assert that it is

1 Purpson: Utilization of Minute Life. London Groombridge & Sons, 1864, p. 144,

SHELLS USED FOR CAMEO-CUTTING. 699

to this substance that the iridescent plumes of humming-birds, pheasants, and peacocks owe their
wonderful brilliancy. Murexide is now obtained not only from mollusks, but from guano, ete.

Dyes from mollusks have been obtained in all ages and almost all quarters of the world, and
not only our Purpura lapillus, but also another species which we share with Great Britain, the
Whelk (Buccinwm undatum), have been the subject of successful experiments of this sort. “ If the
shell of Purpura lapillus is broken, there is seen on the back of the animal, under the skin, a
slender, longitudinal, whitish vein, containing a yellowish liquor. When this juice is applied to
linen, by means of a small brush, and exposed to the sun, it becomes green, blue, and purple, and
at last settles into a fine unchangeable crimson.” The housewives of New England therefore have
growing abundantly on their sea-side rocks little living bottles of indelible ink which cannot be
excelled by any manufactured product for either beauty or durability, since neither acid nor alkali
will affect its color.

On the Pacific coast occur shells of the genus Olivella, so called because they resemble small
olives. There are three species, Olivella biplicata, O. gracilis, and O. dama. The first named of
these shells certainly, and possibly the other two, now and then were made into money by many
Californian tribes of Indians, which money circulated widely on the Pacific slope. The common
Indian name for this Olivella money was “coleol.” It was made by grinding off the apex or spire
of the shells in such a way that they could be strung. They are still used by some tribes in the
form of double necklaces as ornaments, but are regarded as of small value. Sometimes the shell
was broken crosswise and ground into little disks which passed as coins. This money was very
ancient and widespread through aboriginal traffic in connection with other forms of shell-money to be
mentioned hereafter, and which the present writer has fully discussed in a paper on ‘‘ Wampum”
contained in the American Naturalist,! to which the reader is referred.

Cameos are articles of ornament made by carving portions of various shells in such a way that
a raised figure of one color shall be relieved against a ground of another tint constituting the under
layer of the shell. These colors may vary—white on an orange ground, or on dark claret; pale
salmon-color on orange; yellow on pink, etc. Anciently cameos were cut upon gems with immense
labor, but latterly this easier imitation in shell has almost entirely superseded the intaglios in
onyx, agate, and jasper. The cameo artists live mostly in London and Paris, and use several
species of large shells that combine a white crust with a nacreous understratum of a different tint.
Two only of these shells come from American waters, and these only touch our coast in tropical
Florida—Cassis madagascariensis and Strombus gigas—the ‘‘ Helmet-shell” and the ‘“‘Conch.”

Of the Helmet-shell several sorts are used in cameo-cutting. Our American example (which
got its name, madagascariensis, through an error in regard to the locality of the type-specimen)
has a blackish inner coat, called an “onyx” ground, and shows up white on a dark claret-color.
It is known to the trade as the Black Helmet, and is highly esteemed by cameo-cutters.

The Conch or Queen Conch (Strombus gigas) is of less account in cameo-making, because it
affords a less quantity of surface suitable for the work—a portion of its broad, rose-tinted lip.
Various other ornaments are often made from this and other large shells by turning and sawing
with special machinery, and thus a large demand is created, which is satisfied chiefly through
brokers in London and Liverpool. Just how many shells are sent to England annually it is
impossible to tell; but the amount reaches some tens of thousands. There is also a large
commerce in them both to Europe and to the United States to be used as ornaments alone, and to
be given away by grocers and tea-dealers to promote their custom. In the West Indies, and on

1 American Naturalist, xvii, May, 1883, pp. 467-479.

700 NATURAL HISTORY OF AQUATIC ANIMALS.

many plantations in the Gulf States, the Conch is perforated at the apex of the spire, and forms
a horn, used to eall workmen in from the fields and at dinner. From fragments of this great
mollusk, also, the Indians of Florida and the Antilles made their most esteemed beads and
pendants. Cabeza de Vaca says that the columella of large Conchs were chiefly available for this
purpose. ‘These beads are more or less cylindrical or globular, and always drilled lengthwise.
Some are tapering at both ends, resembling a cigar in shape, and were two and one-half inches in
length. The aborigines also made . . . peculiar pin-shaped articles consisting of a more or
less massive stem which terminates in a round knob.”

The Strombus enters, when ground, into the manufacture of porcelain; is extensively burned
for lime; and is carefully calcined for medicinal purposes. There is also derived from it a
secondary product of great value—the conch-pearl. When perfect, this pearl is described as either
round or egg-shaped and somewhat larger than a pea, of a beautiful rose-color, and watered, that
is, presenting, when held to the light, the sheeny, wavy appearance of watered silk. It is
however, very rare to find a pearl which possesses all the requirements that constitute a perfect
gem, and such proves an exceedingly valuable prize. Although many of these pearls are annually
obtained by the fishermen in the Bahamas, not more than one in twenty proves to be a really
good gem. Pink is the most common and only desirable color, although white, yellow, and brown
pearls are occasionally found. Even among the pink ones there is usually some defect which mars
their beauty and materially injures them; some are very irregular in shape and covered apparently
with knobs or protuberances; others are too small, while many lack the watering which gives
them their great value and chief beauty. Most of the conch-pearls have been sent to London,
and the demand for them is increasing; a few come to New York.

Lunatia heros is very conspicuous along our coast, from the Gulf of Saint Lawrence to Cape
Hatteras or beyond, wherever sandy shores and pure waters are to be found, and it is abundant
and of very large size on the outer beaches of the coast of New Jersey. ‘‘When in motion the
white soft parts are protruded from the shell to a remarkable extent and spread out broadly on
all sides, so as nearly to conceal the shell; the foot is large, flat, and broadly expanded, with thin
edges, and by means of it the animal is able to burrow, like a mole, beneath the surface of the
sand.” This Snail, like many others of its tribe, drills round holes through the sides of various
bivalve shells by means of the small flinty teeth on its ribbon-like tongue, which acts like a rasp,
and having thus made an opening it inserts its proboscis and sucks out the contents. All sorts of
burrowing bivalves in this way fall victims to this and its close ally, the Neverita duplicata. ‘Nor
do they confine themselves to bivalves, but will drill any unfortunate Gasteropods they may happen
to meet, not even sparing their own young.” Their usual haunts are away from the oyster-beds,
however, so that, although they are a familiar sight in the dredge, the harm they do to this
industry is of small account.

Following this in the list come various small shells, such as those of the genera Littorina,
Rissoa, Melampus, and Bittium, of which it can only be said that they serve a very useful purpose as
Scavengers, Swarming upon the mud exposed at low tide and greedily devouring carrion of fishes,
ete., which would otherwise decay and pollute both air and water. The same good service is done
by the small moilusks previously noticed as “Borers,” and many following.

This brings us to the beautiful family of Abalones, Ormer-shells, or Sea-ears, in whieh there is
a very large trade on the Pacific coast, under the industry of the Chinese there, to which will be
given a special chapter.

In the Limpets (Crepidula and Aemea) the oystermen consider they have a friend, since when
they see these clustering upon their planted beds they look forward to a profitable harvest the

THE EDIBLE LAND SNAILS. 701

coming autumn. A Californian species (Fissurella aculeata) was used as money by some of the
native red men of the coast.

In respect to the odd pill-bug-like shells of the several species of Chiton of our eastern
shore I can say nothing; but in Bermuda a larger Chiton is gathered for soup, and the broth is
said to be very good. The Bermudans also make use of that Chiton as a bait with which to take
the large lobsters of the island, themselves intended to act as bait for fishes.

The sea surrounding Bermuda is of great transparency, and the fishermen can readily discern
the long horns of the lobster protruding from his hiding place among the rocks, at a considerable
depth. The only plan by which they can get him, however, is to entice him out of his refuge.
To do this they mat together a quantity of Chitons until they have formed a ball several inches in
diameter. To this they attach a string, and—having previously baited the bottom in front of the
lobster’s den and left him to enjoy it until his confidence was ecaptured—let the ball dangle before
his nose. Thinking this only a larger tidbit, he seizes it, and, to his amazement, is swiftly drawn
up to daylight and torn to pieces to form a lure for equally unwary fishes.

“These shells have been called by different names, all, however, indicative of their form, such
as ‘ Wood-louse,’ ‘ Sea-boat, ‘ Rattle-snake’s Tail,’ ‘Lobster’s Tail, ‘Sea-bug,’ and ‘ Sea-caterpillar.’
The French say that the animal may be eaten, and we are told that the Iceland fishers swallow it
raw to quench thirst, and pretend that it is good, also, against sea-sickness.” The American
Indians of the Northwest coast, South Sea Islanders, and other savages find the Chiton acceptable
as food.

In Melamprus bidentatus we have a small shell which swarms upon the mud and among the
eel-grass, affording food to many fishes and acting as a scavenger of the marshes. In addition to
this, it has a place in these remarks because it belongs to the division of air-breathing mollusks,
and introduces not only the fresh-water shells Limnea, Physa, Planorbis, ete.. that feed the inland
fishes, but also the edible land Snails. To these latter-interesting mollusks I lately devoted a
chapter in my ‘“ Friends Worth Knowing,”! from which I quote whatever applies to the present
purpose:

“Snails, being great eaters, meet their just reward in being eaten. The paludine forms are
sought after by all sorts of water birds, particularly ducks and rails; while the thrushes and
other birds crush the shells of the land Snails and extract their juicy bodies. The woodland
birds, however, will not eat the naked-bodied Slugs: the slime sticks to their beaks and soils their
feathers; but the ducks seem to have no such dainty prejudices. Some mammals, like the
raccoons and wood-rats, also eat them; insects suck their juices, and the carnivorous Slugs prey
upon one another. Lastly, man, the greatest enemy of the brute creation, employs several species
of Snails for culinary purposes. By the Romans they were esteemed a great luxury, and portions
of plantations were set apart for the cultivation of the large, edible Helix pomatia, where they
were fattened by the thousand upon bran soddenin wine. From Italy this taste spread throughout
the Old World, and colonies of this exotic species, survivors of classical ‘ preserves,’ are yet found
in Great Britain where he Roman encampments were. They are still regarded as a delicacy
in Italy and France, the favorite method of preparation being to boil in milk, with plenteous
Seasoning. Frank Buckland says that several of the larger English species are excellent food for
hungry people, and recommends them either boiled in milk, or, in winter, raw, after soaking for
an hour in salt and water. Some of the French restaurants in London have them placed regularly
upon their bills of fare. Thousands are collected annually and sent to London as food for
cage-birds. Dr. Edward Gray stated, a few years ago, that immense quantities were shipped

1 Harper and Brothers, New York, 1880.

702 NATURAL HISTORY OF AQUATIC ANIMALS.

alive to the United States ‘as delicacies’; but I am inclined to consider this an exaggeration
growing out of the fact that, among our fancy groceries, ‘a few jars of pickled Snails, imported
from Italy, figure as a curiosity, rather than something needed for the table. The same author
records that the glassmen at Newcastle once a year have a snail feast, collecting the animals
in the fields and hedges on the Sunday before.

“Mr. W. G. Binney, for whom a sirup of Snails was prescribed by two regular physicians in
Paris in 1863, points out how old is the belief that land mollusks possess valuable medicinal
qualities. In the Middle Ages the rudimentary shell of the Slug acquired a high rank among the
numerous bezoars and amulets which were supposed to protect the body from evil influences, and
to impart health and activity. The accounts of these virtues, copied from one author to another,
have perpetuated the early superstitions until it is difficult to overcome them by the light of the
present day, when, even in England, Snails are supposed to possess a useful power in cases of lung
trouble. A full relation of all the absurdities which gained credence would form a curious and
marvelous page in the history of credulity. They have, also, from very early times, been used in
the preparation of cosmetics; and no longer than two or three centuries ago the water procured
from them by distillation was much celebrated, and empioyed by ladies to impart whiteness and
freshness to the complexion. Finally, I hear that there is celebrated in Rome, even now, a
midsummer festival, upon which oceasion all family feuds may be made up, or any differences
between friends easily adjusted, since that is the spirit of the day; and a sign or token of this
renewed friendship and good-will is the present of a Snail from one party to the other, or an
exchange of mollusks between them. The symbolism and virtue reside in the alleged amicable
influence of the head and ‘horns’—why, perhaps comparative mythologists may be able to tell us.

“In this country no such fanciful notions have ever gained credence. The Snails are too
‘habitually hidden to attract the attention of any but a few; and even when their existence is
known, they are unfortunately regarded with such a disgfist as would preclude any acceptance of
them, either for food or medicine.”

In Thomas De Voe’s “Market Assistant,” p. 312, is the following information, which refers to
about the year 1860: “From the French journals we learn that there are fifty restaurants and
more than twelve hundred private tables in Paris where Snails are accepted as a delicacy by from
eight to ten thousand consumers. The market price of the great vineyard Snails is from 2 franes
50 centimes to 3 franes 50 centimes (47 to 66 cents) per hundred, while those of the hedges, woods,
and forest bring only from 2 franes to 2 franes 25 centimes (38 to 43 cents). Snails are, and have
been for several years, imported [into New York] from Europe, but are principally used by
foreigners. They are generally stewed after having been scalded out of their shelis.”

The custom-house counts this import among “fancy groceries,” so that no separate record is
obtainable of the amount consumed. In the case of several of the large Southern species, such as
the Apple-snail (Ampularia), the Bulimi, and the large pond Snails, their remains in the shell-
heaps show that in prehistoric time they formed a regular part of the food of the red men. The
Seminoles, of Florida, and various native races west of the Rocky Mczu:ams, eat them yet.

207. THE WING-SHELLS—PTEROPODA.

The Pteropods, or wing-footed mollusks, are a small group which swim freely throughout the
broad ocean. Their shells are of small size, fragile, and semi-transparent. They form, therefore,
available food for a large number of surface-feeding fishes, and particularly of the cetacea; the
right whale, indeed, is said to live almost wholly upon certain species of them which abound in

THE BIVALVE MOLLUSKS. 703

arctic seas and swarm near the surface at night, so that he need only drop his jaw and engulf
them by the hundred in his capacious mouth as he swims along with his head half out of water.
Probably the same thing is true of the other balsnoids.

208. THE TUSK-SHELLS—SOLENOCONCHA.

The class denominated in Professor Verrill’s Check List Solenoconcha includes only one
mollusk that may concern us at present—Dentalium. This mollusk (chiefly D. pretiosum) occurs
all along the northern Pacific coast of America, and is known to Americans as the “ Tusk-shell,”
to Russians as “Sookli,” and to the Alaskan Indians as “Hya-qua.” From Northern California
all the way to the arctic regions the coast tribes collected this shell, polished it, and arranged it
on strings as money—a circulating medium of trade, similar to the wampum of the eastern coast.
There were certain rules as to fineness, arrangement, size, and measurement, which decided the
value of the shells before and after stringing; and so useful was this allocochick, as the California
Indians called it, that the Hudson’s Bay Company and other traders adopted it as current coin
in their buying and selling of peltries and provisions.

The strings of Dentalia were also worn as necklaces by the women, or twined in the hair of
both sexes; as trimming for garments, and ornaments for horse-trappings and the equipments of
war and the chase. Among other methods of employing them to enhance personal charm was to
insert two of them, point to point, from opposite sides, through a perforation in the partition
which separates the nostrils, which decoration was further increased by sticking a bright feather
in the large end of each of the hollow shells. This money is going out of use now, and only the
old Indians, conservators of ancient customs, attempt to hoard it up. A full account of it may be
found in the article upon “ Wampum” already alluded to, printed in “The American Naturalist”
for May, 1883.

209. THE BIVALVES—LAMELLIBRANCHIATA.

It is in the class of plate-gilled or lamellibranchiate mollusks, more popularly known as
“bivalves,” that we find the most examples of direct utilization by man, or immediate contribu-
tion to the fisheries. Bivalves are widespread and well-known. They afford luxuries as well as
solid nourishment for our tables, enter largely into manufactured products, serve as ornaments,
and are so beloved by food-fishes generally that they are useful as bait.

The partial list of bivalved mollusks that are ascertained to enter into the diet of Ameri-
can food-fishes includes the following, mainly from the northern Atlantic coast as in the case of
the gasteropods, and is instructive as showing how extensively fishes depend upon molluscan
food:

Ensatella americana, Crytodaria siliqua, Mya arenaria, Spisula ovalis, Macoma sabulosa, Angulus
tener, Petricola pholadiformis, Venus mercenaria, Cyprina islandica, Cardium pinnulatum, Cardium
islandicum, Cryptodon Gouldii, Venericardia borealis, Astarte quadrans, Nucula proxima, Nucula
tennis, Yoldia limatula, Yoldia sapotilla, Yoldia myalis, Yoldia thraciformis, Leda tenuisulcata,
Argina pexata, Mytilus edulis, Modiola modiolus, Modiolaria discors, Crenella glandula, Pecten

tenwicostatus, Pecten islandicus, Pecten irradians, and Ostrea virginica; to which must be added
Unio, Anodonta, and otner fresh-water bivalves, and the brachiopods Rhynconella psittacus and
Terebratulina septentrionalis.

In this list many species are of importance otherwise, and some worth notice, although not
fed upon by fishes, are not mentioned; the first to be named in this latter class is the dreaded
Ship-worm (Teredo), of which there are seven species in the United States :

704 NATURAL HISTORY OF AQUATIC ANIMALS.

Teredo navalis, Linné. Cape Cod to Florida; Sweden to Sicily.

Teredo norvegica, Spengler. Cape Cod northward.

Teredo megotara, Hanley. Massachusetts Bay to South Carolina.

Teredo dilatata, Stimpson. Massachusetts to South Carolina.

Teredo Thompsoni, Tryon. Cape Cod, Massachusetts.

Xylophaga dorsalis, Forbes and Hanley. North Atlantic.

Xylotrya fimbriata, Jeffreys. Long Island Sound to Florida; British Columbia; Europe.

The most commonly observed of these is the Teredo navalis. This is the same species that has
attracted so much attention in Europe, during nearly two centuries, on account of the great
damage that it has done, especially onthe coast of Holland. Its history has been reviewed at
length by Professor Verrill in his ‘“ Invertebrates of Vineyard Sound,” from which the present
account is principally derived.

“ Although popularly known as the ‘Ship-worm,’ these creatures are not at all related to the
worms, but are true mollusks, quite nearly allied, in many respects, to the common ‘Long Clam
(Mya) and to the Pholas. Like those shells, the Teredo exeavates its holes or burrows merely for
its own protection, and not for food; but the Teredo selects wood in which to form its holes, and
when these have been excavated it lines them with a tube of shelly material. The holes are very
small at the surface of the wood, where they were formed by the young Toredos, but they gradually
grow larger as they go deeper and deeper into the wood, until they sometimes become ten inches
or more iu length and a quarter of an inch in diameter; but the size is generally not more than
half these dimensions. The holes penetrate the wood at first perpendicularly or obliquely, but if
they enter the side of the timbers or planks across the grain the burrows generally turn horizon-
tally in the direction of the grain a short distance beneath the surface, unless prevented by some
obstruction, or by the presence of other toredo tubes, for they never cross the tubes of their
companions or interfere with each other in any way, and there is always a thin layer or partition
of wood left between the adjacent tubes. It is, however, not necessary that they sheuld follow
the grain of the wood, for they can and do penetrate it in every direction, and sometimes not more
than half the tubes run in the direction of the grain, and they are often very crooked or even
tortuous. They rapidly form their burrows in all kinds of our native woods, from the softest pine
to the hardest oak, and although they usually turn aside and go around hard knots, they are also
able to penetrate through even the hardest knots in oak and other hard woods. The Teredos
grow very rapidly, apparently attaining maturity in one season, and therefore, when abundant,
they may greatly damage or completely destroy small timber in the course of four or five months,
and even the largest piles may be destroyed by them in the course of two orthree years.

‘“¢ When removed from its tube the animal is found to have a very long, slender, smooth, soft,
whitish body, tapering somewhat toward the outer or posterior end, which has a muscular, circularly
wrinkled collar, by which the animal is, when living, attached to the inside of the shelly lining of
its tube. To the inside of this collar two shelly plates, known as the ‘pallets,’ are attached by
their slender basal prolongations; their outer portions are broad and flat, and more or less
emarginate or two-horned at the end. These are so connected with the muscles that when the
animal withdraws its tubes into its hole the free ends of these pallets are made to fold together
and close the opening, thus serving as an operculum to protect the soft tubes against enemies of
all kinds. Between the bases of the pallets arise the siphonal tubes, which are soft and retractile,
united together for half their length or more, but separate and divergent beyond; they are nearly
equal, but the ventral or branchial tube is perhaps a little larger than the other, and is fringed
with a few small papille at the end. The tubes are white or yellowish, sometimes speckled with

a

HABITS OF THE SHIP-WORMS. 705

reddish-brown. At the anterior end of the body, and farthest from the external opening of the
hole, is seen the small but elegantly sculptured white bivalve shell. The shell covers the mouth
and palpi, liver, foot, and other important organs. The foot is a short. stout, muscular organ,
broadly truncate or rounded at the end, and appears to be the organ by means of which the
excavation of the burrow is effected. The shell is covered by a delicate epidermis, and probably
does not assist in rasping off the wood, as many have supposed. The gills are long and narrow,
inclosed mostly in the naked part of the body, and are reddish-brown in color.

“The Teredos obtain their microscopic food in the same manner as other bivalve mollusks, viz,
by means of a current of water constantly drawn into the branchial tube by the action of vibrating
cilia within; the infusoria and other minute organisms are thus carried along to the mouth at the
other end, while the, gills are supplied with oxygen by the same current; the return current
passing out of the dorsal tube removes the waste water from the gills, together with the fzces
and excretions of the animal, and also the particles of wood which have been removed by the
excavating process.

‘As the animal grows larger the burrows are deepened, the lining of shelly matter increases
in length and thickness, the shell itself and the pallets increase in size, and the terminal tubes
grow longer. But as the orifices of the terminal tubes must necessarily be kept at the external
opening of the burrow, the muscular collar at the base of the tubes constantly recedes from the
entrance, and with it the pallets; at the same time imbricated layers of shelly matter are usually
deposited in the upper end of the shelly tube, which are supposed to aid the pallets in closing the
aperture when the tubes are withdrawn. When the animal has completed its growth, or when it
has encountered the tubes of its companions and cannot pass them, or when it approaches the
exterior of a thin piece of wood and cannot turn aside, it forms a rounded or cup-shaped layer
of shelly matter, continuous with the lining of the tubes and closing up the burrow in front of
its shell. Sometimes it retreats and forms a second partition of the same kind.

“This species produces its young in May and probably through the greater part or all of the
summer. The eggs are exceedingly numerous, probably amounting to millions, and they are
retained in the gill-cavity, where they are fertilized and undergo the first stages of their develop-
ment. The embryos pass through several curious phases during their growth. In one of the
early stages they are covered with fine vibrating cilia, by means of which they can swim like
ciliated infusoria; later they lose these cilia and develop a rudimentary bivalve shell, which is at
first heart-shaped, and the mantle begins to appear and larger retractile cilia develop upon its
edge, which serve as organs for swimming; but at this period the shell is large enough to cover
the whole body when contracted. In this stage they swim actively about in the water; later the
cilia become larger, a long, narrow, ligulate foot is developed, by means of which they can creep
about and attach themselves temporarily to solid objects; the shells become rounder, a pair of
eyes and organs of hearing are developed. After this the little animal begins to elongate, the
locomotive cilia are lost, the eyes disappear, and the mature form is gradually assumed. These
young Teredos, when they finally locate upon the surface of wood-work and begin to make their
burrows, are not larger than the head of a pin, and consequently their holes are at frst very
minute, but owing to their rapid growth the holes quickly become larger and deeper.” !

This species is very abundant along the southern coast of New England, from New York to
Cape Cod, wherever submerged wood-work, sunken wrecks, timber buoys, or floating pieces of
driftwood occur. It also infests the bottoms of vessels not protected by sheathing. At Province-
town, Cape Cod, about forty feet of the end of the steamboat wharf was so weakened by its

' Report, U. 8. Fish Commission, part i, 1873, pp. 384-386.
45 F

706 NATURAL HISTORY OF AQUATIC ANIMALS.

borings that it completely gave way under a ship-load of merchandise stored upon it. This pest
is not confined to pure sea-water, but occurs in the piles and timbers of wharves in harbors that
are not only brackish, but also muddy and contaminated with sewage. Capt. B. J. Edwards
told me that formerly when the cedar channel-buoys in Buzzard’s Bay, Massachusetts, were not
taken up they would last not more than two years, owing chiefly to the attacks of this Teredo;
but under the present system there are two sets of buoys, which are alternately taken up and
put down every six months. After a set has been allowed to dry thoroughly they are scraped
to remove the barnacles, etc., and then receive a thorough coat of verdigris paint each time
before they are put down. With this treatment they will last ten or twelve years, but they
are more or less perforated and injured every year, until finally they become worthless. This
statement does not apply to the spar-buoys, which are taken up only once a year, in April
and May. Captain Edwards says that the Teredos would destroy an unpainted spar-buoy in
one year, but when painted with verdigris they will only work where the paint becomes rubbed
off. They first attack buoys or piles just below the water’s edge, but eventually will destroy
the entire submerged wooden portion. Commenting upon this information, Professor Verrill says:

“Tnasmuch as the Teredos produce their young all through the summer, and they develope to
a very large size in one season, it is evident that the best time to take up the buoys would be in
midsummer, before the early crop of young have grown large, and leaving too little time for the
later crop to become large, in the buoys thus put down, before winter, when most of them would
probably be killed by the cold weather. In this way the damage might be materially diminished,
if not inconsistent with the other duties of the officers of the vessels employed in this service.
There are, as yet, no means of estimating the extent of the damage done to our wharves, shipping,
ete., by this and the various other species of Teredo found on our coast, but, judging from their
abundance along the whole coast, it is much greater than is generally supposed.

“The Teredo navalis is also abundant on the coast of Europe, from the Mediterranean and
Black seas to Christiania and the coasts of Great Britain. Its habits have been quite thor-
oughly investigated by several Dutch naturalists, owing to the great damage that it has done
on their coast, at times even threatening a general inundation of the country by destroying the
wood-work of the dikes. This Teredo occupies a zone of considerable breadth, for it often lives
considerably above low-water mark, and extends several feet below it, even to the depth of four-
teen feet, according to some writers.

“The best remedies in common use to resist or prevent its attacks are copper sheathing, used
chiefly on vessels; broad-headed nails, closely driven, used for piles and timbers; creosote and
coal-tar, frequently applied. The various poisonous substances that have been applied to timber
for this purpose, however useful they may be in other respects, have little or no effect on the
Teredo, for it does not depend upon the wood for its food, and even protects its body externally
with a layer of shell, lining its holes. The only remedies that are likely to succeed are those
calculated to prevent the lodgment and entrance of the young ones beneath the surface. Even
creosote, thoroughly applied under pressure at the rate of ten pounds per square foot, has been
found insufficient to prevent their attacks, for piles thus treated at Christiania were found by Mr.
Jeffreys to be filled with the Teredo within two years after they were put down.

‘‘Several other species of Teredo also occur on this coast. The Teredo megotara has been found
in floating pine wood at Newport, Rhode Island, and in cedar buoys, ete., at New Bedford, Massa-
chusetts; as well as in Massachusetts Bay, at Provincetown, and other places; it is also found as
far south as South Carolina at least. This species sometimes grows to a large size, forming tubes
at least eighteen inches long. It sometimes occurs, also, in the piles of wharves in this region

THE CLAMS. 707

{Vineyard Sound, Massachusetts]. The Zeredo Thomsoni has been found in great numbers in
the marine railway and also in cedar buoys at New Bedford. It has also been found at
Provincetown in a whaling-ship that had cruised in the West Indies.

“The Xylotrya Jimbriata is very similar to the common Toredo, except that it has long, oar-
shaped pallets, with slender stalks; the blade is flattened on the inside and convex externally,
and consists of ten to twelve or more funnel-shaped segments which set one into another; their
margins project at the sides, making the edges of the blade appear serrated. This species appears
to be indigenous on this coast. It has been found living in a sunken wreck in Long Island Sound,
near New Haven, and I have also taken it from the oak timbers of a vessel, the ‘“Peterhoft,”
employed in the blockading service, during the late war, on the coast of the Southern States. It
grows to a rather large size, often forming holes a foot or more in length and a quarter of an inch
in diameter, though usually smaller. The pallets are sometimes half an inch long.”

Less likely to be mistaken for worms, but equally clever at boring, is a group of shells called
Pholads, from the Greek word gwiégw, lurking. They perforate all substances that are softer than
their own valves, and some that seem to be harder. Woodward says: “It is to be remarked that
the condition of the Pholades is always related to the nature of the material in which they are
found burrowing; in soft sea-beds they attain the largest size and greatest perfection, whilst in
hard and especially gritty rock they are dwarfed in size and all prominent points and ridges
appear worn by friction.” The Pholads have white sheJls, generally very thin but hard and
strong, and adorned with rasp-like sculpture. It was supposed formerly that the excavation was
made by twisting and moving this rough shell in the burrow; but the muscular, club-shaped foot
is no doubt the instrument of abrasion. :

We have upon the east coast three species, but none of them are of practical importance.
They might become available for food, however, since the same mollusks are eaten in the southern
counties of England, where they are called “Piddocks,” and some cousins (Zirphea crispata,
Platydon cancellatus, etc.) are esteemed delicacies ou the coast of California under the name of
‘“<Date-fish.” Other west-coast species (Navea, Gastrochena, etc.) are enemies of the Oyster,
Abalone, and other mollusks which themselves have a commercial importance, since they burrow
into their shells and so ruin them for service to man. ‘There is, nevertheless, an attendant
advantage in this, since in a state of nature the Pholads thus break to pieces and tend to level
reefs that would prove obstructive to navigation, particularly in the case of coral banks. When
the object leveled is an expensive dike or breakwater, however, the result is exactly reversed, as

it is very likely to be where man’s arts attempt to change the natural arrangement of things.

Our Razor-shell (Hnsatella americana) is frequently used for food in Europe and in New
England, and its valves have occasionally been applied to artistic service. It passes under the
various names of “ Razor-fish,” ‘“‘ Razor-clam,” ‘ Knife-handle,” ete., and is enticed from its sandy
burrow by sprinkling salt upon the sand under which it lies, or is rooted out with a spade. John
_Josselyn, Gent., records that its “shell, calcin’d and pulveriz’d, is excellent to take off a pin and
web, or any kind of filme growing over the eye.” The Californian Razor-fish (Siliqua patula) is
also edible.

Next upon the list comes the “Soft Clam,” “‘ Long Clam,” or “‘ Nanninose” (Mya arenaria),
dear to New Englanders and only less numerous than the Hard Clam in the markets of New York
and Philadelphia. This Clam lives just beneath the surface of the sand and mud above low-water

mark, and is easily dug out with ahand-shovel. A very large class of persons all along the shore
from Maine to Delaware derive their living wholly or in part by digging it and shipping to city
markets. This is chiefly the case north of New York, however. On the northern coasts of New

708 NATURAL HISTORY OF AQUATIC ANIMALS.

England immense quantities of this bivalve are collected and salted to be used as bait in the
cod fishery. Statistics and a full discussion of the habits and artificial culture of this Clam will
be found in the special chapter devoted to the Clams.

Washed up by storms from the deep sands—down at least to ten fathoms below the low-water
line—and hence known as the ‘“ Beach,” “Sea,” or “Surf” Clam, the huge Spisula solidissima
furnishes occasional repasts to the dwellers along the whole Atlantic shore. It is chiefly eaten in
Massachusetts, however, and its flesh is tough and by some persons considered unwholesome. Tt
is often cast up in such great quantities as to become available for manure, mixed with various
other marine animals of all sorts and sizes and much sea-weed. The large, smooth, white valves
are collected in considerable quantities to be decorated inside with pictures in oil or India ink,
which are again sold in the picture stores, often for a good price. This Clam is also preserved as
bait. On the Pacific coast an allied species (Spisula falcata) serves the various purposes to
which the eastern one is applied.

Following this comes the Quahaug (Venus mercenaria), which is known in the markets as
“ Hard Clam,” “ Round Clam,” or, in New York, simply “Clam.” From Cape Cod to Florida it is
very abundant, but must be gathered by raking, since it does not burrow in the shore-sands like
the Soft Clam. A commerce still larger than in the case of the Soft Clam is carried on with
this species as bait, and also for food, in which respect it ranks next to the Oyster in the Umited
States.

On the Pacific coast—where eastern shell-fish are constantly sent for transplantation and for
immediate consumption—there are various bivalves used as food, such as Semele decisa, the ‘“ Flat
Clam”; Macoma nasuta, the “Tellens,” of San Francisco; Schizotherus Nuttalli, the ‘“Gaper”;
Chione succincta, and allied species, which replace eastern ‘Little Necks”; and Savidomus aratus,
to relish which was learned from the Indians.

In regard to this latter mollusk (Saridomus aratus) it is interesting to note rhat its shell was
broken into pieces by the Indians of the California coast and worked into flat, cireular disks by
rubbing upon stone. EKighty of these disks strung upon sinews were in recent use by the Indians
of Lake County, California, as a medium of exchange in trade, and were valued at one dollar. In
Sonoma County Saxidomus gracilis seems to have served the same purpose.

Another form of aboriginal money was made from the valves of the ponderous Hen Clam of
southern California (Pachydesma crassatelloides), already mentioned. This money was called
‘“‘hawok,” and took the shape of perforated disks which could be strung as beads. The larger
pieces, according to Stearns, were worth twenty-five cents, and were cut from the thicker parts
of the shell; while the thinner portions supplied beads worth only four cents each. Further
information will be found upon this in my magazine article above referred to.

The Pachydesma and its neighbor, the Cardium Nuttalli, are considered edible by the west
coast people; but on the Atlantic shore, where occur several large species of “Cockle” (as the
members of the genera Cardium, Astarte, Venericardia, and the like, are called), they are ranely or
never used as food. This neglect seems curious, since this mollusk is eaten in great abundance in
England, and may be bought everywhere in London during summer. ‘ Prodigious quantities of
this shell-fish are also consumed in Holland, where their cheapness recommends them to the
common people as a principal article of food during the winter.” In New England Cyprina islandica
is eaten now and then, but bears a poor reputation in comparison with the Quahaug. In the
Southern States the large “ Painted Clam” (Callista gigantea) is equally available as food, and the
Gnathodon cuneatus of the Gulf of Mexico is already an article of diet, as well as useful in road-
making, to which utility many other mollusks contribute in all sea-shore towns.

THE MUSSELS. TO9

These thick-shelled bivalves disposed of, a large group of thin-shelled mollusks deserve
notice. Foremost among these are the Mussels, which are of several kinds. In Burope the Mytilus
edulis (which is not different from our common Black Mussel of both the east and west coasts) holds
an important place among sea-foods. In 1873 the mussel fishery of France alone was worth over
800,000 franes ($160,000). In that country they are regularly bred in inclosures of sea-water,
upon frames and hanging ropes constructed for the purpose, and many persons are employed.
Tn England, Scotland, Ireland, along the Mediterranean, in the West Indies, and along the whole
circumference of South America, edible species of one name or another grow. Our Mytilus edulis
is cireumpolar in its distribution, and is excessively numerous at all rocky points suitable for its
growth. In New York it is pickled in large quantities and shipped throughout the interior of the
country. Its shells are extensively used by oyster-planters as a cultch upon which to catch young
Oysters, and when polished are made into paint-holders for artists and various articles of bijouterie
and personal ornament. The American Indians and the native New Zealanders used them as
tweezers in pulling out their beards.

Mussels of a different sort are the Modiola plicatula, the Modiola modiolus, the Modiola hamatus,
and Modiola capax; the first two are of the northern Atlantic, the third is more southern, and
the fourth a native of California. These are sometimes eaten, but are not considered so good as
the WM. edulis. On the coasts of New Jersey and Long Island, however, incredible quantities are
gathered from the banks at the inlets through the outer beaches where they grow, and are spread
upon sea-shore farms as manure. In gathering this fertilizer a large number of vessels and men
find irregular employment at times when they would otherwise be idle.

Another important bivalve in a commercial way is the Scallop, fisheries for which flourish in
Long Island Sound, Narragansett Bay, and elsewhere. Large fleets of vessels are engaged in
summer in dredging for these shell-fish. The powerful central muscle by which the animal opens
and closes its shells forms the edible portion, the rest being discarded. These white fragments are
to be seen piled upon platters or strung in strings as a constant delicacy in all our markets. The
common. Scallop of commerce is the Pecten irradians. Years ago the very large species, Pecten
islandicus, an inhabitant of Eastern Maine and the Bay of Fundy, used to be obtained, and was
highly prized for its flavor, but it has long been too rare to serve any purpose other than as a
curiosity to conchologists. A more common and useful species, north of Cape Cod, is Pecten tenw-
costatus, which supplied the Indians with a culinary instrument, and is good food.

“Scallop shells were formerly worn by pilgrims on their hat or the cape of their coat, as a
mark of their having crossed the sea for the purpose of paying their devotions at the holy shrine
in Palestine; in commemoration of which they are still preserved in the armorial bearings of many
families of distinction whose ancestors had performed that ceremony. From its use by cooks
now, this shell has given the name to ‘scalloped’ Oysters. In early times, when plates and drink-
ing-vessels were not so plentiful as they are now, the concave or hollow valve of the Scallop served

as a cup, and the flat valve for a plate. The idea has even been carried out by our pottery man-
ufacturers, and plates and dishes have been molded after the forms of bivalve shells. Reticules,
needle-books, pincushions, and other articles are made by shell-dealers with the scallop shell.”
: Of both the Scallop and the Mussel a special account will be given in another place, con-
sidering the value of each commercially.

The fresh-water bivalves belonging to the large family of the Unionide ought not to be
“omitted in this review. To the raccoon, otter, muskrat, aud many other mammals and birds, as well
as to the fishes, they are a steady source of food. Observing this, the Indians adopted them from
the earliest prehistoric times as edible, and enormous heaps of shells upon the banks of many

710 NATURAL HISTORY OF AQUATIC ANIMALS.

of our interior rivers, especially in Pennsylvania, the Ohio Valley, and the Southern States, show
how extensively and constantly they were sought. White men occasionally eat them, and in case
of extreme hunger would perhaps pronounce a roasted Unio or Anodonta good. Some years ago a
great furore was created by the discovery of a fine pearl in one of the Unios of North Carolina—a
thing likely to happen in the case of any of them, since they have an interior which is often as finely
nacreous as that of the Mother-of-pearl Oyster of the Gulf of California. Hundreds of persons
immediately began searching the rivers all over that region, and total extirpation of the poor Mus-
sels was prevented only by the discouragement of finding few pearls and these of insignificant
size. It is probable that from the heavier species, in captivity, good pearls might be obtained
artificially by following the plan pursued by the Chinese with their sea Pearl-oyster. The experi-
ment is worth trying.

Shells of fresh-water Mussels are frequently worked up into pocket-books and other fancy arti-
cles, as in the case of the Mytilus. When the brown epidermis is removed a beautiful iridescent
polish is obtainable. There are almost innumerable varieties of these fresh-water Mussels, and
full cabinets have a considerable value. e

The manufacture of jewelry and shell-flowers consumes large quantities of small shells and
and the polished opercula of large ones, chiefly derived from Florida. It is said that in London
about a million of the commoner sorts are sold to street-sellers and country peddlers, who retail
them to be made into fancy work and as objects of curiosity. The same thing is frequently seen
in the United States, though more commonly in the shape of the traveling dealer who brings
a large and varied stock to a country town, hires a shop for several weeks, and sells his shells
mainly by auction.

The spread of commerce and improved facilities for dredging have made species once rare now
common; but astonishing prices, reaching hundreds of dollars for a single specimen, in some cases
were paid by owners of conchological cabinets for rare species half a century ago. This stimulated
research and distributed much money among sea-side collectors. Even now dealers in objects of
of natural history derive a large profit by importing shells whose only value is their scientific
importance; while the institutions devoted to their study and the books to which an interest in
conchology have given rise are entitled to a money estimation not to be despised.

A CONTRIBUTION TO THE LIFE-HISTORY OF THE OYSTER.
(Ostrea virginica, Gmelin, and O. edulis, Linn.)
By JoHN A. RYDER.
210. OUTLINE SKETCH OF THE COARSER ANATOMY OF THE OYSTER.

“The general structure of an Oyster may be roughly represented by a long, narrow memorandum
book, with the back at one of the narrow ends instead of at one of the long ones. The covers of
such a book represent the two shells of the Oyster, and the back represents the hinge, or the
area where the two valves of the shell are fastened together by the hinge ligament. This ligament
is an elastic, dark-brown structure, which is placed in such a relation to the valves of the shell
that it tends to throw their free ends a little apart. In order to understand its manner of working,
open the memorandum book and place between its leaves, close to the back, a small piece of
rubber to represent the ligament. If the free ends of the cover are pulied together the rubber ,
will be compressed and will throw the covers apart as soon as they are loosened. The ligament
of the oyster-shell tends, by its elasticity, to keep the shell open at all times, and while the
Oyster is lying undisturbed upon the bottom, or when its muscle is cut, or when the animal is
dying or dead, the edges of the shell are separated a little.

“The shell is lined by a thin membrane, the mantle, which folds down on each side, and may
be compared to the leat next the cover on each side of the book. The next two leaves of each
side roughiy represent the four gills, the so-called ‘beard’ of the Oyster, which hang down like
leaves into the space inside the two lobes of the mantle. The remaining leaves may be compared
to the body or visceral mass of the Oyster.

“ Although the Oyster lies upon the bottom, with one shell above and one below, the shells
are not upon the top and bottom of the body, but upon the right and left sides. The two shells
are symmetrical in the young Oyster, but after it becomes attached the lower or attached side
grows faster than the other, and becomes deep and spoon-shaped, while the free valve remains
nearly flat. In nearly every case the lower or deep valve is the left. As the hinge marks the
anterior end of the body, an Oyster which is held on edge, with the hinge away from the observer
and the flat valve on the right side, will be placed with its dorsal surface uppermost, its ventral
surface below, its anterior end away from the observer, and its posterior end toward him, and its
right and left sides on his right and left hands, respectively.

‘In order to examine the soft parts, the Oyster should be opened by gently working a thin, flat
knife-blade under the posterior end of the right valve of the shell, and pushing the blade forward
until it strikes and cuts the strong adductor muscle, which passes from one shell to another and
pulls them together. As soon as this muscle is cut the valves separate a little, and the right
valve may be raised up and broken off from the left, thus exposing the right side of the body.
‘he surface of the body is covered by the mantle, a thin membrane which is attached to the body
‘over a great part of its surface, but hangs free like a curtain around nearly the whole circum-

ference, By raising its edge, or gently tearing the whole right half away from the body, the gills
711

712 NATURAL HISTORY OF AQUATIC ANIMALS.

will be exposed. These are four parallel plates which occupy the ventral half of the mantle cavity
and extend from the posterior nearly to the anterior end of the body. Their ventral edges are
free, but their dorsal edges are united to each other, to the mantle, and to the body. The space
above, or dorsal to the posterior ends of the gills, is oceupied by the oval, firm adductor muscle,
the so-called ‘heart.’ For some time I was ata loss to know how the muscle came to be called
the ‘heart,’ but a friend told me that he had always supposed that this was the heart, since the
Oyster dies when it is injured. The supposed ‘death’ is simply the opening of the shell when the
animal loses the power to keep it shut. Between this muscle and the hinge the space above the
gills is occupied by the body, or visceral mass, which is made up mainly of the light-colored repro-
ductive organs and the dark-colored digestive organs, packed together in one continuous mass.

“Tf the Oyster has been opened very carefully, a transparent, crescent-shaped space will be
seen between the muscle and the visceral mass. This space is the pericardium, and if the delicate
membrane which forms its sides be carefully cut away, the heart may be found without any
difficulty, lying in this cavity, and pulsating slowly. If the Oyster has been opened roughly, or
if it has been out of water for some time, the rate of beating may be as low as one a minute,
or even less, so the heart must be watched attentively for some time in order to see one of
the contractions.” !

The dark-purple scars near the centers of both valves are simply the areas covered by the
attachments of the adductor, which is composed of a vast number of extremely fine muscular

“fibers, which collectively pass straight across the space between the inside of the valves, being
firmly fixed at either end of the latter. The tendency to separate the valves at their free borders,
inherent in the ligament, is balanced or counteracted by the muscle. The head end of the animal
lies close against the hinge, the point where, as previously described, the two valves are firmly
fixed to each other by a dark-brown, crescent-shaped body, the ligament, which, while it serves to
attach, also tends, by reason of its elastic properties, to cause the valves to separate at their free
borders in order to allow the passage of the water inward to the gills, and of food to the mouth,
while it also allows the water which has passed through the gills to escape by way of the cavity
above the gills which is prolonged into the cloaca, carrying along with it, in its outward passage,
the feces from the vent. The foregoing lines fairly describe the mechanism of the shell and in
part the physiological significance of the same.

The structure of the shell is laminar, or, in other words, it is composed of numerous layers of
a material identical in composition with chalk, deposited one on the other by the mantle, the organ
which builds the whole shell in this way, the chalky substance being derived from the fluids of the
animal, which in turn derives it from its food. These layers, deposited as they are internally, in
a horny organic matrix, as growth proceeds project in succession past each other at the free edges
of the valves and external surface of the shell, so that the successive deposits may readily be
distinguished on its external surface, giving rise to a very rough imbricated appearance of the
edges of the layers on the outside. Attempts which I have made to determine the age of Oysters
from a supposed periodic deposition of the shelly material, corresponding to the years of its age, J
find to be impracticable.

The structure in the layers of the shell of the chalk or caleic carbonate is minutely prismatic,
Nathusius-K6nigsborn has found that certain portions of the shell of the European Oyster contain
very minute air-spaces. Both native and foreign species are found to have hollow cavities in the
valves, usually containing water.

'W. K. Brooks: Deyelopment of the American Oyster. Studies from the Biological Laboratory of Johns Hopkins
University, No. IV, 1880, pp. 5-7. $

THE ANATOMY OF THE OYSTER. 713

“Yn front of the gills, that is, between them and the hinge, there are four fleshy flaps—the
lips—two on each side of the body. They are much like the gills in appearance, and they are
connected with each other by two ridges which run across the middle of the body close to the
anterior end, and between these folds is the large oval mouth, which is thus seen to be situated,
not at the open end of the shell, but as far away from it as possible. As the Oyster is immovably
fixed upon the bottom, and has no arms or other structures for seizing food and carrying it to the
mouth, the question how it obtains its food at once suggests itself. If a fragment of one of the gills
is examined with a microscope it will be found to be covered with very small hairs, or cilia,
arranged in rows. Each of these cilia is constantly swinging back and forth, with a motion
something like that of an oar in rowing. The motion is quick and strong in one direction and
slower in the other. As all the cilia of a row swing together, they act like a line of oars, only they
are fastened to the gill, and as this is immovable, they do not move forward through the water, but
produce a current of water in the opposite direction. This action is not directed by the animal,
for it can be observed for hours in a fragment cut out of the gill, and if such a fragment be supplied
with fresh sea-water, the motion will continue until it begins to decay. While the Oyster lies
undisturbed on the bottom, with its muscle relaxed and its shell open, the sea-water is drawn on
to the gills by the action of the cilia, for although each cilium is too small to be seen without a
microscope, they cover the gills in such great numbers that their united action produces quite a
vigorous stream of water, which is drawn through the shell and is then forced through very small
openings on the surfaces of the gills into the water-tubes, inside the gills, and through these tubes
into the cavity above them, and so out of the shell again. As the stream of water passes through
the gills the blood is aérated by contact with it. The food of the Oyster consists entirely of minute
animal and vegetable organisms and small particles of organized matter. Ordinary sea-water
contains an abundance of this sort of food, which is drawn into the gills with the water, but as the
water strains through the pores into the water-tubes, the food particles are caught on the surface
of the gills by a layer of adhesive slime which covers all the soft parts of the body. As soon as
they are entangled the cilia strike against them in such a way as to roll or slide them along the
gills toward the mouth. When they reach the anterior ends of the gills they are pushed off and
fall between the lips, and these again are covered with cilia, which carry the particles forward
until they slide into the mouth, which is always wide open and ciliated, so as to draw the food
through the wsophagus into the stomach. Whenever the shell is open these cilia are in action,
and as Jong as the Oyster is breathing a current of food is sliding into its mouth.

“The cilia and-particles of food are too small to be seen without a microscope, but if finely
powdered carmine be sprinkled over the gills of a fresh Oyster, which has been carefully opened
and placed in a shallow dish of sea-water, careful observation will show that as soon as the colored
particles touch the gills they begin to slide along with a motion which is quite uniform, but not
much faster than that of the minute-hand of a watch. This slow, steady, gliding motion, without

any visible cause, is a very striking sight, and with a little care the particles may be followed up

to and into the mouth.
‘““In order to trace the course of the digestive organs, the visceral mass may be split with a

sharp knife or razor. If the split is pretty near the middle of the body, each half will show
“sections of the short, folded csophagus, running upward from the mouth, and the irregular

n: :
pe

nts by the section.

_ “There are no accessory organs of reproduction, and the position, form, and general appear-

te
a“

(14 NATURAL HISTORY OF AQUATIC ANIMALS.

ance of the reproductive organ is the same in both sexes. There is no characteristic by which a
male Oyster can be distinguished from a female, without microscopic examination. As the repro-
ductive organ has an opening on each side of the body, it is usually spoken of as double, but in
the adult Oyster it forms one continuous mass, with no trace of a division into halves, and extends
entirely across the body and [against] the bends and folds of the digestive tract.” 1

(The last of the foregoing statements as to the impossibility of discriminating the sexes with-
out the aid of the microscope is no longer true, though it was true at the time the above was
written. The method of discriminating the sexes discovered by the writer is discussed in another
portion of this sketch of the history of the Oyster.)

The stomach is pretty definitely marked off from the other portions of the digestive tract. It
may be said to be that portion of the latter which is surrounded by the liver. The portion of the
intestine immediately following the short widened region which we regarded as the stomach is the
most spacious portion of the gut, and in it is lodged a very singular organ which has been called
the “erystalline style.” This is an opalescent rod of a glass-like transparency and gelatinous
consistence which measures, according to the size of the Oyster, from half an inch up to one and
a half inches in length. Its anterior end is the largest, and in a large specimen measures nearly
an eighth of an inch in diameter, but at its posterior end is scarcely half as thick; both ends are
bluntly rounded. I fell into an error in supposing that this style was lodged in a special pouch
or sac as described in my report to the Maryland commissioner in 1880. The “crystalline style”
really lies in the first portion of the intestine and extends from the pyloric end of the stomach to
the first bend of the intestine, where there is a marked constriction of the alimentary canal. It
appears therefore to be a sort of loose valve in the cavity of the gut; its function may be to
prevent coarse particles of food from passing, or it may in some way assist digestion. In speci-
mens hardened in acid or alcohol this rod is destroyed, or at least disappears, so that I have been
unable to find it. The greater portion of its substance is apparently made up of water.

The peculiar d ouble induplication of the wall of the intestine is described in another place.
The fecal matters are extru ded in the form of a demi-cylinder, with one side excavated in a groove-
like manner. This shape of the feecal matters is due to the presence of the double fold. The fzeces
themselves are composed of extremely fine particles of quartz or sand grains, the tests of diatoms,
organic matters, hu mus, cellulose, fragments of the chitinous coverings of some of the minute
worms and articulates, etc., which have been swallowed and digested by the animal. The anus
is situated on the dorsal side of the great adductor muscle where the intestine ends. ¢

The organs of sensation of the Oyster, though not very highly developed, are of sufficient
importance to merit attention. The auditory sense, although I have never been able to dissect out
the auditory vesicles, I am satisfied exists, because one cannot noisily approach an Oyster bank
where the Oysters are feeding without their hearing so that instantly every shell is closed. The
tentacles of the mantle are often extended until their tips reach beyond the edges of the valves.
If the animal in this condition is exposed to a strong light the shadow of the hand passing over it
is a sufficient stimulus to cause it to retract the mantle and tentacles and to close its parted valves.
The mantle incloses, like a curtain, the internal organs of the creature on either side, and lies next
the shell, and, as already stated, secretes and deposits the layers of calcic carbonate composing
the latter. The free edges of the mantle, which are purplish, are garnished with small, highly
sensitive tentacles of the same color. These tentacles are ciliated and serve as organs of touch,
and also appear to be to some extent sensitive to light. :

''W. K. Brooks: Op. cit., pp. 8-10.

THE INTERNAL STRUCTURE OF THE OYSTER. 715

The nervous system of the Oyster is very simple, and, as elsewhere stated, is to some extent
degenerate in character. It is composed of a pair of ganglia or knots of nervous matter, which lie
just over the gullet, and from these a pair of nervous cords pass backward, one on each side, to
join the hinder pair which lie just beneath the adductor muscle. The mantle receives nerve
branches from the hindmost ganglia or knots of nervous matter; these, as their centers, control the
contraction and elongation of the radiating bundles of muscular fibers, as well as those which lie
lengthwise along the margin; the former contract and withdraw the edges of the mantle from the
margin of the shell, while the latter in contracting tend to crimp or fold its edges. The tentacles
are mainly innervated by fibers emanating from the hindmost ganglia, while the internal organs
are innervated from the head or cephalic ganglia. The hind ganglia also preside over the
contractions of the great adductor muscle. The nerve threads which radiate outward from it to
the tentacles dispatch the warnings when intruders are at hand that it must contract and close
the shells.

211. THE MINUTE ANATOMY OF THE OYSTER.

There is a spacious segmentation cavity developed in the embryo which becomes the
subdivided body-cavity—schizoccel of later stages. Between the ectoderm and endoderm the
mesoblastic tissue is developed apparently by proliferation, so that the segmentation or body
cavity becomes in part obliterated. The mesoblast of the embryo formed as above stated is the
tissue from which the mesenchyme or connective tissue of the adult is developed. The blood
channels or canals are developed in the mesenchyme of the adult—mesoblast of the embryo.
The large, coarse vesicular connective tissue cells form a sort of trabecular network of pillars and
transverse supports between and around which the sanguineous fluids circulate. The blood
channels or canals are developed directly from the spaces between the columns and their
conjoining masses of connective tissue cells; an exception to this is found only in the structure
of the anterior and posterior aorte, the heart, and branchiocardiac vessels, which have proper
walls lined with endothelial cells. Throughout the greater part of its extent the mesenchymal or
connective tissue is spongy, its cells being built around complex anastomosing spaces for the
blood. There is, therefore, a true schizoccel developed in the Oyster; it has been formed as the
mesoblastic tissue has grown into the segmentation cavity and subdivided the latter into hamal
canals and spaces. The blood cells originate in all probability in the same way. These are
ameceboid, colorless, and measure about one three-thousandth of an inch in diameter. The vascular
channels have no specialized endothelial walls in the mesenchymal parts of the body.

The adductor muscle of the shell and the radiating muscular bundles running from the
insertion of the former to the edge of the mantle are derived from the mesoblastic cells of the
embryo, the observations of Dr. Horst on this point having, I think, completely set at rest what
was formerly a matter of theory. The radiating muscular bundles—pallial muscles—of the adult
lie just beneath the epiblast or epithelium on the outer sides of the mantle leaves. These pallial
“muscles in the émbryo are represented by two sets of dorsal and ventral muscular bundles, the
functions of which are to retract the velum into which they are inserted. The muscular fibers of

the walls of the heart are not striated and decussate in every direction. The inner walls of the
heart are crossed in various directions by muscular bands or trabecule, and a more or less
complete muscular septum divides the ventricle in the median line; the heart is, therefore,

approximately four-chambered.
The mesenchymal or mesoblastic tissues comprise the great bulk of the body of the animal,
and extend out into and form the greatest proportion of the thickness of the mantle, and also

116 NATURAL HISTURY OF AQUATIC ANIMALS.

down into the branchial sacs between their epiblastic or epithelial, ciliated, external walls. It
also forms the principal bulk of the thick vertical, transverse septa which subdivide the branchial
pouches internally, and forms likewise the bulk of the branchial filaments themselves. These
latter are numerous and give the surface of the gills their furrowed or plaited appearance. The
individual plaits or ridges seen in section are found to be quite complex and to be themselves
compoundly ribbed and to have chitinous rods embedded in their substance just beneath the
external epithelium. These rods run lengthwise through the substance of the branchial riblets.
The branchial capillaries are excavated in the mesenchymal or connective tissue of the branchial
filaments or tentacles, between which there are numerous openings or ostia for the passage of the
water from the inferior portion of the pallial chamber into the gill cavities in order to effect
respiration. It is difficult, however, to make this arrangement understood without the aid of
figures.

The mesenchyme also gives support to all of the visceral structures, the ultimate secretory
follicles or saccules of the liver being imbedded and supported by it. The same is true of the
generative structures and the intestine. No portion of the walls of the stomach, @sophagus, or
hepatic ducts can be found the walls of which do not lie directly in contact with this mesenchymal
or mesoblastie tissue. It also extends out into and forms the greater proportion of the substance
of the palps or lips of the Oyster, and is very spongy and highly vascular in this region. The
internal or oral surface only of the palps or lips are closely plaited with numerous folds of ciliated
epithelium. These folds may number from one hundred and twenty-five or more. The surface of
the palps in the immediate vicinity of the mouth is not plaited or folded.

The mesenchymal cells are much larger than eitber the epithelial or endothelial cells, and will
average one five-hundredth of an inch in diameter. They inclose in all cases, both in winter and
summer, a large, irregular nucleus from which a complex network of intracellular granular fibrils
radiate in all directions through the enveloping cellular substance. At one side of the nucleus
there are always one or more accessory bodies, perfectly globular, which complicate the character
of the nucleus in a singular manner. These vesicular, very hygroscopic, mesenchymal or connective
tissue elements are not fat-cells, as has been erroneously supposed by Brooks. Their nuclei are
invariably central and not parietal in position, as in fat-cells. These cells are probably very
hygroscopic, as would appear judging from their singular appearance under the microscope. They
appear to be widely distributed in the molluscous invertebrates; they were originally named
“vesicular connective tissue cells” by the histologist Schaefer. An Oyster may in the summer
season absorb water and swell up so as to fill up almost the whole cavity of the shell, and when
opened it may lose so much blood and water in the course of half an hour that it will have shrunk
to one-tenth of its original bulk. This is a common occurrence, and is explained by the prob-
able hygroscopic character of the connective tissue cells and the spongy nature of the whole
mesenchyme which consists of these elements. This also explains why it is that Oysters may be
much swollen in a short time by osmotic action, when immersed in water of a less specific gravity
than the sea-water from which they were first taken. The process has nothing in common with
what might be called fattening, as we shall see hereafter.

There is an apparent atrophy or wasting away of the mesenchyme of the body-mass and
mantle during the spawning season, with a great concomitant development of the reproductive
follicles or tubules. In winter the reproductive follicles atrophy, when the mesenchyme again
increases in bulk in the body-mass and mantle. It also undergoes another remarkable series
of changes corresponding to summer and winter. In summer it acquires an almost glass-like
transparency, so that the mantle, palps, and superficial portions overlying the viscera become

2a

=

= eee

THE INTERNAL STRUCTURE OF THE OYSTER. TAT

translucent. In this condition, if the reproductive glands are undeveloped, the dark mass of
the liver may be seen through the body walls. Towards the autumn, on the other hand, the
connective tissue cells acquire a milky opacity and great solidity as compared with their watery,
transparent condition in summer. This last condition, which involves the whole mantle, the palps
and superficial portions of the visceral mass, indicates to the oysterman the condition of fatness.
The Oysters in this state are plump; do not so readily diminish in bulk when removed from the
Shell as in summer; but that this change is due to storage of fatty matters I have not yet seen any
evidence of any sort which would amount to proof. There is some oily matter in the Oyster, but
not enough to account for the changes which we have described.

The atrophy of the connective tissue during the summer season would appear to indicate that
the material for the genesis of the reproductive elements was derived from the mesenchyme, by a
direct transformation of its substance in which the generative follicles are imbedded. It is, in
fact, the great development of the mesenchymal substance in the autumn and winter, when the
reproductive function is in abeyance, that constitutes the condition of the animal known to oyster-
men as fatness. These relations illustrate very beautifully a well-known physiological principle,
viz, that nutritive processes are very intimately related to the reproductive; they are in fact inter-
dependent.

In summer, when the reproductive organs are gorged with their products, their follicles are
crowded together into contact; in winter, in their atrophied condition, they lie imbedded in the
superficial portion of the mesenchyme of the body-mass, the same as in summer, but are much
less developed, so as to appear in sections like a very open network of strands of very small,
nucleated, incipient embryo cells, the connection of which may be traced into the now collapsed
and internally ciliated branches of the oviducts. AIl the parts of the reproductive apparatus are
therefore present in winter, but in an undeveloped condition. The oviducts branch and spread
over each side of the body-mass just outside of the stratum of reproductive follicles and imme-
diately beneath the mantle. They do not ramify through the substance of the reproductive organ,
but traverse its surface, the follicles emptying their contents into the ducts by way of openings
upon the inner faces of the latter. The main openings of the oviducts of either side open into the
upper branchial cavity on either side of the hinder and ventral portion of the body-mass just
below the muscle. There is but one opening on either side, notwithstanding the various state-
ments to the contrary.

Embryologically considered, the liver is an endodermal structure, a diverticulum of the
stomach. The great bile ducts pass outward from the cavity of the stomach and subdivide again
and again and end blindly in spacious ovoidal hepatic follicles, the simple plicated walls of which
consist of hepatic cells. The function of the liver is in all probability both excretory and secretory,
and takes an all-important share in the processes of digestion. That the function of the liver is
partially excretory is rendered all the more probable from the fact that there is little or no
evidence of the existence of a renal apparatus or organ of Bojanus in the Oyster such as is found
in other mollusks. Dr. Horst looked in vain for a rudiment of this last structure in the embryos
of Ostrea edulis. Transverse sections through those portions of the body where it would most
likely be found, made from both native and foreign examples, exhibit no structure in the least
degree resembling what is regarded as the organ of genes in Unio and Anodonta.

_ The wall of the intestine, like that of the stomach, is ciliated throughout, and is also of endo-
dermal or hypoblastic origin.. Its wall is folded inward along one side in a peculiar way, so that its

Jumen is more or less erescentic in cross-section. This arrangement, together with the very minute

minor folds on its inner surface composed of long, columnar, ciliated epithelial cells, increases the

718 NATURAL HISTORY OF AQUATIC ANIMALS.

amount of absorbing surface very materially. The internal surface of the stomach is also very —
much plicated; but here the folds are both large and conspicuous, with small folds often inter- |
vening. There are neither annular nor longitudinal muscular fibers in the wall of the intestine ;
the sole motive force used in the propulsion of the ingested food appears to be exerted by the
ciliary covering which everywhere clothes the internal surface of the alimentary tract from the
mouth to the anus.

It would appear that the intestine makes two complete bends upon itself at a very early stage
of embryonic life, according to the observations of Horst, long before it measures a ninetieth of
an inch in diameter. The development of the liver seems to be at first lateral and somewhat
ventral; an arrangement traces of which may still be noticed in cross-sections of the adult.

The course of the intestine in the adult may be described as follows:

The mouth is a wide opening between the upper median angles of the palpi; so wide, indeed,
that the animal can searcely be said to have an w@sophagus; immediately follows the stomach,
which is seen to have very pronounced folds internally, with a generally transverse direction, but
two of these, which lie in a somewhat ventral position, area pair of inward-projecting folds which
are themselves plicated. The intestine then follows an oblique course, downward and backward,
when it makes a sharp bend returning beneath the floor of the pericardial space, passing obliquely
upward and forward, somewhat to the right and dorsal of the stomach, when it crosses exactly
over the mouth or very short gullet, passing downward to the left side of the animal, alongside
and a little to the lower side of the stomach, when it again turns upward and passes over the
pericardial space to end in the rectum just over the middle of the adductor muscle. The clusters of
hepatic lobules or follicles dip down into the folds of the walls of the stomach, but the liver does not
follow the course of the intestine proper, which is provided internally with a curious pair of longi-
tudinal and parallel folds, which project into the intestinal cavity and extend from the pyloric end
to very near the anus. The presence of these folds gives to the fecal matters their singular appear-
ance, which are not in the form of a cylinder as they leave the vent, but in the form of a tube with a
part of one side removed. Tracing the course of the intestine by sections is not the proper way;
they can be very easily dissected out for their entire length by means of the scissors and forceps.

The systemic heart of the Oyster is that organ which serves to propel and redistribute the
colorless blood of the animal through the body for its nourishment, and through the gills that the
blood itself may discharge into the water the poisonous gases with which it is loaded in passing
through the body, and receive a fresh supply of oxygen as fresh supplies of water pass through
the gills. The heart consists of three principal chambers; the upper, largest, whitish and partially
divided by a median septum or partition, is the ventricle, and the two lowermost and smaller,
brownish paired chambers are known as the auricles. These three chambers which comprise the
heart of the Oyster lie in a crescent-shaped space, the pericardial space, just forward of the
adductor muscle. The ventricle is almost globular; its walls are made up of a delicate meshwork
of unstriped muscular fibers, which are so interlaced as to be altogether untraceable. From the
ventricle a great posterior and an anterior aortic vessel arises. These two vessels distribute the
blood to the posterior and anterior portions of the body of the animal, but soon divide into paired
vessels which traverse the mantle on either side both anteriorly and posteriorly, while one great
median branch passes forward over the stomach. The blood is really distributed soon after
leaving the main vessels, especially in the body through the spongy connective tissue spaces, as
already described, and is collected into a great ventral canal from which a large part of it passes
into the gills. From the four gills or branchial pouches the blood flows back to the ventricles

id

SEX OF THE AMERICAN AND BUROPEAN OYSTERS. 719

through six great branchiocardiac vessels, three of which are arranged on each side; two pairs of
these are anterior in position and one pair posterior.

The circulation of the Oyster is quite different in character from that observed in a vertebrated
animal. In the latter the heart pumps the purified blood to and through the gills before it passes
to all parts of the body; in the Oyster, on the other hand, the fresh, pure blood is pumped by the
heart from the gills before it passes to all parts of the body.

A curious and interesting point which I think it desirable to mention, because I have not
noticed that attention has hitherto been especially called to it, is the metamorphosis of the larval
Oyster into the adult. A. de Quatrefages' has alluded to it, but not in explicit terms. I have
shown in my sketch on the growth of the animal that the larval shell was quite different from that
of the adult, in fact, more like a very diminutive pisidiwm than anything else. The metamorphosis
of the larval shell, or rather its passage into that of the spat, is abrupt. Not so with the soft parts;
the oldest larvee yet studied by any competent biologist show that the mouth of the larva is
placed on the ventral side of the embryo, and that the hinge is situated on almost exactly the
dorsal or opposite side. The ventral position of the mouth of the larve and its anterior or cephalic
position in the adult show that a very important series of changes in the position of the viscera
must take place between the time when the larva loses its principal embryonic features and
acquires the adult arrangement and relations of its hard and soft parts. In other words, we are
made aware, after instituting the foregoing comparison, that the Oyster actually undergoes a
metamorphosis.

If an Oyster be carefully opened it will be found that the animal adheres to the shell at four
points, or at two points on either valve. The principal points of attachment are of course the
insertions of the great compound adductor muscle, made up of two portions which may be
distinguished by the color of the cut ends of the component fibers. The great shield-shaped
purple areas on either valve mark the points of insertion of the great adductor in the American
Oyster, and also in the Portuguese form, which resembles it considerably. In Ostrea edulis, or the
European species, the insertion of the adductor muscle is very rarely colored, so rarely indeed that
we may regard this feature as one of the specific marks of this form. But in both the American
and the European species there is a second muscular attachment, as implied above, which appears
to have been very generally overlooked. It is situated nearer to the hinge than to the great
adductor, and is sometimes marked by a slight depression not over an eighth of an ineh in its
greatest transverse diameter. It gives attachment to a feeble muscular bundle which springs out
of the mantle on either side of the visceral mass, and when the animal is torn loose a slight
whitish scar on the soft part marks its position on the surface of the mantle. I have been
informed that Mr. W. H. Dall, who has investigated the matter, has identified this muscle with
the pedal muscle of some other acephalous mollusks.

212. SEX, SEXUAL PRODUCTS, AND DIFFERENCE OF THE SEXUAL HABITS OF THE
AMERICAN AND EUROPEAN OYSTERS.

“The number of male cells which a single male will yield is great beyond all power of
expression, but the number of eggs which an average female will furnish may be estimated with
sufficient exactness. A single ripe egg measures about one five-hundredth of an inch in diameter,
or five hundred laid in a row, touching each other, would make one inch; and a square inch would
contain five hundred such rows, or 500 x 500=250,000 eggs. Nearly all the eggs of a perfectly

'Metamorphoses of Man and the Lower Animals. Translated by H. Lawson, M. D., pp. 104-109. London, 1864.

720 NATURAL HISTORY OF AQUATIC ANIMALS.

ripe female may be washed out of the ovary into a beaker of sea-water, and, as they are heavier
than the sea-water, they soon sink to the bottom, and the eggs of a medium-sized female will
cover the bottom of a beaker two inches in diameter with a layer of eggs one-twentieth of an inch
deep. The area of the bottom of a beaker two inches in diameter is little more than three square
inches, and a layer of eggs one-twentieth of an inch deep, covering three square inches, is equal to
one three-twentieths of an inch deep and two square, and as a single layer of eggs is one five-
hundredth of an inch thick, a layer three-twentieths of an inch thick will contain seventy-five
layers of eggs, with 250,000 eggs in each layer, or 18,750,000 eggs. It is difficult to get the eggs
perfectly pure, and if we allow one-half for foreign matter and errors of measurement, and for
imperfect contact between the eggs, we shall have more than nine millions as the number of eggs
laid by an Oyster of average size, a number which is probably less than the true number.

“Mobius estimates the number of eggs laid by an average European Oyster at 1,012,925, or only
one-ninth the number laid by an ordinary American Oyster; but the American Oyster is very much
larger than the European, while its eggs are less than one-third as large; so the want of agreement
between these estimates does not indicate that either of them is correct.! Another estimate of
the number of eggs laid by the European Oyster is given by Eyton (‘ History of the Oyster and
Oyster Fisheries,’ by T. C. Eyton, London, 1858). He says, p. 24, that there are about 1,800,000,
and therefore agrees pretty closely with Mébius.

“ An unusually large American Oyster will yield nearly a cubic inch of eggs, and if these were
all in absolute contact with each other, and there were no portions of the ovaries or other organs
mixed with them, the cubic inch would contain 500%, or 125,000,000. Dividing this, as before, by
two, to allow for foreign matter, interspaces, and errors of measurement, we have about 60,000,000
as the possible number of eggs from a single Oyster.

“Although each male contains enough fluid to fertilize the eggs of several females, there does
not seem to be much difference in the number of individuals of the two sexes. When a dozen
Oysters are opened and examined, there may be five or six ripe females and no males, but in
another case a dozen Oysters may furnish several ripe males but no females, and in the long run
the sexes seem to be about equally numerous. Oystermen believe that the male may be dis-
tinguished from the female by certain characteristics, such as the presence of black pigment
in the mantle, but microscopic examination shows that these marks have no such meaning, and
that there are no differences between the sexes except the microscopic ones. It is not necessary
to use the microscope in every case, however, for a little experience will enable a sharp observer
to recognize a ripe female without the microscope. If a little of the milky fluid from the ovary of
a female with ripe or nearly ripe eggs be taken upon the point of a clean, bright knife-blade and
allowed to flow over it in a thin film, a sharp eye can barely detect the eggs as white dots, while
the male fluid appears perfectly homogeneous under the same circumstances, as do the contents of
the ovary of an immature female, or one which has finished spawning. When the eggs are mixed
with a drop of water they can be diffused through it without difficulty, while the male fluid is
more adhesive and difficult to mix with the water. By these indications I was able in nearly
every case to judge of the sex of the Oyster before | had made use of the microscope. ?

“During my investigations I submitted more than a thousand Oysters to microscopic
examination. My studies were carried on during the breeding season, and I did not find a single

'MObius’ measurement, from .15 to .18 millimeter, is given (Austern und Austernwirthschaft, 1877) as the diameter,
not of the egg, but of the embryo, but his figures show that the European Oyster, like the American, does not grow much
during the early stages of development, but remains of about the same size as the egg.

2W. K. BROOKS: op. cit., pp. 13-15.

THE CELL-STRUCTURE. OF THE OYSTER. 721

“a

hermaphrodite. The male cells are so small compared with the eggs that it would be impossible
to state that a mass of eggs taken from the ovary contained no spermatozoa, although they could
not escape detection if they were at all abundant.

“On the other hand, a single egg in the field of the microscope, in a drop of male fluid, would
be very conspicuous and could not escape detection; and the fact that not a single case of this
kind occurred is sufficient to establish the distinctness of the sexes at the breeding season.”!

Writing about this matter in 1880, I said: ““No evidence to show that our Oyster is her-
maphrodite was found during the entire season; nor were my searches for embryo or eggs in
the mantle or in the gills more successful than those carried on two years before by Professor
Brooks. There is no doubt whatever that the Oyster of Europe nurses its young in its mantle
or gills for some time; nor can we well question the very high authority of Mébius for saying
that in most cases the sexes are separate, and that only one kind of products, viz, either eggs or
spermatozoa, are at any time found in the generative organs. Lacaze-Duthier’s observations seem
to confirm the conclusions of Mébius.”

In reference to the structure of the cells which make up the body of the Oyster, as well as
regarding the eggs, Dr. Brooks, on page 19 of his essay, writes as follows:

“Bach of these consists of a layer of protoplasm around a central nucleus, which, in the egg,
is a large, circular, transparent body known as the germinative vesicle. Each cell of the body is
able to absorb food, to grow and to multiply by division, and thus to contribute to the growth of
the organ of which it forms a part. The ovarian eggs are simply the cells of an organ of the body,
the ovary, and they differ from the ordinary cells only in being much larger and more distinct
from each other ; and they have the power, when detached from the body, of growing and dividing
up into cells, which shall shape themselves into a new organism like that from whose body the
egg came. Most of the steps in this wonderful process may be watched under the microscope,
and owing to the ease with which the eggs of the Oyster may be obtained, this is a very good egg
to study.”

| Brooks has represented the freshly laid ova of the Oyster with a spherical nucleus and

‘nucleolus ; the former is large and clear, and is imbedded near the center of the egg, and inside of
it the nucleolus is lodged somewhat to one side. I do not find the latter spherical, as described,
but formed as if composed of a larger and smaller highly refringent pair of spheres, partly fused
with each other, or of the same form as the nucleoli of the eggs of Anodonta as described by
Flemming.

Some investigations conducted under the auspices of the Dutch Government indicate that the
structure of the generative organs of the European Oyster is not, as has been supposed, strictly
follicular, but that they may rather be regarded as a mass of anastomosing tubes of irregular caliber.
The complete proof of this has been developed by the writer in the course of investigations carried
‘out upon our native Oysters, in which the generative organs wcre very immature during the

inter season. Both Brooks and myself have spoken of the generative follicles as though they
had been clearly made out; it now appears that we will be compelled to modify our terminology
ewhat, in the face of the fact that I have sections of the immature generative organ which
hibit it as a network of germinal cells, as well as sections of the mature organs which show a

Vertically to the surface of the visceral mass. This arrangement reminds one somewhat of the
i r
ee lW. KX. BROOKS: op. cit., p. 35.

}

oe, NATURAL HISTORY OF AQUATIC ANIMALS.

wore or less parallel disposition of the seminal tubules of the testicles or milt of fishes and higher
animals.

In microscopical cross-sections of the adult Oyster, whether it be male or female, the repro-
ductive glands are found to be composed of a great number of minute pouches or follicles. In the
eross arrangement of the follicles no difference between the sexes is discernible when thin sections
are scrutinized with the microscope. Upon making an examination of the contents of the follicles
with the microscope a great difference at once becomes manifest; in the male the spermatic
particles in the follicles appear very finely granular, and if mature the tails or flagella of the
spermatic particles tend to be directed toward the outlet of the follicle; in the female, sections of
the follicles show the eggs in various stages of development attached by their narrow extremity
to the walls of the reproductive saceules. The egg is pyriform in shape while still in the ovary,
but the stalk is not as long as in the eggs of Scrobicularia, as described by von Jhering. As
elsewhere stated, the oyster-egg is not globular when first extruded. It will be readily understood
that the sexes may be very readily distinguished by these and other marks observed in sections.
The immature ova are vastly larger than the spermatozoa, which measure under the ten-thousandth
of an inch at their largest end. The head of the spermatozoén of both the American and European
Oyster is globular; that of the spermatozoén of the Soft Clam (Mya) is ovoidal in form. The tail
or flagellum of the spermatic particle is the locomotive organ which lashes back and forth very
rapidly and propels it through the water and finally brings it into contact with the egg.

213. NEW METHODS OF DISTINGUISHING THE SEXES AND OF TAKING THE EGGS OF
THE OYSTER. !

DISCRIMINATION OF THE SEXES.—One of the first requisites of a practical system of arti-
ficial fertilization of the eggs of the Oyster is a means which, in the hands of unskilled persons,
will enable them, without the aid of a microscope, to infallibly distinguish the sexes apart. Such
a means we now propose to describe. Having tested it practically, and found it possible to
instruct persons of ordinary intelligence in a few minutes, we have no hesitation in offering an
account of the method so as to make it more generally available in the hands of those who may
be interested in this subject.

It is premised that the spawn is squeezed from the reproductive glands by the method to be
described further on. As soon as the spawn is emitted from the generative opening in consequence
of the pressure exerted upon the gland and the ramifications of its ducts, it is drawn up by means
of a small pipette or medicine dropper, provided with a small collapsible bulb at the upper end
which is held between the thumb and forefinger. Pressing the bulb between the fingers, then
immersing the open end of the pipette into the extruded spawn, and then allowing the bulb to
expand by its own elasticity, it will draw or suck up the spawn which has been pressed out very
neatly; and if one is careful, absolutely nothing but the spawn is picked up. One soon becomes
very expert in the use of the pipette.

The next requisite is a shallow glass dish, or even a plain tumbler will answer, into which
say a half gill of clean sea-water has been poured. Taking up the extruded spawn from the
opening of the duct it is dropped from the pipette into the clear water. This last simple operation
enables us to tell without fail te which sex the products belong. If the creamy white mass consists
of eggs which have been pressed from the generative openings and is dropped into the water, it will

at once break up into a granular cloud as the spawn strikes the latter, the granules themselves

'The observations and experiments discussed in this article were conducted at Saint Jerome’s Creek during the
months of July and August, 1882. :

ARTIFICIAL BREEDING OF OYSTERS. 53

being very distinctly visible, especially if the glass vessel be resting upon a dark ground so as to
bring the whitish granules into relief. The granules are nothing more than the ova or eggs of the
Oyster, and at once indicate that the individual from which they were obtained is a female. In
case the products are male, they break up as they mingle with the water into a milky white cloud
in which no granules are visible to the naked eye. It is also very important fo observe that as the
milt is stirred in the water it breaks up at first into long, fleeey white clouds which resemble very
Strikingly in miniature what are known to meteorologists as cirrus clouds, or, vulgarly, “mare’s
tails,” reminding one of these in the way in which the fine particles of milt give rise to streaks,
wisps, and fibers as it breaks up in the water, without giving rise to any visible granular appear-
ance as occurs in the case of the female products, but to an opalescent or milky aspect. These
distinctions, once learned, are so palpable that the novice may as infallibly discriminate the sexes
of the Oyster apart by their aid as can be done by the most skilled biologist with a powerful
microscope.

THE IMPREGNATION OF THE EGGS.—The method formerly used was to first learn the sex of
a number of adult Oysters with the microscope, then cut out the generative glands with their
products and chop up those of different sexes separately in small dishes with sea-water. This
system we may now say is barbarous, because it is crude; large numbers of eggs are destroyed
by crushing, or are injured by the rough usage to which they are subjected, and, besides, there is
no assurance that the eggs or milt operated with are quite mature. It is also troublesome to free
the generative gland from fragments of the liver which help to pollute the water in the incubating
vessels with putrescible organic matter, and thus interfere greatly with the life and healthy devel-
opment of the embryos.

By our method the objectionable features of the old plan, as stated above, are overcome. If
possible, select good-sized Oysters; open them with the greatest possible care so as not to mutilate
the mantle and soft parts. Carefully insert an oyster-knife between the edges of the valves and
cut the great adductor muscle as close as possible to the valve which you intend to remove,

leaving the animal attached to the other valve, which, if possible, should be the left or deepest one.

‘The soft parts being firmly fixed or held fast by the great adductor muscle to the left valve
prevents the animal from slipping under the end of the pipette, held flatwise, as it is gently and
firmly stroked over the generative gland and ducts to force out the generative products.

To prepare the animals to take the spawn from them, after opening, the following precautions
are to be observed: Note that the reproductive gland in great part envelopes the visceral mass,
and extends from the heart space, just in front of the great adductor, to within a half inch or so of
the head or mouth end of the animal, which lies next to the hinge. Note also that both sides of

the visceral mass which incloses the stomach, liver, and intestine are enveloped on either side by
-amembrane which also lies just next the shell and is garnished by a fringe of purplish; sensitive
“tentacles along its entire border except at the head end where tic mantle of the left side passes
into and is continuous with that of the right side of the animal. The ventral or lowermost side of
| the animal, anatomically speaking, is marked by the four closely corrugated gill plates or pouches,
which are preceded in front by the four palps or lips, but both the gills and palps depend
downward between the lower borders of the mantle of the right and left sides. Note, too, that
if the mantle is carefully cut and thrown back on the exposed side of the animal between the
Pp per edges of the gills and the lower edge of the cut or exposed end of the great adductor
muscle, the lower and hinder blunted end of the visceral mass will be exposed to view. It is on
either side of this blunted end of the visceral mass between the upper edge of the gills and lower
side of the great muscle that the reproductive glands open almost exactly below the great adductor.

724 NATURAL HISTORY OF AQUATIC ANIMALS,

From these openings we will afterwards find, if the animal is sexually mature and the operation ts
properly conducted, that the spawn will be forced out in a vermicular, creamy white stream. But
in order to fully expose the reproductive organ we should carefully continue to sever the mantle
of one side with a sharp penknife or small scissors, some distance forward of the great muscle
towards the head, cutting through the mantle just above the upper borders of the gills and following
a cavity which lies between the latter and the lower border of the visceral mass. A little
experience will teach one how far it is necessary to carry this incision of the mantle. For some
distance in front of the heart space the mantle is free or detached from the visceral mass and
reproductive organ which lies immediately beneath, and this enables one, if the last described
incision has been properly made, to almost completely expose the one side of the visceral mass
and the richly tinted, yellowish-white reproductive gland which constitutes its superficial portion.
The opening of the gland and its superficial ramifying ducts being laid bare on the exposed side
uf the animal we are ready to press out the spawn on that side. Before beginning this, however,
it is important to observe that the principal duct passes down just along the edge of the visceral
inass where the latter bounds the heart space, in which the heart may be observed to slowly
pulsate, and that this great duct ends somewhere on the surface of the ventral blunted end of the
visceral mass. To expose the great or main generative duct it may be necessary to cut through
or remove the pericardial membrane which incloses or covers the heart space on the exposed side.
If the Oyster is sexually mature, the main duct will be observed to be distended with spawn, and
that, originating from it and branching out over almost the entire surface of the visceral mass,
there are minor ducts given off, which again and again subdivide. If these are noted, and it is
observed that they are engorged, giving them the appearance of « simple series of much branched
great veins filled with creamy white contents, it may be certainly presumed that your specimen is
mature and that spawn may be readily pressed from it.

The operation of pressing the spawn out of the ducts requires care. The side of the end of the
pipette may be used, being careful not to crush or break open the ducts as you gently and firmly
stroke the pipette flatwise over the side of the visceral mass backward from the hinge towards
the heart space and over the great duct at the border of the latter diagonally downward and
backward to the opening of the reproductive organ. If this has been properly done it will be
found that the generative products are being pushed forward by the pipette through the ducts,
as the pressure will be seen to distend the latter, the contents of the branches flowing into the
larger and larger trunks until they are forced outward through the main duct and opening below
the great adductor, where they will pour out in a stream one-sixteenth of an inch or more in diameter
if the products are perfectly ripe. The sexes may be discriminated as described at the outset, and
it is well to first find a male by the method already given and proceed to express the milt as
described above into say a gill of sea-water, adding pipetteful after pipetteful until it acquires a
milky or opalescent white color. As the milt or eggs are pressed out of the opening of the duets
they are to be sucked up by the pipette and dropped into the water, the mixture of milt being first
prepared, to which the eggs may be added as they are expressed from the females. The judgment
of the operator is to be used in mixing the liquids; in practice I find that one male will supply
enough milt to fertilize the eggs obtained from three or four females, and it does not matter if the
operation takes from twenty to thirty minutes’ time, as the male fluid, which it is best to prepare
first, will retain its vitality for that period.

It is always desirable to be as careful as possible not to get fragments of other tissues mixed
with the eggs and milt, and the admixture of dirt of any kind is to be avoided. ‘To separate

RATE OF GROWTH OF OSTREA VIRGINICA. 729

any such fragments nicely, I find a small strainer of coarse bolting or cheese cloth to be very
convenient.

In the foregoing description we have described the method of obtaining the spawn only from

the side of the animal exposed in opening the shell. A little experience will enable one to lift up
the head end of the animal and throw it back over the great adductor muscle, expose the opening
of the reproductive organ on the left side, or whatever the case may be, and also express the
spawn from that side, thus as effectually obtaining all of the ripe eggs or milt as is possible in the
process of taking the same from fishes.

[t is remarkable to note the success attending this method, since almost every egg is perfect
and uninjured, the percentage of ova which are impregnated is much larger than by the old
method, reaching, I should say, quite ninety per cent. of all that are taken when the products are
perfectly ripe. It is also found that the products are not so readily removed by my process if they
are not pertectly mature, which is also to a certain extent a safeguard against getting poor or
immature spawn. In the course of an hour after the products of the two sexes have been mingled
together it will be found that nearly every egg has assumed a globular form, has extruded a polar
cell, lost the distinct. germinative vesicle and spot in the center, and begun to develop.

It is noteworthy that our practice as herein described has completely vindicated the state-
ment made by the distinguished French anatomist and embryologist, M. Lacaze-Duthiers, that
there is but a single generative opening on each side of the visceral mass of the Oyster, and that,
as we have stated, it is found to open just below the great adductor muscle.

We have also discovered, since the foregoing was written, that the use of an excessive amount
of milt is of no advantage. The water in which the eggs are to be impregnated only requires to
be rendered slightly milky; a very few drops of good milt is sufficient to make the impregnation
a success. Too much milt causes the eggs to be covered by too large a number of spermatozoa ;
thousands more than are required if too much is used. These superfluous spermatozoa simply
become the cause of a putrescent action which is injurious to the healthy development of the eggs. ;
A drop of milt to twenty drops of eggs is quite sufficient.

Immediately after the ova have been fertilized it is best to put them into clean sea-water at
once, using water of the same density as that in which the adults grew. If the attempt is made
to impregnate the eggs in water much denser than that in which the adults lived, it is probable
that the milt will be killed at once. This singular fact, which was accidentally discovered by
Colonel McDonald and myself, shows how very careful we should be to take into consideration
every variation in the conditions affecting a biological experiment. If sufficient water is used no
trouble will be experienced from the pollution of the water by dangerous micro-organisms which
are able to destroy the oyster embryos. From fifty to two hundred volumes of fresh, clean water

-inay be added to the volume in which the eggs were first fertilized. This may be added gradually
during the first twenty-four hours, so as to assist aération and prevent the suffocation of the
embryos.

214. RATE OF GROWTH OF OSTREA VIRGINICA.

SIZE OF THE EGG.—The egg of the American Oyster, according to Brooks, is approximately
soo Inch, being very nearly perfectly spherical after the extrusion of the polar or direction cells
(Richtungsbldschen of the German embryologists). This accords with what the writer has observed

‘Mm our species, and in the Portuguese Oyster, probably O. angulata Lam., the size of the egg
‘appears to be about the same, judging from specimens of the latter examined by me in March

last. Judging from the figures and the stated amplifications given in the papers of M. Davaine,

726 NATURAL HISTORY OF AQUATIC ANIMALS.

the egg of Ostrea edulis is ;45 inch in diameter. Estimates based on the figures of M. Lacaze-
Duthiers give dimensions of ;1, inch. These discrepancies I think are probably too great, and
may be due to imperfect micrometric methods. If they are real it would indicate a specific
difference of some importance between O. edulis and O. virginica.

The actual volume of the egg of the American Oyster would accordingly be a little more
than ssgohoo00 Cubic inch, a solid so minute that we are unable to frame any adequate con-
ception of its diminutiveness. Under the best conditions, as seen against a dark back-ground,
it is visible as a grayish-white speck ; almost an optical point. It is from this diminutive spherical
mass of living matter that the young Oyster is developed. The development of the embryo
proceeds, as far as I can make out, according to the accounts given by Davaine, Brooks, Horst,
and others, similarly to that of other lamellibranebs. To Hatschek! we are indebted forthe most
secure foundation for our future embryological investigations upon this difficult group of mollusks;
and we must not forget to mention the very important researches of Ray Lankester (Phil. Trans.,
1875), principally upon Pisidium. Ihave not been able to observe the development of the larval
Oyster beyond the size attained by it after the complete segmentation of the egg, the develop-
ment of the shell, the velum, and alimentary tract. In fact, no embryos which I have attempted
to rear from artificially impregnated eggs have ever lived long after the time when they began
to take food, which is immediately after they acquire the velum, permanent mouth, and vent,
and are almost or altogether covered on either side by the very symmetrical larval shells, which
consist of carbonate of lime laid down in a matrix of conchioline. The isolation of the conchioline
is readily effected by the use of acetic acid, the acid dissolving out the lime entirely. I find
that Brooks and Dr. Horst? have tried a similar experiment with similar resuits. The latter
writer has also been able to watch the development of the naturally impregnated ova of Ostrea
edulis until a pretty advanced stage was reached. He disagrees with Brooks in his interpretation
of the gastrula stage, and thinks that the invagination regarded by the American investigator
as the blastopore must be considered to represent simply the first rudiment of the shell-gland.
In assuming this position, from what I have been able to gather in the course of ny own investi-
gation of the development of the American species, [ think we are bound to accept Dr. Horst’s
determination of the homology of the shell-gland of the Oyster with that of other lamellibran-
chiate and cephalophorous mollusks.

EARLY STAGES OF DEVELOPMENT.—The oral invagination, according to Dr. Horst, originates
on the opposite or ventral side of the embryo and has no connection with the dorsal pallial
invagination or shell-gland. The early stages of the American and European species, like the
later ones, appear to present no marked differences, except that the latter appears, on the evidence
of Dr. Horst, Mébius, and others, to carry the ova and embryo in the mantle cavity, from which
the first-named author obtained his material for study, by breaking a hole through the shell near
the margin, so as to enable him to introduce a pipette into the’ pallial chamber. This method of
getting embryos is impossible in our native species, which has wholly different breeding habits, as
is proved by the investigations of Brooks, Winslow, Rice, and myself. How much further than
heretofore Messrs. Brooks and Winslow have been enabled to carry the development of our native
Oyster during the past season at Beaufort, North Carolina, I have not been able to learn, nor do I
know anything more definitely as to how much success has been attained in the artificial produe-
tion of Ostrea edulis from artificially-impregnated eggs at the hands of Mr. Littlewood, of England,

'Ucber Entwickelungsgeschichte von Teredo. Arbeiten aus dem Zool. Inst. Wien., Bd. iii.
* Bijdrage tot de Kennis van de Ontwikkelingsgeschiedenis van de Oester (Ostrea edulis L.), door Dr. R. Horst. Tijdschr.
d. Ned. Dierk. Vereen, Deel, vi, 1882.

LARVAL OYSTERS. CPU

who has claimed that he had succeeded in rearing them to the age of five months, specimens of
which it is said were shown at the Fishery Exhibition recently held in Ndinburgh.

EXPERIMENTS AT SAINT JEROME’S CREEK.—Our experiments made at Saint Jerome’s Creek
during the past summer gave the most contradictory results, and the interval of development
between that of our oldest embryo with its diminutive Pisidium-like valves measuring about <4
inch in diameter, and that of the embryo when its valves first begin to lose their embryonic form,
still remains unbridged. The dimensions of the embryo or “fry,” as we may more properly call it
when it becomes fixed, are between = and ;4 inch according as the measurement is made longi-
tudinally or transversely. The difference in magnitude between the oldest artificially incubated
fry seen by me and that of the youngest fixed embryos which I collected is very small, amounting
only to ;4+> inch, or a little more than ;j5 inch. To determine the relative volumes of these
stages, and consequently’ the amount of food which has been taken in and converted into the
structure of the more advanced stage in addition to the original bulk of the egg, we need only
take the cubes of their respective diameters and compare them. Taking the diameter of the egg,
or => inch, as the diameter of the most advanced embryo seen by me, which we will consider
unity, and comparing it with {4 inch, or the transverse diameter of the newly fixed fry, we find,
after having reduced the last quantity to its simplest form as compared with 1, or the diameter of
the egg, that we have 5.1+. The diameters then of the first and last embryonic or truly larval
stages are to each other as 1 is to 5.1+, and consequently their volumes will be to each other as
the cubes of these numbers, or as 1 is to 132.651+. The difference between these two quantities,
or 131.651+ times 1, will give us approximately the amount of food material which has been taken
up by the embryo in passing from the condition when it was first able to feed until it fixed itself,
showing that the process of growth has been going on vigorously in order to augment the volume
of the young creature at the enormous rate indicated by our figures. We have, however, been
dealing not with absolute but with relative or compared volumes only; if the egg contains
ssoosuoes Cubic inch of protoplasmic matter approximately, the newly-fixed fry, which we will
assume to be globular, and contains, as shown above, over 132 times as much material, the

absolute bulk of the latter will be gsootos00 Cubic inch multiplied by 132, or s5p322550 cubic

inch, which, in its simplest form, is therefore ;gsyo7_¢ Cubic inch, or the absolute volume of the
newly fixed fry. Ninety cubed, or 729,000 young Oysters could therefore be contained in a cubic
inch of space, if taken at the stage at which they begin to be transformed into spat. This large
number is, of course, small when compared with 125,000,000, the number of eggs which might be
contained by the same extent of space.

THE LARVAL CHARACTER OF THE YOUNG OYSTER.—The proof of cine larval character of
the youngest fixed stage of the Oyster rests upon the three following well-ascertained facts:
“Ist. The perfect symmetry and great convexity of the valves; 2d. The entirely different shape
of the shell as compared with those of.the spat and adult; 3d. Its wholly different micro-
“scopic structure when compared with the later and full-grown stages. The form of the shell, at
the time the animal is about to begin to develop the spat shell, is suborbicular, very thin, ven-

; tricose, resembling in many respects the shell of Cyclas or Pisidiwm, having the symmetry of
_ those genera, with umbones of about the same form and prominence. These features mark the
larval shell of the Oyster so unmistakably that its valves may always be very readily recognized
the tips of the valves of spat under a year old. The larval valves lie on the tips of the valves

of the spat like small hemispherical caps, but can usually not be found after the young Oyster
enters upon its second year, as its umbones, together with the larval shells which surmount them,

728 NATURAL HISTORY OF AQUATIC ANIMALS.

have been eroded ‘by the action of the carbonic dioxide in solution in the sea-water. The
presence of the larval shells in an unimpaired condition on the umbones of the valves of Oysters
is therefore an indication that such specimens are young, probably under a year old.

The third character, alluded to above, which distinguishes the larval shell of the Oyster is
the perfect homogeneity of the calcareous matter. Unlike the valves of the spat or translucid
flakes from the shell of the adult, they exhibit no prismatic arrangement of the calcic carbonate
in a matrix of conchioline. In the valves of the adult and spat, on the other hand, the calcic
carbonate tends to assume a prismatic arrangement vertical or at right angles to the plane of
the length and breadth of the shell. This distinction is so marked that in very young individuals
which have only lately become fixed one may very readily determine with the aid of the micro-
scope the line of demarkation along which the formation of the larval shell ceased and where the
prismatic calcareous structure of the valves of the spat began to be developed.

CHARACTERS OF THE LARVAL SHELL.—The only characters of structure which the larval
shell has in common with that of the spat and adult are the lines of growth visible in all three.
This shows that the valves grow in extent at all stages by the addition of lime to the edges of
the valves, each layer of mineral matter and organic matrix extending over successively greater
and greater areas, as in the growth of the shells of mollusks in general, the umbones being
the points from which the valves grow in an eccentric manner in consequence of the gradually
increasing extent of the mantle—the shell-secreting organ—as the growth of the animal
proceeds. Having clearly defined the nature of the larval shell of the Oyster, up to the time
when it is ready to begin to build or secrete the shell of the spat, we may next discuss the
character of the transition from the one to the other.

The transition is apparently an abrupt one. The excessive convexity of the valves of the fry
contrast strongly with the almost flat lower valve and feebly convex upper one of the spat. At
the free edges of the larval shells where they pass directly into the structure of the valves of the
spat there is a marked offset or angle marking very distinctly the difference of convexity between
the two stages of shell development.

oop OF THE YOUNG OysTER.—As already remarked, I have seen food in the intestine
of the young Oyster on the second day of development, but how long it may take before the
young embryo of this stage of growth shall have taken and appropriated one hundred and
thirty-two times its own volume of food material, I am not able to say. This it must do
before it can have attained to the size of the larva which is transformed into spat. The food
is propelled through the alimentary canal by the action of innumerable vibratory filaments
which clothe the inside of the throat, stomach, and intestine as in the adult; the intestine,
stomach, and liver are not, however, as complex as in the full-grown animal.

Of the method of fixation I have as yet learned nothing of value. That this is accomplished
by some sort of byssus 1 have no doubt. The faet that it is the left valve which is always the
lowermost and attached one would indicate that the method of fixation was not capricious or
haphazard in its nature.

I would infer from what we learn from the study of other animals that it may require quite a
week before an embryo reaches the dimensions of one-eightieth of an ineh, but we have no data
upon which to base any conclusions of value. Of the later stage of development we know some-
thing detinitely. The main fact which we have so far decided is the size of the larval shell.

RaTkE OF GROWTH.—After fixation the growth of spat is very rapid, as may be inferred
from the fact that I have found spat upon collectors which had not been placed in position

FOOD OF THE OYSTER. 129

more than a week to ten days, upon which I detected spat one-fourth of an inch across. In
other cases the following were the observed dimensions: On a collector which had been placed
near a bed of spawning Oysters for twenty days I obtained a specimen of spat seven-sixteenths
of an inch across; from another collector immersed for forty-four days I obtained specimens
thirteen-sixteenths of an inch in diameter; from another out forty-eight days a specimen
measuring about one inch. Another set of collectors which had been out for seventy-nine days
had spat attached which measured one and three-fourths inches across. Some still larger spat
collected by me was not over eighty-two days old, and measured nearly two inches in length
from the hinge to the distal margin of the valves. Still larger specimens have been observed
by the writer, which bore every evidence of having affixed themselves during the same
season.

If we contrast the above measurements with those given by Mobius of the spat of O. edulis
of known age, I conclude that the American Oyster grows three or four times as rapidly as the
former. For instance, Mobius figures a European Oyster twelve to fifteen months old, which
measures only one and one-fourth inches in diameter. Contrasting this with the size of the
American at seventy-nine to eighty-two days old, and measuring from one and three-fourths to
nearly two inches in diameter, we see how greatly our species surpasses that of Europe in vigor
and rapidity of growth.

Of the rate of growth beyond the ages given above I have only a few data, based on the spat
which was caught on collectors put out in Saint Jerome’s Creek in July and August, 1880. In the
following autumn the collectors which had been put out into the creek were taken up and the spat
removed from them. This was then put into a box, through whieh the water could circulate
freely, and put back into the creek, in order that we might be enabled to learn how much growth
these young Oysters would make during the winter and next season. I did not have an opportu-
nity to examine them, however, until the 10th of July, 1882. From the time of their fixation in
July and August, 1880, to the time when I made my last examination of these specimens, a
period of about twenty-three months had accordingly elapsed. One of the largest specimens
examined by me measured three and three-eighths inches in length and two and five-cighths
inches in width. Another smaller specimen measured two and a half inches long and two
and a quarter inches in width. They were about the size of Oysters available for planting, and I
have no doubt that in the course of two or three years more, if placed under favorable conditions,
they would reach a marketable size. The inference, therefore, is that it takes at least four to five
years for an Oyster to grow large enough, starting from the egg, to be available for market.

In order that an Oyster may grow to attain the great size of certain single individuals which
I have seen, it may take even ten years. I should think it would take at least that length of time
for an Oyster to grow until 1ts valves would measure nine inches in length, a few of which I have
seen of this enormous size. These, it must be remembered, were not ‘Raccoon Oysters” or “‘Cat’s-

_ tongues,” as the narrow, elongate individuals are called which grow so densely crowded together
upon the banks as to be abnormally lengthened. Under favorable conditions, | do not think
“it improbable that an Oyster may live to the age of twenty years, attaining corresponding
dimensions.

\y

i . 215. THE FOOD OF THE OYSTER.

OBSERVATIONS AT SAINT JEROME’S CREEK.—The following extracts, taken mainly from
my report for 1880 to the Fish Commissioner of Maryland, will give some idea of the kinds of

organisms usually encountered on oyster banks and beds. These observations were made at

730 NATURAL HISTORY OF AQUATIC ANIMALS.

Saint Jerome’s Creek, a few miles north of the mouth of the Potomac, during the months of July,
August, September, and October: ‘

“The food of this mollusk, as is well known, consists entirely of microscopic beings and
fragments of organic matter, which are carried by currents from the palps and gills, which have
been already described, to the large mouth of the animal at the hinge end of the shell. The inside
of the gullet and stomach, like some other parts of the body, are covered with cilia, so that food
once fairly in the mouth will be carried by their action down to the cavity of the stomach, where
it is carried into the folds and deep pouches in its walls, and even into the openings of the bile
ducts, to undergo digestion or solution, so as to be fitted in its. passage through the intestine to
be taken into the circulation, and finally disposed of in building up the structures of the body.

“Along with the food which is taken, a very large amount of indigestible dirt, or inorganic
matter, is carried in, which, in a great measure, fills up the intestine, together with the refuse or
waste from the body. This material, when examined, reveals the fact that the Oyster subsists
largely on diatoms, a low type of moving plants which swim about in the water, incased in minute
sandstone cases, or boxes, of the most delicate beauty of workmanship. These, when found in
the intestine, have usually had their living contents dissolved out by the action of the digestive
juices of the stomach. I have found in our own species of Oyster the shells of three different
genera of diatoms, viz: Campylodiscus, Coscinodiscus, and Navicula. The first is a singularly bent
form; the second is discoidal; and the last boat-shaped, and all are beautifully marked. Of
these three types, I saw a number of species, especially of the latter, but as I was not an authority
upon the systematic history of any of them I had to neglect the determination of the species. No
doubt many more forms are taken as food by the Oyster, since I saw other forms in which the
living matter inside the siliceous cases was brown, the same as in most of the preceding forms
which I have indicated. Some of these brown forms were so plentiful as to color a considerable
surface whereon they grew of the same tint as themselves.

‘“‘ Besides the diatoms and the spores of alge, the larve or young of many animals, such as
sponges, bryozoa, hydroids, worms, mollusks, are small enough to be taken in as aliment by
the Oyster, though their bodies in most cases being soft and without a skeleton, it is impossible
to find any traces, either in the stomach or intestine, of their remains, to indicate that they have
formed a part of the bill of fare of the animal. What, however, demonstrates that such small
larval organisms do help to feed the Oyster is the fact that at the heads of the small inlets o1
creeks along the Chesapeake, where the water is but little affected by the tides and is somewhat
brackish and inclined to be stagnant, there always appears to be a relatively greater development
of a somewhat characteristic surface or shallow water fauna of minute forms.

“In Saint Jerome’s Creek the microscopic fauna of its headwaters is entirely different from
that of the body of the creek; two minute forms inhabit in vast numbers the former, while I
sought in vain for them in the more open and changeable waters of the main body of the inlet,
which are brought into active movement twice a day by the action of the tides. One of these
forms, an infusorian,! one twenty-fifth of an inch in length, was found covering every available
surface of attachment, so that countless multitudes of the naked young would be swimming about
in the water previous to building the curious spiral tubes which they inhabit—admirably fitted in
this state as food for the Oyster. Besides the type referred to, there were a number of other
infusorians, which in their so-called swarming stages of development would become available
as Oyster food. Of such a pes I noticed four different itigiai 4 either belonging or very nearly §

‘On the occurrence of Freia producta, Wright, i in the LOhcen bake Bay.—Am. Naturalist, , 1880, pp. 810, 811.

LOCATION OF OYSTER BEDS. 731

related to the genus Cothurnia; all of the forms built tubes for themselves. I also noticed several
forms of bell animalcules, the swarmers of which would become available as food for the Oysters
lying in the vicinity.

“The diatoms did not seem to me to be more abundant in the headwaters than in the open creek.
There was one moss animal of remarkable character, which I found in the headwaters only. This
creature was very abundant, and no doubt its embryos, like those of the infusoria referred to, were
available as food. ;

“Of free-swimming infusorians, I noticed a number of genera; one especially attracted my
attention from its snake-like appearance and singularly rapid contortions; it had a tuft of vibrating
hairs or cilia at the head end in close relation with the mouth. Another more abundant type was
the curious genus Huplotes, with a thick shell inclosing the soft protoplasm of the body; the latter
was of an oval form, flat beneath and rounded on the back, so that the resemblance when the
large foot-like cilia were in motion, carrying the animal about, was strikingly like a very minute
tortoise, the resemblance being heightened when the animal was viewed from the side.

*Rod-like alg of minute size, the larve of crustacea, especially the vast numbers of extremely
small larval Copepoda, must enter as a perceptible factor into the food supply of the Oyster.

‘« There is no doubt but that the comparatively quiescent condition of the headwaters of these
inlets and creeks, available as oyster-planting grounds, are more favorable to the propagation of
minute life than the open bay or creeks, where the temperature is lower and less constant. Prac-
tically, this is found to be true, for oystermen seem to be generally agreed that Oysters ‘fatten’
more rapidly, that is, feed more liberally in the headwaters—blind extremities of the creeks—than
elsewhere. This notion of the oystermen is in agreement with my own observations during the past
year. Oystermen also assert that Oysters ‘fatten’ more rapidly in shallow waters than in deep
ones, a point upon which I made but few observations; but such as I did make tended to confirm
such an epinion. In illustration I may contrast the condition of the Oysters in the pond leased by
the commission at Saint Jerome’s and those dredged off Point Lookout, in twenty or thirty feet of
water, on the 3d day of October, 1880. The Oysters in the pond, by the middle or end of September,
were in good condition as to flesh, and marketable, while those from deeper water off Point Lookout,
and but little later in the season, were still extremely poor, thin, and watery, and utterly unfit for
market. These differences in condition, it seems to me, are to be attributed in a great measure to
differences of temperature and the abundance of food, but mainly to the latter.”

These observations give us some hints regarding the advantages arising from the cultiva-
tion of Oysters in more or less stagnant water, in which, as in the French parks or claires, an
abundance of microscopic life would be generated in consequence of a nearly uniform temperature,
higher in the early autumn months at least than the waters of the open sea, where cold currents
also would tend to make it still less uniform and thus interfere with the generation of the minute
food of the Oyster. In other words, it would appear that the effect of the French method is to
furnish the best conditions for the rapid and constant propagation of an immense amount of
microscopic food well adapted to nourish the Oyster. That unlike Oysters exposed to a rapid flow
of water on a bottom barren of life they grow and quickly come into a salable condition.

SITUATIONS BEST ADAPTED FOR OYSTER CULTURE.—In this country narrow coves and
inlets with comparatively shallow water appear to furnish the best conditions for the nutrition
and growth of Oysters; and according to my own experience these are the places where we act-
ually find minute animal and vegetable life in the greatest abundance, and, as might have
been expected, the Oysters planted in such situations appear to be in good condition early in

the autumn, long before those which are found in deeper and more active water, where their

732 NATURAL HISTORY OF AQUATIC ANIMALS.

food has less chance to multiply. If the French mode applies successfully to an inferior species,
ours, which grows so much more rapidly, ought to derive a proportionally greater benefit from
being treated in the same manner. However, before we are ready to deal with the material
on which the Oyster feeds, we desire a more perfect acquaintance with the microscopic life
which grows upon oyster-beds and swims about in the adjacent waters. From the fact that
the lower forms of life in fresh water often appear in great abundance one year, while in the
next, from some unexplained cause, none of the same species will be found in the same situation,
we may conclude that similar seasonal variations occur in the phases of the microscopic life of
a given oyster-bed and its vicinity. |

INFLUENCES OF ENVIRONMENT.—Such yearly variations in the abundance of microscopic
life are probably the causes of the variable condition of the Oysters taken from the same beds”
during the same season of different years. Violent or sudden changes of temperature are prob-
ably often the cause of the destruction of a great amount of the minute life upon which the Oyster
feeds. Backward and stormy seasons doubtless also affect the abundance of the microscopic life
of the sea. All of these questions have, however, as yet been scarcely touched, and, judging from
the disposition of many of our students of zoology to be content merely with a description of new
species and the compilation of lists, instead of also entering into investigations of the life-histories,
the relative abundance of individuals, and the influence of surrounding conditions upon the
forms they study, it will take some time yet before we get the information so much desired.
When we arrive at this knowledge we will know why it is that Oysters taken from a certain bed
are in good condition for a season or two and then for one or more years are found to be watery and |
of poor quality, as well as why it is that the Oysters of certain beds, which for years have had a_
high reputation for their fine qualities, are suddenly found to be more or less green in the beard, |
as I have been informed is now the case with the Oysters of Lynn Haven Bay, Virginia. |

As to the influence of brackish water in improving the condition of Oysters, let me observe ;
here that those who hold to that opinion appear to forget to bear in mind that brackish-water beds |
are often in the case just described; that lying in shallow, relatively quiet water, an abundance
of food is generated which is rapidly consumed by the animals, quickly bringing the latter into
condition, the brackish state of the water getting the credit of the result.

“Tn a paper published in the report to the British Government on oyster-culture in Ireland,
in 1870, Prof. W. K. Sullivan, of Dublin, remarked that independently of the mechanical constitu-
tion of the shore and littoral sea-bottom, 7. e., deposition of sediment, the currents, the temperature,
etc., the nature of the soil produces a marked influence upon the food of the plants and sedentary
animals that inhabit the locality, as well as upon the association of species. Especially is it the
case with Oysters, that the soil exerts so much influence on the shape, size, color, brittleness of
shell, and flavor of the meat, that an experienced person can tell with great certainty where any
particular specimen was grown.' . . . Were we able to determine the specific qualities of
tne soil which produce those differences in the qualities of Oysters, it would be an important step
in their cultivation. Again, soils favorable for the reproduction of the Oyster are not always
equally favorable for their subsequent development; and, again, there are many places where |
Oysters thrive but where they cannot breed. This problem of the specific influence of the soil is,
however, a very difficult and complicated one. First, because it is almost impossible to separate
the specific action of the soil from that of the other causes enumerated ; and next, because, though
much has been written on the subject of Oysters, I do not know of any systematic series of experi-

1E. INGERSOLL: Report on Oyster Industry, Tenth Census.

PROTOZOANS OF SAINT JEROME'S CREEK. 733

ments carried out upon different soils, and for a sufficient length of time to enable accidental
causes to be eliminated, which could afford a clue to the determination of the relative importance
of the action of the several causes above enumerated at the different stages of development of the
Oyster. . . . I believe the character and abundance of Diatomacea and Rhizopoda, and other
microscopic animals, in Oyster-grounds, is of primary importance in connection with Oyster
cultivation. The green color of the Colchester and Marennes Oyster shows how much the quality
may be affected by such organisms. It is probable that the action or influence of the soil of Oyster-
grounds upon the Oyster, at the various stages of its growth, depends mainly upon the nature and
comparative abundance of the Diatomacea, Rhizopoda, Infusoria, and other microscopical organisms
which inhabit the ground. I have accordingly always noted whete the mud appeared to be rich in
Diatomacea, Foraminifera, and other microscopic organisms. A thorough a study of a few differently-
situated Oyster-grounds, exhibiting well-marked differences in the character of the Oyster from
this point of view, by a competent microscopist, acquainted with the classes of plants and animals
just mentioned, would be of great scientific interest and practical importance.”

PROTOZOANS OF SAINT JEROME’S CREEK.—The Protozoan fauna of Saint Jerome’s Creek
presents considerable variety; several species of test-building Cothurniw were noticed, one
Vaginicola, three species of Vorticella or bell-animalcules, free-swimming Puplotes, Nassula; of
the latter type an exceedingly elongate form was noticed, with a body almost as slender as a
thread-worm. Monads were noted sometimes in profusion, though some of these may have been
the spores of alge. Ameceboid forms were very few, and the only one which was frequently
noticed was a form so nearly like Actinophrys sol that I would pronounce it the same.

The Freia producta Wright was most common; this creature is related to the fresh-water
trumpet animalcules, and is one of the most beautiful Protozoans I have ever seen. I reproduce
here, with some changes, my description of the Chesapeake form from the ‘‘ American Naturalist”
for November, 1850:

“The tubes in which the animalcule resides are formed of a narrow transparent ribbon of
horny consistency, wound into a spiral and terminating in a trumpet:shaped extremity, from which
the odd peristome of the inhabitant protrudes. The basal or attached end is usually bent at an
angle to the tube and bears a striking resemblance to the foot end of a stocking resting upon the
sole. This portion is not composed, like the tube, of a spiral ribbon, but is simply a thin-walled
sac, from the open end of which the ribbon takes its rise, but it is composed of the same kind of
material. Many of the tubes show a trumpet-like rim projecting from the sides of the former, a
little above the middle, and of the same form as the terminal rim, showing that this, like the form
described by Mr. Wright from British waters, may stop building its tube for a time and then
recommence.

“The adult animal, tube and all, when fully extended, will measure one twenty-fifth of an
inch in length. It is of the same color as Stentor ceruleus, or bottle-green, but has the power of
elongating and twisting itself as greatly as S. reseli. The peristome is quite unlike that of Preia
ampulla and bears a strong likeness to the blades of a pair of obstetrical forceps. The blades are
deeply grooved, forming a deep ciliated demi-canal with parallel sides, and at the junction of their
bases lies the spacious, twisted, and spirally ciliated pharynx, which is bounded dorsally and
ventrally by the prominent folds which unite on either side with the long, curved lobes of the
peristome. There is a small basal disc as in Stentor, and the ectosarc is traversed as in that genus
by parallel granular bands, regarded as muscular fibers by some writers. The usual food-balls
and vacuoles are present, and I was enabled to define sharply the endosare from the ectosarc,

734 NATURAL HISTORY OF AQUATIC ANIMALS.

and clearly see the nucleus. The tube or ribbon-secreting organ described by Wright I was unable
to discover. :

“ When fully extended the basal portion of the animal becomes attenuated to a thin bluish
filament, which widens towards the peristome, where the body is over half as thick as the inside
diameter of the tube. When fully retracted and resting, the animal resembles in its oblong shape
a retracted and resting Stentor, and measures about = as long as when fully extended. The
ribbon which forms the tube makes from four to twenty-four turns in specimens of different ages.”

This organism I since find to be an inhabitant of the bay also, but is not so abundant as in
the creek. Small mica collectors fixed to floating corks in the hatching jars and aquaria used
during the past season were found to afford a nidus for Freia as well as Zodthamnium, the latter
multiplying at a most astonishing rate in a very few days. Under similar conditions, amoeba,
apparently A. proteus, multiplied at a suprising rate; this was the case, too, with a small brown
diatom which would coat in three or four days the sides of the glass vessels with a thin brownish
film composed of countless myriads of individuals of the one species. The temperature of the
bay-water used in the aquaria at this time would range from 76° F. to 89° F. The Vorticellide
also soon attach themselves, and next to the hypotrichous infusorians found in the locality are the
most important animalcular forms found in the Chesapeake. At the mouth of the Cherrystone
River I last year found Licnophora cohnii in great abundance ectoparasitic upon an unidentified
hydroid. The heliozoén, Actinophrys sol, is found in the bay and Saint Jerome’s Creek, and I think
it capable of swallowing dead or enfeebled Oyster eggs and embryos.

MUTUAL RELATIONS BETWEEN THE OYSTER AND ITS PREY.—MObius calls an Oyster-
bank a Biocenosis or interdependent community of life. The many species of animals found
on the banks and beds are no doubt more or less mutually dependent upon each other for
subsistence, but this is perhaps not any more true of Oyster-banks than it is of terrestrial
faune. There are no doubt vast numbers of floating embryos of Oysters eaten by other
animals growing on the beds which bring their food supply to themselves by means of
currents produced by ciliary motion. On the other hand, there are no doubt vast numbers of the
minute swimming embryos of these, drawn in and swallowed by the Oyster, which may, indeed,
for aught we know, in this way swallow many of its own young, for the current produced by the
Oyster by means of the cilia clothing its gills is by no means a feeble one, though it is exceeded
in power by the current flowing into and out of the siphons of Mya. In the latter I have frequently,
upon opening the animal, found several Copepoda plainly visible to the naked eye swimming
about in the water in the inferior mantle cavity, which had evidently been drawn in by the inward
current. It is plain in this case that very mild means may become effective as prehensile and
destructive agents, so as to bring remotely related types into intimate vital relations.

Though an animal may be apparently invulnerable on account of the effectiveness of its
covering, it cannot emancipate itself from the abiding struggl« it has to make to obtain food, no
matter how passively it may appear to conduct itself. The Oyster has such a character, yet it has
been apparent from what has been observed before, that it is entirely dependent for a vigorous
existence upon the favorableness of surrounding conditions. The beds and banks in a true sense
are interdependent communities, whose vigor may no doubt be impaired by the removal of a single
one of its members. Suppose we should take away the algw, diatoms, Oyster-crabs, vibriones,
bacteria, infusoria, in fact all the minute life; we should greatly impair if not destroy the vitality
of the beds. While it is true that many of even the smallest forms may destroy food which
should propertly be consumed by the Oyster, that were it not for the presence of these same small
forms some destructive element might attain such a development as to be more injurious still.

CAUSE OF THE GREEN COLOR OF THE OYSTER. 735

There is therefore no doubt but that a delicate balance of power is maintained by these rivals
which is best for the health of the community. The stability of permanent oyster-beds, it must
be remembered, furnishes the right conditions for the survival of many types. It is a place where
they find both a home and plenty of food. It is the very favorableness offered by these places
which tends to induce them to congregate and multiply, and it becomes a serious question whether
the artificial establishment of banks will not in time cause the proper types to congregate and
multiply so as to afford the needed food supply for the Oysters. That destructive members of the
community may also be attracted is admitted, but if the beds are established in shallow waters, as
I have previously suggested, the destruction of such unwelcome intruders may be very readily
effected. ‘ Drills” and boring-sponges are naturally to be thought of as types which should be
destroyed, while diatoms, infusoria, small polyps, bryozoa, minute alge, etc., are to be favored in
every way. Those forms again which the oyster-culturist knows are only there for the purpose
of getting a good living with little trouble to themselves ought to be destroyed.

Tt might be an advantage to introduce certain desirable forms onto a bank, which might be
supposed to be useful as afood supply. Infusoria and diatoms not previously existing might be
introduced in this way; this, I think, would be especially easy in the case of the former where
the type was one which is fixed during its adult life.

216. ON THE CAUSE OF THE GREEN COLOR OF THE OYSTER.

EXPERIMENTS AT WASHINGTON. AND PHILADELPHIA.—I have frequently read accounts of
Oysters which had become green-fleshed in certain localities, and it has also been asserted that
competent chemists had discovered poisonous green substances of metallic origin in such speci-
mens. Tests made at the Smithsonian Institution by Professor Endlich in 1879 failed to disclose
anything poisonous in some green Oysters which had excited the suspicion of the Board of Health
of the city of Washington. This investigator, it is desirable to state, resorted to every test known
to him in order to discover if anything poisonous was present, and failing to discover any harmful
substance concluded that the color must be due to some inert material. In order to see if the color
was due to the presence of some green compound of copper, Prof. H. C. Lewis, of the Academy of
Natural Sciences of Philadelphia, kindly made some delicate tests for me, using small dried frag-
ments of an Oyster very deeply tinged with green in various regions, especially in the liver, con-
nective tissue, and mantle. The fragments were burned in a bead of microcosmic salt and chloride
of sodium on a clean platinum wire in a gas flame; this test did not give the characteristic sky-
blue flame which should have been developed had there been the minutest trace of copper present.

It is therefore clear that the substance, whatever it may be, is not a corrosive metallic poison
derived from copper, which if present would almost undoubtedly be detected by a peculiar acrid
metallic taste, which would be experienced when one ate such Oysters. In making some practical
tests as to the relative qualities of such Oysters as compared with white-fleshed ones, oppor-
tunities for which were kindly furnished me by Mr. J. M. Carley, of Fulton Market, I failed to
detect the slightest difference of flavor. Such also is Professor Leidy’s verdict, who informs
me that he made a similar experiment, and a restaurateur, with whom I discussed the matter,
declared that he was in the habit of selecting them for his own eating, preferring their flavor to
that of the white Oysters.

VARIATIONS IN COLOR.—If it be objected that the green color indicates an unhealthful
condition of the animal, it may be stated that other color variations of the flesh have fallen

736 NATURAL HISTORY OF AQUATIC ANIMALS.

under my observation recently. What is now alluded to is the yellowish, verging toward
a reddish cast, which is sometimes noticed in the gills and mantle of both the American and
European species. This, in all probability, like the green color, is due to the reddish-brown
matter which is contained in much of the diatomaceous food of the animal.

Mr. J. M. Carley has also called my attention to these variations, and was inclined to attribute
them to the soil in the vicinity of the beds. But if the classical writers are to be trusted, to the
green, yellow, and white fleshed sorts we must add red, tawny, and black fleshed ones. Pliny
tells us of red Oysters found in Spain, of others of a tawny hue in Illyricum, and of black
ones at Circeii, the latter being, he says, black both in meat andshell. Horace and other writers
awarded these the palm of excellence.—(O’Shaughnessy.) However, the black appearance may
only have been due to an abundance of the natural purple pigment in the mantles of the animal,
which varies very much in different forms; some, judging from the dark purple color of the whole
inside of the shell, must have the whole of the mantle of the same tint. The amount of color in
the mantle, especially at its border, varies in local varieties of both the American and European
species, as may often be noticed.

Sometimes almost the whole of the outside surface of the mantle is charged with dark purple
pigment cells. That copper is not usually the cause of the green color of Oysters I also have the
additional testimony of Prof. W. K. Sullivan, of Dublin, who says:

“As the green color of the mantle of Oysters from certain localities just referred to is
commonly attributed to copper, and as such Oysters are consequently believed very generally to
be poisonous, and their value therefore greatly depreciated, [ made the most careful search for
traces of that metal in the muds which I had received from grounds known to produce green-
bearded Oysters. Oysters and other mollusea placed in solutions containing copper and other
metals absorb them and retain them in their tissues. I have had two or three opportunities of
examining Oysters which had assimilated copper, owing to mine-water containing it being allowed
to flow into estuaries at places close to oyster-beds. In cvery case the copper was found in the
body only of the Oyster, which it colored bluishg-reen, and not in the mantle or beard, which was
not green. In the green-bearded Oysters which I have had an opportunity of examining, the body
was not green, and no trace of copper could be detected in any part of the animal. The color,
too, was not the same as that of the true copper Oysters, but rather that which would result from
the deposition of chlorophyl or other similar chloroid vegetable body in the cells.”

The American consumer, however, need not be alarmed about the presence of copper im our
species, as there are no beds on our eastern coast into which the washings from mines ever flow,
as we have no workable deposits of copper near any of our beds, as in Cornwall, England. Besides,
Iam inclined to doubt the statement of Professor Sullivan that Oysters or other mollusks can
absorb copper salts until their tissues are “colored. bluish-green.” Every competent histologist
knows how very readily organisms are killed by the action of inorganic acids and salts, several of
which are constantly used by biologists in fixing histological characters. Liebig, in his “* Animal
Chemistry,” long ago pointed out that the oxides and metallic compounds of antimony, arsenic,
copper, and lead had a very remarkable affinity for protoplasm, producing its immediate death.
In consequence, he suggested a very high chemical equivalency for living matter. This has since
been confirmed by the studies of Loew and Pokorny, who found that silver nitrate would produce
a reaction with protoplasm if diluted to the extent of one part to a million of water.

PROBABLE CAUSE OF THE GREEN COLOR.—It is highly probable that the green color of the
Oyster is due to the absorption from its food of a harmless vegetable pigment. In this country
green-bearded Oysters occur at Lynn Haven Bay, Hongers and York ivers, Virginia, on the

t

OBSERVATIONS OF GAILLON AND JOHNSTON. Tone

coast of New Jersey, in New York Bay, and Long Island Sound. I have seen specimens from a
number of these localities, and also tasted them both raw and cooked without being able to detect
any disagreeable or apparently harmful flavor.

Diatoms and green alge occur in great abundance in the stomach of the Oyster, especially the
former. The intestine is sometimes packed with countless numbers of the empty frustules or tests
of diatoms, mixed with dark, muddy ooze or sediment and very fine particles of sand or quartz.
It has been objected that the green color could not be derived from diatoms, because these organ-
isms are, aS a rule, apparently brown rather than green. This objection I find to be based upon
a misapprehension of the structure of the Diatomacee, as may be gathered from the following
general statement taken from Sachs’ ‘Text Book of Botany,” one of the latest and highest
authorities. On page 222 he says: ‘The diatoms are the only alge except the Conjugate in which
the chlorophyl occurs in the form of disks and bands, but in some forms it is also found in grains,
and the green coloring matter is concealed, like the chlorophyl grains in Fucacew, by a buff-colored
substance, diatomine or phycoxanthine.” It appears, then, according to the foregoing quotation,
that it is not impossible for diatoms to be the cause of the green tint in Oysters, which, let me
remark, is very nearly that of some pale green forms of those organisms which I have observed in
water from oyster coves where I have conducted microscopic studies. Both green and brown
diatoms may frequently be found in the stomach, and in making examinations to discover them I
find it best to thrust the nozzle of a pipette directly into the stomach through the mouth and
esophagus. The pipette should have a compressible bulb, so as to enable one to draw up the
contents of the gastric cavity into the tube without injuring the animal or taking up any fragments
of it to vitiate the experiment.

OBSERVATIONS OF GAILLON AND JOHNSTON.—Speaking of the abundance of the Navicula
ostrearia of Kiitzing, M. Benjamin Gaillon, in 1820, said that they inhabit the water of the
tanks or “ parks” in which the Oysters are grown in such immense abundance, at certain seasons
of the year, that they can only be compared to the grains of dust which rise in clouds and
obscure the air in dusty weather. Dr. Johnston, speaking of the French Oysters, says that in
order to communicate to them a green color, which, as with us (in England), enhances their
value in the market and in the estimation of the epicure, they are placed for a time in tanks
or “parks,” formed in particular places near high-water mark, and into which the sea can be
admitted at pleasure by means of sluices; the water being kept shallow and left at rest is
favorable to the growth of the green Conferve and Ulve; and with these there are generated
at the same time innumerable crustaceous animalcules which serve the Oysters for food and
tincture their flesh with the desirable hue.

This last remark of Dr. Johnston’s at first struck me as improbable, but I have met with great
numbers of small crustaceans, Copepoda mainly, in the branchial cavity of the common Clam (Mya
arenaria). Certain peculiar species have also been described by Allman from the branchial
cavities of ascidians. More recently, while investigating the contents of the stomach of the
Oyster, by the method already described, I find that it also swallows crustaceans, which are digested
and absorbed as food. The tests of nauplii or very minute’ larval crustaceans with the contents
digested out were frequently met with. Doubtless many very small Copepoda are also swallowed
and digested, but these are not green. Besides the foregoing, [ sometimes met with the very young
Shells of larval gasteropods and lamellibranchs; indeed, it is not improbable that the adult Oyster
may consume its own larve. The remains of bryozoa were also observed, such as Pedicellina
americana. The test of a peculiar elongate rhizopod and the cephalula stage of several worms
were also noticed. Of the smaller organisms usually associated with more or less clearly marked

47 F

738 NATURAL HISTORY OF AQUATIC ANIMALS.

putrefactive changes, one which I find almost uniformly present is a filiform or thread-like organ-
ism allied to Spirillum. It, however, was always found in the stomach in great abundance, and
especially in the pyloric portion of the intestine in which the crystalline style is lodged. This
organism is probably harmless; a similar one is frequently found in both fresh and salt water,
and has at times been developed in prodigious numbers in the reservoirs from which the supplies
of water were drawn for a large city, without any evidence of its having produced a harmful
effect upon those who drank of the water.

Vibws oF Lerpy, PUYSEGUR, AND DECAISNE.— Professor Leidy, at a recent meeting of
the Academy of Natural Sciences of Philadelphia, stated it as his belief that Oysters feed at
times on the zoospores of certain alge, as those of Ulva latissima (sea cabbage), which he knew
from personal observation to be green, and which he thought might possibly be the cause of
the green coloration of the soft parts of the animal as sometimes observed in certain localities.
Very possibly this may be the case, but judging from what I have seen and heard from oyster-
men, as well as from what I have read in various publications relating to this matter, I am not
inclined to regard this as the only source of the unusual green tint of the flesh of the Oyster.
I hope to be able to show that it is probably of vegetable origin, and therefore quite harmless.
That it is not copper we may be equally certain, as Professor Lewis’ tests have shown, for
any such quantity of a copper salt as would produce the green gills, heart, and cysts in the
mantle, such as are often observed, would, without doubt, be as fatally poisonous to the Oyster
as to a human being. The source of the green has recently been investigated by two French
savants, MM. Puysegur and Decaisne, who found that when perfectly white-fleshed Oysters
were supplied with water containing an abundance of a green microscopic plant, the Navicula
ostrearia of Kiitzing, their flesh acquired a corresponding green tint. These investigators also
found that if the Oysters which they had caused to become imbued with this vegetable green
were placed in sea-water deprived of the microscopic vegetable food the characteristic color would
also disappear. Whether this will finally be found to be the explanation in all cases remains to
be seen, as some recent investigations appear to indicate that it is possible that a green coloration
of animal organisms may be due to one of three other causes besides the one described above as
the source of the green color of the Oyster.

GEDDES UPON CHLOROPHYL-CONTAINING ANIMALS.—Patrick Geddes, in a recent number
of “ Nature,” has pointed out that the “list of supposed chlorophyl-containing animals
breaks up into three categories: first, those which do not contain chlorophyl at all, but green
pigments of unknown function (Bonellia, Idotea, etc.); secondly, those vegetating by their own
intrinsic chlorophyl (Convoluta, Spongilla, Hydra); thirdly, those vegetating by proxy, if one may
so speak, rearing copious alge in their own tissues, and profiting in every way by the vital
activities of these.” This latter is one of the most interesting and important of modern biological
discoveries, that living animal bodies may actually afford a nidus for the propagation of green
microscopic plants and not be injured but rather be benefited thereby. The oxygen thrown
off by the parasitic vegetable organism appears to be absorbed by the tissues of the animal host,
while the carbonic-acid gas thrown off by the latter is absorbed by the vegetable parasite, thus
affording each other mutual help in the processes of nutrition and excretion. This singular
association and interdependence of the animal host and vegetable guest has received the some-
what cumbrous name of Symbiosis, which may be translated pretty nearly by the phrase “asso-
ciated existence.” This is not the place for the discussion of the purely scientifie aspect of this
question as already ably dealt with by Dr. Brandt, Patrick Geddes, Geza Entz, and others, and

THE GREEN MATTER IN ANIMALS. 739

we will therefore only notice their researches in so far as they appear to have a bearing upon
the origin of the green color of the Oyster.

ENT’ DISCOVERIES.—Entz has discovered that he could cause colorless infusoria to become
green by feeding with green palmellaceous cells, which, moreover, did not die after the death of
their hosts, but continued to live, growing and developing within the latter until their total evolu-
tion proved them to be forms of very simple microscopic green algw, such as Palmella, Gleocystis,
etc. My own observations on some green-colored infusorial animals have been of so interesting a
character that I will here describe what I observed in a green bell animaleule ( Vorticella chloro-
stigma). Upon investigating their structure, I found that next the cuticle or skin in the outer soft
layer of their bodies, known as the “ectosare,” at all stages there was a single stratum of green
corpuscles very evenly or uniformly imbedded. In another form (Stentor), as already noticed by
Stein, the same superficial layer of green corpuscles was observed, reminding one very forcibly of
the superficial layer of chlorophyl grains observed in the cells of some plants, as, for instance,
Anacharis. Now, it is well known that certain animalcules are at times quite colorless and at
others quite green; this appears to be the case with Ophrydium. In this last case I have a
suspicion that vegetable parasites may be the cause of the green variety, but as for the others,
Stentor and Vorticella, I am not so sure that their green forms are so caused. In them the
superficial positions of the green corpuscles and their behavior toward reagents lead me to
think that they must be regarded as integral parts of the creatures in which they are found.

NATURE OF THE GREEN MATTER IN ANIMALS.—A grass-green planarian worm (Convoluta
Schultzit), found at Roscoff by Mr. Geddes, was observed by him to evolve oxygen in large
amounts, like a plant, and “both chemical and histological observations showed the abundant
presence of starch in the green cells; and thus these planarians, and presumably, also, Hydra,
Spongilla, etc., were proved to be truly vegetating animals.” While some organisms, like the
foregoing, appear to have true chlorophyl grains imbedded superficially in their own substance,
others, like the radiolarians, some siphonophores, sea anemones, and jelly-fishes, harbor true
vegetable parasites, or, preferably, vegetable guests.

That the green observed in a number of animal organisms is of the nature of chlorophyl,
or leaf green, has been proved by Lankester by means of the spectroscope. A. W. Bennett, in
alluding to Lankester’s observations, says: “In all cases the chlorophylloid substance agrees in
having a strong absorption band in the red—a little to the right or left—and, except in Zdotea, in
being soluble in alcohol, and in having strong red fluorescence, and in finally losing its color when
dissolved.”

The vegetable organisms which have been found to inhabit the lower forms of life alluded to
in the foregoing paper have been regarded as belonging to two genera, which Dr. Brandt has
named Zodchlorella and Zoébxanthella, and which are probably in part synonymous with the genus
Philozoon, afterwards proposed by Mr. Geddes. The latter gentleman, however, claims to have
first demonstrated the truth of the view that the yellow cells of radiolarians and polyps are alge;
Secondly, the foundation of the hypothesis of the lichenoid nature of the alliance between alge
and animal into a theory of mutual dependence; and, thirdly, the transference of that view from
the region of probable speculation into that of experimental science.

Hitherto no one has apparently noticed the occurrence of green vegetable parasites in
divalve mollusks except Professor Leidy, who has very kindly permitted me to use the facts
observed by him relating to Anodon, one of our common fresh-water Mussels. In this animal he
some years ago observed what must be considered to be algous parasites. He found them in
great numbers infesting the tissues of the Mussel and of a larger size than the nuclei of the cells of
the host in which they were imbedded. They were also provided with a nucleus, and were, there-

740 NATURAL HISTORY OF AQUATIC ANIMALS.

fore, not a part of the animal but a distinct vegetable organism. These facts, observed a long
time since, render it very probable that Professor Leidy was one of the first to notice the intra-
cellular parasitism of a plant in an animal.

The green color of the Oyster, as far as my experience goes, is not intense, as in Inany green
animals, such as we observe in Stentor, Spongilla, Hydra, ete., but is a pale pea-green tint. This
has been found to be the color of affected natives as well as of foreign ones, the gills and mantle
being usually most distinetly tinged. Exceptionally the heart is affected, its color sometimes
being quite intense.

EXPERIMENTS UPON EUROPEAN OystERS.—In studying some Oysters which were obtained
from England through the kind offices of Messrs. Shaffer and Blackford, in response to a request
coming from Professor Baird, certain ones were found which were decidedly green. Of these the
French specimens of Ostrea edulis, and a very singular form, labeled ‘‘ Anglo-Portuguese,” had the
gills affected, and in some of the latter the liver, heart,and mantle were very deeply tinged in
certain parts, so much so that I decided to make as critical an examination as my resources could
command.

Spectroscopic investigations gave only negative results, as it was found impossible to discern
any positive evidence of chlorophyl from the spectrum of light passed through thin preparations
made from specimens of green-tinted Oyster, some of which, like those made from the heart, are
decidedly green to the naked eye. There was no absorption noticed at the red and blue ends of
the spectrum, such as is observed when the light which enters the slit of the spectroscope first
passes through an alcoholic solution of leaf green or chlorophyl; indeed, the spectrum did not
appear to be sensibly affected by the green substance which causes the coloration of the Oyster.
No attempt was made to test the matter with the use of alcoholic green solutions obtained from
affected Oysters, as the former are not easy to get with a sufficient depth of color, because of the
relatively small amount of coloring matter present in the animals. Unstained (fresh) preparations
were used in all of these experiments.

COLORS IN DIFFERENT PARTS.—I find the liver to be normally of a brownish-red color in
both the American and European Oyster, sometimes verging toward green. When the flesh or
gills of the animal is green, the liver almost invariably partakes of this color, but in an intensi-
fied degree. The green stain or tincture appears in some cases to have affected the internal ends
of the cells which line the follicles or ultimate saccules of the liver. This color is able to survive
prolonged immersion in chromic acid and alcohol, and does not allow carmine to replace it in
sections which have been stained with an ammoniacal solution of that color, the effect of which
is to produce a result similar to double staining in green and red. The singular green ele-
ments scattered through the connective tissue remain equally well defined, and do not take the
carmine dye. I at first believed these to be parasitic vegetable organisms, and I also sup-
posed I saw starch granules in them, which physical tests with an iodine solution failed to con-
firm. These large and small green granular bodies in the connective tissue, and those close to
the intestinal wall, as well as those in the heart I, find present in fewer numbers in white-fleshed
Oysters, but simply with this difference, that they are devoid of the green color. It is evident,
therefore, that they cannot be of the nature of parasites, though the color is limited to them,
only the surrounding tissue, except in the region of the heart, appearing of the normal tint.
This condition of the specimens observed by me does not, however, disprove the possibility of
the occurrence of vegetable parasites in the Oyster, where there is as much, or perhaps more
likelihood of their occurring than in some much more highly organized animals.

It is a fact, however, that the Oyster is singularly free from true parasites of all kinds; the

COLORS OF DIFFERENT PARTS OF THE OYSTER. 741

oyster-crab being perhaps the only creature which is ever frequently found within its valves,
and then only as a harmless messmate. More recently it has been my good fortune to be able to
study a second lot of European Oysters, in two varieties of which the green color was unusually
developed, especially in the heart. In a specimen of Falmouth Oyster I found a large eyst or
sac in the mantle near the edge filled with green cells, which, like those in the heart, when opened
readily separated from one another, being quite as independent of each other as the ordinary
discoidal corpuscles in the serum of red blood. The hearts of affected specimens were found to
have the wall of the ventricle abnormally thick, and covered inside with the readily detachable
green cells in a thick layer and measuring one three-thousandth of an inch in diameter. An appli-
cation of the test for starch with iodine gave a negative result. If iodine was first applied to
these cells in strong solution, and they were then treated with sulphuric acid, the characteristic
blue reaction was not developed, showing that there was no cellulose wall covering them, and
that they were most positively not parasitic, algous vegetable organisms. In potassic hydrate
solution they were completely dissolved, a further proof of the absence of cellulose.

Their dimensions, one three-thousandth of an inch, is the same as that of the blood-cell of the
Oyster. They are nucleated, with the nucleus in an eccentric position as in the blood-cell of the
animal. Their occurrence in the heart and gills so as to tinge those organs of their own color is
almost positive proof of their true origin and character. Furthermore, I find in sections that they
sometimes occlude the blood-channels. In the cysts in the mantle, as in the heart, they are free,
and in the normal untinged heart they are not abundant. All of the foregoing facts indicate that
these green bodies are in reality blood-cells which belong to the animal. How they become green
is not easy to determine. The fact remains that no evidence of the presence of green Micrococei
or Microbia, as independent existences, could be made out. The fact that I found instances in green
Oysters where an unusual greenish material was found in the follicles of the liver, the living cells
of which were also affected, would indicate that the color was probably absorbed from the food of
the animal, which, as we know, consists largely of living vegetable matter. It is not improbable
that the tinged nutritive juices transuded through the walls of the alimentary canal acquired the
color of the food which had been dissolved by the digestive juices.

How to account for the accumulation of the green cells in the heart and in cysts in the
mantle is not, however, an easy matter, unless one be permitted to suppose that the acquisition
of the green color by the blood-cells is in reality a more or less decidedly diseased condition, for
which we have no ground in fact, since the green Oysters are in apparently as good health as the
white ones. They were found ‘fat’ or ‘poor,’ just as it may have happened that their food was
abundant or the reverse. They are also found in all stages of the ‘greened’ condition. Sometimes
they have only a very faint tinge of the gills, or they may be so deeply tinged as to appear
unpalatable, with the heart of a deep green, or with green cysts developed in the mantle, or with
clouds of this color shading the latter organ in certain places. A vastly greater proportion of
green Oysters are eaten in this country, at all events, than is generally supposed, especially of
those just faintly tinged in the gills.

The most important glandular appendage of the alimentary tract of the Oyster is the liver.
Jt communicates by means of a number of wide ducts with a very irregularly formed cavity, which
We may designate as the stomach proper, in which the food of the animal comes into contact with
the digestive juices poured out by the ultimate follicles of the liver, to undergo solution preparatory
‘to its absorption during its passage through the singularly formed intestine.

If thin slices of the animal are examined under the microscope we find the walls of the
stomach continuous with the walls of the great ducts of the liver. These great ducts divide and

742 NATURAL HISTORY OF AQUATIC ANIMALS.

subdivide until they break up into a great number of blind ovoidal sacs, into which the biliary
secretion is poured from the cells of their walls. A thick stratum of these follicles surrounds the
stomach, except at its back or dorsal side. It is not correct to speak of the liver of the Oyster as
we speak of the liver of a higher animal. Its function in the Oyster is the same as that of three
different glands in us, viz, the gastric follicles, the pancreas, and the liver, to which we may add the
salivary, making a total of four in the higher animals which is represented by a single organ in
the Oyster. In fact, experiment has shown that the secretion of the liver of mollusks combines
characters of at least two, if not three, of the glandular appendages of the intestine of vertebrated
animals. There are absolutely no triturating organs in the Oyster for the comminution of its
food; it is simply macerated in the glandular secretion of the liver and swept along through the
intestine by the combined vibratory action of innumerable fine filaments with which the walls of
the stomach, hepatic ducts, and intestine are clothed.

In this way the nutritive matters of the food are acted upon in two ways: first, a peculiar
organic ferment derived from the liver reduces them to a condition in which they may be absorbed;
secondly, in order that the latter process may be favored it is propelled through an intestinal
canal which is peculiarly constructed so as to present as large an amount of absorbent surface as
possible. This is accomplished by a double induplication or fold which extends for the whole
length of the intestine, the cavity of which in consequence appears almost crescent-shaped when
cut straight across. On the concave side the intestinal wall is thrown into numerous very narrow
longitudinal folds, which further serve to increase the absorbing surface. Such minor folds are
also noticed in the stomach, and some of these may even have a special glandular function. There
are no muscular fibers in the wall of the intestine as in vertebrates, and the sole motive force
which propels the indigestible as well as digestible portions of the food through the alimentary
canal is exerted by the innumerable vibratory cilia with which its inner surface is clothed. The
intestinal wall is wholly made up of columnar cells which are in direct contact externally with
the connective tissue which is traversed by numerous large and small bloodvessels devoid of
specialized walls.

This apparatus is admirably suited to render the microscopic life found in the vicinity of the
animal available as a food supply. The vortices created. by the innumerable vibratory filaments
which cover the mantle, gills, and palps of the Oyster enables it to draw its food toward itself,
and at the same time the microscopic host is hurled into the capacious throat of the animal to
undergo conversion into its substance as described above. The mode in which the tissues may
become tinged by the consumption of green spores, diatoms, or desmids it is easy to infer from
the foregoing description of the digestive apparatus of the animal; and the colorless blood-cells,
moving in a thin, watery liquor sanguinis, would, judging from their ameebiform character, readily
absorb any tinge acquired by the latter from the intestinal juices.

217. LOCAL VARIATIONS IN THE FORM AND HABITS OF THE OYSTER.

Mr. Darwin (‘Variation of Animals and Plants,” vol. ii, 2d ed., p. 270) writes: “With
respect to the common Oyster, Mr. F. Buckland informs me that he ean generally distinguish the
shells from different districts; young Oysters brought from Wales and laid down in beds where
‘natives’ are indigenous, in the short space of two months begin to assume the ‘native’ character.
M. Costa’ has recorded a much more remarkable case of the same nature, namely, that young

;

' Bull. de la Soc. Imp. d’Acclimat., viii, p. 351.

EFFECT OF HEAT UPON OYSTERS. 743

shells taken from the shores of England and placed in the Mediterranean at once altered their
manner of growth and formed prominent diverging rays, like those on the shells of the proper
Mediterranean Oyster. The same individual shell, showing both forms of growth, was exhibited
before a society in Paris.”

VARIATIONS IN THE SHELL.—The statement by Mr. Buckland in regard to the local forms of
Ostrea edulis is undoubtedly true, as I know from personal observation of specimens obtained for
me from various parts of Europe through the efforts of Professor Baird. In some cases the local
differences between the shells from different places were so marked that had a person mixed certain
lots together indiscriminately without my knowledge I could afterwards certainly have sorted out
the more marked varieties. Local influences also very largely determine the ‘“‘ greening” of Oysters,
as I can assert from personal obseryation of both the American and European species. Practical
oystermen affirm that they can readily discriminate the local varieties of Oysters grown in various
noted localities along the eastern coast of the United States. From what I have seen it is very
probable that this may be the case, as one may often observe well-marked differences of form as
well as color.

Local adaptation undoubtedly takes place, for how else are we to account for the fact that
a change in the specific gravity of the water to which the adult has been accustomed will kill the
milt? This point has an important practical bearing in relation to the effect of heavy rains in
diluting the water when the animals are spawning. Might not a marked change in the specific
gravity of the water at the time of spawning kill all the spermatozoa which are set free, and thus
also prevent the impregnation of whatever mature ova were being thrown out at that time by
the adults?

INFLUENCE OF TEMPERATURE.—Certain it is that temperature has an influence upon the
time of spawning. A lot of Oysters marked “ Anglo-Portuguese,” which had been transplanted
from Portuguese to English waters, and which I received in the month of March and others
in January last, had the reproductive organs remarkably advanced in development as compared
with specimens of O. edulis from different parts of England, Wales, Scotland, Holland, and France.
So great was this difference that, although planted for some time in the colder waters of England,
the reproductive organs of the Portuguese form had not apparently had their disposition to
become functionally active at this early season influenced to any great extent. In fact, I obtained
living mature eggs and milt from a number of specimens of this variety, while I looked in vain
for ripe spawn in any of the others of the true O. edulis. This would indicate that the influence of
temperature, though not altogether hereditary in this case, was persistent, and had so impressed
itself that the reproductive organs of these Oysters, coming from a warmer latitude, had begun
to mature their sexual products even after transplanting into more northerly and colder waters
much sooner than the natives of those same latitudes.

Like this persistent influence of a climate to which certain forms of Oysters have been long
accustomed, the influence of the specific gravity of the water of a certain locality may also be
persistent. The Oysters of Saint Jerome’s Creek seem to be adapted to the specific gravity of
the water of the vicinity, so that if artificial sea-water is prepared, differing much in this regard
from the native water, we find that the spermatozoa are immediately killed if put into it. From
this it follows that if the specific gravity to which the adults become accustomed is normal to
their sexual products, may it not be well to look into the effect of such changes upon the health
of the adults ?

I have met with spawning Oysters in December, such at least in which the spawn was nearly
Mature, but this was an exceptional case. I find them in April and May in considerabie abun-

744 NATURAL HISTORY OF AQUATIC ANIMALS.

dance; the months of May, June, and July may, however, be regarded as their principal spawning
months. Ripe spawn may be sparingly obtained in the latter part of August, and even up to
the first of October, but the three months mentioned are the periods during which the experi-
mentalist ought to be in the field prepared for work in this, the latitude of Washington. What
amount of variation from this period may be made manifest as we go north or south along the
eastern coast of the United States I am unable to state; and what amount of local variation may
also be due to causes of a purely local character I am also unable to say, not having examined
the Oysters at a sufficient number of localities to make such facts as I may possess of any
value.

218. THE OYSTER-CRAB AS A MESSMATE AND PURVEYOR.

It is many years since Mr. Say named the little Oyster-erab Pinnotheres ostreum, and its habits
since that time seem to have excited but little interest. Professor Verrill, in his observations pub-
lished in the “Report of the United States Fish Commissioner for 187172,” records the fact that
it is the female which lives in the Oyster, and that the male, which is smaller and unlike the
female, especially in the form of the abdominal segments of the body, is rarely if ever seen to
occur as a messmate of the Oyster, but that he has seen it swimming at the surface of the water
in the middle of Vineyard Sound. He also says that they occur wherever Oysters are found.
This singular little crab has quite a number of allies which inhabit various living mollusks, holo-
thurians, ete., of which admirable accounts are given by Van Beneden in his work on “ Animal
Parasites and Messmates,” and also by Semper in his treatise entitled ‘‘ Animal Life.”

QUADRUPLE COMMENSALISM.—The Oyster-crab is a true messmate, and it is in the highest
degree probable that the presence of these animals in the mantle cavity of the Oyster is to be
regarded as advantageous rather than otherwise. The animal usually lives between the ventral
lobes of the mantle of its host, into which the four lobes of the gills and palps also depend,
and, as will be seen from the following observations, may be the means of indirectly supplying
its passive protector with a portion of food. During a trip down the Chesapeake in July, 1880,
while I was with the Fish Commission vessel, some Oysters were dredged up by the crew which
contained some Oyster-crabs. In the case I am about to describe the included crab was a female
with the curiously expanded, bowl-like abdomen folded forward under the thorax, partially
covering a huge mass of brownish eggs. Upon examining these eggs, what was my astonish-
ment to find that they afforded attachment to a great number of compound colonies of the
singular bell animaleule, Zodthamnium arbusculum. Upon further examination it was found that
the legs and back of the animal also afforded points of attachment for similar colonies, and
that here and there, where some of the individuals of a colony of Zodéthamnium had been sepa-
rated from their stalks, numerous rod-like vibriones had affixed themselves by one end. In this
way it happens that there is a quadruple commensalism established, since we have the vibriones
fixed and probably nourished from the stalks of the bell animalecule, while the latter is benefited
by the stream of water drawn in by the cilia of the Oyster, and the last feeds itself and its protegé,
the crab, from the same food-laden current. Possibly the crab inside the shell of its host catches
and swallows food which in its entire state could not be taken by the Oyster, but in any event
the small crumbs which would fall from the mouth and claws of the crab would be carried to
the mouth of the Oyster, so that nothing would be wasted.

We must consider the crab with its forest of bell animaleules in still another light. Sinee
the animateules ave well fed in their strange position, it is but natural to suppose that they would

DEVELOPMENT OF THE OYSTER-CRAB. 745

propagate rapidly, and that the branches of the curious tree-like colonies would also inerease in
numbers. The individuals of the colonies multiply in about three ways: first, by branching ;
secondly, by splitting lengthwise; thirdly, certain much enlarged and overfed zodids divide cross-
wise. By the two last modes one-half of the product is often set free, the free animaleules
So originated being known as “swarmers.” These cast-off or free zodids which drop from the
colonies are no doubt carried along by the vortex created by the cilia of the gill and palps, and
hurled into the mouth and swallowed as part of the daily allowance of the food of the Oyster.
We mnay therefore regard Pinnotheres, in such instances, as a veritable nursery, upon the body and
legs of which animalcules are continually propagated and set free as part of the food supply of
the Oyster, acting as host to the crab. I do not suppose, however, that such a condition will
always be found to obtain, and it must also be remembered that myriads of Zodthamnium colonies
were dredged up attached to the fronds of the handsome Grinnelia, a red alga commonly found
in certain parts of Chesapeake Bay. Where this plant grows in abundance on the bottom I have
estimated that one might find upwards of a hundred animalcules attached to a square inch of
frond surface, which would indicate an animalcular population of upwards of four millions of
individuals to the square rod, a number as great as that of the human inhabitants of the city of
London.

DEVELOPMENT OF THE OYSTER-CRAB.—The Oyster-crab undergoes a development and
metamorphosis similar to that of our edible crab, Callinectes, but the body in the Zowa stage
is blotched with dark, branched pigment cells. The eyes also are vastly more developed than
in the adult, where they are partly suppressed from disuse. There is no dorsal spine, nor are
the antennary and rostral appendages so well developed as in the Zova of Callinectes. Arter the
young are hatched they probably leave the abdominal covering of the parent, swim out of the
Oyster for a season, and, if female, seek a permanent abode in some Vyster near by, behaving
somewhat like the species described by Semper as inhabiting the water-lungs of certain holothu-
rians. After undergoing further development, the young Pinnotheres reaches the megalops stage
of its development, when it is probable that the choice of its home takes place. After it has
entered the mantle cavity of its host as a diminutive larva, and has grown to be adult, when
it measures a half inch or more in diameter, it is probably ever after a prisoner within the
shell of its molluscan protector. It undergoes a retrogressive metamorphosis as it grows adult,
its eyes become relatively less conspicuous than in youth, and it never has a thick, hard shell
like its allies which live in the open water, but the external skeleton remains almost entirely soft
and chitinous, or in the state in which we commonly find the outer covering of an edible crab
which has just molted. This arises apparently from the conditions by which the animal is sur-
rounded; the protection afforded it by its host does away with the need of a thick, hard covering
such as we find inclosing the bodies of its free-swimming allies. Unlike the latter, too, the limbs
of the Oyster-crab are to some extent degenerate and weakened; its chele or claws are feeble,
and, when removed from its home, seems a very sluggish, helpless sort of creature, without a
particle of the pugnacity of its allies, and if placed on its back will sometimes remain in that
position helplessly beating the air with its weak limbs. This is a remarkable instance, which also
serves very admirably to illustrate the principle of degeneration in organic evolution, so ably
dealt with by Prof. E. Ray Lankester.

The Oyster itself is also an example of.the effect of disuse in producing retrograde develop-
ment, and even shows signs of gradual adaptation when removed from one locality to another.
Unlike most other bivalves, the Oyster has no soft muscular foot which it may protrude outward
from between the edges of its valves. No visible rudiment of such a prominence can be found

146 NATURAL HISTORY OF AQUATIC ANIMALS.

in the adult, though something of the sort, it is asserted by embryologists, appears to be devel-
oped in the larve. As the Oyster lost its power of locomotion from the non-development of
the foot, due doubtless to a gradually acquired sedentary habit which has become permanent.
the pedal structures have been almost entirely aborted, leaving nothing excepting the poorly
developed pedal muscles described by Dall. There is accordingly little or no evidence of the
existence of a pedal or foot ganglion in the Oyster, because there is no need for one, as in other
forms; it, too, has disappeared with the structure which required its presence.

Returning to the consideration of the Oyster-crab, it is well known that it is much relished
by many persons. The animal may be eaten alive, and has a peculiar, agreeable sweetish taste.

Recently an enterprising New York party has taken to canning them, the supplies for this purpose
being obtained from some of the large oyster-canning establishments. The economic value of the
animal as food, although not great, is sufficiently important to demand a passing notice.

219. PHYSICAL AND VITAL AGENCIES DESTRUCTIVE TO OYSTERS.

Most of the observations which follow were made at Saint Jerome’s Creek, Maryland, but
inasmuch as the physical and vital enemies of Oysters appear to be similar the world over, I have
no hesitation in reproducing what [ have previously published elsewhere. And of physically
injurious agents the black ooze or mud found in the vicinity or on the bottom of many of our
most valuable beds and planting grounds is probably the most to be dreaded if it accumulates
in too great quantity.

The origin of the black ooze at the bottom ean be traced directly to the sediment held in
suspension in the water which slowly ebbs and flows in and out of the inclosure, carrying with it
in its going and coming a great deal of light organic and inorganic débris, the former part of which
is mainly derived from the comminuted fragments of plants growing in the creek. This seemed to
be the true history indicated by what was noticed in studying the box-collector. The same opinion
is held as to the origin of this mud by both Coste and Fraiche in their works on oyster-culture.

There is probably no worse enemy of the oyster-culturist than this very mud or sediment.
It accumulates on the bottom of the oyster-grounds, where in course of time it may become deep
enough to cause serious trouble. Especially is this true of ponds from which the sea ebbs, and to
which it flows through a narrow channel. The falling leaves from neighboring trees in autumn
also contribute to this pollution, as well as heavy rains which wash deleterious materials into it.

Adult Oysters which are immersed in part in this mud struggle hard to shut it out from
their shells. If one will notice the inside of the shells of Oysters which have grown in a muddy
bottom, it will often be seen that there are blister-like cavities around the edges of the valves
filled with mud, or a black material of a similar character. There is not the slightest doubt
in my mind that in these cases the animal, in order to keep out the intruding mud, has had
recourse to the only available means at its command. A great many of the Oysters in the pond
are affected in this manner, but it is extremely uncommon to find shells of this kind in opening
Oysters coming from a hard bottom. It is easy to understand that such efforts at keeping out
the mud from the shell will not only waste the life forces of the animal, but also tend to greatly
interfere with its growth. The importance, therefore, of artificial preparation is apparent, where
it is desirable to establish ponds for the successful culture of this mollusk.

Only in one case have I observed that the mud tended to impair the flavor and color of
the Oyster. In this instance the animal was thoroughly saturated with the black ooze, the very
tissues seeming to be impregnated with the color, the stomach and intestine loaded to engorge-

ment with the mud, the animal manifesting every sign of being in a decidedly sickened condition.

EFFECT OF SEDIMENT UPON YOUNG OYSTERS. 747

The cause of this was probably that the shell with its tenant had sunken too deeply into the
mud when the ingestion of the black ooze commenced, giving rise to the remarkable changes
which I have recorded. No doubt had this condition of things persisted for long the animal
would have been smothered by the mud.

MUD AND THE YOUNG FRY.—The accumulation of the slightest quantity of sediment around
a young Oyster would tend to impede its respiration, and in that way destroy it, yet in the natural
beds there are so few naturally clean places which remain so that it is really surprising that so
many young Oysters pass safely through the critical periods of their lives without suceumbing to
the smothering effects of mud and sediment. When it is borne in mind that at the time the infant
Oyster settles down and fixes itself once and for all time to one place, from which it has no power
to move itself, it measures at the utmost one-eightieth of an inch, it will not be hard to under-
stand how easily the little creature can be smothered even by a very small pinch of dirt. The
animal, small as it is, must already begin to breathe just in the same way as its parents did before
it. Like them its gills soon grow as little filaments covered with cilia, which cause a tiny current
of water to pass in and out of the shell. The reader’s imagination may be here allowed to esti-
mate the feeble strength of that little current, which is of such vital importance to the tiny Oyster,
and the ease with which it may be stopped by a very slight accumulation of dirt. Mdébius esti-

mates that each Oyster which is born has 77323555 Of a chance to survive and reach adult age. So
numerous and effective are the adverse conditions which surround the millions of eggs matured by
a single female that only the most trifling fraction ever develop, as illustrated by the above caleu-
lation. The egg of the Oyster, being exceedingly small and heavier than water, immediately falls
to the bottom on being set free by the parent. Shauld the bottom be oozy or composed of
sediment its chances of development are meager indeed. Irrecoverably buried, the eggs do not
in all probability have the chance to begin to develop at all. The chances of impregnation are
also reduced, because the male and female Oysters empty their generative products directly into
the surrounding water, whereby the likelihood of the eggs meeting with the male cells becomes
diminished. What with falling into the mud and what with a lessened chance of becoming
impregnated, it is not unlikely that Mébius’ estimate is very nearly correct; but the American
Oyster, whose yield of eggs is much greater, not only on account of its larger size, but also
because the eggs are smaller than those of the European, has probably still fewer chances of
survival. The vigorous growth of small organisms on surfaces fitted for the attachment of young
Oysters also tends to cause sediment to gather in such places in the interstices of the little
organic forest, where the eggs of the Oyster no doubt often become entombed or smothered by the
crowded growth surrounding them.

‘‘ In addition to the active, animate enemies of the Oyster, the beds suffer seriously, at certain
times, from the elements. . . . Great storms will sweep the Oysters all off the beds, bury
them under shifting sand or mud, or heap upon them the drifting wrack torn from the shores.
Beds which lie at the months of rivers are liable to be injured by floods also, which keep the
water wholly fresh, or bring down enormous quantities of silt and floating matter, which settles
on the beds and smothers the Oysters.

“A few years ago a large tract of peat was drained at Grangemouth, Scotland. The loose
mud and moss was carried down the drains upon an oyster-bed in the estuary; the consequence
was that the Oysters were covered over with mud and entirely destroyed. Nothing is so fatal to
Oysters as a mud storm, except it be a sand storm. The mud and the sand accumulate in the
Oyster’s delicate breathing organs and suffocate him.

“North of Long Island an enemy is found which does not exist in the milder south, in the

— tt ini

748 NATURAL HISTORY OF AQUATIC ANIMALS.

shape of ‘ground-ice’ or ‘anchor-frost.’ It is little understood, though often experienced, and I
was able to collect only vague data in regard to it. It appears that in hard winters the bottom of
the bays freezes solid in great patches, even at a depth of fifteen or twenty feet. The mud freezes
so hard that rakes cannot be pressed into it; and if a stronger implement, like a ship’s anchor, is
able to penetrate it. the crust comes up in great chunks. These frozen patches are sometimes
forty feet square and continue unthawed for long periods. When such ‘anchor-frost’ takes place
at an Oyster-bed, of course the mollusks are frozen solidly into the mass, and few of them ever
survive the treatment. To the Cape Cod planters this is a serious obstacle to success.”?!

INTERFERENCE OF OTHER ANIMAL LIFE.—We have called attention to the probable inter-
ference of small organic growths to the fixation of the young fry; in practice it is found that the
larger organic growths which establish themselves on the collectors also become injurious. The
two most conspicuous types are the sessile ascidians or tunicates and the barnacles. I have
frequently found fully one-half of the surface of a slate covered with a dense colony of ascidians;
in this condition a great percentage of available surface is lost which ought to serve for the
attachment of spat. The surfaces so occupied would also be comparatively clean were it not for
these organisms, which actually become a serious annoyance. They, like the Oyster, affix
themselves to the slates while still in the free-swimming larval stage, since the surfaces designed
for the Oyster are equally well adapted to them. The barnacles, which also affix themselves in
great numbers, become a nuisance for the same reason. The larval barnacle is an extremely
active little creature, and dashes about in the water with great rapidity. As soon as it has
completed this stage of its growth it betakes itself to some object, to the surface of which it
attaches itself by the head end, when a singular change takes place, at the end of which it is
found that it has begun the construction of the curious conical shell which it inhabits. They
grow very rapidly, so that in a couple of months the shell will already measure over half an inch
in diameter. In this way further inroads are made upon the room which should be taken up by
Oysters. ;

Of course the larger types are not alone in taking up space, since infusorians, bryozoans,
polyps, ete., are also culpable, as well as alge, such as diatoms and the higher forms. ‘The only
remedy for this accumulation of animal growths on the surfaces of the slates and other collecting
apparatus will be to have the frames which hold the slate in position so arranged that each tile,
shingle, or slate can be removed, in order that it may be readily overhauled and these organisms
removed from the surfaces which it is desired shall remain clean. This work would have to be
done at intervals of every two or three weeks, and should be conducted with great care, so as not
to remove the Oysters which have affixed themselves along with the other things which it is the
jntention to destroy. The removal of the smaller forms from the surfaces of the slate would be
more difficult, and attended with danger to the fry already attached. With this object in view,
I would suggest the use of wooden racks or frames lying horizontally, which would receive the
slates into deep notches made with a saw, so as to hold them vertically or edgewise, rendering
their removal, for the purposes of cleansing, and their replacement an easy matter. Other
devices would no doubt answer the same purpose and be more convenient even than the last.
If posts were securely fixed in the bottom eight or ten feet apart, so as to project a foot or so
above the water at the highest tide, a single board six inches wide, nailed against the tops of the
posts edgewise, and extending from one to the other, would provide a simple arrangement from
which to hang the slates singly by means of galvanized wire fastened or hooked to nails partly
driven into the board. By the help of this plan one man with a boat could overhaul many

1. INGERSOLL, Report on Oyster Industry, Tenth Census.

ENEMIES OF THE OYSTERS. 749

hundreds of slates in a single day, and effectually care for them for a whole season. This last
contrivance would not answer well perhaps where there was a swift current, but would be a most
admirable arrangement in still ponds or ‘claires.’. In such places the whole area might be
provided with posts grouped or placed in rows, so that when the attendant was at work he could
pass in order from one row to the other in a narrow boat, or two attendants in one boat could take
care of two rows, the ones on either hand, at the same time.

Star-fishes are notorious for the havoc they are capable of making among Oysters. They
have the power apparently of everting their saccular stomachs and extracting the soft parts of
their prey from the shell. Whole beds have been seriously injured by the inroads of these
creatures. They do not seem to be dreaded much in the Chesapeake Bay, however, and appear
to annoy the oyster-planters of New England most seriously.

“The oyster-catcher, and some other birds, steal not a few at low tide. Barnacles, annelids,
and masses of hydroid growth sometimes form about the shells and intercept the nutriment of the
poor mollusk, until he is nearly or quite starved; this is particularly true in Southern waters. At
Staten Island the planters are always apprehensive of trouble from the colonization of mussels on
their oyster-beds. The mussels, having established themselves, grow rapidly, knit the Oysters
together by their tough threads, making culling very difficult, and take much of the food which
otherwise would help fatten the more valuable shell-fish. In the Delaware Bay the spawn of
squids, in the shape of clusters of egg-cases, appropriately called ‘sea-grapes,’ often grows on the
Oysters so thickly, during the inaction of summer, that when the fall winds come, or the beds are
disturbed by a dredge, great quantities of Oysters rise to the surface, buoyed up by the light
parasitic ‘grapes,’ and are floated away. This is a very curious danger. Lastly, certain crabs
are to be feared—chiefly the Callinectes hastatus, our common ‘soft crab,’ and the Cancer irroratus.
Probably the latter is the more hurtful of the two. I have heard more complaint on this score at
the western end of the Great South Bay, Long Island, than anywhere else. Mr. Edward Udall
told me that the crab was the greatest of all enemies to Oysters on the Oak Island beds. They eat
the small Oysters up to the size of a quarter-dollar, chewing them all to bits. These are on the
the artificial beds, for they do not seem to trouble the natural growth. But tolled by broken
Oysters, when the planter is working, they come in crowds to that point. Mr. Udall stated that
once he put down five hundred bushels of seed brought from Brookhaven, and that it was utterly
destroyed by these crabs within a week and while he was still planting. He could see the crabs,
and they numbered one to every fifty Oysters. It is well known that in Europe the crabs are
very destructive to planted beds, and it is quite possible that many mysterious losses may be
charged to these rapacious and insidious robbers. By the way, Aldrevandus and other of the
naturalists of the Middle Ages entertained a singular notion relative to the crab and the Oyster.
They state that the crab, in order to obtain the animal of the Oyster, without danger to their
own claws, watch their opportunity when the shell is open to advance without noise and cast a
pebble between their shells, to prevent their closing, and then extract the animal in safety.
‘What craft!’ exclaims the credulous author, ‘in animals that are destitute of reason and
voice.’”!

In a specimen of the common Ostrea virginica, recently handed me for examination by my
friend, Mr. John Ford, the substance of the shell was thoroughly cavernated so as to render it
extremely brittle and readily crushed; in fact, the inner table of the shell left standing showed a
great number of elevations within, which indicated points where the intruding parasite had been

kept out by the Oyster, which had deposited new layers of calcareous matter at these places so

1. INGERSOLL: Report on the Oyster Industry, Tenth Census.

750 NATURAL HISTORY JF AQUATIC ANIMALS.

as to give rise to the elevations spoken of. Besides this, the inner table had become so weakened
at the insertion of the adductor muscles that the animal in closing had torn a part of it loose,
which had been repaired by the deposition of a brown, horny substance. Evidence of the presence
of the boring sponge may very frequently be noticed in shells of Oysters brought to the markets,
though it often appears as if the parasite had left its work incomplete, being killed on its host.
I find that Schmidt has also noted this, and that the boring operations of the sponge usually seem
to stop in the case of living mollusks at the nacreous layer.

Upon examining some Scotch Oysters, obtained for me for study by Professor Baird,-I was
struck with the fact that every one was infested with this organism. The effect of the parasitism
was that all of the specimens had abnormally thick shells, due evidently to the effort made by
the Oyster to deposit more and more calcareous matter in order to exclude its persistent tormentor.
Internally the shell showed irregularities due to the intrusion of the sponge. Itis highly probable
that in this case the growth of the Oysters had been impeded by the parasite, in consequence of
the effort made by the animals to exclude their enemy by increasing the thickness of their shells.
This same tendency to increase the thickness of the valves I have noticed in specimens of our
native Oyster, the shells of which were infested with this parasite. It is very remarkable that the
Oyster should make an effort to exclude its enemy by such a means; and it is not less remarkable
to observe that the lime carbonate secreting function of the mantle is often stimulated to extra
exertion long before the parasite has actually intruded into the cavity of the shell.

Dr. Leidy gives a lucid account of the living sponge as found in Ostrea virginiana and Venus
mercenaria. He says: “This boring sponge forms an extensive system of galleries between the
outer and inner layers of the shells, protrudes through the perforations of the latter tubular
processes, from one to two lines long and one-half to three-fourths of a line wide. The tubes are
of two kinds, the most numerous being cylindrical and expanded at the orifice in a corolla form,
with their margin thin, translucent, entire, veined with more opaque lines, and with the throat
bristling with siliceous spicules. The second kind of tubes are comparatively few, about as one is
to thirty of the other, and are shorter, wider, not expanded at the orifice, and the throat unob-
structed with spicule. Some of the second variety of tubes are constituted of a confluent pair,
the throat of which bifurcates at bottom. Both kinds of the tubes are very slightly contractile,
and under irritation may gradually assume the appearance of superficial, wart-like eminences
within the perforations of the shell occupied by the sponge. Water obtains access to the interior
of the latter through the more numerous tubes, and is expelled in quite active currents from the
wider tubes.”

The boring process seems to be effected by the action of the living soft material of the sponge,
according to observations which have recently been made by a Russian naturalist, according to
whom it appears that the calcareous matter is dissolved away by the parasite. I am told by a
practical oysterman that a bed once planted with Oysters which are badly infested by the boring
sponge is apt to remain so for some time, and that the beds adjoining become infested, for the
reason that the embryo sponges, which are thrown off in large numbers from the infested “plants,”
swim about in the water, attach themselves to other Oysters, to begin their injurious growth and
excavations in sound shells.

220. NATURAL AND ARTIFICIAL OYSTER-BANKS.
CHARACTERISTICS OF NATURAL OYSTER-BANKS.—I have examined a number of oyster-
banks, which were readily accessible in shallow water, with gratifying results as to the habits
of the animal under virtually undisturbed conditions. These banks, like those formed by the

POSITIONS OF THE SPAT, 751

European Oyster, always appear to be much longer than wide, but many of them are almost
entirely exposed to the air during low tide, a rare occurrence, according to Mébius, with the
banks on the Schleswig-Holstein coast of the North Sea. I learned from the owners of
some of these banks that, although a considerable proportion of the Oysters on them were
at times frozen to death during the severe winters, the fecundity of those which remained was
such, combined with the naturally favorable conditions found on the banks for the growth
of old and young, as to restore the beds to their wonted productiveness in one or two seasons.
Whether this description of the fecundity of the beds found in shallow water is overdrawn
or not matters little, since there was the plainest evidence that we had here before our eyes
the best natural conditions for the propagation and feeding of the individuals. The beds are,
in a word, natural spat-collecting grounds; places where such conditions obtain as will allow a
large proportion of the swarming brood of the spawning season to affix itself securely and survive
in positions where an abundance of food may be got. The tide ebbing and flowing over the beds
not only carries with it in suspension the microscopic food best adapted for the nourishment of the
Oysters, but alse tends, owing to the peculiar arrangement of the shells on the banks, to keep the
surface of the latter clean, so as to be well adapted as favorable points of attachment for the young.
Tn all of the natural banks which I have had the pleasure of examining in the Chesapeake,
the individual Oysters assume an approximately vertical position.. The assumption of this position
seems perfectly natural; with the hinge end downwards and the free edges of the valves directed
upward the animals are in an excellent position to feed, while the outside vertical surfaces of the
valves are well adapted to afford places of attachment for the spat. The latter, however, appears
to attach itself in the greatest abundance to the old Oysters at the surface of the bank. The result
is that when one removes the Oysters from the bed they are found to adhere together in clusters,
generation after generation being piled one on top of the other in succession. As many as four
generations may be made out in most cases; the oldest being buried in the mud and sand below
and is often found to be smothered by those which have followed. Even below the last stratum
of living Oysters, if one keeps digging, it is discovered that the shells of numerous still more
remote ancestors of the living ones now occupying the bed are disposed vertically in the sand and
earth beneath. Attached to the upper edges of these dead shells follows, we will say, the first
living generation and so on to the fourth, composed mainly of young individuals or spat only a
few days or months old. Whether it is proper to regard the superimposed series of individuals as
generations may be questioned, but as no more expressive word occurs to me, I wish to be under-
stood as using it here with qualifications.
aq POSITIONS OF THE SPAT.—The spat does not fix itself in any constant position; the young
may have the hinge of the shell directed downward, upward, or to the right or left hand.
Singularly enough the shells do not grow in the directions which the free edges of the valves
are made to assume in the young. Should the young happen to be fixed hinge downward
the free edges of the valves grow in length directly upward; in case the hinge is directed
either to the right or to the left, the layers of calcic carbonate will be deposited in
such a way upon one side as to cause the free edges of. the valves to be eventually
directed upwards, causing the umbonal portion of the valves to describe an are of 909.
In case the hinge is at first directed upward, the layers of carbonate of lime will be deposited
_insuch a way by the mantle as to bring the mouth of the shell upward. The attempt to get
“into a vertical position will, however, not always be successful in cases like the last; the are of
“1800, which it is necessary for the animal to traverse from its starting point in order to build
its shell with the free edges opening upward, seem to be a feat a little too difficult of accom-
plishment, in spite of the wonderful persistence of effort manifested by the inhabitant.

752 NATURAL HISTORY OF AQUATIC ANIMALS.

The habit of growing in the erect position, where the banks are prolific and undisturbed.
causes the individuals to be very much crowded together, so that they do not have a chance to
expand and grow into their normal shape. From this cause. overcrowding, the shells of the
individual Oysters become very narrow and greatly elongated; the peculiar forms which result
are known to oystermen as “ Raccoon Oysters,” or ‘‘Cat’s-tongues,” the latter name being probably
derived from a suggestive resemblance to the tongue of a cat. Fossil Oysters appear to have had
the same habit. In some banks their crowded condition may be inferred from the fact that I
counted as many as forty Oysters in an area included by a quadrangle of wire including exactly
one square foot; thirty individuals to the square foot was a fair average on one bank
examined.

All of the observant writers upon the Oyster agree that it is essential that the bottom upon
which oyster-banks are to be permanent should not be liable to shift or be covered by mud or
sediment. The experience of the writer strongly enforces such a conclusion. The permanent
banks, owing to the great number of dead shells scattered through the bottom soil upon which
they have been established, acquire a peculiar solidity or fixedness which the currents of tide water
cannot sensibly affect. When these banks are once covered by the clusters of Oysters more or
less securely held together by the lower portions becoming imbedded in the soil below, and
mutually wedged and fitted together by the any msurfaces of contiguous clusters which have
become neatly adapted to each other by pressure, it is a very hard matter for the tides to smother
the bank unless sufficient soil in suspension is carried by the waters to completely cover the
animals.

ESTABLISHMENT OF ARTIFICIAL BEDS.—The inferences to be drawn from the foregoing
observations are very important. They naturally lead to the inquiry whether artificial Oyster-
beds cannot at least be established in shallow water, where the difficulties in altering the
character of the bottom so as to adapt it to the wants of the Oyster are not practically
insurmountable. I believe that the establishment of artificial beds, which would in time become
similar in every respect to. the natural ones, is possible in a moderately rapid tideway. The
localities, I apprehend, are abundant along the shores of the Chesapeake, and I certainly
know of few places where the existing natural conditions for such a project are any better
than those found in Saint Jerome’s Creek. The bottom would, of course, have to undergo such
preparation as would insure to it solidity, and it might be well to imitate the flat, ridge-like
character of the natural banks in constructing artificial ones. The long axis of the beds should
probably lie transversely to the direction in which the tide ebbs and flows in and out of the
creeks, aS appears to be the case with many banks examined. The next thing to do would be
to colonize these artificial banks with Oysters stuck thickly into the bottom, hinge downward,
imitating the position of the animals in the natural banks. The cost of such an experimental
bank would be comparatively insignificant.

Since the publication of the substance of the foregoing suggestion I have seen the idea
practically realized in the Cherrystone River, Virginia. A heap of Oyster-shells had been
scattered so as to form a low, solid elevation, which was submerged twice a day by the tide.
Upon tnis spat had caught and grown until the whole in two years was as completely and
solidly covered by living natural-growth Oysters as any good natural bank. The desirability
of using the poorly grown stock from natural and artificial banks as ‘seed” for planting
appears reasonable, and could no doubt be made profitable where banks of a sufficient extent
could be established, from which a supply of seed could be obtained.

SPAT-COLLECTORS. 753

I have been informed by an old oysterman that pine bushes stuck securely into the sea
bottom so as to be submerged in shallow areas have been found very effectual as collectors.
In fact, he told me that in one case which had fallen under his observation an oyster-planter
who followed this plan had the satisfaction of seeing his submerged bushes load with spat,
much of which afterwards grew to marketable size. Afterwards a productive ridge or bank
was the result where the brush palisade had originally acted as a collector. Thick palisades
of brush might be stuck into the bottom near permanent oyster-banks with good results.
Doubtless it would be possible to establish banks by this method if, in addition, oyster-shells
or stones were strewn on the bottom along either side of the brush palisade, in order to afford
a foundation for the fixation of the first generations of oysters.

SPAT-COLLECTORS.—Lieutenant Winslow, in 1879, used hurdles or nests of half-round tiles,
eight to sixteen in number; the results from one placed in the Big Annemessex were very flatter-
ing. After it had been immersed twenty-four days 1,506 Oysters had attached themselves. After
forty-five days had elapsed 1,334 still remained, and after ninety-three days were past the number
still adherent was 539. I have had no such success, but in other parts of the bay, as at Tangier
Sound for instance, spat falls in great abundance. I have seen the inner face of one valve of a dead
Oyster furnish attachment for over forty spat from one-eighth to three eighths of an inch in
diameter. Sponges, pieces of wreck, old shoes, pebbles, iron ore, leather, the external surface of
the shell of Modiolaria, branches of trees and logs which have fallen into the water act as collectors.
Oysters are sometimes found inside of bottles which have been thrown upon the bottom, the fry
having wandered through the neck and attached itself to the inner surface, growing to the size of
two inches in diameter and over. The spat is shaped much like the scallop or Pecten, a form which
it often retains until it measures more than two inches in diameter. The primary requisite in
collectors is that they shall present clean surfaces while the spawning season is in progress.
Small inequalities are probably an advantage, as the very youngest spat is often found in chinks
and angles on the shells of the adults. No other organisms should be allowed to grow and cover
up or smother the oyster spat. Barnacles, infusoria, moss animals, polyps, and many other
organisms are liable to accumulate on the surface of the collectors to the detriment of the young
Oysters which have established themselves. Many of these animals, polyps especially, eat the
young fry in the free-swimming stage, as shown by Dr. Horst.

The use of the methods employed abroad for collecting spat has not been tested in the United
States upon a scale large enough to enable us to arrive as yet at any very important conclusions.
Roofing slate coated with mortar promises good results; the valves of oyster shells strung upon
wire, pine cones, and brush have been used, but in unfavorable places, so as to vitiate to some
extent the results which were expected. <A coating of cement will not answer; it gets too hard,
sc that the spat when it is to be removed from the collectors cannot be loosened without injuring
its delicate, thin valves. The coating of lime and sand should be thick enough so as to make a
layer of at least an eighth of an inch over-the surface of the collector. It should also be allowed
to thoroughly “set,” as a stone mason would say, after it has been applied so as not to wash off
readily. A strong mortar should be mixed for the coating, composed of sharp sand and good
lime, in the proportions of about equal parts, and thin enough to dip the slates or tiles into the
mixture bodily. If the first coat is not found to be thick enough a second and third may be
applied. The tiles or slates after coating should be allowed to dry for two or three days so as to
allow the coating to “set” firmly.

48 F

754 NATURAL HISTORY OF AQUATIC ANIMALS.

Various ways of supporting the tiles and slates have been devised, cheap forms of which are
described in the treatises of Coste and Fraiche. The primary requisite in putting down collectors
is that they shall be so placed as not to be covered by mud, especially where the bottom is overlaid
with ooze. In such cases they must be supported so as to prevent their falling into the mud, the
effect of which would be to make them useless. In practice, I suspect, that it would be well to
look after the collectors occasionally and to brush off the mud, because in some places I have
noticed that thick deposits of sediment soon collect upon the upper surfaces. This accounts for
the fact that several observers have noticed that the spat is disposed to attach itself and survive
on the lower surface of the collectors.

T am informed by Mr. C. P. Hull that the practice of strewing oyster-shells as spat-collectors
on hard sea-bottom two or three fathoms deep is becoming quite common on the Connecticut
shores of Long Island Sound. Here, the practice is to scatter two hundred and fifty to three
hundred bushels of shells over an acre of bottom. The method there has also been so successful
and profitable as a means of increasing the area of the oyster fishery that the price of the dead
shells has increased and is likely to continue to do so, since the demand is greater than the supply.
Mr. Hull, himself a practical oyster-culturist, proposes to introduce this system into practice on
his projected plantations on the Chesapeake, where a beginning has already been made by this
method under the direction of Captain Hine, at Cherrystone, the supermtendent of the firm of
Maltby & Co., of Norfolk, now largely interested as planters in the Cherrystone River. This
method is the same as that extensively practiced in Europe.

How AN OYSTER TAKES ON FLESH.—Among oystermen the business of fattening or feeding
the Oyster is one of the most important, from the fact that upon the condition of the market.
able product largely depends its value. Fatness, so called, in the Oyster is a condition wholly
different in nature from the state known under that name in stall-fed domestic animals. The
turgidity of the reproductive organs is not usually indicative of fatness, as it appears some authors
have supposed, Mobius being the only one who has apprehended its true nature. The word “ fat,”
as applied to indicate the condition of the Oyster when in flesh, is a misnomer, since it is not fat
at all which is the immediate cause of the condition of plumpness which betokens a fitness for
market, but a very extensive deposit of protoplasmic matter which has been assimilated and laid
down mainly in the substance of the mantle. It is this relatively large amount of delicate, easily-
digested protoplasm, stored up in the palps and mantle, which renders the Oyster so wholesome
and nutritious.

The deposition of this protoplasmic material in the mantle, palps, and body stands in intimate
relation to the activity of the reproductive organs. During the spawning season Oysters are said
to be “ poor,” that is to say poor in condition, for at this time the mantle, especially where it lies
next the body on each side, is very thin and quite transparent; the radiating pallial muscles along
the border of the mantle, as well as its vessels and nerves, may now be readily studied under the
microscope, Owing to its transparency and the absence of opaque granular protoplasm. If we
examine the reproductive organs at this time, as a rule, we will find them greatly developed and
pouring out their products through two large ducts, the combined caliber of which is not far short
of that of the intestine. It will be evident to any thinking mind that if the major part of the food
inaterial elaborated by the digestive and nutritive systems goes to the ovaries or testes to be
transtormed into sex products, which are continually thrown off during the breeding season, little
of such material can be stored wp in the tissues of the body. We have described exactly what
happens. In the month of September, when the Oysters in this latitude are for the most part
done spawning, the drain of elaborated material having ceased to flow from the openings of the

FATTENING OF OYSTERS. Too

reproductive organs, it is diverted in another direction, but is retained in the system and has to be
deposited somewhere in the body. The most extensive deposits of this elaborated living matter
occur in the mantle, body, and palps, the color of which rapidly changes from the watery, trans
parent condition prevalent during the spawning season to a creamy white. The whole animal also
acquires a solidity which it did not possess before; it loses its watery, impoverished appearance,
together with its disposition to shrink to a fraction of its original bulk from an extensive loss of
fluids when opened. The mantle and palps become opaque and thicker than before, and their
substance is softer and more easily lacerated. The change here described undoubtedly affects the
connective tissue principally, as elsewhere stated. The material of the latter has the milky
appearance of the reproductive organ when mutilated, and may readily be mistaken for the latter
by the inexperienced. It appears that the generative and nutritive functions are opposed to each
other in the Oyster as in other animals; all of which indicates, too, the amount of energy which
must be expended during the breeding season in the production of germs. Whatever surplus
nutriment is stored up in the winter appears to be immediately devoted to the formation of germs
upon the arrival of the warm months, when food is also probably most plentiful and when the
external conditions are right for the development of the embryos. The effort which the Oyster
makes, at the expense of so much material, to reproduce its kind ought to be respected. In the
protection of the Oyster during the close season we are simply following the dictates of experience
and common sense.

The account which we have given above of the physiology and interdependence of the
fattening and reproductive processes of the Oyster, it seems to me, affords an opportunity to
point out how little philosophy there is in the doctrine that Oysters may be fattened by putting
them for a day or two in water less salt than that from which they were first taken, in order that
they may be water-swollen by the action of osmose, so as to give to them a plump appearance.
It is surprising how little dependence is to be placed upon the statements of oystermen and
fishermen in regard to the habits of the objects with which they are supposed to be most familiar.
And this statement, like many others of a similar kind, has no basis of fact and experimental
evidence to rest upon. I may sum up the utter absurdity of the widespread belief in the possi-
bility of fattening Oysters by removing them from salt to less salt water for a few days, by
saying that it amounts to the same thing as to assert that water is a fatty or oleaginous substance!

The results of my most recent investigations upon the minute anatomy of Ostrea virginica may
be fitly described in this place, since they have an important bearing upon the process of fattening.
The subject of this investigation was one of the most impoverished-looking Oysters which it has
ever been my fortune to find. It was collected on the 20th of July this present year (1882) and
placed in a chromic acid solution of one per cent. for forty-eight hours, when it was washed and
finally transferred to alcohol, to be cut into sections when convenient. This I have recently done.
When the specimen in question was fresh it was characterized by the almost perfect transpar-
eney of the mantle, and, as it afterwards turned out, the total atrophy of the generative organ.
Before the hardening process had been undergone, the mantle was greatly distended by watery
fluid, so much so that, after hardening, it had shrunken to about one-tenth of its bulk while in
the fresh and living state. The hardened specimen was cut into thin sections after imbedding in
paraffine, by means of a modification of the Taylor freezing microtome; the sections for thinness
left nothing to be desired, and revealed a condition of things different from any previously
observed by the writer in sections of either native or foreign Oysters. A careful microscopic
scrutiny showed that nowhere in the section was there a trace of even a rudiment of the genera-
tive network described as the atrophied condition in a previous portion of this paper. Not even

756 NATURAL HISTORY OF AQUATIC ANIMALS.

a trace of the connective tissue in which the rudiments of the latter are usually imbedded
remained, but the hepatic follicles or ultimate saccules of the liver were lying in immediate
contact with the mantle, with no tissue whatever intervening. I have hitherto found the liver
surrounded by a thick stratum of connective tissue in all of the specimens examined. The state-
ments in a previous portion of this essay in regard to the existence of vessels which traverse this
connective tissue mass will therefore have to be modified so far as to say that not only does the
connective tissue of the body mass completely disappear, but also the vessels themselves which
are excavated through its substance.

Turning now to the condition of the mantle, I find this in a no less remarkable state than the
parts already described. The ‘vesicular connective tissue cells,” as they have appeared to me
hitherto, have given place to an entirely different structure, apparently much less solid and
substantial. Instead of the clearly defined coarsely cellular structure usually noticed in sections
made from less impoverished individuals, the tissue has now become very coarsely areolar, all trace
of the peculiar nuclear bodies having vanished, together with the internal protoplasmic network
which they so clearly exhibit. The areole inclosed by the fibers of the connective tissue of the
mantle are very coarse and may measure as much as half a millimeter across in sections of the
hardened and shrunken specimen. When the mantie was gorged in life, with blood probably, some
idea of the coarseness of these meshes may be formed. The meshes may then have measured four
or five millimeters in diameter, the resulting cavernous state of this highly elastic tissue enabling
the mantle to become gorged or swollen by endosmosis to a remarkable degree, so much so as to
cause the animal to be apparently bulky, yet in reality distended with sanious fluids merely. The
question now arises, What has become of this connective tissue which has so completely disap-
peared? The only interpretation which I can offer is that the connective tissue substance has
been transformed into sexual products which have been poured out by way of the efferent sexual
ducts, and that our specimen represents the extreme of exhaustion consequent upon the completed
exercise of the reproductive function for the season. The animal, in other words, has now exhausted
its germ-producing resources, and must begin to feed and store up material for the next season’s ©
generative products. It therefore becomes highly prebable that the reproductive organs develop
anew each season. My reason for thinking so is, that in this specimen the atrophy or wasting
away of the reproductive organ has gone so far that no trace even of the efferent ducts of that body
remains. The specimen, taken as it was in July, also shows that the spawning season may be
completed before the end of summer.

The connective tissue of the Oyster is, therefore, in reality transformed into ova and sperma-
tozoa, depending simply upon the sex of the individual whether it shall be the former or the latter.
This also raises the question whether the same individual may not be of a different sex during
different seasons, since if appears that the whole reproductive organ disappears and develops anew
every year. This it is however to be noted is arguing from a very different basis from that of
some foreign writers who have been absurdly illogical enough to say that the Oyster was of a
different sex in different years, apparently forgetting that it would be impossible to open the same
individual twice in succession; since opening it kills the animal and puts the second examination
totally out of the question.

The function of the mesenchymal or connective tissue in the Oyster is, therefore, of the nature —
of a store of reserved material—protoplasm laid up for the purpose of conversion into germs as the |
reproductive organ develops anew. It is then in the highest degree improbable that it is of the —
nature ofan oily or fatty substance, out of which it would be impossible to form such highly vitalized |
bodies as the ova and spermatozoa of the Oyster. While it is true that we find the mesenchyme —

f

RESEARCH UPON THE FATTENING OF OYSTERS. T57

developed to the greatest extent during the winter when it may be said the Oyster is in the
best condition as regards flesh, it does not follow that this plumpness is due to fatty matters, but
rather to a larger amount of protoplasm filling up the mantle, palps, and body mass.

Our sections of the specimen described above show some other singular features which cannot
be passed over in silence. The principal of these is the presence of thick-walled vessels in the
ventral lobes of the mantle. In life we find branching vessels visible in the transparent mantle in
very impoverished specimens, such as the one under discussion. These vessels may be followed to
what are apparently their ultimate ramifications and seem to end abruptly. It is these vessels
which become obscured when the animal acquires flesh; they are, in fact, hidden in the thick
deposit of connective tissue laid down in the mantle. They are grayish or whitish in color as they
shimmer through the transparent external epithelial and connective tissue layers of the mantle
organ. They are also different in character from other vessels excavated in the connective tissue
of the mantle, and which disappear with the atrophy of the latter’s substance, just as we noticed
was the case with the vessels of the body mass. In a specimen as greatly impoverished as the one
under discussion, the thick-walled pallial vessels become very conspicuous in transverse sections.
They may not have the same function as the bloodvessels of the ordinary wall-less form found in
the connective tissue, from which type they may be at once distinguished by their thick, finely
cellular walls.

The almost total atrophy of the mesenchyme or mesoblast during the spawning season is a
very remarkable fact, no less so than its regeneration. It appears, however, as far as I have been
able to learn from transverse sections of very small spat, one-eighth to one-sixteenth of an inch
in diameter, that the absence of a well-developed connective tissue deposit also characterizes the
soft parts of the young animal. Indeed, the liver follicles here are relatively few in number,
whereas they are very numerous in the adult. The follicles in the young also lie in immediate
contact with the mantle, resembling in this respect the spawn-spent adults. This, for embryolo-
gical reasons, ought tobe so. We find, in fact, according to the unanimous testimony of observers,
that the mesoblast in the Oyster develops by the proliferation of cells from the outer and inner
layers into the segmentation or body cavity. Why, then, should it not be absorbed and regener-
ated in the same way in theadult? There seems to be no valid reason assignable why this should
not be so, if we look upon the mesenchyme with its vessels and areolar tissue and cavernous
spaces as having been primarily derived from the embryonic body cavity.

The arrangement of the intestine as shown in sections of spat as small as that described
above is essentially the same as in the adult. The second bend of the intestine crosses the
gullet in the same way, but the double lateral longitudinal fold or induplication is not so well

marked as in the intestine of the adult. The stomach is more nearly cylindrical and not so
irregular as in the adult. The contents of both the stomach and intestine show that diatoms
have formed a large proportion of the food of the young animal, in the sections of which, these
contents, in a number of my preparations, have been kept in situ.

The sections of the soft parts may be very readily double stained so as to bring out the
tissues of the reproductive organs very distinctly. To effect this, 1 throw the section into a
solution of methyl green for a few minutes, then into magenta, when it will be found that

_ the green will dye only the reproductive tissues, leaving the others scarcely tinged, while the red
"will stain the mantle, liver, and connective tissues, mapping out these parts so distinctly as to

“make a really useful as well as beautiful preparation.
a

Considerable care must be exercised in the preparation of the color solutions, so as not to
have them too intense. The sections should also be at once and quickly dehydrated or else the

758 NATURAL HISTORY OF AQUATIC ANIMALS.

alcohol will abstract the green and spoil in part the effect of the double stain. In making
sections, the best ones which I have ever made have been prepared from portions of whole
Oysters which had been imbedded in paraffine, the latter substance having in the molten state
interpenetrated all the cavities and spaces in the hardened specimen, which had been previously
dehydrated and saturated with oil of turpentine.

Note on the organ of Bojanus of the Oyster.—In the first part of this paper it is stated that the organ of Bojanus is
rudimentary or wanting in the Oyster. This statement must now be modified. Within the past year, M. Hoek, of
Leyden, has demonstrated the existence of the organ of Bojanus in Ostrea edulis, and the writer has shown it to be present
in the American species as a crescent-shaped glandular or canaliculated structure lying just below the adductor and close
against it, as a paired organ which also extends slightly into the substance of the mantle on either side. M. Hoek has —
shown that, as in other acephalous mollusks, this organ communicates with the pericardiac cavity and the genital
openings. Its function is excretory.

Valves of the heart.—A pair of very distinct valvular folds separates each of the auricles of the heart of the Oyster
frorn the ventricle, opening upward into the latter. They prevent the blood from regurgitating into the auricles, and
cause the blood-current to assume one constant direction, viz, from the auricles to the ventricles, and from the latter
through the anterior and posterior aortic vessels to the various parts of the body.

Fixation of the spat.—Recent studies have led me to the conclusion that the existence of a byssus in the fry of the
Oyster is very doubtful, and that fixation is accomplished at a very early stage, possibly twenty-four hours after the
embryos commence to swim, by the border of the mantle, as I have endeavored to show in my paper ‘‘On the Fixation of -
the Fry of the Oyster,’’ illustrated with figures, and recently prepared for the Bulletin of the United States Fish Com-_
mission, where I also show that the beaks of the larval valves are constantly directed one way, and that the hinge end
of the larval shell is inclined upward, the free margin of the left larval valve being brought into close contact with the ‘
surface to which attachment occurs through the instrumentality of the margin of the mantle. The attachment itself is a_
very firm one, and consists of the horny matrix of the calcareous material which serves as a cement to glue the free
margin of the lower valve of the fry and spat to the surface which has been chosen as a permanent abode.

q
}

SALTER TOS

PLATE 253.

THE COMMON SQUID.
Loligo Pealei (Le S.).

Drawing of female from Vineyard Sound, Massachusetts.

SSeS

THE GIANT SQUID.

Architeuthis princeps, Verrill.
Drawing by Prof. A. E. Verrill, from specimen obtained at Fortune Bay, Newfoundland, December, 1874.

THE SHORT-FINNED SQUID.

Ommastrephes illecebrosus (Le S.), Verrill.

Drawing of young male from Provincetown, Mass.

No. 1069

No. 1012.

Fic.
Fie. ¢
Fic.
Fig.
Fig. 5
Fig.

SEA SNAILS, PERIWINKLES,

. Lunatia heros, p. 700.

. Purpura lapillus, p. 698.

- Purpura lapillus, banded variety.
. Neverita duplicata, p. 700.

. Ilyanassa obsoleta, p. 696.

Tritia trivittata,

PLATE 254,

DRILLS, AND BORERS.

Fic. 7. The Whelk, Buccinumundatum, p. 699.
Fic. 8. The Periwinkle, ’ulgur carica, p. 694.
Kia. 9. Astyris zonalis.

Fic. 10. Astyris lunata.

Fic. 11. Rissoa aculeus.

Fig, 12, The Drill or Borer, Urosalpinw cinerea, p. 697.

Fia. 1.

Tia. 2.

Fig. 3.

Fig. 4.

TN) des

Fig. 5.

Fig. 8.

Angulus tener.

See Report U. S. Fish Commission. Part I, p. 677.
Animal reduced one-half.

The long clam, soft clam, or Nanninose, Mya
arenaria,

With animal in extension, reduced to one-half the nat-
ural size.

Tagelus gibbus.

See Report U.S. Fish Commission. Part I, p. 675, with
animal. The siphon not fully extended. One-half
natural size.

The Razor Clam, Ensatella americana, p. 707.
With animal extended. One-half natural size.

FG.

Fia.

FIG.

Fic.

Fia.

255.

5. The Razor Clam with some of the terminal
papille enlarged.
6. The Razor Clam, Lnsatella americana.
Shell natural size.
7. The Ship Worm, Teredo navalis.
Enlarged two diameters.
8. The Scallop, Pecten irradians, p. 709.
Natural size.
9. The Bloody Clam, Argina pexata.

Natural size.

PLATE 256.

, \ SZ Y \
ee ——> Fxoy \
Z
SVN SS by

SS = Sx
———— Z gy
a

Fig. 1. The Quahaug or Little-necked Clam, Venus mercenaria. V1G. 3. The Gaper Clam of the West Coast, Schizoth arus nut-

Natural size. talli (Conrad).

Fig. 2. The Quahaug of Puget Sound, Saridomus nuttalli. (1.) Specimen of ordinary size, reduced about one-fourth in length.

Natural size of lar; pecimen. Drawn by-J. H. Emerton phe eiplions ie somewhat contracted; the foot (I?) expands

(II.) Outline of the left valve of a larger specimen, reduced to the
same extent. Drawn from nature by R. I. C, Stearns.

PLATE 257.

=
=== SS
ee
SS =
aS ———
— SO, i = |
Sx SN
SN

————
SSS —_
aS =

ray rT Uy
i) Wee
Z

h
i ?
sare

TH

/ ,
Y Whi) i

i; - ° Mi
|
ey

4 i if Y
/ i. / (

/
ie i
1 Hy) :

LY;
Yy y de y ep

\ \ Ss = =
A / — —
1 C4 JIM TOY TAL
CTT TT
\ VY I 7 OY fit
\ ( al kth ‘)
h / | VA yi
AY AN MAN NY
\\ i Wye

HE PACIFIC.

ey;

vo =
an! _ ——

7 a Coy - vy - :
7 ‘ 7

<

i : - , —_ _— a -
» = aes 4 he Sap re ; Ee ye Ui Aan

5 or : > 7 _ -

PLATE 258.

Fig. 6.
MUSSELS AND SEA CLAMS.
Fic. 1. The Beach Clam or Hen Clam, Spisula soli- Fic. 3. The Mussel, Mylilus edulis, p. 709.
dissima, p. 708. Natural size. Vig. 4. The Black Horse Mussel, Modiola nigra.
1G. 5. The Rough Mussel, Vodiola plicatula, p. 709.

Fig. 2. The Sea Clam, Cyprina islandica. Natural

size. Fic. 6. The Horse Mussel, Modiola modiolus, p. 709.

%

a.

‘ear one
; Aad aft re ¢ Wik: ag Oa a> slbany’|
% »» ; ve e? “an

»y "a een f
? x .¢ ro 7 aay re n giilcisl een ; ; :
ine Wee ii mt i Tian roi maam Ahilias VU nian YH VARA ene ema ‘
; 7 ‘ 1a Mt a Meds) 3 ye t a ‘ =
one ‘ ' Ti. hat heay A yal as ap Tes § Bayi Gio. GAN: me

Lae airn
he eis Ko

Pea nen) 2 6.9).
EXPLANATION OF Fig. 1.

A. Hinge or anterior umbonal end of the left valve of an adult oyster, upon which the soft parts of the animal are represented as they lie
in situ, but with the greater part of the mantle of the right side removed.

au. The auricle of the right side of the heart contracted.

B. Posterior or ventral end of the left valve, which in lite is usually directed upward more or less, and during the act of feeding and respira-
tion is separated slightly from the margin of its fellow of the opposite side to admit the water needful for respiration, and which
also contains the animal's food in suspension.

Bm. Body-mass, traversed superficially by the generative ducts ge.

bj. The organ of Bojanus, or ‘renal’ organ, of the right side of the oyster. (The ducts which it sends into the mantle are not shown, nor
is its connection with the genito-urinary sinus s indicated.)

bp. The large branchial pores which open from the subdivided cavities of the pouch-like gills g into the cloaca el.

br. The anterior branchiocardiac ‘* vein,’ which conveys part of the blood from the gills to the auricle.

c. Right pericardiac membrane, which has been thrown back over M in order co expose the heart ve and au.

cel. Cloacal space, through which the water used in respiration passes out, and into which the excrement of the animal is discharged from the
veut ».

d. Nervous commissure of the right side, which connects the parieto-splanchnic with the supra-csophageal ganglion.

y. Gills, which extend as four flattened transversely subdivided sacs from the palps p to the pointy, at the edge of the mantle.

ge. Superficial network of the generative ducts as they appear when the oyster is spawning.

h. Groove in the hinge end of the lett valve, which receives the ridge developed in the corresponding situation on the right one.

j- Dark brown elastic body or ligament by which the valves are held together at the hinge.

M. Great adductor muscle, which is here viewed from the end, and which is attached to the inner faces of the valves over the dark purple
scars. Itopposesthe elastic ligament and closes the valves, and corresponds to the posterior adductor muscle of dimyary mollusks.

m. Mouth.

mt. Mantle of the left side fringed with two rows of tentacles.

ml’. Portion of the mantle of the right side.

n to z marks the extent to which the right and left leaves of the mantle are joined together; the hood thus formed above and at the sides ef
the palps is called the eueullus.

P. Palps exposed, a part of the cucullus on the right being eut away.

pd. Pedal muscle of right side, which is also inserted upon the shell of the same side,

pg. Parieto-splanchnie ganglion.

s. Genital opening of the right side.

sg. Supra-cesophageal ganglion.

». Vent or anus.

ve. Ventricle of the heart, which is dilated, or in the condition of diastole.

axe. Areas at the edge of the inner surface of the shell, where intruded mud has been inclosed by a thin lamina of shelly matter deposited
by the mantle. ’

y. Point at the posterior extremity of the gills, where the right and left leaves of the mantle are joined together by the membrane which
supports the gills,

EXPLANATION OF FIG. 2.

This figure was drawn from a dissection of a hardened specimen which had been removed from the shell, and is viewed from the left
side, the superficial tissues of the left half of the body-mass having been removed in order to display the surface of the ‘liver’ L, with its
large clusters of minute follicles, and part of the course of the intestine t. Atj the widened pyloric part of the intestine is shown, which
invloses the crystalline style. The ventricle ve and auricle are much contracted, and a spacious pericardiac space is shown on either sideof it.

ge. Stratum of reproductive follicles. The remaining letters of reference are the same as in Fig. 1.

EXPLANATION OF Fi4. 8.

This figure of the viscera of the oyster is also drawn in part from the hardened soft parts, but is viewed from theright side. The great,
ducts d of the ‘liver’ L are shown cut open longitudinally, and are represented as opening directly into the cavity of the stomach st, in front
of which the cesophagus oe is also shown running back from the mouth m. This figure shows almost the entire intestine, with its widened
anterior end j, and its course and curyature as here represented is what will be found constant, even when hundreds of specimens are
examined. Nearly all the substance of the body-mass has been carefully removed from the right half of the body; and where the edges of the
body have been cut through, the stratum of reproductive tissue ge is also shown. The corrugated outer surface of the inner or lower palp
at P. The remaining letters have the same significance as in the previous figures.

EXPLANATION OF FIG. 4.

This represents a section or slice cut from the soft parts of an oyster at the level of the dotted line o in Fig. 3, and viewed from its ante-
rior surface. The tissues and structures, which have been cut across in this section, are as follows:

a’. The dorsal or posterior branch of the great splanchnic artery.

a, The anterior or veutral branch of the splanchnic artery.

br. Branchial vessels.

c. The connective tissue which envelops the organs contained in the body-mass and forms the principal portion of the substance of the
animal in winter.

g. The gills cut across, showing their hollow interiors.

ge. Stratum of reproductive follicles, which immediately underlies the mantle layer mt. Intestinal canal cut through at two points, ii, pos-
teriorly and anteriorly, showing the manner in which the intestinal walls are folded inwards upon themselves.

LL. Right and left lobes of the liver, embedded in the connective tissue and most considerably developed at the sides and below the stomach.

sb. Suprabranchial space.

st. Stomach, showing its irregular form and connection by means of spacious ducts with the “liver.”

ve, Vena cava.

For explanation of figures see

opposite page,

PLATE 259.

LIBRARY OF CONGRESS

LN