BULLETIN

OF THK

MUSEUM OF COMPARATIVE ZOOLOGY

AT

HARVARD COLLEGE, IN CAMBRIDGE.

VOL. XIX.

CAMBRIDGE, MASS., U.S.A.

1890.

Reprinted with the permission of the original publisher

KRAUS REPRINT CORPORATION

New York

1967

Printed in U.S.A.

CONTENTS.

Page
No. 1.— Contributions from the Zoological Laboratory. XV. Studies on
Lepidosteus. By E. L. Mark. (9 Plates.) February, 1890 1

No. 2. — Contributions from the Zoological Laboratory. XVI. On the Egg
Membranes and Micropyle of some Osseous Fishes. By C. H. Eigenmann.
(3 Plates.) March, 1890 129

No. 3. — Report on the Results of Dredging by the United States Coast
Survey Steamer " Blake." XXXII. Report on the Nudibranchs. By R.
Bergh. (3 Plates.) March, 1890 155

No. 4. — A Third Supplement to the Fifth Volume of the Terrestrial Air-
Breathing Mollusks of the United States and adjacent Territories. By
W. G. Binney. (11 Plates.) May, 1890 183

No. 1. — Studies on Lepidosteus. Part I. By E. L. Mark.1

Contents.

I.

II.
III.

IV.

Introduction 1

Habits of the Young Fishes . 5
The Respiratory Function of
the Air-Bladder 13

Embryology ... ...

1. Egg Membranes ....

A. Observations ....

a. Zona Radiata and Vil-
lous Layer ....

6. Micropyle ....

c. Granulosa ....

d. Origin of the Zona Ra-

diata and the Villous
Layer

27
27
23

28
43
45

48

Summary 115

Postscript 119

Page

B. Historical and Critical Review of
the Literature on the Primary
Egg Membranes and the Mi-
cropyle in Fishes 54

a. Cyclostomata .... 54

b. Selachii 60

c. Ganoidei 63

d. Dipnoi 66

<?. Teleostei 67

1. Zona Radiata and Vil-

lous Layer .... 68

2. Capsular Membrane . 94

3. Micropyle and Plug . 102

4. Micropylar Cell . . . 110

Bibliography 120

Explanation of Figures 128

I. Introduction.

I became deeply interested in the embryology of Lepidosteus through
reading the paper on that subject published by Mr. Agassiz in 1878, and
determined to avail myself of the first opportunity of following up the
study. I desired particularly to pursue the development of the early
stages. A little later I was further incited to this by the brief account
of it which Balfour gave iu the second volume of his Comparative Em-
bryology (1881).

I had already formed plans for going to Black Lake, in the vicinity
of Ogdensburg, N. Y., in the spring of 1882, for the purpose of getting
material for the contemplated study, when I learned from Mr. Agassiz
that Balfour had in hand an extensive paper on the subject. Mr. Agas-
siz also informed me that he still had left a part of the material from
which Balfour had been supplied, and he kindly placed this at my

1 Contributions from the Zoological Laboratory of the Museum of Comparative
Zoology at Harvard College, No. XV.

VOL XIX. — NO. 1. 1

2 BULLETIN OF THE

disposal. I thought it would be desirable, nevertheless, to procure an
additional supply of eggs and embryos, and especially to endeavor to rear
the youug beyond the stages already in my possession.

On account of my duties in College it was impossible for me to leave
Cambridge until nearly the middle of June, — almost a month after the
usual time of spawning. Nevertheless, owing to the extreme backward-
ness of the season, I hoped that I might be able to procure some mate-
rial, and was confirmed in this by correspondence with Mr. J. H. Perry,
through whom I learned that up to a day or two before the time I had
fixed upon for setting out the gar- pike had not spawned.

I arrived at Black Lake on the evening of June 13th. The weather
had meantime grown warm, and the fish had already spawned, but I was
able to secure some eggs which were not very far advanced in develop-
ment. By a number of processes I killed and preserved at short inter-
vals sets of embryos which presumably belonged to the same lot of
spawn. The eggs which were collected from different localities were
kept in separate earthen-ware dishes and supplied with fresh water every
twelve hours. In this way the embryos were easily kept alive until they
hatched. Then they soon attached themselves by means of their pecu-
liar maxillary disks to the sides of the dishes, and near the surface of
the water, where they cluug with a tenacity truly surprising.

A number of eggs were preserved — principally by means of Kleinen-
berg's picro-sulphuric mixture — at intervals of a few hours, beginning
on the afternoon of June 14th and extending through several succeeding
days. This method was controlled at intervals by preservations made in
alcohol, in chromic acid, in osmic acid followed by potassic bichromate,
and in the last named reagent alone.

Besides the large number of embryos which were preserved at Black
Lake, I took away with me (June 20) many more — upwards of a hun-
dred— which had recently hatched. These living fishes were carried in
a narrow-necked tin pail, to the sides of which they adhered very firmly.

Instead of returning directly to Cambridge I took the gar-pike with
me to my summer residence on the south shore of Lake Erie, about
forty miles southwest of Buffalo, N. Y. Although this journey extended
over more than three hundred miles the fishes survived it well. The
greater part of it, however, was rendered comparatively easy, since it
was made by steamboat instead of railway. It is fortunate for such an
undertaking that these fishes have so large a yolk-sac, since it obviates
the necessity of procuring food for many days after hatching.

The question of being able to raise them beyond the stages already

MUSEUM OF COMPARATIVE ZOOLOGY. 3

secured by Mr. Agassiz so evidently depended on finding a suitable
food for them, that I spared no pains to accomplish this end. Many
kinds of meat and fish were minced and fed to them, but none of these
was acceptable. The minced liver, which Mr. Agassiz used with success
at first, was likewise refused. Fragments of meat were suspended in the
water by fine threads, but neither when moved about nor when left per-
fectly quiet did they seem to attract attention. Great numbers of water-
fleas (Cladocera) were put in the water with the young fishes, but the
latter made no attempts to catch them. It was not until after many
fruitless trials that organisms were found which were seized with such
eagerness, and so persistently, as to leave no doubt that they were the
natural food of the young gar-pike. These were the larvae of the common
mosquito. They constituted the exclusive diet of the young fishes until
the latter became large enough to catch and swailow minute " mud
minnows " (Fundulus), on which they subsequently fed as long as they
were kept alive.

When it was once ascertained that the young fishes would take mos-
quito larva?, there was no longer any serious question about the feasibil-
ity of rearing them, nor was it doubtful that these larvte formed their
natural food, for the shallow and quiet waters at the margins of Black
Lake and along the creeks which feed it abound in mosquitos. It
was by means of this diet that the fishes were kept in a thriving con-
dition during the stages immediately following the absorption of the
yolk.

From the 20th of June until the 1st of July specimens were, with a
few exceptions, killed every twenty- four hours; and from the 1st of July
until the beginning of August, usually at intervals of about forty-eight
hours.

By the 3d of August there remained besides those which had not
been preserved only about a dozen living fishes. On that date I started
for Newport, R. I., travelling by rail to New York. These remaining
fishes were carried by hand in a tin pail suspended by a spring ; but
owing to the difficulty of carrying in the pail a sufficient number of
mosquito larvse, and more particularly to the impossibility of properly
renewing the water, about half of them succumbed to the unfavorable
conditions of railway travel ,and were put into alcohol. One more died
on the way from New York to Newport ; but the remaining ones, hav-
ing been fed on larvae after my arrival at Newport, appeared to thrive.
At the end of a month they were taken to Cambridge, where they were
put into a large glass jar and supplied with running hydrant water.

4 BULLETIN OF THE

Here they were also kept on the diet of mosquito larvoe until from one
cause or another they had all died.

My failure to secure early stages of the eggs in the spring of 1882
made me desirous of repeating the attempt at a more seasonable time
the following year. With this object in view I left Cambridge for
Ogdensburg, May 18, 1883.

Judging from my previous experience that it would be difficult to
procure fertilized eggs in sufficient quantities without great labor, if they
were to be individually detached from the rocks, I procured several yards
of thin muslin of a color resembling the stones in the lake. I planned
sinking this and loading it with small stones in the water on some of
the "points" most frequented by the gar-pikes at spawning time. I
hoped in that way to secure a large number of eggs firmly attached to
the cloth, which I could then remove to a box suitably provided with
wire nettings to allow the necessary circulation of the water. Had it
proved successful, this device would have enabled me to have under
control the eggs thus acquired, and would have allowed me a degree of
certainty as to the age of the preserved material not otherwise easily
attainable.

Unfortunately for my plans, the weather proved to be in several ways
very unpropitious. A long period of cold and rain delayed the spawn-
ing to a time much later than common, and when at length, a few days
after the 1st of June, the weather and water became warm enough to
impel to the act of spawning, such high winds prevailed that it was
impossible to watch the movements of the fishes, and the most of them
had spawned before the water became quiet enough to allow one to dis-
cover their places of rendezvous. Some of the localities which they had
visited with the greatest constancy during the past years were appar-
ently deserted. Moreover, the cloths, which had of necessity been an-
chored near the shore, were either set free by the dashing of the waves,
or rolled into ropes which presented a comparatively small surface for
the reception of ova.

The limited time in the latter part of May left at my command, after
completing some work which I was compelled to take with me, was util-
ized in studying the ovarian ova of females captured before the spawn-
ing period arrived, and in some attempts at artificial fertilization. I
then succeeded in getting a fairly satisfactory knowledge of the interest-
ing structure of the e^ membranes and of the micropyle, but I did not
learn the peculiar relation of the latter to the granulosa until a few

.0

MUSEUM OF COMPARATIVE ZOOLOGY. 5

months later, when I had made microscopic sections of the whole ovarian
effff. including membrane and granulosa.

As the outcome of this journey I secured a number of series of eggs,
beginning with the early stages of segmentation, from which I prepared
at intervals and by various methods a considerable quantity of material.
I was also able to bring to Cambridge about two hundred young fishes
just hatched. Some of these were kept alive until September 2G, 1886,
— nearly three and a half years.

The fishes brought to Cambridge were put into running hydrant
water and fed on mosquito larvae for several weeks, — until about the
1st of August, — when they were large enough to swallow small " mud
minnows" of nearly their own size. These were gradually substituted
for the larvce, and those fishes which were large enough to avail them-
selves of this kind of diet grew much more rapidly than their mates.

I have also received some eggs from Mr. Perry since my last trip to
Black Lake, and although his attempts at fertilization did not prove t
be more successful than my own, I still hope to secure before long the
early stages which are needed to fill the gaps in my material.

II. Habits of the Young Fishes.

The habits of young gar-pike have already been quite fully described
by A. Agassiz ('78a) and Wilder ('76, '77), so that I shall not have
much to add to what has been previously published.

When first hatched the fish is so small in comparison with the size
of the yolk-sac that it swims only with the greatest difficulty, and its
movements are anything but graceful. It is so disinclined to swim, that,
were it left alone in water sufficiently pure to meet its requirements, I
have no doubt it would not move from the point of its first attachment
for many hours, or even days. When hatched in confinement the young
fishes always swim nearly up to the surface of the water and attach them-
selves to the sides of the dish. When there are a large number of them
they may attach themselves to floating objects. Frequently the super-
ficial film of the water — aided possibly by secretions from the oral disk
— serves to support an individual in the middle of the dish. Sometimes
half a dozen or more individuals form in a cluster, and appear to hang
suspended simply from the surface of the water. It is evident that they
are not merely floating in the vertical position, because in such cases
the surface of the water in their vicinity is always more or less depressed,
and upon the slightest touch the fishes begin at once to sink slowly ; if

6 BULLETIN OF THE

the water has not been too much disturbed, they make no motion while
sinking until they have nearly reached the bottom. Before they actu-
ally touch the bottom of the dish they appear to recognize their prox-
imity to it, and then begin to make vigorous efforts to swim up to the
surface again. This is apparently a very laborious undertaking, and, if
they fail to attach themselves at once, they again begin to sink slowly ;
they seldom attach themselves at the bottom, — especially if the water
has remained for some time unchanged, — but always as near the sur-
face of the water as possible. If there are too many to be accommodated
in a single row, those last to come crowd in between the tails of those
already attached, thus forming a second row ; but if there are still others,
they usually attach themselves to other fishes rather than take a lower
position on the sides of the dish. During the period of yolk absorption
they hang pendent and nearly motionless, except for the respiratory
movements ; those which hang from the surface of the water are verti-
cal, and any sudden motion in the water shows that their bodies are
quite limp. When the absorption of the yolk is well advanced, the
flexibility of the body is shown in a striking way by the snake-like
motions which the animal slowly executes while remaining attached.

The disinclination to swim lasts about as long as the yolk-sac per-
sists. With the gradual disappearance of the latter, the fishes show an
increasing tendency to swim about. When at length the sac is nearly
absorbed they rest in quite another way. They float near the surface,
taking a horizontal position, and remaining perfectly straight and mo-
tionless until disturbed ; whereupon, by vigorous strokes of the tail,
they swim away with remarkable celerity. In transferring the fishes
from one dish to another I was accustomed to use a small spoon, but
after the absorption of the yolk-sac I found it exceedingly difficult to
capture them in that way, so rapid were their movements: The stage
at which the fishes begin to swim and float is reached in eight or ten
days after hatching. Even at this early age locomotion is accomplished
by two distinct methods. The rapid motions are executed by vigorous
strokes of the whole caudal region. A slower, gliding motion is main-
tained by means of the very rapid vibrations of the extreme end of the
tail, which are so characteristic of the caudal filament at a later stage,
and by the still more rapid motions of the pectoral fins. Not only do
the pectorals vibrate when the tip of the tail is motionless, and vice versa,
but either of the pectorals may be in rapid motion while the other is at
rest. This second method of locomotion is apparently very serviceable
to the fish, in allowing it to approach its prey unobserved.

MUSEUM OF COMPARATIVE ZOOLOGY. 7

At a later stage of development, when the upper lobe of the tail is re-
duced to a caudal filament, this gliding motion is accomplished, princi-
pally at least, by the action of the pectorals. When the fish is advancing,
these fins are directed obliquely backward ; but when, as often happens,
the motion becomes retrogressive, they are directed more nearly at right
angles to the body. The motion of the fins is so rapid, that I have been
unable to determine by observation if, as is probable, the direction of
the stroke is reversed in the two cases. Not only the direction of the
long axis of the fin, but also the inclination of its transverse axis to the
horizon, is conspicuously changed at such times.

The vibrating movement of the caudal filament perhaps assists the
forward motion of the fish, but it cannot be considered essential to it,
since the filament often remains motionless while the animal is gliding
by means of the pectorals. The amplitude of the vibrations made by
the filament is not great in any case, — about 15°, — and the terminal
half alone is vibratory. When in motion the direction of its axis
is usually continuous with that of the spinal column, although it may
droop more or less while in motion, and is quite liable to do so when at
rest ; it then presents an even curvature, as seen from the side, and
often inclines a little either to the right or left.

When the fish is stemming a current, or, in swimming, is directing
the head downward, the caudal filament is kept in rapid vibration ; it
then takes a dorsal turn, and the curvature is rather abrupt at its base.
The whole curvature may amount to enough to make the extreme tip
of the filament perpendicular to the axis of the body, but usually it is
much less.

During the night of August 6-7, 1883, one of the individuals hatched
in June of that year escaped from the tank, and was found in the morn-
ing lying in only sufficient water to keep the body moist. Upon being
returned to the tank, though still able to swim, it showed evident signs
of weakness. The body was considerably arched, just as it has been fig-
ured for somewhat younger fishes by A. Agassiz ('7Sa, Tlate IV. Fig. 39,
and Plate V.). I think this case suggests an explanation of the peculiar
curved shape exhibited by the fishes reared by Mr. Agassiz. I had
already in the previous year imagined that the arched condition was not
common, for all my fishes were quite straight, at least so long as they were
well nourished. The curved condition of the escaped fish was apparently
due to muscular weakness ; the curvature was also accompanied by a
slight distortion from the sagittal plane. Inasmuch as it subsequently
regained its normal condition and became straight, I have no doubt that

8 BULLETIN OF THE

the curved condition is abnormal, and its appearance in the fishes raised
by Mr. Agassiz was probably owing to insufficient nutrition. The con-
trol of the pectorals in the case of this escaped fish was not lost, although
somewhat impaired. The fish was also able at once to execute vigorous
though ill-planned motions with the tail, and was therefore able to swim
rapidly, but in a reckless manner. The control of the caudal filament,
however, was entirely lost ; there was not the least trace of the rapid
vibratory movement, even when the pectorals were in active motion. By
the following day the use of the caudal filament had been partially re-
gained ; but its vibrations were rather feeble, and were resumed only
after long intervals of repose.

The temperature of the water greatty affects the power of locomotion,
and very cold water may even produce fatal results in a comparatively
short time. In the summer of 1882 I placed a dozen or more fishes in
the cold water of a spring ; within twelve hours half of them were dead.
The first signs of an abnormal condition are shown by uncorrelated
movements, reckless swimming, and the inability to keep the dorso-
ventral axis vertical. The appearance is as though the centre of gravity
were located above the centre of volume, and the fish gradually became
incapable of remaining in its normal position of unstable equilibrium. In
swimming the body rolls from side to side. After a time the fish sinks
to the bottom of the vessel, and can regain the surface only with consid-
erable exertion ; it cannot remain at the surface in a motionless condi-
tion. At length the body usually becomes curved sidewise. In this
condition the fish may remain for many hours, or even several days.
Restoration to fresh water of the ordinary temperature seems to have
only a temporary effect, or none. The only way to afford relief is to
place the fishes in direct sunlight until the water becomes warm, when,
if not already too much affected, they will gradually recover.

The movements of the eyes are principally in the horizontal plane.
When one eye is directed obliquely forward, the other looks obliquely
backward at about the same angle, so that the axes of the two eyes
are kept approximately parallel.

The manner in which young gar-pike capture and swallow their prey
is interesting, and serves to show why it is so difficult to get them to
feed on anything except living objects. When very young, as previously
stated, they will not feed on anything but mosquito larvse. The fish
always approaches the larva by a slow, even motion, resulting from the
vibration of the pectorals and the tip of the tail, until the prey is about
opposite the middle of the "bill"; then with a quick lateral motion of

MUSEUM OF COMPARATIVE ZOOLOGY. \)

the head the larva is snapped up. Occasionally it is bitten through,
and, whether struggling or not, is allowed to escape ; but the reason of
this I did not discover. Usually the larva is not snapped at until by
some slight movement it shows signs of being alive, and then only a
single snap is made. If unsuccessful, the fish remains quite motionless,
or glides slowly away by means of the same motion of the pectoral fins.
Fishes, especially when less than an inch in length and when well fed,
rarely make a lunge forward toward their prey when they snap at it ;
the motion is usually only a sudden sidewise bend in the neck region.
So cautious are the fishes not to snap at dead larvse, that, after they
have advanced so that the insect is opposite the middle of the bill, if it
does not move, they begin to swim obliquely forward, pushing the larva
before them without allowing it to glide backward along the bill. In
this way a larva may be pushed about several inches before it makes
the fatal movement which betrays its condition ; or it may, if it remain
entirely passive, escape altogether, since the fish, failing to discover evi-
dences of life, leaves it and glides off in search of other food.

The uumber of insects caught by a single gar-pike is undoubtedly
large. I was accustomed to feed the fishes twice a day. In July, 1883,
I had the curiosity to watch the largest of them, then a month old and
about 2\ inches (62 mm.) long, during its feeding. In the course of
ten minutes it caught twenty-one large mosquito larvse and made nine
ineffectual attempts at seizure. But the voracity of young fishes was
still more forcibly exhibited when, early in August, they were given
small minnows (Fundulus) for food ; for then they did not hesitate to
catch the minnows even when the latter were considerably larger than
themselves; but they succeeded in swallowing only those which were
of their own diameter or smaller. Since the minnows have much
thicker heads than the gar-pikes, the total weight of the former was
doubtless always somewhat less than that of the latter.

The minnows were caught in the same way as the mosquito larva;,
by a sudden sidewise motion of the head ; but being too large to be
swallowed at a single gulp, they were at first impaled on the sharp
teeth, and then by a series of deliberate movements put in a position
to be swallowed. Almost without exception, the minnows were swal-
lowed head first, irrespective of the region of the body first seized. If
caught near its tail, as usually happens, then the prey is moved be-
tween the jaws — to which it lies crosswise — by successive shiftings,
until it is held near the base of its head. A few movements usually
suffice to make it take a direction parallel to the jaws, and the head

10 BULLETIN OF THE

end of the prey is thus brought to lie in the gar-pike's throat, which is
often greatly distended by it. The movements by which the shifting of
the minnow is accomplished are rather complicated, and require a nice
correlation to be successful. During the process of transferring it cross-
wise between the jaws, the latter have to be opened quickly, and this
motion is instantly followed by a quick lateral motion of the whole head
in the proper direction. This lateral motion is accompanied by two
others • one a forward thrust of the whole body, and the other a de-
pression of the floor of the mouth. To accomplish the first movement
there is a preparatory curving of the post-anal portion of the body, the
sudden straightening of which at the instant the jaws are loosened gives
the necessary forward impetus, and helps to prevent the escape of the
prey ; this is further guarded against by the second motion, — the de-
pression of the floor of the mouth. The gill covers being in contact
with the sides of the body, this latter motion produces a tendency to a
vacuum in the mouth, which can be satisfied only by a sudden influx of
water between the jaws. The current thus produced of course has the
effect of carrying with it any movable object in the mouth or its imme-
diate vicinity, and of impeding the escape of the prey until the jaws are
again closed upon it. While the hold upon the prey is gradually shifted
from its tail region to its head region, the part of the jaws which holds
it is also not the same as at first. By the time the fish has been fully
shifted laterally, it will be very near the base of the jaws, for at each
loosening of the latter they have been thrust forward a little by the
motion of the whole body. But that is not all, for when the prey has
been shifted back to near the base of the jaws, — as one can see better
in the case of the larger gar-pikes, — each subsequent movement of the
latter causes the prey to take a slightly different direction, so that it is
finally swung around until it is parallel with the jaws instead of cross-
wise to them. I am not entirely certain how this is effected ; but it is
all accomplished when the fish is held in the jaws near their base. It
is possible that the teeth of one ramus of the jaw are not loosened quite
as promptly as those of the other, and that as a consequence they act
for an instant as a sort of pivot for the rotation of the prey. But that
both sides of the jaw. are ultimately set free at each motion is probable,
from the great liability of the prey to escape at this very critical step in
the process. Or it may be that the lower jaw is moved slightly toward
one side as the jaws are being opened, thus giving a swing to the prey
which changes its axis slightly before it is again caught by the closing
jaws. Whatever the means by which it is effected, it is certain that

MUSEUM OF COMPARATIVE ZOOLOGY. 11

this changing of the direction of the prey is all accomplished at the time
of the renewals of the grasp.

After the fish has been thus nearly oriented, its head end is introduced
into the throat by a single forward lunge on the part of the gar-pike.
These forward movements are continued for some time, the jaws being
slightly opened at each lunge. When the head is well introduced into
the gullet, the jaws are no longer suddenly opened and closed, but re-
main more or less gaping, while the prey slowly disappears, doubtless
being drawn on by peristaltic motions of the gullet. There are usually
slight motions of the jaws during this latter process, — a slow opening
and partial closing of them. The movement of the lower jaw is some-
what unsteady, almost tremulous, a peculiarity which is also seen, al-
though not so distinctly, at other times than when feeding.

The advantage of a great divaricability of the rami of the lower jaw
and of the fulness of the skin connecting them is at once apparent
when a comparatively large fish is half swTallowed, for then the thin
membranous floor of the mouth is greatly distended and the rami
pushed far apart. A side view of the head of the fish then resembles
somewhat the appearance of the throat of a feeding pelican.

Gar-pikes sometimes take food which they apparently discover to be
objectionable only after they have partially swallowed it. In such cases,
it is ejected from the throat with a sudden jet of water.

They do not hesitate to snap at each other when kept in confinement,
as I have many times observed, and as the mutilated condition of the
fins, and especially of the tail, makes very evident. I think it may be
inferred that they are not altogether free from danger from their own
kind when living in their natural baunts, for they always show a remark-
able sensitiveness to being touched in the region of the tail. The caudal
filament especially is so sensitive that the slightest touch from a foreign
body causes the fish to dart away with utmost speed, whereas one may
touch any other part of the body with comparatively little effect. The
young fishes become easily accustomed to the touch of the hands, and
may even be lifted altogether out of the water without offering any
resistance, provided it be done gently and without any quick motion.
But none of them ever become so tame as to allow the slightest contact
with the caudal filament without immediate efforts to escape. It is
almost invariably the tail end which is snapped at by their mates,
though I have a few times seen two individuals with interlocked jaws
carry on a short contest without fatal results to either. I have known
of only one case in which a gar-pike swallowed one of its mates. Near

12 BULLETIN OF THE

the end of July, 1883, I found an individual in the process of swallow-
ing a somewhat smaller mate. The bill of the victim and part of its
head were still protruding from the distended jaws of the captor ; so
that this individual was swallowed tail first, contrary to the more usual
method.

The movements of the gill covers vary in rapidity at different times,
but they are always executed with considerable promptness. Their
adduction is quickly followed by their abduction, but the interval that
follows before another adduction is usually rather prolonged ; it is the
more variable element. It may be so short as to make the abduction
and adduction separated by equal intervals, or it may be prolonged to
several seconds. These respiratory movements seldom exceed sixty per
minute, and may diminish during the torpor of winter to scarcely more
than one a minute.

The emission of bubbles of gas, which begins soon after the young
fishes detach themselves from their fixed supports, at first takes place
through the gills of one side. It is usually preceded by a forward
lurch of the body, accompanied by a slight rolling to one side and the
elevation of the gill covers. The bubble usually emerges before the fish
regains its normal position, and consequently comes through the gill
slits of the side which happens to be uppermost. Occasionally two
smaller bubbles escape from beneath the gill covei-s, one from each side.
When the fishes have become much older, the amount of gas is so great
that the bubbles often escape not only from beneath both gill covers,
but also through the mouth opening, and the rolling of the body does
not always accompany the escape of gas.

In the earlier stages of their growth the gar-pikes remain most of the
time very near the surface of the water in a horizontal position. In
such cases the only premonitory symptoms of the escape of gas are the
motions just described ; but as they grow older they gradually habituate
themselves to lying in deeper water, and then they almost invariably
ascend to the surface before emitting gas. The ascent is nearly always
accomplished by a slow forward and obliquely upward motion, the body
being at an ancfle of about 45° with the horizon. The motion is usuallv
deliberate, and at a uniform rate. After reaching the surface the body
is allowed to assume the horizontal position before any effort is made to
expel the gas. This motion of ascent is so characteristic, that after
studying their habits one may predict with tolerable certainty whether
a given fish is about to emit gas.

I believe the slight rolling of the body to one side is for the purpose

MUSEUM OF COMPARATIVE ZOOLOGY. 13

of bringing the slit in the roof of the throat, through which the gas
must be forced, into a position more favorable for its escape. If the
opening through which the gas is obliged to pass is directed downward,
its expulsion will require greater effort than if the opening is directed
sidewise. An advantage depending on the same physical properties of
the gas may perhaps also explain the universal habit of coming to the
surface of the water to disengage the bubble. At least, the pressure of
the water to be overcome in forcing out a bubble when the fish is at a
considerable depth must be greater than when it is near the surface.

The escape of gas, which may be several times repeated during the
process of swallowing a large fish, shows clearly enough that the bubbles
are not simply air taken in at the mouth to be immediately discharged
through the gill openings. The repeated emission of gas from the same
fish, without the possibility of any fresh air having been taken in through
the mouth, even led me to conjecture at one time that air was never
taken in through the mouth. At least, it was certain that the young
fishes often discharged gas without lifting any portion of the body out
of the water.

The rate at which gas escapes from the gill openings is extremely
variable, depending on the temperature of the water, the recency of
feeding, etc. Perhaps the following observations give a fair idea of
the rate during a warm summer day. In the course of ten minutes
(August 6) eight fishes together emitted forty bubbles, or an average of
one in two minutes for each fish. On August 17, a single fish, G2 mm.
long, came to the surface six times in ten minutes, and caused bubbles
to escape from the gills.

In the case of older fishes, snapping at the prey is frequently accom-
panied by an escape of gas, which is apparently involuntary, the sudden
motion of the head and the opening of the jaws being sufficient to cause
the escape of a few bubbles.

The nature of the gas will be considered in the following section.

III. The Respiratory Function of the Air-Bladder.

Lepidosteus, as well as some other fishes, has the habit of coming to
the surface of the water and emitting through the gill slits or the oral
opening bubbles of gas. This habit has attracted the attention of all
who have had the opportunity of examining the fish while living.

Poey ('55, p. 13G) observed that, when placed in a basin of water,
"every five or eight minutes he [Lepidosteus] would come to the sur-

14 BULLETIN OF THE

face to swallow a mouthful of air, returning downwards immediately.
One second after, half a dozen air-bubbles, some.quite large, escaped by
the opening of the branchiae The air," he adds, " remains in the blad-
der one second, sometimes one and a half, and this time is probably
sufficient for the absorption, digestion, and expulsion of the inspired air.
Besides, it is certain that, the animal not attempting to swim, the
bladder was not used in augmenting or diminishing the density of the
body, as most fish do, in order to ascend and descend in water." Poey
further strengthened his opinion that " some sort of pulmonary respira-
tion existed in the Lepidosteus " by dissections and injections of the
aorta, which showed the great vascularity of the bladder (pp. 134— 13G).

Louis Agassiz ('57), in exhibiting before the Boston Society of Natu-
ral History some young living gar-pikes, called attention to the fact that
this fish is " remarkable for the large quantity of air which escapes from
its mouth. The source of this Prof. Agassiz had not been able satis-
factorily to determine. At certain times it approaches the surface of
the water, and seems to take in air, but he could not think that so
large a quantity as is seen adhering in the form of bubbles to the sides
of the gills could have been swallowed, nor could he suppose that it
could be secreted from the gills themselves."

More recently Wilder ('70 and '77) also has studied the young of this
fish. He says ('76, pp. 151-153) : " Very often these young indi-
viduals of L. osseus, and more frequently the adults of the smaller
species (L. jrtcitystomus), would protrude the snouts from the water in
the respiratory act ; but the length of the jaws made it impossible to
determine whether this was intentional, and fur the purpose of inhaling
as well as of exhaling the air." He inclined to the opinion that air is
taken in as well as given out, because the fishes uniformly approached
the surface, whereas, if exhalation were alone sought, that " could be as
well accomplished at any depth." As the result of some experiments in
restraining the' motions of Amia, he says : " There seems no doubt that
with Amia there is a true inspiration as well as expiration of the air.
The same may be considered probable, though not yet proved, with
Lepidosteus"

So far as I know, these are the only published accounts of this pe-
culiar habit in the case of Lepidosteus. While Agassiz maintained a
conservative attitude regarding the question of the source and nature of
the bubbles, Poey and Wilder expressed the conviction that it was air
which had served the ordinary purposes of respiration, and both of
them supported their belief with arguments.

MUSEUM OF COMPARATIVE ZOOLOGY. 15

Close attention to the movements of young fishes kept in confine-
ment led me at first to doubt the accuracy of this conclusion. The
result claimed by Moreau ('63 and 'G3a, p. 820) — that, after the arti-
ficial removal of gas from the air-bladder of fishes generally, the gas
is regularly renewed, even when they are restrained from coming to the
surface — also served to confirm my doubts upon this point. Usually
it was only the tip of the bill which protruded from the water, and it
seemed incredible that such a movement could be sufficient for the
acquisition of even a limited volume of air. In addition, it has often
occurred that several times in succession a fish has been observed to
come near the surface and emit bubbles of gas without any portion of the
head region breaking the surface of the water.

This seemed conclusive upon at least one point: coming near the
surface could not be solely for the purpose of acquiring air. I have
given elsewhere (pp. 12, 13) what appeared to me to be the probable ex-
planation of the upward movement of the fish previous to emitting gas.

The possibility that fresh air was not always — perhaps not generally
— acquired, led me to reflect further about the possible functions of
the air-bladder. Starting with the assumption, that no organ arises
absolutely de novo, and that the air-bladder is the result of» a differen-
tiation in the alimentary tube, what, in a phylogenetic sense, was likely
to have been its first function 1 Did it arise as a hydrostatic apparatus
to be ultimately diverted to the service of respiration for the higher
vertebrates, or was the hydrostatic function already a superimposed
one'? Might it not be that the original function was purely one of
excretion ? Perhaps in so primitive a fish as Lepidosteus this original
function was still the dominant one.

These reflections led me to think it more than ever desirable to
subject the gas emitted by the gar-pike to chemical analysis, — really
the only method of arriving at definite and satisfactory conclusions.
I therefore determined to undertake an analysis as soon as the fishes
had attained a sufficient size to make the amount of gas given off in the
course of a few hours voluminous enough for easy experimentation.

Accordingly, in December, 1883, when the fishes I'emaining were six
or eight inches in length, some preliminary experiments were begun.
The analysis was attempted by using a bent tube of about 10 mm.
calibre, roughly graduated to 5 mm. ; but the result showed that satis-
factory conclusions were attainable only by employing more suitable
apparatus. Through the kindness of Professor Cooke the mercurial
bath and other apparatus for gas analysis at the Chemical Laboratory

16

BULLETIN OF THE

of Harvard College were placed at my disposal, and all the subsequent
work of analysis was carried on in that Laboratory. I am also indebted
to Professor Cooke for valuable suggestions during the progress of the
work. To Prof. A. V. E. Young, then a private student in the Chem-
ical Laboratory, I am under especial obligation, since he carried on the
manipulations and measurements of the gases. From his skill and
previous experience in gas analysis the results are entitled to more
consideration than if the measurements had been conducted by one
less familiar with such manipulations.

It was my aim in these experiments to ascertain, without sacrificing
the fishes, the composition of the gas in the air-bladder, or at least of
that which was emitted in the form of bubbles, presumably from the air-
bladder. No attempt was made to ascertain the results of branchial
respiration.

The collection of the gas, even from fishes 20 cm. long, is a tedious
process. An inverted glass funnel large enough to allow the fish to
swim freely inside, was first employed ; but the inclined sides of the
funnel not allowing the fish to assume a horizontal position except
when deep in the water, appeared to interfere with the emission of
the gas. After ascending to the apex of the funnel, the fish would
make violent efforts, apparently for the purpose of attaining the surface
of the water, but only occasionally would it emit gas under these cir-
cumstances, the emission usually
taking place only after it had be-
gun to descend. If freed from
the restraint of the funnel, the fish
invariably came at once to the
surface outside the funnel, and
emitted the customary bubbles.
Afterwards a nearly flat-bot-
tomed glass dish, only a trifle
smaller than the one containing
the fish, was inverted over the
latter (see Figure 1) ; but this
apparatus was only slightly more
successful than the one at first employed. The fishes came to the under
surface of the inverted vessel, and after long intervals some of them
emitted small portions of gas, but this was too small an amount to
be satisfactorily analyzed. Another method — the one finally employed,
although a tedious process — will be mentioned further on.

PlGUEE 1.

MUSEUM OF COMPAKATTVE ZOOLOGY. 17

In my preliminary analyses I had found that a very thin stratum of
air under the inverted vessel was sufficient to allow the ordinary emis-
sion of gas. The first experiment in which the gas was accurately
analyzed was therefore conducted upon fishes confined under the in-
verted dish, beneath which was a bubble of air of known volume,
which had been deprived of all its carbon dioxide. The details of the
experiment were as follows.

Experiment 1. — Dec. 13, 1883. At 11:45 a.m. six gar-pikes, varying
in length from 13 to 21 cm., were removed from running water ( + 12° C.)
to the experimental jar, containing recently distilled aerated water at
about the temperature of the room ( + 20° C), over which the glass
vessel, with a bubble of air (deprived of carbon dioxide) measuring
66.71 c.c.1 had been previously inverted. The experiment was con-
tinued until 3:15 p. m. (3| hours) without renewing the water. The
fishes were then taken out and the gas collected. In the final transfer
over the mercurial bath a portion of the gas was lost, so that its total
volume could not be ascertained.2 The portion remaining was collected
over mercury, and found to measure 19.27 c.c. (reduced). Treated with
potassic hydrate, the volume was diminished to 19.07 c.c. Absorbed,
.20 c.c. = 1.04% = carbon dioxide. This volume (19.07) transferred
to water and treated with pyrogallate of potash measured over water
16.27 c.c. Absorbed, 2.80 c.c. = 14.5% = oxygen.

Experiment 2. — Dec. 14, 12:30 p. M. Six gar-pikes (the same as in Ex-
periment 1) were removed from water ( + 11° C.) to the experimental jar
containing water at +21° C. The inverted vessel contained 65.20 c.c.
of air deprived of its carbon dioxide. The experiment was continued
until 4 p. M. (3^ hours). During the last hour all the fishes remained
at the top of the water, and became somewhat swollen in appearance.
One of the six did not recover from the effects of the abnormal
conditions. The gas, re-collected and measured, was found to have

1 The eudiometer employed was graduated to fifths of a cubic centimeter.
All the volumes given are the volumes reduced to 0° C. and 1 m. pressure.

2 In a preliminary experiment it was found that under nearly the same condi-
tions there had been a slight increase in volume. The conditions were as follows.
Dec. 3, 1883, 12:30 p. m. Four fishes (17-20 cm.) were transferred from cold water
into an experimental jar (Fig. 1, p. 16) containing water at +20° C. and a bubble
of ordinary air measuring 53 c.c. At 2:30 p. m. five other somewhat smaller fishes
were added. At 4:30 p. m. the experiment was discontinued, and it was found that
the bubble had increased to about 56.5 c.c, the increase being nearly 3.5 c.c.

vol. xix. — no. 1. 2

18 BULLETIN OF THE

diminished nearly 18.3% in volume ; it measured only 53.29 c.c. This
diminution, however, is evidently not to be accounted for as the result
of actual absorption by the fishes, but rather as the result of their over-
distention with gas swallowed, — probably in the vain endeavor to com-
pensate themselves for the altered condition of the atmosphere. The
recovered gas (53.29 c.c.) was divided into two portions (A, B), and
treated separately.

A = 43.20 c.c. (reduced) measured over water. This was treated
with potassic hydrate solution, but the volume remained unchanged.
Therefore carbon dioxide = zero. This volume (43.20 c.c.) was then
treated with pyrogallate, which reduced it to 38.88 c.c. The diminu-
tion, 4.32 cc, = 10% = oxygen.

B. The average of three readings made this volume = 10.07 c.c.
Treated with pyrogallate, it was reduced to 9.12 c.c, the reduction in
volume, 0.95 c.c, being equivalent to 9.4+ °j0 = oxygen.

Experiment 3. — The gas for this experiment was secured by collecting
the bubbles as they were given off by the fishes. A number of the gar-
pikes were placed in an uncovered experimental jar containing recently
distilled water at + 20° C. It was found that by using a small glass fun-
nel, — the one employed was about 65 mm. in diameter, — held near the
surface of the water, the fishes were not prevented from the ordinary
movements accompanying the emission of bubbles, as they were when
confined under a larger funnel. The funnel was held so that the tip of
the snout, but not the gill region, projected beyond its edge. The
otherwise veiy slow process of collection is somewhat hastened by em-
ploying a number of fishes in the same jar. As they rise one after
another, at comparatively short intervals, the collector, anticipating
their movements, holds the funnel in the proper position, and seldom
fails to secure the desired bubbles. But even in this manner the
amount to be collected in the course of a few hours is not large. In
this experiment the (reduced) volume of gas collected in about two
hours was 9.54 c.c. Treated with potassic hydrate, the volume was
reduced to 9.38 c.c. The difference = 0.16 c.c. = 1-7-% = carbon
dioxide. Treated with pyrogallate, the volume was further reduced to
8.20 c.c. The diminution, 1.18 c.c, = 12.4-% = oxygen.

For convenience of comparison the results of measurements may be
tabulated as follows : —

MUSEUM OF COMPARATIVE ZOOLOGY.

19

Volumes in c.c. reduced to 0° C. and
1 m. pressure.

Per cent Car-
bon Dioxide

Per cent

Original.

After Potas-
sio Hydrate.

After
Pyrogallate.

Oxygen.

I. Mixed air,
II. "

A,
B,
III. Respired air,

19 27
53.29
43.20

1007
9.54

19.07

43.20
9.38

16.27

38.88
9.12
8.20

1.04

0.
0.
1.7-

14.5+

10.
9.4
12.4-

In considering the significance of these results, it is to be kept in mind
that there are two principal problems involved. I have not attempted
to find out whether nitrogen is consumed or produced in this process ; but
simply to ascertain the changes effected in the atmosphere respired as
far as regards (1) the oxygen and (2) the carbon dioxide. The difficulty
in drawing at once a satisfactory conclusion from the analyses rests pri-
marily on the fact that the emitted gas could not be collected under
conditions which allowed it to be assumed that at the time of analysis
it was in the same condition which it presents in the air-bladder of the
fish. For previous to analysis the gas had bubbled through the water
in which the fishes were living, and had remained exposed to a limited
portion of its surface. The reduction of the proportion of oxygen con-
tained in the atmospheric air is so great, — between one third and
one half, — that the influence of the water upon the composition of the
emitted gas in this respect would certainly have been too insignificant
to modify essentially the result. With the carbon dioxide, however, the
case is different. The coefficient of absorption in water for the latter
is immensely greater than for oxygen, and the total amount of carbon
dioxide in comparison with the volume of the water to which it was
exposed is so small (never having exceeded 1.7% of the volume of gas
collected) as to make immediate deductions from the analyses of little
value.

In a series of very carefully conducted experiments upon the intestinal
respiration of Cobitis fossilis, Baumert ('53) arrived at the conclusion
that the gas from the intestine, in bubbling through the water and
during its subsequent exposure to that liquid, was not essentially altered
either by the water or the gases contained in it (p. 48). The condi-
tions under which his collections of gas were made l were so like

1 Baumert ('53, p. 39) employed five or six fishes (Cobitis fossilis) of medium size
which were kept in a vessel containing about twelve litres of water from the river
Oder. The gas was collected by means of a large inverted funnel terminating
in a small-necked receiver, and usually about two hours were required for its
accumulation. Three analyses, made at intervals of three days without any

20 BULLETIN OF THE

those which I employed, that it seems justifiable to make use of his
conclusions in the present case. The ingenious device employed by
Baumert ('53, p. 46), in verifying the accuracy of his previous results,
to suppress the branchial respiration, and thus secure the effects of
intestinal respiration alone, could not, from the nature of the difference
between the modes of respiration, be made available in the case of
Lepidosteus.

The means (viz. protracted boiling) which Baumert employed for
extracting the absorbed gases contained in the water of experimenta-
tion were as complete as the chemical methods at his time permitted.
Since then, however, Grehant ('69) has shown that simply boiling gas-
impregnated water, although sufficient to eliminate all the oxygen and
nitrogen, does not remove all the carbon dioxide, but that a combina-
tion of the mercurial pump with the method of boiling is capable of
accomplishing this result. By this process he has demonstrated that

renewal of the water, gave in 100 volumes of gas respectively 1.77, 0.47, and 0.13
volumes of carbon dioxide, and 10.46, 13.71, and 11.92 of oxygen. It will be seen,
therefore, that not only the conditions under which the collections were made have
been in both cases very similar, but also that the composition of the gas as deter-
mined by analysis was nearly the same in Lepidosteus that it was in Cobitis. Since
the ratio of the gases in the two cases was practically the same, there is no reason
to suppose that the water absorbed a greater proportion of gas in one instance than
in the other.

As regards the temperature of the water at which the experiments were made,
although not definitely stated by Baumert, it is safe to infer, from the temperature
at which his numerous experiments on branchial respiration were made, that it was
considerably lower than the temperature of the water in which the Lepidostei were
placed, so that the tendency to an absorption of carbon dioxide in the latter case
would certainly have been less than in Baumert's experiments.

One of the plans adopted by Baumert to test the influence of the water and its
contained gases upon the emitted gas — whether the latter were either deprived of
any of its oxygen or carbon dioxide, or received accessions while exposed to the
water — was (11 to prepare artijicial mixtures of atmospheric air and carbon diox-
ide in different proportions (4 : 1 and 6:1) and cause them to bubble through water
in which fishes were living, and after collection to allow these gases to remain
exposed to the water, as in the experiment with the natural gas ; (2) in a similar
way, to cause atmospheric air to pass through water in which the fishes had been
living for several days. In the second of these experiments, the atmosphere
remained absolutely unaffected, showing not only that it did not lose oxygen, but
that it also did not acquire carbon dioxide. In the first of these methods, however,
while the proportion of nitrogen and oxygen remained practically the same, the
carbon dioxide was diminished by absorption to the extent of about one half its
original volume. To this evidence of considerable absorption, it seems to me,
Baumert does not allow proper weight, when, by a more satisfactory method, he
subsequently finds what he believes to be the true composition of the emitted gas.

MUSEUM OF COMPAKATIVE ZOOLOGY. 21

the water of the river Seine contains oxygen and nitrogen in the pro-
portions determined by Humboldt et Provencal ('09), but that, owing
to the defective means of extracting the carbon dioxide employed by
them, they secured only one fortieth of the volume of that gas which
was actually present (Grehant, '69, p. 379).

Such being the case, it is evident that reliance cannot be placed on
Baumert's conclusions, for his opinion — that there was no perceptible
absorption of gases under the conditions of experimentation previously
detailed — rested ultimately upon his experiment with intestinal respi-
ration in distilled water, and his ability subsequently to extract the
whole of the gas absorbed by the water during the experimentation.

Being unwilling to sacrifice the limited number of young fishes in my
possession for the purpose of securing the contents of the air-bladder,
and not having the opportunity of getting the gas from the air-bladder
of adults, I determined to employ a method which seemed likely to
furnish positive evidence of the presence of carbon dioxide, if any were
really eliminated, even though it would not give a rigid quantitative test.

The plan was, to place the fishes in a vessel of water having a limited
air-chamber, which could be rapidly swept of its contents by a con-
tinuous flow of pure air through it, and to lead the air, thus drawn
from the experimental jar, through baryta water, which would indicate
the presence of even a small amount of carbon dioxide by the formation
of a precipitate.

Accordingly, a glass jar (Figure 2, j) of about 20 litres' capacity, pro-
vided with a thick ground-glass cover having a central neck and orifice
for a stopper, was selected. The cover was larded t© secure a close
joint, and in addition the edge was sealed with melted paraffine, and
the jar nearly filled with recently boiled distilled water. This was
siphoned into the jar with as much precaution as possible in order to
prevent exposure to the atmosphere. To make the water habitable for
the fishes, it was of course necessary to aerate it, and it was at the same
time important not to introduce in this process any carbon dioxide. To
accomplish this successfully was found to be a task much more labori-
ous than was at first anticipated. The apparatus shown in Figure 2
was that which finally proved satisfactory.

A Bunsen pump (p) attached to the hydrant provided the suction
required, and the system of tubes and chambers through which the air
was drawn was arranged as follows. Four glass combustion tubes (k)
each about 2 meters long and 2 cm. in diameter were loosely filled with
fragments of potassic hydrate, and joined by short pieces of rubber

22

BULLETIN OF THE

a
c

MUSEUM OF COMPARATIVE ZOOLOGY. 23

tubing, as indicated in the figure. After traversing these tubes, the air
was compelled to bubble through two sets of potash bulbs (k'), and
thence by a glass tube was led through the stopper of the experimental
jar (j). The glass tube was carried to within about 10 cm. of the bottom
of the jar, and, after describing a U-shaped bend, terminated in a plati-
num " rose " (r). Thence bubbling through the water, the air was led
from the air-chamber of the jar by a glass tube to the baryta bulb (b).
To guard against the effect of an accidental diminution of pressure in
the hydrant water, and a consequent reflow of water into the baryta
bulb, the latter was not directly connected with the pump, but an ordi-
nary Wolffs bottle (w) was interposed.

The preliminary test imposed upon the apparatus was, that it should
run twenty-four hours with no fishes in the water, but otherwise under
the same conditions that would be required when the fishes were intro-
duced, without giving a perceptible precipitate in the baryta bulb. It
required some time and considerable attention to details before this was
attained. All the connections were made by means of close-fitting rub-
ber tubing, which was made as limited as possible, narrow glass tubing
being used wherever practicable, and all the joints were in addition
sealed with melted paraffine. While the pump was in operation, the
water in the jar was of course under diminished pressure,1 the diminu-
tion being equivalent to a column of water equalling the distance be-
tween the surface of the water in the jar and the lower end of the bent
glass tube to which the "rose" was attached. Evidently the removal
of the stopper from the neck of the jar (through which it was proposed
to introduce the fishes) under such circumstances would allow the en-
trance of considerable impure air, which might give a precipitate as
soon as the pumping was resumed. To obviate this source of error, the
tubing of the apparatus was clamped at x, and by means of a hand
bellows air was injected through the potash system until equilibrium
was restored in the chamber of the jar, this being indicated when the
water rose inside the bent tube to the same height as outside. In the
preliminary test, this was done in the same manner as subsequently
when the fishes were introduced, and the stopper was also removed for
the length of time which experience had shown would be necessary for
the introduction of the fishes. Thus, as nearly as possible the same
conditions were observed in the preliminary and the final experiments.

1 It is to be observed that, so far as this diminution of pressure affects the
absorption of gases by the water, it can only act favorably in preventing such
absorption.

24 BULLETIN OF THE

When the preliminary experiment had proved that the air which for
twenty-four hours was being pumped through the apparatus did not
contain enough carbon dioxide to cause any trace of a precipitate in the
baryta bulb, then the tubing was clamped at x. Equilibrium was re-
stored by forcing in air as before, four fishes were introduced through the
neck in the cover to the jar, and the pumping was resumed. It was kept
up for six hours, at the end of which time not the slightest trace of a
precipitate had been formed, although the fishes had been emitting bub-
bles at the surface of the water in the ordinary manner during the whole
time. The baryta water was subsequently tested to make sure that no
error had been made in the matter of its sensitiveness to carbon dioxide.

The immediate inference from this experiment is, that the gas elimi-
nated by the fishes contained no trace of carbon dioxide; but here, again,
the possibility of an absorption of eliminated carbon dioxide by the water
cannot be rigidly excluded.1 It seems highly improbable, however, that
with an air-chamber which required at most only a few minutes to be
swept of its contents, there could have been a sufficiently prolonged
exposure of the gas to allow the absorption of its carbon dioxide. It
might be urged that this, being but a single experiment, can be entitled to
little weight, — that, even if in this one instance there was no elimina-
tion of carbon dioxide, it is to be considered simply as an exceptional in-
dividual 'nse. It is, however, to be borne in mind that there were four
fishes under experimentation, and that in the case of the analysis which
failed to show the presence of carbon dioxide there were six.

As the result, then, of these various experiments to determine
whether carbon dioxide is eliminated, it must be concluded for the
present, until opportunity is^ presented for a careful analysis of the
gas taken from the bladder without exposure to water, that the gas
of the air-bladder of Lepidosteus is not likely to contain more than two per
cent of carbon dioxide at the most, ivith a strong probability that in many
cases it does not contain an appreciable amount of that gas}

1 If this experiment were ever repeated, it is perhaps desirable that control
experiments should be carried on at the same time. In the control experiments
atmospheric air mixed with known volumes of carbon dioxide, varying from zero
to 2% of the total volume, should be made to bubble near the surface of the water.
By observing the frequency and estimating the volume of the gas emitted by the
fishes in a given time during the actual experiment, practically the same conditions
could be observed in the control experiments. The introduction of the carbon
dioxide mixture could easily be accomplished by means of a third glass tube,
piercing the rubber stopper of the jar and dipping just below the surface of the
water.

2 The recent analyses made by Jobert ('77 and '78a) on the gases taken from

MUSEUM OF COMPARATIVE ZOOLOGY. 25

But if little or no carbon dioxide is eliminated by the air-bladder,
what is the purpose of this aerial respiration] The answer must be
evident from the amount of oxygen which invariably disappears. The
emitted gas contains only from two thirds to one half the amount of
oxygen found in an equal volume of atmospheric air. I believe it is
therefore definitely and satisfactorily settled by these experiments, that
the air-bladder respiration in Lepidosteus is subservient to the oxygenation
of the blood.

There arise two more questions, which I believe to be intimately
related to each other. If the air-bladder does not provide for the
elimination of a larger amount of carbon dioxide than is stated, how is
this product disposed of] And, secondly, What is the relation between
branchial and aerial respiration in Lepidosteus, and how has it been
brought about ]

The most probable method of elimination of the carbon dioxide is by
means of the gills. To determine the question definitely would require
the complete separation of the effects of branchial respiration from those
accomplished by other means ; but it seems to me at present extremely
doubtful if any method can be devised which will enable one to do this
in the case of Lepidosteus. With Cobitis, or any other fish with intes-
tinal respiration in which the gas is emitted through the anus, the solu-
tion of the problem would be comparatively easy.

Bat there is already some evidence that the gills in such cases effect
an increased amount of elimination. At least the comparisons which
Baumert instituted between Tinea and Cyprinus on the one hand, and
Cobitis on the other, indicate clearly that there is a more rapid elimi-
nation of carbon dioxide through the gills in the latter case than in the
former.

If, then, it can ultimately be shown that in cases of aerial respiration
the gills accomplish most of the elimination of carbon dioxide, and that
the air-bladder is serviceable principally as a means of securing addi-
tional oxygen, something will have been accomplished toward appreciat-
ing the natural conditions which must have ted to the imposition of this

the air-bladder and from the intestines of several Brazilian fishes gave the
following results : —

I. Fishes with intestinal respiration,

a, emitting gas from the anus, Callichthys asper C. & Val. : 1.5-3.8% carb. diox.

b, emitting gas from the mouth and gill slits, Eypostomos : 1.5-2.8% carb. diox.

II. Fishes with air-bladder respiration, Erythrinus tcematus 1 . , o_9 aM v, jjox
Spix, or Erythrinus brasiliensis Spix, >

26 BULLETIN OF THE

function upon the alimentary canal, or one of its dependencies. The
water in which such fishes lived may have been at times incapable of
furnishing the necessary amount of oxygen, but sufficiently serviceable
as a means of removing, through the gills, the carbon dioxide. The
solubility of carbon dioxide in water, as compared with that of oxygen,
favors such an explanation.

I have not succeeded in finding many analyses of the gases held
in solution by water which seem capable of throwing light on this
question.

A. Morren ('41, pp. 471, 478-480, and '44, p. 12), who conducted
numerous experiments to ascertain the effect of light and of green or-
ganisms on the composition of the gases dissolved in water, has recorded
some interesting facts which seem to me to bear upon the problem. He
ascertained that when the per cent of oxygen in the gas extracted (by
boiling) from the water fell below 18, 19, or even 20, the fish contained
in his experimental reservoir began to languish, and many of them died.
He also deduced from his experiments these conclusions : that water
which [is stagnant or] flows slowly over a slimy bottom is subject to
conditions which serve to explain why it may be habitually less oxy-
genated than water which runs rapidly over a sandy bottom, and why
it undergoes greater variations in the composition of its dissolved
gases.

Morren also found that the oxygen in the gas contained in the waters
of the river Marne fell as low as 18 per cent on the 18th of June, 1835,
when there was a remarkable mortality among the fishes in the river,
and he ascribed this mortality to the want of oxygen in the water.

If such gas is incapable of supporting the life of fishes, it might occur
under certain circumstances that the proportion of oxygen would be
considerably below the normal 32 per cent, and still be far from pro-
ducing asphyxia. Under such conditions, which presumably happen
more often in the stagnant water of shaded swamps than elsewhere,
fishes which could avail themselves of the oxygen in the atmosphere
would be able to survive when others could not. They might still
employ their gills for the elimination of carbon dioxide into the water,
— 100 volumes of which can absorb about 120 volumes of the gas, —
but would have to depend largely upon the atmosphere for their supply
of oxygen.

One might conclude, then, that in the transfer of the respiratory
function from the gills to the prospective lungs the two components of
the respiratory process were separated from each other, and that the

MUSEUM OF COMPARATIVE ZOOLOGY. 27

oxygenating function was the one first to be transferred ; that, so long
as the animal lived in the water, the gills were, under all ordinary cir-
cumstances, the customary channel for the elimination of carbon dioxide ;
and that finally, during the passage from water to land, this function was
also imposed on the vesicular organ of the intestinal tract, which thus
became a lung in the fullest sense of the word.

IV. Embryology.

The interesting accounts of the ontogeny of Lepidosteus given by
A. A^assiz and by Balfour and Parker have put us in possession of
important data concerning vertebrate development. It is hoped that
a more extended study in this field will serve to answer some of the
questions left unsettled by them, and will afford additional results of
general value in discussions concerning the phylogeny of vertebrates.

There would be some advantages in beginning the subject of the
development of Lepidosteus with an account of the formation and
growth of the ova. Although I have considerable material for a study
of oogenesis, it has seemed to me better, on the whole, to defer a con-
sideration of the topic until the close of that part of these studies which
deals with organogeny, and to begin the description with the ovarian
ovum as it exists at the time of oviposition. But I have deviated from
the plan in the first part of the subject, — the egg membranes, — in
order to give a more complete exposition of the structures which
envelope the mature ovum.

1. Egg Membranes.

The only account of the structure of the egg membranes of Lepi-
dosteus is that given by Balfour and Parker ('81, p. 112, and '82,
p. 3G2 and foot-note).1 It is as follows : " They [the ova of Lepi-

i Ryder ('85, p. 146) has since given the following brief account : "In the ova of
Ganoids, Amia and Lepidosteus, the zona is composed, in the first instance at least,
of short, parallel, elastic fibers disposed in a plane vertical to that of the mem-
brane, these fibers being fused at their ends or just below the inner and outer
surfaces of the membrane. Sections through the egg membrane of Lepidosteus
seem to indicate the same condition of things as in Amia, in fact Dr. E. L. Mark
of Cambridge, Mass. has kindly shown me drawings which show the fibers of the
zona of the former isolated in the same condition as I have been able to separate
those forming the egg membrane of the latter."

It will be seen by the following description that I do not agree with all that

28 BULLETIN OF THE

dosteus] have a double investment consisting (1) of an outer covering
formed of elongated, highly refractive bodies, somewhat pyriform at
their outer ends (Plate 21, fig. 17,/. e.), which are probably metamor-
phosed follicular cells, and (2) of an inner membrane, divided into two
zones, viz. : an outer and thicker zone, which is radially striated, and
constitutes the zona radiata (z. r.), and an inner and narrow homo-
geneous zone (z. r.')." In a foot-note the authors state, in addition, that
" the ripe ova in the ovary have an investment of pyriform bodies
similar to those of the just laid ova," but that their attempts to ascer-
tain the nature of these peculiar pyriform bodies proved futile on
account of the bad state of preservation of the material at their
command.

A. Observations.

The observations which I have made on the egg membranes of Lepi-
dosteus will be followed by an historico-critical account of what is
known about the structure of egg membranes in other fishes.

I have examined the membranes in fresh eggs, as well as in those
which have been treated with various reagents, and have been able to
carry my investigation somewhat further than Balfour and Parker. It
will appear in the course of the following account to what extent my
results agree with theirs, and in what they differ.

a. Zona Radiata and Villous Layer.

Omitting for the present the modifications in the micropylar region
of the membranes, I will consider first the structure of the envelopes in
the recently laid egg which has not been subjected to the action of re-
agents, and subsequently will describe what is to be gained by the study
of sections made from eggs that have been hardened and stained. The
differences between the membranes of recently laid eggs and those of
mature ovarian eggs are so unimportant that it will not be necessary to
give a separate account of each. The nature of the differences, when
such exist, will be pointed out in the course of the description. When
the ripe eggs are artificially removed from the female by " stripping,"
they have at first irregular, more or less polyhedral forms, due to mutual
pressure in the ovary, and the membrane investing each is in a pliable
condition. This state is retained for a long time, provided the eggs do

Ryder here states. He seems to have entirely overlooked the existence of two
membranes, and gives such an account of his " zona " as to make me believe that
he has had in view what I have described as the villous layer.

MUSEUM OF COMPARATIVE ZOOLOGY. 29

not come in contact with water ; but when immersed in water they
soon exchange the flaccid for a more rigid condition, like the eggs of
many other fishes. Whether the egg is in water or in air, its surface is
excessively sticky, as Mr. S. Garman 1 has already accurately observed.
The eggs adhere equally well to polished and to roughened surfaces.
When let fall directly from the female into 95 per cent alcohol, with a
view to ascertaining if there was any special superimposed layer of viscid
substance such as that described by Kupffer ('78a, p. 178) for the
herring, the eggs have furnished no evidence of the existence of any
such continuous film, nor of any covering additional to that which is
distinguishable in the mature ovarian ovum, except small amber-colored
bodies mentioned later.

When laid the egg of Lepidosteus is enclosed in a single membranous
envelope about 50-60 //. thick (Plate I. Figs. 5, 11). This membrane is,
however, composed of two distinct but firmly united layers. The outer
layer, which embraces from one fourth to one third of the total thickness
of the membrane,2 I shall call the villous layer (st. vil.) ; the inner, the
zona radiata (z.r.). The former is the outer covering of "elongated,
highly refractive bodies," described by Balfour and Parker ; the latter
undoubtedly embraces both the zones — z.r. and z.r J — described by
those authors. It will be convenient to consider the two layers together
rather than separately.

Examined in the fresh condition, the outer surface of the egg envelope
is of a faintly yellowish or brownish tint, which is in part due to the
presence of small ovoid bodies of variable size, of an amber color and a
waxy appearance (Plate VIII. Fig. 5), which are scattered over the surface.
I am unable to say how or where these bodies are formed, but possibly
they result from the disintegration of the granulosa. Aside from these
bodies the surface presents a roughened or shagreen-like appearance,
which is found upon microscopic study to be due to slightly rounded
prominences of nearly uniform diameter which are separated from each
other by regular nearly straight lines, so that a view perpendicularly
upon the surface (Plate I. Fig. 1) presents a field divided by these lines
into small polygonal (four- to six-sided) nearly equal areas. The aver-
age size of the areas increases slightly as one approaches the vegetative
pole of the egg. When the envelope has been removed and torn

1 See A. Agassiz, '78a, p. 66.

2 Measurements of the fresh memhrane of an ovarian egg left twelve hours in
glycerine gave a total thickness of 68 fx, of which 50 /i represented the zona and 18 fi
the villous layer. After the addition of weak hydrochloric acid the latter increased
to twice its original thickness (36^).

30 BULLETIN OF THE

into pieces, it is readily seen to be composed of the two layers men-
tioned, which for the most part remain firmly united. Along the torn
edges, however, it often happens that the lines of rupture in the two
layers do not" coincide, so that for a considerable area there is a separa-
tion of one layer from the other (Plate I. Fig. 5). Such regions are the
most satisfactory ones for the separate study of the two structures.

Both layers, are translucent; to the outer belongs the brownish tint
seen in surface views, while the inner is slightly opalescent. When seen
from the edge or in optical section, or, better still, when cut with a
razor into thin radial sections, both exhibit radial striations, which are
much closer to each other in the inner layer than in the outer (Plate I.
Figs. 4, 5, 11).

Aside from certain exceptions which will be considered later, the fine ra-
diate markings of the inner layer, or zona, appear as nearly straight par-
allel lines, which are traceable through the whole thickness of the layer,
but which become gradually less prominent toward the deep surface.

The markings of the outer or villous layer, on the contrary, are less
uniform ; they traverse the whole thickness of the outer layer, but are
most clearly defined near the periphery, their deeper portions being
more irregular and confused, and often exhibiting a tendency to a zig-
zag course. They indicate the boundaries of highly refractive prismatic
bodies, of which the layer is composed, and which seen endwise produce
the appearance of polygonal areas already alluded to. When viewed
from its deep surface (compare Plate I. Figs. 2, 7), the villous layer
has a somewhat ragged appearance ; it also exhibits polygonal areas, but
they are less regular and less clearly defined than those seen from the
external surface. WThen the egg membrane has been left for some time
in water, or, better still, in a mixture of water and glycerine to which a
trace of hydrochloric acid has been added, the prismatic elements which
compose the villous layer undergo a remarkable change, during which
the cause of the peculiar zigzag appearance of their boundaries is made
evident. After a time the free rounded ends of some of the prisms
appear to protrude above the neighboring ones (Plate I. Fig. 4), thus
giving the surface a less even contour than it had at first. On com-
paring the conditions beforrf and after the application of acid, it at once
becomes apparent that the layer has increased in thickness. At its free
edges the prisms become more or less detached from each other, and it
then is possible to appreciate their real form.

There are recognizable at least three distinct regions in each prismatic
villus, and each may be roughly compared to a stalk of grain, with its

MUSEUM OF COMPARATIVE ZOOLOGY. 31

head, shaft, and root. These names may be applied not inappropriately
to the three regions of a villus. The peripheral portion or head (cap.),
embracing one fourth, or sometimes as much as one third, of the original
thickness of the layer, is distinctly prismatic and highly refractive ; its
sides are parallel, and it is little affected by the acid, so that, although it
increases very slightly in size, it -still retains to some extent its angular
form. Its free end is always more or less rounded (Plate I. Figs. 4, 9, i).
Following this terminal head, and marked off from it by a slight con-
striction, comes the stalk (Fig. 9, i, pd.), a long, also prismatic fibre,
which is less highly refractive than the head, and is so crowded as to be
folded back and forth, thus giving to it the appearance of a spiral spring.
In fact, many of the fibres are coiled into a tolerably regular spiral, but
the majority are simply folded irregularly, evidently being accommo-
dated to the space most available.

Through the action of acid these stalks begin to swell, and some of
them — since they are affected more promptly than others — cause an
earlier protrusion of the corresponding prismatic heads (Plate I. Fig. 4).
The increase in the thickness of the layer — which soon reaches twice
its original dimensions — is due almost entirely to the swelling of these
deeper portions of the villi. When isolated, they may in some cases be
elongated to ten or twelve times the length of the coils which they at
first formed (a, b, Fig. 9, Plate I.). A portion of this elongation is due
simply to the unfolding of the compressed stalks ; but ultimately in
proportion as it elongates the stalk becomes more attenuated. It often
happens in this process that different portions of the stalk are at first
unequally affected. Usually it is the deeper portion which is first to
uncoil and to become attenuated (n, Fig. 9). When fully extended the
stalk is slightly tapering, being narrowest at a little distance from its
basal or root end, and although generally quite uniform in calibre, it
occasionally exhibits varicosities. In many cases the isolated villi (Fig.
9, g, h) appear as though temporarily prevented from straightening out
because of delicate longitudinal structures of a band-like appearance.
The aspect of the stalk is then remarkably similar to the pouched con-
dition of the mammalian colon, to the longitudinal muscles of which
these band-like structures correspond. The apparent " bagging " is
usually all in one direction, namely, toward the attached end of the
villus (h, Fig. 9). The basal end or root {rx.) appears to terminate
regularly in a number (3-9) of tapering root-like diverging prolonga-
tions (Fig. 9, /, g, i, Jc), which are often apparently connected with each
other by membranous expansions of the basal portion of the villus.

32 BULLETIN OF THE

These roots serve to fasten the villous layer very firmly fo the zona
radiata, in a manner to be explained in connection with the account of
that layer.

The much finer radial markings ot tne zona radiata (z. r.) are entirely
different in character from those of the villous layer ; seen from either
surface with a moderately high power -they appear as punctations, dark
or light according to the focusing (Figs. 3, 8, Plate I.), evenly scattered
over the surface, and yet so arranged as to give the whole area a very
characteristic appearance. Although rather evenly distributed, they are
arranged in groups or systems. One may trace over a considerable area
a series of dots placed at the intersections of a system of imaginary equi-
distant lines crossing each other at right angles ; near by may be other
series, in which the systems of imaginary lines cross at angles varying
widely from that of 90°; in still other series, the lines are arcs of circles ;
the circles may vary somewhat in size, but the arcs are never to be
traced for more than a few degrees. These different systems abut upon
each other in the most fortuitous manner, and the intervening spaces are
filled with dots so evenly arranged as not to interfere with a fairly uni-
form distribution over the whole surface (compare Plate III. Fig. 5).
Higher powers show that the punctations are circular in outline, of very
nearly equal diameters (0.5 jj. at their outer ends), and placed at inter-
vals averaging about 1.5 fi. My notes of May 24 and 25, 1883, make
the intervals between the pore-canals, as determined by measurements
on the shell of an ovarian egg that had lain in glycerine over night,
only | fx, less than half the value given above ; but I believe that the
larger distance fairly represents the average condition.

Thin tangential sections show by focusing that these markings are
due to minute canals (pore-canals), which are ordinarily hollow, or at
least contain a substance that is less refractive than the common homo-
geneous mass of the matrix which they traverse. I have not seen any
evidence of a differentiation in the optical properties of the walls of these
pore canals which would allow one to speak of them as tubules.

Weak hydrochloric acid causes the zona to swell slightly, and ulti-
mately renders the pore-canals less conspicuous or entirely invisible.
There are certain of them which do not fade away, however, even after
treatment with acid, and which at length become the only visible struc-
tures in what otherwise appears as a homogeneous layer. (Fig. 10.
Compare also Figs. 4, 6.) These canals very generally have a spiral
course, and are noticeably broader at the outer surface of the zona than
elsewhere ; they taper gradually toward the inner surface of the layer,

MUSEUM OF COMPARATIVE ZOOLOGY. 33

I it seldom reach it ; most of them are traceable only a short distance
from the outer surface. They owe their prominence to the fact that
they are filled with a highly refractive substance having the form of a
corkscrew. When the villous layer has been torn from the zona, this
substance appears to terminate exteriorly in a ragged, broken end, which
in some instances is drawn out into a tapering appendage (Fig. 10, a).
There can be no doubt — according to evidence to be gained from
ovarian eggs — that this substance is continuous with that of the pris-
matic columns of the villous layer, of which they are in reality the roots.
The roughened appearance of the inner surface of the separated villous
layer is largely due both to the lacerated ends of these roots and to the
fact that many of them are wholly withdrawn from the pore-canals when
the two layers are torn asunder. This relationship of the layers also
explains why it is so difficult to separate them over even a limited area.
Sections of stained eggs, both radial and tangential, give instructive
views of the egg membranes. In radial sections the difference between
the villous layer and the zona becomes at once apparent from the deeper
stain which the former takes on. The pore-canals are also usually more
distinct -than in the fresh egg, although the effect of certain acid pre-
servative reagents (Perenyi's fluid, picrosulphuric mixture) is such as to
obscure the radial markings of the zona. In the villous layer a still
more striking contrast is produced between the heads and the stalks of
the villi, since the former almost invariably take a much deeper stain
than the latter. Especially is this true when stained in picrocarmine,
by which the heads are colored a deep carmine while the stalks and roots
remain unstained or take a greenish-yellow hue from the action of the
picric acid (compare Plate IV. Fig. 1). In borax carmine both portions
are usually stained, and almost invariably the head much deeper than the
rest of the villus ; but it has occasionally happened that the heads were
less deeply colored, and presented a slightly yellowish tint (Plate IX.
Fig. 2). I am unable to account for the difference, unless possibly a
prolonged decoloration in hydrochloric acid is the cause of the feeble
stain of the head ends. In all these stained radial sections it is to be
seen that the transition from the head to the stalk, although not marked
by a sharply defined line, is nevertheless abrupt. Owing to this, and
the fact that the stalks, as well as the heads, are of nearly uniform
lengths, radial sections of well stained specimens always exhibit the
stalks in the form of a broad band or zone, sharply marked upon both
edges, — more deeply stained than the zona radiata, but less deeply
than the narrower well defined band which is made up of the heads of

VOL. XIX. — NO. 1. 3

34 BULLETIN OF THE

the villi. Each of the heads has its external free surface more or less
rounded and not quite smooth, its sides nearly parallel and straight,
and its ill-defined deep face also tolerably straight. Along the last it
is distinguishable from the stalk, with which it is continuous, by its
greater refractive power as well as deeper color, and by a slight dimi-
nution in the size of the stalk. The last distinction becomes more
conspicuous t^.e more the stalk is elongated. The differences between
head and stalk are emphasized by the fact that the villi have a greater
tendency to rupture along this line of union than elsewhere (Plate II.
Fig. 1, and Plate III. Fig. 1). The outlines of the free end and the sides
of the head are sharp, and in thin sections, especially such as cut the
heads crosswise, the margins seem to be limited by a narrow double-
bordered dark band (compare Plate III. Fig. 3), as though the head were
invested in a thick deeply staining membrane. Since I have never been
able to find evidence of the separation of any membranous structure
from the surface of the head, I am disposed to believe that the appear-
ance simply results from a differentiation of the cortical portion of the
head, which otherwise appears perfectly homogeneous. In some cases
this cap-like cortical part seems to exert a restraining influence on the
swelling of the central portion ; at least I interpret in that sense certain
conditions of the heads frequently met with. In such cases their sides
are not strictly parallel, especially when the villi stand in an isolated
position (Plate II. Fig. 1). The head, instead of being marked off from
the stalk by a constriction or shoulder of the ordinary form, has its
outline gradually broadened or flaring as it approaches the peripheral
end of the stalk, and its cap-like sheath appears to end abruptly with
edges which are slightly everted ; the connecting portion of the stalk is
as broad as, or even broader than, the basal end of the head, so that the
direction of the resulting shoulder is just the reverse of that commonly
seen. The most natural explanation of this appearance which occurs to
me is, that the free edge of the cap-like sheath is distended, and even
sometimes everted, by the swelling which takes place in the region
where head and stalk are continuous, and that the sheath in all probabil-
ity acts as a restraining investment in preventing any great distention
in the rest of the head.

The stalks, in radial sections of eggs which have been subjected for
some time to the action of water before hardening, have the appearance
of comparatively slender columns, which are often slightly sinuous, but
in general nearly parallel. They taper at first quite rapidly for a short
distance from the head, and then only very gradually toward the basal

MUSEUM OF COMPARATIVE ZOOLOGY. 35

or root end. The spaces between the stalks are much greater than those
between the heads ; while the latter sometimes remain — even after the
prolonged action of water — in a continuous layer, the stalks often
appear to stand individually isolated. It is more common, however, to
find, as the result of the swelling, that both the heads and the stalks are
arranged in groups or patches, — better shown in tangential sections.
Even when the heads are not thus separated, the stalks may be gathered
into clusters which leave in radial sections broad lenticular spaces be-
tween them (Plate III. Fig. 1).

The stalk gradually diminishes in size to near it3 zonal end, where it
enlarges rather promptly into a sort of conical foot, which exhibits dark
longitudinal or radiating markings continuous with the dark outer ends
of corresponding pore-canals in the zona. In some cases the foot is
split into two or three strands, between which there is then left a space
that in radial sections is triangular, with its base resting on the zona
and its more acute angle rising into the stalk. The roots proper embrace
only the portions of the villi still occupying the pore-canals of the zona.
In some cases they are to be recognized as occupying every pore-canal,
in others some of the canals appear to be destitute of villous contents.
The roots are highly refractive, like the stalk, and seem to stain even
more deeply than the latter. They are always broadest at the outer
end, and taper until they are exceedingly fine threads. They seldom
reach more than a tenth or an eighth of the way through the zona,
although longer and larger roots are met with at intervals. They
always appear more tortuous — zigzag, or spiral — than the pore-canals
which do not contain roots, and are at times so irregular in form as to
have caused great distortions in the canals (Plate IX. Fig. 2). Their
finest tips, however, always appear continuous with the much more
faintly marked pore-canals. I cannot doubt, therefore, that they are
accommodated by simple enlargements of the pore-canals. The great
regularity in their distribution, too, allows no other interpretation than
that the position of the roots is practically determined by that of the
pore-canals.

Tangential sections of stained eggs (Plate III. Figs. 2-5) afford the most
satisfactory evidence of the shape and grouping of both heads and stalks,
and is the only safe means of controlling the views of the foot region
gained by radial sections. The heads are at first close set, leaving only
the finest narrow lines, with here and there an irregular opening where
the prisms incompletely match (Plate III. Fig. 2) ; their cross sections are
angular and range from variously proportioned triangles to six- or seven-

Q

6 BULLETIN OF THE

sided polygons. After the prolonged action of water they become less
angular, and begin to separate along irregular lines, so as to leave the
heads arranged — as already indicated — in patches, which vary con-
siderably in size but are for the most part of a characteristic polygonal
outline, with borders which are necessarily jagged owing to the nature
of the lines of separation, for the latter never split a prism, but simply
separate adjacent ones. The heads may vary in diameter in the ratio
of one to two.

The dark border already alluded to is best seen in thin tangential
sections (Plate III. Fig. 3), and is readily distinguishable on all the
heads when well stained and cut sufficiently thin. The line of separa-
tion between prisms is not always distinguishable, but whether this is
due to actual contact or not it is difficult to say, since the least obliquity
in the section is sufficient to obscure so faint a markine;.

The stalks also are found upon cross section to be prismatic, even
after the process of swelling has completely isolated them (Plate III.
Fig. I). They are also arranged in groups which correspond fairly to
those of the heads, but the spaces between them are much greater.
Occasionally sections of stalks are to be seen, even from the middle of
the stalk-zone, the central part of which has not been stained (Plate
III. Fig. 4, a, a). Careful examination shows that such stalks are really
hollow, the boundary of the colorless area being sharply defined. I have
never seen vacuoles in the middle region of any of the stalks examined
in radial section ; besides, these cavities can often be traced continuously
on successive tangential sections toward the foot. They are, m6reover,
increasingly frequent as one approaches the zonal attachment of the
stalks. The consideration of all these facts makes me quite sure that
many of the stalks, at least in their basal halves, are really hollow
prisms, although I have never been perfectly certain that I have seen
this condition in radial sections. One may, however, as before stated,
readily see on radial sections that the expanded foot of the stalk is often
apparently split into diverging roots, and that there is an intervening
unstained region. The prolongation of this space, which is triangular
in side view, forms, I believe, the cavity of the stalks in question. Al-
though the prisms appear sharply marked in cross sections, there is very
generally a trace of a filmy substance projecting here and there from
their edges in the form of faintly marked threads, which sometimes end in-
definitely in the inter-prismatic spaces, but at other times appear loosely
to connect neighboring stalks (Plate III. Fig. 4, /3). This substance
seems to stain less deeply than the stalks themselves, but it is exceed-

MUSEUM OF COMPARATIVE ZOOLOGY. 37

ingly difficult to decide whether the faintness of color is due to a specific
difference of substance, or is simply the result of the tenuity of the film
itself. In the former case, one would perhaps be justified in concluding
that there was an inter-prismatic substance which served the purpose of
a cement to hold the stalks together. The peculiar longitudinal band-
like structures noticed during the elongation of the stalks (Plate I. Fig. 9,
g, h, I) are possibly to be referred to the same substance.1 But on the
second assumption these shreds of faintly stained substance could be
hardly more than the lacerated edges of the stalks themselves. I con-
sider the latter the more probable explanation.

Owing to the spherical form of the egg, tangential sections are circular
in outline, and in a given section the centre represents the deepest part.
When the centre of such a section is occupied by the superficial part
of the zona radiata, the periphery is formed by a circular band of the
villous layer, the deeper portions of which are nearer the centre of the
section.

A segment from that portion of the band which cuts through the
bases of the villi, their roots, and the superficial portion of the zona, is
shown in Plate III. Fig. 5. Proceeding from the outer (in the figure
upper) toward the central portion of the section, one observes that the
cross sections of the villi increase somewhat in size, that the stalks
which embrace cavities become more numerous, and that the outlines
of the stalks become more and more star-shaped, and then irregular,
and that finally they break up into detached spots, which a little farther
along become smaller and smaller until they cannot be distinguished in
size from the pore-canals.

Since the sections of the membrane are successively increasing in
diameter, the deep face of each will pass through a broader portion of
the zona than the upper face will. If for the purpose of examination
the section be inverted, so that the deep face is uppermost, the relation
of parts can be much more easily and satisfactorily studied than if it be
viewed from the upper face only, because the zona offers less impediment
to vision than the thick-set columns of the villous layer. Attentive
focusing shows conclusively on such preparations that the rays or
branching roots of the prismatic columns lead each to a pore-canal, and
it becomes possible in many cases to note the exact number of pore-

1 Dilute hydrochloric acid causes the distance hetween the heads of the villi to
increase. This would be readily explainable as the result of the swelling of an
inter-villous substance, could the existence of such a substance be satisfactorily
established.

38 BULLETIN OF THE

canals in which a given stalk takes root. The substance of the roots
and of their rib-like extensions up the stalk appears to be more deeply
stained than that of the expanded foot of the stalk; but this is perhaps
only an appearance due to the fact that they are considerably thicker
than the membranous portion which connects them.

As the successive sections pass through deeper and deeper poi'tions of
the zona radiata, the calibre of the pore-canals grows very gradually
finer, and those which are plugged with deeply stained villous roots
become less numerous, but otherwise there is no essential difference
in the appearance of the sections. The characteristic arrangement of
the pore-canals previously described is visible here, and may' be made
out more easily than on the fresh egg-shell, provided the sections are
made perpendicular to the canals and are sufficiently thin.

In radial sections from eggs that have been hardened and stained, the
zona is usually of a uniform faint tint (Plate III. Fig. 1), but often
there is a very gradual deepening in the intensity of the color in passing
from the outer to the inner boundary of the layer (Plate II. Fig. 1). In
a few instances this deeper stain seems to extend toward the outer sur-
face of the zona in flame-like jets (Plate IV. Fig. 1). The outer boun-
dary of the zona, although appearing slightly irregular, owing to the
variable lengths of the root-like prolongations of the villous layer, is in
reality fairly even and sharply marked (Plate II. Figs. 1, 7, 8, Plate
III. Fig. 1, and Plate IV. Fig. 1). The inner boundary is still more
precisely defined, and appears as a fine continuous line, which sharply
separates the zona from the peripheral layer of the yolk. Nowhere is
there any evidence of a gradual transition from the yolk to the mem-
brane. Occasionally, when the section is not exactly perpendicular to
the inner surface of the zona, this boundary appears double, but careful
focusing in such cases always shows this to be an optical illusion. In
a few instances I have seen a similar appearance which was not thus
explainable. For a considerable distance a layer of nearly uniform
thickness appeared to intervene between the zona radiata and the yolk
(Plate II. Fig. 7). But the line which separated this from the rest of
the zona was never to be made out for more than a small portion of the
circumference of a section, for it either terminated abruptly, or, gradu-
ally approaching the inner boundary of the zona, became confluent with
it. Its inconstancy and its want of continuity are together sufficient to
show that the layer in question is not entitled to be considered a dis-
tinct membrane, nor even a differentiated portion of the zona radiata.
I may add, that I have never seen a section of this kind in which it was

MUSEUM OF COMPARATIVE ZOOLOGY. 39

not possible to discover in some part of the layer evidences of pore-
canals continuous with those of the remaining portion of the zona
radiata. I am therefore convinced that the zona radiata is a single
homogeneous layer which is in direct contact with the surface of the yolk,
and is traversed by pore-canals which reach from the yolk to its outer
surface.

When radial sections of the zona are broken, they occasionally show a
tendency to rupture in lines concentric with the surface of the egg, but
this is so rarely the case as hardly to be characteristic. The fracture is
usually irregular, and not dependent on any structural feature ; even
the pore-canals do not appear to have much influence on the direction
of the line of separation. The nature of these canals can be more readily
studied on sections of hardened specimens than on the fresh shell. Their
proximity to each other is not so readily determined from radial sections
as by means of the tangential sections already described. The same
general features which were mentioned in describing their appearance
on the fresh egg are usually visible with even greater clearness on those
which have been hardened. The distinctness of the pore-canals varies,
however, considerably in different specimens, depending undoubtedly
upon the refractive power of the mounting medium, which penetrates
the canals, as compared with that of the matrix of the zona itself.
Upon the most favorable preparations the canals can be easily traced
from end to end, so straight is their general course. At the periphery
of the zona they are uniformly somewhat broader than at its deep sur-
face ; but they taper so gradually as to make the difference in calibre,
even at their two ends, trifling. In the case of almost every canal a
slightly spiral course is noticeable near the outer end, whether it be
plugged with the root of a villus or not ; and throughout the whole
length there is usually the faintest trace of a wavy or zigzag course.
Aside from this, however, the canals are remarkably straight and paral-
lel. There are no enlargements or irregularities in the calibre, save
those which appear to result from the distention of the canal with the
substance of the villous roots already described.

There still remain to be considered some peculiarities of the villous
layer, which either result from particular methods of treatment, or have
not been observed sufficiently often to allow one to consider them
characteristic features.

Of those dyes which I have used, acetic acid carmine gives the sharp-
est differential staining for the heads of the villi. While the stalks
and roots remain comparatively pale, the heads (Plate II. Fig. 2) take a

40 BULLETIN OF THE

deep rose tint, and the transition from the substance of the head to
that of the stalk is rather abrupt. It happened that many of the villi
from the shell of a mature egg, that was let fall into ninety per cent
alcohol without contact with water, and was afterward stained for twelve
hours in acetic acid carmine, exhibited a very peculiar appearance at
the free surface of their heads. At or very near the middle of this
surface the dark border, so characteristic of the heads of the villi, seems
to be interrupted, aud there projects from the free end of the head a
short conical or longer finger-like process. This issues from the head,
apparently through a circumscribed opening in the cortical layer, and
may assume a variety of forms, several of which are shown in Plate II.
Fig. 2, a-m. This peculiarity is interesting, as showing that there is
a region of least resistance in the cortical layer near the apex of each
head, which allows the protrusion of a part of the substance of the head
when it is subjected to the swelling influence of the acetic acid ; but
whether this fact is capable of throwing any light on the source of this
villous layer, or the method of its formation, I greatly doubt.

There is often to be seen in radial sections of the villous layer a
strong tendency for the villi to fuse (Plate II. Fig. 2, I). This is
especially true of the region of the stalks, although it is also to be
observed among the heads. Since this tendency seems to be much
greater in some cases than in others, I am induced to believe that it is
due to the influence of the reagent with which the egg was hardened,
and sometimes perhaps is dependent on the length of time the egg has
been in the water before hardening.

In a few cases — especially in certain nearly mature ovarian eggs
which were hardened in chromic acid — I have seen peculiar markings
in the villi, which at first led me to think they might be traversed by
spaces analogous to the pore-canals of the zona. They were first noticed
on tangential sections, and appeared there like minute circular holes in
the segments of the prismatic villi (Plate II. Figs. 4, 5). Focusing
showed that their contents were much less refractive than the substance
of the villi, and they were consequently very sharply defined. But the
notion that they were optical sections of tubes, like pore-canals, was at
once corrected upon finding isolated villi, which had fallen out of the
layer and were seen sidewise. When the thickness of the section is
about equal to the diameter of the villi, it is difficult, if not impossible,
to decide whether the isolated angular blocks are seen endwise or side-
wise ; but by selecting the thicker sections, where the length of thf
villous segments is greater than their diameter, the difficulty is avoided

MUSEUM OF COMPARATIVE ZOOLOGY. 41

and it at once becomes evident that the spaces supposed to be canals
are for the most part minute spheroidal cavities or vacuoles. Usually
there is only a single vacuole in a villus, although occasionally two are
to be seen in the same cross section (Plate II. Fig. 4). Not all of the
villi contain these cavities. Taking into the account their abundance on
successive sections from the villous layer, I should estimate that not
more than one half or three quarters of them present this feature. The
proportion to be seen upon a single section is, of course, much less than
this. They are most abundant in the stalks, but occasionally one is
also seen in the head. Upon the egg, where they were found most
abundantly, they were rather more numerous in the micropylar region
than at the opposite pole. In the latter region there were, however,
sometimes as many as three or four in one villus, although the size (0.5
to 1 /a) was the same as at the micropylar pole. I have in a few cases
observed that the vacuoles were elongated, and then they were always
of uniform calibre and were curved. Occasionally (Plate II. Fig. 4) such
a tubular vacuole appears to communicate at one end with the inter-
villous spaces. Concerning the nature of the contents of these vacuoles,
I can only say that they do not stain, and do not appear differently
from what one would expect if they were cavities simply filled with the
mounting medium.

The differences between the membranes in mature ovarian eggs and
those recently deposited are principally the result of the swelling of the
layers by the water, and do not require any further explanation.

The foregoing account of the zona radiata in Lepidosteus contains
descriptions of two features which appear to me to bear directly on the
condition of the zona radiata of fishes in general.

First. The proof that the striate appearance of the zona is due to
pore-canals, although very generally assented to by the most competent
observers, especially in recent years, has nevertheless hitherto rested
upon comparatively slight evidence. That this evidence has been
meagre depends upon the excessive minuteness of the structures in
question. It is not to be overlooked, in the first place, that the tubu-
lar nature of the pore-canals in the case of the perch, as originally de-
scribed by Johannes Miiller ('54) for what he called the "Eikapsel,"
has not the slightest bearing upon the nature of the pore-canals of the
zona radiata, since the egg capsule of Miiller is a structure entirely
different from the zona. I cannot, however, avoid the conviction that
his opinion as to the tubulated condition of that capsule has had con-

42 BULLETIN OF THE

siderable influence in effecting the general acceptance of similar conclu-
sions as to the nature of the radiate markings of the zona. Neither the
evidence produced by Midler, — the possibility of pressing yolk globules
through the " pore-canals " of the capsule, — nor the vacuolated condi-
tion described by Ransom ('68, p. 455), can have any direct bearing on
this question.

Leuckart ('55, p. 258) appears to have been the first to assert with
the utmost poSitiveness that the radial striations of the zona were due
to pore-canals ; and although he nowhere states the exact nature of
the evidence which convinced him, we are doubtless at liberty to infer
that it was, in part at least, the kind of evidence which he elsewhere
('55, p. 106, foot-note) makes use of; namely, the now well understood
differences in optical effects produced by elevations and by depressions
of surfaces. Kblliker ('58, p. 83) soon furnished additional evidence,
derived partly from the study of thin sections of the zona in the trout,
but more especially, as it appears to me, from the fact that maceration
in fresh water causes the middle region of these supposed pore-canals to
be converted into vacuoles. Aside from the arrangement of the dot-like
appearances as seen from the sm'face of the zona, which has been very
generally recognized, and the features emphasized by Leuckart and
Kolliker, I am not aware that any additional evidence in proof of the
nature of the pore-canals has yet been produced. If, then, the facts
warrant the description I have given of the zona in Lepidosteus, the
evidence that it is a canaliculation which produces the radial striate
markings in the zona radiata of fishes' eggs has received an additional
confirmation.

Secondly. Although Miiller (as well as more recent observers) has
shown that the pore-canals in the outer envelope, or capsule, in the
case of the perch may have a spiral course, no one has hitherto observed
a similar feature in the case of the canals of the true zona radiata.
The natural injection of these canals in Lepidosteus with a substance
continuous with that which constitutes the villous layer, renders it
comparatively easy to establish the spiral course of the canals in that
fish ; and this makes probable the inference, that certain irregularities
in the direction of these canals, shown by other observers to exist in
the case of other fishes, may in reality be referable to the same
spiral condition, which, from the minuteness of the canals, has not
been recognized.

MUSEUM OF COMPARATIVE ZOOLOGY. 43

b. Micropyle.

The micropyle was apparently overlooked by Balfour and Parker,
since it is not mentioned by them ; nor has it been mentioned, I believe,
by any one else, although it occupies a region which is so conspicuously
marked that, having once seen it, one could readily find it with the aid
of a simple lens. Except in eggs that have lain for some time in water,
the region of the micropyle appears, when seen under a hand lens, like
a minute hole in the shell ; in surface views with a higher power it looks
like a deep circular pit (Plate IV. Figs. 3, 4) sunk in the egg membrane.
Its diameter is five or six hundredths of a millimeter. Its outline is
nearly always circular, and it has a clearly cut edge. In a few cases a
cross section of the pit has pi'oved to be oval instead of circular, occasion-
ally with one diameter of the oval more than twice as long as the other
(Plate VII. Fig. 4). A similar appearance, though not so marked, is often
produced, even when the pit is really circular, if the plane of the section
is oblique to its axis. Sometimes the pit is partly filled by a whitish, ap-
parently spheroidal body (Plate IV. Fig. 4). When the egg is so viewed
that this depression lies in the equator, the profile of the egg in its vicinity
may be slightly modified, and show a low conical elevation, at the apex of
which the pit is located. This is not commonly the case, however, for
usually there is nothing in the profile to denote the position of the pit.
In eggs nearly mature, and in those which have been recently laid, its
place can be easily found by its relation to the lighter colored animal
pole of the egg. It is invariably located over some part of the germinal
area, and usually precisely over its centre (Plate IV. Fig. 3).

The real nature of this pit and its relations to the two layers of the
egg membrane and to the yolk can be studied on optical, but still better
on actual sections. For a general survey radial sections are most in-
structive, but for the elucidation of some questions sections tangential
to the egg at the animal pole are more valuable.

In strictly radial sections through the region of the micropyle, it is
to be seen that the surface of the egg is deeply depressed. The form of
the depression varies somewhat in different eggs, from that of a funnel,
i.e. with sloping walls (Plate IV. Figs. 1, 5), to that in which the walls
are for some distance almost parallel (Plate V. Fig. 2). This depression
results from an infolding of both layers of the egg membrane ; it forr.ts,
however, only an approach to the true micropyle, or micropylar canal,
the latter being a minute passage through both layers which begins at
the bottom of the depression.

44 BULLETIN OF THE

The funnel, as I shall call that portion of the egg membrane which
forms the walls of the depression, involves a modification of both the
zona radiata and the villous layer. Both are affected in two ways, in
thickness and in direction.

The villous layer begins to grow thinner at some distance from the
edge of the funnel. Sometimes it retains its normal thickness to within
a distance equal to the diameter of the funnel : at other times it begins
to grow thinner at three or four times that distance from the pit. Its
diminution in thickness is quite gradual and very nearly uniform until
it reaches a minimum at the micropylar canal. The stalks of the villi
are shortened more than the heads, in comparison with their appearance
on other parts of the capsule, and the boundaries between them grad-
ually become less distinct. The diameter of the villi also decreases
considerably. Near the bottom of the funnel they become very short,
but frequently it is evident that, instead of constantly diminishing in
diameter, they may even increase as compared with other regions of
the funnel (Plate VI. Figs. 5-8).

In all parts of the funnel the villi retain a direction perpendicular to
the outer surface of the zona. In the lateral wall, and especially near
the bottom of it, they are slightly wedge-shaped or conical, the head
ends being narrower than the root ends. They thus accommodate them-
selves to the diminished space at their disposal (Plate VI. Figs. G-8).

The zona radiata (Plate IV. Fig. 1) likewise begins to diminish in
thickness at some distance from the micropylar canal, and continues to
do so until it reaches the canal ; but it does not, like the villous layer,
grow thinner at a uniform rate. Its thickness decreases very slowly to
within a short distance of the region where the membranes begin to bend
inward to form the funnel, and then it suddenly narrows to one third its
normal dimension, after which it again decreases more slowly until it
reaches the micropylar canal. The pore-canals are not perceptibly finer
nor more closely set in the vicinity of the micropyle than elsewhere. They
retain in most regions a rectilinear course perpendicular to the surface
of the zona, but at the region of most rapid reduction in the thickness
of the latter, and for a little distance on either side of it, their course
is curved, the concave side facing the micropylar canal.

The change in the direction of the two layers of the egg-shell results
in the formation of an external depression, which is considerably deeper
than the total thickness of the shell, so that, even with a great diminu-
tion in the thickness of the latter, its inner surface projects into the
yolk as a conical elevation, which is nearly as high as the thickness of

MUSEUM OF COMPARATIVE ZOOLOGY. 45

the shell. la this deflection of the membranes, the zona radiata seems
to bend more abruptly than the villous layer ; this, however, is due
principally to the fact that the region of greatest curvature is also the
region of most rapid change in the thickness of the zona. From this it
results that the inner contour of the zona is much more abruptly curved
than the outer, in some cases appearing almost angular. As a further
consequence of this, the conical elevation appears to arise abruptly from
the inner surface of the membrane ; its apex is rounded, and in the
ovarian egg its surface is everywhere in contact with the yolk. An
inquiry as to whether this infolding is the result of a process of absorp-
tion, or is due to a peculiar local modification of the activities which
produce the membrane, will best be deferred until I have given a de-
scription of the layer of cells which immediately invests the ovarian
ovum.

The micropyle proper, or the micropylar canal (Plate I. Fig. lla,
Plate IV. Fig. 1, Plate VI. Figs. 3, 4), is straight and of uniform calibre.
It begins at the centre of the bottom of the funnel, and passes through
both villous and zonal layers of the egg membrane ; it is about 8/x long.
Its cross section is circular and about 2 ll in diameter. There is no flare
to the canal, either at the external or internal end, so far as I have been
able to observe. I am unable to say whether the diameter which I have
given is that which the micropyle possesses at the moment the egg is
laid. From measurements of spermatozoa allowed to dry upon the slide
(Plate VII. Fig. 3), 'one would imagine that the calibre of the micro-
pylar canal must be at least 3 jx, that being the diameter of the heads of
spermatozoa thus treated ; but according to measurements made upon
living spermatic cells the heads are only about 1.8 ll in diameter, so
that I think 2 /x is pi'obably the normal average calibre of the canal.
Still, I have sections in which its diameter is 2.5 /a, and in the case of
some fresh membranes it was only 1.5 fi in diameter. The narrowness
in the latter case I attribute to the swelling of the zona when exposed
to water and glycerine, in which the membranes were examined.

c. Granulosa.

Nearly mature ovarian eggs are' closely enveloped by an uninterrupted
cell layer, which is everywhere in contact with the outer surface of the
villi. Over the greater part of the egg this layer — the follicular epithe-
lium or granulosa — is composed of thin, flat polygonal cells, arranged in
a sheet only one cell thick. In surface views the granulosa cells (Plate V.
Fig. 4) appear of fairly uniform size, — 15-20 yu, in diameter, — are

46 BULLETIN OF THE

slightly granular, stain feebly, and exhibit each a single large (5-10 /a)
nucleus, with an even outline and a circular or oval form. When seen
in profile, — as in radial sections of the egg with its membrane and
granulosa (Plate V. Fig. 3), — a majority of the cells are observed to be
very thin, and their nuclei flattened ; but there is occasionally a cell
whose nucleus is not so much flattened, and which thei-efore protrudes
beyond the general surface of the granulosa. Radial sections of the
ovum with its granulosa are further instructive in showing the rela-
tions of the cells to the heads of the villi. Each granulosa cell cor-
responds in size to front four to eight villi, but there is no constancy in the
position of the cells or their nuclei in reference to the underlying villi.
Nothing intervenes, however, between the cells and the villi except
occasional artificial spaces. Externally the granulosa is limited by a
thin, homogeneous delicate membrane, the membrana propria (th. fol.)
of the theca folliculi.

This is the condition which obtains over all parts of the egg except
in the vicinity of the micropylar funnel. Elsewhere the granulosa re-
tains great uniformity of thickness. At a considerable distance from
the micropyle its cells begin to elongate so that the granulosa grows
thicker ; as the cells approach more and more the condition of columnar
epithelium they become inclined, their outer ends being directed to-
ward the axis of the micopyle (Plate VII. Fig. 1). They still continue
to form a layer only a single cell deep until they reach the vicinity of
the rapid declivity in the wall of the funnel. Here the cells, having
now attained an elongated columnar form, become superposed, and fill
completely the micropylar funnel. With a single exception the cells com-
posing this mass are fairly similar to each other. They are considerably
elongated, irregularly columnar or spindle-shaped, and contain each a
single oval nucleus about 10fi by 8 or 9/x in diameter. The cells
themselves vary from 15//, to 40 /a in length, and are about 10 /a in
diameter. When the hardened egg, with its membranes, is removed
from the follicle, it often happens that this conical plug of granulosa
cells is left with the rest of the granulosa in the follicle. But even
when the majority of the granulosa cells of the plug are thus removed
from the funnel, there is usually left behind a single one which is unlike
the others. It occupies the bottom of the funnel, which it completely
fills, and is much larger than any other of the granulosa cells (m py. cl.
Plate IV. Figs. 1, 4, 5, Plate V. Fig. 2', Plate VII. Fig. 2).

When I first became aware of the existence of such a cell it was from
the study of radial sections of a recently deposited egg in which a

MUSEUM OF COMPARATIVE ZOOLOGY. 47

" maturation spindle " was visible near the micropylar pole (Plate IV.
Fif. 1). As there were no other granulosa cells left attached to the
egg, the first impulse was to regard this as one of the " polar cells "
formed by the ovum during maturation. This seemed the more prob-
able on account of the undoubted existence of a maturation spindle.
A serious obstacle to this view was the great size of the cell as com-
pared with the narrow mycropylar canal. Even the elongated condition
of the cell would hardly warrant the assumption that it had passed
through so narrow an orifice. The examination of suitable sections
from ovarian ova (Plate IV. Fig. 5, Plate V. Fig. 2, Plate VII. Fig. 2)
soon showed that this interpretation was inadmissible, and made it as
certain as one could expect, without having traced it from its origin, that
the cell in question was a specially modified granulosa cell. It may be
appropriately called the micropylar cell, for, whatever may be its function,
the morphological fact remains that it occupies the micropylar funnel,
and lies directly over the micropylar canal. I have not been able to dis-
cover that its substance extends into the canal, but the number of favor-
able cases which I have examined is not enough to allow me to say that
such a condition is improbable. So far as I know, nothing of this kind
has been found in the case of any of the osseous fishes, unless the figure
given by Hoffmann ('81, Taf. I. Fig. 20) for Leuciscus is capable of
bein" thus interpreted.1 Hoffmann himself has evidently not considered
the condition of the granulosa in the region of the micropyle sufficiently
important to give it any attention in the text, but there is not the least
doubt in my mind that the accumulation of granulosa cells which he
has figured is the equivalent of the granulosa plug in Lepidosteus. I
am inclined to believe, moreover, that Hoffmann has overlooked a real
difference between the cells in this region, and that an equivalent of the
micropylar cell of Lepidosteus will be found in Leuciscus, and perhaps
in many other of the osseous fishes, especially in those where there is a
large micropylar funnel. In fact the three cells which in Hoffmann's
figure (Plate I. Fig. 20) seem to occupy the funnel, are all slightly larger
than the remaining granulosa cells, and one of them — the deepest —
fairly represents in its position the micropylar cell. Since all the cells
have a somewhat diagrammatic appearance, it is not too much to expect
that a more careful examination would show a difference between them.

1 Since this account was written, Owsjannikow and Cunningham have both
found similar conditions in other fishes. A review of their articles will be found
at the end of the historical section of the present paper, pp. 104-110.

48 BULLETIN OF THE

d. Origin of the Zona Radiata and the Villous Layer.

The youngest ovarian eggs in which either of the egg membranes has
been observed were about 430 fx in diameter, and the ovaries to which
they belonged were preserved just before the period of spawning began.
Sections of such an egg are shown in Plate VIII. Figs. 1 and 2. Tan-
gential sections (Fig. 2) show that the egg is enveloped in a layer of
polygonal granulosa cells whose boundaries are exceedingly faint, and
whose nuclei have very irregular outlines, being lobed or deeply incised,
in some cases almost to complete division. The nuclei contain one, and
frequently two small nucleoli, but otherwise appear homogeneous, and
are uniformly stained. Upon focusing just below this layer of granulosa
cells, one sees the surface of the yolk covered with innumerable fine,
close-set points, which are evenly distributed.1

Radial sections (Plate VIII. Fig. 1) supplement the surface views, and
show that the granulosa cells are relatively thin, and easily separable
from the underlying structures. Their protoplasm is finely granular,
and their boundaries are not distinguishable ; neither do their deep
surfaces appear to be defined by any membrane. Their nuclei are
considerably flattened, and irregular in outline.

Immediately beneath the granulosa the surface of the yolk exhibits
fine radial, nearly parallel markings, which are close together and very
short. They are so intimately joined to the yolk that they seem to form
an integral part of it, and nowhere show the least tendency to become
detached from it. With high powers one can recognize a very thin corti-
cal portion of the yolk (membrane ?), with which they seem to be contin-
uous. It is very difficult to ascertain the distance between the markings,
but about 21 of them may be counted in the space of 17 fi, so that the
average distance is not far from 0.8 //,. The length of each is about 0.5 /*,.

It would not be easy to determine from this stage alone whether the
markings indicate the beginnings of the formation of the zona radiata or
the villous layer. But even in this early condition the punctate mark-
ings of tangential sections appear brighter rather than darker when one
focuses high, so that the inference must be that they are due to minute
bodies which are more highly refractive than the surrounding substance.

This conclusion is abundantly confirmed by the study of somewhat
larger ova. These bodies seem to increase in length with considerable

1 In Fig. 2 (Plate VIII.) these punctations appear much too scattered in the
middle of the area which shows them. They are better represented toward the
margin of the area.

MUSEUM OF COMPARATIVE ZOOLOGY. 49

rapidity, for when the egg has attained a diameter of about 600 ll
(Plate VIII. Fig. 3, Plate IX. Figs. 4, 5) they may have reached the
length of 3-3.5 [x. In this stage the layer when seen from the surface
presents an appearance (lower half of Fig. 3, Plate VIII.) which so
closely resembles that of the zona radiata in the mature egg, that oue is
involuntarily led to believe that it is the zona. Even the peculiar ar-
rangement of the markings in curved lines recalls the appearance of the
zona when seen in a similar position. Notwithstanding the striking
resemblance, there cannot be the slightest doubt that this layer is not
the zona radiata. In radial sections it is difficult to distinguish between
a layer composed of a homogeneous matrix pierced with minute parallel
canals, and one composed of parallel rod-like structures, but in surface
views this is much easier. Careful focusing shows the same optical
properties as were observed in the earlier stage, and with much greater
distinctness. The staining, too, is such as' is to be observed in the villous
layer rather than in the zona ; for the highly refractive bodies take the
deeper stain, the intervening substance having the paler color of the yolk.
But the last possibility of doubt concerning the nature of this layer is dis-
pelled by the appearance presented when the elements which compose it
are separated from each other. It frequently happens in mounting thin
sections that portions of the layer are detached, and even resolved into
their constituent elements. In such cases clusters of two or three rod-
like bodies, aud even single ones, can be found in such proximity to the
layer as to leave no doubt that they are elements detached from it.
They have the same length and thickness as the markings of the layer;
they are highly refractive and deeply stained. They can in no way
correspond to anything that is observed in the zona radiata. but do
resemble in several particulars the villi of older eggs.

From all this evidence I am certain that the layer which is first to
make its appearance between the yolk and the follicular epithelium i" *hc
villous layer.

In this stage, too, the union of the layer with the yolk is much more
intimate than its relation to the granulosa. The latter is often sepa-
rated from the layer, the yolk never.

The cells of the follicular epithelium (Plate VIII. Fig. 3) have be-
come somewhat smaller than in the previous stage, but their nuclei
retain the same dimensions and the same lobed appearance which they
had during the earlier stage. As a consequence, the nuclei are closer
together. It will be seen that in the stage figured on Plate VIII.
Fig. 3, the diameter of a single average-sized granulosa cell corresponds

VOL. xix. — no. 1. 4

50 BULLETIN OF THE

to the distance occupied by about a dozen of the villi. This tact -will be
of some interest later, when a comparison is made with the conditions in
the mature egg.

In the sections figured on Plate IX. the villous layer has become still
thicker and the villi are correspondingly elongated ; they are also some-
what farther apart, as well as thicker.1 The thickness of the individual
villi is really greater than that of the spaces intervening between them,
but the appearance as seen under the microscope is represented with
tolerable accuracy in the figures. The villi' of the egg shown in Fig. 3
(Plate IX.) have attained a little greater length than those of the other
eggs figured, but the egg itself was probably somewhat smaller than the
one shown in Plate IX. Figs. 1 and 5. I am not entirely certain of this,
because the egg was incomplete, the yolk having all disappeared except
a portion directly underneath the villous layer.

A more advanced condition in the development of the ovum and its
membranes is to be seen in Plate VII. Fig. 5. The evidence that this
egg is more advanced than those last described is found in its slightly
greater size (nearly 0.7 mm.), and also in the increased size and elon-
gated condition of the yolk bodies which already occupy all parts of the
egg except a peripheral layer. The villous layer has here attained a
thickness of 5.5 /*, or about one third its thickness in the mature egg,
but the individual villi have not changed perceptibly from the condition
in the previous stage, except in regard to length.

I have no stages between this condition and that which the eggs pre-
sent at maturity, but already enough of the egg membranes has been
formed to allow several conclusions as to the method of their produc-
tion.

It is to be observed, that immediately before spawning there is no
structure, even in the latest of the stages here described, which can be
considered the zona radiata ; neither are there at this time any stages
older than the one last described, except the mature ova. It seems to
me, therefore, perfectly safe to infer that the zona radiata is developed
after a large part, if not the whole, of the villous layer has been produced,
and that it is wholly formed during the twelve months immediately preced-
ing the spawning. From its late production and its position inside the
villous layer, as well as its intimate relations to the yolk, it is further to

1 In Fig. 5 (Plate IX.) they are represented a little too far apart and not quite
thick enough, whereas in Fig. 3 (Plate IX.) they have been represented too close
together. The granulosa cells in Fig. 6 are too sharply defined, especially on the
side toward the villous layer.

MUSEUM OF COMPARATIVE ZOOLOGY. 51

be inferred that the zona radiata is exclusively the product of the yolk. It
is also probable, from the evidence of stratification sometimes seen in
the completed structure, that the zona is produced in successive layers.
If such is the case, it follows that portions of the zona nearer the yolk
are formed after those which have a more peripheral position.

The question as to the source of the villous layer is not so easily an-
swered. The fundamental difference between it and the zona radiata at
once suggests for it a different origin. If the latter arises from the yolk,
the former might be produced by the follicular epithelium. This view
would seem to receive confirmation from the peculiar way in which the
roots of the villi in the mature egg penetrate the pore-canals of the zona
radiata. I have no doubt that this condition would be regarded by
many observers as a welcome confirmation of the theory that the pore-
canals are primarily for the purpose of transmitting nutritive material
to the growing egg. Such observers might look upon the villi as secre-
tions from the granulosa, which, owing to slight physical and chemical
changes, had not passed through the pore-canals as nutriment, but re-
mained partly outside the zona to subserve other functions. This view
might be further supported by the fact that during the formation of the
villi the inner surfaces of the granulosa cells are not sharply marked off
by membranes from the underlying structures.

Nevertheless, it seems to me that the arguments which may be
adduced to support the opposite view, — that the villous layer is the
product of the secretive activity of the ovum itself, — greatly outweigh
these considerations.

During the early stages of their formation the villi are so intimately
related to the ovum that they appear to be rods imbedded in its sub-
stance, and at no time during its formation is the villous layer separable
from the yolk. If the latter is by any means removed from the mem-
brane, there is always a superficial portion of the ovum which remains
attached to its inner surface. The separation of the granulosa cells
from the membrane during this period, on the contrary, is quite com-
mon. What might otherwise be a 'serious obstacle to considering the
villi the product of the ovum, — the presence of a zona between the
two, — is entirely nullified by the fact, previously established, that the
villous layer is produced before the zona radiata.

Whatever renders improbable the formation of the villi from the fol-
licular epithelium is, of course, favorable to the opposite view. If the
villi were products of the epithelium, one would expect some constancy
in the numerical relations between the two, but this is certainly wanting.

52 BULLETIN OF THE

I have made some measurements and comparisons between eggs half
a millimeter in diameter and those having a diameter of about two milli-
meters, which indicate that the number of the villi remains constant
during the period of growth from the smaller to the larger size.

In an egg 0.5 "mm. in diameter there occur about 30 villi in a space
of 35 /a ; i. e. the villi are about 1.15 /a from centre to centre. In an
egg 2 mm. in diameter from the same ovary, treated in the same manner
and cut at the same time, the villi are 4.5 /x from centre to centre (com-
pare Plate V. Figs. 3, 4). Allowing for the growth of the smaller egg,
which at the larger size would have a diameter four times as great as at
first, it is evident that the interval for a villus would be four times 1.15 fi,
or 4.G (A, which agrees fairly well with the space (4.5 /x) actually occupied
by a villus in the larger egg measured. There are also other reasons
for believing that the villi do not increase in number after the egg has
reached a diameter of half a millimeter. If new villi were interpolated,
one would reasonably expect to find the younger ones shorter than the
older ones; but at no stage which I have seen is there any marked
difference in their lengths.1

In the larger eggs measured (2 mm.), the nuclei of the granulosa were
on the average about 14 /a apart, from centre to centre; i. e. there were
about three villi to the diameter of each cell. But in eggs about half a
millimeter in diameter (compare Plate VIII. Fig. 3, and Plate IX. Fig. 5)
it is to be seen that from six to fourteen villi correspond to the diameter
of a single granulosa cell. If there has been no change in the num-
ber of villi, it follows that the granulosa cells must have increased in
number at least fourfold between the half-millimfcter stage and the two-
millimeter stage. It is for this reason I contend that there is no con-
stancy in the numerical relations of villi and granulosa cells, and that
consequently it is improbable that the former are the product of the
latter.

1 It is evident that there has been a corresponding increase in the diameter of the
individual villi during the growth of the ovum, for in the mature condition they
form a continuous layer, with little or no intervening substance.

Eansom ('67) has claimed that the pore-canals of the zona radiata increase in
number during the growth of that membrane. If one were to disagree with me,
and to regard the markings which first appear at the surface of the ovum as the
incipient zona instead of the villous layer, he would be compelled to adopt Ransom's
view, for the intervals between the markings on eggs half a millimeter in diameter
(1.15 ju,) would become, unless there were interpolations, 4.6 fj. apart when the eggs
had increased to two millimeters in diameter. In order to reduce the intervals to
the condition actually found in the zona of the mature egg (1.4 n), the number of
pore-canals would have to be increased more than threefold !

MUSEUM OF COMPARATIVE ZOOLOGY. 53

At first thought one might regard the modifications of the villous layer
in the micropylar region as the direct result of an alteration in the secre-
tive powers of the granulosa cells situated at that place ; but it seems
to me that the thickness of the layer ought, on this assumption, to be
greater than elsewhere, since the granulosa cells are here more numerous
and larger. Besides, the corresponding diminution in the thickness of
zona radiata could not be thus accounted for, but must be assumed to
be the result of diminished secreting activity on the part of the ovum in
this region. Hence the same explanation would certainly be more rea-
sonable in the case of the villous layer. This is a point which seems to
me of considerable importance; the diminished activity of this region
which is shown during the formation of the zona was already manifest
during the formation of the villi.1

From these several considerations, I believe there can be little ques-
tion that the villous layer of the egg membranes in Lepidosteus is also
the 2^oduct of the ovum itself rather than of the follicular epithelium
surrounding it.

If this conclusion is established, it follows that the parts of the villi
first to be produced are those which are most superficial. I believe that
this is confirmed by the fact that the forming villi are readily stained in
carmine. It is probable that, even in the latest stage of the immature
eggs (0.7 nun.) which I have seen, not much, if anything, more than the
heads of the villi have been produced. The length and the highly re-
fractive condition of the villi at this stage, and the fact that they are
not at all folded, all point to this conclusion.

There still remains much to be done in following out the exact course
of the development of the membranes in Lepidosteus, — especially in
determining when the formation of the zona begins in relation to the
completion of the villous layer, — but I think that the main features of
the process as outlined above will not be disproved by subsequent
study.

I have no explanation to offer of the apparently sudden change in the
nature of the secretions from the ovum which is registered in the pro-
duction of structures so dissimilar as the zona and villous layer are ;
but it is possible that some light may be thrown on this question when
the period of the transition has been carefully worked out.

1 This is an evidence of the polar differentiation of ova (which exhibits itself in
many other phenomena) to which attention has not hitherto been called.

54 BULLETIN OF THE

B. Historical and Critical Review of the Literature on the
Primary Egg Membranes1 and the Micropyle in Fishes.2

It is possible that the eggs of fishes may present as many as four
essentially distinct kinds of enveloping membranes before separation
from the ovary. The innermost of these, if it exists, may be considered
a true vitelline membrane, the equivalent of the cell membrane in general.
I have made no observations concerning it, and shall have little to say
regarding the conflicting testimony as to its existence. The second, pro-
ceeding from the yolk outward, is radially striate, and I shall call it, as
in the preceding description, zona radiata. Although this is totally dif-
ferent in structure from the next membrane, there are several reasons
why it will be best to consider both at the same time. This third
membrane I shall call, as previously, the villous layer. The fourth and
outermost, when it exists, is formed exclusively from the granulosa cells,
and may be called by the name first given to it by Johannes Miiller, —
capsular membrane}

a. Cyclostomata.

The eggs of the myxinoids are enveloped in a " horny capsule," which
was first described by Thomson ('59, pp. 50, 51) for Myxine glutinosa.
He evidently considered it the equivalent of the egg cases of selachians.
Since the latter are formed in the oviduct, they cannot be considered

1 I use the expression primary egg membranes in the sense in which it has been
employed by Ludwig ('74 p. 197), i. e. for all membranes which are the product of
either the ovum itself or the follicular epithelium surrounding it.

2 Owing to delays in publishing my studies I have been able to extend this
review, and to bring it down so as to include papers which have appeared since
my own account was written.

3 I have the less hesitancy in adopting this name because Miiller ('54, p. 189) —
notwithstanding some misconceptions as to its real nature in the perch — gave the
following concise, and, in my opinion, still perfectly applicable definition: "Eine
von dem Eifollikel, Ovisac eines Wirbelthiers erzeugte Eihiille scheint von der
Eischale anderer Eier unterschieden werden zu mussen als capsulare Eihiille, oder
Eicapsel." When subsequent observers, — as for example His ('73), — ignoring the
true explanation of Midler's investigations given by Leuckart ('55, pp. 257-260),
transfer the name Eicapsel to the zona radiata, one is compelled to protest that
that was not the structure described by Miiller under the name of "Eicapsel," and
that no one has yet brought forward satisfactory evidence that the zona is "pro-
duced by the egg follicle," as Midler's definition demands. It therefore seems to
me that it is better, for the sake of avoiding confusion, to drop entirely the name
capsule — whether egg capsule or "cartilage capsule" (His) — as a designation
for the zona radiata.

MUSEUM OF COMPARATIVE ZOOLOGY. 55

as primary egg- membranes; but Steeustrup ('63) subsequently showed
that the egg of Myxine glutinosa possesses this covering before it leaves
the ovary, from which it follows that the " horny capsule " is really a
primary membrane.

Thomson's ('59) account is brief: "I have found that in the Myxine
glutinosa the globular yolk is enclosed in a horny capsule of similar
consistence and structure [to that of the oviparous cartilaginous fishes],
but of a simple elongated ellipsoidal shape, and in place of four terminal
angular tubes, a number of trumpet-shaped tubular processes projecting
from the middle of the two ends, which probably serve the same pur-
poses as the differently shaped appendages of the ova of the shark and
skate."

Steenstrup ('63, pp. 233-238, Figs, a-h) also saw the horny egg-
shell and the peculiar projections from its ends. He says (p. 236) :
" In the last received individuals the eggs now had not only the same
considerable size [as some large eggs previously described] and more
oval-elliptical form, but besides they were surrounded with a somewhat
firmer, almost horn-like egg-shell, which was furnished at the ends with
a large number of slightly curved or S-shaped horn -threads. Each
horn-thread ends in a head-shaped portion with three or four projecting
spines or hooks, and has thereby some resemblance to a ship's anchor.
The threads recall — even though somewhat remotely — the horn-threads
projecting from the eggs of the rays and sharks, much as the shell itself
recalls the firm capsule of these cartilaginous fishes. The accompanying
figures exhibit both the appearance of the capsules (/, g) and the man-
ner in which they hang in the mesovarium (A** and A***), together
with eggs of the same appearance as c, d, e (Fig. A*), and with a large
number of only slightly developed eggs (o, o, in Fig. A)."

In the two eggs with horny shell figured by Steenstrup, the shell has
been represented as though it were composed of two parts separated by
a sharp continuous line ; the egg appears cut through near one pole by
a plane perpendicular to its long axis. The appearance recalls that seen
in the egg-shells of certain trematodes, where one end serves as a lid
which opens to allow the larva to escape ; but whether the author re-
garded this as a similar provision for the escape of the young hag, or as
an accidental condition, is not stated in the text.

Wilhelm Muller (75, pp. 114-117, Taf. V. Figs. 14, 15) appears to
regard the "Testa" of Myxine glutinosa — which I suppose to be the
same as the "horny capsule " of Allen Thomson — as resulting from the
secretions [metamorphosis 1] of a layer of [granulosa] cells, which imme-

56 BULLETIN OF THE

diately invest the ovum. He does not expressly state this, but it seems
to me he leaves one to draw such an inference. He says that the
ovarian egg when 0.6 mm. in diameter is surrounded by a single layer
of very fiat polygonal cells, outside of which is a thick layer of fibrous
connective tissue, and that when the eggs have attained a length of
18 mm. and a thickness of 6 mm. there are two connective-tissue
envelopes; an outer thinner, a continuation of the mesovarium, and
an inner, which at the ends of the egg is thickened (0.4 mm.) and
vascular. At its inner surface the inner membrane is condensed into
a lustrous membrana propria 2 p thick, and is firmly attached to the
underlying " Testa." In contact with the inner surface of this mem-
brana propria is a layer of cells. In the middle of the egg the cells are
cubical, but they become more and more cylindrical towards its poles,
where the layer becomes three or four cells deep.

I believe there can be no question that this layer of cells inside the
membrana propria represents the granulosa ; but it seems as though
Miiller must have overlooked the egg membrane, if one existed at that
stage, and must have taken the granulosa to be in some way the equiva-
lent of it. Perhaps, assuming that the granulosa cells secreted the
membrane, his idea was that the granulosa ought itself to be considered
as a part of the "Testa," for he afterwards (p. 126) mentioned, in the
case of Petromyzon Planeri, "a very thin folded egg membrane which
exhibited a polygonal pattern when seen from the surface." Moreover,
he says, with regard to two deposited eggs of Myxine which he examined,
that there was no trace of either inner or outer connective-tissue en-
velope, and from this fact concludes that they must have undergone
complete regressive metamorphosis, similar to that which the enamel
organ of the teeth suffers after the completion of the enamel.

W. Miiller is the only person who has seen anything of a micropylar
apparatus in the myxinoids. " Exactly in the middle of the white pole
of the egg," he says (p. 115), "this cell layer [granulosa] exhibits a
conical infolding 0.1 mm. deep and 0.06 mm. broad, which contains a
funnel-shaped opening, the micropyle, which is directed straight toward
the underlying nucleus and the protoplasm surrounding it." This is
the whole of his description ; and from it I infer that he has seen that
portion of the granulosa which occupies the micropylar funnel, but that
the micropylar canal — which is a passage through a membrane, not an
involution of a cell layer — has not been seen by him. If the condition
in Myxine is at all comparable with that in Lepidosteus, it is certain

MUSEUM OF COMPAKATIVE ZOOLOGY. 57

that Miiller has seen the equivalent of what I have called the micro
pylar plug ox granulosa cells, and it is therefore probable that he was
the first person to observe that peculiar structure in any fish-like animal.
If he were less positive in his assertion that the infolding contained an
opening, I should question if the cells took the form of a hoDow funnel ;
even as it is, I doubt if the membrana propria is infolded.1

The first account of the membranes in Petromyzon Planeri was by
Max Schultze ('5G, pp. 1-5). When taken from the body, the eggs had
besides the yolk membrane a firm " Eischalenhaut," or "chorion," which
was surrounded with a scarcely discernible thin layer of gelatinous sub-
stance, which was quickly swollen, when it came in contact with water,
to a thickness of not more than a quarter of a line. It was delicate and
fugitive, and was easily removable from the firm underlying membrane.
In the course of eight days it mostly disappeared, being dissolved in the
water ; it was not an " albuminous layer," but was rather to De compared
to the gelatinous mass uniting frogs' eggs ; its chemical composition was
not known.

The firm " Eischalenhaut," which closely enveloped the egg, was a
clear membrane about 0.0015'" (probably should be 0.015'", or about
0.03 mm.) thick, which had a tendency after being torn to roll in at
the edges. It appeared very finely punctate when viewed from either
the inner or the outer surface. Schultze was inclined to regard the
punctations as due to very fine canals traversing the membrane, but
on account of the delicacy of the object he could not reach a perfectly
satisfactory conclusion on this point. For this, finely punctate mem-
brane and that found in bony fishes, the author would use the name
chorion rather than vitelline membrane, for a true vitelline membrane
(or egg-cell membrane) exists inside the punctate structure.

Owsjannikow ('70a, p. 184) says that the gelatinous layer of the outer
egg membrane is very little developed, so that the fertilized eggs are
only feebly attached to the objects on which they fall, the least current
carrying them away.

Calberla's ('78, pp. 438-441) account is in some particulars more
extended than that of Schultze. The eggs, he says, instead of being
round, are slightly ellipsoidal. The membrane (zona) consists of two
layers, which are not, however, sharply separated from each other. The
outer is highly refractive, rough externally owing to all sorts of eleva-
tions and tooth-like structures (Zacken) ; the inner is much thinner

1 For a review of more recent work on Myxine, see pp. 91-93, 107-110.

58 BULLETIN OF THE

and translucent. With low powers the outer appears as though made
up of concentric layers, but with higher powers it is seen to be a
homogeneous substance traversed by fine radial canals which are con-
tinuous with those passing through the inner layer. At the outer sur-
face each of these canals opens out at the base of one of the elevations
(Zacken). Calberla regards this whole layer as a secretion from the
peripheral layer of the yolk. The proof of it he finds in the conditions
of the membranes in nearly ripe and in over ripe eggs. On the former,
the boundary between the two layers is sharper and the inner layer is
much thicker than on mature eggs ; whereas on the latter all distinction
between inner and outer layer has disappeared.

As soon as the egg comes in contact with the water, the tooth-like pro-
jections on the surface of the egg membrane (zona) quickly swell, in con-
sequence of which the whole egg appears as if surrounded with a delicate
area of hyaline substance. This may well be the cause, he adds, of the
stickiness of the surface of the egg.

It seems to me that there is considerable reason for believing that
these external projections described by Calberla correspond to the villi
of Lepidosteus, both in function and in position. An examination of his
figures (Taf. XXVII.) lends support to this view. I believe also that,
when the genesis of the membrane has been studied, it will be found
that these "Zacken " are formed before the zona itself. It is true that

Kupffer und Benecke ('78, pp. 9, 10) find the conditions somewhat
different from those recorded by Calberla. They claim that the envelope
of the egg consists in both P. Planeri and P. fluviatilis of a double mem-
brane (Eihaut), and of a continuous covering of gelatinous material which
is replaced at the watch-glass-like elevation of the membrane by a struc-
ture known as A. Muller's "Flocke." The inner membrane — which
they figure as being much thicker than the outer — contains closely 6et
pore-canals, but these they assert positively are not continued into the
outer layer. The difference in structure between the two membranes is
demonstrable by means of 0.5 per cent hydrochloric acid. The outer
membrane swells more, in water than the inner, but not quite uniformly.
It appears here and there as though it were restrained by a filament of
less easily-swelling substance. And this, they say, is probably the cause
of " Calberla's unzutreffende Angabe, dass diese Rindenschicht mit
allerlei Erhebungen und Zacken besetzt sei, an deren Basis Poren-
canale miindeten."

But even if Calberla's description is not quite satisfactory, it is evident
that this outer envelope is not homogeneous, and that the toothed appear-

MUSEUM OF COMPARATIVE ZOOLOGY. 59

ance which he has figured must have had a basis iu optically different
portions of that envelope. According as the imbibition of water has
proceeded less or more, this marking might be more or less conspicuous.
From a comparison of the figures by Calberla with those by the last
mentioned authors, I should think that Calberla's outer layer of the
zona by no means corresponded with the outer layer of Kupffer und
Benecke, and that the latter, being very thin, had been overlooked by
Calberla.

The micropyle of Petromyzon, though sought for by Schultze ('56)
and A. Miiller ('64) was not found by them.

Owsjannikow ('70a, p. 184), who discovered it, says that it is very
small, but that it remains visible for several days after fertilization. In
mature eggs it occupies a position over the eccentric nucleus.

Calberla ('78, pp. 439, 440) has given a careful description of the
micropyle, which, he says, agrees in all essential particulars with that of
osseous fishes. His account is substantially as follows. At one pole
of the elongated egg its membrane is thickened, and bulges out, much
as though a shallow watch-glass — with shorter radius of curvature than
the rest of the egg membrane — had been set into one end of the mem-
brane. Radial sections which pass through the centre of the elevated
portion of the membrane show that in the middle of it there is a very
flat saucer-shaped depression, the centre of which is further depressed
into a funnel. From the narrow end of the funnel a canal is continued
through the membrane, and opens on its inner surface with a slight
flaring. A little below its middle the canal exhibits a spindle-shaped
enlargement, which is shown in Calberla's Taf. XXVII. Figs. 2 and 3.

The views held by Kupffer und Benecke ('78, pp. 9-15) regarding
the nature of the micropyle are not easily summarized. They are based
on close observations of the deportment of the egg and spermatozoa at
the time of fertilization, but do not appear to have been corroborated
by sections of the egg membranes.

In the region of the watch-glass segment of the membrane described
by Calberla, the mucilaginous envelope outside the membranes is want-
ing, and in its place is a hyaline dome (A. Midler's " Flocke ") composed
of a substance which, unlike the mucilaginous layer, is permeable for
spermatozoa. Usually only one spermatozoon passes through the inner
and outer egg membranes and reaches the yolk ; but the place of its
passage is by no means always the centre of the watch-glass area. It
was such only six times out of fifty. The passage may occur even near

60 BULLETIN OF THE

the margin of this area. Neither is it always the spermatozoon that
first reaches the outer membrane, after having traversed the " Flocke,"
which passes through.

The statement that the egg membrane is not alone permeable at a
single spot would lead one to suppose that the authors were ready to
deny the existence of a micropyle. They do not, however, directly assert
its absence, although they were unable to find anything of it on the un-
fertilized egg. But as soon as the spermatozoon has passed through the
membrane, a small circular spot may be seen from the surface ; this is
due to a shallow depression in the surface of the inner layer of the mem-
brane, the outer layer never showing any passage through it. The authors
hint at the possibility of a chemical action on the part of the spermato-
zoon resulting in a loosening of the two layers and a partial solution of
them, and endeavor to make that view harmonize with the conclusion
that the micropyle " is the remnant of an opening in the inner layer of
the egg membrane, which exists during the stay of the egg in the fol-
licle, corresponding to the condition which Herr von Jhering recently
established in the case of the eggs of the mussels." The outer layer
would be formed, they imagine, afterwards, and would cover over this
opening, leaving a remnant of it recognizable on the inner membrane.

" The micropyle, therefore, is not an open passage, as it appeared from
Calberla's description and drawings, but only a permeable place."

b. Selachii.

What Ludwig wrote in 1874 concerning oogenesis in the selachians,
that it had been studied by only a very few investigators, was equally
true of the primary egg membranes of the group. Ludwig ('74, p. 145)
himself, although he studied the development of the ova, had nothing to
add to what was already known about the egg membranes, and since him
there have been only two writers who have dealt with the subject,
Schultz and Balfour.

Leydig ('52, pp. 87, 88) speaks incidentally of a vitelline membrane, and
a thin albuminous layer surrounding it, in the case of Rajabatis. The latter
probably corresponds to one of the membranes seen by later observers.

Gegenbaur ('61, p. 518) recognized the existence of a homogeneous
egg membrane on eggs of Raja from 1"' to 2'" (2-4 mm.) in diameter ; its
external contour was delicate, but internally it was sharply limited. In
the case of Acanthias there was only this one membrane to be observed;
it attained a thickness of 0.08'" (175 /x) on eggs 4"/-5'" (9-11 mm.) in
diameter.

MUSEUM OF COMPARATIVE ZOOLOGY. 61

Gegenbaur considers it probable that this membrane is produced by
the follicular epithelium, but is evidently not certain of it. He says :
"Es liegen hier wohl bei den Selachiern andere Verhaltnisse vor als bei
den Vogeln und Reptilien, und eine Dotterhaut, wie sie dort von Seite
des Dotters durch Umwandlung seiner peripherischen Schichte zu Stande
kam, kommt hier wohl nicht vor, sondern der Dotter bleibt auf dem
friiheren Stadium der Differenzirung bestehen, dagegen bildet sich eine
Hiille von aussen her, wozu wabrscheinlich die Zellen des Follikelepithels
das Material abscheiden, wenn man den Vorgang der Bildung jener
Membran nicht auf die Oberfliiche des Dotters selbst verlegen will."

Schultz and Balfour disagree in their conclusions as to the origin of
the fugitive rrembranes which envelop the ovarian eggs of selachians.
Schultz ascribes their formation to the follicular cells ; Balfour, to the
ovum itself.

Schultz ('75, pp. 574-576) claims that in Torpedo oculata the fol-
licular epithelium is composed of two kinds of cells : genuine granulosa
cells, derived from the germinal epithelium of the ovary, and, alternating
with them, lymphoid cells, which are derived from the stroma of the
sexual organ. " The cells of this follicular epithelium, especially the
lymphoid cells, are merged at their deeper ends into a homogeneous
cuticular layer (Fig. 8), and there form a structure having the morpho-
logical value of a chorion." This homogeneous layer at no time has a
morphological relation to the egg protoplasm, but retains the closest con-
nection with the follicular cells. On objects subjected to pressure the
outer margin of the homogeneous layer appears jagged like a wood-saw,1
the remnants of the lymphoid cells corresponding to the teeth, in the
intervals between which the granulosa cells are lodged. The latter are
also attached, he says, to the homogeneous layer by means of proto-
plasmic processes, and even appear to fuse with it, but do not show any
differentiation within the substance of the layer. It is not possible
even with the highest powers to demonstrate any such structural pecu-
liarities (radial striation, pore-like perforations) as are met with in the
egg membranes of most classes of animals, even in Raja batis itself.

" Finally, when the egg cell has reached maturity and the follicle
approaches the stage of rupturing, the lymphoid cells together with the
homogeneous layer are converted into connective issue, in the inter-
stices of which the granulosa cells persist, although the latter finally
undergo fatty degeneration. Only at a single place, corresponding to
the whole extent of the germinal disk, do the follicular cells and the

1 " Gleichsam hohlsageformig [hohlzsageformig ?] gezackt."

62 BULLETIN OF THE

homogeneous la}rer persist unchanged up to the I arsting of the follicle.
It is from this part that those granulosa cells come which are occasion-
ally encountered on the escaped [egg] and within the empty follicle."

On eggs of Acanthias, Scymnus, and Mustelus, Schultz found «i
homogeneous layer joined with the follicular layer, and inside the latter
a zona radiata, the inner margin of which was sharply defined against
the yolk. " The pores of this cuticular zona were traversed by proto-
plasmic processes, which stretched from the homogeneous layer to the
egg protoplasm and fused with the latter."

The author concludes that, so far as his own observations reach, there
are to be distinguished in selachians the four "following conditions
of the follicular epithelium " : (a) simple epithelium (embryonic stage
of selachians) ; (6) epithelium with homogeneous basal margin (Tor-
pedo); (c) epithelium with homogeneous perforate basal margin (Raja) ;
(</) epithelium with broad homogeneous and narrower perforate basal
margin (Squalida)).

Balfour ('78b, pp. 402, 403) has confirmed the existence and subse-
quent disappearance of two membranes — an outer homogeneous, and
an inner striate — in one of the Squalida?, Scyllium ; but he believes
that they are produced by the ovum, not by the follicular epithelium,
and that they are absorbed, not converted into connective tissue. Two
similar membranes are also found in Raja, and are believed by Balfour
to be common probably to all sharks. The homogeneous membrane is
formed before the striate one. In Scyllium " the [homogeneous] mem-
brane would seem indeed to be formed in some instances even before the
ovum has a definite investment of follicular cells." Consequently it is
called a vitelline membrane. In ova 0.12 mm. in diameter it is not thick
enough to be accurately measured ; in those of 0.5 mm. diameter it has
a thickness of 2 //., and there may also be observed inside it faint indi-
cations of the differentiation of the outermost layer of the vitellus into
the perforate or radially striate membrane of Schultz. The latter Bal-
four does not hesitate to call a zona radiata.

In ova 1 mm. in diameter the zona has increased in thickness (to 4 /x)
and " is always very sharply separated from the vitelline membrane, but
appears to be more or less continuous on its inner border with the body
of the ovum, at the expense of which it no doubt grows in thickness."
In larger eggs both membranes increase in thickness, especially the zona,
which now becomes marked off from the yolk. " In many specimens it
appears to be formed of a number of small columns as described by
Gegenbaur [for the alligator] and others."

MUSEUM OF COMPARATIVE ZOOLOGY. 63

The size of the ova at the time of the maximum development of the
membranes is not stated ; but after this stage is reached both mem-
branes gradually atrophy. " The zona is first to disappear, and the
vitelline membrane next becomes gradually thinner. Finally, when the
egg is nearly ripe, the follicular epithelium is separated from the yolk
by an immeasurably thin membrane, — the remnant of the vitelline
membrane," which is no longer visible when the egg becomes detached
from the ovary. Both vitelline membrane and zona are found in Raja,
but in a much less developed condition than in Scyllium, and the zona
is developed at a much later period than in that species.

If the account given by Balfour is correct, — and his description
seems to be both more complete and more accurate than that of
Schultz, — then there is an interesting parallelism between the pri-
mary egg membranes in selachians and those of Lepidosteus and the
bony fishes. Not that the villous layer in Lepidosteus is structurally
comparable with that which Balfour calls in sharks a vitelline mem-
brane, but genetically they are alike. They are the membranes ivhich are
first to be produced, — i. e. before the zona radiata, — and they are in
both instances the product of the ovum, not of the follicular epithelium. I
shall take occasion later to refer to the theoretical importance of this
discovery by Balfour.

The ultimate disappearance of both membranes renders the formation
of a micropyle superfluous. It would be interesting to learn, however,
whether there is at any time a trace of such a structure.

c. Ganoidei.

The only ganoids besides Lepidosteus whose egg membranes have
been described are Amia and Acipenser. I have elsewhere (p. 27)
quoted Ryder's account of the membranes in the case of Amia.

From the accounts given by Kblliker, by Kowalevsky, Owsjannikow
und Wagner, and by Salensky, I believe there must be considerable
similarity between the conditions of the egg membranes in Acipenser
and Lepidosteus.

Kolliker ('57, p. 197) says that the porous membranes in the case
of the sturgeon form " three layers ; two inner, darker, thinner, closely
porous, and an outer pale, thicker layer, apparently with fewer pores.
This outer layer, which is also softer than the others, shows its outer
surface divided into small polygonal areas, which appear to correspond
to the epithelial cells of the egg capsule [follicle]. These cells are ex-
tremely delicate and pale, but yet seen from the surface they show a

64 BULLETIN OF THE

fine punctation. It as the appearance, therefore, as though these cells
secreted the porous layers ; however, concerning this, as well as concern-
ing the corresponding parts of the eggs of other animals, only careful
studies made on eggs of all ages can give an answer, wherefore I abstain
for the present from any opinion."

According to Kowalevsky, Owsjanmikow und Wagner ('70a, p. 172),
the outer membrane in Acipenser is thick, shagreen-like, and possesses
numerous very fine canals. When the ripe eggs fall from the oviduct,
this membrane sticks to objects ; with a certain amount of skill it may
be rather easily detached from the egg. The inner membrane is much
finer [has finer canals'!], transparent, and very firm.

Salensky ('81, pp. 234-236) applies the name chorion to the outer of
the two layers composing the "thick capsule" which envelopes the ripe
egg of Acipenser; the inner he calls vitelline membrane. At first the
two are so intimately joined to each other that it is difficult to separate
them ; but after the egg has been deposited for some time, the chorion
is easily detached from the vitelline membrane, and may be removed
from the whole egg. From the study of sections of stained eggs the
author determined that the stickiness and the roughness of the surface
were due, not to the chorion, but to two special cell layers which in-
vest it.

" As to the origin of these two membranes, there is no doubt that they
are derived from the two layers of cells which constitute the epithelial
wall of the ovarian follicle."

"The chorion," he adds, "is probably a product of the secretion of
the membrana granulosa of the follicle ; when the latter ruptures, the
epithelial cells remain adherent to the chorion and are expelled with
the egg, and are again met with slightly modified at the surface of the
deposited egg."

" The examination of microscopic sections of the egg shows that this
envelope, which, as has been said, is divided into two after deposit, —
into chorion and vitelline membrane, — presents three distinct layers.
The external and the internal have about the same thickness; the mid-
dle one is thinner. In separating the chorion from the vitelline mem-
brane one may convince himself of the fact that the chorion is composed
of two layers, the vitelline membrane of only one."

From Mayzel's abstract (Salensky, 79, p. 220) I learn further, that
the outer layer is stained deeply by hematoxylin, the two remaining
layers not at all, and also that all three layers are radially and finely
striate. In the figure of the membranes given by Salensky ('78b,

MUSEUM OF COMPARATIVE ZOOLOGY. 65

Tab. I. Fig. 8 E) the inner membrane is only slightly thicker than the
middle one, and both present a lighter appearance than the outer
one.

I believe it is probable that the outer layer will be found to corre-
spond closely to the villous layer of the gar-pike. There can be no
doubt that the inner layer is the zona radiata, and I am inclined to
regard the middle layer simply as the differentiated outer half of the
zona ; but the question can be answered satisfactorily only after renewed
investigations which give more particular attention to this point. The
principal reasons for my conclusion regarding the middle layer are, that
it evidently resembles the middle layer more than the outer, especially
in its capability of being stained, and that differences between the inner
and outer portions of the zona have been observed in the case of other
fishes. I know of no case, I admit, in which the outer half of the zona
may be easity removed with the villous layer, so that it still is possible
that the middle layer in Acipenser corresponds to the stalk region of the
villi in Lepidosteus.

I do not clearly understand what the author means by saying that
the two membranes are derived from the two layers of cells which con-
stitute the epithelial wall of the follicle. It is true he claims that there
are two distinct cell layers, which, according to his figures of early
stages- ('78b, Tab. I. Figs. 5-7), are "granulosa" — next to the yolk —
and "follicular epithelium" — immediately outside the latter; but he
gives no figure showing both these at advanced stages of development.
I doubt their existence. But even if there were two separate epithelial
layers, I fail to understand how both could share in the production of
membranes which lie wholly inside the inner cell layer.

The eggs of Acipenser are altogether unique so far as regards the con-
dition of the membrane in the micropylar region.

The earliest observer of the micropyle was Kolliker ('57, p. 197),
who incidentally remarks that there is a single micropyle in the stur-
geon's egg ; but subsequent observers have claimed that there is a group
of several micropyles.

Kowalevsky, Owsjannikow und Wagner ('70, p. 172) state that
at one pole of the egg there are seven micropylar openings, — one in the
centre, with the other six arranged in a circle around the first.

Salensky ('81, pp. 235, 23G, Planche XV. Fig. 1 A) gives a more com-
plete account of the micropylar region, which is illustrated by figures.
He says : " At the germinative pole of the egg there is found a micropyle.

vol. xix. — no. 1. 5

66 BULLETIN OF THE

The orifices of the micropyle are so small on hardened eggs that it is
probable that they are narrowed by the action of the reagents, which
also cause a retraction of the capsule of the egg. For this reason it is
very difficult to find these orifices."

The micropylar apparatus is composed of several (5 to 13) orifices,
and Salensky states that, although he has examined a great number of
eggs, he has never found two which were identical either in the number-
or distribution of the orifices. " Each orifice consists of a quite small
pit (fossette) having the form of a crater ; it is surrounded by small,
very slender cylinders."

Salensky has given only surface views of the micropylar region, but it
has occurred to me that his " very slender cylinders " may be villi which
surround the crater-like depression. They would appear to have a radial
arrangement about the crater as a centre, if the villous layer were seen in
optical section at a plane a little below the outer margin of the crater.

d. Dipnoi.

The conclusions reached by Beddard ('86*) relative to the ova of
Lepidosiren possibly rest on too limited material to receive immediate
acceptance. So far as regards the egg membranes, the story is certainly
far from being satisfactorily completed. In the youngest eggs there was
no trace of any membrane ; but as development proceeded, a delicate
homogeneous membrane encircled the ovum. This was from analogy
thought to be the product of the egg protoplasm, even though it was
more firmly adherent to the follicular epithelium than to the ovum,
and it is called vitelline membrane. In more mature ova there was
underneath this a much thicker radially striate membrane, probably
corresponding to the zona radiata of other vertebrates, which in places
seemed to pass gradually into the substance of the protoplasm. This
membrane (zona radiata) began to disappear with the first steps in the
formation of yolk. During the period of yolk formation the vitelline
membrane became thicker, and also radially and coarsely striate. The
author believes that there was a stage which succeeded this, during
which there was no membrane of any kind, and that at this time an
immense number of follicular cells migrated into the yolk. But in
addition there followed still another stage, — when the ovum was en-
tirely occupied by yolk, — in which the epithelium was separated from
the contents of the ovum by an extremely delicate homogeneous mem-
brane, which either corresponded (in some cases) to the persistent vitel-
line membrane, or (in other cases) was a new formation ; but even in

MUSEUM OF COMPARATIVE ZOOLOGY. 67

the latter case the author maintains that it is homologous with the
vitelline membrane !

The fact that the layer called by Beddard vitelline membrane becomes
radially and coarsely striate, suggests comparison with the villous layer
of Lepidosteus. As in the ganoid, so in Lepidosiren this is the layer
which is produced first.

e. Teleostei.

The numerous descriptions which have been given of the egg mem-
branes in different osseous fishes show that there is not uniformity either
in their number or structure. Besides the wall of the follicle with its
epithelium, the granulosa, there is perhaps only one investment of the
egg which is universally present, the zona radiata, and even this may
be wanting, or at least may wholly disappear in the case of certain
viviparous fishes. I believe it is certain that the homologue of the zona
radiata is invariably present in oviparous fishes, and I am likewise
of opinion, notwithstanding the inability of some observers to discover
the presence of pore-canals in the eggs of certain fishes, that the canals
are also always present.

In many cases there is a membrane intervening between the zona and
the granulosa, sometimes thin and homogeneous, at other times of a
more complicated nature. It may even (villous layer) resemble some-
what the zona itself, although in reality very different from it in struc-
ture. Whether the thin homogeneous layer is homologous with the
more complicated villous layer cannot as yet be definitely answered, but
Balfour's account of the origin of a similar structureless membrane in
Elasmobranchs makes me incline to the belief that it is.

In addition, the cells of the granulosa undergo in some instances a
remarkable metamorphosis, accompanied probably by a process of secre-
tion, and thus furnish still another primary envelope to the ovum.

As to the existence of membranous structures inside the zona radiata,
there is much less certainty. The presence of a structureless vitelline
membrane has been maintained with more or less confidence by Vogt,
Aubert, Thomson, Lereboullet, Kolliker, Eimer, and others, and more
recently by Owsjannikow and Scharff. Its existence has also been
denied by eminent authority.

The question as to the presence and nature of a so called zonoid layer
seems, especially in the light of Brock's recent contributions, to demand
a more extended and thorough investigation. In the case of some of
the eggs studied by Eigenmann ('90), structural conditions have been

68 BULLETIN OF THE

observed which can hardly bear any other interpretation than that of a
striate zone of substance inside the zona radiata proper ; but in other
cases (Esox, Amiurus) a somewhat similar though perhaps not identical
appearance is due to a retraction of the vitellus from the zona, which
leaves strands of vitelline substance stretching across the space thus
produced.

1. Zona Radiata and Villous Layer.

Johannes Muller ('54) has often been credited with having discov-
ered the fine radial canals which traverse the zona radiata, and give to it
its most characteristic appearance. This is a mistake which has arisen
from Midler's misunderstanding the relation of the peculiar membranes
of the perch to those of other fishes. What he described as " pore-
canals " in Perca belonged to a much thicker membrane than the zona.
This membrane lies outside the latter, and is a result of the activity
aud metamorphosis of the granulosa cells. Midler, it is true, supposed
this to be the equivalent of the " shell membrane " previously described
by Vogt, and therefore imagined that he had been able to demonstrate
on a more favorable object what Vogt had claimed on grounds of analogy
rather than on satisfactory proof.

In Vogt's studies on Coregonus palcea he ('42, pp. 1, 8-10, 27, 28)
claimed the presence of two membranes. The inner one — being thin,
transparent, and without apparent texture — he called vitelline mem-
brane ; the outer one he called a shell membrane, and homologized it
with the "membrane coquilliere " of birds' eggs. This outer membrane
presented the appearance of shagreen, which seemed to result from a
quantity of small opaque points uniformly distributed over its surface.
Treated with hydrochloric acid, the points became more transparent,
and then resembled minute warts. Valentine called Vogt's attention to
the resemblance between this structure and that of the carapace of the
cray-fish, where he had found that a similar effect was due to perpen-
dicular tubes, filled with lime, traversing a membrane composed of regu-
larly polyhedral cells. Vogt, admitting that the "shell membrane " was
too thin to allow the attainment of exact results relative to the nature
of the "points," nevertheless claimed that the position, behavior, and
reticulate appearance of the latter warranted one in supposing that the
structure was analogous to that of the carapace of the cray-fish. Thus
it appears, he continues, that the shell membrane is formed by the union
of flattened cells, which are arranged around the primitive egg only
toward the epoch of its maturity ; the presence of these minute tubes,

MUSEUM OF COMPARATIVE ZOOLOGY. 69

which traverse the membrane, would in his opinion sufficiently explain
the absorption of the water into the interior of the shell membrane.
(Compare also Vogt, '42, pp. 27, 28.)

From this summary it is evident that Vogt had under consideration
appearances which were due to the pore-canals of the zona radiata, and
that he moreover believed in the presence of canals, but it cannot be
claimed that he demonstrated their existence. Unlike his predecessors,
he rightly claims that the shell membrane (in Salmo umbla) originates
in the ovary.

In a paper written in 1845, but not published till many years later,
Vogt et Pappenheim ('59, pp. 357, 361, 3G2) also maintain that the
shell membrane of the eggs of fishes, wThich is uniform and elastic, is
constituted by the fusion of a cell layer formed in the ovary, and there-
fore not to be compared with shell membranes which are produced in
the oviduct. They made the mistake of insisting that " this cell layer
is not to be confounded with another epithelial layer which one finds in
the ovisacs of the youngest ovules, and which is composed of large ex-
tremely pale cells which subsequently disappear and give place to this
second layer."

Meckel von Hemsbach ('52, p. 421, Taf. XV. Fig. 1) saw and fig-
ured a radial structure of the "zona pellucida " in the case of Cy-
prinus auratus, after treating the membrane with acetic acid and
crushing it, but he expresses no opinion as to the real nature of the
striation.

Leuckart ('53, pp. 796, 797), who probably had not yet seen Meckel's
paper, was evidently not impressed with the explanation which Vogt
adopted to explain the appearance of the outer membrane in Coregonus ;
for he says simply, " That which characterizes the eggs of teleosts is
the possession of a special firm egg-shell (chorion), which is already
formed in the follicle around the primitive yolk membrane, and generally
presents a delicate marking resulting from regularly grouped granules
or points."

During the five years beginning with 1853 there appeared a large
number of papers dealing with the egg membranes of fishes, and the
subject was brought to a temporary conclusion by the thorough work
of Kijlliker.

Aubert ('53, pp. 94, 95, Taf. VI. Fig. 1) was the first to figure well
the appearances due to the pore-canals of the zona radiata. In addition
to " a very finely granular, but otherwise structureless skin, which en-
velops the yolk," and which I believe must have been in his opinion the

70 BULLETIN OF THE

vitelline membrane.1 Aubert describes the "shell" of the egg of Esox as
a transparent thin membrane, furnished with fine points, which closely
envelops the yolk. These points exhibit a great regularity of arrange-
ment, being placed at the intersection of symmetrical curved lines.
When the shell has lain some time in water, it separates in many places
into two membranes, of which the outer is very thin, finely granular,
and irregularly elevated, while the inner is thicker, uniform, and upon
sections exhibits fine radially placed streaks.

I believe it is certain that the radial streaks described were due to
the pore-canals, although the author does not fully commit himself to
that view. " The spermatozoa are so large," he says, " that it would be
difficult for them to pass through the ' points ' of the shell, in case the
latter are regarded as the lumina of fine canals."

Also Lereboullet ('54, pp. 240, 242, 245, 249) wrote concerning the
pike : " The ripe egg is surrounded by two membranes : the external is
pierced by microscopic tubes, which serve for the absorption of water,
and consequently for the respiration of the egg ; tne internal, applied
to the vitellus, is a simple, extremely thin and amorphous protecting
envelope." He also saw the pore-canals in the perch, and argued that
the expulsion of albuminous globules from the fertilized egg proved
the absence of a vitelline membrane at that time, and that it went to
confirm the opinion of those who regarded the chorion as produced by
the primitive vitelline membrane, which was itself detached from the
vitellus.

Although J. Muller ('54) contributed much to the knowledge of the
egg membranes, especially of the perch, and was also the first to appre-
ciate the importance of the difference in origin between the egg-shell in
birds and what he called the " egg capsule " in fishes, he did not fully
comprehend the structure of what he called the "Dotterhaut" (zona).

1 I cannot agree with His (73, p. 2, foot-note, compare also p. 14) in his criti-
cism of Aubert when he says: " Der Name Dotterhaut, welclien die friiheren
Schriftsteller fur eine besondere den Dotter unmittelbar umhiillende structurlose
Membran gebraucht haben, urird von H . Aubert (Beitrage, etc., 94) oaf die Eikapsel
nngewendet. Er spricht namlich bein Hecht-Ei von einer Trennung der Dotter-
haut [!] in zwei Schichten, eine iiussere diinne, fein granulirte und eine innere,
dieke, mit radiaren Streifen. Eine Begrundung seiner abweichenden Bezeich-
nungsweise giebt er nicht."

Aubert says distinctly enough that it is the " Schale " which is divided into two
membranes ; and although he nowhere employs the word " Dotterhaut," there seems to
me no doubt that he has Dotterhaut in mind when he says : " Der Dotter wird
von einer sehr fein kornigen, sonst structurlosen Haut iiherzogen." His may have
been misled by the statement that "Die Schale etc. den Dotter eng umgibt."

MUUSEM OF COMPARATIVE ZOOLOGY. 71

He claimed for Cyprinus erythrophthalmus, Perca fluviatilis,and Acerina
vulgaris a velvety appearance of the external surface of this membrane
" as if beset with tufts " (Zotten J), which he ascribed to " very small cy-
lindrical projections or rods with rounded ends," — prolongations of the
vitelline membrane itself. Here again Miiller unfortunately confounded
the unlike conditions of different eggs. While his conclusions have been
confirmed in the case of Cyprinus erythrophthalmus, I know of only one
author whose observations give any evidence of the presence of such a
" pile " or velvety structure outside the zona in either of the other fishes
mentioned. Hoffmann ('81, pp. 19, 20, Taf. I. Figs. 9, 10), it is true, not
only figures an external layer of the zona in a nearly ripe egg of Perca,
which is thinner and much more sparsely striate than its inner layer, but
he also describes and figures an October egg as possessing outside the still
thin zona a layer of minute, close-set tubercular projections which " fully
correspond to the Zottchen of the Cyprinoids." I believe that Hoff-
mann has in some unaccountable way fallen into an error in this matter.
At least, no other observer has seen any trace of the structure which he
describes, and an examination of the eggs of our American perch in
October reveals nothing of the kind. I think the condition in Acerina
is probably similar to that in Perca, — certainly no one has shown the
presence of a " Zottchen " layer. That being the case, what was if
that Miiller mistook in Perca and Acerina for " Zottchen " 1 A state-
ment by Owsjannikow ('85, p. 18) makes me believe that Miiller may
have had under view the branching deep ends of the tubular structures
which according to Owsjannikow traverse the gelatinous envelope, and
which are left sticking in the pore-canals of the zona when the two
layers are artificially separated. It may be, however, that Miiller saw
the more conspicuously — but not, as Hoffmann makes it, more sjiarsely
— striated outer portion of the zona itself, in which event it might be

1 Miiller was not the first to see the appearance presented by these "Zotten,"
ar even to suggest the name. Von Baer ('35, p. 7) had, twenty years before,
seen the same thing in species of carp. " Die aussere Eihaut ist aber nicht
ganz formlos und gleichartig in sich. Sie enthalt in den Karpfenarten, die ich zu
untersuchen Gelegenheit hatte, keine [should be Heine] dunkleren Vorragungen, die
ihr bei starker Vergrosserung ein zoitiges Ansehen gaben." It is evident that Von
Baer confounded the radial " tubes " in the outer envelope of the perch egg with
these villi of the carps, for he adds : " Im Barsche ist diese Hiille noch sehr viel
dicker und man sieht, dass die dunklern Flecken, die hier lang und schmal sind, in
der iiussersten Schicht sich befinden." One will find little occasion for surprise at
this parallelism, in view of the fact that some of the most recent observers, with
the best modern appliances at command, have arrived at a similar, though I believe
erroneous conclusion.

72 BULLETIN OF THE

fairly claimed that he had seen the pore-canals ; but even in that case
it remains perfectly evident that he did not understand at all the
structure of the zona radiata.

When, a few months later, Remak ('54) announced the discovery of
radial striations traversing the whole thickness of the zona pellucida in
the case of the rabbit's egg, and attempted to determine the cause of
the appearance by a comparison with the conditions found in the egg
membrane of a fish (presumably Gobio fluviatilis), Miiller ('54a, p. 256)
was unable to agree with him in the conclusion that the appearance was
probably due to "an alternation of canals and cylinders," but en-
deavored to show that it was " merely an optical expression of the sum-
mation and partial superposition of the images of the rods [Zapfen] as
seen when viewing the vitelline membrane in profile." The images of
the overlying rods which fall in one line would, in his opinion, cause
the striations to appear much longer than the individual rods really
were, and thus make the lines appear to traverse the whole thickness
of the membrane.

Ransom ('56) maintained that there was present at an early stage
in the growth of the ovum of Gasterosteus a very thin membrane, hav-
ing a finely and regularly dotted structure ; but he does not appear to
have realized as yet that the dots were evidence of pore-canals. He also
discovered that in older eggs the part of the membrane immediately
surrounding the micropylar depression exhibited a number of cup-
shaped pcdiculated bodies scattered over its surface. These have since
been claimed by Kblliker ('58, p. 81) and subsequent authors to be the
localized equivalents of the " Zapfen " layer discovered by Miiller.

In the same category must also be placed the remarkable filamentous
structures discovered by Haeckel ('55) on the eggs of several of the
Scomberesocidse. Although Haeckel described the filaments as lying
inside the finely punctate vitelline membrane (zona radiata) and having
no connection either with it or the yolk, there can be no doubt, as
Kolliker ('58, p. 81) first showed, that they are really outside the zona.
I have not yet had the opportunity of examining the eggs of any of the
Scomberesocidse, but conjecture that the sheath which envelops the bases
of their filaments may be only a part of a membrane external to the
true zona radiata, and comparable with that which Eigenmann ('90)
has found in Fundulus.

Leuckart ('55, pp. 257-264), who in an appendix to his celebrated
paper on the micropyle of insects' eggs deals, at least incidentally, with
the structure of the egg membranes in fishes, was the first to perceive

MUSEUM OF COMPARATIVE ZOOLOGY. 73

the true significance of Miiller's discoveries in the perch. He retained the
name chorion for the zona radiata, and from a study of the trout was
fully convinced that the punctate appearance is due to " delicate tubules
or canals which traverse the membrane perpendicularly, without open-
ing, however, at its inner surface." The latter part of this statement
has not been confirmed by subsequent observers. Leuckart, however,
gave an excellent description of the structure of the zona radiata in the
perch, for he not only recognized that it was composed of an outer thin-
ner, firmer membrane, and an inner thick layer of viscid sarcode-like
substance, but he also saw that the two layers were so intimately joined
to each other that the canals were continued through both. While I
prefer to regard these two layers as substantially a unit, basing my con-
clusions on a variability in the apparent independence of the outer layer
and on the continuity of the pore-canals through both, I recognize that
this is a minor point, and that already Leuckart was in possession of the
important facts of structure. It was the presence of this " chorion " in
addition to Miiller's capsule with its coarser pore-canals which convinced
Leuckart that the latter could not be considered the equivalent of the
radially striate membrane in other fishes, such as the salmon and trout.
I believe that Leuckart was less fortunate when he concluded that there
was in Esox a layer immediately outside the " chorion " which was homol-
ogous with the Miillerian " capsule " of the perch ; for in my opinion
there can be no doubt that the layer in question is the same as that in
which Eigenmann has found the pore-canals to be continuous with those
of the deeper portion of the zona. Even Leuckart describes the canals
as straight, not spiral as in Perca. In my judgment, therefore, this layer
corresponds to the thin outer layer of the zona seen by Leuckart in the
perch, rather than to the capsular layer described by Miiller.

Although Volume V. (Supplementary Volume) of Todd's Cyclopedia of
Anatomy and Physiology was not issued until 1859, the article " Ovum"
by Allen Thomson was published much earlier, and in two parts, ac-
cording, to Gegenbaur ('61, p. 495). The first part (pp. 1-80) appeared
in 1852, and the second part (pp. [81]-[142]), which contains the por-
tion devoted to osseous fishes, in 1855.

Thomson ('59, pp. [99],' [100], [103]), besides giving a very brief
summary of previous work on the subject, treated at some length the
structure of the zona radiata, basing his conclusions partly on the work
of Ransom and partly on his own studies. On the strength of Eansom's
work he claimed that " the structure [Eikapsel] described by Miiller in
the perch was peculiar to that fish, and belonged only to an outer cover-

74 BULLETIN OF THE

ing superadded to the surface of the dotted membrane, which last re-
sembles in all respects that of other fishes." "This outer covering," he
adds, " appears to be of cellular origin ; and Dr. Ransom thinks it may
be due to the separation of the tunica granulosa along with the ovum."
Thomson was able " to perceive the circle or lumen of the tubes " in
the dotted membrane by using a high magnifying power, and also
thought he could distinguish a hexagonal marking of the intervals be-
tween the pores (which he figures) in the salmon ; he also pointed out
that the size of these pores was only about one third of that of the tubes
in the perch as described by M tiller. The author was less successful,
when, in explaining Fig. 67*, he said: "A granular or dotted appear-
ance of these [granulosa] cells seems to indicate their conversion into
the dotted membrane, which is probably formed in successive layers from
the exterior. . . . The ovum (p. [103]) receives its firm porous mem-
brane [zona] while within the ovarian capsule, but only in the latter
part of the time of its formation." The origin of the membrane he
is incliued to connect with the interior of the ovarian follicle ; " but
whether by exudation from it, or by amalgamation of the innermost layer
of epithelial cells of the follicle," he has not been able to determine.
The latter he believes the more probable, and that -the membrane is the
true vitelline membrane. I am entirely unable to comprehend how
Thomson could have reconciled the two statements in the last sentence,
for surely the vitelline membrane was not, even at that time, regarded
as the product of anything but the ovum itself.

On ripe fish-eggs Eeichert ('56, p. 89) was able to distinguish two
membranes, both of which were formed within the follicle. The inner
was the punctate membrane, but owing to the fineness of the markings
it was impossible to determine whether they were the result of elevations
or depressions of the surface. Reichert was unable to adopt without
reserve the conclusion that the dotted appearance is due to radial canals,
even though such an explanation was suggested by his finding the mark-
ings on the inner as well as the outer surface of the membrane in the
case of Cyprinus carpio. He evidently reposes great confidence in
Midler's explanation of the striation as an optical illusion, which in his
opinion accounts for the appearances figured by Aubert. He is also
uncertain in regard to the existence of a vitelline membrane, so that a
positive conclusion as to the nature of the zona radiata was not reached.
The smallest eggs possess a transparent homogeneous membrane without
punctations, and too thin to be measured, which may be regarded as a
vitelline membrane. With an increase in the size of the egg this mem-

MUSEUM OF COMPARATIVE ZOOLOGY. 75

brane becomes thicker, and in Acerina punctate markings become visible
on its outer surface when it is only about 2.8 /x thick. There is never
any appearance which allows the supposition that the thickening is pro-
duced by secretions from the epithelium of the follicle. Since the punc-
tate appearance becomes visible only after the thickening of the original
membrane, it is to be concluded, says Reichert, that the punctate mem-
brane of the ripe egg is not the original vitelline membrane, but a
secondary egg-membrane, which, however, has been formed by the depo-
sition of thickened layers (" Verdickungschichten ") of the egg outside
the vitelline membrane. But what has meantime become of the vitelline
membrane is nut stated.

Keichert distinguished on the majority of the eggs which he studied a
second membrane outside the punctate one. In Esox it was clear, homo-
geneous, and viscid. In cyprinoids it had the velvety appearance already
described by Midler, from whom the author differs in regarding this
membrane as not a part of the punctate one. His reasons for this con-
clusion are, that it is as sharply marked from the punctate membrane
as is the capsular membrane in the perch and may even be detached
after treatment with chromic or nitric acids, that the rod-layer is not so
firm as the punctate, and finally that the rods are much fewer than the
punctations of the same egg. The rods are set in a clear, homogeneous
layer, only their rounded ends protruding.

Reichert was evidently influenced by his belief in the probability that
the capsular membrane in the perch owed its origin to the membrana
granulosa, and consequently he left unsettled the question of the origin
of this villous layer, although its intimate adhesion to the punctate
membrane indicated a common origin with the latter.

Kolliker ('57, p. 197) found in 185G that the porous membrane in
the case of sturgeons' eggs presented conditions which favored the view
that it was formed by the cells of the follicle, but he discreetly abstained
from forming an ultimate judgment before eggs in all stages of develop-
ment had been studied. Such studies he found the opportunity of be-
ginning during a sojourn at Nice a few months later, and he continued
them on fresh-water fishes during the beginning of the following year •
the results were published in 1858.

Kolliker's ('58, pp. 80-93) observations embraced a large number
of fishes, and — what is of more importance — he also studied eggs in
several stages of development. With Reichert, he recognized two cap-
sular egg membranes, which he called " Dotterhaut " (zona radiata) and
" Gallerthulle" (the latter in Perca), but he dissented from Reichert's

76 BULLETIN OF THE

explanation of the striate appearance of the former, and demonstrated
by means of thin sections that it was due to the presence of pore-canals.
Kolliker also claimed that there was an outer thin, resistant layer of
the porous vitelline membrane in the case of all fishes, — such as
Leuckart alone had recognized in Perca, — and that this layer might
retain the striate appearance even when the rest of the membrane had
been made pale and apparently homogeneous by the use of reagents.
It is in this outer layer that the viscid and fatty-looking "Zottchen''
are rooted with their slightly enlarged bases. Kolliker therefore re-
gards the " Zottchen " layer as belonging to the " Dotterhaut," rather
than as a separate layer, and compares its elements to the peculiar
appendages discovered by Haeckel in the ScomberesocidEe. To these
he adds a description of peculiar mushroom-shaped appendages of the
vitelline membrane in Gastei-osteus and Cottus gobio. There is, how-
ever, one difference between the "Zottchen" and the mushroom-shaped
bodies ; in caustic potash the former are greatly swollen and become
pale, whereas the latter are made to shrink somewhat and to become
darker.

In reference to the origin of this membrane and its appendages,
Kolliker gives the first positive information which we have, for Eei-
chert's conclusions were at best only theoretical and tentative. Both
in the case of Gasterosteus and Cobitus barbatula he showed that the
villous structures made their appearance before the zona radiata. In
the case of the first-mentioned species, the mushroom-shaped bodies
were distinguishable as minute wart-like points resting on the outer
surface of a membrane so thin that it presented only a single contour.
As these wart-like structures continue to occupy the outer surface of
this vitelline membrane while the latter increases in thickness, it is not
to be doubted, he says, that the increase is due to deposits upon the
inner surface of the membrane. The warts continue to increase in size,
while the membrane becomes still thicker and shows radial markings.

The first appearance of the villi in Cobitis is to be seen in eggs
0.08" [0.08'"]= 175 /x] in diameter, where they appear as deposits or
outgrowths on the external surface of a thin membrane (Reichert's primi-
tive vitelline membrane) ; at first they are low and narrow, but they
gradually increase in length, and also, though more slowly, in breadth.
It is only when the villi have attained their full length that the porous
layer begins to be formed by deposits on the inner surface of the thin
membrane, but this proceeds with such energy that the porous layer
soon exceeds in thickness the villous. At the same time the villi in-

MUSEUM OF COMPARATIVE ZOOLOGY. 77

crease in breadth, though not in length, and the thin membrane persists
as the outer layer of the porous membrane, which in the ripe egg bears
the villi. Upon the first formation of the villi the appearance of a sur-
face view of the membrane so closely resembles that of a porous vitelline
membrane (zona radiata) with fine close-set pores, that one must follow
the whole course of development, and convince himself of the late ap-
pearance of the porous layer before he can be certain that the fine points
are due to the villi.

Kolliker believed that the formation of this peculiar "Dotterhaut"
(zona radiata) of fishes could be easily understood as one of the so
called secondary cell secretions, if there were on the inner side of it
another membrane, which latter would then be regarded as the origi-
nal cell membrane of the egg. Although he found some evidence of
the existence of such a thin structureless membrane in Cobitis, he
was unwilling to give much importance to that fact, but inclined to a
belief in its existence, rather upon the theoretical ground that it would
offer a satisfactory explanation of the radial pores as being the equiva-
lents of pores in cuticular structures.

This assumption (p. 104) that the fine pore-canals are to be explained
as resulting from the presence of fine openings in the cell membrane
may be satisfactory enough for those cases in which a definite cell
membrane is demonstrable previous to the appearance of the cuticular
secretion ; but it seems to me superfluous to assume the universal exist-
ence of a cell membrane in order to explain the conditions. Where no
cell membrane exists, the same phenomenon may take place, and is no
more difficult of explanation than in the case where there is a cell
membrane with the supposed structure; for the latter must in its turn
be explained as the result of localized activity on the part of the cell
pi'otoplasm in secreting its membrane. So, in the end, it comes to one
and the same thing, whether we assume the presence of a cell membrane
or not : the explanation must rest on the ability of protoplasm to
localize its activities ; but further than that we are at present unable
to advance. Why or just how protoplasm is able to effect such a histo-
logical division of labor is still unexplained.

The important paper by Gegenbaur ('61) on the structure and devel-
opment of the vertebrate ovum adds nothing to our knowledge of the
zona radiata in bony fishes, but is valuable for the way in which it
illuminates the subject of the vitelline membrane.

The only articles of much importance during this decade were one by
Buchholz and two by Ransom.

78 BULLETIN OF THE

Rathke's ('61) posthumous work on the development of vertebrates
evidently treats the subject from the standpoint of thirty years before,
when little was known about the matter ; and

Lereboullet ('61, pp. 120, 121, 123) does not greatly add to the
knowledge of the zona radiata when he says that the chorion of the
trout egg is thin and very soft at the moment the egg is laid, and does
not present the resistance and elasticity which it acquires after it has
remained for some time in the water. For the absorption of water and
the passage of gases necessary for the respiration of the egg and em-
bryo, the chorion is pierced, he says, by an infinite number of excessively
narrow, short parallel tubes, which give a striate appearance to perpen-
dicular sections of the shell.

Owen ('66, pp. 593-595), although following the accounts by Ran-
som and Thomson, fails to recognize one of the important points estab-
lished by the latter author, for he does not distinguish between the
" ectosac " in the perch, and that of salmon and other fishes. More-
over, this " ectosac " (evidently the zona radiata) " is composed of close-
set series of hollow columns." (!) As Ransom ('67, p. 3) has since
pointed out, Owen also erroneously states, possibly under the influence
of Rathke's exposition, that the villi are formed after the ova escape into
the cavity of the ovary.

Buchholz ('63, pp. 71-81, and 63a, pp. 367-372) was the first to
describe a very peculiar appearance of the egg membranes in Osmerus
eperlanus. In addition to the porous membrane (zona radiata), which
continues to invest the egg after it is laid, there is a second one external
to thj first, and like it traversed by similar pore-canals. Buchholz states
that these canals are much more readily recognized to be pore-canals in
the case of this fish than in that of other fishes (p. 73). When the egg-
has lain for some time in water, the outer envelope, or at least a portion
of it, is found to be attached to the inner membrane around the circum-
ference of the micropylar canal, whence it depends as a loose funnel-
shaped frill with its originally inner surface now directed outward. The
pore-canals which traverse these two membranes, instead of being cylin-
drical, are funnel-shaped, the wider end being directed outward. By
treating the fresh ovarian egg with acetic acid the outer membrane,
which at first lies closely in contact with the inner, is made to swell
up with irregular foldings until it becomes entirely separated from the
inner ; but a striate appearance, which is visible for a moment, becomes
quickly obliterated by the action of the acid. If, however, the eggs
are first treated for twenty-four hours with very dilute chromic acid,

MUSEUM OF COMPARATIVE ZOOLOGY. 79

and then with acetic acid, the radiate structure remains easily distin-
guishable in both membranes.

With regard to the formation of the two membranes, Buchholz argues
that the outer is the older, since one often finds, in the earlier stages of
their formation, that the inner is thinner than the outer, whereas subse-
quently they are both of equal thickness. The increase in the thickness
of the inner membrane was observed between the middle of February
and the middle of April, — the spawning time, — and meanwhile the
outer membrane was found to be thinner over about one third of the
surface. It is to be assumed, according to Jie author, that this attenu-
ated portion finally disappears altogether, since the persistent portion
which remains attached in the region of the micropyle is too small to
have completely enveloped the egg. Even nearly up to the time of
maturity there is no fusion between the two membranes, which must,
therefore, take place rather late.

The homology of the outer membrane in Osmerus is not at once
evident from this account by Buchholz. If one were to accept un-
questioned his description, it would be most natural to regard it simply
as a detached portion of the zona radiata, for he maintains that the two
are identical in structure. There are, however, two other possibilities ;
it may be homologous either with the villous layer of Lepidosteus, or with
the capsular envelope of the perch. I regret that I have not yet found
the opportunity to acquire from personal study additional evidence in
favor of one or the other of these explanations ; but there are two or
three things connected with the account given which incline me to
believe that the outer membrane is the equivalent of the villous layer.
The very fact of its becoming detached from the deeper layer and
thrown into folds after the egg has lain in the water suggests a similar
though less striking feature of the villous layer in Lepidosteus ; and al-
though there is no evidence that any such eversion of the membrane
takes place in the latter case, or that it eve:: becomes regularly attenu-
ated on one side, as in the case of Osmerus, still I can imagine that a
similar condition might be artificially produced in Lepidosteus, so far at
least as regards the peeling off and eversion of the outer covering, and
it is possible that a slightly different physical condition of the villi
would cause them to adhere to each other so persistently as to allow the
attenuation of the whole membrane on one side of the egg without
separating the individual elements. Since Buchholz asserts that the
pore-canals are more readily distinguished as such in this fish than in
other instances, I infer that the markings which he observed must have

80 BULLETIN OF THE

been coarser than is usual. If his attention was mainly directed to the
outer layer, and if, as I imagine, this is a villous layer, the reason of his
statement would be obvious. Besides, he mentions that the canals are
not cylindrical, but funnel-shaped, the wider end outermost ; this, too,
though suggestive of the capsular membrane, would be entirely com-
patible with the idea that he had under view club-shaped villi. And
finally, the argument to show that the inner layer is produced after the
formation of the outer is exactly applicable in the case of the villous
layer, as the observations of Kblliker and my own conclusively show.

Ransom's ('67) account of the "yelk-sac" (zona radiata) in Gas-
terosteus is principally interesting to me from his asserting that the
pore-canals as well as the villi increase in number during the growth of
the egg, and from his consequent conclusions as to the method in which
membranes are formed. The "yelk-sac," he says, is formed in very
young ova (^JV'j or 125/*, in diameter), in which it is easily recognized
by the button-shaped villi attached to the outer surface surrounding the
micropyle. The finely dotted structure is first discoverable in eggs xkrs"
(180 //.) in diameter, and it is the same in character in these as in the
ripest eggs. The membrane is composed of very fine concentrically
arranged laminae, each of which is marked by dots of equal size, so
arranged as to mark (in surface view) the angles of equal -sized lozenge-
shaped spaces, and corresponding in position in the successive laminae so
as to form vertically placed lines or stria?. In eggs .01 inch in diam-
eter there were about 24,000 dots to the [linear] inch, and when the
egg had attained .06 inch there were 11,000 to the inch; the distance
between dots being scarcely more than doubled, while the diameter of
the egg had been multiplied about six times. From this the author
argues that there must have been an increase in the number of the dots
during the growth of the sac, and therefore that the membrane does
not increase by apposition of layers either from the inside or outside,
either by the hardening of an exudation or by the conversion of the
substance of the yolk into that of the yolk-sac. " It grows in some
way by interstitial molecular deposit." A similar increase in the num-
ber of the button-shaped villi was also observed to occur during the
development of the ova.

I do not recall that any one has corroborated or disproved these ob-
servations, or the deductions made from them ; but I have shown that
in the case of Lepidosteus there does not seem to be sufficient evidence
to prove that there is any increase in the number of the villi. I believe
that a careful investigation of the question in the case of the pore-canals

MUSEUM OF COMPARATIVE ZOOLOGY. 81

would well repay one who should undertake it, for it could not be without
influence upon theories on the method of the growth of membranes.

In his more extended paper Ransom ('68) gives an account of the
egg membranes of a number of fishes, but more particularly of Gaste-
rosteus, Esox, and Perca. To what he had already stated about the
" yelk-sac " of Gasterosteus he adds (pp. 440, 444, 448) that it is diffi-
cult, if not impossible, to determine the precise period at which it is
formed. In eggs ^Jn" (31.5 jx) in diameter it is not found, but is prob-
ably indicated by the smooth, hard outline which the yolk shows on its
surface. " It is separable in eggs ^ W in diameter, and may be seen in
the fluids on the slide as a homogeneous-looking collapsed sac." With
a power of 500 diameters the dots appear round, and with one of 3,000
they are but obscurely hexagonal ; they are the same distance apart on
the inner surface as on the outer. Besides these minute regular dots,
there are larger and darker ones of a stellate form, which the author
suggests may in some way be connected with the interstitial growth of
the membrane. They occur irregularly at intervals of about 3^<j"> an<l
act like bodies of low refractive power; "at the cut edge they may be
seen to pass radially about two thirds into the substance of the yelk-sac,
gradually coming to a point and ceasing." I am not aware that any
other observer has confirmed this appearance, which I imagine may be
due to the presence of protoplasmic prolongations of the yolk into some
of the pore-canals, just as in Lepidosteus the substance of the villi is
traceable in many cases for some distance into the zona, although from
the opposite direction.

"There are no facts known to me," says Ransom, "to point out
whether the pabulum for the growth of this membrane is derived di-
rectly from the currents passing inwards, or from the material elaborated
in the egg and passing out of it, or from both sources indifferently."

Waldeyer ('70, pp. 80, 81, 83), however, did not experience any such
uncertainty concerning the source of the zona radiata, for while he con-
tinued to call it the " Dotterhaut " and could find no vitelline membrane
inside it, he was very explicit in stating that it was a cuticular formation
produced by the follicular epithelium, and that the pore-canals were occu-
pied by delicate protoplasmic filaments which were in direct connection
with the epithelial cells of the follicle on the one side, and with the finely
granular yolk substance on the other. In his general conclusions con-
cerning the eggs of vertebrates he says : " The complete homology of the
zona pellucida [mammals] with the vitelline membrane of other verte-
brates can ... no longer be denied. The vitelline membrane is cer-

VOL. XIX. — NO. 1. 6

82 BULLETIN OF THE

tainly a structure which does not belong to the primordial egg, but is
deposited upon it from without."

Like Waldeyer, Eimer (72% pp. 417-428, Taf. XVIII. Figs. 9-13)
regards the zona as a cuticular product, but, unlike him, he maintains that
it is produced (precisely as in reptiles) by the egg, not by the granulosa.
But the homology between the egg membranes in these two groups goes,
in his opinion, still further. The delicate membrane described by Au-
bert and others as external to the zona in Esox and other fishes is to
be regarded as a chorion, — which in reptiles is produced by the fol-
licular epithelium. The trumpet-shaped structures of the outer mem-
brane (Eikapsel) in the perch are formed from granulosa cells. They
are the homologues of the trumpet-like structures which the author
described for Coluber and placed in the category of "beaker cells."
The villi which repose on the outer surface of the zona are, as held
by Reichert, to be regarded as belonging to the second membrane, and
not in- accordance with Kblliker's views as the outer layer of the zona
itself. In Eimer's opinion they are simply yolk substance which has
emerged from the egg through the pores of the zona. Eimer even main-
tains that he has observed the protrusion and subsequent disappearance
of such villi.

I have already (p. 54) given my reasons for dissenting from the use
which His ('73, pp. 1-3) makes of the word "Eikapsel" to signify the
zona radiata. According to His, the "capsule" in Salmo salar is from 33
to 35 fj. in thickness, the pore-canals are straight, only 1.5 to 2 /x apart,
and not funnel-shaped at either end. In Esox it is 16 to 17 /u. thick,
and has fine parallel (concentric) as well as radial markings (p. 13).

His ('73, pp. 17, 35, 36, et passim) also discovered that in numerous
cases the young eggs possessed a peripheral layer of clear substance
which exhibited fine radial markings after treatment with certain acids.
This did not appear to be constantly present, nor necessarily of uniform
thickness. He called it the zonoid layer, and thought there was proba-
bly a physiological connection between it and the porous egg capsule,
but what the nature of that connection was, remained to be ascertained.
Nothing in either figures or text allows one to draw conclusions as
to the relative fineness of the striations in the zonoid layer and the
" capsule."

In 1878 appeared three papers which dealt with the structure and
development of the egg membranes of bony fishes.

A pupil of Waldeyer, Kolbssnikow (78, pp. 402, 403, 407-409),
states that in both Perca and Gobio the " Dotterhaut " consists of two

MUSEUM OF COMPARATIVE ZOOLOGY, 83

membranes, which are not easily separable either in the fresh state or after
treatment with osmic acid ; but on thin sections of eggs hardened in the
latter reagent or potassic bichromate the two are sharply marked. This
condition is held to indicate a gradual growth of the striate Dotter-
haut, " und zwar ihrer ausseren Stiibchenschicht," which is the youngest
formation, the inner layer being the older. Both layers consist of rods
radially placed side by side, those of the inner layer being much finer,
longer, and nearer together than the outer. It is evident, I believe,
that the inner layer referred to must be the zona radiata, and the outer
the " Eikapsel " of Muller. Fine granules, which are colored black by
the osmic acid and are regarded as yolk granules, are found in the fine
processes between the rods, as well as in the follicular epithelium itself.
When the ovary hardened in alcohol is stained in hematoxylin, the
inner sm-face of the follicular epithelium resembles ciliated epithelium,
since the rods rest like cilia on the epithelium. On sections of a very
young follicle (4.65 fx) the membrane, composed of rods, can be seen on
the inner surface of the follicular epithelium. It is still thin and not
easily detached, and the rods are fine and close together. When the
follicle hao reached, a diameter of 465 li, the membrane is much thicker,
and composed of two layers. It is then to be seen that in some places
the rods of the outer layer are continued into the inner layer, being
consequently longer. In this case the rods gradually diminish in thick-
ness as one passes from the follicular epithelium toward the yolk sub-
stance, but they are always sharply limited from the latter. Both layers,
the author concludes, are cuticular formations of the follicular epithelium,
and in no case is the inner layer to be regarded as a special membrane
produced by the egg itself.

One of the best contributions recently made to this subject is that of
Brock ('78, pp. 547-559), who gives, besides a condensed summary of
previous observations, his own valuable results. Aside from the capsular
membrane of the perch, which he calls " Gallertkapsel," and the related
structures of other fishes, the author is able to recognize only one egg
membrane, which, to avoid prejudging its genetic relation, he calls, from
its most evident morphological peculiarity, the zona radiata, reserving
the term membrana vitellina for egg envelopes, which are the equivalent
of other cell membranes and therefore differentiations of the [egg] proto-
plasm. The outer lamella of the zona described by Reichert and by
Kblliker he finds with varying distinctness in different cases. Being in
some instances unable to discover it at all, he doubts its constancy. It
may often be demonstrated by the use of acetic acid when not visible

84 BULLETIN OF THE

in the fresh condition. In the perch it has a striate appearance, and
is much more coarsely marked than the true zona,1 but in Serranus
hepatus it is homogeneous.

The elongated club-shaped villi resting upon the outer surface of the
zona were found in many cyprinoids, and also in Osmerus. They are
not, as asserted by Eimer, expressed droplets of yolk substance ; they
are secondary appendages of the zona, which " have nothing whatever
to do with either follicular epithelium or yolk." Brock finds the zonoid
layer of His well developed in Alburnus lucidus, Salmo fario, and Perca
fiuviatilis. He is inclined to regard it as a general structural condition,
often overlooked because distinctly shown only at certain periods in the
development of the egg. It is often divisible into two layers, of which
the inner remains homogeneous. When the zona radiata is removed
from the yolk, the " zonoid " remains attached to the latter, to which it
must therefore belong. Its striations are intermediate in fineness be-
tween those of the villous layer and those of the zona. Notwithstanding
certain objections, Brock regards the follicular epithelium as the princi-
pal, if not the exclusive, source of nutrition and growth for the yolk,
which are accomplished by means of cell processes sent by the granulosa
through the zona into the yolk. The evidence, aside from that which
Waldeyer produced fur other groups, is to be found, says Brock, in the
fixct that, when the granulosa is separated from the zona by a secondary
membrane (Perca, Serranus), it sends processes through the latter which
are traceable up to the zona.

According to the opinion which I have formed, however, in regard to
these so called processes, they are not outgrowths from the granulosa
cells ; on the contrary, the cells, retaining their original contact with
the zona, are by the accumulation of the capsular secretion greatly
attenuated.

In regard to the order in which the different membranes make their
appearance, Brock comes to views diametrically opposite to those ex-
pressed by Kblliker. Leaving out of consideration the capsular mem-
brane, which, as Brock rightly states, is late in being formed, and the
outer lamella of the zona, concerning the origin of which he could dis-

1 It is not possible to say with certainty from his figure (Fig. 7, /) whether
Brock regarded the striations of the outer lamella as less numerous than those of
the rest of the zona. They are represented as broader than the latter, and as
thickest at their peripheral ends, which agrees with Eigenmann's observations ;
but they certainly are not represented as continuous with the striations of the inner
portion, and in this I believe that Brock is in error.

MUSEUM OF COMPARATIVE ZOOLOGY. 85

cover nothing, he asserts that he saw in all cases with the greatest
distinctness that the zona radiata first appeared, and that when it
had attained a certain thickness then for the first time the villi and
the zonoid layer made their appearance, almost simultaneously. Un-
fortunately, Brock has given no details concerning the proof of this
assertion, either in figures or description. I am tolerably certain, not-
withstanding the very positive way in which he maintains his conclu-
sion, that Kolliker was right, and that he is wrong, for I cannot believe
that in so fundamental a matter there is such a difference between
fishes as would be implied by admitting both views to be correct.

That the differences of opinion which the egg membranes have given
rise to are not exclusively due to the study of different fishes, is clearly
seen from the results reached by Kupffer, and soon after by Hoffmann,
in the study of the herring's egg. Kupffer ('78a, pp. 177, 178) found
the yolk to be closely invested by an egg capsule 6 to 8 /a in thick-
ness, and the latter to be covered by a layer of viscid semifluid sub-
stance, which was found to be of nearly uniform thickness if the eggs
were dropped into alcohol without contact with water. In water it soon
becomes solid. The capsule consists of two firmly united layers, the
inner one being finely striate radially, and alone equivalent to the po-
rous capsule (zona radiata) of other eggs. The striation is due to pore-
canals. These do not traverse the outer layer, which has concentric
striations. A boiling ten per cent solution of potash dissolves the po-
rous layer quickly, but does not affect the outer layer of the capsule,
which is believed to be the same as that described for Esox by Aubert,
and for other fishes by Kolliker. This difference in the two layers
Kupffer regards as favoring Eimer's view, that one is produced from
the egg and the other from the follicular cells.

On the other hand, Hoffmann ('81, pp. 15-33), who has given the
subject of egg membranes in fishes the most extensive treatment of any
recent writer, differs materially from Kupffer in his account of the her-
ring, although he offers a partial explanation of their differences in
saying that Kupffer examined only fully mature eggs, and such as had
been in contact with sea-water. Hoffmann makes the total thickness of
the membranes in not quite mature eggs to be 32.5 /x. The outer layer,
10 fj. thick, is not separable from the inner, although a dark line marks
the boundary. Both layers are traversed by numerous pore-canals,
which, to judge from his figures, appear to be finer (not necessarily
nearer together) in the inner than in the outer layer; but whether they
are continuous it is impossible to say on account of the sharp line sepa-

86 BULLETIN OF THE

rating the layers. The inner layer is composed of two parts, the outer
part being often striated concentrically. The membrane of the fully
ripe egg is different. Before contact with water the pore-canals of the
outer layer are not so easily distinguishable as in immature eggs, and in
this layer a great number of small lustrous spherules are now visible.
In eggs which have been in contact with sea-water the outer layer is
raised up from the inner, forming a viscid sheet 10-12 /x thick, which
causes the adhesion of the eggs. The outer portion of the inner layer
now exhibits a tendency to split into concentric layers, which obscures
the radial pores, although they are still visible iu the deeper part of
this portion.

It appears to me probable that the two portions of the inner layer
represent the whole of Kupfter's capsule, and that Hoffmann's outer
layer is the equivalent of Kupffer's viscid semifluid substance. In view
of the striate appearance of the outer layer described by Hoffmann. anJ
the greater coarseness of the striatums as compared with the inner layer,
and also in view of its viscid nature, I am strongly inclined to belie- j
the outer layer will ultimately be shown to be equivalent to the villous
layer in other bony fishes.

Two layers resembling those of the herring were also found in Creni-
labrus. Greater iuterest attaches, however, to the account of Leuciscus
rutilus, in which, as the author says, one again finds the two layers of
the zona radiata. But in the next sentence he shows that he does not
distinguish sharply between zona and villous layer : " The outer layer
here forms the well known Zuttchenschicht." The villi are club-shaped,
close set, and clothe the zona as a uniform layer, with the exception of
the place where the micropyle is situated. In the extent of their distri-
bution, therefore, the villi in Leuciscus differ from those of Lepidosteus,
— which, though shorter, are not wanting in the periphery of the micro-
pyle,— and also present a condition which is the complement of that
exhibited by Heliasis, Gobius, etc., in which villous structures are
restricted to the region of the micropyle.

Hoffmann arrives at these general conclusions : In adhesive eggs the
zona radiata consists of two layers, of which the outer effects the ad-
hesion. The latter may form a part of the whole zona, or may exist in
the form of villi over the whole surface, or of long filaments limited to the
micropylar region. " But whatever form this outer layer may assume,
it always has a like origin with the rest of the zona ; it is nothing else
than a part of the zona itself, which sooner or later undergoes peculiar
metamorphoses." Hoffmann recognizes the difficulty of determining how

MUSEUM OF COMPARATIVE ZOOLOGY. 87

the zona radiata arises, whether as a product of the yolk or of the granu-
losa cells. An examination of maturing eggs shows him that its periph-
eral layers are always the most distinct. It is as though new layers
were being deposited from within, and this leads to the conclusion that
the zona radiata represents a true vitelline membrane.

Although Hoffmann seems to me to come very near the true solution
of the problem, this presentation of the matter appears altogether un-
satisfactory, because he insists that what he calls the zona is practically
a unit in structure, and fails to recognize a fundamental difference be-
tween the outer villous layer and the " true zona radiata," as he terms
the inner portion of his zona. From this last conclusion one would be
led to infer that the zona (including both layers) was the result of a con-
tinuous process, and that there could not be any radical structural differ-
ence between villous and poi'ous layer. But to my mind a common origin
from the yolk by no means implies identity of structure, nor the contin-
uous operation of the same formative process.

Ryder ('81c, '82c, '83) has contributed a good deal to our knowledge
of the occurrence and functions of those modified forms of villi first
described by Haeckel, but I think he cannot have given their structure
very close attention or he would not have said ('83, p. 195) that "they
are apparently composed of the same tough material as that which enters
into the formation of the egg-membrane itself." He ('81e, pp. 137. 138)
regards it as probable that the egg membrane (zona radiata) is sec-rated
from the cellular walls of the follicle.

Since writing the above summary of and comments on the observations
of authors there have appeared a number of papers, some of them of con-
s lerable importance, which I was unable to utilize in forming my opin-
ions of the nature of the membranes in Lepidosteus and other fishes.

Stockman's ('83) account of the egg capsule in Salmo describes the
appearances of the pore-canals under a Reichert ^ homogeneous im-
mersion lens. In sections the limits of the pore-canals appear toothed,
owing to the presence of minute folds which have for the most part a
direction tangential to the capsule. These extend to the two ends of the
canal, and consequently its mouth appears angular rather than circular.
The substance of the capsule is beset with minute spaces which commu-
nicate with the pore-canals between the tooth-like projections, and are
believed to have a function in the transmission of nutritive material to
the egg.

Ryder ('84, pp. 3, 4, 11, Plate I. Fig. 5) states that the cod's egg is

88 BULLETIN OF THE

" covered by a vitelline membrane which is not porous or enveloped in
adhesive material. It is thin, very transparent, and laminated, as has
been stated by Sars, and at one point is perforated by a single minute
opening, the micropyle." Ryder was unable to discover the lamination
until after the action of osmic acid, and was uncertain whether it was
a natural condition or the result of the action of the acid. " The cod's
egg," he says, "is without the zona radiata found enclosing the egg
proper of the shad, whitehsh, and sculpin, and, inasmuch as it is unques-
tionably true that a micropyle perforates the zona in a number of these
cases, it does not appear that sufficient grounds exist for the declaration
that a micropyle perforates the zona radiata alone, in the face of the fact
that the vitelline membrane only is perforated in this one instance." I
have no doubt that the membrane in question possesses pore-canals, and
that it is therefore a true zona radiata. I can confirm Eigenmann's
observations in this particular, and believe that Eyder himself would
have come to the same conclusion had he observed the membrane under
the same favorable conditions.

In an extensive paper on the eggs of bony fishes Owsjannikow ('85)
describes the egg membranes of a number of the more common fresh-
water forms. The most important part of his paper deals with the cap-
sular membrane in Perca and the equivalent structure in other fishes;
but the consideration of that part will best be deferred until I come to
review the other papers which deal with that subject. I may here add,
however, that he does not recognize the existence of a villous layer
outside the zona, but regards the structure which immediately envelops
the zona in Osmerus and other fishes as the equivalent of the capsular
membrane of the perch. His description of a thin transparent mem-
brane (membrana vitellina) inside the zona radiata in Salmo trutta is
materially affected by the subsequent statement that it is not found in
other cases (Lota, e. g.), and by the admission that it may have been
an artificial product.

The pore-canals of the zona are often more deeply stained than the
substance of the matrix, and by treatment with certain reagents minute
points can be seen in the canals when highly magnified. In Lota vul-
garis the zona is very thin, and the pore-canals in patches do not pene-
trate to its inner surface. It is generally stratified, the strata being
laid down successively and all being perforated. The zona might, in his
opinion, better be called perforata than radiata. Concerning its devel-
opment in Gasterosteus the author says that the first trace of it is
seen to be a very thin membrane without any pores. These appear when

MUSEUM OF COMPARATIVE ZOOLOGY. 89

the zona has become thicker, but they are much finer than in the mature
egg. After describing the condition in Acerina vulgaris (p. 18), the
following statement is made as embodying the author's idea of what
takes place in the formation of the zona. The granulosa cells secrete a
substance (Zwischensubstanz), which surrounds the egg, one layer upon
another. The pores in this substance arise by the growth into it of the
points of the granulosa cells, or plasmatic processes from them. The
way in which the author describes the mushroom-shaped villi which
surround the micropyle in Gasterosteus shakes one's confidence in this
part of his work. It is very probable, he says, that they are derivatives
of the granulosa cells. After admitting that they have been described
in a masterly way by Kolliker, he gives an interpretation of them that
must appear to that author very remarkable. They are nothing less
than individual cells (!), each with a nucleus that is stained red in
carmine while the cell protoplasm resists for a time the action of the
dye. From the base of the cell emerges a thread which can be traced
into the zona. Very young eggs possess these appendages, as Kolliker
maintained, but they are much smaller, and consist essentially of a
nucleus which is attached by a thread and surrounded by a thin film
of protoplasm.

If everything that is stainable is to be called either nucleus or cell
protoplasm, then the current notions of what constitutes a cell will
have to be abandoned ; that will give room, it is true, for the admission
into this category not only of the villi and the yolk cells of His, but also,
I fear, of many other structures as well.

The author's views concerning the villous layer in other cases appear
from his account of Coregonus. The granulosa cells send processes into
the zona radiata. When they are removed from the immature egg, the
zona appears to be covered with small more or less pointed " Zottchen,"
which are therefore to be regarded as processes of the granulosa. Out-
side the zona radiata, Owsjannikow finds in many cases a thin viscid
layer, which he suggests is derived from the oviduct in the case of
S. trutta, but looks in Lota as though it resulted from the fusion of
endothelial [granulosa1?] cells.

Solger ('85, pp. 330-332) is evidently inclined to bring the villous
layer into connection with the presence of intracapsular corpuscles found
in the perivitelline fluid. Without committing himself unreservedly to
the views of Eimer, — that the villi are simply exuded drops of vitelline
substance, — he confirms the statement that they are not of uniform
length or shape in the case of Leuciscus rutilus, and says that Eimer

90 BULLETIN OF THE

must certainly have the credit of having especially emphasized the fact
that after a certain epoch there exists a contrivance which prevents
the further entrance of water into the intracapsular space.

I believe a comparison of the conditions in Lepidosteus with the early
account by Kolliker will convince the author that the villi have no con-
nection whatever with the interesting conditions of the perivitelline
space which he has discussed.

Ryder ('86, pp. 18, 23, 30, 35, 36, and '87) has recently noted the
existence of a zona radiata in several species of fishes, but without
having given the structure special attention. In some cases the eggs
when laid are covered with an adhesive material, the source of which
is not alluded to. In the case of Ictalurus albidus (white catfish),
there is an interesting condition of the egg membranes which he ('8G,
p. 47, and '87, p. 535) describes as follows : " The egg membrane is
double, that is, there is a thin inner membrane representing the zona
radiata, external to the latter and supported on columnar processes of
itself which rest upon the inner membrane ; there is a second one com-
posed entirely of a highly elastic adhesive substance. The columns
supporting the outer elastic layer rest on the zona and cause the outer
layer to be separated very distinctly from the inner one. . . . This pe-
culiar double egg membrane, with a well defined space between its inner
and outer layers, is highly characteristic, and bears no resemblance to
the thick, simple zona investing the egg of yElurichthys, nor has any-
thing resembling it ever been described, as far as I am aware, in the
ova of any other Teleostean." Eigenmann ('90) has attempted to show
by comparisons that the whole of this double membrane is probably a
true zona radiata, and that the columns are protoplasmic substance
which occupied the pore-canals before the separation of the two por-
tions of the zona ; but it seems to me more probable, from the " highly
elastic adhesive " condition of the substance of the outer membrane,
that it corresponds to the villous layer in other fishes. There can be
no certainty, however, as to the real homology of the outer membrane
until it has been subjected to a more careful study with especial
reference to the time and manner of its production.

Cunningham ('86) has recently rediscovered what Buchholz found out
upwards of twenty years ago about the peculiar egg membranes of
Osmerus. It is unfortunate that Cunningham overlooked the valuable
work of Buchholz. and the more surprising since he refers to Owsjanni-
kow's paper, — which I should suppose he must have consulted, — in
which Buchholz is cited. Cunningham gives figures and an account

MUSEUM OF COMPARATIVE ZOOLOGY. 91

which practically confirms that of Buchholz as to the eversion of the
outer membrane. According to Cunningham it serves as the so called
suspensory filament by which the deposited eggs are attached. He calls
the outer membrane the external zona, and agrees with Owsjannikow
that it is traversed by pores which are larger and (according to his
figure, about four times) farther apart than those of the internal zona.
He makes no mention of the outer membrane differing in any other way
from the inner, except that it is somewhat thinner.

Scharff ('87, '87") regards Beddard's zona radiata1 in Lepidosiren as
a " zonoid " layer, which he also finds present in Trigla gurnard us, where
it has a thickness of 25 /x, while the true zona is only about 8 fi thick.
" Both layers are striped, i. e. provided with minute radial pores," which
are apparently continuous through both layers. The zona is firm,
granular, and stains deeply ; the zonoid is semifluid, usually devoid of
granules, and stains only slightly. In ripe ova the latter disappears
entirely. The zona is formed before the zonoid layer. In Blennius
pholis there is no zonoid layer. Scharff " has no doubt that the egg
membranes originate from the yolk," although, as far as I can under-
stand, he advances no new arguments to prove the fact.

Henneguy ('88, p. 419) says that, notwithstanding the use of high
powers, he has been unable to find in the trout the three layers of
Owsjannikow or the denticulations described by Stockman.

A recent paper by Cunningham ('86a; deals with the interesting
question of the structure and origin of the egg membrane in Myxine
glutinosa. Even when the eggs have become 11 mm. long there is no
trace of any membrane between the yolk and the single layer of granu-
losa cells, which latter project irregularly into the surface of the former.
Sections of an egg 16 mm. in length showed that the granulosa had
become several cells deep, though not arranged in regular layers, and
that there was beneath this, and in direct contact with the yolk, a thin
homogeneous membrane.

It certainly is an interesting fact, to which Cunningham calls atten-
tion, that the epithelium is thicker at the poles than at the equator of
the elongated ovum, and that the thickness of the membrane varies
[directly] with that of the epithelium. W. Midler also observed the
same fact.

In eggs 20 mm. long the follicular cells are elongated, and form prac-
tically a single-cell layer, with the nuclei at the ends nearest the yolk.

1 Compare Beddard ('86a), and the summary of his paper given on pp. 66, 67.

92 BULLETIN OF THE

The membraue at the poles presents thickenings which are shown by
the later stages to be the beginnings of the peculiar polar filaments of
the egg membrane. These thickenings project into corresponding de-
pressions of the granulosa, the cells of which are so thinned at these
places as to be barely discernible. When the egg has increased slightly
in size (21 mm. long, 7 mm. in breadth), these thickenings affect the
external appearance of the follicle. They have the form of finger-shaped
processes covered with a single layer of granulosa cells, and project
into the connective-tissue wall of the follicle. The statement that in
the thinnest places (i. e. over the tips of the projections) the granulosa
is only .02 mm. thick, while its thickness at the exact pole of the egg is
.5 mm., is not borne out by the figure, and I therefore suppose that it is
a typographical error for .2 mm. In either event, however, the granu-
losa does not regain its normal thickness over the ends of the rapidly
growing filamentous projections of the membrane, and this fact may
have significance in determining the source of the membrane. The
author says that the membrane, if prepared in chromic acid, appears
homogeneous even when highly magnified ; but, if hardened in Perenyi's
fluid, strise perpendicular to the surface are to be seen with a high power.
The strise are not represented as rigidly straight and parallel ; they may
even branch, and are often moniliform. They have been traced to the
outer surface of the membrane, where the author believes they are con-
tinuous with fibrils of the epithelium. He is also convinced that the
membrane is homologous with the zona radiata of teleosts. I cannot
agree with him, however, in the statement, " When there are two zonas
radiatse, as in Perca fluviatilis and Osmerus eperlanus, according to Ows-
jannikow, these seem to be simply parts of one membrane differentiated
in physical properties, but essentially similar in structure."

Cunningham believes it more probable that the zona is produced by
the follicular epithelium than by the outermost layer of the yolk, and
in the following manner : " The deeper part of the elongated epithelium
cells is gradually changed into the zona radiata, the substance of the
cells being partly transformed into the substance of the membrane,
while threads of protoplasm, at more or less regular intervals, remain
unchanged, and thus give rise to the pores of the membrane."

Against this view I would urge that a metamorphosis of the epithelial
cells, especially if prolongations into the membrane occur at intervals,
would be likely to result in the closest union between the membrane
already formed and its generatrix, whereas it is exactly along this line
that the artificial separation, which the author notes in all his eggs,

MUSEUM OF COMPARATIVE ZOOLOGY. 93

takes place. Moreover, a diminished thickness in the epithelial cells
corresponding to the most rapidly increasing part of the membrane
(the filaments), not at the close of the period of their formation, but at its
beginning, is the reverse of favorable to his " hypothesis." 1 And, finally,
I would suggest that the zona is everywhere in contact with the sub-
stance of the ovum, and that the increased thickness of the membrane
at the poles may be due to the accumulation there of a greater pro-
portion of the active protoplasm than is found at the surface elsewhere.
Perhaps it might be urged against this view that the explanation would
be only partial, — that, while it might account for an increased thick-
ness of the membrane at the formative pole, it would leave the con-
dition at the opposite pole unaccounted for, and therefore could not fully
satisfy the needs of the case.

I have recently sectioned the eggs of a rather poorly preserved speci-
men of Myxine australis, with a view to getting additional light on this
question. Although the eggs had attained a considerable size, — 22 mm.
long by 6 mm. in diameter, — still there was as yet no indication of the
filamentous projections ; in fact, I could not trace a membrane continu-
ously around the egg. At the formative pole there was unquestionably a
membrane about 3.5 jx thick ; it was faintly marked like the zona radiata
of teleosts, and it presented a deep micropylar infolding, with a cellular
epithelial plug. Nevertheless this membrane gradually grew thinner
in passing from the formative pole, until it could no longer be recognized.
It had about the same extent as the protoplasmic cap. At this stage
there was no more accumulation of protoplasm at the opposite pole
than at the sides of the egg ; but there also was no more evidence of a
zona radiata at this pole than at the sides of the egg. That is all I
cau offer at present in reply to the possible objection which I have
suggested. If it could be shown that the zona is developed at the
nutritive pole of the egg without the presence of an accumulation of
protoplasm there, and that the granulosa is more highly developed there
than on the sides of the egg, I should admit that a strong case would be
made against the view I defend.

1 It is true the author has offerer! an explanation of this; viz. that the filaments
are formed from the cells at the sides of the process, where the epithelium is very-
thick, and that they are pushed up by the growth at the base. But I should
imagine it would be difficult to explain how secretions from lateral cells could do
anything more than increase the diameter of the process.

94 BULLETIN OF THE

2. Capsular Membrane.

As I have already pointed out, the capsular membrane, since it was
first described by Miiller in the perch under the erroneous supposition
that it was the same as the zona radiata of the salmon, has often been
confounded with that membrane. In looking over the literature on the
egg membranes of fishes, after I had worked out the structure of the
villous layer in Lepidosteus, I was forcibly impressed by the resemblance
of that layer to the descriptions that had been given of the outer mem-
brane in the perch, and at first thought they might be homologous
structures. It was particularly the account given by Ransom ('68,
p. 455, Plate XVI. Figs. 30, 31) of the root-like prolongations of the
tubules in the capsular membrane which suggested comparison. It
therefore seemed necessary to examine carefully all that had been
written on the egg capsule of the perch. The result has not confirmed
my first supposition.

Muller ('54) himself gave an excellent account of the structure of
the capsule, and accurately formulated the most interesting question
concerning its morphological significance. He described the egg enve-
lope (capsular membrane) as about 0.11 mm. thick; its outer surface
as covered with six-sided facets, which average 19/t in diameter. Each
facet contained in its centre an open funnel, which was continued* into
a vertical tubule as long as the thickness of the capsule, and from 2.2 fx.
to 4.7 fx in diameter. In fineness these were comparable to dentinal
tubules. They terminated on the inner surface of the capsule in fun-
nel-shaped enlargements, just as they did on the outer surface. Upon
eggs that had been boiled or hardened in chromic acid, it was possible
to see that the tubules had a spiral course, but they also appeared
narrower (1.1 fx.) than in the fresh state. The tubules were filled with
a thickish (albuminous?) mass, which in the fresh egg was clear, without
deposits, and under pressure projected from the funnel like a rounded
stopper or cylinder, but appeared to be coagulated by boiling and treat-
ment with chromic acid. When one compressed the fresh egg to burst-
ing, the oily substance of the yolk might be pressed into and through
the tubules ; thus was effected a delicate injection which might greatly
distend them. Between the tubules, however, there was nothing pressed
out, which proved that on its deeper surface between the tubules the
capsule was closed. In the inter-tubular portions of the membrane,
after the eggs are hardened, there were to be recognized, besides a
gelatinous nearly invisible material, exceedingly delicate projections or

MUSEUM OF COMPARATIVE ZOOLOGY. 95

filaments placed alternately and running across between adjacent tu-
bules. These were thickest next to the tubule, and rapidly tapered to
very fine threads. In his opinion, the method of the furmatiou of the
tubules might be made out during the winter. " The question is, whether
each of the tubes arises from a single cell, which becomes open, or whether
the tubes are originally inter-cellular, and whether their walls result from
the remnants of several cells in contact with each other."

A similar condition is maintained by Miiller for Acerina vulgaris, but
the membrane in this case was much thinner and the tubules conse-
quently shorter.

Lereboullet ('54, pp. 242, 246) also discovered independently, per-
haps even before Muller,1 that there were in the perch what he called
hollow closely interlaced piliform appendages (also called stiff curved
filaments), which traversed the whole thickness of the shell, and to which
he attributed the agglutination of the eggs into a network. He also saw
besides these the much finer pore-canals.

In regard to the chemical nature of the capsular membrane, it was
maintained by Von Baer ('35) and by Leuckart ('55, p. 260) that it
was an albuminoid substance. Kolliker ('58) called it gelatinous, but
His ('73, p. 15) proved that it at least closely resembled chondrin, and
consequently claimed the right to call it a cartilage capsule.

Reichert ('56, p. 93) was not able to add much to Midler's account of
the structure of the capsular membrane. Concerning its origin he was
at first inclined to believe that it resulted from [a metamorphosis of?]
cells (" aus Zellen hervorgegangen "), and theiefore to regard it as a pro-
duct of the membrana granulosa. This conclusion was strengthened by
finding the granulosa composed of cylindrical cells in the case of Esox,
and that when this membrane appeared in the perch the granulosa cells
had disappeared ; but subsequently, finding that the follicular cells in
the perch were round, and not finding any transitional stages from the
epithelium to the membrane, he was compelled to leave the question
unsettled. Reichert was certainly looking in the right direction, and
evidently very near to a fair settlement of the question.

It remained for Kolliker ('58, p. 90) to confirm this supposition of
Reichert. He found that in February the capsular membrane had a
thickness of 45 /a to 75 //,. The tubules, he says, are formed by the
outgrowth of the epithelial cells of the follicle, so that the jelly which
joins them can only be a substance secreted by these cells. These so called
tubules were after all not hollow structures (" noch keine deutlichen

1 See Kolliker ('58), p. 81, foot-note.

96 BULLETIN OF THE

Hohlgebilde "), but apparently solid pale processes of the epithelial cells,
on which the anastomosing filaments found by Miiller were visible,
Kolliker did not doubt, however, that they were from the beginning
hollow cell processes, but they still contained at the time of their forma-
tion cell contents, and only subsequently became clear. Their indepen-
dent nature was shown by the fact that in chromic preparations they
could be drawn out from the jelly without losing their union with the
[rest of the] epithelial cells. As long as the eggs remained in the fol-
licle the epithelial cells probably continued in union with the tubules;
but at the liberation of the eggs the cell bodies probably fell off, with
the exception of the walls, which were continuous with the tubules, and
then constituted the hexagonal facets of Miiller. Kolliker was able to
produce a similar effect by artificially separating the cells from the
capsule.

Ransom ('68, p. 455, Plate XVI.), who does not seem to have been
acquainted with the papers of either Reichert or Kolliker, compares the
capsular membrane in consistence with fresh fibrine. "The striae look
like tubes, have a distinct double contour for each wall (Fig. 28), but are
filled with a vacuolating material, and do not seem to convey anything
into or out of the egg." The outer surface was thrown into folds which
radiated from the ends of the "tubes," but the hexagonal markings seen
by Miiller could not be made out. The tubes, instead of being funnel-
shaped, at their inner terminations divided into root-like processes, and
were in some way intimately adherent to the outside of the dotted yolk-
sac (zona). The clear matrix was elastic and concentrically laminated.
" The appearance described by Miiller, of oil granules passing through
the tubes, may possibly have been due to vacuolation in them." Experi-
ments with colored fluids to ascertain if there were any absorption of
fluids along the "tubes" always gave negative results: the cleavage
went on, the yolk-sac was dyed throughout, the clear matrix more than
the tubes, the germinal mass not at all. Either, therefore, the tubes
did not subserve imbibition at all, he contends, or in a much smaller
degree than the clear matrix.

Waldeyer's ('70, p. 81) conclusion about the origin of the zona from
the granulosa appears to me to have resulted, in part at least, from the
fact that he was unable to discover any essential difference between it
and the capsular membrane of the perch. He says the latter does not
differ from the former in the principle of its structure. He rightly adds,
that "here [capsule] it is to be seen with the greatest distinctness that
the filaments are connected with the subsequently somewhat degenerated

MUSEUM OF COMPARATIVE ZOOLOGY. 97

remnants of the follicular cells." He further adds, that occasionally
it appeared as though there were between these two membranes a thin
flat expanse of granular protoplasm in which the filaments terminated.

His (73, pp. 14, 15), who examined perch eggs in April, also confirms
the opinion of Kolliker, and gives a figure to show the relation of the
radial processes to follicle cells. The radial streaks consist, he says, of
a turbid substance, which stains in osmic acid, and is continuous with
conical nucleated bodies which form a continuous layer between the fol-
licle wall and the outer surface of the capsule. Kolliker is therefore
right in considering the layer as "granulosa," and the capsule as its
product.

Brock ('78, p. 556) gives the following clear, and I believe correct,
account of the capsular membrane of the perch. The follicular cells,
which at first are in close contact with the young egg, are raised up from
the zona radiata by the developing gelatinous layer, and with the advan-
cing growth of that layer are drawn out on the side toward the egg into
long processes which can be followed up to the zona. In older eggs
these follicular cells, separated by considerable intervals, (an indication
that their multiplication soon stops,) lie in shallow depressions of the
gelatinous capsule, and with their lower pointed ends continuous with
the processes. These appear to end at the zona with conical enlarge-
ments, but the author will not affirm that this is a constant feature.
Brock also maintains that Serranus hepatus has a very similar gelatinous
capsule. The follicular cells, however, are very peculiar. They form a
network of thin flat cells, which are in contact with each other only by
means of lateral processes, while perpendicular processes, which are
sometimes branched and exceedingly fine, can be traced through the
jelly to the zona radiata. Concerning the development of the capsule,
nothing is known.

So far as regards the capsular membrane of the perch, Hoffmann ('81,
pp. 19, 20, 27-29) comes to totally different conclusions from Brock, and
expresses views which seem to me untenable. In October, ovarian eggs
from 600 to 700 /x in diameter possess a membrane 5 /x thick, which is
composed of two layers of nearly equal thickness. "The inner is the
true zona radiata ; the outer is composed of very numerous, small knob-
like projections, which stand very close together and correspond exactly
to the villi of the cyprinoids. On the free surface of the conical villi lie
the granulosa cells."

It cannot be denied that the figure cited (I. c, Taf. I. Fig. 9) corrob-
orates the description given. But there is one fact which I should im-

VOL. XIX. — NO. 1. 7

98 BULLETIN OF THE

agine would have caused the author more concern than it seems to have
done. If his drawing accurately reproduces the conditions, there must
have been about four times as many villi as there were granulosa cells.
That in itself alone might not be of any significance to the author, espe-
cially as he disclaims any genetic connection between the granulosa and
the underlying capsular membrane, but it does seem as though it should
have received some explanation in view of the ultimate relation (Taf. I.
Fig. 10) which Hoffmann admits to exist between the radial fibres of the
capsular membrane and the cells of the granulosa. This is what he says
about the later (February) stage of the egg : The zona itself is seen
to consist of two layers, the inner much thicker than the outer. From
the latter there arise with small triangular bases long peculiar fibres
only 1 jx in thickness, which are stained in osmic acid precisely like the
outer layer of the zona from which they arise. The outer ends of these
fibres are thickened, even more than their inner ends, and form a con-
tinuous laver, between which and the zona radiata the fibres themselves
are stretched like so many columns. " Over the proximal 1 ends of these
fibres the granulosa cells are arranged in srich a way that a granulosa cell
fits into each thickened end (Taf. I. Fig. 10)."

If after the [ovarian] eggs have lain in water a short time they are
transferred to osmic acid, it becomes very easy, says Hoffmann, to iso-
late both this layer (formed by the expanded ends of the fibres) and the
granulosa in the form of large shreds (" Lappen "). From such prepa-
rations one can readily convince himself, he says, that the expanded
ends of the fibres form a continuous sheet, and are not processes of the
granulosa cells, as one is at first inclined to assume, and that the fibres
are, as the examination of the early stages proves, only the greatly gr own-
out conical villi.

That which seems to me to need explanation is, Why is the numeri-
cal relation between the villi and the granulosa cells so different at dif-
ferent stages in the growth of the egg, and why does this relation become
such an invariable one in the later stages of development 1

It might be answered, in reply to the first question, that the granu-
losa cells undergo rapid multiplication, and that cell division occur-
ring twice for all granulosa cells between October and February would
explain the altered relations ; but is it not more reasonable to suppose
that, through some unexplainable accident, Hoffmann has been led to
attribute eggs to a perch which were taken in October from some other

1 It is not clear to me in what sense tlie author can use the word "proximal " of
the ends of the fibres which are directed aica/j from the centre of the egg.

MUSEUM OF COMPARATIVE ZOOLOGY. 99

fish possessing a villous layer, than to ignore the evident constancy be-
tween villi and granulosa cells, and to assume an extensive multipli-
cation of the latter in eggs during the period of their growth from a
diameter of .7 mm. to .75 mm.?

The latest paper dealing with the capsular membrane of Perca is that
of Owsjannikow ('85, pp. 3-8), who reaffirms Midler's claim that the
" tubules " are hollow structures, and corroborates Ransom's discovery
that their inner ends are divided into branches which penetrate the
pore-canals of the zona radiata.

On gold or silver preparations of ovarian eggs, one finds the granu-
losa cells * bounded by broad lines of a precipitate, so that there must
be present a large amount of intercellular substance. The cells them-
selves lie, as previous authors have shown, over the beginnings of the
corkscrew-shaped canals. These "beginnings." in the fully developed
egg, are not at all cells, and have no nuclei ; they are little funnels, with
the narrow end sunk as it were into the jelly. The finely granular
substance lies more compactly in the bottoms of the funnels ; it is
scantier on the margin, and in many places extends beyond the rim,
of the funnel. This tissue (granulosa cells) often presents the appear-
ance of stellate cells joined together by numerous processes, and sepa-
rated from one another by abundant intercellular substance. The
more closely packed molecules at the bottom of the funnel had given
occasion, he says, to the assumption that there was a nucleus there

1 In his account of the Graafian follicle, not always readily harmonized with his
figures, and sometimes obscure, he claims the presence of a greater number of epi-
thelial (or endothelial, for he recognizes no difference between the two) cell layers
than have usually been admitted. Thus, if I rightly understand the explanation
of Fig. 4, Taf. I., there are in Perca, e. g., two epithelial cell layers between the
vascular layer and the capsular membrane, — an outer layer of flat endothelium and
a deeper layer of cylindrical granulosa cells; but in the text (pp. 4-8) he speaks of
only two cell layers, an inner and an outer granulosa (!), which are separated by
the vascular layer. From his description of the latter as the source of the new
eggs, there can be no doubt that it is the " germinal epithelium " of authors. I
can reconcile this apparent contradiction between text and figures only on the
assumption that Figure 4 and its explanation belong to a period in Owsjannikow's
studies when he was not as yet convinced of the error of taking " the granular accu-
mulation in the bottom of the funnels of the 'tortuous canals ' for a cell nucleus."
That he ultimately supposed that to be an error appears from his description, and
the statement (p. 5), " Die am Grunde des Kelches dichter an einander gelagerten
Moleceln gaben die Veranlassung dort einen Kern anzunehmen."

In the case of Osmerus, moreover, he recognizes the existence of two layers of
large flat endothelial cells in addition to the granulosa. (Compare his explanation
of Fig. 8, Taf. I.)

100 BULLETIN OF THE

From the bottom of the funnel there proceeds to the zona radiata a
strongly and evenly twisted canal, which breaks off easily at the bottom
of the funnel. Owsjannikow cannot agree with Kolliker, who maintained
that in February these were solid fibres, because already in Novem-
ber and December he finds them hollow. The superficial layer of
the gelatinous mass, as well as that part which immediately surrounds
the canals, appears to be more compact than the rest of it, and the
vicinage of the funnel is more deeply stained by aniline red or gold
chloride than the other parts. The granules which occupy the canals
or the funnels never enter into the gelatinous substance when the canals
are ruptured, but escape into spaces which surround the canals. The
inner end of the canal does not terminate in a pointed maimer, as
figured by His, but is often enlarged into a funnel, and sometimes
divided into two or three fibres, — in one case into so many that
it looked like a brush. On one occasion these branches were traced
through the zona. These processes are to be seen only in stained speci-
mens (gold chloride followed by aniline blue), because, having the same
refractive power as the substance of the zona, they are otherwise undis-
tinguishable. The fine molecules which lie on the inner surface of the
zona were found to be deeply stained, and the author concludes that the
dye must have penetrated through the spiral canals. The function of
these canals must consist in the transportation of nutritive material to
the yolk. They arise out of the granulosa cells, are similar to those
seen by Eimer in the adder, and are not processes of the zona radiata, as
affirmed by Hoffmann. The lateral processes from the canals were also
seen by Owsjannikow, but he has for them another interpretation. The
matrix (Zwischensubstanz) appears to lie in layers parallel to the surface.
Upon its being swollen by any fluid, narrow fissures are formed be-
tween these layers, which join the canals and appear as processes from
them.

Besides the difficulty of trying to comprehend how fissures could
arise as a result of the swelling of a gelatinous mass, — it would seem
that the reverse process ought to be more favorable to their appearance,
■ — the sufficient answer to this last claim is, that the transverse processes
are more deeply stained than the remaining portions of the matrix,
which could hardly be the case if they were simply fissures.

It was in the hope of ascertaining something more about the inter-
esting capsular membrane in the perch, that I advised Mr. Eigen-
mann ('90) to include that fish in his studies on the development of

MUSEUM OF COMPARATIVE ZOOLOGY. 101

the micropyle. I believe it will be seen from his results that there is
still very good reason for maintaining that the tubular or columnar
structures of the capsular membrane, which have been the objects of
so much study, are derived from the granulosa cells, one from each cell,
and that the process by which the capsular membrane is formed is
neither simply a cell secretion nor exclusively a cell metamorphosis.
Although Eigenmann has not succeeded in getting stages which show
clearly all the steps in the formation of the capsule in Perca, he has
shown that there exist conditions in the later stages of the development
of the egg in Esox (Eigenmann, '90, Plate III. Fig. 37) which seem to
me of considerable importance in interpreting the conditions in Perca.
In Esox the cells become elongated, and the central (axial) portion
retains the granular and stainable properties of unmodified cell proto-
plasm. This axial portion is not cylindrical, but conical ; its base is
directed outward and contains the nucleus. The peripheral portion
— which is more and more abundant as one approaches the zona —
is more homogeneous than the axial part, and reacts with dyes in a
different way. The cell boundaries have been previously lost. The
boundary between these two constituents of the cell is not at first
sharp, so that this phase of the process may perhaps be regarded as
one of metamorphosis rather than of secretion.

I believe that Perca must pass through some such stage as this during
the earlier part of the process which produces the capsular membrane.
I imagine that the distinction between the axial and the peripheral por-
tions of the cell becomes more and more sharply defined as the thicken-
ing of the capsule goes on. Meanwhile the axial portion does not long
retain the indifferent condition, but is metamorphosed, especially at its
periphery, into a highly refracting substance, so that there is reason for
regarding the structure as tubular. This metamorphosis advances till it
has practically obliterated the cell, even though a nucleus with a small
amount of enveloping protoplasm may still be made out at its distal
end in very late stages of ovarian growth. At any time before this, and
after the distinction between a funnel part and a tubular part has arisen,
the less modified distal portion of the cell may doubtless be easily sepa-
rated from the secreted gelatinous substance and also from the meta-
morphosed cell process. Such at least is the view which I have formed,
after a comparison of the granulosa in Perca and in Esox.

It would certainly be remarkable if the perch were the only represent-
ative of bony fishes in which such a process took place. I believe that
there are a few cases already known which may prove upon renewed

102 BULLETIN OF THE

inquiry to be essentially the same as the perch. The similarity to the
perch shown by Acerina vulgaris was recognized by Miiller ('54, p. 189).
"In Acerina," he states, "the egg membrane has the same structure [as
in Perca], only it is much thinner, and consequently the tubules are only
short, not longer than the breadth of the areas." Eansom ('68, pp. 453,
454) also says of this species that its "yelk-sac has an outer layer or
' Eikapsel.' " But he adds, that " the outer layer appears to be contin-
uous with, and similar in structure to, the yelk-sac proper." However,
Owsjannikow ('85, pp. 17, 18, Taf. I. Fig. 13) has given an account of
it which points still more strongly to the resemblance claimed by Miiller.
That part of his account is especially significant in which he states that
in some preparations the follicle cells have the form of very narrow
cylindrical epithelium ; the broad end of the cell is directed outward,
the pointed end inward toward the zona. The cells, he adds, lie in a
transparent non-staining layer, similar to that in which the spiral canals
(in the perch) are located. Finally, a third condition is described in
which the cell form is lost. The structure begins with a broad short
funnel, and passes at once into a narrow, straight hollow fibre which
imbeds itself in the zona radiata.

The peculiar follicular layer described by Scharff ('88, p. 69, Plate V.
Fig. 15) in the interesting egg of the shanny (Blennius pholis) also
appears to have begun to undergo a modification in the same direction
that leads in the perch to the formation of a capsular membrane. The
substance which Scharff calls " interstitial " is, I believe, morphologically
the same as the gelatinous secretion of the follicular cells in Perca.

3. Micropyle and Micropylar Plug.

Since Doyere ('50) discovered, in 1850, an aperture leading through
the membrane of the egg of Syngnathus, and gave to it the name of micro -
pvle, there has been a good deal of attention given to that structure.

Independently of each other, and probably without knowledge of
Doyere's discovery, Eansom ('5G) in England and Bruch f55tt) in Ger-
many rediscovered, in 1854, this structure in fish eggs, and both applied
the name which had meantime become current through Midler's ('51 and
'54b) discovery of a similar canal in the egg membrane of Holothuria, to
which he also gave the name of micropyle, borrowed from the usage of
botanists.

Ransom in fact succeeded in observing in the egg of the stickleback
the passage of spermatozoa through this opening ; Bruch was less fortu-
nate with Salmo fario and S. salar, although he made special effort to

MUSEUM OF COMPAKATIVE ZOOLOGY. 103

discover if such a passage took place, and particularly emphasized the
fact that the orifice of the micropyle is of exactly the same size as the
spermatozoon.

These discoveries were soon (1855) confirmed by Leuckart ('55,
pp. 257-264) and Reichert ('56, pp. 83, 84, 98-104, Taf. IV. Figs. 1-4)
on the Continent, and by Thomson ('59, p. [100]-[104]) in England.
Their observations established the fact of the existence of the micropyle
in numerous fishes, and under several modifications of form. Ransom
had given a fairly accurate account of the structure of the micropylar
region, but Reichert especially insisted upon the differences between an
invaginated portion of the membrane and a passage through the latter
in the case of cyprinoids. He distinguished three regions, — an ap-
proach (Eingang), a fundus, and a neck or cylindrical canal, the length
of which was diminished from what it would otherwise have been by a
reduction in the thickness of the membrane to one third its normal
dimension.

It was, however, the interest in fertilization stimulated by Newport's
researches on the impregnation of the ovum in Amphibia, and by Keber's
paper, "De introitu spermatozoorum in ovula," etc., Konigsberg, 1853,
that gave paramount importance to these discoveries, and attracted
general attention to them.

Perhaps it is not surprising, in view of this fact, that the ovarian
egg was less studied, and that the relation of the micropyle to the gran-
ulosa cells in its vicinity was not especially examined ; and yet those
observers who concerned themselves with the questions relating to the
origin of the different egg envelopes must have been very near to inquir-
ing what share the granulosa had in producing so remarkable a modifi-
cation in the egg membranes. Kolliker ('58, p. 92), although only
incidentally making observations on the micropyle, established the fact
of its existence in a large number of cases. He regarded it simply as an
enlarged radial pore of the secondary vitelline membrane (zona), which
might be produced, he thought, by a process of resorption.

Several subsequent writers have concerned themselves only with ques-
tions relating to the form and position of the micropyle, and its probable
function. Thus Buchholz ('63, p. 72) compared the micropyle in Os-
merus eperlanus to a crater the floor of which is closed except for a mi-
nute canal in the middle of it, which traverses the thickness of the wall ;
Ransom ('68), besides adding some unimportant details to his earlier
description of Gasterosteus, described briefly the micropyle in a large
number of other (fresh-water) fishes, claiming that it always terminated

104 BULLETIN OF THE

in a small elevation lying directly over the germ, and concluded, as the
result of experiments (pp. 459-462) made on Gasterosteus pungitius,
that " the function of the micropyle is to admit the spermatozoids to the
surface of the yolk " ; and His ('73, pp. 3, 4) described with some detail
the structure of the micropyle in Salmo salar and S. fario, in both of
which he recognized a shallow depression (" Mulde ") surrounding the
crater, which in S. fario terminated in a deep funnel, and this in the
canal. He also showed that ouly one spermatozoon at a time can pass
the micropylar canal, which terminates somewhat eccentrically over the
germinal disk.

Hoffmann ('81, pp. 33-36) has confirmed for a large number of fishes
the observations that the inner end of the micropyle terminates in a
papillary elevation of the zona radiata, and that in the ovarian egg it
lies directly over the germ. From a comparison of the dimensions of
the spermatozoa and the calibre of the canal, he also draws the conclu-
sion that not more than one spermatozoon can traverse the micropyle
at a time. In nearly all the micropyles figured by Hoffmann the canal
is a tubular passage without any special enlargement ; but in the case
of the herring's egg — which is the one most carefully described — the
outer half of the passage is enlarged into a conspicuous bulbous cavity
(Taf. I. Fig. 19), which, so far as I recall, has been seen in only one
other instance, that of Petromyzon as figured by Calberla. But the
greatest interest attaches to the conditions figured for Leuciscus rutilus
(Taf. I. Fig. 20). In this case there exists a distinct plug of granulosa
cells occupying the depression in the egg membrane at the micropylar
region. Since the author does not mention the fact in the text, it is
probable that he attached to it no importance. I think, hcwever, it is
the first clear proof published of the existence of a specialization in the
granulosa of the micropylar region in any teleost. On account of the
rather diagrammatic rendering of the granulosa cells, it is not possible
to be very confident about the existence of a specialized micropylar cell,
but the fact that a single cell forms the apex of the plug favors that
view, and I shall be surprised if such a structure is not hereafter demon-
strated in this European fish.

Of the more recent writers on the micropyle, Owsjannikow ('85,
pp. 11-13, Taf. I. Figs. 5-7) describes for Osmerus eperlanus a micro-
pylar apparatus composed of two portions, an external and an in-
ternal, corresponding respectively to the two membranes which envelop
the egg, — the " external zona radiata" (which corresponds, in his
opinion, to the outer [capsular] layer in Perca) and the " internal zona

MUSEUM OF COMPARATIVE ZOOLOGY. 105

radiata." The apparatus has the form of a crater-like depression, about
as described by Buchholz and Ransom. Where the membranes take the
direction of the crater, they form folds with the pointed ends directed
inward. But of more interest are his statements, that the zona radiata
externa takes the greater share in the formation of the crater, and that
"other tissues, especially the endothelium and granulosa cells, participate in
the same." Owsjannikow was thus, I believe, the first person after W.
Miiller ('75) to call attention to an intimate relation between granulosa
and micropyle.1 But there are some elements of uncertainty about his
descriptions and figures that seem to baffle every attempt to reduce
them to harmony. The most perplexing thing about his description is
the use of the term " endothelium," which is at first used for Osmerus
in the following connection (p. 10): "Die Graafschen Follikel der
Osmeruseier bestehen aus Endothel, Gefassen, Bindegewebe und Folli-
kelzellen." In the description of other eggs (Perca) the word " Endo-
thel " is also used as though applied to cells which lie outside the
vascular layer, and even as though including the germinal epithelium
of other authors (p. 4). Unless an endothelium having a very different
position from that previously described by him is meant, when he
says that it participates (as well as the granulosa) in the micropylar
structure, I believe that the author has fallen into some error ; for I
am of opinion that neither the connective-tissue layer with its blood-
vessels nor the germinal epithelium shares directly in the formation of
the micropylar apparatus. Neither do I believe that there exists inside
the connective tissue any layer of cells except the granulosa. Moreover,
I do not think that any layer of endothelium, either inside or outside
the vascular layer, has been figured as sharing in the formation of the
micropyle. It does not help matters in the least to add that the author
discountenances (p. 4) any attempt to draw a distinction between epi-
thelium and endothelium ; for after saying that " Endothel und Granu-
losazellen " share in this formation, he proceeds with a description
which certainly allows the assumption that there is only a single layer
of cells involved, to which, however, he gives successively the names of
granulosa, endothelium, and epithelium.

1 Although published several years ago, Owsjannikow's studies were not made
until some time after I had demonstrated tlie conditions in Lepidosteus which have
been described above. His paper, as well as the more recent one of Cunningham,
has therefore had no influence in determining the course or the results of my studies
on Lepidosteus, nor did it influence me to suggest a comparative study on the eggs
of bony fishes, such as Mr. Eigenmann has undertaken ; for I had already proposed
that question to one of my students before either paper was published.

106 BULLETIN OF THE

On " teased " preparations Owsjannikow often finds the zona deprived
of its cellular covering, but ordinarily the detached cells are to be found
in the form of a continuous membrane, on which a conical projection is
to be seen. The form of the projection corresponds exactly to that of
the external micropyle ; it is hollow ; the cells at the entrance to the
micropyle have the form of a crown, and become smaller and smaller
toward the bottom of the crater. I am not sure that I fully understand
the figure (Taf. I. Fig. 6) which the author refers to in this connection,
but it appears to me to be a view of an egg from the animal pole ; the
granulosa cells of the crater, having been detached, are seen partly in
side view, but somewhat obliquely, as a conical structure, and the pore-
canals of the external zona of the crater are visible where the granulosa
cells have been lifted. In the middle of the figure is an optical section
of that portion of the zona which forms the internal projection, and in its
centre the micropylar canal. There is apparently a single layer of cells,
and this I take to be the granulosa. It is to be regretted that the
author has not furnished us with a strictly radial section through the
micropyle and the accompanying structures on a sufficiently large scale
to enable one to determine what becomes of the membrana propria of
the theca folliculi in the region of the micropyle. One would infer, from
the statement that this granulosa cone was hollow, that the theca must
follow the course of the crater ; but if it does, it must be different from
all other known cases. Not even in Perca does the membrana propria
suffer any deflection or infolding due to the participation of the gran-
ulosa cells in the formation of a micropylar structure. I have also been
considerably perplexed by Owsjannikow's Figure 5 (Taf. I.). At first I
took it to represent a strictly diametric section of the egg and its mem-
branes. With that understanding of it, I imagined that the large oval
body just above the micropyle might possibly represent a single micro-
pylar cell in some way loosened from its natural position ; but more
careful study leads me to believe that this is a figure representing in
part an optical section, in part a surface view, and that the oval struc-
ture presents an oblique view of the external entrance to the funnel-
shaped cavity of the crater, still lined with granulosa cells, while all the
rest of the figure represents a view of the egg as it would be seen in
optical section. Owsjannikow states that the inner micropyle can be
regarded as a somewhat enlarged canal of the zona, and claims that it
subserves the nutrition and growth of the egg ; for he has traced from
the inner end of the canal a row of granular bodies which were con-
tinued in the yolk as a fine thread, which at last disappeared. This row

MUSEUM OF COMPARATIVE ZOOLOGY. 107

of granules and its thread-like continuation the author regards as a pro-
duct of the granulosa cells. But at present there are no data, he says,
either teleological or phylogenetic, which can explain the remarkable
structure of the external micropyle.

Ryder ('86, p. 30, Plate VI 1. Fig. 35), who has demonstrated the
existence of the micropyle in the eggs of several fishes, speaks of the
passage through the capsular membrane in Perca Americana as "a
wider pore-canal which leads to the micropyle." It is evident from
Eigenmann's ('90) account and from his figures that this statement is
inaccurate.

Cunningham ('86*, pp. 59, 61-63, etc., Figs. 2-4, 12) has shown much
more satisfactorily than W. Midler ('75) did, that in Myxine giutinosa
the follicular epithelium plays an important part in the formation of the
micropyle. Of an egg 16 mm. in length he says : " At the exact pole of
the egg there is a differentiated portion of epithelium, where a prolife-
ration of the latter has taken place. This portion is composed of poly-
gonal cells, which are little or not at all elongated, and towards the egg
it runs out into a thin cylindrical process which penetrates the next layer
[zona radiata] as shown at e. p. [Fig. 2]. . . . This process penetrates
the vitelline membrane [zona radiata], occupying a tubular cavity in the
latter, and passing through it to form a hemispherical projection on its in-
ner surface. . . . This cellular projection is covered by a thin membrane
continuous with the vitelline membrane, and is not in immediate con-
tact with the germinal disk. . . . There is thus at one pole of the nearly
ripe ovum a tubular canal extending through the chorion [zona radiata],
but not open internally, filled up by a cylinder of cells projecting from
the follicular epithelium. ... It is evident," the author adds, " that this
aperture is to form the micropyle in the ripe ovum. ... It is probable
that careful investigation would show that in all Teleosteans whose ova
possess a micropyle that structure is produced by a projection of cells
from the follicular epithejium." Cunningham also believes it " at least
possible that in all vertebrates the micropyle will be found on investiga-
tion to be produced in the same way as in Myxine, namely, by the
growth of a cellular process from the follicular epithelium towards the
vitellus while the vitelline membrane is beino; formed."

In an egg 20 mm. in length " the proliferation and differentiation of
cells at the pole in the follicular epithelium have disappeared, but the
cylinder of cells, though reduced in size, still remains in the micropyle,
and is evidently destined to keep the latter open until the maturation
of the ovum is complete." This egg was from material obtained in

108 BULLETIN OF THE

December. Older eggs, obtained at the end of January, although only
slightly larger than the December egg (21 mm. long), presented a very
different appearance at the micropylar region. Cunningham says of the
latter : " The micropyle is somewhat narrower, and the cells present in
it at previous stages have disappeared almost completely, only a little
debris remaining. The micropyle seemed also in these ova to be open
internally, though of this point I am not absolutely certain. If there
is a membrane closing the inner end, it is an extremely thin one."

Cunningham has shown conclusively, I believe, that the granulosa
has much to do with the modifications of the egg membrane in the
micropylar region, but there are several particulars concerning which
his description and figures leave me in a rather unsettled state of mind.
In the first place, the author does not seem to distinguish with sufficient
sharpness between a funnel-like region, which may be partly the re-
sult of an infolding of the membrane, and a passage through the mem-
brane, which I have called the micropylar canal. It seems to me possible
that his uncertainty as to whether the micropyle is closed at its inner
end at a late stage may be due to this fact. The disproportion between
the calibre of the " micropyle " and the size of the spermatozoa1 is not
alluded to, but at once suggests to me that the structure in question
may be the equivalent of the micropylar funnel only. I should be quite
certain that it was so, were it not that the drawing of the latest stage
(Fig. 12) — which is not sufficiently explained — admitted two inter-
pretations. In this figure the whole passage is divided into two por-
tions of about equal length, but of very unlike calibre. The inner half
is a narrow canal with parallel walls, about one third of a millimeter in
diameter (actual size about 10 /a) ; the outer half is abruptly widened
to 6 or 8 mm. in diameter, and gradually increases toward the gran-
ulosa to 10 mm. (nearly 300 //, actual size). There are no granulosa
cells, however, in either portion of the passage. The almost flat-bot-
tomed outer half of the passage would appear to be the equivalent of
the micropylar funnel in bony fishes, and I should certainly have so
regarded it if Cunningham had not evidently considered the inner nar-
rower portion as a part of the " micropyle " of previous stages from
which the cells had disappeared, leaving " only a little debris." If the
author is right in this assumption, that the narrow part of the ap-

1 In its narrowest place the " micropyle " of the author's Figure 3 is represented
as 5 mm. in diameter in the drawing, which, being magnified 280 diameters, makes
its actual diameter about 18 /x, whereas the actual diameter of the head of a sper-
matozoon (Fig. 14) is not over 7 yu.

MUSEUM OF COMPARATIVE ZOOLOGY. 109

paratus was once occupied by granulosa cells, then either the true
micropylar canal has not been seen in Myxine, or it is formed in a
different manner from that of bony fishes, for in no case is it occupied
in the latter by a plug of cells from the follicular epithelium. The
former alternative is, in my opinion, the more probable. This con-
clusion I base partly on the appearance of Cunningham's Figure 3, and
partly on the conditions presented by sections of an ovarian ovum of
Myxine australis, which I have studied since reading Cunningham's
paper. In his Figure 3, the plug of granulosa cells which is sunk
into the yolk is completely enveloped in a uniform layer not more than
2 fx thick, which not only separates its deep end from the yolk, but
also its sides from the membrane called by him vitelline membrane, or
zona radiata. What the significance of the part of this thin mem-
brane lining the chimney-like elevation of the zona radiata may be, I
cannot say, unless it is reflected at the upper edge of the chimney to
form the outermost layer of the zona ; but the portion which separates
the yolk from the granulosa plug I regard as the equivalent of the first
formed portion of the zona radiata, and believe that the true micropylar
canal will be found in the form of a minute passage through that mem-
brane. My principal reason for this opinion rests on the condition of
this region in the egg of M. australis. This egg was about 22 mm.
long and 6 mm. in diameter. It was enveloped by a follicular epithelium
composed at the animal pole of a single layer of cells, averaging about
10 \x. thick. Over the region of the flattened germinative vesicle the
granulosa was gradually thickened to about 25 p, and from the middle
of the thickening a solid plug of cells about 35 ju. long and 25 p in di-
ameter projected into the yolk. The membrana propria of the follicular
theca passed over the micropylar region without being at all infolded, so
that the total thickness of the granulosa, measured from the apex of
the plug, was about 60 /x. The cells of the plug were not well pre-
served, but appeared to be of about the same relative size as in Cun-
ningham's Figure 3, — i. e. of one half or one third the diameter of the
plug. There was no enlargement at the apex of the plug as seen in
his figure. Between the granulosa and the yolk, and in contact with
both, was a highly refractive thin (3.5 /u.) membrane, which at first
appeared homogeneous, but in which I believe I have detected at
intervals radial markings. This membrane became thinner at some
distance from the pole.

The whole apparatus had such a striking resemblance to the micropy-
lar apparatus in Lepidosteus that I cannot doubt that the granulosa

HO BULLETIN OF THE

plug represents the same structure in Lepidosteus, and that conse-
quently the micropylar canal is to be found at the bottom of the
funnel-shaped infolding produced by the plug.

4. Micropylar Cell.

Although no other cases are yet known in which a single cell of
the follicular micropyle-plug is so evidently differentiated from its
neighbors, as in Lepidosteus, still it is clear from the results of Eigen-
mann's ('90) studies that the existence of such a specialized cell is not
uncommon.

The most interesting question relative to the micropylar cell is that
of its physiological signification.

That it sustains some intimate and constant relation to the micropyle
itself can scarcely be doubted. Perhaps its primary function is fulfilled
by serving as a source of passive resistance to the forming membranes
in the region of the micropyle — a kind of mould for them — during
the process of their formation, therefore a mechanical device for pro-
ducing a micropylar funnel. In that case it would doubtless often be
more than the single micropylar cell on which devolved the function ; it
would be rather that plug-like accumulation of granulosa cells, with the
micropylar cell at its apex, which attains such an extensive development
in Lepidosteus and some other cases.

But the very fact that one cell is generally, if not always, differen-
tiated more than the rest, suggests that the function referred to may
not be the only one, — perhaps, indeed, not the primary one. There
are two other possible functions which are naturally suggested in this
connection.

Concerning the first of these ,i may be said that it still remains to be
shown to what extent the micropylar canal and its funnel are the result
of an exclusively progressive process of development ; whether, in other
words, any part of this structure is produced by a process of resorption.
Such a process would not be without a parallel. At least Leuckart ('55,
pp. 108, 216, 247) has asserted in most positive terms that the micropyle
of certain insects' eggs is not to be found in the chorion from the very
beginning of its formation, but that it arises after the production of the
chorion by means of resorption *

1 More recently, it is true, Korschelt ('84, pp. 421, 422) has shown that the
micropyle in Meconema varians is formed by a single cell, and he apparently leaves
no room for a process of resorption, since he says : " Die Entstehung des Canals ist
wohl so zu denken, dass die Zellen schon fruhzeitig einen Fortsatz ausstrecken, der

MUSEUM OF COMPARATIVE ZOOLOGY. Ill

The fact that Eigenmann ('90) has been unable to discover a micro-
pyle in the earlier stages of the formation of the egg membranes in fishes
may also point in the same direction. I would not wish, however, to
place too much weight upon such negative evidence ; it requires exten-
sive and indeed the most exhaustive examinations to make such" testi-
mony satisfactory. Especially am I compelled to this reserve, in view
of the fact that Cunningham ('86a) has found the micropylar apparatus
well developed at a relatively early stage in the formation of the zona
in the case of Myxine glutinosa ; but it will be observed that he says
(p. 61) : "This cellular projection is covered by a thin membrane continu-
ous with the vitelline membrane, and is not in immediate contact with the
germinal disk." An actual opening does not exist, therefore, at the time
of which he speaks. Although I have found in M. australis at an ap-
parently early stage in the development of the zona a deep infolding of
that membrane, as described above, still I have not satisfied myself in
the single specimen sectioned that there is an orifice through the mem-
brane at this stage of development. But on this observation I would
not care to speculate were it not confirmed by Cunningham's studies
on more extensive and I presume histologically more favorable material,
for I know how easily one may be deceived as to the existence of so
minute a structure as that with which we have to deal.

The facts which I have given above do have a certain weight with me
as rendering it possible that in Myxine at least the micropylar canal, in
the strict sense of the word, is not present until near the maturity of
the ovum, and that consequently it may be the function of the cell
nearest to the bottom of the funnel — the micropylar cell — to absorb
so much of the already formed membrane as is necessary to allow the

anfangs nur kurz ist, spater mit dem Diekerwerden des Chorions und dem entspre-
chenden Zuriickweiuhen der Epithelschicht aber langer und langer wird."

In his final paper, Korschelt ('87, p. [43] 223) suggests a method of reconciling
Leuckart's views with his own observations: "Die Beobachtung Leuckart's, nach
welcher die Mil: ropy lkanale sich nicht von Anfang an am Chorion finden sollen,
liesse sich vielleicht mit nnseren Befunden in Uebersinstimmnng bringen. Wir
erkannten in mehreren Fallen, dass die Masse des in der Bildung begriffenen
Chorions eine durchaus weiehe und plastische sein muss. Deshalb ware es leicht
denkbar, dass die Zellfortsatze, welclie die Kanale entstehen lassen, nicht von
Anfang der Bildung an vorhanden waren, sondern erst spater in die weiehe Masse
des jungen Chorions hinein entsendet wiirden. Dann wtirde es ein Stadium geben,
in welchem das Chorion eine ununterbrochene Oberflache besasse. Seine Ansicht,
das die Mikropylkanale an dem bereits gebildeten Chorion durch Resorption
entstehen sollen, diirfte Leuckart wohl aufgegeben haben, sobald er die Entste-
hungsweise der Porenkanale der Eischale kennen lernte."

112 BULLETIN OF THE

passage of the spermatozoon.1 I realize that this is a speculation on
very narrow foundations ; for even if it could be shown to result from
absorption, it might be the protoplasm of the ovum, not the granulosa
cell, which accomplished the work. There are, however, still more seri-
ous objections to this view, which, though not disproving it, render it
very doubtful. The fact that in general pore-canals and orifices in cu-
ticular secretions are the results, not of resorption, but of the previous
existence of protoplasmic projections, makes it probable, without positive
proof to the contrary, that the same would be true in this case.

The serious, and indeed, as it seems to me, insurmountable objection
to considering the whole micropylar funnel as the result of absorption, is
the condition which it exhibits in Lepidosteus, where there is a very
gradual diminution in the thickness, not only of the zona, but also of
the villous layer. It is not probable that any process of absorption
could result in diminishing the thickness of both layers so evenly with-
out affecting their mutual relations, unless perchance it should be
imagined that the zona was absorbed through the agency of the yolk,
and the villous layer by means of the granulosa cells. But even that
assumption would not help the case very much, for it would still have
to be explained why the shorter villi retained all the parts of the longer
ones, and in nearly the same proportions.

While, then, the conditions clearly preclude the possibility of looking
upon the micropylar apparatus in general as resulting from a process of
absorption, it by no means follows that the micropylar canal may not be
produced by such activity.

The other purpose which it has occurred to me the micropylar cell
may subserve, is to facilitate the penetration of spermatozoa. Not pre-
cisely that a minute drop of slimy substance, resulting from the degen-
eration of this cell and covering the orifice of the narrow canal, would
offer less resistance than water, but that its presence might prevent the
occlusion of the orifice by the accidental introduction of impenetrable
substances without itself offering any serious obstacle to the free en-
trance of the fertilizing element.

o

If one were to attempt a phylogenetic explanation of the micropylar
funnel and canal in bony fishes, he might reason somewhat as follows.

1 In Cunningham's Figure 3, the cells of the granulosa plug which form the
layer nearest the yolk — four of them being cut in the section figured — are all
larger than the remaining cells of the plug, but I am unable to say that any one of
them is the largest of all.

MUSEUM OF COMPARATIVE ZOOLOGY. 113

The development of a persistent egg membrane impervious to sperma
tozoa would evidently be possible only with the concomitant production
of one or more orifices; for without such provision no egg could be fer-
tilized, and the transmission of such tendencies would clearly be impos-
sible. That would necessitate the development of the micropyl© by
what I should call an exclusively progressive method. It would not
imply any regressive or resorbent process. How, then, could one find
reason for claiming any such process 1 I believe it would only be neces-
sary to assume that the zona radiata in its original development subserved
some useful end during the development of the ovum, in order to form an
idea of the possible course of events which has led to the present con-
dition. Imagine eggs at oviposition provided with a zona radiata which
remained or had become penetrable by spermatozoa; such eggs would be
in the most favorable condition for fertilization, but on account of the
condition of the zona they would be poorly protected against external
agencies. If, under these conditions, a portion of the zona radiata in
some eggs should become more resistant, even to the point of preventing
the entrance of spermatozoa, the eggs thus modified would be better
protected from injurious external influences than those which remained
in the original condition, and yet they would be almost as readily fertil-
ized as the latter, provided some portion of the zona remained, as at first,
penetrable. In short, the advantages of such a changed condition would
be greater than the disadvantages, and consequently in the long run the
more favorable condition would predominate. Evidently the optimum
protection would have been reached when a region no larger than that
absolutely necessary to admit a single spermatozoon, had been left for
that purpose. But this process of restriction in the area accessible to
the spermatozoa may easily have been accompanied by another process,
which may have begun as early as the former. The zona was assumed
to remain, or become at the time of oviposition, penetrable to spermatozoa.
It seems to me entirely reasonable that a process tending to modify a
portion of the zona and make it more readily penetrable should be set
up in the ovary, and that such eggs in the matter of fertilization alone
would have some slight advantage over eggs less easily penetrable. If
now these two tendencies were operative at the same time, — the one
serving to soften a part of the zona, in order to make it the more readily
penetrable, the other to harden another portion, to make the egg less
subject to adverse environment, — the former would become localized
by the encroachment of the latter until at length there would be only
a limited area in which the process of softening went on; but this might
vol. xix. — no. 1. 8

114 BULLETIN OF THE

be — as we must believe often happens in the animal economy — corre-
spondingly intensified, until an activity which in the beginning resulted
in only a feeble modification in the condition of the zona ultimately ter-
minated in its complete liquefaction and absorption.

A single argument, which it seems to me may have some value, in
support of this hypothesis, is to be drawn from the condition of the zona
in Elasmobranch fishes. So far as I now see, the complete disappear-
ance of the zona at the maturity of the egg would be entirely in har-
mony with the hypothesis. The condition there at any rate seems to
me to favor the assumption previously made, that the zona originally had
a function distinct from that which it now appears to possess in protect-
ing the embryo after fertilization. For if not, it must be an inheritance
from ancestors which, like bony fishes, had their embryos thus protected.
There are probably few who would defend the idea that the Elasmo-
branchs are descended from bony fishes, and the evidence of common
ancestors with eggs thus protected still remains to be found.

If, as the Eussian naturalists assert, there are several micropylar open-
ings in the egg-shell of sturgeons, it may be that those fishes present a
condition which is intermediate between an extensive region of penetra-
bility and the extreme restriction which now prevails in bony fishes.

The funnel portion of the micropylar region is certainly the less essen-
tial and least constant part of the structure. It may reasonably be
considered, I believe, a secondary condition, and the explanation of its
development might lie either in the fact that it served, in a passive way,
to direct the motion of a greater number of spermatozoa toward the
actual orifice, or, possibly, that it served to preserve from accidental
removal the protective products of the degenerated micropylar cell.

Thus the micropylar canal might be regarded as the result of two to
a certain extent antagonistic tendencies, — the fittest solution of a prob-
lem requiring the fulfilment of two conditions. The micropylar funnel
could obviously be regarded as a partial compensation for the diminished
opportunities for fertilization caused by a restriction of the area available
for that purpose, and might have arisen simultaneously with the restric-
tion, or only after the latter had attained its present maximum.

MUSEUM OF COMPARATIVE ZOOLOGY. 115

Summary.

1. The first food of young gar-pikes after the absorption of the yolk
is mosquito larvae ; later, they feed on small fishes.

2. Very cold water is injurious to young gars.

3. The arched form which the body sometimes exhibits is probably
always the result of an abnormal condition.

4. The acts of catching and swallowing the prey are complicated.
Fishes are usually swallowed head first.

5. The young gar-pike lives at the surface of the water after the
absorption of the yolk-sac.

6. The emission of bubbles of gas through the gill slits is accompanied
by a rolling of the body to one side and a forward movement.

7. Analyses of the bubbles of gas emitted by young fishes, and also
of a limited amount of atmospheric air which had been used by the
fishes in respiration, showed a reduction of the oxygen to 10-15 per
cent, and the presence of only a small amount of carbon dioxide, 0-1.7
per cent.

8. Air which had been previously deprived of its carbon dioxide gave
no evidence of containing even a trace of that gas, after having been
respired. Consult the text for the conditions of experimentation.

9. It is probable from these experiments that the air-bladder respira-
tion serves to oxygenate the blood, but that the elimination of carbon
dioxide is effected in some other manner. It is possible that the two
elements of the respiratory function of higher vertebrates were succes-
sively transferred to -the air-bladder, that of oxygenating the blood being
the first to be transferred.

10. There are two egg membranes in Lepidosteus, — a zona radiata
and a villous layer, — and they are intimately joined together. Both are
radially striate, the zona finely, the villous layer coarsely.

11. Balfour and Parker were mistaken in stating that there was a
homogeneous non-striate membrane inside the striate zona, and also in
supposing that the pyriform bodies (villi) of the outer covering were
metamorphosed follicular cells.

12. The outer layer is not as thick as the zona, and is made up of
radially compressed and folded columnar structures, the villi.

116 BULLETIN OF THE

13. Each villus is composed of three parts, — head, stalk, and roots.
The roots project into the pore-canals of the zona.

14. The zona presents the usual structure of that memhrane in bony
fishes. The pore-canals are slightly enlarged and spiral at their periph-
eral ends.

15. The egg of Lepidosteus has a single micropyle, but it has been
overlooked by previous observers.

16. The micro pylar apparatus embraces a funnel and a canal. The
funnel results from an infolding and a reduction in thickness of both the
villous layer and the zona radiata. The micropylar canal is a narrow pas-
sage of uniform calibre (2 fx) and circular cross section, through the thin-
nest part of the two membranes, namely, at the bottom of the funnel.

1 7. The granulosa of the mature ovarian egg consists of a single layer
of polygonal cells, except in the region of the micropylar funnel, where it
forms a plug of cells completely filling the funnel.

18. The membrana propria of the theca folliculi is not infolded in the
region of the micropylar funnel.

19. A single large granulosa cell, the "micropylar cell," forms the
apex of the plug, and occupies the bottom of the funnel.

20. The villous layer is formed before the zona radiata. It first
appears at the surface of the yolk in eggs about 0.4 mm. in diameter,
and reaches one third its maximum thickness a year before the egg ma-
tures. It is produced by the ovum, not by the granulosa cells.

21. The number of the villi is not increased during the growth of the
villous layer.

22. The zona radiata is likewise the product of the ovum, and its
formation requires less than twelve months.

23. The name " capsule " should not be used for the zona radiata ; it
ought to be restricted to membranes outside the zona, which, like that
of the perch, are the product of the granulosa.

24. An egg membrane comparable structurally and genetically with
the zona radiata of bony fishes is to be found in representatives of all
the groups of fishes except Amphioxus. It is fugitive in selachians and
Lepidosiren, and probably in viviparous teleosts. The zona is produced
by the ovum, not by the follicular cells, and is traversed in all cases by

MUSEUM OF COMPARATIVE ZOOLOGY. 117

pore-canals, which rarely (Myxine?) branch. J. Miiller is wrongly cred-
ited with their discovery.

25. An egg membrane genetically, but not always structurally, com-
parable with the villous layer of Lepidosteus, is found in several other
cases : possibly in Petromyzon, probably in selachians and Lepidosiren,
and certainly in several teleosts. This membrane is also produced by the
ovum, and earlier than the zona.

There is some reason to believe that it exists in the herring and the
smelt (Osmerus). Hoffmann is probably in error in attributing thf
presence of villi to the eggs of Perca in October, and Owsjannikow cer-
tainly is in asserting tbat the mushroom-shaped villi in Gasterosteus are
individual cells.

26. The capsular membrane is produced, as originally defined by
J. Miiller, by the follicle or follicular cells. It has often been confounded
with the zona, and also with the villous layer.

27. Although the " tubules " in Perca have been described as possess-
ing root-like prolongations which penetrate the pore-canals of the zona,
they are genetically unlike the villi found on other eggs, being produced
by the granulosa cells alone. Hoffmann's statement to the contrary
rests on insufficient evidence.

28. A comparison of the condition of the granulosa in Blennius pholis
and Esox with that in Perca, is believed to shed some light on the prob-
able steps by which the capsular membrane is produced.

29. The most important paper on the origin of the zona and the
villous layer I believe to be that of Kolliker, whose conclusions I have
confirmed in the case of Lepidosteus. All authors who have maintained
that either zona radiata or villous layer is the product of the granulosa
I believe to be in error ; and in particular I maintain that the reasons
assigned by Cunningham to prove that the zona in Myxine is produced
by follicular epithelium are not adequate to establish his proposition.

30. It is doubtful whether the micropylar canal has been seen in
Myxine. What W. Miiller called the micropyle was the micropylar
funnel, and possibly that which Cunningham describes as the micropyle
does not embrace the canal.

31. What I have called the micropylar plug of granulosa cells was
first seen by W. Miiller in Myxine ; later it was figured, but apparently
not appreciated, by Hoffmann in Leuciscus ; it was described as hollow
by Owsjannikow in the case of Osmerus, who recognized its relation to

118 BULLETIN OF THE

the micropylar funnel ; and finally, it was described more fully for
Myxine by Cunningham. Eigenmann has found the same structure in
a number of bony fishes.

32. The micropylar cell has never before been recognized. Eigen-
mann has now found it in a number of osseous fishes, — Perca, Pygos-
teus, Esox, etc. I believe it may fairly be assumed to exist in the
greater number of those fish eggs which possess a micropyle, and that it
has an important function in connection with the formation of the micro-
pyle or the fertilization of the egg.

33. I have made the following suggestions as to the possible func-
tions and history of the micropylar apparatus : The micropyle, being
evidently a provision for the fertilization of the ovum, may have its
present structure as the result of two to some extent conflicting tenden-
cies ; one induced by the advantages of protection to the egg, the other
by the necessity of some provision for the penetration of the fertilizing
element. But the best protection is not compatible with penetrability
of the membrane at all points. Any reduction in the extent of the
penetrable surface would be favorable to protection. An optimum con-
dition would be reached when the penetrable area is reduced to a mini-
mum, and that is the diameter of the head of a spermatozoon.

The funnel may be a partial compensation for such reduction.

The micropylar plug may mechanically determine the presence and
form of a funnel.

The micropylar cell may serve to form the canal by resorption, or to
prevent the occlusion of the canal by less penetrable matter at the time
of oviposition.

Cambridge, April 7, 1889.

MUSEUM OF COMPARATIVE ZOOLOGY. 119

Postscript.

Since the completion of the present paper, I have received from the
author, Dr. J. Beard, a copy of his "Preliminary Notice, — On the
Early Development of Lejndosteus osseus." This paper was presented to
the Eoyal Society of London, April 20, 1889, and was printed in the
Proceedings of the Society, Vol. XLVI. pp. 108-118, May 16, 1889.

Dr. Beard's material was procured by him in the spring of 1888 from
the same place as that which supplied Mr. Agassiz and myself, — Black
Lake, New York.

In this preliminary notice the author does not devote much attention
to the egg membranes. What he says about the inner egg membrane
coincides with the views which I have expressed. He says that it " is
not composed of two layers either in Lepidosteus or in the sturgeon. It
is a simple zona radiata, the striae reaching to the innermost portions of
the membrane. The division into two layers, sometimes seen, is the
optical effect of thick sections."

I cannot agree with his conclusions regarding the external layer, and
am confident that his final paper will not contain proof of the accuracy
of his statements. He says : " The pyriform bodies are certainly modi-
fied cells, each with the remains of a nucleus at its outer end. These
modified cells have degenerated into a sort of glue, which causes the ex-
cessive stickiness of the newly laid eggs. ... In the ovarian egg these
' pyriform bodies ' are probably nutritive cells to the ovum, for their
outer ends near the nuclei contain a number of minute yolk particles."

As far as regards the external layer, it is difficult to conceive how
our views, whether morphological or physiological, could have been
more divergent.

120 BULLETIN OF THE

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EXPLANATION OF FIGURES.

All the figures were drawn with the aid of the camera lucida, and were made
from preparations of Lepidosteus osseus.

Mask. — Lepidosteus.

ABBREVIATIONS.

cap. Head of villus. pd. Stalk of villus.

c.-t. cp. Connective-tissue corpuscle. rx. Root of villus.

fus. mat. Maturation spindle. st. vil. Villous layer of egg membrane.

gran. Granulosa. tk.fol. Membrana propria of thecafolliculi.

m ]>y. can. Micropylar canal. vac. Vacuole.

m py. ci. Micropylar cell. vit. Vitellus.

nl. Nucleus. vs. g. Germinative vesicle.

nl. gran. Nucleus of granulosa cell. z. r. Zona radiata.

PLATE I.

All the figures of this plate were made from material that had not been hardened,
and all the figures except Figs. 7 and 11 are magnified 472 diameters.

Fig. 1. A surface view of a small portion of the villous layer of egg membrane.

" 2. The appearance presented by the same layer when the region near the
boundary between it and the zona radiata is in focus. Some of the
roots of the villi are seen between the stalks.

" 3. The zona radiata when the focusing is a little below its outer surface.
A few pore-canals are occupied by roots of villi and appear darker.

" 4. A portion of a radial section after being treated with weak hydrochloric
acid. Two of the villi much more elongated than the others.

" 5. A radial section of a fresh egg-shell, showing the relative thickness of
the zona radiata and the villous layer.

" 6. A portion of the same with the villous layer removed, but leaving its
roots in the spiral pore-canals. Examined in glycerine.

" 7. Portions of the villous layer removed from the zona radiata and much
swollen in water. The roots appear like a fine fringe. X 145.

" 8. The appearance of the pore-canals after treatment with hydrochloric acid.
The most of them, especially toward the margin of the figure, should
have been drawn larger but faint. A few are conspicuous from the
presence of roots of villi.

" 9. a to // and j to n, isolated villi in various stages of elongation after imbi-
bition of very dilute hydrochloric acid ; i, after soaking in water
only.

" 10. A fragment of the zona radiata deprived of the villous layer and treated
with weak hydrochloric acid until all the pore-canals except those
containing villous roots had disappeared. The zona, having become
soft, was partly crushed, so that the roots were seen obliquely, the
ends toward the top of the plate being the ones torn from the stalk.

" 11. Optical radial section of the micropylar region of a fresh egg, the wall of
the membrane beyond the micropyle being projected on the same
plane. X 145.

" 1 1". Optical cross-section of the same, at plane a of Fig. 11.

" 11''. Optical cross-section of the same at plane b of Fig. 11.

,K — Lepidosteus

PL. I.

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ABBREVIATIONS.

cap. Head of villus. pd. Stalk of villus.

c.-t. cp. Connective-tissue corpuscle, rx. Root of villus.

fus. mat. Maturation spindle. st. vil. Villous layer of egg membrane.

gran. Granulosa. th.fol. Membrana propria of theca f olliculi.

m py. can. Micropylar canal. vac. Vacuole.

m py. cl. Micropylar cell. vit. Vitellus.

nl. Nucleus. vs. y. Germinative vesicle.

nl. gran. Nucleus of granulosa cell. z. r. Zona radiata.

PLATE II.

All the figures of this plate are magnified 515 diameters.
Fig 1. Portion of a radial section through the shell of a deposited egg preserved
in 5 per cent potassic bichromate. Stained in carminic acid dis-
solved in 80 per cent alcohol. Mounted in benzole-damar.

" 2, 3. Isolation preparations of villi from a mature egg pressed from female.
The egg was let fall into 90 per cent alcohol, afterwards soaked in
water, and then stained in acetic-acid carmine. Examined in glyce-
rine. The heads were of a much brighter rose-color than is shown in
the lithographic print. In Fig. 8, c, the villi are seen edgewise; in
a, b, and d, flatwise.

" 4-6. Sections through villi of a mature ovarian egg which was preserved in
0.25 per cent chromic acid forty-eight hours, washed in water six
hours, and further hardened in grades of alcohol. Stained in alco-
holic borax-carmine (Grenacher). In Figs. 4, 5, the ends of the villi
are seen ; in Fig. 6, the sides.

" 4 Sections of stalks from the pole opposite the micropyle.

" 5, 6. Sections of stalks from near the micropyle.

" 7. Radial section of an egg preserved in Perenyi's fluid (4£ hours) followed
by alcohol and stained in alcoholic borax-carmine, showing an inner
portion of the zona radiata partly detached from the outer portion.
It is not a separate membrane.

" 8. Radial section through zona and villous layer of an egg preserved in 5 per
cent potassic bichromate, stained in carminic acid in 80 per cent alco-
hol, and mounted in benzole-damar.

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Make — Lepidosteus.

ABBREVIATIONS.

cap. Head of villus. pd. Stalk of villus.

c.-t. cp. Connective-tissue corpuscle. rx. Root of villus.

fas. mat. Maturation spindle. st. ml. Villous layer of egg membrane.

gran. Granulosa. tli.fol. Membrana propria of theca folliculi.

m pi/, can. Micropylar canal. vac. Vacuole.

m pi/, cl. Micropylar cell. vit. Vitellus.

nl. Nucleus. vs. g. Germinative vesicle.

nl. gran. Nucleus of granulosa cell. z. r. Zona radiata.

PLATE III.

All the figures of this plate were drawn from the shell of an egg preserved in
cold corrosive sublimate (4 hours) followed by alcohol, stained in Kleinenberg's
hajinatoxylin, sectioned in paraffine, and mounted in benzole-damar. All except
Fig. 3 magnified 515 diameters.

Fig. 1. Radial section, the heads of some of the villi broken off.

" 2. Tangential section through the heads, at A of Fig. 1.

" 3. Similar section of four heads more highly magnified to show the deeply
stained peripheral portion. X 750.

" 4. Tangential section through the middle region (B of Fig. 1) of the stalk.

" 5. Section parallel to preceding through the region of the roots of the
villi (C of Fig. 1). The lower portion of the figure cuts through a
deeper part of the membrane (zona) than the upper portion does. The
middle portion shows the branching roots of the villi as they enter
the pore-canals.

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ABBREVIATIONS.

cap. Head of villus.

c.-t. cp. Connective-tissue corpuscle.

fits. mat. Maturation spindle.

gran. Granulosa.

m py. can. Micropylar canal.

m py. cl. Micropylar cell.

nl. Nucleus.

nl. gran. Nucleus of granulosa cell.

pd. Stalk of villus.

rx. Root of villus.

st. ml. Villous layer of egg membrane.

th.ful. Membrana propria of theca f'olliculi.

vac. Vacuole.

vit. Vitellus.

vs. g. Germinative vesicle.

z. r. Zona radiata.

PLATE IV.

Fig. 1. Radial section through the micropyle and micropylar funnel, showing the
micropylar cell and a portion of the maturation spindle of an egg
"stripped" from the fish, preserved in 0.5 per cent chromic acid
(5 hours) followed by washing in water, and hardened in alcohol.
Stained in picrocarmine. X 515.

" 2. The second section preceding that shown in Figure 1, and passing nearly
through the middle of the maturation spindle. X 515.

" 3. View of the animal pole of an egg preserved in Merkel's fluid. The
germinal disk was rather more than half as broad as the diameter of
the egg, and its outline should have been represented more distinctly
by the lithographer ; it was of a yellowish color, but much lighter
than the rest of the egg. The micropylar funnel is seen exactly over
the centre of the disk. X about 10.

" 4. View of the micropylar funnel and contained micropylar cell of the egg,
a section of which is shown in Figure 1. X 158.

" 5. Radial section through the micropylar region and germinative vesicle of
an ovarian egg preserved in alcohol. A portion of the granulosa still
adheres to the outer surface of the villous layer. Stained in alcoholic
borax-carmine. X 158.

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ABBREVIATIONS.

cap. Head of villus. pd. Stalk of villus.

c.-t. cp. Connective-tissue corpuscle, rx. Root of villus.

fas. mat. Maturation spindle. st. vil. Villous layer of egg membrane.

gran. Granulosa. th.fol. Membrana. propria of theca folliculi.

m py. can. Micropylar canal. vac. Vacuole.

m py. cl. Micropylar cell. vit. Vitellus.

nl. Nucleus. vs. g. Germinative vesicle.

nl. gran. Nucleus of granulosa cell. z. r. Zona radiata.

PLATE V.

Fig. 1. Radial section through germinative vesicle and micropylar funnel. Ow-
ing to a distortion of the section, the curvature of the part of the
membrane shown is less than it should be. The finely granular and
vacuolated portion of the yolk (vac.) beneath the germinative vesicle
is in the centre of the egg. The egg was from an ovary which was
hardened in 0.25 per cent chromic acid and stained in alcoholic borax-
carmine. X 72.

" 2. The section following that shown in Figure 1, more highly magnified.
X 335.

" 3. Radial section through villi and granulosa of an ovarian egg preserved in
alcohol and stained in alcoholic borax-carmine. X 515.

" 4. Surface view of a portion of the granulosa from the same egg as that of
Figure 3. X 515.

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Mark. — Lepidosteus.

ABBREVIATIONS.

cap. Head of villus. pd. Stalk of villus.

c.-t. cp. Connective-tissue corpuscle, rx. Root of villus.

fus. mat. Maturation spindle. st. vil. Villous layer of egg meniDrane.

gran. Granulosa. th.fol. Membrana propria of tlieca folliculi

m py. can. Micropylar canal. vac. Vacuole.

m py. cl. Micropylar cell. vit. Vitellus.

nl. Nucleus. vs. g. Germinative vesicle.

nl. gran. Nucleus of granulosa cell. z. r. Zona radiata.

PLATE VI.

All figures on this plate are magnified 515 diameters.
Fig. 1. Radial section through the micropylar canal, somewhat oblique to its
axis. The egg was preserved in 5 per cent potassic bichromate and
stained in carminic acid dissolved in 80 per cent alcohol.

" 2-4. Three successive tangential sections through the bottom of the micro-
pylar funnel and the micropylar canal of an egg stripped from the
fish preserved in 90 per cent alcohol, and stained in alcoholic borax-
carmine. The zona radiata is closely enveloped by the yolk.

" 5-8. Tangential sections through the deeper portions of the micropylar funnel
of an ovarian egg hardened in 0.25 per cent chromic acid and stained
in alcoholic borax-carmine. In Figures 5 and 6 the sections pass
through the deep portion of the zona radiata which is not infolded to
form the funnel, but in Figures 7 and 8 only that portion of the zona
is cut which projects as a conical elevation into the substance of the
yolk. Only alternate sections were drawn.

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ABBREVIATIONS.

cap. Head of villus. pd. Stalk of villus.

c.-t.cp. Connective-tissue corpuscle, rx. Root of villus.

fus. mat. Maturation spindle. st. vil. Villous layer of egg membrane.

gran. Granulosa. th.fol. Membrana propria of theca folliculi.

m py. can. Micropylar canal. vac. Vacuole.

m py. cl. Micropylar cell. vit. Vitellus.

nl. Nucleus. i's. g. Germinative vesicle.

nl. gran. Nucleus of granulosa cell. z. r. Zona radiata.

PLATE VII.

Fig. 1. Radial section through the granulosa plug which fills the micropylar fun-
nel. From an ovarian egg preserved in 0.25 per cent chromic acid,
and stained in picrocarminate of ammonia. X 515.

" 2. Micropylar cell and outlines of the egg membranes in the region of the
micropylar funnel, from an ovarian egg preserved in alcohol. Radial
section. X 515.

" 3. Four spermatozoa, dried on the slide. X 472.

" 4. Micropylar funnel ; optical cross-section as seen from the yolk side of the
egg membranes ; showing the oval form of the funnel which is
sometimes met with. X 515.

" 5. Section of an ovarian egg through the germinative vesicle. Only one
membrane besides the granulosa present ; it is the villous layer.
Preserved in 0.25 per cent chromic acid (48 hours). Stained in
alcoholic borax-carmine. X 158.

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ABBREVIATIONS.

cap. Head of villus. pd. Stalk of villus.

c.-t. cp. Connective-tissue corpuscle. rx. Root of villus.

fus. mat. Maturation spindle. st. vil. Villous layer of egg membrane.

gran. Granulosa. th.fol. Membrana propria of theca folliculi.

m py. can. Mieropylar canal. vac. Vacuity.

m py. cl. Mieropylar cell. vit. Vitellus.

nl. Nucleus. vs. g. Germinative vesicle.

nl. gran. Nucleus of granulosa cell. z. r. Zona radiata.

PLATE VIII.

Figures 1 and 2 are from sections of an ovarian egg about 0.4 mm. in diameter
which was hardened in chromic acid. X 510.

Fig. 1. Part of the peripheral portion of a radial section in which the earliest ob-
served trace of the villous layer has made its appearance. The
membrana propria of the theca and the follicular epithelium are arti-
ficially separated from the yolk and villous projections.

" 2. Tangential section from the same egg. The section embraces connective-
tissue cells of the stroma, as well as follicular epithelium, and lias also
cut off a portion of the periphery of the yolk, with its villous pro-
jections, which last give it a dotted appearance. The nuclei of the
epithelium are often lobed. vac. indicates vacuities evidently due
to depressions in the surface of the yolk, not to vacuoles in its
substance.

" 3. Portion of a section which, owing to the wrinkled condition of the surface
of the egg, affords a surface view of the granulosa, as well as a radial
section and surface view of the villous layer. Some of the detached
villi are seen at one side. The nuclei of the granulosa cells still have
irregular lobed forms. Chromic acid preparation of an egg about
0.6 mm. in diameter. X 510.

" 4. View of the villi as seen from the surface of an egg after it has lain for
some time in water. X 472.

" 5. Amber-colored bodies found at the outer surface of the villous layer of
the egg membrane. X 472.

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ABBREVIATIONS.

cap. Head of villus. pd. Stalk of villus.

c.-t. cp. Connective-tissue corpuscle, rx. Root of villus.

fits. mat. Maturation spindle. st. vil. Villous layer of egg membrane.

gran. Granulosa. th.fol. Membrana propria of thecafolliculi.

m py. can. Micropylar canal. vac. Vacuole.

m py. cl. Micropylar cell. vit. Vitellus.

nl. Nucleus. vs. g. Germinative vesicle.

nl. gran. Nucleus of granulosa cell. z. r. Zona radiata.

PLATE IX.

Fig. 1. Section of an ovarian egg about 0 6 mm. in diameter tbrough tbe ger-
minative vesicle. The villous layer is at all points in contact with
the yolk ; but it is separated from the granulosa at intervals. The
egg was hardened in 0.25 per cent chromic acid and stained in alco-
holic borax-carmine. X 158.

" 2. Portion of a radial section through a mature ovarian ovum, hardened in
0.25 per cent chromic acid, showing the penetration of tbe roots of
the villi into the pore-canals of the zona radiata. X 515.

" 3, 4. Radial sections of ovarian eggs preserved in alcohol, showing stages
in the formation of the villous layer. The eggs were somewhat more
than 0.5 mm. in diameter, and were stained in alcoholic borax-car-
mine. X 510.

" 5. A portion of Figure 1 enlarged. The outlines of the granulosa cells,
especially on the side toward the villi, are much too sharp. X 515.

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No. 2. — On the Egg Membranes and Micropyle of some Osseous
Fishes. By Carl H. Eigenmann.1

At the suggestion of Dr. E. L. Mark, I undertook the study of the
development of the micropyle and egg membranes in some of the bony
fishes.

The eggs of the following species were examined : Amiurus catus,
Tachisurus sp. (1), Catostomus teres, Notemigonus chrysoleucus, Caras-
sius auratus, Clupea vernalis, Alosa sapidissima, Fundulus heteroclitus,
F. diaphanus, Apeltes quadracus, Pygosteus pungitius, Lepomis mega-
lotis, Morone americana, Esox reticulatus, Anguilla anguilla rostrata,
Cyclogaster 2 lineatus, Gadus morrhua, and Hippoglossoides platessoides.
In many of these species the eggs were not in a condition favorable
for tracing the development of the micropyle or even the membranes.
My account will be confined to the eggs of Amiurus catus, Notemi-
gonus chrysoleucus, Clupea vernalis, Fundulus heteroclitus, Pygosteus
pungitius, Perca americana, Morone americana, Esox reticulatus, and
Cyclogaster lineatus.

I am indebted to Dr. Mark for the use of his manuscript abstracts
of the papers on egg membranes published before 1881.

It has long been known that fish ova are provided with a membrane,
the zona radiata. The eggs of certain fishes have, in addition to and
outside of the zona radiata, a second membrane which bears in some
cases long filaments, in others short processes which serve to attach the
eggs to foreign bodies.

Fundulus heteroclitus and F. diaphanus.

The fact that the eggs of some fishes are provided with long filaments
was first noted by Haeckel ('55). He found them on the eggs of many
species of Scomberesocidse, but mistook their position, describing them
as thin fibres lying inside the egg membrane (zona radiata). A con-
nection of the fibres with cells could not be traced.

1 Contributions from the Zoological Laboratory of the Museum of Comparative
Zoology at Harvard College, under the Direction of E. L. Mark. — No. XVI.

2 Liparis of authors.

vol. xix. — no. 2. 9

130 BULLETIN OF THE

Kblliker ('58) corrected the mistake made by Haeckel as to the posi-
tion of the filaments.

Hoffmann ('81) found filaments on the eggs of Heliasis, Gobius, and
Blennius.

Ryder ('82c) described the filaments of the eggs of Belone longirostris,'
and, in passing, mentioned the probability of their existence in the eggs
of Mugil albula. He afterwards ('86*) found them on the eggs of Fun-
dulus heteroclitus, and has also ('83) shown that the eggs of Menidia
(Chirostoma) notata are provided with four of them.

I have examined eggs of Fundulus heteroclitus at intervals of about
two weeks from October, 1887, till June, 1888. The eggs undergo
scarcely any change between October and April. A series taken between
April 1st and June 1st shows all the stages covered by the longer period.
The filaments can best be studied in fresh material. They appear in
the form of hyaline threads, which are more highly refractive than any
other part of the egg membrane. In an ovary of October 27 there were
filament-bearing eggs in three stages of development.

In the smallest eggs — about 0.16 mm. in diameter — in which
filaments can be seen (Plate I. Fig. 1) they appear as hyaline dots, or as
conical bodies with rounded bases, uniformly distributed over the entire
surface. They either lie wholly below the granulosa, or the tips of the
longer ones may lie in between the granulosa cells (Fig. 8). In this
stage the diameter of the threads is much greater than the thickness of
the membrane, which can scarcely be distinguished in sections. I was
not able to discover sheaths enveloping the filaments such as Haeckel
describes for the Scomberesocidee. In other slightly larger eggs belong-
ing to this same stage of development (Figs. 2-4, 6) the filaments are no
longer conical, but appear in the fresh condition as short, curved threads
equally blunt at both ends.

In the second stage, the eggs being intermediate in size between those
just mentioned and the largest, the threads (Fig. 5) are of about the
same thickness as those of the earlier stage, but they are much longer,
and taper near the free end. They do not seem to be closer together
than in the smaller eggs. The filaments are bent in a more or less
regular manner, first to one side and then to another. On stained sec-
tions it was to be seen that the threads usually follow the margins of the
granulosa cells, and that they are correspondingly curved (Fig. 6).

On the largest eggs — about 0.4 mm. in diameter — the filaments are
much longer, and cover about as much of the surface of the egg as they
leave exposed. They are so long and so tortuous that it is almost

MUSEUM OF COMPAEATIVE ZOOLOGY. 131

impossible to follow a single filament throughout its whole length. It
often happens (Fig. 10) that several filaments are parallel to each other
for a considerable distance. In sections the filaments are found to lie
in between the bases of the granulosa cells, and also to rise between
these cells nearly to their outer sui'faces.

In the ripe ovarian eggs the basal ends of the filaments pass directly
through the granulosa layer, and the greater part of the filament thus
comes to lie between the outer portions of the granulosa cells, or even
quite outside of them (Fig. 9). The regularity of their windings can-
not be seen as well as in eggs of the third size. The filaments are of
varying lengths, but most of them are several times as long as the
diameter of the egg. The distances between filaments are not materially
altered during the growth of the egg ; but since the surface of the egg
increases during its development to many times the size which it had
when the filaments first appeared, the total number of the latter must
also be greatly increased. The earliest stages in the formation of new
filaments would be difficult to find after the egg has reached its second
stage, because they would be hidden by the larger filaments.

In ripe eggs forced from the ovary, the filaments extend out from the
egg for some distance, and then form a network, several filaments deep,
over the whole surface (Fig. 11).

Concerning the origin of the filaments it may be said that they do
not have any connection with the granulosa cells at any stage of their
growth (Figs. 3, 4, 6, 8). In tangential sections it is seen that they
arise at places corresponding to the boundaries between two or three
cells. In a ripe egg examined in the fresh state under pressure (Fig. 12)
indistinct processes are seen to radiate from the base of each filament,
forming a stellate figure. In no case, either in fresh specimens or sec-
tions, could the filaments be traced into the substance of the zona radi-
ata. They are outgrowths from a thin membrane which lies outside of
the zona and is formed before the latter, not processes of the zona itself.

When the filaments first make their appearance, the egg membrane,
as stated above, is much thinner than the diameter of a filament, and
the granulosa cells are lens-shaped, barely touching by their mar-
gins (Fig. 8). In the largest eggs found in the ovary of April 2d, the
granulosa was about 8 //. thick, but the egg membrane had only reached
the thickness of 2 fx. That it is radially striate is rather to be in-
ferred than directly seen. In places the outer surface shows slight
elevations at regular distances, which I believe to be prolongations of
granulosa cells sunk into the radial canals (Fig. 13). While the largest

132 BULLETIN OF THE

eggs of April 2d were only about 0.4 mm. in diameter, and therefore
scarcely exceeded in size those of October and November, the largest
ovarian eggs of May 2d measured over 0.8 mm. Between May 1 and
June 1, — by which time the eggs have reached their full size, — the
growth is still more rapid. The egg membrane of early May eggs meas-
ures about 6.5 fj. in thickness, and has distinct pore-canals.

There exists an exceedingly thin outer membrane overlying the zona
radiata. It was discovered in the examination of fresh ripe eggs, in
which the striation of the zona itself could be seen much better than
in sections of hardened eggs. In one instance, in which the zona of a
fresh ripe egg was ruptured, this overlying membrane was left intact.
It is with this membrane that the bases of the filaments are continuous.

In view of this condition in Fundulus, and of the fact that other pro-
cess-bearing eggs (Cyprinidae and Gasterosteida?) possess a thin outer
membrane, it would be interesting to re-examine the eggs of the Scom-
beresocidse, of Menidia, and of Mugil to find whether they do not also
possess this structure.

The outer surface of the fresh ripe egg of Fundulus heteroclitus shows
a network of lines (Fig. 7). This appearance is doubtless due to the
presence of superficial ridges, which in radial sections have the appear-
ance of minute projections fitting in between the bases of the granulosa
cells (Fig. 9). Where two or more lines meet, there is a thickening.
The whole arrangement bears a superficial resemblance to the appear-
ance presented near the surface of the zona in the perch (Fig. 31). In
the case of the latter, however, the thickenings correspond in position
to filaments, each of which corresponds to the middle of a granulosa
cell, whereas in Fundulus heteroclitus the thickenings correspond in po-
sition to the boundaries between granulosa cells. From the position of
the filaments in Fundulus it is probable that, like the ridges, they are
outgrowths of the outer structureless egg membrane. It is evident from
what has been said that there is a fundamental difference between the
filaments found in Perca and those in Fundulus. In Perca they owe
their origin to the granulosa, and are formed after the zona has nearly
reached its full growth ; in Fundulus, on the contrary, they owe their
origin to the activity of the egg itself, and they begin to be formed
before the zona.

Pygosteus pungitius.

After Haeckel had described the long filaments peculiar to the eggs
of the Gobiesocidse, Kolliker ('58) described external appendages in the

MUSEUM OF COMPARATIVE ZOOLOGY. 133

eggs of Abramis brama, Chondrosteus nasus, Squalinus argenteus, Cobitis
barbatula, Gobio fluviatilis, Cyprinus rufus, and Gasterosteus pungitius.
In all these species he found the appendages inserted in a very thin
membrane, which ultimately lies just outside the zona radiata and which
makes its appearance before the latter.

The most important paper on Pygosteus is that of Ransom ('67). He
studied Gasterosteus pungitius and G. leiurus, and found that the eggs
of the two species do not differ greatly. He says that in the oviduct the
eggs are surrounded by a viscid layer, and that the zona radiata lies be-
low this layer. The zona is in contact with the yolk except in ripe eggs,
in which a thin homogeneous membrane covers the yolk and follows the
constrictions at the time of cleavage. The micropyle and the dotted
appearance of the egg membrane were first made out in eggs j^" thick,
and in eggs ^ho" m diameter the membrane could be separated from the
yolk. The button-shaped processes can be made out in eggs somewhat
less than T| V (0.17 mm.) in diameter. They are attached to the outer
surface of the yolk-sac by a bright, highly refractive point. In the case
of the smallest ova there are on an average seventy buttons, in that of
the largest two hundred and seven. They serve to attach the egg to
foreign substances. Ransom describes and figures the micropyle.

Owsjaunikow ('85) found that in ovarian eggs the granulosa cells cover
the micropyle. In fully grown eggs only a single membrane is present,
while in the younger ones the zona seems differentiated into two layers,
owing to the fact that the zona is laid down by successive additions.
The pores do not appear till the membrane has attained considerable
thickness, and they are then much finer than in the ripe egg. The
mushroom-shaped processes are maintained by him to be cells that pos-
sess nuclei which are colored red with carmine. From the base of the
process a thread can be traced into the zona radiata, In young eggs
the processes consist principally of a nucleus attached to a filament. He
does not believe that they are derived from the zona, but thinks they
come from the granulosa ; why he thinks so is not stated. Inside the
zona he has found the zonoid layer of His.

I have examined ovarian eggs of fishes taken in November, December,
and April. A few days after the spawning, in early April, the ovaries
contain a considerable number of eggs (about 0.55 mm. in diameter) in
which the formation of the yolk is well advanced. These are evidently
destined to be laid before the recurrence of the next annual spawning
season, for they are much larger than any of the ovarian eggs found in
December. These eggs show no signs of degeneration, and their pres-

134 BULLETIN OF THE

ence can therefore hardly be explained as due to their failure to pass off
with the first lot of eggs laid ; nor can they be eggs which properly belong
to the first set of spawn, as their size in comparison with that of the
mature eggs (1.1 mm.) sufficiently pi'oves. Therefore I believe that, as
Ransom has inferred, these fishes deposit eggs more than once during
the season.

The ovaries are most available for study after the first set of eggs are
deposited. As in the case of Fundulus heteroclitus, all stages of growth
are shown in ovaries taken during a period extending from one or two
months before till a short time after spawning, — the months of March
and April.

In eggs 0.15 mm. (Plate I. Fig. 14) or more in diameter there are
two membranes, — an outer more highly refractive, and an inner stri-
ated one. In many sections the two are artificially separated (Fig. 15a).
In ripe eggs the outer membrane had either entirely disappeared, or its
structure had become so much like that of the true zona that the two
could not be distinguished from each other. Their total thickness is
from 15 to 18 /a. In many sections of ripe eggs an outer layer, much
thicker than the outer layer seen in the earlier stages of development,
was in places separated from the rest of the zona. If it represents the
outer membrane of the earlier stage, then the latter must undergo a
great change in its later development, for it is now much thickei", and
is traversed by the same pore-canals as the deeper portion.

The rivet-shaped processes which are found in the region of the
micropyle are inserted, as Kolliker says, in the thin membrane which
lies outside the zona, and which is formed before the latter makes its
appearance. They take a much deeper stain than the thin membrane,
but I have seen nothing which would warrant one in claiming that
they contain each a nucleus. The smallest egg in which these processes
could be seen had a diameter of about 0.14 mm. ; only a single thin,
structureless membrane was to be made out in this stage. The largest
eggs examined had a diameter of about 1 mm.

When the processes make their appearance, the granulosa is so thin
that it is difficult to determine from surface views whether they lie
above or below it ; but radial sections show that they lie below. There
is no such constant relation between the processes and individual cells
of the granulosa as to suggest the origin of the former from the latter ;
but at a later stage the heads of the rivets occupy nearly the same
plane as the nuclei of the granulosa cells (Fig. 16), and therefore appear
to have an intimate connection with the granulosa cells. When the

MUSEUM OF COMPAEATIVE ZOOLOGY. 135

granulosa is torn from the egg membranes, as, owing to the shrinkage of
the egg, it frequently is, the processes no longer show the same sharp
outer margins. Their edges are often frayed, and are not stained as
deeply as when the granulosa and the membranes are in their normal
relations to each other. With the separation of the granulosa the thin
outer membrane is sometimes torn (Fig. 15a); and whether torn or
not, it is often separated from the inner membrane. This may be due
to the fact that the processes are from the beginning adhesive, and
have thus acquired an intimate secondary relation to the cells of the
granulosa. In such sections it can be clearly seen that the rivet-shaped
processes are joined to the outer membrane and not to the zona, though
their bases have projected into the zona for a greater or less distance.
When the granulosa is torn from the egg membranes, the processes
always, even in the smallest eggs, remain attached to the membranes
rather than to the granulosa. I have been able to find neither the
nuclear structure within nor the prolongations from these processes
which Owsjannikow has described.

I have not succeeded in finding the micropyle in eggs that were much
less than 0.4 mm. in diameter; in such the zona has an average thick-
ness of about 5 p. The portion immediately surrounding the micro-
pyle shows a considerable local thickening. Owing to the variation in
the thickness of the zona in different regions of the same egg, and to the
inconstancy of the position of the micropyle in relation to this varia-
tion, it sometimes happens that the zona at the micropylar region has
already reached a thickness of 10 or 11 jx.

It is a noticeable fact, that at this earlier stage the micropyles of
nearly all the eggs were cut radially when the sections were made
in planes perpendicular to the axis of the ovary. Furthermore, the
micropyles uniformly lie in the half of the egg opposite the side of
attachment.

In the vicinity of the micropyle the zona becomes thickened by the
elevation of its outer surface, the deeper surface undergoing no change of
direction. At a distance of about 10 fx on either side of the' micropylar
canal it attains its greatest thickness, and then its outer contour curves
inward until it becomes continuous with the wall of the micropylar
canal. The inner end of the canal is sometimes slightly enlarged
(Figs. 19-22).

At this stage the pore canals of the zona radiata do not seem to be
modified in direction in the region of the micropyle ; they are all
radially arranged. The outer membrane could not be distinguished in

136 BULLETIN OF THE

this region ; it probably is entirely wanting in the area immediately sur-
rounding the micropyle. The granulosa cells are two or three layers
deep in the vicinity of the micropyle, and a single cell larger than the
others is always to be found directly above the canal. It usually sends
a prolongation into the canal itself (Figs. 18, 21).

In eggs about to be laid, the greatest thickness of the zona in the
vicinity of the micropyle is approximately 24 /n, and the thickening in
this region is not so conspicuous as at the earlier stage. The zona bends
inward slightly, so that its inner surface no longer forms a simple
curve. The micropylar passage through the zona presents three re-
gions : a shallow funnel-shaped depression, which occupies the outer
third of the layer ; a narrower tubular portion, which is a prolonga-
tion of the bottom of the funnel, and is rounded at its lower end ;
and finally a very narrow canal, which traverses the inner sixth or
eighth of the zona, and opens at the apex of the low elevation of the
inner surface (Fig. 18).

The outer or funnel-shaped portion is wholly filled even at this
advanced stage by the single large micropylar cell which was seen at
the earlier stage (Figs. 18, 21).

Perca.

.ne egg of the perch has been a favorite subject for study. Almost
every writer on teleostean ova has examined it. Von Baer ('35, pp. 6, 7)
first described it as having a double membrane, the outer portion being
traversed by long narrow dark spots (:' dunklern Flecken ").

Miiller ('54) gives a fuller account. He separates the membrane into
an inner, the zona radiata, and an outer, the capsule. The outer sur-
face of the zona is described as being covered with exceedingly small
cylindrical projections. These are doubtless nothing but the elevations
between the pore-canals, which are rather wide on the outer half of the
zona. The capsule is radially traversed by small spiral tubes, which
are enlarged and funnel-shaped at both ends. Transverse filaments are
sometimes seen between these radial tubes. On applying pressure, yolk
granules were forced into the'spiral tubes, but in no case was any yolk
matter forced between the tubules ; from which he concludes that the
capsule must be closed between them.

Kolliker ('58) discusses the origin of the " tubules." He considers
them to be outgrowths from the follicular cells, and the substance between
them as a secretion from those cells. He denies the statement made by
Miiller, that they are hollow, but has seen the anastomosing filaments

MUSEUM OF COMPARATIVE ZOOLOGY. 137

described by him. The tubules are independent of their jelly matrix,
and in chromic acid preparations they can be separated from the latter.
When the eggs are deposited, the granulosa cells probably fall off, leav-
ing shallow depressions having polygonal outlines, from the centres of
which " tubules " arose.

Ransom ('68) described the canals passing through the outer portion
as having a double contour for each wall, and as tilled with material
containing vacuoles ; but they do not seem to him to convey anything
either fluid or solid into or out of the egg. This outer layer is separable
only by tearing it from the yolk-sac (zona), and does not leave a dis-
tinct outline. The tubes divide at their inner terminations into branch-
like roots, and adhere closely to the zona radiata. The internal ends are
not expanded as Miiller described, and it is rarely that filaments pass
from one to the other. He supposes that the granules seen by Miiller
were only vacuoles. The eggs when deposited are arranged in the form
of hollow tubes with the micropyles all turned to the inside.

His ('73) mentions having seen the micropyle, but neither figures nor
describes it.

Brock ('78) describes the zonoid layer, and finds its striations inter-
mediate in fineness between those of the villous layer and those of the
zona. Judging by his drawing of Alburnus lucidus there are about three
striations in the zonoid layer to four in the zona. The latter, he says,
makes its appearance before the villous layer.

Hoffmann ('81) finds that in October the zona and the villous layer
are of equal thickness. The latter is said to be composed of numerous
small projections which correspond exactly to the villi of the Cyprinoids.
At the free ends of the villi lie the granulosa cells. In February the
zona is differentiated into two layers, of which the inner is four times as
thick as the outer. There arise from the outer layer long fibres with
triangular bases and with their distal ends expanded to form a continu-
ous layer on which the granulosa cells rest. Each filament corresponds
to, but is not a process of, a granulosa cell.

Owsjannikow ('85) recognizes the usual divisions of the egg membrane.
The contents of the distal ends of the filaments ai*e granular, which has
given rise to the belief that they are nuclei. The filaments end ex-
ternally in funnel-shaped enlargements described by Miiller. He suc-
ceeded in forcing granular matter from the yolk into their deep ends.
The latter divide and enter the pores of the zona, through the whole
thickness of which they can be traced. He states (p. 7) that, contrary
to Hoffmann's belief, the filaments are derived from the granulosa. In

138 BULLETIN OF THE

a subsequent part of his paper (pp. 29-31), where he gives an account of
the development of thb ovarian egg, his statements seem to be conflict-
ing as to the relation of the spiral canals to the granulosa cells, but at
the end he repeats that the canals are outgrowths of cells as stated by
Kblliker. The interstitial matter (Zwischensubstanz) is arranged in
lamellae which are parallel to the surface of the egg. By the swelling
of the lamellae fissures arise which have the appearance of processes
from the canals.

I have studied the ovarian eggs of Perca killed in October, February,
and May. It is probable that the formation of the egg membranes is
less advanced in the American species of this latitude than in the Euro-
pean species at a corresponding season.

Contrary to Hoffmann's statement that in October the capsular layer
and zona are of equal thickness, not a trace of the capsular layer, dis-
tinct from the granulosa, could be found at this time of the year. The
zona is well developed, and is differentiated into two layers of about
equal thickness. The outer layer is radially striate, while the inner
appears to be structureless. The granulosa cells lie immediately in
contact with the zona radiata (Fig. 23, Plate III.). I have not been
able to find the micropyle in October eggs.

In February the zona remains practically as it was in October, but
vacuoles — which may be caused by the method of treatment — are to
be seen in the inner portion (Fig. 25, Plate III.). They are much flat-
tened radially, and thus suggest an approach to a stratified condition of
this portion of the zona. The radial striations of the outer half of the
zona are more strongly marked than at the earlier stage, and much
fainter striations may also be seen traversing the inner half. The lat-
ter, though less distinct, are just as numerous as, and continuous with,
those of the outer half. At this date the capsular layer is already well
developed, but it has attained only half the thickness which it has in
May.

Up to the month of May the thickness of the zona radiata has not
changed, but the pore-canals can now be more readily traced passing
entirely through it. They still remain much more evident in the outer
than in the inner half of the zona. This is due to the greater calibre
of the canals, not to their being farther apart in the outer half.

The different descriptions of the capsular layer are in part due to the
fact that it presents different conditions according to varying circum-
stances. The radially arranged spiral structures traversing this layer
arise as funnel-shaped tubules, one beneath each cell of the granulosa.

MUSEUM OF COMPARATIVE ZOOLOGY. 139

In the eaiTy stages of their development the tubules have a more or
less spiral course, while in the later stages they become more nearly
straight. In February eggs (Fig. 25, Plate III.) their inner ends are
slightly expanded, and terminate in a thin structureless film overlying
the zona. In radial sections of eggs taken in May, they often appear
triangular at the base, and their contents divide into branches which
enter the pores of the zona. The " filaments " connecting the canals
are sometimes much more abundant than at others. In the vicinity of
the micropyle one finds on tangential sections (Fig. 31, Plate II.) that
the tubules at or near their bases are joined to each other by what
appear like slender filaments, but these may be the cut edges of nearly
perpendicular membranes. This results in the production of an irregu-
lar network with meshes of variable size and shape, at the angles of
which the spiral tubules are located.

The micropyle was seen in eggs taken in February and in May.
Immediately surrounding it, the zona radiata is thickened by a slight
elevation of its internal surface (Fig. 24, Plate III.). The micropyle con-
sists of a funnel-shaped opening in the zona with the wide end directed
outward. In some cases the inner end of the canal also flares slightly.
In a February egg in which the micropylar region was somewhat distorted
(Fig. 26, Plate II.) the micropyle seems to have been composed of two
regions, separated from each other by a distinct shoulder, the inner
end of the outer portion being much wider than the outer end of the
inner portion. The granulosa cells and their tubules are greatly crowded
above this region (Fig. 24, Plate III.). At some distance on either
side of the micropyle it is to be seen that the outer funnel-shaped ends
of the canals begin to be more elongated than in other parts of the egg,
and continue to increase in length up to the micropyle. The nuclei of
the granulosa cells, which are situated near the bottom of the funnel-
shaped expansions, also become more and more elongated as one ap-
proaches the centre of the micropylar region, and at the same time they
come closer to the zona radiata. The effect of this is to produce in radial
sections through the micropyle the appearance of an immense funnel-
shaped depression in the whole capsular layer (Fig. 24). But the ap-
pearance is misleading ; there is no such broad depression ; the granulosa
cells of this region extend outwai'd beyond their nuclei until they reach
the theca folliculi at the same level that the neighboring cells do. The
thickness of the capsular layer is therefore not changed in the vicinity
of the micropyle, and the theca folliculi does not bend inward, but
stretches over this region with a uniform curvature. The granulosa

140 BULLETIN OF THE

cells stain more deeply than the inter-tubular substance of the capsular
layer. This peculiarity is very serviceable when one is searching for
the micropyle. Notwithstanding the absence of a broad depression,
there is a narrow irregular canal left in the centre between the modified
granulosa cells, which can best be seen upon sections tangential to this
part of the egg. (Figs. 27-32, Plate II. Compare Explanation of Fig-
ures.) The appearance is similar to what one might imagine would
result if the central cell of this region had dropped out of its original
place. That such a cell has not wholly disappeared, but has simply
lost its peripheral connection with the wall of the theca, is rendered
probable by the presence of a peculiar cell at the bottom of this canal.
Directly over the micropyle, in contact with the zona and filling more
or less completely its micropylar depression, lies a single cell of large
size. Its nucleus is more nearly spherical than the nuclei of the other
cells, and it is not stained as deeply as they are. (Fig. 24, Plate III. ;
and Figs. 26, 31, Plate II.) There can be no doubt that it is a
peculiarly modified granulosa cell.

Morone americana.

The egg membrane of the white perch has never been described, but
Ryder ('82) has described the micropyle.

There is only a single membrane, the zona radiata, but it is composed
of two distinct layers, both of which are traversed by pore canals. The
eggs examined were taken from fishes caught in February, April, and
May. In February the ovary contained eggs in four stages of develop-
ment ; in the older stages there are well developed membranes. Eggs
of 0.16 mm. in diameter have a single homogeneous membrane 1.2 p
thick. When they have reached a diameter of 0.28 mm. the zona is
composed of two layers (Fig. 33, Plate II.), a very thin inner and a
thicker outer one ; together they measure 39 p in thickness. By the
time the eggs have reached a diameter of 0.10 mm. (Fig. 34, Plate II.)
the total thickness of the membrane is more than doubled ; that of the
outer layer is 49 /x and that of the inner 39 /x. The outer layer is
formed first and takes a deeper stain. It does not increase much in
thickness after the appearance of the inner layer, and in the older eggs
it contains vacuoles. The inner is at first apparently homogeneous, but
with its great increase in thickness there appear in it the radial stria-
tions characteristic of the zona. The granulosa cells are small and low,
and have flattened nuclei situated in the middle of the cell.

MUSEUM OF COMPARATIVE ZOOLOGY. 141

Esox reticulatus.

The egg membrane of Esox was first described by Aubert ('53). He
says the shell of the egg is a thin, transparent punctate membrane, which
closely envelops the yolk and in sections exhibits radially placed streaks.
After lying in water some time, an outer very thin granular membrane
makes its appearance.

Lereboullet ('54) describes two membranes, the outer of which is
pierced by microscopic tubes. The inner is a simple extremely thin and
amorphous envelope, which has no homologue in the perch.

Eeichert ('56, p. 94) states that the membrane discovered by Aubert
surrounding the zona radiata is to be found on all eggs of this species,
but that it is in the fresh condition entirely homogeneous.

Kolliker ('58, pp. 84 and 85) maintains the existence of a thin outer,
resistant layer in all fish eggs, and was able to isolate it in fresh eggs of
Esox.

Ransom ('68) says that in Esox the egg membrane is similar to that
of Gasterosteus ; he also, as I think erroneously, supposes the thin
outer membrane to be homologous with the " Eikapsel " of the perch.
He figures the micropyle.

Finally, His ('73) described for the zona radiata concentric as well as
radial strise.

The eggs examined by me were taken from the ovary in February.
Leaving out of consideration the smallest eggs, 0.063 mm. and less in
diameter, which have no membrane except the granulosa, the ovary
contained eggs in three stages of development, respectively about 0.50,
1.00, and 1.50 mm. in diameter. In eggs of the first stage the zona
radiata is about 3 /x thick and very faintly striate. There is no evidence
of its being differentiated into concentric layers. At the micropyle (Fig.
35, Plate III.) it reaches a thickness of 7 p. Very generally the yolk is
more or less retracted from the zona by the action of the hardening re-
agents, so that a narrow space, which varies a good deal in thickness over
different parts of the egg, is left between the two structures. Spanning
this interval are numerous fine threads, which have the appearance of
being prolongations of the substance of the yolk continued into pore-
canals of the zona. This is a condition which remains at subsequent
stages, aud will therefore be discussed further on. The granulosa cells
are still thin, and their nuclei much flattened.

In the second stage (Fig. 36, Plate III.) the zona has a total thickness
of 11 or 12 ix, and is distinctly differentiated into two layers, the outer of

142 BULLETIN OF THE

which is only about one fifth as thick as the inner. The latter is faintly
stained, and distinctly striate radially ; the outer is deeply stained, and
striations are usually not to be seen in it, but on favorable sections, espe-
cially such as are very thin, the striations may frequently be made out
to pass continuously through the whole thickness of both layers. Upon
this point there is not the least doubt, so that it is certain the outer layer
in question is truly a part of the zona, and I have been unable to find in
ovarian eggs any membrane intervening between this and the granulosa
cells. In sections of the micropylar region, the inner portion of the zona
radiata exhibits vacuoles elongated in the direction of the pore-canals.
In this region the latter are not strictly radial, but converge towards the
outer end of the micropylar canal. Inside the zona there is a region to be
seen which bears some resemblance to a membrane with coarser (more
distant) striations than those of the zona. It varies in thickness on dif-
ferent parts of the egg, and corresponds, I believe, to the sub-zonal space
seen in the eggs of the first stage ; but it may represent the zonoid
layer of His.

The membranes of eggs of the third or oldest stage (Fig. 37) differ
somewhat from the conditions just described. The vacuoles of the zona
radiata, found in the second stage near the micropyle only, are here
found over all portions of the egg ; they are always most numerous near
the inner surface, aud are not found at all in the outer fifth of the
membrane. They are more or less regularly arranged in series parallel
with the surface of the zona. Kolliker ('58, p. 84) attributed the pres-
ence of such vacuoles in the pore-canals to the effect of fresh water on
the zona.

The granulosa cells in the second and thh'd stages have nearly spheri-
cal nuclei, which lie at their distal ends (Fig. 37, Plate III.). Below
the nuclei, tapering columns of granular protoplasm extend to the zona
radiata. These columns are separated by less deeply stained tracts of
substance, but the boundaries of the columns are not sharply marked.
The appearance is as though the columnar cells were being gradually
metamorphosed into an intercellular substance. This condition is evi-
dently an approach to that found in Perca.

The micropyle was found in eggs of both the first and second stages.
In the first stage (Fig. 35, Plate III.) the zona is twice as thick around
the micropyle as in other regions. This thickening results in a consid-
erable elevation of the inner surface of the zona, the outer surface being
only very slightly changed. The micropyle is a wide canal, the outer
third of which tapers rapidly and is continuous with the inner two

MUSEUM OF COMPARATIVE ZOOLOGY. 143

thirds, which taper only slightly from without inward. The micropylar
canal is partially filled with a plug of substance which appears to be con-
tinuous with the yolk. The granulosa cells overlying the rnicropyle do
not appear different in size from those which envelop the rest of the egg,
but a single cell is sometimes seen to overlie the rnicropyle in addition
to the regular layer of granulosa cells. In the second stage (Fig. 36,
Plate III.) the micropylar canal is narrower than in the first; it no
longer tapers gradually from the outside inward, but is slightly nar-
rowed at two points, one near the outside and one at its deep end. By
the retraction of the yolk from immediate contact with the zona near
the micropylar canal in the case of one of the eggs, a space was formed
through which could be traced a cord of substance continuous with that
which occupied the canal itself. The portion of the substance which trav-
ersed this space was funnel-shaped, with the wide end uext the yolk. The
thickness of the zona does not now differ so greatly in different regions as
at the first stage. At some distance from the rnicropyle in the egg last
mentioned (Fig. 36), the inner surface of the zona was raised rather
abruptly ; nearer the rnicropyle it was slightly depressed, but the mar-
gin of the canal was raised in the form of a low cone, which thus occu-
pied the centre of a very shallow inverted crater, the rim of which was
formed by the outer circular elevation. Above the rnicropyle in the
granulosa was a large spheroidal space nearly filled with a granular mass
somewhat denser than the yolk. The mass was slightly contracted, leav-
ing a narrow space at its periphery. I am in doubt whether to regard it
as a cell or not, since no nucleus could be detected. On both sides of this
granular mass there were several highly refractive homogeneous bodies
(Fig. 36, x x). It is however doubtful if they have any significance in
relation to the rnicropyle. The granulosa cells at this stage are tall
and have elongated nuclei, which are broad at the exterior end, and
taper towards the egg membranes.

Notemigonus chrysoleucus.

The ovary of this species contained ova in four stages of development
on May 9th. In all but the smallest eggs the zona radiata was present.
The largest had a diameter of 0.6 mm., and the zona varied gradually
from a thickness of 2 /x on one side of the egg to that of 4 ^ on the
opposite side. The pore-canals are very fine, being almost invisible in
balsam preparations.

The rnicropyle was observed in only a single case ; it was found in
the middle of the thickest portion of the membrane, which is exactly in

144 BULLETIN OF THE

the middle of the attached side of the egg. The direction of the inner
surface of the zona was not altered in the vicinity of the micropyle
(Fig. 38, Plate II.), but its outer surface exhibited a broad circular
depression, by which the thickness of the zona was diminished about one
half. The micropyle proper at the centre of the depression appeared
as a narrow canal of uniform calibre. Between the zona and the yolk
there was a narrow space, probably formed by the contraction of the
yolk ; beneath the micropylar region, this space was abruptly enlarged
into a hemispherical depression. Across this space the radial strands of
protoplasm characteristic of almost all the spaces between the zona and
the yolk were plainly visible.

The granulosa, which over all other parts of the egg is composed, as
usual, of a single layer of cells, is thickened in the region of the micro-
pyle. As the direction of the long axes of their oval nuclei show, the
cells near the margin of the micropylar depression in the zona have
their peripheral ends inclined toward the axis of the micropyle. The
cells which fill up the depression have larger and more elongated nuclei,
and the obliquity of the latter has become so great that, the depression
appears to be filled with a granulosa layer two or three cells deep. It
would seem that in this case the single micropylar cell found in other
eggs was represented by a number of enlarged granulosa cells.

Clupea vemalis.

The chief interest in the egg membranes of this species centres in the
presence of a thin, highly refractive, structureless membrane overlying
the zona radiata of eggs in an advanced stage of development (Fig. 39,
Plate III.). This outer membrane is intimately connected with the gran-
ulosa cells, so that it usually retains its connection with the granulosa
when the latter is artificially separated from the zona. In all such cases
slender striations extend from it to the zona radiata. The appearance of
these markings is such as to show clearly that they are prolongations of
the substance of the outer membrane, and there can be little doubt that
the projections penetrate the pore canals of the zona radiata, from which
they are partially withdrawn by the artificial separation of the two mem-
branes. This structural condition suggests an explanation for simi-
lar appearances beloiv the zona radiata in Esox and other fishes, and
between the zona radiata and an inner layer in Amiurus (Fig. 45) and
Ictalurus. It will be more fully discussed later.

MUSEUM OF COMPARATIVE ZOOLOGY. 145

Cyclogaster lineatus (Liparis lineatus Auct.).

The ovaries of this species contain ripe eggs in May, the time at
which I examined them. The largest eggs were about 0.63 mm. in
diameter, the membrane averaged about 0.043 mm. in thickness. The
zona radiata seems to be filled with small spaces connected by the much
finer radial canals (Fig. 40, Plate III.), the spaces causing the latter to
appear moniliform. Near the inner and outer margins of the zona the
canals are simple tubes, as in most other fishes.

The eggs next in size are 0.25 to 0.30 mm. in diameter; their zona is
always only half as thick on one side as it is on the opposite, the change
in thickness being nowhere abrupt. In eggs of this stage the zona is
traversed by simple pore-canals, which are indistinct near its outer sur-
face. In some cases (Fig. 41, Plate III.) the transition from the inner
to the outer portion is so abrupt that the zona appears to be composed
of two layers of unequal thickness, — an outer, thinner, more nearly
homogeneous and unstained, and an inner which is thicker, more dis-
tinctly striate, and usually faintly stained.

The micropyle (Figs. 42-44, Plate III.) was observed only in eggs
about 0.16 mm. in diameter. As in the case of Pygosteus it seems to" lie
in a plane perpendicular to the long axis of the ovary. The micropyle is
a long narrow tube, with parallel sides, in a local thickening of the zona.
This increase in the thickness of the zona affects the outline of the inner
surface more than that of the outer, and is entirely independent of the
above mentioned gradual change in thickness between opposite poles of
the egg. It is produced principally by additions to the inner surface of
the zona. The outer surface is slightly elevated at a little distance from
the micropyle, but is abruptly depressed immediately over it. The reg-
ularity in the arrangement of the nuclei of the granulosa cells is dis-
turbed in the immediate vicinity of the micropyle, where the whole layer
is slightly thickened. Usually an enlarged single nucleus lies immedi-
ately above the micropylar canal (Fig. 44).

On the Number of Egg Membranes.

The views held concerning the number of egg membranes in teleosts
have been many and various. Authors have generally been agreed about
the presence of a membrane perforate with radial canals, the zona ra-
diata ; but doubts have been raised by Ryder whether this membrane
is always present. He ('82c) found no striations in the egg membrane of

VOL. XIX. NO 2. 10

146 BULLETIN OF THE

Belone lougirostris or ('84, p. 457) the cod, and states ('85, p. 145) that
the eggs of Ganibusia patruelis do not possess any membrane. I have
found striations in the membrane of the fresh cod egg. It may be stated
here that the striations of the zona sometimes show plainest in fresh
eggs, sometimes not until reagents have been applied. Haeckel says, for
forms related to Belone longirostris, that the membrane is structureless,
but that it is covered with minute black dots. These dots were doubt-
less pore-canals seen from the surface. The zona radiata of Osmerus
eperlauus was found by Buchholz ('63) to consist of an inner and outer
portion, joined together in the micropylar region only. On deposition
of the eggs the outer membrane is turned wrong side out, and serves
to attach the eggs to foreign substances. These conditions have been
redescribed by Cunningham ('86). Hoffmann ('81) found that the zona
is differentiated into two layers in all adhesive eggs, the outer portion
being ultimately transformed into a viscid mass.

Ryder ('86) describes a peculiar arrangement of the egg membranes
of Ictalurus albidus. He says : " The egg-membrane is double, that is,
there is a thin inner membrane representing the zona radiata, external to
the latter and supported on columnar processes of itself, which rest upon
the inner membrane ; there is a second one composed entirely of a highly
elastic adhesive substance. The columns supporting the outer elastic
layer rest on the zona, and cause the outer layer to separate very dis-
tinctly from the inner one." I have found similar conditions in Amiurus
catus (Plate II. Fig. 45), but am inclined to think that the two mem-
branes represent the outer and inner portions of the zona radiata ; for
the outer shows the striations peculiar to the zona, and the columnar
layer is of varying thickness. The inner membrane, being closely asso-
ciated with the yolk, would cling to it when the yolk contracts ; the
protoplasm in the pore-canals being partially withdrawn would give rise
to these columnar processes. Where the two membranes were separated
for a considerable distance, the columnar structure was destroyed. Simi-
lar conditions obtain in the eggs of Clupea vernalis, but in this case the
columnar structures lie between the zona radiata and a thin outer homo-
geneous layer which is in contact with the granulosa. There cannot be
the least doubt concerning the meaning of the columnar layer in Clupea
vernalis, for the two membranes lie directly in contact in some parts of
the egg. The peculiar structures in Ictalurus and Amiurus doubtless
have an origin and meaning similar to that of Clupea.

The eggs of all the species of fishes examined by me possess a perfo-
rate zona radiata. The radial striae could never be made out on the

MUSEUM OF COMPAKATIVE ZOOLOGY. 147

first appearance of the egg membrane. The absence of striae in these
younger eggs may be accounted for by assuming, as Reichert has sug-
gested, that the zona radiata is a later growth, and that the imperforate
membrane of younger eggs is a different structure, or that during the
earlier stages the material composing the membrane is less dense, al-
lowing the food material to have ready access to the yolk. Granting
for the moment that the zona grows by apposition of layers from within,
the latter view is the more probable, because in the perch the inner
portion of the zona is not perforate even after the outer is distinctly so,
and in most cases the pore-canals are much more distinct and wider in
the outer than in the inner portion of the zona. The meaning of the
pore-canals, in the intra-ovarian egg at least, needs little discussion. In
most of the sections prepared, where the granulosa cells are slightly
raised from the zona radiata, processes of the granulosa cells can be seen
to enter the pore-canals.

Various membranes have been described for different fishes as over-
lying the zona radiata. The peculiar capsular layer of the perch has
been seen by all authors who have examined the eggs of this fish. It
was first described by Von Baer ('35).

Rusconi ('36) describes a thin membrane overlying the ovarian eggs
of Cyprinus. Aubert ('53) saw an outer membrane on eggs of Esox
which had lain in water some time. Kolliker ('58) succeeded in isolat-
ing this membrane in the case of Esox.

Reichert ('56) discovered that whenever processes are present, as
in many cyprinoids, they are set in a thin outer membrane. Kol-
liker ('58) confirmed this statement, and added that this outer mem-
brane is developed before the zona radiata. Reichert also found that
the membrane of the smallest membrane-bearing ovarian eggs is not
striate, and concluded that the zona radiata must be a secondary for-
mation.

Vogt ('42) was the first to describe a membrane within the zona
radiata. He found that in the eggs of Coregonus palea and Salmo
umbla this membrane cannot be readily seen until after the eggs have
been in water for some time, and that it passes (p. 29) gradually into
the germ. Ransom ('56) found a similar structure in eggs of Gaste-
rosteus pungitius, in which this inner membrane takes part in cleavage.
Eimer ('72a) claims to have isolated this vitelline membrane, which he
saw in trout, pike, white-fish, and perch. Oellacher C72) also succeeded
in separating it in the brook trout. I believe that the structures de-
scribed by Vogt, Ransom, Eimer, and Oellacher are, as others have

148 BULLETIN OF THE

maintained, not to be considered as vitelline membranes, but as tbe
superficial part of the protoplasm of the egg.

His ('73) found that the cortical layer of the yolk in many ovarian
eggs is more finely grauular than the rest of the yolk, and that it is
radially striate. This outer portion of the yolk he called the zonoid
layer. Many others have seen similar structures. According to the
accounts of some authors the zonoid layer is found only in eggs which
are not mature, and even then it is not always present.

The condition of the egg membranes in Amiurus and in certain stages
of Esox has suggested the idea that similar appearances may in some
cases have given rise to a belief in the existence of a zonoid layer when
there really was none. A partial withdrawal of the egg protoplasm
occupying the pore-canals produces an appearance which at first sight
suggests the presence of a striate membrane internal to the zona; in
fact, I at first supposed it to be a distinct membrane, and was the more
easily misled because in some cases it seems to be of nearly uniform
thickness. However, more careful study showed that it was not a mem-
brane, and that the appearance was due to fine threads of highly refrac-
tive substance stretching across a space between the inner surface of the
zona and the yolk. There are two things especially which make it im-
possible for me to believe that this is a normal condition : the great
variability in the thickness of the supposed membrane in different parts
of the same egg, and the fact that the radial striations are due to a sub-
stance which is more highly refractive than the substance, if any, filling
the intervening spaces. If, on applying reagents, there is great contrac-
tion of the yolk, either it is torn from the protoplasm in the pore-canals,
or the protoplasm contained in the pore-canals is suddenly withdrawn
from them and distorted ; in either case, there would be no appearance
of a zonoid layer. If, however, the protoplasm should not be withdrawn
from all the pores, but should in the case of many remain stretched
across the space between the zona and the yolk, as might no doubt fre-
quently happen, we should find the supposed zonoid layer more coarsely
striate than the zona, a condition described by recent authors. Such
an origin of the zonoid layer might also explain its absence in ripe eggs.
After the egg has attained its full size, the connection of the yolk sub-
stance with the canals would naturally be less intimate than at an earlier
stage, and then a contraction of the yolk would not be accompanied by
the stretching of any filaments across the space thus produced.

Scharff ('87 and '87") has recently described, within the zona radiata
in young eggs of Trigla, a zonoid layer, which subsequently disappears.

MUSEUM OF COMPARATIVE ZOOLOGY. 149

The eggs examined by me may be divided as follows : —

I. Eggs with a single membrane, the zona radiata.

a. Zona radiata a single layer of uniform structure. Notemigonus
chrysoleucus, Carassius auratus.

aa. Zona radiata differentiated into an inner and outer layer. Morone
americana, Esox reticulatus, Cyclogaster lineatus, Amiurus catus.

II. Eggs with a zona radiata and a thin homogeneous outer layer.

b. Outer membrane without appendages. Clupea vernalis.

bb. Outer membrane bearing filiform appendages. Fundulus hetero-

clitus, F. diaphanus.
bbb. Outer membrane with short appendages. Pygosteus pungitius.

III. Eggs with a zona and a thick outer layer produced by a secretion
from and metamorphosis of the granulosa cells. Perca americana.

Origin of the Egg Membranes.

Concerning the origin of the different egg membranes of fishes several
views have been held.

Vogt ('42) and Vogt and Pappenheim ('59) maintained that the zona
radiata is formed by the compx-ession of a layer of cells surrounding the
egg; Reichert ('56), Kolliker ('58), Gegenbaur ('61), and Eimer (72tt),
that it is derived from the yolk ; Thomson ('59) and Waldeyer ('70), that
it is derived from the follicular epithelium ; Ransom ('67) argued that it
cannot grow by apposition of layers from within or without, and that it
must grow by interstitial deposition of material. Whether this material
comes from ingoing or outgoing currents, he was unable to determine.

I think that the zona is undoubtedly derived from the yolk. Kolliker
found that in all the filament-bearing eggs studied by him the zona
radiata was formed after the filament-bearing membrane. I have found
the same to be true in Fundulus. In the case of Morone the outer layer
of the zona does not become much thicker after the inner layer has begun
to be formed, whereas the latter continues to grow rapidly. In the case
of Cyclogaster lineatus, where the outer layer of the zona shows columnar
structures, these do not bear any definite numerical relation to the over-
lying cells of the granulosa. The outer portion of the zona is almost
always more uniform in its structure, and stains deeper, than the inner
portion.

Reichert ('56) and Kolliker ('58) are inclined to believe that the cap-
sular layer of the perch is derived from the granulosa cells, an opinion

150 BULLETIN OF THE

with which Hoffmann ('81) does not agree. It certainly does not make
its appearance till after the zona is well developed ; if it were derived
from the yolk, its substance would first have to traverse the zona radiata.
How the nourishment for the egg could pass into the latter through the
pore-canals, and the formative substance of the villous layer at the same
time pass out through them, is scarcely conceivable. Moreover, at the
distal end of each of the villi lies the nucleus of a granulosa cell, there
being as many villi as there are cells, a fact which proves beyond a
doubt the intimate relation of the two structures.

The membrane just external to the zona in Clupea vernalis may be
considered homologous to that in Gasterosteus, Fundulus, and many
Cyprinoids, even though it does not in Clupea bear appendages as it
does in Gasterosteus. From the development of the appendages in
Fundulus and Gasterosteus it is evident that this membrane has no
connection with the granulosa cells. In these cases each of the appen-
dages does not correspond to a single cell as in the perch, nor to any
definite number of cells. If Reichert is correct in saying that the
homogeneous membrane found in young eggs is a different structure
from the zona radiata, the membrane under consideration may perhaps
be looked upon as the primitive membrane described by him. It is
certain that it appears before the zona, and I am inclined to think that
it is derived from the yolk.

Cambridge, December, 1888.

MUSEUM OF COMPAKATIVE ZOOLOGY. 151

BIBLIOGRAPHY.

Aubert, Hermann.

'53. Beitrage zur Entwickelungsgeschichte der Eische. Zeitschr. f. wiss.
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Baer, Karl Ernst von.

'35. Untersuchungen iiber die Entwickelungsgeschichte der Fische, nebst
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Holzschn. im Texte. Leipzig: Vogel. 1835.

Brock, J.

'78. Beitrage zur Auatomie und Histologic der Geschlechtsorgane der Kno-
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XXIX. 1878.

Buchholz, Reinhold.

'63. Ueber die Mikropyle von Osmerus eperlanus. Arch. f. Anal, Physiol,
u. wiss. Med., Jahrg. 1863, pp. 71-81, Taf. Ill A., Figs. 1-4. 1863.

'63a. Nachtragliche Bemerkungen iiber die Mikropyle von Osmerus eper-
lanus. Arch. f. Anat., Physiol, u. wiss. Med., Jahrg. 1863, pp. 367-372,
Taf. VIII A. 1863.

Cunningham, J. T.

'86. On the Mode of Attachment of the Ovu..^ of Osmerus eperlanus. Pro-
ceed. Zool. Soc. Loudon, for 1886, Pt. III. pp. 292-295, PI. XXX. (Read
May 4.) 1886.

Eimer, Th.

'72a. Untersuchungen iiber die Eier der Reptilien. Arcli. f. mikr. Anat.,
Bd. VIII. pp. 216-243, 397-434, Taf. XL, XII., XVIII. 1872.

Gegenbaur, Carl.

'61. Ueber den Bau und die Entwickelung der Wirbelthiereier mit partielle
Dottertheilung. Arch. f. Anat., Physiol, u. wiss. Med., Jahrg. 1861, pp.
491-529, Taf. XL 1861.

Haeckel, Ernst.

'55. Ueber die Eier der Scomberesoces. Arch. f. Anat., Physiol, u. wiss.
Med., Jahrg. 1855, pp. 23-31, Taf. IV., V. 1855.

152 BULLETIN OF THE

His, Wilhelm.

'73. Untersuchungen iiber das Ei und die Eutwickelung bei Knochenfischen.
Leipzig: F. C. W. Vogel. 1873. 4 + 54 pp., 4 Taf., 4to.
Hoffmann, C. K.

'81. Zur Ontogenie der Knochenfische. Verhandl. d. koninkl. Akad. v.
Wetenschappen, Amsterdam, Deel XXI., 164 pp., 7 Taf. 1881.
Kolliker, Albert von.

'58. Untersilcbungen zur vergleicbenden Gewebelebre, angestellt in Nizza im
Herbste 1856. Verhandl. physical.-med. Gesellschaft in Wiirzburg, Bd.
VIII. pp. 1-128, Taf. I.-IIL 1858.

Lereboullet, Auguste.

'54. Resume d'un Travail d'Embryologie comparee sur le Developpement du
Brochet, de la Perche et de l'Ecrevisse. Ann. Sci. Nat., ser. 4, Zool.,
Tom. I. pp. 237-289. 1854.

Muller, Johannes.

'54. Ueber zahlreiche Porencanale in der Eicapsel der Eische. Arch. f. Anat.,
Physiol, u. wiss. Med., Jahrg. 1854, pp. 186-190, Taf. VIII. Eigs. 4-7.
1854.

Oellacher, J.

'72. Beitrage zur Entwickelungsgeschichte der Knochenfische nach Beo-
bachtungen am Bachforelleneie. Zeitschr. f. wiss. Zool., Bd. XXII. Heft 4,
pp. 373-421, Taf. XXXII., XXXIII. 20 Sept., 1872.

Owsjannikow, Ph.

'85. Studien iiber das Ei, hauptsachlich bei Knochenfischen. Mem. Acad.

Imp. Sci. St. Petersbourg, ser. 7, Tom. XXXIII. No. 4, 54 pp., 3 Taf.

1885.
Ransom, W. H.

'56. On the Impregnation of the Ovum of the Stickleback. Proceed. Roy.

Soc. London, Vol. VII. pp. 168-172. 1856.
'67. On the Structure and Growth of the ovarian Ovum in Gasterosteus lei-

urus. Quart. Jour. Micr. Sci., n. ser., Vol. VII. pp. 1-4, PL I. Jan.,

1867.
'68. Observations on the Ovum of Osseous Fishes. Philos. Trans. Roy. Soc.

London, Vol. CLVII. Pt. II. pp. 431-502, Pis. XV.-XVILL 1868.

Reichert, Karl Bogislaus.

'56. Ueber die Micropyle der Eischeier und iiber einen bisher unbekannten,
eigenthumlichen Bau des Nahrungsdotters reifer und unbefruchteter
Eischeier (Hecht). Arch. f. Anat., Physiol, u. wiss. Med., Jahrg. 1856,
pp. 83-124, 141, 142, Taf. II., III., und IV. Figg. 1-4. 1856.

Rusconi, R.

'36. Ueber die Metamorphosen des Eies der Fische vor der Bildung des
Embryos. Arch. f. Anat., Physiol, u. wiss. Med., Jahrg. 1836, pp. 278-
288. *

MUSEUM OF COMPARATIVE ZOOLOGY. 153

Ryder, John A.

'81e. Development of the Spanish Mackerel (Gybium maculatum). Bull.

U. S. Fish Commiss., Vol. I. pp. 135-172, 4 pis. [1881] 1882.
'82. The Micropyle of the Egg of the White Perch. Bull. U. S. Fish

Commiss., Vol. I., p. 282. May 2, 1882.
'82°. Development of the Silver Gar (Belone longirostris), with Observations

on the Genesis of the Blood in Embryo Fishes, and a Comparison of Fish

Ova with those of other Vertebrates. Bull. U. S. Fish. Commiss., Vol. I-

pp. 283-301, Pis. XIX.-XXI. May 2 and 19, 18S2.
'83. On the Thread-bearing Eggs of the Silversides (Menidia). Bull. U. S.

Fish Commiss., Vol. III. pp. 193-196. 1883.
'84. A Contribution to the Embryography of Osseous Fishes, with special

Reference to the Development of the Cod (Gadus morrhua). Ann. Report

U. S. Commissioner of Fish and Fisheries for 1882, XVIT. pp. 455-605,

Pis. I.-XII.
'84a. Also separate, with title-page and cover. 149 pp., 12 pis. Washington :

Government Printing Office. 18S4.
'85. On the Development of Viviparous Osseous Fishes. Proceed. U. S.

National Museum, Vol. VIII. Nos. 8-10, pp. 128-155. Pis. VI.-XI.

25 May, 1885.
'86. On the Development of Osseous Fishes, including Marine and Fresh-
Water Forms: Extracted from Ann. Report U. S. Commissioner of Fish

and Fisheries for 1885. pp. [1]-[R6], Pis. I.-XXX. 1886.
'86a. The Development of Fundulus heteroclitus. American Naturalist,

Vol. XX. p. 824. Sept., 1886.
'87. [Same as Ryder, '86.] Ann. Report U. S. Commissioner of Fish and

Fisheries for 1885, pp. 484-604, Pis. I.-XXX. 1887.

Scharff, Robert.

'87, On the Intra-ovarian Egg of some Osseous Fishes. (Rec'd Nov. 17,

1886. — Abstract.) Proceed. Roy. Soc. London, Vol. XIV. No. 249,

pp. 447-449. 1887.
'87a. On the Intra-ovarian Egg of some Osseous Fishes. Quart. Jour.

Micr. Sci., Vol. XXVIII. pp. 53-74, PI. V. Aug., 18S7.

Thomson, Allen.

'59. [Article] Ovum in The Cyclopaedia of Anat. and Physiol., edited by
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Note.— Part I., pp. 1-80, was issued in 1852; Part II., pp. [81]-[142], in
1855.

Vogt, Carl.

'42. Embryologie des Salmones. Neuchatel. 1842. 6 4- 328 pp., 8vo.
Avec Atlas, fol. obi. de 7 pis.
Being Tome I. of L. Agassiz, Histoire Naturelle des Poissons d'Eau douce de
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154 BULLETIN OF THE MUSEUM OF COMPARATIVE ZOOLOGY.

Vogt, Carl, et S. Pappenheim.

'59. Recherches sur l'Anatomie comparee des Organes de la Generation chez
les Animaux Vertebres. (Depose dans les Archives de l'Acad. le 30 Dec,
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Waldeyer, Wilhelm.

'70. Eierstock und Ei. Ein Beitrag zur Anatomie u. Entwickelungsgeschiehte
der Sexualorgane. Leipzig: W. Engelmann. 1870. 8 -J- 174 pp., 6 Taf.
8vo.

EXPLANATION OF FIGUEES.

ABBREVIATIONS.

cp. Blood corpuscles.

fil. Filaments of Fundulus.

fil. vt. Filaments of vitellus.

gran. Granulosa.

m py. Micropyle.

m py. cl. Micropylar cell.

nl. gran. Nucleus of granulosa cell.

nl. m py. Nucleus of micropylar cell.

po. can. Pore-canals of the zona radiata.

pr c. Rivet-shaped processes of zona.

prj. i cl. Intercellular ridges.

spa.

Space below micropyle.

tbl.

Tubules of the capsular mem

brane in Perca.

tkc./ol.

Theca folliculi.

vac.

Vacuole.

yk.

Yolk.

z. r.

Zona radiata.

z. r.'

Zona radiata externa.

z. r."

Zona radiata interna.

All the figures were made with the aid of the camera lucida, and all except
Figs. 1, 2, 5, 7, 11, and 12 from preparations mounted in benzole-balsam. Figs. 39-
41 were drawn by Dr. Mark, and the others by the author.

Eigenmann. — Egg Membranes.

PLATE I.

Figures 1-13 are of F undid us heterocJitus.

Fig. 1. Surface view of one of the smallest filament-bearing eggs of October 27.
Diameter of egg, 0.16 mm. Examined fresh. X 750.

" 2. Surface view of another egg of the same size and date, with somewhat
larger filaments. Examined fresh. X 425.

" 3. Tangential section of an ovarian egg 0.15 mm. in diameter. The ovary
was hardened, December 23, in Flemming's chromic-osmic-acetic mix-
ture, and subsequently stained with hematoxylin. X 425. The section
is seen from its inner surface.

" 4. Tangential section of an egg from the same ovary with longer filaments.
X 425. This section is also seen from its inner surface.

" 5. Surface view of an egg of October 27, about 0.23 mm. in diameter.
Examined fresh. X 425.

" 6. Tangential section of an egg 0.25 mm. in diameter, from the same ovary
as Fig. 3. X 750.

" 7. Surface view of a ripe (June) egg from which the granulosa cells had been
removed, showing the network of ridges between their bases. Exam-
ined fresh. X 750.

" 8. Radial section of the egg represented in Fig. 3. Transsections of fila-
ments are seen at Jd. X 425.

" 9. Radial section of an egg of May 2, about 0.8 mm. in diameter. Preserved
in Perenyi's fluid, and stained with picrocarminate of lithium. X 750.

" 10. Tangential section of an egg of December 23, about 0.4 mm. in diameter.
From the ovary mentioned under Fig. 3. X 425.

" 11. Radial optical section of a ripe egg shortly after being forced from the
ovary (June 1). Examined fresh. X 50.

" 12. Base of one of the filaments of the ripe egg. Examined fresh under pres-
sure. X 750.

" 13. Radial section of an ovarian egg of November 23. Preserved in Perenyi's
fluid, and stained with Grenadier's alcoholic borax-carmine. X 750.

Figures 14-22 are of Pygosteus pungitius, all except Figure 20 being of eggs
from a single ovary, which was cut transversely.

" 14. Radial section through an ovarian egg 0.15 mm. in diameter. The ovary
was preserved in Perenyi's fluid, April 18, shortly after spawning, and
subsequently stained in picrocarminate of lithium. X 750.

" 15. Tangential section near the micropyle. X 112.

" 15a. Radial section of an egg 0 37 mm. in diameter. X 750.

" 16. Radial section of an egg 0.33 mm. in diameter. X 750.

" 17. Radial section of an egg 0.37 mm. in diameter. X 750.

" 18-22. Radial sections through the micropyles of eggs, about 0.4 mm. in diam-
eter. In Figs. 20 and 21 the micropyle is cut obliquely. X 750.

" 20 is from an ovary hardened April 4, i. e. some time before spawning.

fit

c

d

%

J)

.

a j

1

9.

.•: V.*'; ."•

•

• :

'• - . .
:.' ?

tv-A y.- • . ••• • • >•

.

10

•

12

y*. /•• /.-'

13

rll i «

' / ' '

14

16.

• 15

15 =

18

/'•"'

••'

I /

20.

</•

19

• I in in .

21.

22

!

spa.

Space below micropyle.

tbl.

Tubules of the capsular men:

brane in Perca.

thc.fol.

Theca folliculi.

vac.

Vacuole.

yk.

Yolk.

z. r.

Zona radiata.

Eioenmann. — Egg Membranes.

ABBREVIATIONS.

cp. Blood corpuscles. /?rj. z c/. Intercellular ridges.

fil. Filaments of Fundulus.

fil. vt. Filaments of vitellus.

gran. Granulosa.

m py. Micropyle.

m py. cl. Micropylar cell.

til. gran. Nucleus of granulosa cell.

til. in py. Nucleus of micropylar cell.

po. can. Pore-canals of the zona radiata. z.r.' Zona radiata externa.

pr. c. Rivet-shaped processes of zona. z. r." Zona radiata interna.

PLATE II.

Figures 23, 24, and 25 are on Plate III.; Figures 26-32 are from Perca.

Fig. 26. Radial section through the micropyle of an ovarian egg from Perca killed

in February. X 750.
" 26B. Section through the micropyle (?) of an egg of Perca. X 750.
" 27-32. A series of sections tangential to the surface of an egg of Perca 1 mm.

in diameter at a point somewhat to the right of the micropyle. The

portion of the sections to the right if the micropylar region lies deeper

than the portion to the left. In
" 27, the cells lying to the right of the region of the micropyle are crowded, and

have a curved band-like arrangement. The cells which contain dark

points and lie farther to the right are from the central portion of the

section, and are therefore cut across deeper than the others. In the

second section,
" 28, only the deeper, filamentous prolongations of these cells are seen. In
" 28, 29, a median pit can be traced through the centre of the column of cells

which occupies the micropylar region. In
" 30 the nucleus of the enlarged micropylar cell (nl. mpy.) is seen. In
" 31 is seen the enlarged mouth of the mycropyle (m py.) and a few cells which

lie somewhat higher and to the left of it.
" 32 is a section through the zona radiata and micropylar canal.

This egg was preserved February 15 in Perenyi's fluid, and was stained

with Czoker's alum-cochineal. X 425.
" 33. Radial section of an ovarian egg of Mnrone americana 0.28 mm. in diam-
eter. Hardened in chromic acid February 25, and stained with picro-

carminate of lithium. X 750.
" 34. Radial section of a larger egg (0.4 mm. in diameter) of Morone americana

from the same series of sections as that of Fig. 33. X 750.
" 38. Radial section through the micropyle of an egg of Notemigonus chryso-

leucus 0.63 mm. in diameter. Ovary of May 5, killed in Perenyi's

fluid, and stained with picrocarminate of lithium. X 750.
" 45. Radial section through the egg of Amiurus catus. Ovary of May 9, killed

in Perenyi's fluid, and stained with picrocarminate of lithium. X 750.

The radial markings have been accidentally omitted and fil. vl. placed

for./?/, vt.

El ' MANN V

zs.

0 -"""''■

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Eigenmann. — Egg Membranes.

ABBREVIATIONS.

cp.

Blood corpuscles.

pr j. id.

fii.

Filaments of P'undulus.

spa.

fil. vt.

Filaments of vitellus.

tbl.

gran.

Granulosa.

mpy.

Micropyle.

thc.fol.

m pi/, cl.

Micropylar cell.

vac.

nl. gran.

Nucleus of granulosa cell.

yk.

nl. in py.

Nucleus of micropylar

eel

[.

z. r.

po. can.

Pore-canals of the zona

ra

diata.

z.r.'

pr c.

Rivet-shaped processes

of

zona.

z. r."

PLATE III.

Intercellular ridges.
Space below micropyle.
Tubules of the capsular mem-
brane in Perca.
Theca folliculi.
Vacuole.
Yolk.

Zona radiata,
Zona radiata externa.
Zona radiata interna.

Fig. 23. Radial section of an egg of Perca in October, 0.5 mm. in diameter. The
ovary was hardened in 0.25 per cent chromic acid, and subsequently
stained with Czoker's alum-cochineal. X 750.

Radial section through the micropyle of an egg of Perca. The ovary was
preserved in Perenyi's fluid, May 9, and stained in carminate of
lithium. X 425. The definite line at the outer margin of the zona
radiata should have been omitted.

Radial section of an egg of Perca, 0.9 mm. in diameter. From an ovary
hardened in February. X 425.

Figures 26-34 are on Plate II.

Radial section through the micropyle of an egg of Esox, 0.47 mm. in
diameter. Ovary of February 23 killed in chromic-osmic-acetic mix-
ture, and stained with picrocarminate of lithium. X 750.

Radial section through the micropyle of an egg of Esox, 0.94 mm. in
diameter, from the same series represented in Fig. 35. X 750.

Radial section of an egg of Esox, 1.5 mm. in diameter, from the same
series. X 750.

Radial section of an egg of Clupea vernalis, 0.54 mm. in diameter. Pre-
served in Perenyi's fluid, and stained with picrocarminate of lithium.
X515.

Radial section through the egg of Cyclogaster liparis, 0.7 mm. in diameter.
Ovary of April 26 preserved in Perenyi's fluid, and stained with picro-
carminate of lithium. X515.

Radial section through the egg of Cyclogaster liparis, from an ovary of
May 7 preserved in Perenyi's fluid, and stained with picrocarminate
of lithium. X 515.
42, 43, and 44. Radial sections through the micropyles of three eggs of Cyclo-
gaster, about 0.25 mm. in diameter. Ovary of May 7 preserved in
Perenyi's fluid. X 515.

24.

25.

35.

36.

37.

40.

41.

24.

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No. 3. — Report on the Results of Dredging, under the Supervision
of Alexander Agassiz, in the Gulf of Mexico (1877-78), and in
the Caribbean Sea (1879-80), by the IT. S. Coast Survey Steamer
"Blake" Lieut.-Commander C. D. Sigsbee, U. S. N., and Com-
mander J. K. Bartlett, U. S. N., Commanding.

[Published by Permission of Carlile P. Paterson and J. E. Hilgard, Superin-
dents of the U. S. Coast and Geodetic Survey.]

XXXII.

Report on the Nudibranchs. By Run. Bergh.

Wahrend dieser Expedition wurden nur ganz wenige Formen von
Nudibranchien gefischt, aber fast alle neu nnd darunter noch dazu ein
Paar ziemlich interessante. Diese Formen waren die folgenden : —

1. Tethys leporina, L,. var.

2. Chromodoris scabriuscula, Bgh., n. sp.

3. Chromodoris punctilucens, Bgh., n. sp.

4. Chromodoris sycilla, Bgh., n. sp.

5. Phlegmodoris? anceps, Bgh., n. sp.

6. Nembrotha gratiosa, Bgh., n. sp.

7. Phyllidiopsis papilligera, Bgh., n. sp.

Fam. TETHYMELIBIM2.

TETHYS, L.

R. Bergh, Malacolog Untersuch. (Semper, Philipp. II. ii.), Heft IX., 1875, pp. 346-

362, Taf. XLV. Fig. 19-26, Taf. XLVI. Fig. 1-22, Taf. XLVII. Fig. 1. 2.
II. v. Hering, Tethys. Ein Beitrag zur Phylogenie der Gastropoden. Morpholog.

Jahrb., II., 1876, pp. 27-62, Taf. II.
R. Bergh, Notizen iib. Tethys leporina. Jahrb. d. deutschen Malakolog. Ges., IV.

4, 1877, pp. 335-339.
R. Bergh, Beitr. zur Kenntn. d. Aeolidiaden. VII. Verh. d. k. k. zool. bot. Ges.

in Wien, XXXII., 1882, pp. 67-68.

VOL. XIX.— NO. 3.

156 BULLETIN OF THE

H. de Lacaze-Duthiers, Snr le Phaenicurus. Comptes Rend., CI. I., 1885, pp. 30-35.
R. Bergh, Sur la Nature du Phasuicure. Arch, de ZooL, 2 ser., III., 1886,

pp. 73-76.
H. de Lacaze-Duthiers, Coutrib. a l'Hist. du Phaenicure. Arch, de zool., 2 ser., IV.,

1887, pp. 77-108, PL IV.
List, Zur Kenntu. d. Driisen im Fuss von Tethys fimbriata, L. Arb. aus dem zoolog.

Institut zu Graz, I. 6, 1887, pp. 287-305.

Diese merkliche aberraute Nudibraiichien-Gruppe ist erst durch die
zwei ersten der obengenannten Arbeiten naher bekannt wordeu und
diese Kenntniss ist nicht ohne wesentlichen Einfluss auf das Studiuni
der ganzen Gruppe gewesen.

Die nntenstehende Untersuchung hat wesentlich nur dadurch Inter-
esse, dass sie das Vorkommen von einer Tethys, der altbekannten oder
einer neuen Form, im westlichen Theile des atlantischen Meeres nachweisst.

T. leporina, L. var.

Tafel I. Fig. 1-3.

Hub. M. atlant. occ. (Dominica).

Von dieser Form wurde ein Individuum in der Nahe von Dominica aus
einer Tiefe von 138 Fad en hinaufgefischt.

Das in Alkohol ganz schlecht bewahrte, verdrehte, theilweise erhartete und
Papillenlose Individuum hatte eine Lange von 4.3 cm., von welchen die voile
Halfte auf dem Segel kamen, der Querdurchmesser des letzteren 3 cm.; die
Hohe der Rhinophorscheide 7 mm., der Keule 2 mm. ; die Lange der Rand-
fad en bis 10 mm.; die Lange des Mundxohres 4 bei einem Durchmesser am
Grunde von 3.5 mm.; die Breite des Riickens bis 13 mm.; die Hohe des
Korpers bis 10 mm. ; die Lange des Fusses 2.5 bei einer Breite bis fast 2 cm.,
der Vorderrand 7 mm. frei vortretend. — Die Farbe der Aussenseite des colos-
salen Segels ist gelblichweiss wegen dichtgedrangter ganz feiner gelblickweisser
Piincktchen, die gegen den Rand hin zu unregelmassigen Fleckchen fast zu-
sammenfiiessen. Die Unterseite des Segels ist hinten koblenschwarz so wie
auch das grosse Mundrohr (aussen und innen), wird dann in der mittleren
Strecke mehr braungrau, gegen den Rand hin schwarzlich und (theilweise
fleckig) schwarz ; die Randfaden des Segels meistens gelblichweiss, der Botlen,
auf dem sie sitzen, aber schwarz. Die Scheide der Rhinophorien schwarz,
mit grossen gelblichweissen Flecken; die Keule am Grunde schwarz, sonst
weisslichgelb. Der Rucken und die Korperseiten fast von der Farbe der
Oberseite des Segels, aber mehr gelblich und im Genicke so wie in der Ge-
gend des Riickenrandes starke, grosse, kohlenschwarze Flecken. Die Riicken-
papillen fehlten ganz; die Kiemen (am Grunde der Papillenfacetten) weisslich,
Die obere Seite des Fusses ringsum wie die Korperseiten gefarbt ; der Fuss-
rand weisslichgelb ; die Fusssohle braungrau.

MUSEUM OF COMPARATIVE ZOOLOGY. 157

Der grosse Segel wesentlich wie bei der typischen Tethys des Mittelmeeres ;
an der Innenssite der Randparthie stehen die Randfaden in meistens 4-6 (8)
sehr undeutlich geschiedenen Reihen; die aussersten sind ganz klein, die
innersten von bedeutender Lange ; die Dorsalen Cirrhen des Segelrandes kamen
in gewohnlicher etwas sparsamer Menge vor und von einer Hohe bis 2 mm.
Das starke Mundrohr am Vorderende (Fig. 1 a) in gewohnlicher Weise ge-
kluftet; der gahnende Aussenmund bis an den Rand und bis in die Tiefe, bia
an die schniirlochartige Pbarynxoffnung mit starken Hockerchen, nur ausnahms-
weise reihegeordnet, besetzt. Im Genick, dicht an der Gegend des hinter-
sten Theils des Segels, ziemlich weit von einander stehend, die zusammenge-
driickten, oben etwas breiteren Rhinophorien, deren vorderer Theil oben eine
Vertiefung mit umgeschlagenem Rande tragt, in welcher sich die zuriickge-
bogene Keule fand; diese letztere etwas abgeplattet, mit 11 breiten Blattern. —
Die Korperform wie in der typischen Tethys, der Riicken nur vielleicht etwas
breiter. Am gerundeten Riickenrande, wie es schien, 7 rundliche Papillen-
facetten gewohnlicher Art, die Papillen selbst aber fehlend (wie so oft bei
Exemplaren von Tethys) ; dicht neben jeder Facette zwei Kiemenbiischel, ein
vorderer kleinerer, ein hinterer grosserer ; die Kiemenbiischel wie gewohnlich.
Vor der zweiten rechten Papillenfacette die etwas hervorragende Anal-Pro-
tuberanz, neben derselben die Nierenpore. Die Kdrperseiten vorne ziemlich
hoch ; aus der Genitaloffnung ragte ein Theil des Penis etwa 2 mm. hervor.
Der grosse Fuss ganz wie bei der typischen Tethys ; eine mediane Langsfurche
fehlte nicht hinten an der Sohle.

Die Eingeweidemasse an die Korperwande durch Bindesubstanz geheftet.
Das weisslichgelbe Centralnervensystem zeigte die Hauptganglien von ein-
ander viel deutlicher geschieden, als ich es sonst bei Tethyden gesehen
habe, nur zwischen den beiden pleuralen Ganglien war die Grenze undeut-
lich. Die buccalen (vorderen Eingeweide-) Ganglien zwischen dem hinteren
Theile der Speicheldriisen liegend (Fig. Id), oval, durch' eine Commissur
verbunden, die langer als der Querdurchmesser des Ganglions war ; oberhalb
der Wurzel des nach vorne gehenden Nerven fanden sich mehrere Nervencellen
eingelagert (Ganglion gastro-oesophagale). Der Riechknoten am Grunde der
Keule des Rhinophors. Kleine (sympathische) Ganglien kamen an und
zwischen den Eingeweiden zerstreut vor, besonders im Gebiete des Geni-
talsystems.

Die kleinen schwarzen Augen an der Oberflache der Gehirnknoten nach
aussen fast sessil, oval, von 0.12 mm. grosstem Diam., mit gelber Linse, reich-
lichem schwarzem Pigmente und ziemlich grossen Retinazellen. Die Ohr-
blasen als kalkweisse Punkten aussen an der oberen Seite der cerebralen Gang-
lien neben den pleuralen gelagert, kugelformig, ganz kurzgestielt (Fig. 3),
etwas kleiner als die grossen Nervenzellen, von 0.16 mm. Diam., mit zahl-
reichen runden und ovalen Otokonien von einem grossten Durchmesser von
0.016-0.02 mm. Die Haut mit Driisencellen und Driischen iiberall reichlichst
ausgestattet.

Die Pharynxoffnung unten am Grunde der Mundrohre in die Speiserbhre

158 BULLETIN OF THE

iibergehend ; die etwas langer als die Mundrohre war; das vordere Ende (Fig.
1 6) derselben aussen schwarzlich, dann ringartig gelblichweiss (Fig. 1 c), dann
wieder und in der iibrigen Strecke schwarzlich. Die Innenseite vorne schwarz,
mit etwa 15 starken Langsfalten, die sicb vorne in den Pharynx hinein fort-
setzen, hinten an dem erwahnten, nicht ganz schmalen, fast farblosen Ringe
plotzlich anhalten ; im vorderen Theile der folgenden Strecke kamen wieder
etwa 15 starke Falten vor ; diese Falten waren von einer schwach gelblichen
Cuticula iiberzogen, die ganz fein und zierlich gefaltet war. In dem hinteren
Theile der den Schlundkopf reprasentirenden (Fig. 1 b) vorderen Strecke der
Speiserohre miindet jederseits die langgestreckte, feinknotige (Fig. 1 dd, 2)
gelblichweisse Speicheldruse ein; der Ausfiihrungsgang ganz (Fig. 2 a) kurz. —
Der eigentliche aussen schmutzig schwarzblaue Magcn 5.5 mm. lang, oval, von
3.5 mm. Durchmesser, von den gelblicben vorderen Lebern mit Ausnahme
der Mitte der Riickenseite (und des Hinterendes) bedeckt (Fig. 1 c). Ge-
offnet zeigt der Magen feine Langsfalten der Innenseite ; etwas nach vorne
findet sich rechts die Oeffnung des Gallenganges der rechten Nebenleber ;
echrag gegeniiber die Oeffnung fur die mit einander verbundenen linke
Neben- und Hauplleber. Hinten und rechts setzt sich der Magen in den
Darm fort (Fig. 1 g); die schwarze Farbe hort plotzlich und scharf am
Pylorus auf. Der Pylorustheil des Darmes ist gelblichweiss, und hier offnet
sich, dicht neben dem Pylorus, wie durch ein Schniirloch der sogenannte
zweite Magen. Dieses ziemlich grosse Diverticulum (Fig. 1/) ist gelblichweiss,
fast kugelformig, von 3 mm. Durchmesser ; die Innenseite mit einem feinen
pennaten Faltensystem. Der (Fig. 1 g) Darm erst nach unten und hinten, dann
hinaufsteigend, kurz, ziemlich weit, nur in der letzten Strecke enger; aussen
mit Ausnahme der ersten Strecke schwarzlich ; die Innenseite schwarz, mit
feinerer Langsfalten und einer starkeren, die von der Oeffnung des Diverticu-
lums anzufangen scheint. — Der Magen und der Darm von Nahrung vollge-
stopft ; dieselbe bestand aus Massen von kleinen niederen Crustaceen (Cope-
poden, Ostracoden) und Stiicken von kleinen Decapoden, mit Bruchstiicken
von kleineren Gasteropod-Schalen und Sandkornern vermischt.

Die rechte Nebenleber, wie erwahnt (Fig. 1 hi), den rechten Theil aes
Magens mit einem dicken gelblichen Lager einhiillend ; von derselben geht
(wenigstens) ein Zweig an die erste rechte Papille (und wahrscheinlich an
den (Fig. 1 h) Rhinophorstiel) ab ; diese Lebermasse offnet sich durch einen
ganz kurzen Gallengang in den Magen. Die linke, der vorigen ganz ahnliche,
Nebenleber, den linken Theil des Magens (Fig. 1 kl) einhiillend, sich nach
hinten etwas verlangerend und sich mit (Fig. 1 m) dem Ausfiihrungsgange
der Hauptleber vereinigend ; auch von dieser Leber geht ein Zweig an die
Gegend der Facette der ersten Papille ab; diese Leber offnet sich links in
den Magen. Die Hauptleber viel grosser als die vorigen, an Lange etwa 1.8 cm.
betragend bei einer Breite vorne von 11 und einer Hohe von fast 9.5 mm.;
das Vorderende schief nach rechts- hinten- unten abgestutzt und (wegen der
vordern Genitalmasse) vertieft ; das Hinterende gerundet ; nur central am
Vorderende trat die graubraune Farbe der Leber hervor, sonst war sie von

MUSEUM OF COMPARATIVE ZOOLOGY. 159

der gelblichen Zwitterdriise gedeckt ; das Organ bestand aus Lappen von ver-
zweigten Lappchen, deren Ausfiihrungsgange sich allmahlich traubenartig
vereinigen und nach und nach den central verlaufenden Hauptgallengang
bilden, welche links am Vorderende frei hervortritt (Fig. 1 m) und sich mit
der linken Nebenleber vereinigt. An den Seitentheilen des Riickens der
Mnteren Eingeweiden masse durcbbrechen mehrere Leberzweige das Zwitter-
driisenlager und steigen an die Papillenfacetten auf.

Das Pericardium und das Herz wie gewohnlich. — Die Niere mit ihrer baum-
artigen Veranstelung von schonen Kolben und Rohren den grossten Theil
der hinteren Eingeweidemasse iiberziehend und die Langsfurche derselben aus-
kleidend; in der Auskleidung von jenen viele horngelbe und braungelbe rund-
liche Concremente von einem Durchmesser von meistens 0.025-0.035 mm.
Der Ureter wie gewohnlich ; in denselben offnet sich der Pericardialtrichter,
der kurz- birnformig war, von 1 mm. Lange, gelblichweiss, mit stark durch-
schimmernden Langsfalten ; der Gang kurz, fast ohne Vegetation en der
Innenseite.

Die gelbliche, die Leber mit Ausnahme des grossten Theils ihres Vorderen-
des iiberziehende Zwitterdriise wie gewohnlich ; in den Lappchen entwickelte
Zoospermien. Der rechts am Vorderende der hinteren Eingeweidemasse ent-
springende Zwitterdrusengang an die Hinterseite der vorderen Genitalmasse iiber-
tretend. Diese letztere 9 mm. lang bei einer Hohe von 7 und einer Dicke
von 5 mm. ; am oberen Rande vorne die Prostata, hinter derselben der Knauel
der Windungen der Ampulle de3 Zwitterdriissenganges, unter dem letzteren
die Samenblase; die Hauptmasse ist von der Schleimdriise gebildet. Die gelb-
liche Ampulle durchgehends von beilaufig 0.5 mm. Diam.; aufgerollt hinter
der Prostata einen Knauel bildend, der ein wenig kleiner als die Prostata war ;
ausgerollt mass dieselbe 2.5 cm. Der aus der Theilungsstelle der Ampulle
ausgehende S^menleiter etwa doppelt so lang wie der Durchmesser der Pros-
tata. Diese letztere gelblicb, fast kugelformig, von 4 mm. Diam., mit einem
kleinen Nabel der hinteren und einer tiefen Kluft der Vorderseite, aus welcher
die Fortsetzung des Samenleiters hervortretet; die Oberflache fein kornig, der
Bau ganz der gewohnliche. Die aus der tiefen Kluft vortretende Fortsetz-
ung des Samenleiters graulich, ziemlich diinn, etwa doppelt so lang wie der
Durchmesser der Prostata, sich durch den Penis bis an 9eine Spitze windend.
Der halb hervorgestreckte Penis gelblich, lang, kegelformig; der gewohn-
liche Nebensack konnte nicht gefunden werden. Der Eiergang geschlangelt
an den Schleimdriisengang gehend, ausgestreckt beilaufig 1.5 cm. messend,
etwa so dick wie die Ampulle. Die gelbliche, sich in das Vestibulum geni-
tale neben dem Schleimdrusengange offnende Samenblase birnformig, von
etwa 5 mm. Lange bei einem Durchmesser von etwa 2.3 mm., von Samen
strotzend; der Ausfuhrungsgang fast ebenso lang, mit starken Langefalten
der Innenseite. Die Schleimdriise gross, kalkweisslich ; die Eiweissdriise
gelblich ; der Schleimdriisengang mit der gewohnlichen starken Doppel-
falte.

160 BULLETIN OF THE

Ob diese Form nun eine (locale) Varietat der bisher nur im Mittelmeere
und bei den canarischen Inseln gefundenen Tethys leporina darstellt oder eine
eigene Art, muss vorlaufig hingestellt werden. Das Erste ist wohl das wahr-
scbeinlichste, obgleich die scbwarze Farbe der Verdauungshole und Abweich-
ungen im Genitalsystem wohl aucb die letzte Annahme ermoglichten. Die so
trage und nie schwimmende Staurodoris verrucosa kommt doch auch im west-
licbsten Theile des atlantischen Meeres (unweit von Rio Janeiro) vor (Staurod.
Januarii, Bgh.).1

Fam. DORIDID^l CRYPTOBRANOHIAT^J.

CHROMODORIS, Aid. et Hauc.

Vgl. R. Bergh, Report on the Nudibranchiata. Challenger Exped., Zool., X., 1884,

pp. 64-78.
Vgl. R. Bergh, Malakolog. Unters., Heft XV. 2, 1884, pp. 64-78, pp. 347-350; Heft

XVI. 2, 1889, pp. 831-837.

Die fast immer schlanken und meistens lebhaft gefarbten Chromodoriden
haben einfach gefiederte Kiemenblatter, starke Lippenplatten, und die Rhachis-
parthie der Eadula tragt hochstens nur Verdickungen, aber keine Zahnplatten.2
Die Aphelodoriden,8 die sonst sehr ahnlich sind, unterscbeiden sich durch
mehrfach gefiederte Kiemenblatter und durch Fehlen von Lippenplatten.

Die Gattung ist bisher nur aus den warmeren (Mittelmeere) und den tropi-
calen Meeresgegenden bekannt. Sie scheint die Artenreichste Grnppe von
Doriden zu sein ; sie wird bier v/ieder durch mehrere neue Arten bereichert.

i. Chr. scabriuscula, Bgh., n. sp.

Tafel I. Fig. 11-19.

Hab. M. atlant. occidentale.

Von dieser form wurden am 24° 44' Lon. und 83° 26' Lat. (d. h. in der
Nahe von Straits of Florida) aus einer Tiefe von 37 Faden 3 Individuen
gefischt, die fast vollstandig von derselben Grosse und Formverhaltnissen
waren.

1 Vgl. Ihering, Znr Kenntn. d. Nudibranchien d. brasilianischen Kiiste. Jahrb.
f. d. Malacolog. Ges., XIII., 1886, pp. 230-233.

2 Nur die Chr. Scabriuscula, B. macht hier eine Ausnahme.

8 R. Bergh, Neue Chromodoriden. Malakolog. Bl. N. F. I., 1879, pp. 107-113.
R. Bergh, On the Nudibr. Gaster. Molls, of the North Pacific Oc. (Dall, Explor.
of Alaska), II., 1880, PI. VIII. (XVI.), Figs. 12-18.

MUSEUM OF COMPAKATIVE ZOOLOGY. 161

Die in Alkohol gut bevvahrten Individuum hatten eine Lange von 12 bei
einer Breite bis 6 und einer Hohe bis 3.5 mm., die Lange des Fusses 10 bei
einer Breite bis 2.5 mm. ; die Breite des Mantelgebrames 1.5 mm.; die Lange
der Tentakel 0.6 mm.; die Hohe der (zuriickgezogenen) Rhinopborien 1.8, der
(zuriickgezogenen) Kieme 1.5 mm. — Die Farhe war durchgehends gelblich-
weiss, die Keule der Rhinopborien und die Kieme mehr gelblich.

Die Form war langlich-oval, etwas niedergedriickt ; die Riickenseite etwas
gewblbt, iiberall bis an den Rand init ziemlich zahlreichen kleinsten conischen
Hockerchen besetzt, die am Mantelgebrame zahlreicber waren; die weit nach
vorn stehenden Rhinophorlocher, und die weit nach hinten stehende Kiemen-
spalte schniirlochartig zusammengezogen ; die Keule der Rhinopborien stark,
mit beilaufig 20 nicht diinnen Blattern ; die Kieme aus 9, einem vorderen und
jederseits 4, nach hinten an Grbsse allmahlich abnehmenden, einfach-pinnaten
Blattern gebildet; die Analpapille niedrig. Der Kopf klein; die Tentakel
kurz-cylindrisch, am Ende gleichsam eingestiilpt. Die Unterseite des Man-
telgebrames eben, mit durchschimmernden, gegen den Rand senkrecht gehen-
den Spikelziigen. Der Fuss langgestrekt, mit parallelen Seitenrandern ; der
Vorderrand mit Furche und gerundeten Ecken ; der Schwanz 2.2 mm. lang,
etwas zugespitzt. Die Genitalpapille mit zwei Oeffnungen neben einander.

Die Eingeweide schimmerten nirgends durch, waren an der Korperwand
angeheftet.

Das Centralner-vensystem zeigte die cerebro-pleuralen Ganglien kurz-nieren-
fonnig, die nach unten stehenden pedalen Ganglien grosser als die pleuralen;
die gemeinschaftliche Commissur ziemlich kurz, kaum so lang wie der Quer-
durchmesser des Fussknoten. Die ganz kurzstieligen Ganglia olfactoria un-
gewohnlich gross, fast halb so gross wie die Ganglia cerebralia; die buccalen
und gastro-oesophagalen Ganglien wie gewohnlich.

Die ganz kurzstieligen Augen ziemlich gross, mit schwarzem Pigment. Die
Ohrblasen kleiner als die Augen ; mit Otokonien gewohnlicher Art prall ge-
fiillt, unter denen ein kugelformiger, der doppelt so gross wie die anderen
war. In den Blattern der Rhinophoricn zahlreiche, auf den Rand senkrecht
stehende, gelbliche, harte Spikeln von einem Durchmesser bis 0.03 mm. Die
Riickenhaut im Ganzen und besonders die Hockerchen derselben mit ahnlichen
Spikeln stark ausgestattet.

Die Mundrohre stark, 1.5 mm. lang, wie gewohnlich. Der kurze Schlund-
kopf 1.6 mm. lang; hinten an der Unterseite trat die Raspelscheide hervor.
Die horngelbe ringartige Bewaffnung der Lippenscheibe unten viel breiter als
oben, aus den gewohnlichen, bis beilaufig 0.027 mm. langen, an der Spitze
geklufteten (Fig. 11, 12), dicht zusammengedrangten Hakchen zusammenge-
setzt. Die Zunge von gewohnlicher breiter Form mit tiefer Kluft ; in der
hellgelben Raspel 58 Zahnplattenreiben, weiter nach hinten in der starken
Scheide 46 entwickelte und etwa 4 jiingere Reihen; die Gesammtzahl dersel-
ben somit 108. In der Raspel jederseits 25 Platten, und die Anzahl weiter
nach hinten kaum 30 ubersteigend. Die Zahnplatten schwach gelblich ; die
Breite der medianen Platten 0.01, die ersten lateralen 0.016 mm.; die Hohe

VOL. XIX. — NO. 3. 11

162 BULLETIN OF THE

der aussersten Platten meistens 0.028, die Hohe der Seitenplatten bis 0.04 mm.
Es kamen wirkliche mediane, am Rande gezahnte Platten vor (Fig. 13 a, 14).
Die innerste laterale Platte (Fig. 13) mit 8-10 Dentikeln des ausseren und 4-5
des inneren Hakenrandes ; an den iibrigen Seitenplatten fanden sich, wie ge-
wohnlich, nur Zahncben am Aussenrande, aber in sehr variabler Menge, mit-
unter 5-6, mitunter nur 2-3 (Fig. 15-17) ; an den aussersten (Fig. 18)
Platten war der Grundtheil kiirzer, und unterhalb der Hakenspitze fanden
sich nur 2-3 Zahnchen. — Die langen und weisslichen Speichelariisen wie
gewobnlich.

Die Speiserohre etwa so lang wie der Schlundkopf ; der Magen wie gewohn-
lich; der Darm vor der Mitte der hinteren Eingeweidemasse hervortretend,
sein Knie in gewohnlicber Weise bildend, uud in gewohnlicber Weise ver-
laufend, gelb. — Die bintere Eingeweidemasse (Leber) 6.5 mm. lang bei einer
Hohe und Breite von 3.2 und 3.5 mm., vorne sebr schief abgestutzt und hin-
ten gerundet, (gelblich-) weiss. Die Gallenblase langgestreckt-birnformig,
weisslicb, links am Pylorus erscheinend.

Das Pericardium mit dem Herzen, die weisslichen Blutdriisen, die Niere
und der Pericardial tricbter wie gewohnlicb.

In den gelblichen Lappen der Zwitterdriise grosse Eierzellen. — Die vordere
Genitalmasse gross, etwa 4 mm. lang, von ovaler Form, planconvex, gelblich ;
am Vorderende die starken Windungen des Samenleiters. Die Ampulle des
Zwitterdriisenganges weisslich, geschlangelt. Der Samenleiter lang ; der weiss-
liche prostatische Tbeil kiirzer als der gelblicbe muskelose (Fig. 19 a); die
kurzkegelformige, ziemlich dicke glans penis am Boden des (Fig. 19 b) rau-
migen Praeputiums kaum vortretend. Die Spermatotbeke kurz-birnformig,
die Sperrnatocyste wurstformig und kleiner; der vaginale Gang lang, nach
vorne weiter, mit einer starken gelben Cuticula ausgefuttert ; die Vagina fast
so lang wie das Praeputium, doppelt so dick wie der vaginale Gang, von einei
diinneren Cuticula ausgekleidet. Die Schleimdriise gross; die Eiweissdriise
etwas mehr gelblich.

Diese Form unterscheidet sich von den allermeisten Chromodoriden durch
die harten Hockerchen des Piickens und damit durch die ziemlich starke Ent-
wickelung der cutanen Spikeln, so wie besonders durch wirkliche mediane
(rbachidiale) Zahnplatten. Auch die Auskleidung des vaginalen Ganges ist
eigentbumlich.

2. Chr. punctilucens, Bgh., n. sp.

Tafel I. Fig. 4-10.

Hab. M. atlant. occid.

Ein einziges Individuum wurde aus einer Tiefe von 37 Faden auf 24° 44'
Lon. und 83° 26' Lat. (d. h. in der Nahe der Straits of Florida) gefischt.

MUSEUM OF COMPARATIVE ZOOLOGY. 163

Das in Alkohol bewahrte Individuum hatte eine Lange von 3.5 bei einer
Breite von 1.6 und einer Hohe von 1.5 cm.; die Breite des Mantelgebrames
2 (vorne) bis 4.5 mm. ; die Hohe der (zuriickgezogenen) Rhinophorien 3, der
(zuriickgezogenen) Kieme 5 mm.; die Lange des Fusses 3 bei einer Breite
bis 1 cm. — Die Farbe der obern Seite war durchgekends olivenbraungrau
mit ziemlich zaklreich zerstreuten gelben und weissen Punkten, die oft eine
sckwarze oder schwiirzliche Areola zeigten ; am Mantelrande ein schmales,
schwarzes, seiner Lange nach durch eine weisslicbgelbe oder gelbe Linie ge-
theiltes Band ; die Unterseite des Mantelgebrames von der Grundfarbe des
Riickens oder mebr grau, hier und da schwarzfleckig ; der Rand der Rhino-
phorlocher so wie der Kiemenspalte schwarz mit gelben Punkten und Bruch-
stiicken von gelben Linien ; die Keule der Rhinophorien schwarz, am Vor-
derrande und gegen die Spitze gelblich; die Kiemenblatter schvvarzlieh, die
Rhachisparthien, die Spitze und theilweise die Rander der Blatter gelbfleckig;
die Analpapille schwarz mit gelblichem Rande. Die Korperseiten von der
Farbe des Riickens, die gelben und weissen Punkte kommen aber sehr sparsam
vor. Die Tentakel mit gelber Spitze; der Aussenmund schwarz. Die Fuss-
sohle graulich; das Fussgebrarne oben von der Farbe der Korperseiten, aber
mit starken schwarzen Flecken ; der Fussrand gelb, hier und da mit schwarzen
Fleckchen ; am Schwanzriicken zerstreute gelbe Punkte.

Im Aeusseren simulirte diese Form (in Alkohol bewahrt) ganz eine Doriopse,
nur war der Mund wie bei den Doriden, und die Tentakel kurz kegelformig (an
der Spitze, wie bei so vielen Chromodoriden, gleichsam halb eingestiilpt). Die
Form langlich, die Consistenz weich. Der Riicken etwas gewolbt, das Mantel-
gebrame ziemlich breit, wellenformig gebogen, an der Unterseite wie der ganze
Riicken eben. Die Rhinophorlocher fast glatrandig; die Keule der Rhino-
phorien kraftig, mit beilaufig 30 breiten Blattern. Die Kiemenspalte quer-
oval, fein rundzackig. Die Kieme jederseits aus 7 einfach pinnaten Blattern
gebildet, denen sich hinten eine Spirale von 13 Blattern anschliest ; diese letz-
teren etwas schmachtiger und unbedeutend niedriger als die andern, die alle
fast von gleicher Grosse waren. Hinten zwischen den Spiralen die cylindrische,
oben abgestutzte, etwa 3 mm. hohe Analpapille; rechts und vorne neben der-
selben die Nierenpore. Die Korperseiten ziemlich hoch; die Genitalpapille
wie gewohnlich. Der Fuss vorne gerundet-abgestutzt, mit feiner Randfurche ;
das Fussgebrame nicht schmal; der Schwanz stark, nicht kurz.

Das gelbe Centralnervensystem von den Blutdriisen bedeckt, in reichliche, fest
anhangende Bindesubstanz gehiillt; die Ganglien ziemlich dick. Die zwei
Abtheilungen der cerebro-pleuralen Ganglien sehr ausgepragt; die pedalen
ausserhalb und unterhalb der vorigen liegend; die pleuralen grosser als die
cerebralen, die pedalen wieder grosser als die pleuralen ; die gemeinschaftliche
Commissur weit, doppelt so lang wie der Querdurchmesser des Centralnerven-
systems. Die Riechknoten, die buccalen und die gastro-oesophagalen Ganglien
wie gewohnlich.

Die Augen fast sessil, mit schwarzem Pigment. Die Ohrblasen so gross wie
die Augen, mit Otokonien gewohnlicher Art prall gefullt. In den Blattern

164 BULLETIN OF THE

der Keule der Rhinophorien keine Spikel. In der Haut des Riickens kanien
erhartete Zellen sparsam vor.

Die Mundrohre sehr stark, etwa 6 mm. lang Lei einem Diam. hinten
von 6 mm.; aussen gelblich, innen vonie schwarz und hinten gelblich ; die
starken Retractoren wie gewoknlick. — Der sehr kraftige Schlundkopf 5.5 nun.
lang bei einer Breite von 4.5 und einer Hohe von 4.5 mm. ; das abgeplattete
Hinterende stark schriige ; von der Unterseite ragt die starke (1.1 mm.
in Diam. haltende) Raspelscheide 3 mm. nach oben und links empor. Die
runde Lippenscheibe von 4 mm. Diam., von der schon dunkel ambergelben
Lippenplatte (Fig. 4) iiberzogen, welche oben schmaler, unten (von vorn nach
hinten) viel breiter (bis 2.5 mm.) war, unten continuirlicb, oben durch einen
ganz schmalen Zwischenraum in zwei Halften geschieden. Die Lippenplatte
in gewohnlicher Weise von dicht zusammengedrangten gelblichen Stabchen
gebildet, welche (in gerader Linie gemessen) eine Lange bis zu fast 0.06 mm.
erreicbten, gebogen und in der Spitze gekluftet (Fig. 5, 6) waren. Die
Zunge breit, abgeplattet, mit breiter Kluft ; in der gelblichen Raspel 60
Zahnplatten, weiter nach hinten und in der ziemlich langen Raspelscheide 98
entwickelte und 12 jiingere Reihen ; die Gesammtzahl derselben somit 170.
Die vordersten 16-18 Reihen sehr incomplet. In den hintersten Reihen der
Zunge fanden sich jederseits bis 53 Seitenzahnplatten, und die Anzahl stieg
kaum wesentlich weiter nach hinten. Die Zahnplatten gelblich; die Hohe
der aussersten Platten 0.04-0.05 mm. betragend, allmiihlig stieg die Hohe der
Platten bis zu etwa 0. 1 mm. ; die Lange der medianen (Fig. 7 a) Verdickungen
meistens 0.035 mm. Die Zahnplatten von der gewohnlichsten Hakenform;
an den aussersten ist der Korper in gewohnlicher Weise reducirt, und die
Platten mehr aufrecht. Die innerste (Fig. 7 bb) Zahnplatte an beiden Ran-
dern des Hakens gezahnelt ; alle die iibrigen (Fig. 8, 9) nur am ausseren
Rande mit 6-10 feinen Dentikeln ; die 5-7 aussersten (Fig. 10) ohne
Dentikel.

Die weissen Speicheldrusen sehr langgestreckt, vorne etwas dicker, sich bis
an die Unterseite der hinteren Eingeweidemasse hinab erstreckend.

Die Speiserohre kaum langer wie der Schlundkopf bei einem Durchmesser
von beiliiufig 1 mm. Der in die hintere Eingeweidemasse eingeschlossene
Macjen rundlich, nicht klein. Der Darm vor der Mitte der oberen Seite die
hintere Eingeweidemasse durchbrechend, in gewohnlicher Weise A'erlaufend
und sein Knie bildend; im ganzen 7 cm. lang bei einem Durchmesser von
1.5-2 mm. — Der Inhalt der Verdauungshohle war ganz unbestimmbare thieri-
sche ]\lasse, worin Stiicke von Zahnplattenreihen des Thieres selbst.

Die hintere Eingeweidemasse (Leber) 2 cm. lang, bei einer Hohe und Breite
von 1.2 cm.; nach hinten zugespitzt ; die vordere Halite der rechten Seite
(durch die vordere Genitalmasse) stark abgeplattet ; die Substanz gelb. Die
Gallcnblase links neben dem Pylorus, sackformig, von 4 mm. Lange, graulich.

Das Pericardium gross, queroval, von 8 mm. kurzestem Diam. Die gelbe
Herzkammer von 3.5 mm. Lange. Die Blutdriisen in den Randern etwas lap-
pig, graugelb, abgeplattet; die vordere gestreckt-herzformig mit der Spitze nach

MUSEUM OF COMPARATIVE ZOOLOGY. 165

vorn, 6 mm. lang; die hintere breit, querliegend, 7 mm. breit. — Die Ver-
breitung der Niere iiber die hintere Eingeweidemasse sebr schon, die Urin-
kanimer weit; der Pericardialtrichter stark, birnformig, 2 mm. lang.

Die Zwitterdricse mit einem 0.5-1 mm. dicken, mehr gelben Lager den
grossten Theil der Leber iiberziehend; in ihren Lappchen grosse Eizellen. — ■
Die (sehr stark erhartete) vordere Ge?iitalmasse gross, planconvex, 14 mm. lang
bei einer Breite von 7 und einer Hobe von 11 mm. Am Vorderende die
ziemlicb dicke, geschlangelte, opak-vveisslicbe Ainpulle des Zwitterdriisen-
ganges. Der Samenleiter lang, gewunden, der gelblicbe prostatiscbe Theil
kiirzer als der muskulose; die glans penis kegelformig. Die Spermatotheke
von ovaler Form, von 3.5 mm. Lange ; die Spermatocyste wurstformig, gebo-
gen, ein wenig langer. Die Schleimdriise graulicbgelb und kalkweiss, die
Eivveissdriise braunlich; der ausserste Theil des Schleimdriisenganges schwarz.

Dieses Thier reprasentiert gewiss eine neue Art. Unter den wenigen bis-
her 1 bekannten Arten aus dem westlichen atlantischen Ocean (Chr. Moerchii,
B.; Cbr. gonatophora, B.) giebt es keine zu welcher sie bingefiihrt werden
konnte, und eben so wenig kann sie mit irgend einer der vielen im Mittel-
meere vorkommenden identificirt werden.

3. Chr. sy cilia, Bgh., n. sp.

Tafel III. Fig. 5-13.

Hah. M. atlant. occ. (Sin. Mexicanum).

Von dieser Form hat die Blake-Expedition 16 Meile gegen Nord von den
Jolbos-Inseln (an der Kiiste von Yucatan) ein einziges Exemplar gefischt, aus
einer Tiefe von etwa 14 Faden.

Das in Alkohol gut bewahrte, nur etwas zusammengezogene Indivi-
duum hatte eine Lange von 2.5 bei einer Breite von 1 und einer Hohe
von 1.4 Cm. ; die Hohe der (zuriickgezogenen) Rhinopborien fast 4, der
(zuriickgezogenen) Kieme 4.25 mm. ; die Breite der Fusssohle 4.5 mm. —
Die Grundfarbe des Korpers war ein sehr schones und lebhaftes Dunkel-
blau. Diese Farbe war am Riicken wie an den Seiten von zahlreicben, kalk-
weissen, diinnen, oft zerstiickelten Langslinien durchzogen; die Stiickchen
mitunter an dem einen oder anderen Ende kurz- schlingen- oder bsenformig
oder mit einem kurzen Seitenaste; zwischen den Linien kamen noch hier und
da einzelne rundliche oder ovale Fleckchen vor. Am Riicken fanden sich
etwa 9-10 solcbe Linien vor, an den Korperseiten 5-6. Der Mantelrand
(Fig. 13) so wie der Fussrand mit einer ganz abnlichen, ebenso unterbroche-
nen, kalkweissen Linie geziert. Der Rand der Rbinophorlocher weiss ; die
Rbinophorien scbmutzigblau. In dem theilweise weissen Rande der runden
Kiemenspalte endigt die grbsste Zalil der weissen Riickenlinien ; die Kieinen-

1 Vgl. die von mir vor einigen Jahren gelieferte Liste in Challenger Exped.,
Zool., X., 1884, pp. G5-72.

166 BULLETIN OF THE

blatter sehr schon blau ; ihre an der Aussenseite ziemlich breite Rhachis weiss
gerandert, der schmale innere Rhachisrand mitunter auch weiss. Die Fuss-
sohle sehmutzig gelblicb.

Die FormverJuiltnisse wie bei den meisten Chromodoriden ; das Stirnge-
brame, der Mantelrand und das Schwanzsegel schmal. Ringsum an der Un-
terseite des Mantelgebrames fanden sich grossere und kleinere, durchsichtig-
gelblicbe, kugeliormige, sessile, ungleicbgrosse Blasen (Fig. 13 aa) von einem
Durchmesser von beilaiifig 0.3-2 mm ; die grossten kamen am Schwanzsegel
vor (Fig. 13 aa); jede zeigte am Scheitel eine meistens schon unter der Loupe
sehr deutliche Oeifnung. Oberhalb und ausserhalb des Aussenmundes jeder-
seits ein gleichsam eingestiilpter Tentakel. Die etwas zusammengedriickte
Keule der Rhinophorien mit etwa 40-45 breiten Blattern. Die Kieme weit
nach hinten stehend, mit 12 schonen Blattern, von welchen das binterste Paar
kleiner, die iibrigen fast gleichgross. Im Centrum des Kiemenkreises die
niedrige (oben weisse) Analpapille, rechts und vorn neben derselben die Nie-
renpore. Der Fuss wie gewohnlich ziemlich schmal.

Das Peritonaeum farblos oder hier unci da blaulich.

Die das Centralnervensystem eng einhiillende starke Bindesubstanzcapsel mit
der Unterseite der vorderen und mit dem Vorderende der hinteren Blutdriise
innig vervvachsen. Die Ganglien an der Unterseite der ganzen Ganglienmasse
deutlich geschieden. Die cerebro-pleuralen Ganglien langlich-nierenformig,
die cerebrale grosser als die pleurale Abtheilung; die rundlichen pedalen Gang-
lien etwas grosser als die cerebralen. Die grosse gemeinschaftliche Commissur
ziemlich weit, doppelt so lang wie der Querdurchmesser des Centralnerven-
systems. Die proximalen und distalen Riechknoten wie gewohnlich. Die
buccalen Ganglien oval, fast unmittelbar mit einander verbunden; die gastro-
oesophagalen sehr kurzstielig, etwa 4; der vorigen betragend.

Die Augen mit schwarzem Pigment und schwach gelblicher Linse, durch
einen kurzen N. opticus mit dem kleinen Gangl. opticum verbunden. Die
Ohrblasen wie gewohnlich, mit zahlreichen Otokonien gewohnlicher Art. In
den diinnen und breiten Blattern der Keule der Rhinophorien kamen zerstreute
erhartete Zellen, aber keine Spikel vor.

Die Mundrohre aussen blaugrau, innen gelblicb weiss, kurz und weit; der
Diam. und die Lange etwa 5 mm. betragend. — Der Schlundkopf sehr stark,
6 mm. lang bei einer Breite von 5 und einer Hohe von 4.75 mm., von gewohn-
lichen Formverhaltnissen ; die 3.5 mm. lange, starke Raspelscheide langs des
Hinterendes des Schlundkopfes hinaufgekriimmt ; die Lippenscheibe gross,
gewolbt, mit sehr starker, griinlich- olivenfarbiger Lippenplatte. Diese letztere
einen etwa 3 mm. breiten Ring bildend oder eigentlich zwei Halbriuge, die in
der Mittellinie oben und unten durch ein schmaleres Zwischenstiick vereinigt
sind. Die Platte in gewohnlicher Weise von ganz dicht gedrangten Stabchen
mit gebogenem hakenartigem Kopf gebildet (Fig. 5) ; sie erreichten eine Hohe
bis zu beilaufig 0.04 mm.; die Stabchen der erwahnten Zwischenstiicke ganz
klein. Die Zuvge breit ; in der griinlich- olivenfarbigen Raspel 39 Zahnplat-
tenreihen, weiter nach hinten kamen dazu 41 entwickelte und 4 jiingere Reihen,

MUSEUM OF COMPARATIVE ZOOLOGY. 167

die Gesammtzahl derselben aomit 84 Die 8 vordersten Reihen melir oder
weniger incomplet. Die hintersten Reihen der Zunge enthielten (jederseits)
etwa 290 Zahnplatten, und die Anzahl stieg kaum wesentlich weiter nach
hinten. Die Zahnplatten schwach gelblich nrit etwas griinlichem Anfluge;
die Seitenzahnplatten erreichten eine Hohe bis zu 0.14 mm., die der aussersten
betrug etwa 0.06-0.08 mm. Die Rhachisparthie sehr schmal, meistens mit
einer seichten medianen Langsfalte. Die Zahnplatten von der allergewohn-
lichsten Form (Fig. 6-9) ; die Haken gabelig, der obere Ast langcr und mehr
gebogen als der untere ; unterhalb dieses letzteren eine Andeutung von feinen
Rundzacken, die nach aussen in den Reihen besonders etwas deutlicher wur-
den und selbst in feine Dentikelbildungen iibergehen konnen (Fig. 6). Die
(meistens) 5-6 aussersten Platten sind von etwas abweichender Form (Fig.
10, 11), zeigen den Haken reducirt und mit gerundetem Ende; die 1-2 aller-
aussersten haben keine Auskerbung oben (Fig. 12).

Die Speicheldriise sehr lang, sich iiber die Unterseite der vorderen Genital-
masse erstreckend, kalkweiss, diiun; vorne etwa 1.25 mm. breit, in der hin-
teren Halfte kaum halb so dick ; die ganz kurzen Ausfuhrungsgange in die
Wurzel der Speiserohre einmiindend.

Die Speiserohre diinn, etwa 14 mm. lang (bei einein Durchmesser von
0.8 mm.), ganz unten am Vorderende der hinteren Eingeweidemasse eintre-
tend und sich in die weite Leber- Magenhohle offnend. Der Darm die Leber
vor der Mitte ihrer oberen Seite durchbrechend, vorwarts gehend ; sein Knie
iiber die vordere Genitalmasse legend und dann nach hinten verlaufend ; die
Lange des Darmes im Ganzen etwa 5 cm. betragend, bei einem wechselnden
Durchmesser von 1.5-4 mm. Der weissliche Inhalt des Darmes (und der
Leberhohle) war unbestimmbare thierische Masse, mit langen und spitzen
Spikeln vermischt.

Die hintere Eingeweidemasse (Leber) war 15 mm. lang bei einer Hohe von
12 und einer Breite von 9 mm. (stark zusammengezogen), hinten gerundet,
vorne schief abgestutzt; ihre Substanz hell gelblichgrau. Die Gallenblase
horizontal an der linken Seite des Pylorus Legend, 4 mm. lang bei einem
Durchmesser von 1 mm., gelblichweiss.

Das Pericardium blaugrau. Das Herz wie gewohnlich. Die griinlich-gelb-
grauen Blutdriisen an der oberen Seite mit hell griinlichblauem Ueberzuge, die
vordere kleiner, 3 mm. breit bei einer Lange von 2.5 mm.; die hintere grosser,
gerundet-dreieckig, die Spitze nach hinten kehrend, 5.5 mm. breit bei einer
Lange von 3.5 und einer Dicke von 0.8 mm. — Die Niere wie gewohnlich ;
das pericardio-renale Organ birnformig, 1.8 mm. lang.

Die gelbliche Zwitterdriise als ein diinnes Lager die Leber fast vollstandig
iiberziehend ; in den Lappchen der Druse kamen reife Zoospermien vor. —
Die vordere Genitalmasse 8 mm. lang bei einer Hohe von 6 und einer Breite
von 4 mm.; die dunkelblauen Hauptausfiihrungsgange noch 4 mm. lang ; das
Hinterende der Masse wird zum grossten Theile von der grossen Samenblase
gebildet, die aber oben und an der ausseren (rechten) Seite von den Win-
dungen des Samenleiters gedeckt wird. Die Ampulle des Zwitterdrusen-

168 BULLETIN OF THE

ganges opak-gelblichweiss, wurstartig, etwas zusammengebogen, ausgestreckt
an Lange 6 mm. bei einem Durchmesser von beilaufig 0.75 mm. messend.
Der lange, viele langere unci kiirzere Windungen machende, weissliche prosta-
tische Tbeil des Samenleiters ausgestreckt etwa 5-6 cm. lang bei einem fast
durcbgehenden Diam. von 0.5 mm.; der mehr gelblicbe muskulose Tbeil nur
beilaufig 12 mm. lang und etwas dunner. Der letztere gebt in den sicb nach
und nacb verdickenden, am Ende blauen Penis iiber, der eine Lange von 4.5
bei einem Diam. (vorne) bis zu 1.5 mm. batte ; nur der unterste Tbeil des-
selben ist hobl (Praeputium), aucb an der Innenseite blau, am Boden der
Hohle die gewohnlicbe, wenig vortretende papillare glans. Die Spermatotheke
gross, kugelforniig, von 5 mm. Diam., die Ausfiihrungsgange nicht lang ; die
Spermatocyste birnformig, 2.5 mm. lang, ziemlicb kurzstielig. Die Schleim-
und Eiweissdriise kaum die Halfte der ganzen Genitalmasse betragend, 5.2 mm.
lang bei einer Hobe von 4.8 und einer Breite von 3 mm., gelblicbweiss und
weiss ; der weite Scbleimdrusengang aussen und innen blau.

Bingsum die Gegend der Cardia, an die Leber (Niere?) angebeftet, fanden
sich vier, 1 . 5-2 mm. lange Individuen eines mit dem Distoma glauci 1 wenig-
stens ganz nabe verwandten Tbieres.

Man kennt jetzt eine kleine Beihe von Chromodoriden (Chr. runcinata, pan-
tbarella, sannio (Fig. 15), picturata, camoena, elegans (Fig. 16), glauca, cali-
forniensis (Fig. 14), Marenzelleri, gonatopbora, sycilla (Fig. 13)), mit eigen-
tbiimlicben blasenartiyen Driisenbildungen am Mantelgebrdme, wozu jetzt auch
die bier untersucbte Form gehort. — Sie scbeint von den scbon bekannten
Cbromodoriden specifiscb verscbieden.

PHLEGMODORIS, Bgh.

R. Bergh, Malacolog. Unters., Heft XIII., 1878, pp. 593-597.

Corpus molle quasi subgelatinosum, dorso tuberculoso. Tentacula pro ma-
jore parte affixa, applanata. Brancbia e foliolis tripinnatis paucis formata.
Podarium sat latum, sulco marginali anteriori non profundo, labio superiore
capite affixo.

Armatura labialis nulla. Radula rhacbide nuda, pleuris multidentatis ;
dentes intimi forma simpliciori, reliqui bamati. — Penis inermis.

Die Phlegmodoriden sind von weicber Korperbescbaffenheit, der Biicken mit
Knoten und Knotchen bedeckt. Die Tentakel etwas applanirt, zum grossten
Theile angeheftet. Die (retractile) Kieme aus wenigen (5) tripinnaten Federn

1 Vgl. meinen : Report on the Nudibranchiata. Challenger Exped., Zool., X.,
1884, p. 18, PI. X., Figs. 5-17.

o

MUSEUM OF COMPARATIVE ZOOLOGY. 169

^ebildet. Der Fuss ziendich breit, mit nicht tiefer vorderer Kandfurche, die
obere Lippe derselben an die Seiten des Kopfes angebeftet. — Keine Lippen-
platte. Die Raspel obne Mittelzahnplatten ; die Seitenzahnplatten zierulich
zablreicb, die innersten von einfacberer Form, die anderen hakenformig. —
Der Penis unbevvaffnet.

Die Pblegmodoriden gehoren den tropiscben, hauptsachlich den indischen
Meeresgegenden.

1. Phi. mephitica, Bgh. M.philippin.

2. Phi. areotata (Aid. et Hanc). M. indie.

3. Phi. sponyiosa (Kelaart). M. indie.

4. Phi. ? anceps, Bgh. M. rnexican.

Phlegmod. ? anceps, Bgh., n. sp.

Tafel I. Fig. 30-36, Tafel II. Fig. 6.

Hob. M. atlant. occ.

Von dieser Form lag ein einziges, in Alkobol mittelmassig conservirtes
Individuum vor, an der Long. 89° 16' und Lat. 23° 13' (d. b. im mexicaniscben
Golfe) aus einer Tiefe von 84 Faden getischt.

Die Lcinge des Individuums betrug 10 mm. bei einer Breite bis 5 und einer
Hohe bis 2 mm. ; die Lange des Fusses 7 bei einer Breite bis 2.2 mm. ; die
Breite des Mantelgebrames 2 mm. ; die Hohe der Rbinopborscbeide 0.8, des
Kiemenbiigels 1 mm. — Die Farbe war durchgehends bell schmutzig gelblich,
am Riicken mit dunklen erbabenen Punkten (Hockerchen). Die Consistenz
des Korpers ziemlich weich.

Die Form langlich-oval, abgeplattet, mit breitem und ziemlich diinnem Man-
telgebrame. Der Riicken mit Andeutung von einem medianen und jederseits
einem, der Grenze des eigentlicben Riickens folgenden, lateralen Kamme; der
Biicken iibrigens iiberall mit zerstreuten spitzen Hockerchen bedeckt, die, beson-
ders am Mantelgebriime, durch Auslaufer oft mit einander verbunden waren;
am medianen Kamm so wie an den hohen Rhinophorscheiden (Fig. 20), und
am hohen Kiemenhiigel waren die Hokerchen hoher und dichter stehend,
besonders am Rande von jenen und diesem. Die Keule der Rhinophorien
beilaufig so hocb wie die Rhinophorscbeide, mit etwa 25 diinnen Blattern;
die Kieme aus 5, bis 1.2 mm. hohen, einfach- hier und da doppelt- gefiederten
Blattern gebildet, von denen die 3 vorderen hoher ; die Analpapille niedrig.
Die Unterseite des Mantelgebrames eben. Die Korperseiten ganz niedrig;
die Genitalpapille wie gewohnlich. Der Fuss nicht schmal, vorn gerundet und
mit Randfurche ; die obere Lippe stark vorspringend, in der Mitte ausge-
randet; der Schwanz nicht ganz kurz. Die Tentakel fingerformig.

Das Centralnervensystem abgeplattet ; die cerebro-pleuralen Ganglien ziemlich
rundlich, die Grenze zwischen den zwei Abtheilungen derselben wenig aus-
gepragt; die pedalen Ganglien rundlich, grosser als die pleuralen, ausserhalb
derselben liegend. Die proximalen Riechknoten fast sessil, ziemlich gross;
die einander fast beriihrenden buccalen und die gastro-oesophagalen Ganglien

170 BULLETIN OF THE

wie gewohnlich; die kugelformigen sessilen Ganglia optica kleiner als die
Augen.

Die Augen ziemlich gross, fast sessil, mit reichlichem schwarzem Pigment.
Die Ohrblasen etwas kleiner als die Augen, von beilaufig 0.08 mm. Diam., von
Otokonien gewohnlicher Art strotzend, die eiuen Durchmesser bis 0.009 mm.
erreichten. In den Blattern der Rhinophorien lange, aber nicht stark erhartete,
auf dem Blattrand senkrecbt und schiefstehende Spikel. In der Riickenhaut
6ebr zahlreiche, lange, mehr oder weniger erhartete Spikel, die auch, und zum
Theile biindelvveise, in den Hockerchen vorkommen, hier aber weniger er-
hartet und meistens mit den Spitzen am Scbeitel der (Fig. 6, Fig. 21) Hocker-
chen hervorragend; eben derselben Art war das Verhaltniss an den Rhinophor-
scheiden und am Kiemenhiigel.

Die aussen weisslich, innen gelbliche (Fig. 22) Mundrohre stark, etwa
1.5 mm. lang ; hinten scheinen mehrere driisenartige Korper einzumiinden
(Fig. 22). — Der kraftige Schlundko])/ etwa so lang wie die Mundrohre, hinten
an der Unterseite trat die Raspelscheide als eine dicke Papille hervor; die
kraftige, rundliche, gelblichgraue Lippenscheibe zeigte sich von einer starken
gelben Cuticula iiberzogen. Die Zunge breit und etwas abgeplattet; in der
breiten gelben Raspel 7 Zahnplattenreihen, von denen die erste sehr incom-
plet ; weiter nach hinten 8 entwickelte und zwei jiingere Reihen; die Ge-
sammtzahl derselben somit 17. Die Rhachis ziemlich breit, nackt; von late-
ralen Platten jederseits 17-18 hinten an der Zunge und weiter nach hinten
19-20. Die Zahnplatten horngelb. Die Lange der 4 innersten betrug mei-
stens 0.06-0.08-0.1-0.11 mm.; die Hohe des Hakens der Platten iibrigens bis
0.11 steigend, die der aussersten nur 0.04-0.06 mm. betragend. Die innersten
(Fig. 23, 24) 4 Platten sind wenig gebogen, schlanker, mehr aufrecht ; danach
entwickelt sich schnell die durch die Reihe bleibende Form (Fig. 25), die
allergewohnlichste Hakenform ; die ausserste oder die zwei aussersten Platten
mit verkiirztem Korper, mehr aufrecht stehend (Fig. 26 aa); die ausserste
schlanker als die nachst stehenden.

Die weisslichen Speicheldriisen langgestreckt.

Die Speiserohre beilaufig so lang wie der Schlundkopf, ziemlich weit. Der
1.5 mm. lange, freie Magen und der Darm wie gewohnlich. Die Verdauungs-
hohle leer. — Die hintere Eingeweidemasse (Leber) kurz-kegelformig, vorne
schief abgestutzt, hinten gerundet, schmutzig-weisslich.

Das Pericardium mit dem Herzen wie gewohnlich; ebenso die abgeplatte-
ten, graulich-weisslichen Blutdriisen.

Die ZwitterdrU.se schien den grossten Theil der Leber zu iiberziehen. kaum
etwas heller als diese ; in den Lappchen Massen von Zoospermien. — Die vor-
dere Genitalmasse beilaufig 1.5 mm. lang, etwas zusammengedriickt; die Am-
pulle des Zwitterdriisenganges ziemlich dick, wurstformig, gebogen, ausge-
streckt ein wenig langer als die Genitalmasse, opak gelblichweiss. Der
Samenleiter nicht lang, der kurze Penis schien unbewaffnet. Die Sperma-
totheke kugelformig ; die Spermatocyste sackformig, gebogen, etwas kleiner.
Die den grossten Theil der Genitalmasse bildende Schleimdriise weisslich,
die Eiweissdriise gelblich.

MUSEUM OF COMPARATIVE ZOOLOGY. 171

Ob diese Form nun wirklich zur Gattung Phlegmodoris gehort, ist sehr
zweifelhaft. Diese Thierform zeigt wie die letztere Gattung die inneren
Seitenzahnplatten von einfacherer Form, hat auch eigenthiimliche driisen-
artige Korper hinten am Mundrohre, so wie stark vortretende Rhincphor-
scheiden. Die Kieme ist hier aber nicht tripinnat wie bei den Plegmodo-
riden, und das Vorderende des Fusses scheint von anderer Beschaffenheit.

Fam. DORIDIDjE PHANEROBRANCHIATjE.

NEMBROTHA, Bgh.

R. Bergh, Malacolog. Unters., Heft XI., 1877, pp. 450-461.

R. Bergh, Beitr. zu einer Monogr. d. Polyceraden, II. Verh. d. k. k. zool. bot.
Ges. in Wien, XXX., 1880, pp. 658-663; III. lb., XXXIII., 1883, pp. 164, 165.

Corpus limaciforme, fere laeve ; tentacula breviora, lobiformia ; rhin'opnoria
retractilia clavo perfoliato ; branchia paucifoliata, foliolis bi- vel tripinnatis;
podarium angustius.

Armatura labialis inconspicua vel nulla. Radula sat angusta; rbachis den-
tibus depressis subquadratis vel arcuatis ; pleurae dente laterali majori falci-
formi singulo et dentibus externis depressis compluribus.

Glandula hermaphrodisiaca hepate connata ; prostata discreta nulla; glans
penis armata.

In den Formverhaltnissen stehen diese Thiere den Trevelyanen sehr nahe,
zeigen auch den Korper Limax-artig, eben, und den Fussrand von den Korper-
seiten fast nicht oder nur wenig vortretend. Die Tentakel sind auch kurz,
lappenformig; die Rhinophorien retractil, mit durchblatterter Keule. Die
(nicht retractile) Kieme auch an etwa der Mitte der Lange des Riickens
stehend, aber aus wenigen (3-5) Fedem gebildet. — An der Lippenscheibe keine
Bewaffnung oder eine ganz schwache (N. nigerrima). Die Zungenbewaffnung
gewissermassen an die der Polyceren erinnernd. An der Rhachis kommen
(im Gegensatze zu der nackten Rhachis der Trevelyanen) subquadratische
oder bogenformige, niedergedriickte Mittelzahnplatten vor ; neben der Mittel-
zahnplatte eine grosse unregelmassig sichelibrmige Seitenzahnplatte ; die aus-
seren Platten niedergedriickt, ohne entwickelten Haken. Die Zwitterdriise
ist (ira Gegensatze zu dem Verhaltnisse der Trevelyanen) von der Leber
nicht gesondert. Der Penis ist in gewohnlicher Weise mit Hakenreihen
bewaffnet.

Die Nembrothen sind bisher nur aus den tropischen Meeresgegenden be-
kannt und zwar fast nur aus dem philippinischen und dem Stillen Meere.

172 BULLETIN OF THE

Der kleinen Reihe von Arten wird die untenstehende neue aus dem mexi-
canischen Golfe Linzufiigen sein.

1. N. nigerrima, Bgh. M. philippin., pacific.

2. N. Kubaryana, Bgh. M. pacific.

3. N. gracilis, Bgh. M. philippin.

4. N. cristata, Bgh. M. philippin.

5. N. morosa, Bgh. M. philippin.

6. N. diaphana, Bgh. M. philippin.

7. N. gratiosa, Bgh., n. sp. M. mexican.

8. N. ? Edvcardsi (Angas). M. pacific.

N- gratiosa, Bgh. n. sp.

Tafel II. Fig. 1-5. Tafel III. Fig. 1-4.

Eab. Sinum Mexicanum.

Es fand sich nur em einziges Individuum vor, an der Breite von 24° 26'
und Lange von 83° 16' aus einer Tiefe von beilaufig 36 Faden gefischt.

Das in Alcohol heivahrte Individuum hatte eine Lange von 22 bei einer
Hohe von 6 und einer Dicke von 4 mm., die Hoke der Kieme noch 4 mm.
betragend ; die Hohe der Rhinophorien 2.5, des Schwanzkammes so wie
der Rhinophorkamme 1.5 mm.; die Breite des Fusses 2.5mm. — Die Farbe
des Thieres wird im Leben prachtvoll gewesen sein ; die Grundfarbe des
Korpers war jetzt hell gelblieh, am Riicken wie an den Korperseiten mit
zahlreich zerstreuten, runden und ovalen, griiugrauen und graugriinen Flecken
von einem Diam. von meistens 0.6-0.8 mm. ; die Rhinophorkamme an ihrem
Grunde aussen von einer Linie von ahnlicher Farbe eingefasst, ihr oberer
Rand schwarzblau, ebenso der Stirn ; die Rhinophorien schwarzblau oben,
gelb unten ; der Rand der Becherartigen Tentakel schwarzblau, ebenso der
Scheitel und der Grund der Hocker des Schwanzkammes und des Fussran-
des oben. die Rbachis-Parthien der Kiemenblatter hell gelblieh, das Laub
schwarzblau ; die Fusssohle gelb.

Das Thier war von etwas mehr zusammengedinickter Form und langer als
andere bekannte Nembrothen. Die Tentakel wegen einer sich ihrer Lange
nach erstreckenden Furche fast ohrenformig, am ausseren Ende etwas gelost
(Fig. 2 a). Zwiscben den Tentakeln der rundliche Aussenmund. Oberhalb
des Mundes tritt der ziemlich schmale, im Vorderrande ein wenig ausgekerbte
Stirn etwa 1.5 mm. hervor. Hinter dem Stirne erhebt sich jederseits ein
starker Rhinophorkamm (Fig. 1 a) mit gebogenem, ebenem Rande ; innen am
Grunde des Kammes die rundliche Oeffnung der Rhinophorhohle, der Rand
derselben hinten mit einem vortretenden Zipfel (Fig. 1 c); die Rhinophorien
kurzstielig, ihre Keule mit etwa 35-40 Blattern. Der Riicken schmal, gerun-
det in die Korperseiten ubergehend ; ein wenig vor seiner Mitte stand die
Kieme, von drei doppelt-fiederigen Blattern gebildet, von denen das hin-

MUSEUM OF COMPARATIVE ZOOLOGY. 173

derste an seinem Grunde noch em kleines Blatt trug. Dicht hinter der Kieme
die wenig vortretende Analpapille, an ihrem Grunde rechts die feine Nieren-
pore. Die Mitte des Schwanzes (des hinter der Kieme liegenden Korpertheils)
trug (in einer Lange von 5 mm.) einen Kamm, der sich in mehrere, grossere
und kleinere, zusammengedriickte, oben gerundete Hocker erhebt. Die Kor-
perseiten ziemlich hoch ; die (zusamniengezogene) Genitaloffnung in der Mitte
zwischen dem Hinterrande des Rhinophorkammes und der Kieme. etwas nach
oben liegend. Der Fuss wie gewohnlich schmal ; der Vorderrand mit tiefer
(Fig. 2 b) Furcbe ; das Fussgebrame schmal.

Die Eingeweide schimmerten am Vorderkorper undeutlich (weisslich) durch.
— Das Peritonaeum farblos. Die Eingeweidehohle sich nur bis etwa dicht
hinter der Gegend der Analpapille erstreckend.

Das Centralnervensystem in eine diinne Bindesubstanzhiille eingeschlossen ;
die Ganglien ziemlich dick. Die cerebro-pleuralen Ganglien je ein fast 8-
Zahl-ahnliche Masse bildend ; die beiden Abtheilungen derselben fast gleich-
gross ; die rundlichen, von vorne nach hinten nur ein wenig zusammenge-
driickten, pedalen Ganglien etwas grosser als die pleuralen ; die gemeinschaft-
liche Commissur ziemlich kurz, nur noch ein halbes Mai so lang wie der
Querdurchmesser des pleuralen Ganglions. Die proximalen Riechknoten fast
sessil, zwiebelformig ; die distalen ein wenig grosser, kugelformig. Die buc-
calen Ganglien abgeplattet-rundlich, fast unmittelbar mit einander verbunden,
etwa so gross wie die proximalen Riechknoten ; gastro-oesophagale Ganglien
wurden nicht gesehen.

Die Augen kurzstielig, mit schwarzem Pigment, hellgelblicher Linse. Die
Ohrblasen etwas kleiner, mit runden und ovalen Otokonien gewohnlicher Art
gefiillt. Die Blatter der Keule der Rhinophorien ohne Spikel. In der inter-
stitiellen Bindcsubstanz kamen erhartete Zellen nur sparsam vor.

Die Mundrdhre kurz und weit, an Lange und in Durchmesser 1.5 mm.
messend. — Der Schlundkopf von gewohnlicher Form, 2.6 mm. lang bei einer
Hohe und Breite von beilaufig 2 mm. ; vom hintersten Theil der Unterseite
ragt die Raspelscheide 0.75 mm. hinab ; die Lippenscheibe ziemlich gross, nur
von einer, besonders im Innenmunde und oben, ziemlich starken gelblichen
Cuticula iiberzogen. Die Zunge stark, etwas abgeplattet. In der hell horn-
gelben, in der Randparthie (wegen der Aussenplatten) braungelben Raspel 10
Zahnplattenreihen ; weiter nach hinten fanden sich deren 4 entwickelte und
2 jiingere ; die Gesammtzahl der Reihen somit 16. Die vorderste Reihe war
auf die mediane Platte und die letzte Aussenplatte reducirt. Die Reihen sonst
an jeder Seite der medianen eine laterale und drei Aussenplatten enthaltcnd.
Die medianen und die Aussenplatten stark horngelb, die lateralen fast farblos.
Die Breite der vordersten medianen Platten 0.24, der hintersten 0.29 mm. ;
die Lange der lateralen Platten hinten an der Zunge 0.56, die Lange der Aus-
senplatten von innen nach aussen meistens 0.2-0.18-0.14 mm. Die medianen
Platten (Taf. II. Fig. 3) flach, mehr breit als lang ; der Vorderrand nicht urn-
gebogen, convex, nicht oder kaum in der Mittellinie ausgerandet, mit etwas
vortretendem gerundetem Ecken ; der Hinterrand mit dem Vorderrande parallel,

174 BULLETIN OF THE

etwas diinner als dieser (Fig. 3 a) ; die Seitenrander fast gerade, mit einander
parallel. Die lateralen Flatten (Taf. III. Fig. 1 aa, 2) gross, unregelmassig,
sichelformig oder eigentlich gleichsam unregelmassige, em wenig zusammenge-
bogene, zum Theil am Riicken ausgehohlte, in den Randern theilweise verdickte
und oben kurz-gekluftete (Fig. 1, 2) Blatter bildend; von dem Doppelthaken
der Spitze ist der nntere Theil der kleinste. Von den drei Aussenplatten, die
alle vorne breiter waren, war die innerste fast doppelt so gross wie die folgende,
subquadratisch, mit einem ziemlich starken, nach innen gericbteten Kamm
(Fig. lbb). Die folgende Platte war ziemlich convex (Fig. Ice, Saa), mit
Andeutung einer Langsleiste. Die ausserste Platte (Fig. 1 dd, 3 bb) war auch
convex, nicht halb so gross wie die vorige.

Die gelblichweissen, nicht recht dicken Speicheldrusen begleiteten den iiber
den Schlundkopf verlaufenden Theil der Speiserohre; die Ausfiihrungsgange
kurz.

Die Speiserohre etwa 3.5 mm. lang, vorne weiter, hinten schmaler, sich oben
am Vorderende der hinteren Eingeweidemasse in die Leberhohle (den Magen)
offnend. Der Darm aus der letzteren an der linken Seite der Cardia aus-
gehend; in seinem Verlaufe erst links, dann quer, dann rechts und nach
hinten gehend, mehrere grosse Biegungen machend; ansgestreckt beilaufig
16mm. messend bei einem Durchmesser von 1-1.5 mm., in seiner ganzen
Lange (wegen seines Inhalts) kalkweiss. Der Inhalt des Darm.es und der
weiten Leberhohle war thierische Masse, theilweise von Bryozoen herriihrend,
und parenchymatose-pflanzliche.

Die hintere Eingeweidemasse (Leber) 11 mm. lang bei einer Hohe und
Breite von 4; sie war fast cylindrisch, hinten gerundet, vorne schief nach unten
und vorne abgestutzt; ihre Farbe war aussen schwarzlichgrau, dieselbe aber
zum grossten Theil von der Zwitterdriise verdeckt; die Substanz der Leber
und die Wand der weiten Hohle schwarz oder schwarzbraun.

Das Herz wie gewohnlich. Die Blutdriise gelblichweiss, queroval, ziemlich
abgeplattet, hinter dem Centralnervensystem liegend und etwa so breit wie
dieses. — Die Niere wie gewohnlich, der Nierentrichter birnfdrmig, etwa
0.55 mm. lang, mit etwa 10 Hauptfalten.

Die gelbliche Zwitterdriise mit einem fast einfachen Lager von dicht-
stehenden meistens an einander stossenden Lappchen (Taf. II. Fig. 4), die
Leber fast iiberall uberziehend. In den Ovarialfollikeln der Lappchen grosse
Eierzellen, in der nicht sehr abgeplatteten Testicularplatte keine reife Zoo-
spermien. Der diinne weissliche Zwitterdriisengang frei an der rechten Seite
der Cardia vortretend und langs der Speiserohre an die vordere Genital-
masse verlaufend. Diese letztere, etwa 2.5 mm. lang bei einer Breite und
Dicke von 2.2 mm.; die Ausfiihrungsgange noch 1.6 mm. vortretend; das
Vorderende der Masse wird von der Schlinge der Ampulle des Zwitterdriisen-
ganges gebildet ; hinten an der oberen Seite liegt die grosse Samenblase, und
an der ausseren (rechten) Seite schlangelte sich der Samenleiter. Die er-
wahnte Ampulle wurstformig, stark zusammengebogen, ausgestreckt 3 mm.
lang bei einem Durchmesser von 0.8. Der stark geschlangelte prostatische

MUSEUM OF COMPARATIVE ZOOLOGY. 175

Theil des Samenleiters etwa 5 mm. lang ; der muskulbse beilaufig 4 mm. lang,
eine grosse Schlinge bildend, unten endigte derselbe als eine kleine Glans am
Boden des etwas dickeren, etwa 0.7 mm. langen Pracputiums. In fast dem
unteren Viertel des musculdsen Samenleiters tindet sich eine sich bis in die
Glans fortsetzende Bewaffnung. Dieselbe besteht aus etwa 10-12 Quincunx-
Eeihen von kleinen gelblichen Haken, die eine Hohe bis zn beilaufig 0.02 mm.
erreichen (Fig. 5). Die Spermatothcke (Taf. III. Fig. 4 a) kugelfbrmig, von
etwa 1 mm. Durchmesser. Die (von dem Samenleiter verdeckte Spermato-
cyste ein wenig kleiner, auch (Fig. 4 d) kugelfbrmig; ihr Ausfiihrungsgang
etwas langer als die Blase, in den uterinen Ausfuhrungsgang der Spermato-
theke (Fig. 4 c) iibergebend. Die Schleim- und Eiweissdriise (wie alle die
iibrigen der vorderen Genitalmasse gehbrenden Organe) weiss und gelblich-
weiss. Das Vestibulum genitale mit starken Langefalten.

Diese unzweifelhaft neue Form der Gattung Nembrotha scheint der N. dia-
phana am Nachsten zu stehen, unterscheidet sich aber schon im Aeusseren
deutlich genug durch die starken Rhinophorkamme und durch die ganz ver-
schiedene Farbenzeichnung, noch dazu durch die etwas verschiedene Beschaf-
fenheit der Raspel.

Fam. PHYLLIDIAD.E.
PHYLLIDIOPSIS, Bgh.

R. Bejgh, Neue Beitr. zur Kenntn. d. Phyllidiaden. Verh. d. k. k. zool. bot. Ges.

in Wien, XXV., 1875, pp. 661, 670-673, Taf. XVI. Fig. 11-15.
R. Bergh, Malacolog. Unters. (Semper, Philipp. II. ii.), Heft XVI., 2, 1889, pp.

859, 866-867, Taf. LXXXIV. Fig. 23-27.

Dorsum ut in Phyllidiis propriis. Apertura aualis dorsalis.
Tubus oralis ut in Doriopsidibus ; glandula ptyalina discreta (?).

Die Phyllidiopsen bilden gewissermassen ein interessantes Zwischenglied
zwischen den Phyllidien und den Doriopsen. Im Ganzen sehen sie den achten
Phyllidien ahnlich aus und haben dieselbe Lage der Analbtfnung. Die Ten-
takel sind sehr klein und wie bei den Doriopsen ihrer ganzen Lange nach
angeheftet. Die Mundrbhre ist wie bei den Doriopsen ; es scheint, auch wie
bei den Doriopsen, eine gesonderte Mundspeicheldriise (Gland, ptyalina) vor-
zukommen.

Die Gruppe ist, wie andere Phyllidiaden, nur aus den tropischen Meeres-
gegenden bekannt, und umfasst bisher nur die unterstehenden Arten.

1. Ph. cardinalis, Bgh. M. pacific. (Ins. Tonga).

2. Ph. striata, Bgh. M. africano-indic. (Maurit.).

3. Ph. papilhgera, Bgh., n. sp. M. mexicanum.

176 BULLETIN OF THE

Phyllidiopsis papilligera, Bgh., n. sp.

Tafel II. Fig. 7-14.

Hob. M. mexicanum.

Von der Form lag nnr ein einziges Individuum vor, aus einer Tiefe von
101 Faden an 25° 33' Br. und 84° 21' L. (d. h. im mexicanischen Golfe) hinauf
gefischt.

Das in Alkohol bewahrte Individuum hatte eine Liinge von 12 bei einer
Breite bis 11 und einer Hohe bis 4.5 mm.; die Breite des Mantelgebrames
3 mm., die Hbhe der (zuriickgezogenen) Rhinophorien 1.5 mm.; die Lange des
Fusses 7.5 bei einer Breite bis 6 mm. — Die Grundfarbe des Riickens weiss-
lich, an derselben viele runde und ovale, grosse und kleine, sammetschwarze
(bis 2.5 mm. breiten) Flecken, die meistens Papillen tragen, welche theil-
weise auch schwarz sind ; an der weisslichen Unterseite des Mantelgebrames
schimmerten die schwarzen Riickenflecke durch ; die iibrige Unterseite (gelb-
lich-) weissbch. Die Rhinophorien und der Aussenmund gelblich.

Die Form fast rundlich, etwas gewolbt (Fig. 7), mit breitem diinnem Mantel-
gebrame. Die Consistenz des Thieres nicht hart, nicht recht steif. Der Riicken
eben, aber mit ziemlich zahlreichen, bis etwa 1.6 mm. hohen, zusammenge-
driickten, mehr oder weniger, besonders an der einen (meistens vorderen)
Seite, schwarzfarbigen Papillen bedeckt. Die Rhinophordffnungen (Fig. 7 a)
ziemlich weit von einander liegend, die starke Rhinophorkeule mit etwa 20-25
Blattern. Die Analpore median hinten am Riicken (Fig. lb). Der innerste
Theil des Mantelgebrames ist dicht mit quergehenden, meistens an der Mitte
hdheren, bis 1.5 langen diinnen Blattern bedeckt ; hinten begegnen sich die
Blatterreihen iiber den Schwanzgrund, vorn erstrecken sie sich bis an den Aus-
senmund; die Anzahl der Blatter jederseits 45-50. Keine Spur von Tentakeln
wurde gesehen; der Aussenmund land sich als eine starke durchbohrte Papille
vor dem Vorderrande des Fusses. Die Genitalpbre an gewbhnlicher Stelle
der niedrigen (rechten) Korperseite. Der Fuss gross, breit, vorne abgestutzt-
gerundet und mit Randfurche, das Fussgebrame nicht schmal, der Schwanz
nicht kurz.

Das Centralnervensystem (Fig. 9) zeigte die cerebro-pleuralen Ganglien nie-
renformig, schrage gegen einander liegend, nach vorne convergirend (Fig.
9ab); die pedalen Ganglien an der Unterseite der pleuralen liegend, grosser
als diese, rundlich (Fig. 9 cc) ; die gemeinschaftliche Commissur doppelt, diinn
(Fig. 9(7). Die proximalen Riechknoten fast sessil, zwiebelfbrmig (Fig. 9);
die distalen kugell'ormig. Die buccalen Ganglien (Fig. 13 c) an gewbhnlicher
Stelle, rundlich, einander beriihrend.

Die Augen fast sessil, von 0.1 mm. Diam., mit reichlichem schwarzem Pig-
ment (Fig. 9). Die Ohrblasen weit von den vorigen an der Unterseite (Fig. 9)
der Gehirnknoten liegend, von beilaufig 0.06 mm. Diam. ; etwa 50-100 ovalen
Otokonien von einem Durchmesser bis 0.013 mm. enthaltend, unter denen ein
grbsserer rundlicher (Fig. 12). In den Blattern der Keule der Rhinophorien,

MUSEUM OF COMPARATIVE ZOOLOGY. 177

wie gewohnlich, diinne, mehr oder weniger erhartete, kiirzere und langere
Spikel, die letzteren zum grossen Theile auf dem freien Rande senkrecht
stehend (Fig. 10). In der Haut des Riickens eine Unmasse von grosseren
und kleineren Spikeln und Biindel von solchen, welche aueh unter der Loupe
schon durchschimmerten (Fig. 7); im Mantelgebrame waren dieselben zum
grossen Theile senkrecht und schrag (Fig. 11) gegen den Rand geordnet; sonst
lagen sie mehr ungeordnet. Die Spikel waren von den gewohnlichen bei
diesen Thieren vorkommenden Formverhaltnissen (Fig. 10, 11), meistens stark
erhartet, oft glasartig; von einem Durchmesser bis 0.16 mm., von sehr wech-
selnder Lange, die oft bis iiber 0.4 mm. stieg. Biiudel von ahnlicben Spikel
stiegen in die Papillen bis an ihre Spitze auf (Fig. 8). In der interstitiellen
Bindesubstanz kamen iiberall Massen von grosseren und kleineren meistens
stark erharteten Spikel vor, so wie verkalkte Klumpen und Kugeln.

Durch den Aussenmund war das Ende des Mundrohres etwas hervorge-
stiilpt; unter jenein fand sich die Oeffnung der Mundrbhrendriise (Fig. 13 a).
Die gelblichweisse Mundrohre (Fig. 13 a, 14 a) weit, nieht kurz, 2 mm. lang,
hinten mit (Fig. 13) einer kreisartigen Einschniirung ; die Innenseite (Fig.
14 a) mit Langsfalten ; in das vertiefte Hinterende derselben senkt sich der
gelbliche Schlundkopf, der am Boden der Mundrohrenhbhle stark vorspringt
(Fig. 14 b). Dieser Schlundkopf (Fig. 13 6) von gewohnlicher Form, fast
cylindrisch, von starker gelblicher Cuticula an der Innenseite iiberzogen, etwa
2 mm. lang; am etWas engeren Hinterende des Schlundkopfes (Fig. 13 c) die
buccalen Ganglien. Hinter den letzteren finden sich (Fig. 13 d) die gewohn-
lichen, hier fast kugelformigen eigentlichen (hinteren) Speicheldriisen (Gl.
salivales) (Fig. 13 d). Es kommt aber jederseits (?) noch eine langliche, et-
was lappige, weissliche vordere Speicheldriise (Gl. saliv. access.) vor, (Fig. 13/),
die neben dem Schlundkopf das Hinterende der Mundrohre durchbohrt ; sein
Hinterende geht in einen bindegewebigen Strang iiber. Unter dem Schlund-
kopf liegt die lappige, weissliche Mundrbhrendriise (Gl. ptyalina), welche in
einen starken Ausfiihrungsgang ubergeht, die sich hier nicht in die Mund-
rohre, sondern unmittelbar unter dem Aussenmunde offnete (Fig 13 gg).

Das Hinterende des Schlundkopfs geht etwas enger in die gestreckt-schlauch-
fbrmige Speiserdhre (Fig. 13 e) iiber, welche ein wenig kiirzer als der Schlund-
kopf ist und die obere Seite der hinteren Eingeweidemasse durchbohrt. Die
in dieser letzteren eingeschlossene Magenhbhle nicht weit. Der Darm die
Eingeweidemasse am Anfang des letzten Drittels durchbrechend und in ge-
wohnlicher Weise verlaufend. — Die Verdauungshohle war leer.

Die hintere Eingeweidemasse (Leber) 5.5 mm. lang bei einer Breite von
4 und einer Hbhe von 3 mm., vorne schrag abgestutzt, hinten gerundet ; die
Substanz gelblichweiss.

Das querliegende Pericardium ziemlich gross; das Herz wie gewohnlich.
Die Blutdriise gerundet-viereckig, graulichweiss. Die Niere in gewohnlicher
Weise die obere Seite der hinteren Eingeweidemasse iiberziehend ; die Urin-
kammer wie gewohnlich.

Die Zwitterdriise durch mehr gelbliche Farbe von der Leber hier und da

vol. xix. — no 3 12

178 BULLETIN OF THE

unterscheidbar ; in den Lappchen Eierzellen und reife Zoospermien. — Die
vordere Genitalmasse gerundet-viereckig, beilaufig 3 mm. lang. Die weissliche
Ampulle des Zwitterdriissenganges vurstfbnnig gebogen. Die Samenblasen
weisslicb; die Spermatotheke kugelfdrmig, die Spermatocyste eifbrmig. Der
Samenleiter nicht lang; das Dasein einer Penis-Bewaffnung konnte nicb nacb-
gewiesen werden. Die Schleimdriise weisslich, die Eiweissdriise mehr gelb.

Bisher war keine am Riicken Papillen-tragende Form von Phyllidiaden
bekannt worden. Diese nimmt in dieser Beziebung eine abnliche Stellung
unter den Pbyllidiaden wie die Ecbinodoris 1 unter den Doriden ein.

1 R. Bergh, Neue Nacktschnecken der Siidsee, II. Journ. d. Mus. Godeffroy,
Heft VI., 1874, pp. 19-22, Taf. III. Fig. 4-20.

MUSEUM OF COMPARATIVE ZOOLOGY. 179

TAFEL-ERKLARUNG.

TAFEL I.

Tethys leporina (L.).

Fig. 1. Verdauungssystem ; a das (an der Unterseite gekluftete) Mundrohr;
b vorderer, c hinterer Theil der Speiserohre ; dd die in den ganz rudi-
mentaren Schlundkopf einmiiudenden Speicheldriisen, zwischen den
Hinterendeu derselben die buccalen Ganglien ; e Hinterende des (ersten)
Magens, / zweiter Magen, g Darm ; h Zweig der rechten Nebenleber
in das Rhinophor, i in die vorderste rechte Papille; H linke Nebenleber
mit ihren Zweigen, m Hauptausfiihrungsgang der Hauptleber.

Fig. 2. Speicheldriise (linke), mit Cam. gezeichnet (Vergr. 55).

Fig. 3. Otocyste, mit Cam. gezeichnet (Vergr. 350) ; a StieL

Chromodoris punctilucens, Bgh.

Fig. 4. Lippenscheibe mit Mundoffuung und Lippenplatte.

Fig. 5. Stuck der Lippenplatte.

Fig. 6. Grosste Elemente derselben.

Fig. 7. Von der Rhachisparthie der Raspel ; a rhaehidiale Verdickung, bb innerste

Seitenzahnplatte.
Fig. 8. Zahnplatte aus dem inneren Drittel einer Reihe.
Fig. 9. Eine der grossten Platten.

Fig. 10. Aeusserer Theil zweier Zahnplattenreihen ; a ausserste Platte der Reihen.
Fig. 5-10 mit Cam. gezeichnet (Vergr. 350).

Chromodoris scabriuscula, Bgh.

Fig. 1 1 . Elemente der Lippenplatte, von vorne.

Fig. 12. Aehnliche, von der Seite.

Fig. 13. Stuck der Raspel; a mediane Platte.

Fig. 11-13 mit Cam. gezeichnet (Vergr. 350).
Fig. 14. Mediane Platte, von oben.

Fig. 15, 16. Zahnplatten vom inneren Drittel einer Reihe.
Fig. 17. Eine der grossten Platten.

180 BULLETIN OF THE

Fig. 18. Aeusserste Platte einer Reihe.

Fig. 14-18 mit Cam. gezeichnet (Vergr. 750).
Fig. 19. a muskuloser Theil des Sanungangs, 6 Praeputium mit zuriickgezogener
Glans; mit Cam. gezeichnet (Vergr. 55).

Phlegmodoris? anceps, Bgh.

Fig. 20. Rhinophorscheide, a Grund; mit Cam. gezeichnet (Vergr. 55).
Fig. 21. Hockerchen des Riickens, mit Cam. gezeichnet (Vergr. 200).
Fig. 22. Mundrohre, aa Retractoren, b Driisen am Hinterrande des Mundrohres.
Fig. 23. Innerster Theil einer Zahnplattenreihe; a erste Platte.
Fig. 24. Aehnlicher von zwei Reihen, ab erste Platte derselben.
Fig. 25. Eine der grossten Flatten.

Fig. 26. Aeusserster Theil zweier Zahnplattenreihen mit 8 und 9 Platten, aa
ausserste.
Fig. 23-26 mit Cam. gezeichnet (Vergr. 350).

TAFEL II.

Nembrotha gratiosa, Bgh.

Fig. 1. Rhinophorkamm, in b den Riicken iibergehend, c Rhinophoroffnung.

Fig. 2. a Tentakel, b Vorderrand des Fusses.

Fig. 3. Mediane Zahnplatte, mit Cam. gezeichnet (Vergr. 200), a Hinterrand.

Fig. 4. L'appchen der Zwitterdriise.

Fig. 5. Haken der Penis-Bewaffnung, mit Cam. gezeichnet (Vergr. 750).

Phlegmodoris ? anceps, Bgh.

Fig. 6. Stuck der Ruckenhaut, vom Rande gesehen ; mit Cam. gezeichnet (Vergr,.
200).

Phyllidiopsis papilligera, Bgh.

Fig. 7. Das Thier, von der Riickenseite ; a Gegend der Rhinophor-Oeffnungen,

6 Gegend der Analpore.
Eine der kleineren Riickenpapillen.
Das Centralnervensystem, mit Cam. gezeichnet (Vergr. 55); ab cerebro-

pleurale, cc pedale Ganglien ; d gemeinschaftliche Commissur.
Rand eines Rhinophor-Blattes, mit Cam. gezeichnet (Vergr. 350).
Vom Mantelrande; mit Cam. gezeichnet (Vergr. 55).
Otocyste, mit Cam. gezeichnet (Vergr. 350).
a Mundrohre, 6 Schlundkopf, c buccale Ganglien, d Speicheldriisen (61.

salivales), c Speiserohre, / Accessorische Speicheldriisen (Gl.

access.), <7<7 Ausfiihrungsgang der Mundrohrendriise (Gl. ptyalina).
Fig. 14. a geoflnete Mundrohre, b Vorderende des Schlundkopfs.

Fig.

8.

Fig.

9.

Fig.

10.

Fig.

11.

Fig.

12.

Fig.

13.

MUSEUM OF COMPARATIVE ZOOLOGY. 181

TAFEL III.

Nembrotha gratiosa, Bgh.

Fig. 1. Zwei Reihen von pleuralen Zalinplatten (linker Seite) von oben; aaa
laterale Flatten ; bb innerste, cc mittlere, dd ausserste Aussenplatte.

Fig. 2. Laterale Platte von der Ruckenseite.

Fig. 3. Aeusserster Theil dreier Zahnplattenreihen mit den je zwei aussersten
Aussenplatten.
Fig. 1-3 mit Cam. gezeichnet (Vergr. 200).

Fig. 4. a Spermatotheke, b vaginaler und c uteriner Gang; d Spermatocyste,
e Diverticulum des Ausfiihrungsganges der Spermatocyste.

Chromodoris sy cilia, Bgh.

Elemente der Lippenplatte.

Zwei Zahuplatten aus der Mitte einer Reihe der Zunge.
Zahnplatte vom inneren Zehntel einer Reihe.
Zwanzigste Zahnplatte von aussen ab.
Eine der innersteu Seitenplatten.
Vierte Zahnplatte, von aussen ab.
Dritte Zahnplatte, von aussen ab.

Die drei aussersten Zahnplatten, von innen ; a ausserste.
Fig. 5-12 mit Cam. gezeichnet (Vergr. 350).
Fig. 13. Hinterende des Korpers, von oben (Mantelgebr'ame), mit den weissen
Flecken ; aa Driisenbildungen der Unterseite des Mantelgebrames.

Chromod. Californiensis, Bgh.

(Vgl. R. Bergh, On the Nudibr. Gaster. Moll, of the North-Pacific Ocean.
II., 1880, PI. XIV. Fig. 5. Scientific Results of the Explor. of Alaska,
Vol.1. Art. vi., 2.)
Fig. 14. Hinterende des Mantelrandes, von der Unterseite, mit 6 Driisen beutel ;
a Fuss.

Chromod. sannio, Bgh.

(Vgl. R. Bergh, Malacolog. Uhters. (Semper, Philipp. II. ii.), Heft XVII.,
1890, Taf. LXXXVII. Fig. 1.)
Fig. 15. Hinterende des Mantelrandes, von der Unterseite, mit 4 grossen Driisen-
beuteln ; a Fuss.

Chromod. elegans (Cantr.).

(Vgl. R. Bergh, Untersuch. d. Chromod. elegans und villafranca. Mala-
kozool. Blatter, XXV.. 1878, Taf. I. Fig. 4.)
Fig. 16. Dr'usenbeutel von der Unterseite des Mantelgebrames.

Fig.

5.

Fig.

6,

Fig.

7.

Fig.

8.

Fig.

9.

Fig.

10.

Fig.

11.

Fig.

12

BlttAc. MoZlusoa . Nzidiiraitoiiiata

6\

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f^>a^

# JicryA

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JSlakc Molu-fcii.- Ihn{thr.in</mit<i

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No. 4. — A Third Supplement to the Fifth Volume of the Terres-
trial Air-Breathing Mollusks of the United States and adjacent
Territories. By W. G. Binney.1

As promised in the Second Supplement, the Eastern Province Species
are here given, with addenda to those of the other Provinces. My pur-
pose is to bring the subject down to this date. The " Manual of Amer-
ican Land Shells," published subsequently to Vol. V., must also be used
in connection with the present paper. I have added figures of many
species to replace those of Volume V.

Burlington, New Jersey, January 1, 1890.

SPECIES OF THE NORTHERN REGION.

It must be borne in mind that the Universally Distributed Species are also
found here. They are : —

Patula striatella, Anthony.

Microphysa pygmaea, Drap.

Placed in this genus on account of the similarity of its jaw and lingual
dentition to those of other species of Microphysa. See 2d Suppl., p. 35.

Helicodiscus lineatus, Say.
Vallonia pulehella, Mull.

Pupa muscorum, Linn.

See below, p. 186, for vars. bigranata and Luudstromi.

It may readily be doubted whether this species is not rather confined to the
Northern Region.

1 The Terrestrial Air-Breathing Mollusks of the United States and the adjacent
Territories of North America, described and illustrated by Amos Binney. Edited
by A. A. Gould. Boston, Little and Brown, Vols. I., II., 1851 ; III., 1857. Vol.
IV., by W. G. Binney, New York, B. Westermann, 1859 (from Boston Journ. Nat.
Hist.). Vol. V., forming Bull. Mus. Comp. Zool., Vol. IV., 1878. Supplement to
same, in same, Vol. IX. No. 8, 1883. Second Supplement, in same, Vol. XIII.
No. 2, 1886.

VOL. XIX.— NO. 4.

184 BULLETIN OF THE

Zonites nitidus, Mull.
arboreus, Say.

indentatus, Sat.
See Suppl., p. 139.

Zonites minusculus, Binn.

Dall thus describes a var. Alachuana (Pr. U. S. Nat. Mus., 1855, 270): —

A form of it which, at first sight, looks different from minuscula is rather larger
than usual, and above shows no differences. On the base in the type the junction
of the inner lip with the body whorl takes place, following the course of the whorl,
inward from the middle line of the base of the whorl and generally about the inner
third. This gives a peculiarly thimble-shaped umbilicus. In the variety under
consideration, the above mentioned junction takes place outside of the middle line,
or even at the outer third, while the aperture is a little dilated. The result of this
is to show a much larger portion of the base of the penultimate whorl, and to alter
the facies of the umbilicus. For this form, found in Alachua County, Florida, I
would suggest the varietal name Alachuana.

Zonites viridulus, Mke.
milium, Morse.
fulvus, Drap.

These will not be repeated in the lists of the various Regions into which the
Province may be divided. (See Vol. V., p. 17.)

The following are Northern Region Species: —

Vitrina limpida, Gld.

Angelicae, Beck.

Vitrina exilis, More let.

The distinction between the Eastern, Central, and Pacific Provinces not being
marked in these high latitudes, this species is given here. It might, perhaps,
with Patula pauper and Pupa borealis, rather be considered a species of the
Pacific Province.

Zonites Fabricii, Beck.

Binneyanus, Morse.
ferreus, Morse.

Zonites exiguus, Stimfson.

Plate III. Fig- 4.

The figures are copies of original drawings of Dr. Stimpson.

Zonites multidentatus, Binney.

See Suppl., p. 144.

Acanthinula harpa, Say.
Patula asteriscus, Morse.

MUSEUM OF COMPARATIVE ZOOLOGY. 185

Patula pauper, Gould.

See remarks under Vitrina exilis, above.

Pupa Blandi, Morse.

borealis, Mokelet.

See remark under Vitrina exilis.

The figure was drawn by me from a specimen collected at the
original locality.

Pupa decora, Gould.

-it.. •• »*•• Pupa borealis,

HOPPII, MOLLER. enlarged.

Vertigo Gouldi, Binney.

Bollesiana, Morse.

A variety Arthuri, from Dakota, is mentioned by Von Martens, Gesell. Nat.
Freunde zu Berlin, 21 Nov., 1882, p. 140.
Very near, if not identical with, V. milium.

Vertigo simplex, Gould.

ventricosa, Morse.

Very near, if not identical with, V. Gouldi.

Ferussacia subcylindrica, Linn.

In the mountains of McDonnel Co., North Carolina, a colony of this species
was found by Mr. Hemphill. He found no colony of Vitrina, which might
be expected to exist at those high elevations.

Succinea Haydeni, W. G. B
Verrilli, Bland.
Gronlandica, Beck.
Higginsi, Bland.
Totteniana, Lea.

Dr. Westerlund, in the " Land- och Sottvatten-Mollusker " of the Vega Ex-
pedition, quoted in the Manual of American Land Shells, pp. 473, 474, also
catalogues from Arctic America the following species: —

Limax hyperboreus, Westerlund. (See below, p. 205.)
Pupa arctica, Wall.

columella, Benz.
Succinea chrysis, Westerlund. (See p. 186.)

turgida, Westerlund.

annexa, Westerlund. (See p. 186.)
Vallonia Asiatica, Nevin.
Pupa edentula, Drap. ?

signata, Ms.
Vertigo Bollesiana, var. Arthuri.

186 BULLETIN OF THE

Pupa muscorum, var. bigranata, Ross.

muscorum, var. Lundstromi, Westerlund.
columella, Benz., var. Gredleri, Clessin.
Krausseana, Reinh.

Of the above, descriptions and figures are given of two only, Succinea chrysis
and S. annexa, which are copied here.

Succinea chrysis, Westerlund.
(Figures copied on my Plate I. Fig. 14.)
Testa oblongo-ovata, solida, irregulariter transversim striata vel ssepe costu-
lato-plicata, colore varia, saepissime spira pallidiore, apice rubro, anfractu ultimo
antice rotuntiore, subviolaceo-rufescente, postice pallidiore, ubique strigis trans-
versis numerosis albidis; spira elevata, acuta, anfr. 3^, convexi, ultimus deorsum
lente attenuatus, penultimus subtus tumidulus, antepenultimus transversalis,
extus depressus, sutura forte excisa, anfr. ultimo minutissimo; sutura perim-
pressa, apertura ovata, intus aureo-micans, pariete arcuatula, obliqua; peristoma
obscure marginatum, marginibus sequaliter arcuatis (exteriore superne ad inser-
tionem forte curvato), in pariete callo tenuissimo albido conjunctis.
Long. 11 J, diam. 7£, ap. "t\ mm. 1., 5 mm. d. ; long. 13, diam. 7-^, ap.
long. 9, diam. 7^ mm.; long. 10, diam. 6, ap. long. C^, diam. 5 mm.
Asia : America, Port Clarence, Alaska.

I figure also a specimen from St. Michael's, Alaska (Dall), which
chrysis. has usually been referred to a form of S. lineata.

Succinea annexa.
(Figures copied on my Plate I. Fig. 15.)

Testa elongato-ovata, fragilis, intus rugas incrementales fuscas (in spec, max.)
validas et extus abruptas dense striata, anfr. penultimo dense distincte spira-
liter lineata, anfr. ultimo transversim irregulariter alternatim rufo- et albido-
strigata ; sutura impressa ; spira exserta, apice mamillata ; afr. 4, ultimus
convexus, penultimus tumidus, antepenultimus altus, exitus convexus, sutura
tenui a prsecedente sejunctus, summus (subtus visas) globosus; apertura ovata,
pariete obliqua, columella arcuata, marginibus linea tenui alba junctis. Long.
11, diam. 8, apert. long. 8, diam. 6 mm.; long. 10, diam. 6^, apert. long. 6,
diam. 4^ mm.

Fort Clarence, Alaska.

INTERIOR REGION SPECIES.

Macrocylis concava, Say.
Zonites capnodes, W. G. B.

fuliginosus, Griffith.

friabilis, W. G. B.

MUSEUM OF COMPARATIVE ZOOLOGY. 187

Zonites laevigatus, Pfeiffer.
Rugeli, W. G. B.

See Suppl., p. 138.

Zonites demissus, Binnet.

The variety acerrus has been found near Fort Gibson, Indian Territory,
by Mr. Simpson.

Zonites ligerus, Sat.

A variety Stonei is thus described by Mr. Pilsbry : " From Mr. Witmer
Stone I have received a form of Z. ligerus differing from the type in having a
concave, broadly excavated base, with comparatively wide umbilicus, collected
by him in New Castle Co., Del. The axis in the type is barely perforated ;
but in this form it is a millimeter or more wide, and the base around it
broadly concave." (Nautilus, III. 4, p. 46, Aug., 1889.)

Zonites intertextus, Binnet.
subplanus, Binnet.
See Suppl., p. 139.

Zonites inornatus, Sat.

sculptilis, Bland.
Elliotti, Redfield.
limatulus, Ward.
capsella, Gould.
Lawse, W. G. B.

See Suppl., p. 142, Plate II., Fig. E. The name is suggested for the shell
figured by me in Vol. V. (Fig. 44) as Z. placentula.

Zonites placentula, Shuttleworth.
See Suppl., p. 142.

Zonites Wheatleyi, Bland.
See Suppl., p. 141. Clingham's Peak, N. C. (Hemphill).
Zonites petrophilus, Bland.

Habersham Co., Ga. ; Clarkesville, N. C. (Hemphill). See Suppl., p. 140.

Zonites Sterkii, Dall.

Shell minute, thin, yellowish translucent, brilliant, lines of growth hardly
noticeable, spire depressed, four-whorled ; whorls rounded,
base flattened, somewhat excavated about the centre, which is
imperforate; aperture wide, hardly oblique, not very high,
semilunate, sharp-edged, the upper part of the columella
slightly reflected ; upper surface of the whorls roundish,
though the spire as a whole is depressed. Greater diam. 1.1, Zonites sterkii,

, , enlarged,

height 0.52 mm.

188 BULLETIN OF THE

New Philadelphia, Ohio. Collected on a grassy slope, inclining to the north-
ward, and covered with grass, moss, and small bushes, and so far has not been
found elsewhere. Clearly not young of a Pwpilla or Zonites. It is probably
one of the smallest species known, and remarkable for its imperforate umbilicus.

The above forms a portion of the description by Dall of Hyalina Sterkii,
from Proc. U. S. Nat. Mus., XI., p. 214, Figs. 1, 2, 3, 1888. The figure given
by me is drawn from an authentic specimen.

Zonites gularis, Sat.

suppressus, Sat.
CUSpidatus, Lewis.
See Suppl., p. 143.

Miss Law thus wrote from Philadelphia, Tenn., of this species : " Unlike
gularis it seems to be a rare shell, and I find it only by scraping off the
surface of the ground in the vicinity of damp mossy rocks. Its habits are
more like placentula than gularis. Neither Miss Clara Bacome nor I ever mis-
take one for a gularis, even before picking it up ; the thickened yellow splotch
near the lip, and the thinner spot behind, showing the dark animal through it,
as well as its more globular form, particularly on the base, make it look very
different when alive."

Zonites lasmodon, Phillips.

Plate III. Fig. 5.

Enlarged drawings by Miss Lawson are given of this species.

Zonites macilentus, Shuttl.
See Suppl., p. 143.

Zonites signiflcans, Bland.
See Suppl., p. 144.

Zonites Andrewsi, W. G. B.
See Suppl., p. 144.

Zonites internus, Sat.
Vitrinizonites latissimus, Lewis.

See Suppl., p. 145 ; for other localities, see Man. of Am. Land Sh., p. 231,
Also in Washington Co., N. C, and in Watauga Co. at Banner's Elk (Hemp-
hill).

Limax campestris, Binnbt.

Limax montanus, castaneus, occidentalis, hyperboreus, and Hemphilli are
probably identical with this.

Tebennophorus Caroliniensis, Bosc.
Tebennophorus dorsalis, Binnet.
Tebennophorus Wetherbyi, W. G. B.
See Plate VI. Fig. F.

MUSEUM OF COMPARATIVE ZOOLOGY. 189

Te^nnophorus Hemphilli, W. G. B.

Plate VI. Fig. H.

See Man. of Amer. Land tih., p. 247.

The animal is long, narrow, cylindrical, with pointed tail. Its color is
black. The jaw is strongly arched, with median projection, and four or five
ribs conver»in" to the centre, all crowded on the middle third, the outer thirds
beincr ribless. The lingual membrane has 24-14-1-14-24 teeth, all of same
types as figured by Morse for that of T. dorsalis. Length of largest individ-
ual contracted in spirit 25 mm.

The penis sac is long, cylindrical, receiving retractor muscle and vas deferens

at its summit.

Patula solitaria, Sat.
alternata, Sat.
Cumberlandiana, Lea.
perspectiva, Sat.

Bryanti, Harper.

See Suppl., p. 147.

Helicodiscus flmbriatus, Wetherbt.

See Suppl., p. 148.

A curious form, wanting the epidermal fringe and most of the revolving
ridges, was found in great numbers near Fort Gibson, Indian Territory, by Mr.
C. T. Simpson. The same form has been found by Mr. Hemphill on Salmon
River, Idaho. He proposes for it the name Salmonacea.

Strobila labyrinthica, Sat.
A form from Venezuela, without the costse, is noticed by Dall as var. Morsel
(U. S. Nat. Mus. Proc, 1855, p. 263).

Polygyra leporina, Go old.
Hazard!, Bland.
Troostiana, Lea.
fastigans, Sat.
Stenotrema spinosum, Lea.
labiosum, Gould.
Edgarianum, Lea.
Edvardsi, Bland.
barbigerum, Redfield.
stenotremum, Ferussac.
hirsutum, Sat.
A widely separated locality is the bank of the Yaqui River, near Guaymas

(Palmer).

Stenotrema maxillatum, Gould.
monodon, Rackett.
Triodopsis palliata, Sat.

190 BULLETIN OF THE

Triodopsis obstricta, Say.
appressa, Say.

It is quoted by Von Martens from the banks of the Columbia River, but
from drawings and description of the single specimen found by Kraus, kindly
sent me by Dr. Von Martens, it appears that the species was confounded with
llattened forms of Mullaniov devius.

Triodopsis inflecta, Say.

A depauperated form of this species is about being described and figured as
T. edeutula by Mr. F. A. Sampson.

Triodopsis Rugeli, Shuttlewoktii.
tridentata, Say.
The deformed specimen figured is one of appressa, not of this species.

Triodopsis fallax, Say.

introferens, Bland.

Van Nostrandi, Bland.
Also, Jacksonville, Florida.

Mesodon major, Binney.

On Plate I. Fig. 2, I have figured the dentition of an individual of this spe-
cies differing from that figured in Vol. V. Plate VIII. Fig. G, by wanting the

side cusps and cutting points of the central and
first lateral teeth. The individual from which the
lingual was extracted is labelled B in the collec-
tion given by me to the United States National
Museum. Fig. 3 gives an outer lateral of the
same membrane, on which the side cusp and cut-
ting point are present. Fig. 1 gives a central tooth
with side cusps and cutting points from the mem-
brane of the specimen labelled A.

Mesodon major. _,, „ , . <• • , •

The figures show a larger range of variation in
the dentition of individuals of the same species than would have been antici-
pated. (See also M. Andrcwsi.)

Mesodon albolabris, Say.

Andrewsi, W. G. B.

In the Manual of American Land Shells, p. 302, I have described and fig-
ured specimens of a larger form of this species, which would be called major
by most collectors, but which has the genitalia and lingual dentition of An-
drewsi. (See figure above.)

The penis sac of Andrewsi was described by me as constricted in the middle.
Further study has convinced me that it is rather twisted than constricted.
On Plate I. Fig. 4, I give a figure of the genitalia to show this ; and in Fig. 5,
the penis sac of still another individual

MUSEUM OF COMPARATIVE ZOOLOGY. 191

In studying the lingual membrane of many individuals of M. Andreiosi, I
have found some variation. I give here notes on membranes of specimens
labelled as specified in the Binney collection in the United States National
Museum.

AA. 60-1-60 teeth, with about 14 laterals on each side.

N. 51-1-51 teeth, with 11 laterals ; some extreme marginals have decid-
edly multifid cusps.

Q, from Hayesville, N. C, has also about 11 laterals.

V has 9 laterals, 60-1-60 teeth.

M. 60-1-60 teeth, with about 14 laterals. Some outer laterals have side
cusps : one is figured on Plate I. Fig. 12.

G has same count as M ; no side cusps to outer laterals.

N has 64-1-64 teeth, with 14 laterals. The extreme laterals have side
cusps.

L has 61-1-61 teeth, with 11 laterals ; no side cusps on outer laterals.

J same. 64-1-64 teeth, with 14 laterals.

B. 60-1-60 teeth, with 16 laterals, none with side cusps.

F. All laterals, even first, have decided side cusps (see Plate I. Fig. 10)
and cutting points: and marginals also (Fig. 11). 50-1-50 teeth, with 15
laterals.

K. 53-1-53 teeth, with 14 laterals.

I. 50-1-50 teeth, outer laterals with side cusps.

O. 68-1-68 teeth, with 14 laterals.

As remarked above, most collectors will refer this large form of Andrewsi to
major. It differs from that species as hitherto understood very decidedly
in its lingual dentition and genitalia. In its shell, also, the species differs
from the generally known major in so marked a manner, that from it alone I
could say, before examination, what were the characters of the dentition and
genitalia of every specimen collected by Mr. Hemphill in the mountains of
North Carolina. One of the puzzling questions to be left to future solution is
the limitation of albolabris, major, and Andrewsi. It must be studied from the
lingual dentition and genitalia, as well as from the shell. The student must
also consider whether the Helix major of the Boston Journal and of the Ter-
restrial Mollusks are the same species.

Practically, the simplest way of treating specimens in collections is to refer
to a variety of albolabris all forms more resembling that species than they do
the major of the Terrestrial Mollusks, and to call major all specimens most
nearly conforming to the figure and description of that species in Terrestrial
Mollusks of U. S., Vols. II. and III. In the former category would be placed
the major of the Boston Journal; in the latter, the, large forms I have referred
to Andrewsi in Manual of American Land Shells, such, for instance, as are fig-
ured in Fig. 322£, repeated here, ante, page 190. This variety of albolabris
and this major, as above identified, would be found to differ widely in den-
tition and genitalia, the former in these respects resembling albolabris, the

192 BULLETIN OF THE

latter Andrewsi. The latter species must also be recognized as subject to
variation, rendering it in some cases difficult to separate from major, — never
from the large variety of albolabris.

The original specimen of major of the Terrestrial Mollusks was included in
the collection given by Mr. J. S. Phillips to the Philadelphia Academy oi
Sciences. The points in which it differs from the large form of albolabris are
pointed out in Terrestrial Mollusks, Vol. II. p. 98.

Mesodon multilineatus, Say.

Pennsylvanicus, Green.
Mitchellianus, Lea.
elevatus, Sat.
Clarki, Lea.
Christyi, Bland.
exoletus, Binnet
Wheatleyi, Bland.
dentiferus, Binney.
In a specimen collected by Mr. Hemphill, at Banner's Elk, N. C, I found the
etractor muscle of the penis sac near its junction with the vas deferens, not
at half the length of the latter. There was no constriction to the penis sac.

Mesodon Wetherbyi, Bland.
thyroides, Say.
claUSUS, Say.

Downieanus, Bland.
Lawae, Lewis.
profundus, Say.
Sayi, Binney.

Pupa pentodon, Say.

The enlarged view of the aperture gives on the left P. Tappaniana, on the
right P. curvidens.

Under the name of Pupilla Floridana, Mr. Dall has described what I con-
sider as a form of this species in Proc. U. S. Nat. Mus., 1885, p. 251, Plate
XVII. Fig. 11.

Shell greenish spermaceti-white ; when living, the tissues of the animal show
with pale salmon-color through the shell in the apical whorls ; surface smooth or
lightly striated, with a tendency to retain dirt upon itself ; form subcylindrical, with
a rather obtuse apex, the last whorl forming nearly half the shell ; suture evident ;
whorls five, neatly rounded ; aperture longer than wide ; lip white, thin, reflected ;
teeth about nine, of which there are generally three larger than the rest, their tips
nearly meeting, and their bases mutually nearly equidistant ; one is on the pillar,
one on the body whorl, and one on the anterior margin ; on either side of the latter
are two generally subequal much smaller denticles. Lon. 1.60, lat. 0.75 mm.

MUSEUM OF COMPARATIVE ZOOLOGY. 193

Habitat. — Under loose oak bark, oak hamak, Archer, Alachua County, Florida,
April, 1885, W. H. Dall, sixteen specimens.

This is one of our smallest species, and is related to P. pentodon and P. pellucida.
It is about half the size of the former and much more slender. Its teeth recall
those of P. curvidens, Gould, in their arrangement, but the shell is more cylindrical
and smaller than it is in P. pellucida (servilis) as figured by Gould. The teeth are
more numerous than in the latter shell, and set, as in P. pentodon, in one series ;
not, as in pellucida, partly deeper in the throat.

I describe this with some hesitation, for the condition in which the Pupidae and
Vertigos of North America are is most unsatisfactory, and offers an excellent field
to some careful student who shall be able to examine and figure large series of
authentic specimens. Still, as there is absolutely no other form with which I feel
able to unite this one, it is better to give it a name than to leave it erroneously
with some other species.

The above description is copied from that of Dall, while the figure, Plate
XVII Fig. 11, is copied in my Plate III. Fig. 2. I have seen no specimen of it.

Pupa fallax, Say.

armifera, Say.
contracta, Say.

Pupa Holzingeri, Sterki.

Shell narrowly perforated, turrited-cylindrical, vitreous ^or whitish), very
minutely striate, shining ; apex rather pointed ; whorls 5, regularly increasing,
well rounded, especially the upper ones, the last somewhat narrowed and a
little ascending towards the aperture, compressed at the base but not carinated,
at some distance from the outer margin provided with an oblique, rather prom-
inent, acute crest corresponding in direction to the lines of growth, extending
from the base to the suture, formed by a whitish callosity; behind the crest the
whorl is flattened, and corresponding to the lower palatal lamella, impressed;
aperture lateral,' scarcely oblique, relatively small, inverted subovate, with a
slight sinus at the upper part of the outer wall, margins approximated ; peri-
stome moderately reflected; lamellae 6; one parietal, rather long, very high, in
its middle part curved outward, towards the aperture bifurcated, the outer
branch reaching the parietal wall ; one columellar, longitudinal, rather high,
its upper end turning in nearly a right angle towards the aperture, but not
reaching the margin ; basal exactly at the base, short, high, dentiform ; 3 in
the outer wall, viz.: the lower palatal long, ending in the callus, highest at
about its middle ; the upper short, rather high on the callus ; above the upper,
one supra-palatal, quite small, dentiform, nearer the margin.

Length 1.7 mm., diam. 0.8 mm. = .068 X -032 inch.

As already stated, our species ranges beside P. armifera and P. contracta,
Say, standing nearer the latter. Yet it is different from this species by the
shape of the aperture, the wanting callus1 connecting the margins on the

1 In many specimens of P. contracta so strongly developed that the peristome is
-endered continuous.
vol. xix. — no. 4. 13

194 BULLETIN OF THE

body whorl, by the longer crest behind the aperture, which in contracta disap-
pears in about the middle of the (height of the) whorl, and by the wanting
constriction, especially in the columellar wall, not to speak of the size and
shape of the whole shell. The lamellae also show some marked differences,
such as the presence of a high basal, the shorter columella not reaching the
base, but with relatively larger horizontal part, the bifurcation of the parietal
and the presence of a supra- palatal, the last just as it is in P. armifera.

It must be added here that the specimen first obtained from Minnesota in
several respects differs from those found in Illinois and
Iowa, which I consider as typical ; by its size which is one
third smaller, by the basal lamella developed in a peculiar
way, being rather longer at the truncated top than at its
foot, and by the stronger, thicker palatal lamellae. Yet, as
there was only one specimen, it was liable to be an individ-
ual peculiarity, — even then of interest. Should, however,
more specimens be found with the same configuration, they
would represent a distinct and well characterized variety ;
Pupa Hoijringeri, possibly it is a peculiar northern form,
enlarged New Philadelphia, Ohio, June, 1889.

The above is a description by Dr. V. Sterki ! of a Pupa received by him
from Winona, Minn., and Northern Illinois. He kindly furnished me the
above figure.

Pupa rupicola, Sat.

corticaria, Sat.
Vertigo milium, Gould.

ovata, Sat.
Succinea retusa, Lea.
ovalis, Sat.
avara, Say.
aurea, Lea.
obliqua, Sat.

SOUTHERN REGION SPECIES.

Glandina Vanuxemensis, Lea.
truncata, Sat.
bullata, Gould.
decussata, Pfeiffer.
Texasiana, Pfeiffer.

Lingual membrane as usual in the genus. Teeth 35-1-35. Central small,
narrow, with a single blunt rounded cutting point. See Plate IX. Fig. G.

i The Nautilus, Vol. III., No. 4, p. 37, August, 1889.

MUSEUM OF COMPARATIVE ZOOLOGY.

195

Zonites caducus, Pfeiffer.

cerinoideus, Anthont.
Gundlachi, Pfeiffek.
Found also in Texas, at Hidalgo, by Dr. Singley.

Zonites Singleyanus, Pilsbky.

Shell minute, broadly umbilicate, planorboid, the spire scarcely perceptibly ex-
serted; subtranslucent, waxen white, shining, smooth, under a strong lens seen to
be slightly wrinkled by growth-lines; whorls three, rather rap-
idly increasing, separated by well impressed sutures, convex, the
apex rather large; body whorl depressed, slightly descending,
indented below around the umbilicus ; aperture small, semilunar,
oblique; peristome simple, acute. Umbilicus nearly one third
the diameter of the shell, wide, showing all the whorls.

Alt. 1, diam. 2 mm.

New Braunfels, Comal Co., Texas.

Allied to Z. minusculus, but much more depressed, more shin-
ing, smoother, smaller, with broader umbilicus and a complete
whorl less than minusculus.

This species, one of the most distinct of the smaller forms of
Hyalina, was communicated to me by Mr. J. A. Singley, in whose Zoniteen^r|edyanUS'
honor it is named. I have also found a few specimens among the
shells collected by myself in Central Texas, during the winter of 1885-86. With
Z. Singleyanus at New Braunfels are found quantities of Z. minusculus. The latter
species exhibits some variation, being often more depressed than more northern
specimens. This depressed form has been noticed in Mexico by Strebel, who pro-
poses for Z. minusculus the new generic title of Chanomphalus, which is, of course,
completely synonymous with Pseudohyalina, Morse, 1864, and this, again, is not dif-
ferent enough from Hyalina to warrant the erection of a new genus or subgenus.
There is some variation in the width of the umbilicus in Texan specimens of Z. mi-
nusculus, but I have not seen specimens with it so wide as Dr. Dall indicates for
his var. Alachuana from Florida. H. elegantulus, Pfr., is about the size and form of
my Zonites Singleyanus, but it is a strongly sculptured species.

The above description was published by Pilsbry, Proc. Phil. Acad., N. S.,
1889, p. 84, Plate XVII. Figs. 6, 7, 8. A specimen kindly furnished me by
Dr. Singley for the purpose is drawn in my figure.

Zonites Dallianus, Simpson.

Shell minute, depressed, narrowly umbilicated, fragile, pale straw-
colored, somewhat shining ; under a lens seen to be marked with
delicate growth-lines above, smoother beneath. Spire a little con-
vex ; apex subacute ; sutures scarcely impressed. Whorls three
and one half, scarcely convex, the last wide. Aperture oblong-
lunate, oblique, upper and lower margins sub-parallel, slightly con-
verging; peristome acute. Alt. 1J, diam. maj. 3, min. 2\ mm.

West Florida, at Shaw's Point, Manatee Co., and Little Sarasota
Ray.

Zonites
Dallianus,
enlarged.

196 BULLETIN OF THE

Differs from Z. arboreus, Say, in the smaller spire and wider last whorl; fewer
whorls ; differently shaped aperture. It is about half the size of Z. arboreus, and
the sculpture is the same as in that species. The Helix Ononis of Pfeiffer, of
which specimens from Cuba and Hayti are before me, has no special relationship
to this species, but js undoubtedly a synonym of Z. arboreus, as Pfeiffer himself
concluded. H. Ottonis differs from arboreus in nothing but the lighter color ; the
form and dimensions are precisely as in arboreus. (See Pfr. in Wiegm. Archiv fur
Naturgeschichte, 1840, p. 261 ; the species was never described in the Monographia
Heliceorum.)

The aperture in Z. Dallianus is less lunate than in Z. arboreus, embracing less of
the penultimate whorl; seen from beneath, the greater portion of the aperture lies
outside of the periphery of the penultimate whorl ; whilst in Z. arboreus the reverse
is the case. The much smaller size of Dallianus also separates it from Z. arboreus.

This species was sent me under the above name by Mr. Charles T. Simpson, the
well known student of Floridian shells. The same form I find in the museum of
the Academy, collected by Mr. Henry Hemphill.

The above description was published by Mr. Pilsbry in Proc. Phil. Acad. ,
N. S., 1889, p. 83, Plate III. Figs. 9, 10, 11. A specimen kindly furnished
me for the purpose by Mr. Pilsbry is also figured above.

Microphysa incrustata, Poet.
VOrtex, Pfeiffer.

All the specimens received from West Florida collected by Mr. Hemphill,
and from East Florida by Mr. G. W. Webster, are heavily incrusted with dirt.

Microphysa (?) dioscoricola, C. B. Adams.

Shell minute, subperforate, conic globose, thin, very delicately striate, horn-
colored ; spire elevated, obtuse ; whorls 3-3^, convex, the last
medially subimpressed; aperture lunately rounded ; peristome
simple, acute, the columellar margin subvertically descend-
ing, very slightly reflected, diam. greater If, lesser If, height
1£ mm. (Pfr.).

This species is placed by Von Martens (Die Heliceen, p. 73)
in Conulus, a subgenus of Hyalina, with fulvus, Gundlachi, and
Microphysa others. Mr. Dall tells us (Nautilus, III. 25) that it belongs to
den8iarK.Cdla' Microconus. This last is synonymous with Microphysa, a sub-
genus of Zonites, according to Tryon, Syst. Conch., III. 24.
Mr. Dall ays also that the species was originally described from Jamaica by
Adams, and subsequently from Trinidad by Guppy as cceca. In its jaw and
lingual dentition it seems to agree with most of the other species of Microphysa
which I have examined. I retain it, therefore, irt that genus.

The species seems widely distributed in Florida. St. Augustine ; Blue
Spring, St. John's River ; Lake Worth to Hawk's Park along the east coast;
Hilo River, emptying into Mosquito Inlet, east coast, not Hillsborough River,
emptying into Tampa Bay, as stated by Dall. The specimens examined by me

MUSEUM OF COMPARATIVE ZOOLOGY. 197

were collected by G. W. Webster at Hawk's Park, " widely distributed in dry
places, where other species are not found." Also at Hidalgo, Texas (Singley).

The shell is figured on preceding page.

The jaw (Plate III. Fig. 6) is high, strongly arched, with acuminated ends ;
it is very thin, membranous, light horn-colored and transparent ; there are
numerous — some fifteen on each side the median line — narrow, delicate ribs,
running obliquely to this line, denticulating either margin ; on the upper
median portion the ribs meet before reaching the lower margin, leaving upper,
median, triangular plates as in Orthalicus. The jaw is quite such as I have
described and figured for Macroceramus in Terr. Moll., V. 384. It also resem-
bles that of Microphysa turbiniformis (Ann. N. Y. Acad. Sci., III., Plate XV.
Fig. C), excepting that the latter wants the upper median triangular plates.
A greatly magnified view of the central portion of the jaw is given.

The lingual membrane is long and narrow. Owing to its small size, it was
very difficult to determine the shape of any but the lateral teeth. Three of
these last are figured on Plate II., Fig. 5, drawn by camera lucida. They have
wide, square bases of attachment, bearing, as usual, two cusps, both stout and
blunt, and bearing short, stout cutting points ; the centrals appCar of the same
shape and tricuspid, but I failed to distinguish them clearly enough to draw
by camera ; the laterals are separated, low, wide, quadrate, with long irregu-
larly serrated cusp. I failed also to distinguish these clearly enough to draw
by camera. I have represented them in the figure as they appeared to me.
The laterals seem like the teeth of Pupa, the marginals much like those of
Cionella svhcylindrica. The dentition is somewhat similar to what I have fig-
ured of vortex on page 356 of the Manual of American Land Shells. There
are about 15-1-15 teeth, with six perfect laterals on each side the median line.

Mr. Dall says of this species that the shell is much smaller than that of
granum, olive-greenish, with a silky lustre and few inflated whorls, the first
of which is usually finely punctate. The suture is very deep, and the umbili-
cus is proportionally larger than in granum.

The figure of the dentition of an undetermined species found by Dr. W. M.
Gabb, in Costa Rica, published by me in the Annals of the New York Acad-
emy of Science, Vol. III. p. 261, Plate XI. Fig. G, is said by Mr. Pilsbry to
represent that of this species, — he having identified the shell from which the
lingual was extracted to be H. cazca, Guppy.

Hemitrochus varians, Menke.
Strobila Hubbardi, Brown.

Polygyra auriculata, Sat.

Dall (U. S. Nat. Mus. Proc, 1855, p. 263) thus characterizes a variety
microforis : — ■

This form is quite well marked, and when fully adult shows as a rule little vari-
ation from the form figured by the Binneys, and generally regarded as typical. A
quite uniformly characterized variety was found, however, by me at Johnson's

198 BULLETIN OF THE

Sink, Alachua County, Florida, where it was abundant. Some twenty specimens
were picked up in a few moments during a hurried visit made with other ends in
view, and a quart could easily have been gathered in half an hour. This form is
distinguished by its generally smaller size (max. diam. 12.0, min. diam. 10.0, alt.
6.0 mm.) as compared with the type (15.0, 12.0, and 7.9 mm.), and by being more
closely rolled, thus having not only an actually smaller umbilicus, but one in
which one third less of the preceding whorl is visible. The specimens were uni-
form iu this, and in all other respects were like the typical auriculata.

Polygira uvulifera, Shottleworth.
auriformis, Bland.
Postelliana, Bland.
espiloca, Bland.
a vara, Say.
ventrosula, Pfeiffek.
Hindsi, Pfeiffer.
Texasiana, Moricand.
triodontoides, Bland.
Mooreana, w. G. B.
hippocrepis, Pfeiffer.

Through the kindness of Mr. Singerly, I have the opportunity of examining
the jaw and lingual membrane.

Jaw long, low, ends blunt ; anterior surface with over 14 ribs denticulating
either margin.

Lingual membrane long and narrow (Plate III. Fig. 8, a, b). Centrals tri-
cuspid, laterals bicuspid, marginals low, wide, irregularly denticulate. Teeth
30-1-30, the ninth lateral having its inner cutting point bifid.

Polygyra Jacksoni, Bland.

A form was found abundantly near Fort Gibson, Indian Territory, by Mr.
C. T. Simpson, who thus describes it in Proc. U. S. Nat. Mus., 1888, p. 449.

Instead of the bicrural tooth on the body whorl, at the aperture there is a heavy
elevated deltoid callus, which is joined to the upper and lower margins of the peri-
stome, and which occupies about the same area as the tooth in the type. The num-
ber of whorls is 5 ; greater diam. 7, lesser 6, height 3 mm. In examining several
hundred specimens, I have found none which approach the type, and I would
therefore propose for it the varietal name of deltoidea.

Polygyra oppilata, Moricand.
Dorfeuilleana, Lea.
Ariadnse, Pfeiffer.
septemvolva, Say.
cereolus, Muhlfeldt.
Carpenteriana, Bland.

MUSEUM OF COMPARATIVE ZOOLOGY.

.199

Polygyra Febigeri, Bland.
pustula, Ferussac.
pustuloides, Bland.

Triodopsis Hopetonensis, Shuttleworth.
Levettei, Bland.

See 2d Suppl. This species may perhaps be considered one of the Central
Province. A variety, however, approaches very nearly the Indian Territory
shell lately described as Mesodon Kiowaensis. This variety is toothless. It is
smooth, like Levettei, and has six whorls.

Triodopsis vultuosa, Gould.
Copei, Wetherby.

See 2d Suppl. To the synonymy add Triodopsis Cragini,
Call, Bull. Washburne Coll. Library, I, No. 7, p. 202, Fig. 5,
Dec, 1888, Topeka, Kansas. I have seen an authentic speci-
men, given by Mr. Call to the National Museum. It is figured

here.

Mesodon Romeri, Pfeiffer.

divestus, Gould.

The tvpical form, has few separated, very stout ribs ; a va- Triodopsis Cragini,
riety from Eufala, Indian Territory, sent me by Mr. C. T.
•Simpson, has numerous fine ribs and revolving microscopic lines. One in-
dividual is 24 mm. in greater diameter.

Mesodon jejunus, Sat.
See Manual of American Land Shells, p. 390.

Mesodon Kiowaensis, Simpson.

Shell umbilicated, orbicularly depressed, solid, dark brown in color ; whorls
5, with rather coarse striae, and fine revolving impressed lines,
which are much more conspicuous on the last whorl. Suture
deeply impressed, leaving the whorls well rounded ; aperture
oblique, somewhat transversely rounded, forming fully three
fourths of a circle ; peristome thick and solid, whitish or pur-
plish, evenly reflected, with a slight constriction behind it ;
umbilicus moderate, deep, exhibiting but little more than one
of the whorls. Greater diam. 15, lesser 13, height 7 mm.

Kiowa Station, about thirty specimens, mostly dead. Lime-
stone Gap, two dead specimens. Another badly bleached shell
was obtained not far from Eufaula (Indian Territory).

Jaw with 9 ribs; teeth with fewer laterals than Sayii, and the inner cusp is
bifid on the marginals, while in Sayii it is entire (Simpson).

Mesodon
Kiowaensis.

200 BULLETIN OF THE

The foregoing description is copied from the Proceedings of the U. S.
National Museum, 1888, p. 449, while the figure is drawn from a specimen
kindly furnished by Mr. Simpson.

The shell appears to me to be a toothless form of some Triodopsis, rather than
a Mesodon (see above, under Triodopsis Levettei). It also resembles nearly
some of the toothless forms of Triodopsis Mullani.

Acanthinula granum, Strebel and Pfeiffer.

Shell small, umbilicated, thin, scarcely shining, light horn-colored, with
rib-like striae of growth, crossed obliquely wTith rib-like
folds, in fresh specimens hirsute or with punctate epi-
dermis. Whorls 4|, four of them broad, rounded, regu-
larly increasing in size, rapidly in elevation, the last
descending, impressed at the umbilicus. Peristome
simple, broadly reflected at its columellar margin, par-

Acanthinuia granum, tially covering the deep umbilicus, within with whitish,
enlarged. '

light thickening. Greater diam. 2.8, lesser 2.6, height

2.8 mm.; of aperture, height 1.2, breadth 1 mm. (Strebel and Pfeiffer.)

Acanthinula granum, Strebel and Pfeiffer, Beitrag zur Kennt. der F. Mex. L.
und S. W. Conch., IV., 1880, p. 31, Plate IV. Fig. 13, not Plate IX., as quoted
in text.

A Mexican species, found also in Florida; Archer, Alachua Co.; Evans
Plantation, Rogers River; Lake Worth (Dall).

Mr. Dall says the shell, when perfect, is nearly the size of labyrinthica, very
thin, reddish brown, with very deep sutures and a rather deep, small tubular
umbilicus. It is covered with beautiful deep oblicpie epidermal ridges, which
are easily lost, and do not agree with the lines of growth.

The figure is drawn from a specimen kindly furnished by G. W. Webster.

Dorcasia Berlandieriana, Moricand.
griseola, Pfeiffer.

Bulimulus patriarcha, W. G. B.
alternatus, Say.

I am assured by Dr. Singerly and Mr. Simpson that the form known as
alternatus does not always have a dark aperture, and the intermingling of the
forms leads an observer on the spot to believe alternatus, Schiedcanus, Moore-
anus, and dcalbatus varieties of one and the same species. They were so treated
by my father in Vol. II.

Bulimulus Schiedeanus, Pfeiffer,
var. Mooreanus, W. G. B.
dealbatus, Sat

MUSEUM OF COMPARATIVE ZOOLOGY. 201

Bulimulus serperastrus, Sat.
multilineatus, Sat.
Dormani, W. G. B.

Bulimulus Floridanus, Pfeiffer.

I have already in Terr. Moll, IV., Plate LXXIX. Fig. 3, figured the front
view of the typical specimen in Mr. Cumings's collection, drawn by Mr. G. B.
Sowerby. The back view is now offered (Plate III. Fig. 7), received from the
same source.

A comparison of the front view of Mr. Sowerby's drawing referred to above,
with the figure of Bulimulus Hemphilli (Plate III. Fig. 9), recently received
from Mr. George W. Webster, will lead one to believe the
two to be identical. I so suggested in Manual of American
Land Shells (p. 408), when treating the variegated shell fig-
ured in Fig. 449 of that work, here repeated. There appear
to be two varieties of coloring, one corresponding to Pfeiffer's
description, and one to Sowerby's figure.

I give the description of B. Hemphilli in full, though I be- Bulimulus
lieve it to be identical with Floridanus.

Shell imperforate, very thin, transparent, amber-colored and marked by coarse
lines of growth ; body whorl witli si: revolving and slightly interrupted brownish
red bands, the lower two being close together and upon the rounded base, spire
obtuse, whorls five, slightly convex, the body whorl constituting two thirds of the
entire length of the shell. Suture slight, base uniformly and gracefully rounded.
Aperture direct and oval, peristome thin. Length, 19 mm. ; diameter, 8 mm.
Hab. both coasts of South Florida.

Remarks. Mr. Henry Hemphill, of San Diego, Cal., first found a few dead
and badly preserved specimens of this shell in 1884, at Marco, west coast of
Florida. These Mr. Binney thought identical with B. Floridanus, Pf. (See Manual
of American Land Shells, 1885.) Numerous specimens collected during the past
summer by the author and Mr. G. W. Webster and son, prove beyond a doubt
that this is not identical with the shell figured and described on page 407 of Mr.
Binney's Manual. The B. Hemphilli is more ventricose, not angular at base, im-
perforate, differs in color, and in fact there is a general difference.

Mr. Berlin H. Wright describes the above species in the West American
Scientist, San Diego, April, 1889, p. 8. He found also a variety of uniform
light brown or russet color, bandless, which I have figured on Plate III. Fig. 9.
This form had a jaw and lingual membrane the same as in B. Marielinus
and Dormani

Bulimulus Marielinus, Poet.
Cylindrella Poeyana, D'Orbignt.
jejuna, Sat.

202

BULLETIN OF THE

Macroceramus pontificus, Gould.

I give bere, for comparison, a figure of the true M. Kieneri, from a type in
Dr. Pfeiffer's collection, from Honduras.

Macroceramus Kieneri.

Macroceramus Gossei.

Macroceramus Gossei, Pfeiffer.

The figure given represents the species.

Pupa variolosa, Gould.

modica, Gould.

pellucida, Pfeiffer.
Strophia incana, Binnet.
Holospira Romeri, Pfeiffer.

Pfeiffer says " allied to Goldfussi, but from all species easily recognized by
the basal carina of the last whorl, and its singular twist, which at first sight
gives a sinistral appearance to the shell."

Holospira Goldfussi, Menke.
Stenogyra octonoides, D'Orb.

SUDUla, Pfeiffer.

gracillima, Pfeiffer.
Csecilianella acicula, Muller.
Liguus fasciatus, Muller.

See p. 435 of Manual of American Land Shells for still another variety of
coloring of this species.

Orthalicus undatus, Bruguiere.
Succinea Concordialis, Gould.

luteola, Gould.

effusa, Shuttleworth.

Salleana, Pfeiffer.

campestris, Sat.
Veronicella Floridana, Binnet.

MUSEUM OF COMPARATIVE ZOOLOGY. 203

Onchidium Floridanum, Dall.

See Plate VI. Figs. B, C, for a drawing of an original specimen, enlarged
three times.

To Mr. Hemphill is due the credit of adding this genus to the fauna of Eastern
North America. The specimens arrived as this paper is going through the press,
and a detailed description must be deferred. The following notes, however, will
indicate its external characters : —

When living, the creature is of a uniform slaty blue, the under parts bluish
white, with a greenish tinge to the veil. The surface appears beautifully smooth
and velvety without dorsal tubercles ; just within the slaty margin of the mantle
is a single row of about (in all) one hundred whitish elongated tubercles. When
crawling, it is of an oval shape, about an inch long, and two tentacles extend for-
ward beyond the mantle margin, resembling the oculiferous ones of Vaginalis
Floridanus. In spirits the surface is still smooth, but numerous circular harci'y
elevated domelets cover the back, each appearing to contain one of the dorsal eyes
described by Semper. The tentacles are entirely retracted ; a narrow veil, with
lightly escalloped edge, precedes the head ; the muzzle is not prominent, is in-
dented in the middle, and puckered at the edges. The foot is about one third
wider than the mantle at each side of it. There is no jaw. The penis resembles
that of Siphonaria in form and position. The animal exudes very little mucus. It
was found on rocks between tides associated with Chiton picens. Fifteen speci-
mens were found at Knight's Key by Hemphill.

Onchidium indolens of Couthouy (Rio) and 0. armadillo of Miirch differ from the
above in coloring. The latter, described from St. Thomas, has a very different
dorsal surface. No others are known from East America. It would seem as if
the small Northern species, possessing a jaw like 0. boreale, Dall, and 0. Celtieum,
Cuvier, might appropriately be separated from the agnathous tropical forms as a
subgenus, for which the name of Onchidella might be revived in a restricted sense.

The above description is by Dall (Proc. U. S. Nat. Mus., 1885, p. 288).
Specimens received by him have the lingual dentition of the genus. (See my
Plate III. Fig. 10, where a central tooth and adjacent lateral are given.) There
are numerous rows of over 97-1-97 teeth.

The following are to be added to the species treated in the Second Sup-
plement.

PACIFIC PROVINCE SPECIES.

Microphysa Stearnsi, Bland.
Lansingi, Bland.

It must be borne in mind that the other species of Microphysa examined by
me have quadrate marginal teeth, while Stearnsi and Lansingi have the acule-
ate marginal teeth of the Vitrininre. Thus they can hardly be classed in
Microphysa. The name Pristina has been suggested by Ancey (Conchologists'

204 BULLETIN OF THE

Exchange, I. 5, p. 20, Nov., 1886). As a substitute for this preoccupied name,
Mr. Pilsbry suggests Anceyia. (See same, I. 6, p. 26, Dec, 1886.) Mr.
Ancey's description is: —

Pristina, Anc. (nov. subg. Hyalinae). Testa parvula, imperforata, cornea, nitens,
multispirata ; spira depresse conica. Apertura interdum lamellis radiantibus sub-
serratis in palato sitis insignis.

Geographical Distribution : Western and Arctic North America.

Types : Hyaltna Stearnsi, Bland, and Lansingi, Bland.

Mr. W. G. Binney put these species, but with doubt, in Microphysa, while other
authors consider them as Hyalinae ; they differ from the latter by anatomic fea-
tures, and from the former by the form of the shell. Altogether I am inclined to
place the group in Hyalina, as a series nearly allied to Conulopolita, Boettger
(type, C. Raddei, Boettg.) ; I am confident the presence or absence of internal
laminae or tooth-like processes within the aperture of Helices are not generic char-
acters ; in some instances they are either present or absent in closely allied species.
I established this fact when at work (Le Naturaliste, 1882) on the New Caledonian
forms, and I now repeat this as my opinion in regard to Pristina and Gastrodonta.
In the latter the teeth are freauently absorbed by the animal when growing larger.

Macrocyclis Duranti, Newc

To the synonymy add : —

Selenites coelatura, Mazyck, Proc. U. S. Nat. Mus., 1886, p. 460, with figures of that
form and of typical Duranti. Also, Proc. Elliott Soc, Feb., 1886, p. 114, same
figures.

Mr. Mazyck's description and figures are repeated here : —

Shell small, depressed, brownish horn-color, with very coarse, rough, crowded,
sub-equidistant, irregular ribs, which are obsolete at the apex;
whorls four, rounded, somewhat inflated below, gradually in-
creasing, the last not descending at the aperture ; suture im-
pressed ; umbilicus wide, clearly exhibiting all of the volutions ;
aperture almost circular, slightly oblique ; peristome simple, its
ends approaching and joined by a very thin, transparent, whitish
callus, through which the ribs are distinctly seen. Greater
diameter, 4 mm.; height, If mm.

Santa Barbara, California, Dr. L. G. Yates. Hayward's, Ala-
meda County, California, W. H. Dall, U. S. National Museum.
Macrocyclis Duranti, Newcomb's description of this little shell (M. Duranti) is as

var. ceelata, follows : —

enlarged.

"Shell depressed, discoidal, pale corneous, under the lens

minutely striated, opaque, broadly and perspectively umbilicated ; whorls 4, the last

shelving but not descending (at the aperture); suture linear; aperture rounded,

lunate, lip simple, the external and internal approaching.

" Habitat. — Santa Barbara Island."

Mr. Binney's description, which is repeated in each of his works above named,
differs in this important particular. For Newcomb's " Under the lens minutely
striated," he substitutes the contradictory words " with very coarse, rough striae."

MUSEUM OF COMPARATIVE ZOOLOGY. 205

In a note written in answer to an inquiry addressed to him regarding this singular
discrepancy, he says, " My description and figure are from an individual, not from
the species. I am absolutely sure my specimen was one of the original find."
His figure, drawn by Morse, rather represents a comparatively smooth, semi-
transparent shell.

Limax hyperboreus.

See Manual of Amer. Land Shells, p. 473. I have figured on Plate VIII.
Fig. F, an individual from British Columbia. Here I give the dentition.

Jaw arched, smooth, with blunt median projection. Lingual
membrane with 42-1-42 teeth ; centrals tricuspid ; laterals bi-
cuspid, 12 in number on each side; marginals about 30 on each
side, aculeate, simple, without bifurcation or side spur.

The figure shows a central tooth with its adjacent lateral, and
three extreme marginals.

Limax montanm, L. castaneus, L. occidentalis, and L. campes-
tris all have side spurs to their marginal teeth. Otherwise, their
dentition shows no specific distinction from that of hyperboreus.
Until the genitalia of the last is shown to vary, I am inclined Limai hyper-
to believe all four to be one and the same species.

Limax Hemphilli.

Mr. Henry Hemphill has sent me in spirits from Julian City, California, a
small, slender, smooth, dark species of Limax, 20 mm. long in its contracted
state. It does not outwardly resemble Limax agrestis, nor does it seem prob-
able that that species would have been accidentally introduced from the Eastern
cities.1 The dentition, however, agrees with that of agrestis by its having the
peculiar side spur to the larger cutting point of all the lateral teeth. I venture
to propose a specific name for it, in hopes of having an opportunity later to
fix its specific position by an examination of the genitalia. It is figured on
Plate VIII. Fig. E.

The jaw is as usual in the genus.

There are 50-1-50 teeth to the lingual membrane, of which ten on each
side are laterals. Centrals tricuspid; laterals bicuspid, the larger cutting point
having a well developed side cutting point on its inner side ; the laterals have
also an inner, slightly developed, horizontal side cusp, bearing a small, stout
cutting point (see Plate I. Fig. 13); marginals simple, without side spur.

The figure on Plate II. Fig. 3, shows one central with its adjacent laterals,
an outer lateral, and several extreme marginals.

A specimen, apparently of the same species, from British Columbia, has
53-1-53 teeth, of which 13 on each side are laterals.

I have the same species, with similar dentition, from San Tomas, Lower
California (Hemphill).

1 It is, however, found in San Francisco

206 BULLETIN OF THE

Limax Hewstoni, J. G. Cooper.

On Plate II. Fig. 4, will be found a better figure of the dentition of this
species than is given in Terr, Moll., V. It will be seen that the inner side
cusp of the lateral teeth is quite distinct from the side spur found in Limax
Hemphilli and agrcstis. (See line third of p. 223.)

I have figured (Plate VIII. Figs. D and I) individuals received from Dr.
Cooper, drawn by Mr. Theo. D. A. Cockerell.

Limax campestris, var. occidentalis.

The specimen figured on Plate VIII. Fig. H, was kindlj- furnished by Dr.
Cooper. I have already expressed my belief in the identity of this with the
Eastern form.

Arion foliolatus, Gould.

It is with the greatest pleasure that I announce the rediscovery by Mr.
Henry Hemphill of this species, which has hitherto escaped all search by
recent collectors. It has till now been known to us only by the description
and figure of the specimen collected by the Wilkes Exploring Expedition,
almost fifty years ago, and given in Vols. II. and III. of Terrestrial Mollusks.
A single individual was found in December, 1889, at Olympia, Washington,
and sent to me living by Mr. Hemphill. It can thus be described. (See
Fig. A of Plate VIII.)

Animal in motion fully extended over 100 millimeters. Color a reddish
fawn, darkest on the upper surface of the body, mantle, top of head, and eye-
peduncles, gradually shaded off to a dirty white on the edge of the animal,
side of foot, back of neck, and lower edge of mantle, and with a similar light
line down the centre of back ; foot dirty white, without any distinct locomo-
tive disk ; edge of foot with numerous perpendicular fuscous lines, alternating
broad and narrow ; mantle minutely tuberculated, showing the form of the
internal aggregated particles of lime, the substitute of a shell plate, reddish
fawn color with a central longitudinal interrupted darker band and a circular
marginal similar band, broken in front, where it is replaced by small, irregu-
larly disposed dots of same color ; these dots occur also in the submarginal
band of light color. Body reticulated with darker colored lines, running
almost longitudinally, scarcely obliquely, toward the end of the tail, and con-
nected by obliquely transverse lines of similar color, the areas included in
the meshes of this network covered with crowded tubercles, as in Prophysaon
Andcrsoni, shown in Plate IX. Figs. I, J. Tail cut off by the animal. (See
page 207.)

What appears to be the same species, or a very nearly allied one, was found
by Mr. Hemphill at Cray's Harbor, Washington, on the banks of the Chehalis
River, near its mouth. This form is figured on Plate VIII. Fig. C. When
extended fully, it is 70 millimeters long. It is more slender and more pointed

MUSEUM OF COMPARATIVE ZOOLOGY. 207

at the tail than the large form. The body is a bright yellow, with bluish
black reticulations. The edge of the foot and the foot itself are almost black ;
shield irregularly mottled with fuscous ; the body also is irregularly mottled
with fuscous, and has one broad fuscous band down the centre of the back,
spreading as it joins the mantle, with a narrower band on each side of the
body. The other characters, external and internal, are given below. This
smaller form loses its colors on being placed in spirits, becoming a uniform
dull slate color.

The large Olympia form is surely A Hon foliolatus, Gould, agreeing perfectly
with his description in Vol. II., and with his figure in Vol. III., excepting
that the latter is colored with a deeper red.

Mr. Hemphill writes of it : "I have to record a peculiar habit that is quite
remarkable for this class of animals. When I found the specimen, I noticed
a constriction about one third of the distance between the end of the tail and
the mantle. I placed the specimen in a box with wet moss and leaves, where
it remained for twenty-four hours. When I opened the box to examine the
specimen, I found I had two specimens instead of one. Upon examination of
both I found my large slug had cut off his own tail at the place where I no-
ticed the constriction, and I was further surprised to find the severed tail piece
possessed as much vitality as the other part of the animal. The ends of both
parts at the point of separation were drawn in as if they were undergoing a
healing process. On account of the vitality of the tail piece, I felt greatly
interested to know if a head would be produced from it, and that thus it would
become a separate and distinct individual." The animal on reaching me still
plainly showed the point of separation from its tail. (See Plate VIII. Fig. A.)
The tail piece was in an advanced stage of decomposition. I noticed the con-
striction towards the tail in one of five individuals of Prcyphysaon cmruleum
from Olympia. (See page 209.) Another individual of the same lot had a
truncated tail, having undergone the operation. The edges of the cut were
drawn in like the fingers of a glove.

The tail of the Arion foliolatus having been cut off, I was unable to verify
the presence of a caudal pore from this individual. On the only living one
of the lot from Gray's Harbor, the pore was distinctly visible, and is figured
on Plate VIII. Fig. C. Usually, it seemed more "a conspicuous pit" than a
longitudinal slit, as in Zonites. At one time I distinctly saw a bubble of
mucus exuding from it. It opened and shut, and is still plainly visible on the
same individual, which I have preserved in alcohol and added to the Binney
Collection of American Land Shells in the National Museum at Washington.
Another individual from Seattle plainly shows the pore.

Five specimens of the Gray's Harbor lot had, concealed in the mantle, a
group of particles of white limy matter which it was impossible to remove as
one shell plate. In the large Olympia individual these irregularly disposed
particles of lime, of unequal size, seemed attached to a transparent membranous
plate. With care, I removed this entire, and figure it. It is suboctagonal in
shape (Plate VIII. Fig. B). Under the microscope it appears that the par-

208 BULLETIN OF THE

tides of lime do not cover the whole plate ; at many points they are widely
separated. This aggregation of separate particles is the distinctive character
of the subgenus Prolepis, to which A. foliolatus belongs.1

The genitalia of the large individual from Olympia is figured on Plate IX.
Fig. D. The ovary is tongue-shaped, white, very long and narrow; the oviduct
is greatly convoluted ; the testicle is black in several groups of cceca ; the
vagina is very broad, square at the top with the terminus of the oviduct, and
the duct of the genital bladder entering it side by side ; the genital bladder is
small, oval, on a short narrow duct ; the penis sac is of a shining white color,
apparently without retractor muscle; it is short, very stout, blunt at the upper
end where the extremely long vas deferens enters, and gradually narrowing to
the lower end. ' There are no accessory organs. The external orifice of the
generative organs is behind the right tentacle.

The form from Gray's Harbor (Plate IX. Fig. H) has its generative system
very much the same as described above. The ovary is much shorter and
tipped with brown, and is less tongue-shaped. The penis sac tapers to its
upper end. The vagina is not squarely truncated above. The system much
more nearly resembles that of Prophysaon Andersoni (see Terr. Moll., V.) than
that of the Olympia foliolatus.

The jaw of both forms is very low, wide, slightly arcuate, with ends attenu-
ated and both surfaces closely covered with stout, broad separated ribs, whose
ends squarely denticulate either margin. There are about 16 of these ribs in
one specimen from Gray's Harbor, and over 20 in that of the true foliolatus from
Olympia (see Plate IX. Fig. B). The lingual membrane in each form is long
and narrow, composed of numerous longitudinal rows of about 50-1-50 teeth,
of which about 16 on each side in the true foliolatus (Plate IX. Fig. C), and
19 in the other form, may be called laterals. Centrals tricuspid, laterals
bicuspid, marginals with one long inner stout cutting point, and one outer
short side cutting point. The figure shows a central tooth with its adjacent
first lateral, and four extreme marginals.

I have figured both the true foliolatus from Olympia (Plate VIII. Fig. A)
and the smaller form from Gray's Harbor (Plate VIII. Fig. C) of natural size.
Should the latter prove a distinct species or variety, I would suggest for it the
name of Hemphilli, in honor of the discoverer of it and the long lost foliolatus.

Prophysaon Hemphilli.
See Plate VII. Fig. D, drawn by Cockerell from the living animal.

Prophysaon Andersoni, J. G. Cooper.

Figure 1 of Plate III. was drawn from a specimen received from Dr. Cooper.
It represents the true Andersoni, distinguished by a light dorsal band, and by
genitalia such as I have described for P. Hemphilli. The same form, also re-

1 Mr. Theo. D. A. Cockerell, finding the slug not to be a true Arion, is about to
suggest for it the generic name of Phenacarion.

MUSEUM OF COMPARATIVE ZOOLOGY. 209

ceived from Dr. Cooper, is drawn by Mr. Cockerall on Plate VII. Fig. C. Mr.
Cockerell has shown me that I have confounded with it another species, which
he proposes to call P. fasciatum. See next species.

Prophysaon fasciatum, Cockerell.

This species is described by Mr. Cockerell as distinct from Andersoni, with
which I have formerly confounded it. (2d Suppl. to Vol. V., p. 42.) It has
a dark band on each side of the body, running from the mouth to the foot.
To this must be referred the descriptions of animal, dentition, jaw, and geni-
talia formerly published by me as of Andersoni.

I am indebted to Mr. Theo. D. A. Cockerell for a figure and description of
this species. The former is given on Plate VII. Fig. A, while the latter is
given here in the words of Mr. Cockerell, whose name must consequently be
associated with it as authority : —

Length (in alcohol), 19 mm. Mantle black, with indistinct pale subdorsal bands, —
an effect due to the excessive development of the three dark bands of the mantle.
Body with a blackish dorsal band, commencing broadly behind the mantle and
tapering to tail, and blackish subdorsal bands. No pale dorsal line. Reticulations
on body squarer, smaller, more regular, and more subdivided than in P. Andersoni,
Cooper. Penis sac tapering, slender. Testicle large. Jaw ribbed.

Prophysaon coeruleum, Cockerell.

Plate VIII. Fig. I, J.

In the Nautilus, 1890, p. 112, it is thus described : —

Length (in alcohol), 22| mm. ; in motion, 43 mm. Body and mantle clear blue-
gray, paler at sides, sole white. Mantle finely granulated, broad, without mark-
ings. Length of mantle, 7 mm ; breadth, 5 mm. Respiratory orifice, 24 mm. from
anterior border. Body subcylindrical, tapering, pointed. (In one specimen eaten
off at the end.) Distance from posterior end of mantle to end of body, 10J mm.

The reticulations take the form of longitudinal equidistant lines, occasionally
joined by transverse lines, or coalescing. Sole not differentiated into tracts. Jaw
pale, strongly ribbed. Liver white.

Mr. Binney sends me colored drawings of the living animal ; the neck is long
and white, or very pale. Mr. Binney has examined the jaw and lingual, and finds
them as usual in the genus.

Several specimens were sent from Olympia, Washington, by Mr. Hemphill to
Mr. Binney.

P. coeruleum is an exceedingly distinct species, distinguished at once by its color
and the character of its reticulations.

Prophysaon cceruleum, var. dubium, n. var., Cockerell.

Length (in alcohol), 8 mm. Length of mantle, 4 mm. Distance from posterior
end of mantle to end of body, 3£ mm. Mantle broad, with four bands composed
of coalesced black marbling, very irregular in shape, and running together anteri-
orly. Body dark, tapering. Sole pale, its edges gray. Liver white.

vol. xix. — no. 4. 14

210 BULLETIN OF THE

With the P. cceruleum is a small dark slug, probably a variety of it, but differing
as described above. It will easily be distinguished by its blackish color and the
peculiar markings on the mantle.

Prophysaon Pacificum, Cockerell.

Plate VII. Figs. B, E, F, H.

Mr. Theo. D. A. Cockerell gives the following in the Nautilus of February,
1890, pp. 111-113 : —

Length (in alcohol), 17£ mm. Body and mantle ochrey brown, head and neck
gray. Mantle granulated, rather broad, with a black band on each side not reach-
ing the anterior border; these bands are farthest (2|mm.) apart near the respira-
tory orifice, from which point they converge posteriorly, and anteriorly by the
bending of the band on the right side. Length of mantle, 7| mm. ; breadth, 4 mm.
Respiratory orifice 3£ mm. from anterior border. Body cylindrical, rounded and
very blunt at end, not conspicuously tapering. Distance from posterior end of
mantle to end of body, 8 mm. Body dark grayish-ochre above, with an indistinct
pale dorsal line; sides paler. Reticulation distinct, with indistinct "foliations."
Sole somewhat transversely wrinkled, but not differentiated into tracts.

Jaw dark, strongly curved, blunt at ends, with about ten well-marked ribs (Plate
VII. Fig F). Lingual membrane with about 35-1-35 teeth; centrals tricuspid, the
side cusps very small, laterals bicuspid, marginals with a large sharp straight inner
point and a small outer one. Compared with P. humile the centrals are slightly
shorter and broader. Liver dark gray-brown.

Found by Mr. H. F. Wiekham under logs in ditches by the roadside and damp
places at Victoria, Vancouver Island, 1889.

This is a very distinct species, easily recognized by its color, the absence of dark
bands on the body, the pale dorsal line, and the blunt posterior extremity.

Prophysaon flavum, Cockerell.

Plate Vn. Fig. K.

From the Nautilus, 1890, p. Ill: —

Length (in alcohol). 25 mm. Body and mantle dull ochreous, head and neck
ochreous. Mantle tuberculate-granulose, grayish ochre, pale at edges, and with
black marbling or spots in'place of the bands of P. Pacificum. Length of mantle,
11 mm. ; breadth, 5| mm. Respiratory orifice 5 mm. from anterior border. Body
cylindrical, hardly tapering, and blunt at end. Distance from posterior end of
mantle to end of body, 14 mm. Body dark grayish-ochre above, with a pale
ochreous dorsal line not reaching much more than half its length ; sides paler.
Reticulations distinct, "foliated." Sole with well marked transverse lines or
grooves, those of either side meeting in a longitudinal median groove, which
divides the foot into two portions. Liver pale grayish.

Uniform tawny, as is Umax flams. It stretches itself out in a worm-like shape
unlike other species. Internal shell plate, jaw, and tongue as in Andersoni.

Gray's Harbor, Washington. (Hemphill, 1889.)

This is probably a variety of P. Pacificum.

MUSEUM OF COMPARATIVE ZOOLOGY. 211

Prophysaon humile, Cock ere ll.

Plate VII. Figs. F, G, I., M.

From Nautilus, 1890, p. 112.

Length (in alcohol), 16£ mm. Body above and mantle smoke-color, obscured
by bands. Mantle wrinkled, and having a broad dorsal and two lateral blackish
bands, reducing the ground-color to two obscure pale subdorsal bands. Length of
mantle, 7 mm. ; breadth, 5^ mm. Respiratory orifice 2| mm. from anterior border.
Body subcylindrical, somewhat tapering, rather blunt at end. Distance from pos-
terior end of mantle to end of body, 8 nun. Back with a blackish band reaching a
little more than half its length, and lateral darker blackish bands reaching its
whole length. Reticulations distinct, "foliated." Sole strongly transversely striate-
grooved, but not differentiated into tracts.

Jaw pale, strongly striate, moderately curved, not ribbed. (See Fig. F.) Lingual
membrane long and narrow. Teeth about 35-1-35. Centrals tricuspid, laterals
bicuspid, marginals with a large inner point, and one (sometimes two) small outer
points. Liver pale chocolate.

Found by Mr. H. F. Wickham under the bark of rotten logs in the woods around
Lake Cceur d'Alene, Idaho, 1889.

In its reticulations, and general external characters, this species resembles
P. Andersoni, of which it is possibly a variety.

Hemphillia glandulosa.

(See also p. 216.)

From Olympia and Gray's Harbor, Washington, Mr. Hemphill sent me liv-
ing specimens of this species, both young and mature. Several of the young
had the horn-shaped process to the tail noticed in the original description of
the genus. The shell in these young individuals is very slightly attached, ap-
parently simply by having its posterior margin lightly covered by the mantle.
It often becomes detached. In these young, the mantle is proportionally
smaller, and the neck much longer. I have figured an enlarged view of a
young individual, Plate IV. Fig. D.

Ariolimax l Columbianus, Gould.

Found also by Mr. Hemphill on Santa Cruz Island.

Plate VI. Fig. A, represents the mottled variety, found recently b/ Mr.
Hemphill in the State of Washington. Mr. Cockerell suggests for it the vari-
etal name maculatus. This form shares with the type the peculiar penis sac
(Fig. G) distinguishing it from the next species.

Ariolimax Californicus, Cooper.

See Plate V. Fig. E, for the animal in motion, and a portion of the genital
system (Fig. H), showing variation from that of A. Columbianus.

1 The name should .be Arionilimax.

212 BULLETIN OF THE

Ariolimax Andersorti.

See Plate V. Fig. F, showing the typical specimen in spirits restored.

Ariolimax Hemphilli.

Plate V. Fig. B, G.

A variety macidatus, Cockerell, is figured in B. The Figure G is drawn
from a typical specimen, with the tail, the pore, and the locomotive disk.

Ariolimax niger, J. G. Cooper.

Plate V. Fig. A, gives a lighter-colored form ; Fig. I, the typical form; Fig3.
C and D, the caudal pore.

Triodopsis inflecta, Say.

This has erroneously been quoted from the Pacific Province, at the mouth
of Columbia Eiver. It is difficult to decide what species Middendorff had in
view. His words are thus translated : —

Let it not be objected that Helix clausa up to tins time lias not been discovered
west of the Rocky Mountains. The Northwest Coast of America is almost wholly
unexplored conchologically, and I do not doubt that H. clausa will be there
found, just as I can now assert with reference to //. planorboides. Even the
American authors know this hitherto only from the Ohio and Missouri. Its dis-
tribution nevertheless appears to extend over the whole of Nortli America, since I

have received a great number of specimens of the same through Mr. , from

Sitka, whereby it becomes incorporated with our Russian Fauna. Southwards it
extends to the west coast of America, at least to Upper California, where they
were likewise collected by Mr. . It appears to have undergone no altera-
tion whatsoever, and presents in Sitka a considerable size, as the ordinary repre-
sentations show (up to 22, etc.). Moreover, Binney in the Boston Journal, III.,
Plate XIV., has them copied equally large.

Polygyra Roperi, Pilsbry.

Shell umbilicated, plane above, slightly inflated below, shining, pellucid,

light horn-color, with delicate wrinkles of growth ; spire flattened ; whorls 5|,

scarcely rounded, very regularly increasing, the last flattened

above, abruptly deflected at the aperture, deeply constricted

behind the peristome ; aperture transversely lunar, gaping,

much contracted, tridentate ; peristome thickened, broad,

white, gradually thinning and scarcely reflected at its edge,

and not extending beyond the surface of the whorl, its ends

T approached, joined by a light callus, on which is a heavy

enlarged. wdiite callus bearing a stout, white, broad, blunt, transverse

tooth, slightly curving inward, its basal margin with an erect

conical, short tooth, separated by a small circular sinus from another rather

more deeply seated similar tooth on its upper margin. Umbilicus broad,

MUSEUM OF COMPARATIVE ZOOLOGY. 213

showing the volutions clearly. Greater diameter, 9 mm. ; lesser, 7 mm. ;
height, 2£ mm.

Helix (Triodopsis) Ropen, Pilsbry. The Nautilus, Vol. III. No. 2, June, 1889,
p. 14.

Bedding, Shasta Co., California, in drift of the Sacramento River, three
dead shells were collected by Mr. Edward W. Roper, of Chelsea, Mass.

The above description is drawn from one of the original specimens, kindly
lent me by Mr. Roper, while another in the collection of the Academy of Natu-
ral Sciences of Philadelphia, from which Mr. Pilsbry drew his description, is
figured above. The third specimen was given by Mr. Roper to Mr. Henry E.
Dore of Portland, Oregon.

Never having seen a specimen of P. Harfordiana, I cannot say if this species
is identical with it. At least, it must be nearly allied.

Aglaja fldelis, Gray.

New figures of several forms of this species are given. Plate X. Fig. A
represents the black elevated form approaching infumata. Its sculpturing is
given in Fig. B. The small, black, elevated form is given in Fig. C, with its
sculpturing in D ; the small, depressed form, in E.

Aglaja infumata, Gould.
Plate X. Fig. F, gives an enlarged view of the hirsute surface.

Arionta arrosa, Gould.

Plate XL Fig. A gives this species. A form of arrosa nearly approaching
A. exarata is given in Fig. B, its sculpturing in Fig. C.

Arionta exarata, Pfeiffer.
The typical form and its sculpturing are given on Plate XI. Figs. D and E.

Arionta Mormonum, Pfeiffer.

The typical form is given on Plate XI. Fig. F. The rrpr
variety (Vol. V. p. 141) approaching Aglaja Hillebrandi,
is given in Figs. G and H ; the sculpturing of the same
form, on Plate X. Fig. G. The genitalia of this form
are the same as of the type.

Arionta sequoicola, J- G. Cooper.

A figure of the sculpturing of this species is here ~"EnlarBed sculptnring of
given, greatly enlarged. Arionta sequoicola.

214

BULLETIN OF THE

Arionta Californiensis, Lea.

I give here new figures of two forms of this species, Arionta Diabloensis and
the depressed variety of A. Bridgesi, the former drawn from a shell received
from Dr. Cooper.

Arionta Diabloensis

Arionta Bridgesi, depressed.

Onchidella Carpenteri, Dall.

An alcoholic specimen received from Mr. Dall is figured on Plate VI.
Figs. D, E, enlarged twice.

Veronicella olivacea, Stearns.

I have failed to receive Californian specimens. That figured on Plate IX.
Figs. E, F, is one of the original lot from Folvon, Central America.

CENTRAL PROVINCE SPECIES.

Limax montanus, Ingersoll.

A specimen is figured on Plate VIII. Fig. G.
The species is surely identical with L. campestris.

Patula solitaria, Say.

Mr. Hemphill found this species very abundant at Old Mission, Coeur
d'Alene, Idaho. There was an albino variety, a depressed form, and one very
much more elevated than that which I figured in the Second Supplement,
Plate I. Fig. 10.

MUSEUM OF COMPARATIVE ZOOLOGY.

215

P. strigosa, var. subcarinata,
Hemphill.

See the

Patula strigosa.

Among the shells recently collected by Mr. Hemp-
hill at Old Mission, Coeur d'Alene, Idaho, was a
marked variety of this species, for which Mr. Hemp-
hill suggests the name subcarinata. The specimens
vary greatly in elevation of the spire, and in the num-
ber and disposition of the revolving bands, often
quite wanting. All have a very heavy shell, the body
whorl of which has an obsolete carina which is well
marked at the aperture, modifying the peristome very decidedly,
figure.

In examining the genitalia I find the base of the duct of the genital bladder
greatly swollen along a fifth of the total length of the duct.

On the banks of the Salmon River, Idaho, Mr. Hemphill found a form like
var. Gouldi, but distinctly carinated. None of the Utah
individuals of this form are so characterized.

Another form of strigosa from the same locality is very
large, flat, with a transversely oval aperture, the ends of the
peristome so nearly approached as almost to touch, and
often joined by a heavy callus, which forms a continuous
rim around the aperture. Mr. Hemphill has called this
var. jugalis.

Patula strigosa, var ju
galis, Hemphill.

Microphysa pygmaea.

Found by Mr. Hemphill at Old Mission, Cceur d'Alene,
Idaho.

Microphysa Ingersolli, inland.

A better figure of this species is here given.

Triodopsis Hemphilli.

Mr. Tryon has suggested the name binom-
inata for this species, though Hemphilli is
not preoccupied in Triodopsis.

Microphysa Inger-
solli, enlarged.

Triodopsis Sanburni,
enlarged.

Triodopsis Sanburni.

The cut is drawn from one of the original specimens.

Mesodon ptychophorus.

At Old Mission, Cceur d'Alene, Idaho, Mr. Hemphill found
a form of this species characterized by a heavy, dead white
shell with scarcely any trace of ribs or wrinkles of growth
which are usually so characteristic of the species. On the
banks of the Salmon River he found a small form, the lesser
diameter of which is only 12 mm. See figure.

Mesodon ptycho-
phorus, var.

216 BULLETIN OF THE

Triodopsis Harfordiana.

Ancey suggests commutanda, and Tryon Salmonensis, as a substitute for the
name Harfordiana. I retain the last name, it not being preoccupied in the
genus Triodopsis.

Prophysaon Andersoni?

Specimens collected by Mr. Hemphill at Old Mission, Coeur d'Alene, Idaho,
appear to agree with specimens of this species received from Dr. Cooper. The
jaw is low, wide, slightly arcuate, with over 12 broad, stout ribs, denticulating
either margin. The lingual membrane is given in Plate II. Fig. 2. The
central and lateral teeth are slender and graceful. The latter have, apparently,
a second inner cutting point, as is found in Limax agrestis. I have so figured
it, hoping to draw attention to it, and thus settle the question of its being
there.

Hemphillia.

Plate IV.

From Old Mission, Cceur d'Alene, Idaho, Mr. Henry Hemphill has sent me
fine large specimens of Hempliillia alive. From these I am able to give the
outward characteristics of the animal in drawings by Mr. Arthur F. Gray.

The animals are larger and much lighter in color than those originally found
at Astoria. They do not while in motion differ from other slugs, though my
former figure of the animal in spirits shows a very great difference, owing to
the contraction being resisted by the internal shell. The rear end of the mantle
seems swollen and blunt, separated from the back, however, and thus alone
does there seem to me any difference in its appearance from Limax, whose
mantle lies fiat upon the back. The slit in the mantle is sometimes open,
sometimes closed, and the slit seems to extend quite to the rear of the mantle.
There is a profuse flow of mucus from over the slit. There seem on the man-
tle to be little protuberances, rather than the elongated reticulation of the
rest of the animal. The caudal pore opens and shuts, and exudes mucus in
bubbles sometimes, which occasionally form a solid lump of mucus on the tail.
The horn-like process of the tail so prominent in the first specimens from
Astoria — contracted in alcohol — does not exist in these living specimens,
though occasionally there is a kind of hump above the pore. (See Plate IV.
Fig. D.)

Mr. Hemphill writes : " Hemphillia has a peculiar habit when removed from
its resting place of switching its tail, so to speak, cprite rapidly, — a habit I
never noticed in any of our other slugs. I find them hibernating in old
rotten logs."

The viscera are enclosed under the mantle.

Mr. Gray in drawing the animal called ray attention thus to the characters
of the outward markings of the slug : —

MUSEUM OF COMPARATIVE ZOOLOGY. 217

" You are right in saying that the slit in the mantle extends to the back margin.
The central pit seems flooded with mucus at all times, but does not change its
form ; the slit, however, seems to widen and show a little ridge on either margin
when the animal is fully expanded. The little tubercles, or small pimples as it
were, seem to cover the posterior portion of the mantle, while the elongated tuber-
cles seem to cover the anterior half, though these at times disappear and the ante-
rior portion runs into folds, which break up the surface, and starting from the
margin of the mantle run to its centre in parallel lines like miniature waves.
They move steadily inward from both margins, disappearing before reaching the
little mucous pit in the centre of the mantle, little wavelets rising at the margins
and keeping up a constant rhythmic motion toward the centre."

The jaw of this specimen has about 25 ribs, denticulating either margin. It
is low, wide, slightly arcuate, with slightly attenuated ends. (See Plate IX.
Fig. A.)

The lingual membrane is as described and figured by me in Vol. V. ; tbere
are, however, in this form, 57-1-57 teeth, with some eleven true laterals.

The genitalia I have figured in Plate III. Fig. 3. It agrees with my figures
in Vol. V. of the genitalia of the original specimens, excepting that the penis
sac, as represented there in Plate XII. Fig. K, is here doubled on itself.

Pupa hordeacea, Gabb.

An authentic specimen of this species is figured in the Second Supplement,
Plate III. Fig. 10, referred by mistake to P. Arizonensis in the explanation of
Plate III.

Pupa Arizonensis, Gabb.

The reference to hebes in Second Supplement should be Fig. 12, not Fig. 10.

LOCALLY INTRODUCED SPECIES.

Tachea nemoralis, Linn.

Fine large specimens of this species have been sent me by Prof. James H.
Morrison, found by him living during the last three years at Lexington, Vir-
ginia. They form part, no doubt, of a colony descended from living individ-
uals introduced from Europe around plants.

Zonites cellarius, Muller.

Also at San Francisco (Cooper).

Limax maximus, Linn.

Also at New Braunfels, Texas (Singerly).

A drawing of the lingual dentition on Plate II. Fig. 1, shows the cutting
points of central and lateral teeth to be trifid. This is not shown in my figure
in Vol. V.

218 BULLETIN OF THE

Since the foregoing was written, the following species have been de-
scribed : —

Zonites selenitoides, Pilsbrt.

This species is similar in form and general appearance to Z. minusculus, Binn.,
though decidedly larger. The umbilicus is broad, as in the latter species. The
shell is thin, light yellowish horn-color, almost white. Surface
shining, covered with close strong oblique rib-strise, like Patula
striatella; these stria?, while generally regular, sometimes bifurcate,
or separate to give room for another to be inter-
calated. The spire is flatter than minusculus, nearly ?1
plane. The earlier If to 2 whorls are smooth, pol- f]
ished, not striate ; the sutures are well impressed.

There are 3£ whorls in all, convex, gradually widen-
Zotntes Bclenitoi- . . * . Sculpturing, en-

des, enlarged. in£> tne 'ast proportionately wider than in Z. minus- larged

cuius. Aperture slightly oblique, lunate, narrower
than in Z. minusculus, its margins thin, acute, scarcely converging, the columellar
shortly subreflexed.

Alt. 1.2 mm., diam. 3 mm.

The specimens were presented to me by Mr. W. G. Binney, who, regarding them
as new, kindly permitted me to describe them. They were gathered by Hemphill,
prince of collectors ! at Mariposa Big Trees, California. The name selenitoides is
given because of a certain resemblance to the little Seknites Duranti of Southern
California.

The above description was published by Pilsbry in Proceedings of Academy
of Natural Sciences of Philadelphia, 1889, p. 413, Plate XII. Figs. 13-15.
I give a figure of the original specimen, and of its sculpturing.

Zonites Simpsoni, Pilsbry.

This species belongs to that group of Ilyalina comprising capsella, Gld., Laicce,
W. G. Binn., and placentula, Shutt., — species with narrow umbilicus, numerous
closely coiled narrow whorls, and without a callus or thickening within the base
of the last whorl. Z. Simpsoni differs from placentula in its much smaller size,
nearly straight, instead of arcuate, basal lip, seen from beneath, proportionately
wider last whorl, and the more trigonal, wider aperture. With Z. Lawce I need not
compare it, as that species is much larger and more elevated. Z. capsella is about
the same size, color, and texture as Simpsoni, but has a narrow umbilicus and
very much narrower aperture, narrowly semilunar instead of trigonal in outline.
Z. Simpsoni has 5 whorls. Alt. 2, diam. maj. 4^, min. 4 mm.

The specimens before me were collected by Mr. C. T. Simpson, at Limestone-
Gap, Indian Territory. The trigonal form of the aperture is so peculiar that the
species may be separated from Z. capsella. at a glance. My comparisons were made
with specimens of capsella received from Gould, and placentula from W. G. Binney.
The figures are camera lucida drawings.

From Proc. Acad. Nat. Sci. Phila., 1889, p. 412, Plate XII. Figs. 8-10.

MUSEUM OF COMPARATIVE ZOOLOGY. 219

Pupa calamitosa, Pilsbrt.

Shell minute, cylindrical, very blunt at apex, chestnut-colored ; whorls 4^, the
first one and a half smooth, the following regularly costulate striate, the costulae
separated by spaces wider than themselves ; last whorl abruptly turning forward,
rounded beneath, encircled by a slight central constriction or furrow ; aperture
about one third the total length of shell, rounded, truncated above, contracted
within; peristome thin, expanded, without crest or callous thickening behind;
columellar margin rather dilated ; parietal wall bearing two entering lamella?, one
arising near the termination of the outer lip, the other more deep seated, elevated,
entering less obliquely ; columella with a strong white deep-seated obliquely enter-
ing fold ; outer lip with two short white lamellae.

Alt. 1.70, diam. 0.80 mm.

Two trays of this. tiny species are before me. One received from Henry Hemp-
hill, collected near the mouth of San Tomas River, Lower California, the other
collected by Orcutt near San Diego, California. Most specimens show the widen-
ing inward of the outer lip shown in the figure. Several specimens have only one
lamella on the outer lip, and are rather larger than the typical form described,
measuring 1.90 mm. alt. The second parietal lamella is usually much larger than
the first, but in one or two specimens before me this is not the case. The umbili-
cal rimation terminates in a tiny depression, perhaps minutely perforated at the
axis. The formula of denticles or folds (according to Dr. Sterki's scheme1)
AA B D E or AA B E. The species is of a decidedly different type from any
known American Pupa. P. hordacea, Californtca, and Rowelli, abundant Western
forms, belong in quite diverse groups ; the first being allied to P. corticaria and
pellucida, the last two grouping with P. decora, Rowelli, and corpulenta.

From the Pupa, of the Mexican fauna, leucodon, pellucida, and chordata, the pres-
ent species is quite distinct in every respect.

The inward continuation of the parietal and columellar folds is shown in Figure
17. They are white, regularly veined with darker, like polished plates of agate.

From Proc. Acad. Nat. Sci. Phila., 1889, p. 411, Plate XII. Figs. 16, 17.

Mr. Hemphill sends me the following descriptions, which must be fully
credited to him ; —

Helix tudiculata, var. Binneyi.

This beautiful variety belongs to the globosely depressed forms of H. tudicu-
lata, Binn. It is of a uniform greenish yellow color, without blotches or
markings, except a very faint trace of a band at the periphery. H. tudiculata
is very variable in form, size, and sculpture, and with the umbilicus either
open or closed, but it is very constant in its dark chestnut-color in Southern
California. North of Merced County, however, it becomes a shade lighter,
and passes towards the light, thin form of H. arrosa, which I regard as the

1 See Proc. U. S. Nat. Mus., 1888, p. 369. I have repeated the letter presenting
the parietal fold, as the two seem to be of equal importance.

220 BULLETIN OF THE

progenitor of tudiculata, arrosa in turn having evolved from its northern
neighbor, H. Townsendiana, Lea, and Townsendiana from the form we now
call H. ptychophorus, Brown, found in Eastern Oregon and Idaho.

Habitat. Mountains of San Diego County, California. Only one specimen
found.

Helicodiscus fimbriatus, var. Salmonensis.

This variety varies from the Eastern or typical forms in the absence of the
revolving lines; otherwise the shells are alike.

Habitat. Banks of Salmon River, Idaho, Old Mission, Idaho, and Oakland,
California.

Helix Kelletti, var. albida.

This is a beautiful clear white translucent variety, with no markings or
stains of any kind. It is quite thin and frail, and a trifle smaller than the
average size of Kelletti.

Habitat. Santa Catalina Island, California. Two specimens only found-
by me.

Helix Kelletti, var. castanea.

Among the numerous patterns of coloring assumed by H. Kelletti, none are
more conspicuous than this well marked variety. The body whorl is of a
deep shiny chestnut-color above the periphery, and becomes lighter as it fol-
lows the whorls of the spire to the apex. The band at the periphery is quite
variable in the different speeimens ; it is generally light, and well defined
above, but below it is irregular and spreads over the base of the shell more
or less.

Habitat. Santa Catalina Island, California. This variety is not rare.

Patula strigosa, var. Buttonii.

Shell umbilicated, elevated, or moderately depressed, nearly white, some-
times stained with light chocolate; whorls five, convex, with numerous oblique
striee ; suture impressed, aperture circular ; peristome thickened, not reflected,
darker than the body of the shell; extremities nearly approached and joined
by a callus ; with or without a basal tooth ; tooth when present very variable,
generally consisting of a single tubercle ; in some specimens it is nearly or
quite square, as high as long ; in other specimens it is long and bifid.

Diameter of the largest specimen, f- inch ; height, \ inch. Diameter of the
smallest specimen, \ inch ; height, f inch.

Habitat. Box Elder Co., Utah.

I dedicate this interesting form of strigosa to my friend, Mr. 0. Button, of
Oakland, California.

MUSEUM OF COMPARATIVE ZOOLOGY. 221

Selenites Duranti, var. Catalinensis.

Shell widely umbilicate, depressed, white, transparent when fresh ; whorls
4, flattened above and below, with fine oblique striae ; spire plauulate ; aper-
ture transversely rounded ; peristome simple, acute ; extremities approached
and joined by a very thin callus in fully matured specimens.

Greatest diameter, \ inch ; height, ^ inch.

Habitat. Santa Catalina Island, California.

My little shell differs from the typical Duranti in its greater size, smoother
surface, broader umbilicus in specimens of the same size, but principally in its
transparent shining surface. It is larger than the largest Duranti that I have
8een, but not so large as the costate variety of that species described by Mr.
Mazyck as distinct under the name of S. ccelata, which I have in my possession.
My specimen of that species is larger than his measurements.

I can add the following to his locality : Los Angeles and San Diego, Cali-
fornia, Point Abunda, and banks of San Tomas River, Lower California; thus
giving it a range of about two hundred miles up and down the coast. I have
collected the typical S. Duranti at the following places : Etna Springs, Napa
Co., Healdsburg, Sonoma Co., Bolinas and San Rafael, Marin Co., Oakland,
Alameda Co., Santa Cruz, Monterey, Santa Barbara Island, Santa Catalina
Island, and San Clemente Island, a range of over one hundred miles north
and south. It is confined to the Coast Range as far as we know at present.

222 BULLETIN OF THE

EXPLANATION OF THE PLATES.

PLATE I

Fig. 1. Central tootli of lingual membrane of Mesodon major, the specimen la-
belled A (see p. 190).
Fig. 2. Central tooth, two adjoining lateral teeth, and two marginal teeth of lin-
gual membrane of Mesodon major, the specimen labelled B (see p. 190).
Fig. 3. Same : an outer lateral tooth bearing a side cusp and cutting point (see

p. 190).
Fig. 4. Mesodon Andrewsi : the genitalia.

ov. oviduct.

g. b. genital bladder.

d. g. b. duct of same.

v. d. vas deferens.

r. retractor muscle of penis sac.

p. s. penis sac.

or. common orifice.

p. prostate gland.
Fig. 5. Penis sac of another specimen of same.
Fig. 7. Lingual dentition of same, from specimen labelled E. Two central teeth,

with an adjoining lateral tooth.
Fig. 8. Same : marginal teeth.
Fig. 9. Same : extreme marginal teeth.

Fig. 10. Same : first lateral tooth of specimen labelled F (see p. 191).
Fig. 11. Same: marginal tooth (see p. 191).

Fig. 12. Same: specimen labelled M (see p. 191), an outer lateral tooth.
Fig. 13. The fourth lateral tooth of Limax Hemphilh (see p. 205).
F"ig. 14. Succinea chri/sis, Westerlund, copied from the " Vega Expedition," Plate

III. Fig. 10.
Fig. 15. Succinea annexa, Westerlund, copied from the same, Fig. 11.

PLATE II.

Lingual dentition of: —
Fig. 1. Limax maximus. A central tooth with two adjacent laterals; an outer

lateral ; two marginals, the left hand one the last.
Fig. 2. Prophysaon (see p. 216). A central tooth with its adjacent lateral tooth ;

an outer lateral tooth ; an extreme marginal tooth.

MUSEUM OF COMPARATIVE ZOOLOGY. 223

Fig. 3. Limaz Hemphilli. A central tooth with two adjacent laterals ; an outer

lateral tooth ; two outer marginal teeth.
Fig. 4. Limax Hewstoni. A central tooth with adjacent lateral on either side;

incorrectly numbered on the plate ; two extreme marginals.
Fig. 5. Microphysa dioscoricola (see p. 196).

PLATE III.

Fig. 1. Prophysaon Andersoni, J. G. C, received from Dr. Cooper.
Fig. 2. Pupilla Floridana, Dall, from original figure.

Fig. 3. Genitalia of Hemphillia, from Old Mission, Coeur d'Alene, Idaho (see
p. 217):-

t. testicle.

ep. epididymis.

ov. ovary.

ovid. oviduct.

pr. prostate.

g. b. genital bladder.

d.g. b. duct of same.

v. d. vas deferens.

r. retractor muscle of penis.

p. s. penis sac.

or. common orifice.
Fig. 4. Helix exigua, from an original drawing by Dr. Stimpson.
Fig. 5. Zonites lasmodon, Phillips, enlarged. Drawn by Miss Helen E. Lawson.
Fig. 6. Central portion of jaw of Microphysa dioscoricola, greatly enlarged.
Fig. 7. Bulimus Floridanus (see p. 201). Drawn from original specimen in Mr.

Cumings's collection, by G. B. Sowerby.
Fig. 8. Lingual dentition of Polygyra hippocrepis.

a. central and two lateral teeth.

b. marginal teeth.
Fig. 9. Bulimus Hemphilli.

Fig. 10. Dentition of Onchidium Floridanum.

PLATE IV.

Fig. D was drawn by W. G. Binney, the other figures by Arthur F. Gray : all
from life.

Fig. A. Hemphillia glandidosa, twice the natural size.

Fig. B. The same; animal in motion, natural size; the slit on the mantle par-
tially open.

Fig. C. The same; partially contracted and at rest.

Fig. D. The same; the very young animal.

Fig. E. The same; dorsal view of posterior portion of the animal, twice the nat-
ural size ; pore closed

Fig. F. The same ; lateral view, pore closed.

224 BULLETIN OF THE

Fig. G. The same; dorsal view, pore open.

a. mucus beads exuding.

b. slit, widely opened, the walls or lips rolled out.

c. mucus accumulations.

Fig. H. The same ; lateral view, pore open.

Fig. I. The same as last.

rig. J. The same; the internal shell plate.

PLATE V.

Figs. F, H, drawn by W. G. Binney ; A, C, D, by Arthur F. Gray ; B, E, G, I,
by T. D. A. Cockerell, of West Cliff, Custer Co., Colorado: all from life.
Fig. A. Ariolimax niyer, fully extended.

Fig. B. Ariolimax Hemphilli, var. maculutus, Cockerell; animal contracted in alcohol.
Fig. C. Ariolimax niger ; the caudal mucus pore, twice the natural size, dorsal
view, the pore open.

a. mucus exuding.

b. b. ridges each side of slit or channel.

c. mucus channel or pore.

d. little channels conducting mucus from back of animal into channel c.
Fig. D. The same ; posterior view.

Fig. E. Ariolimax Californicus, in motion, natural size.
Fig. F. Ariolimax Andersoni, restored from an alcoholic specimen.
Fig. G. Ariolimax Hemphilli, in motion, with end of tail and pore.
Fig. H. Portion of genitalia of E.

p. s. the penis sac.
f. the flagellum.

r. the retractor muscle.

v. d. the vas deferens.
Fig. I. Ariolimax niger, partially extended.

PLATE VI.

Figures B, C, D, E, H, were drawn by A M. Baldwin, the last from life, the
others from specimens preserved in spirits ; Figures F, G, by W. G. Binney, from
life; A, from life, by Arthur F. Gray.

Fig. A. Ariolimax Columbianus, var. maculatus, Cockerell, natural size ; from a

specimen collected by Mr. Hemphill.
Fig. B, C. Onchidium Floridanum, three times natural size ; from type.
Fig. D, E. Onchxde.Ua Carpmteri, twice natural size.
Fig. F. Tebennophorus Wetherbyi ; from type.

Fig. G. Portion of genitalia of A.

p. s. the penis sac.

r. the retractor of same.

v. d. the vas deferens.
Fig. H. Tebennophorus Hemphilli; from the type.

MUSEUM OF COMPARATIVE ZOOLOGY. 225

PLATE VIL

All the figures drawn by T. D. A. Cockerell, excepting I, which was drawn by
Miss Annie Roberts.

Fig. A. J

°roph

ijsaon

fasciatum.

Fig. B.

it

Pacijicum.

Fig. C.

tt

Andersoni.

Fig D.

t<

Hemphilli.

Fig. E.

tt

pacijicum, jaw

Fig. F.

tt

humile, jaw.

Fig. G

a

" the animal contracted in spirits, and the surface

Fig. H.

a

Pacijicum; the same views as last.

Fig. I.

u

cceruleum.

Fig. J.

tt

tt

Fig K.

tt

flavum.

Fig. L.

it

humile.

Fig. M.

it

a

PLATE VIII.

Figure C was drawn by F. W. Earl, from life; A, from life, by W. G. Binney;
B, D, G, I, from life, by T. D A. Cockerell ; E, F, H, were restored by Mr, Cock-
erell from specimen in spirits

Fig. A. Phe nacar ion full olatus, natural size ; the tail eaten off.

Fig. B. Internal shell of A.

Fig. C. The same, var. Hemphilli, natural size.

Fig. D. Limax Hewstoni ; in motion and at rest."

Fig. E. " Hemphilli ; same views as last, and surface

Fig. F. " hyperboreus ; same views as last.

Fig. G. " montanus ; same views.

Fig H. " occidentalis ; same views.

Fig. I. " Hewstoni ; a larger individual.

PLATE IX.

Figures A, B, C, D, G, H, were drawn y W. G. Binney ; E, F, by T. D. A.
Cockerell; I, J, by Arthur F. Gray.

Fig. A. Jaw of Hemphillia r/Iandulosa.

Fig. B. Jaw of Phenacarion foliolatus.

Fig. C. Lingual membrane of same ; one central tooth, with its adjacent lateral

and three extreme marginals.
Fig. D. Genitalia of same ; one half of natural size.

ov. ovary.

ovid. oviduct.

t. testicle.

g, b. genital bladder.

p. s. penis sac.

v. d. vas deferens.

226 BULLETIN OF THE MUSEUM OF COMPARATIVE ZOOLOGY.

Fig. E, F. Veronicella olivacea, from one of original lot from Folvon.

Fig. G. Lingual membrane of Glandina decussatu.

Fig. H. Genitalia of P 'he nucurion Jul 'iolut us, var. Hemphilli; same references as in

D ; one half of natural size.
Fig. I. PropJiysaon A*udersoni ; surface magnified sixteen times.

a. a. a. reticulations of tlie body.

6, b. foliolated spaces between reticulations.

c. lower edge of the body.

d. locomotive disk.

Fig. J. The same, magnified eight diameters ; upper surface ; same references

as the last.

PLATE X.

Drawn by A. H. Baldwin, Smithsonian Institution.

Fig. A. Aglaja Jidelis ; the large, elevated black variety.

Fig. B. Sculpturing of same.

Fig. C. The same; small, black, elevated form.

Fig. D. Sculpturing of last.

Fig. E The same ; small, depressed form.

Fig. F. Aglaja infumata; sculpturing.

Fig. G. Arionta Mormonum ; sculpturing of the form figured on Plate XI. Figs. G, H.

PLATE XI.

Drawn by A. H. Baldwin.

Fig. A. Arionta arrosa.

Fig. B. Variety of last, approaching A. exarata.

Fig. C. Sculpturing of last.

Fig. D. Arionta erarata ; type.

Fig. E. Sculpturing of last.

Fig. F. Arionta Mormonum.

Fig. G, H. Variety of last, connecting with Hillebrandi.

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Harvard MCZ Librai

2044 066 300 443