GUIDES FOR VERTEBRATE DISSECTION

NECTURUS

AN URODELE AMPHIBIAN

BY

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GUIDES FOR VERTEBRATE DISSECTION

NECTURUS

AN URODELE AMPHIBIAN

BY

J. S. KINGSLEY

Professor qf Biology in Tufts

NEW YORK
HENRY HOLT AND COMPANY

Copyright, 1907,

BY
HENRY HOLT AND COMPANY

INTRODUCTION

THESE directions for dissection are intended eventually to
include representatives of all the major groups of vertebrates.
Each is complete in itself and is issued separately so that
laboratories may select those forms best adapted for their courses.
The directions have been tested by several years' use and are
thought to have a distinct pedagogic value in that they do not
so much tell the student what he will find, but instead ask him
what he does find. He thus obtains his information from the
specimen, not from the printed page. For similar reasons illus-
trations have been omitted; students sometimes find it easier
to copy the published figure than to work out the points for
themselves.

No attempt has been made to follow out every system of
organs completely, but each has been traced far enough to give
a good knowledge of the more important structures to use as a
basis for comparisons. The student by following the directions
may obtain a knowledge of the general anatomy of the animal
studied, but this knowledge of itself has little value. More
important is the benefit to be gained by comparing the different
forms dissected, tracing as far as possible their resemblances and
differences. Hence in his dissection the student should con-
tinually recall the conditions existing in all other animals as he
is tracing out each part.

More than this: he should read the general statements given
in manuals of vertebrate structure as he takes up each organ
or system of organs, thus correlating his discoveries and making
them a part of one general whole. It would be well to go farther
and read the accounts of the development of the organs in
question in some of the text-books of vertebrate embryology. It
is only in this way that an explanation of many peculiarities of
structure may be obtained.

Unless explicitly used otherwise the terms right and left in
the following directions apply to the right and left of the animal
being dissected, not of the student. Anterior and posterior

111

>

iv INTRODUCTION

indicate relative position with regard to head and tail, while
dorsal and ventral are used for the anterior and posterior of
human anatomy. Medial is used to imply proximity to the
middle line, lateral being the contrasting term. Proximal refers
to that part of an organ or structure nearest to its centre or to
its attachment to the body, distal being the opposite adjective.
In speaking of muscles the fixed point of attachment is the
origin, the attachment on the part to be moved is its insertion.
INJECTING. — In many cases it is almost impossible for the
beginner to trace the blood-vessels unless they are filled with some
colored substance which renders them more easily seen. This
is especially true of the smaller vessels. Injection is also frequently
convenient in tracing other vessels like those of the urogenital
system.

Various substances ('injection masses') have been devised for
filling the vessels. The essential features of a mass are that it
have color, that it flow freely when injected, and that it soon harden
so that it will not escape from a vessel accidentally cut. Within
recent years a starch mass has been largely used, and as this answers
all the purposes of these guides it is described here:

Corn-starch 400 pts. by volume

2% chloral hydrate hi water 400 ' '

95% alcohol 100 "

Color and glycerin (equal parts) . . 100 "
The mixture should be thoroughly mixed by stirring and
strained through cheese-cloth or paper cambric, stirring during
the operation. The starch and color quickly settle, hence the
mixture has to be stirred while using. It will keep indefinitely,
but of course must be thoroughly mixed each time before using.

The colors commonly used are vermillion,* insoluble Prussian
blue, chrome green, and chrome yellow. The vermillion is usually
used for the arterial, the blue for the venous system, but it is
often advantageous to use chrome yellow instead of blue, as it
contrasts better with dark organs like the liver and kidneys, while,
when a blood-vessel occasionally bursts in injection, the viscera
are not so badly stained.

* Care should be taken to get true vermillion (mercuric sulphide), as much
that masquerades under that name is red lead colored with cosine. This
works disadv:int:if!;eously as the cosine dissolves in the liquids in which the
specimens are pre-ervcd and stains everything indiseriminaU'ly.

INTRODUCTION V

An extremely fine chrome yellow may be made by dissolving
200 parts of acetate of lead and 105 parts by weight of chromate
of potash in separate dishes of water. After complete solution
mix and allow the precipitate to settle. Pour off the supernatant
fluid and wash the precipitate with several waters so as to remove
the potassium acetate which would injure the specimen.

Many instruments — syringes, water-pressure apparatus, etc.,
have been proposed for injecting, but a considerable experience
has led to the conclusion that for small animals there is nothing
better than a large rubber bulb for the pressure. This is con-
nected by rubber tubing with the canula which is inserted in the
vessel to be filled. Use the largest canula possible and keep it
free from precipitated mass.

SKELETONS. — The skeletons made by the average student are
likely to be imperfect, but the knowledge which he obtains in.
preparing them is of value. The laboratory should have skeletons
well prepared, but the student should clean those which he studies.
In the case of fishes it is sufficient to remove the skin from the
body, next to place the animal for a few minutes in water
near the boiling-point, and then to remove the flesh by hand.
With other animals the tissues are more resistant, and in these
cases the animal, after removal of the skin, should be boiled in a
soap solution made as follows :

Thoroughly mix with heat 75 grams of hard soap, 12 grams
of potassic nitrate (saltpetre), 150 cc. of strong ammonia, and
2000 cc. of soft water. For use, one part of this 'stock' is diluted
with three of water and the body is boiled in this, the length of
time varying with the size and consistency of the animal, care
being taken not to boil it long enough to soften the ligaments
unless it be desired to separate the bones from each other.

For decalcification of skull* in order easily to get at the
brains, nitric alcohol, made by mixing equal parts of ten per cent
nitric acid and ninety-five per cent alcohol, is useful.

Material for dissection can be obtained from

Supply Department, Marine Biological Laboratory, Woods

Hole, Mass.

Dr. F. D. Lambert, Tufts College, Mass.
H. H. and C. S. Brimley, Raleigh, N. C.
H. A. Ward, Rochester, N. Y.
Kny-Scheerer Co., 225 Fourth Ave., New York.

NECTURUS

Necturus or Menobranchus, commonly called the mud-puppy,
is distributed through the Mississippi and St. Lawrence basins,
from whence it has found its way in recent years into other
waters (the Hudson at Albany, etc.). Where it occurs it may
be taken with hook and line, but it is better to capture it with
nets or seines, on account of its habit of swallowing the hook.

Two specimens, a male and a female, besides a prepared
skeleton, will be required by each student. One of the specimens,
preferably the male, should be injected. The injection is best
accomplished in the following order: First, with blue, inject
forwards and backwards through the hepatic vein at the base of
the liver, filling the heart, postcava, and the branches in the
liver. Next, with red, into the dorsal aorta in both directions
at about the middle of the ccelom. The postcava being already
filled with blue, the aorta is more readily seen. Lastly insert the
canula into the portal vein just before its entrance into the liver,
and inject with blue forwards and backwards.

The preparation of the skeleton is a more difficult matter
than with some animals, especially in the caudal region. Skele-
tons good enough for study purposes may be made by boiling with
soap solution, following this by picking away the flesh with the
forceps and finishing by careful brushing with a tooth-brush.
The boiling should not be too prolonged because of the danger
of separation of the parts. When not in use the skeletons should
be kept in alcohol, but when studied they should be soaked in
water, which swells the cartilages and restores them to their
normal condition. The female specimen can be used for skeletal
purposes after the urogenitals have been studied.

GUIDES FOR VERTEBRATE DISSECTION

EXTERNAL FEATURES

How many regions — head, neck, trunk, tail, etc. — can you
distinguish? Do you find any indications of scales on or in the
skin? Do you find any median or paired fins? Are any of them
supported by fin-rays? Is the tail diphy-, homo-, or heterocer-
cal? * Where is the anus?

Examine the head for nostrils, eyes, ears, mouth, etc., noting
the position of each. Is the mouth wide or narrow? Terminal
or inferior in position? Are lips present? Are there any eye-
lids? Probe with a bristle through the nostril (external nans)
and note the position of the opening (choana or internal nans)
where it enters the mouth.

How many external gills do you find? Look between them
for gill-slits (visceral or branchial clefts); how many on each
side? How many pairs of legs occur? Can you find in each
the same regions — thigh, upper arm, shank, forearm, ankle,
wrist, etc. — as occur in your limbs? How many toes in each
foot? Note the peculiar way in which the limbs stand out at
nearly right angles to the body. Make out in each a dorsal and
a ventral surface, an anterior, or preaxial, and a posterior, or
postaxial, side.

In the trunk region notice the impression of the muscle-
plates upon the skin. How many plates can be counted between
fore and hind limbs?

Draw a side view of the animal, natural size, labelling the
parts.

INTERNAL STRUCTURE

I. MUSCULAR SYSTEM

REMOVE the skin from the head and trunk by cutting down
the middle line of the back and then skinning laterally until the
whole is free. Take great care not to injure the underlying
muscles. The external gills need not be removed with the skin.

* Diphyccrcal, tail alike above and In-low, the parts symmetrically
arranged around the vertebral column; horaocercal, the upper and lower
lobes of the tail alike, the vertebral column extending into the upper lobe;
heterocercal, the lobes unequal, the vertebral column extending into the
upper lobe.

NECTURUS 3

Muscles of the Head and Visceral Arches. — Examine the lower
side of the head, making out the following muscles and sketching
each as you proceed.

(1) The mylohyoid muscle extends across the ventral surface
of the lower jaw, its fibres running transversely. Can you dis-
tinguish any differences between its anterior and posterior
portions, in their mode of attachment to the halves (rami) of the
jaw? Cut the mylohyoid across in the median line, turn the
halves back and see beneath

(2) The geniohyoid muscle, attached in front to the sym-
physis (tip) of the lower jaw and behind to the ventral fascia
(see below) of the region of the neck, its fibres running at right
angles to those of the mylohyoid.

Attached at about the middle of the geniohyoid on either
side is (3) an external ceratohyoid muscle which runs obliquely
outwards and backwards. Follow it towards the dorsal side:
how far does it extend? and where is its insertion? To answer
this last question it will be necessary to remove a fan-shaped
muscle, (4) the levator branchiarum, from the side of the neck,
which is attached at its smaller end to the region of the gills.
The external ceratohyoid pulls the gills forward, the levator
lifts their bases.

On the dorsal surface of the head are a pair of (5) temporalis
muscles, the line separating them continuing back the length of
the body. In what direction do the temporalis muscles run?

Lateral to each temporalis is (6) a large masseter muscle,
which has its origin from the posterior and lateral regions of the
skull. Its fibres run parallel to the external ceratohyoid, to be
inserted on the lower jaw at the angle of the mouth.

Separate the masseter and the external ceratohyoid with the
handle of the scalpel and cut across the levator branchiarum,
exposing the small underlying muscle, (7) the levator arcuum
branchiarum, which arises from the posterior part of the cranium
and is inserted on the branchial cartilages at the base of the
external gills.

. Lateral and anterior to the levator arcuum is (8) the depressor
mandibulse, or digastric muscle, of about equal size. It is at-
tached at one end to the cranium, and its fibres, running parallel
to those of the external ceratohyoid, are inserted upon the angle
of the lower jaw.

4 GUIDES FOR VERTEBRATE DISSECTION

Turn to the lower surface, lift up the posterior margin of the
external ceratohyoid and expose (9) the internal ceratohyoid
muscle, extending outwards and backwards from the hyoid
cartilage to its insertion on the cartilage of the first branchial arch.
Near the insertion of the internal ceratohyoid is (10) the
constrictor arcuum, which extends across the branchial arches
from the first to the third.

Farther out (i.e., more lateral) upon the branchial arches will
be found fibres of (11) a depressor arcuum branchialium, the
origin of which is best seen later, after the removal of the
cucularis and omohyoid muscles.

Muscles of the Shoulder-girdle. — Just behind the mylohyoid
muscle on the latero- ventral side of the throat will be found the
anterior end of the procoracoid cartilage. From the anterior end
of this the (1) procoraco-humeralis muscle extends backwards to
the proximal end of the humerus. It is small and slip-like in
character and serves to draw the limb forward.

The space between the two procoraco-humerales is occupied
by (2) the broad sternohyoid muscle, its fibres in front being
inserted upon the hyoid arch and forming the fascia to which
the geniohyoid (supra) is attached. Posteriorly the sterno-
hyoid is in part attached to the shoulder-girdle, while another
portion continues backwards along the ventral surface of the
body as the abdominal muscles (vide infra).

The pectoralis muscles (3) are fan-shaped. Each arises
from the mid-ventral line, the posterior portion being continuous
with the rectus abdominis muscles to be noticed later. The
fibres converge upon the proximal ventral end of the humerus. The
pectorales serve to draw the shoulders ventrally and backwards.

Cut across one of the pectorales in front, turn it back, and
see (4) the supracoracoid muscle extending from the coracoid
cartilage, between the two shoulders, to the humerus.

On the side of the body dorsal to the attachment of the fore
limb is (5) the latissimus dorsi muscle, a broad sheet whose fibres
converge ventrally upon the dorsal surface of the humerus. In
front of this and between it and the procoracoid are several
muscles as follows:

Just in front of the latissimus dorsi is (6) the dorsalis scapulae,
arising from the dorsal portion of the scapula and inserted,
beside the others, upon the humerus. Next in order is (7) the

NECTURUS 5

cucularis muscle, arising by two heads from the sides of the trunk,
behind the gills, and inserted, like the others, upon the humerus.

Between the cucularis and the procoraco-humeralis is the
(8) omohyoid muscle.

Separate these muscles at their origin and reflect them,
exposing deeper muscles beneath as follows: Beneath the
latissimus dorsi a rudimentary (9) serratus magnus, the fibres of
which, running longitudinally, are attached to the posterior
dorsal angle of the scapula. Beneath the cucularis (10) the
levator scapulae.

Muscles of the Fore Limb. — In the fore limb, besides other
muscles the following may be made out: (1) On the ventral
surface a narrow biceps muscle, extending from the proximal end
of the humerus to the anterior (radial) side of the forearm.
Behind this, also on the ventral surface, is the larger (2) coraco-
brachialis muscle arising from the coracoid cartilage and in-
serted on the distal end of the humerus.

On the dorsal side is (3) the large triceps muscle which arises
by three heads, attached respectively to the coracoid, scapula,
and proximal end of the humerus, and is inserted on the ulna
(posterior side of the forearm) .

In the forearm the muscles may be grouped in two divisions:
on the dorsal surface an extensor communis; on the ventral a
flexor communis. Both flexors and extensors can be resolved
into several components.

Draw dorsal, lateral, and ventral views of the head and body
showing all the muscles. In the dorsal and ventral view put the
superficial muscles on one side of the median line, the deeper
muscles on the other.

Muscles of the Trunk. — In the trunk region the muscles of the
two sides are distinct from each other, and on either side they
are divided into dorsal and ventral portions by a lateral line.
The ventral portions are the more modified. In each portion
the muscles are subdivided by transverse non-muscular parti-
tions— the myosepta or myocommata — into separate myotomes
or myomeres. The dorsal myotomes constitute a longissimus
dorsi muscle on either side, while the ventral region is composed
of three layers of oblique muscles, external, middle, and internal,
the latter best seen from the ccelom. Make out the direction ot
the muscle-fibres in each layer.

6 GUIDES FOR VERTEBRATE DISSECTION

On either side of the mid-ventral line is a narrow rectus
abdominis muscle, each being continuous in front with the
pectoralis muscle, the two rectus muscles being separated by a
non-muscular linea alba.

Draw a diagram of the trunk muscles sho\ving alT these points.

Muscles of the Pelvic Girdle and Hind Limb. — Extending from
the mid-ventral line to each hind limb are three muscles. In
front, arising from the anterior end of the pubis is (1) the pectineus
muscle, which is inserted on the proximal end of the femur.
Behind this, but also arising from the pubis, is (2) the pubo-
femoralis brevis muscle, inserted on the middle of the femur.
The posterior, (3) the gracilis muscle, arises from both pubis and
ischium and is inserted on the distal portion of the femur.

Lift the gracilis and find beneath it the (4) adductor femoris
muscle with somewhat similar origin and insertion.

On the anterior side of the thigh is (5) the rectus internus
muscle, arising from the anterior margin of the acetabulum and
inserted on the proximal end of the tibia.

Behind this, on the ventral surface, is (6) the vastus internus,
also extending from the acetabulum to the tibia. Behind the
vastus internus is the distal end of the gracilis (3), already seen,
while on the posterior margin of the limb is a part of (7) the
femoro-caudalis muscle which arises from the pyriformis (see
below) and is inserted on the fibula.

On the ventral surface of the shank are several muscles which
may be grouped as (8) a flexor communis.

Dissect out the gelatinous tissue around and in front of the
anus and then make out, on either side, two superficial muscles
extending backwards to behind the vent. The more lateral is
(9) the pyriformis, the more medial, (10) the ileo-caudalis.
Trace each to its origin and insertion. Then lift the pyriformis
and find beneath it (i.e., dorsal) the rest of the femoro-caudalis
already seen.

Draw a ventral view of these parts with the muscles found.

In a dorsal view of the limb find the rectus internus, gracilis
and femoro-caudalis seen on the dorsal side. Just behind the
rectus internus is (11) the rectus externus, extending from the
ilium and terminating by a tendon on the tibia. Next behind is
(12) the glutaeus maximus, arising from the ilium and inserted
by tendon on the fibula. The semimembranosus muscle (13)

NECTURUS 7

lies between the glutseus and the gracilis and extends from the
ileo-ischial region to the fibula. The muscles of the dorsal surface
of the shank act as an extensor communis.

Draw a dorsal view of the limb and the adjacent parts of the
trunk, showing the muscles.

VISCERAL ANATOMY

Open the abdominal or peritoneal cavity of the injected
specimen (coelom) by a longitudinal incision a little to the right
of the mid- ventral line, taking care not to injure the under-
lying organs or to cut the pectoral or pelvic arches. Make
lateral cuts on the right side so that the wall may be folded
outwards. See the thin membrane (mesohepar) connecting the
liver with the ventral body wall. How far does it extend in
either direction? Do you find any blood-vessels in it?

Now make similar cuts in the other side, cut the mesohepar,
and pin out the body walls. Tip the liver to the right, slightly
separate the viscera, without cutting or tearing any of the
membranes, and draw the parts exposed, as follows:

The liver, dark-colored and nearly median in position. How
many lobes to it? Lift the lobes and find a small vesicle, the
gall-bladder, on their dorsal surface. Trace the bile-duct from
the gall-bladder to the liver and to the intestine. To the left of
the liver is the stomach. Can you distinguish where stomach
ends and intestine begins? Cut into the intestine behind the
entrance of the bile-duct and carry the incision forward. The
abrupt change noticeable in the character of the lining marks
the boundary (pylorus).

Follow the intestine back to the pelvic region. See the
lobulated pancreas near the entrance of the bile-duct. Examine
the inner surface of the intestine for the opening of its duct.
To the left of the stomach is the elongate, dark-colored spleen.
Look on either side of the liver in the dorsal part of the ccelom
for the elongate lungs. Which lung, right or left, is the larger?

Lift the intestine and see that it is bound to the dorsal body
wall by a thin membrane, the mesentery, and that the stomach
is supported in a similar way by a mesogaster. A membrane, the
gastro-hepatic omentum, extends from stomach to liver, while
liver and intestine are connected by an hepato-duodenal omen-

GUIDES FOR VERTEBRATE DISSECTION

turn. That part of the mesentery which supports the hinder end
of the intestine is the mesorectum.

Now examine the extent of the body cavity. It is lined every-
where by a smooth membrane, the peritoneum, which also covers
mesenteries and viscera so that all organs really lie outside the
peritoneum. In front note that the body cavity is bounded by
a thin membrane, the false diaphragm or septum transversum.

Various blood-vessels course in the mesenteries and omenta.
Make out the following, drawing them in a separate sketch as
you proceed, the arteries in red, the veins in blue.

In the middle line of the dorsal wall of the coelom is the
large artery, the dorsal aorta. From this arise several arteries.
In the mesogaster is the gastric artery, which soon branches and
supplies both sides of the stomach. Which of the branches,
right or left, gives off twigs (splenic artery) to the spleen?

Posterior to the gastric artery are segmental intercostal
arteries leading into the muscles of the back, and, in the female,
more numerous and smaller arteries supplying the oviducts.

At about the middle of the ccelom the dorsal aorta gives off,
into the mesentery, a cceliac axis which soon divides into a
gastro-splenic artery, going to the stomach and spleen, and a
hepato-pancreatic artery, which supplies not only the pancreas
and liver but sends branches to the stomach as well.

The intestine is supplied by several (how many?) mesenteric
arteries each of which branches in the mesentery into fine twigs
(intestinal arteries) which enter the intestinal walls.

The mesenteric vein runs in the mesentery parallel to the
intestine. It is formed by the union of numerous intestinal veins
from the intestinal wall, and is to be traced forward, through the
pancreas, receiving a pancreatic vein in its course, to its union
with the gastro-splenic vein to form the hepatic portal vein which
enters the liver near the bile-duct. The gastro-splenic vein is
formed by the union of gastric and splenic veins coming from
stomach and spleen respectively. The hepatic portal vein runs
for some distance along the dorsal surface of the liver and is rein-
forced in its course by a ventral abdominal vein which passes
dorsally from the ventral body wall. Trace the branches of the
portal vein on and in the liver.

A second vein, the postcava (vena cava inferior) extends
from about the middl0 of the dorsal surface of the liver dorsally

NECTURUS 9

and posteriorly to about the middle of the body cavity. Cut
into it near the liver, and with probe and scalpel trace the postcava
through the liver to the false diaphragm, noting the entrance of
small vessels, the hepatic veins, during its course. At about the
point where the postcava leaves its dorsal position to enter the
liver it connects with the hinder ends of a pair of postcardinal
('azygos') veins into which pass small veins from the anterior
genital organs and the spinal region.

Add these vessels to your sketch.

Cut through the stomach at about the middle and through
the intestine in the pelvic region. Cut the alimentary canal
loose by trimming the mesogaster, mesentery, etc., close to the
intestine. Also remove most of the liver, leaving the anterior
portion, together with part of the postcava, attached to the
septum transversum. You can now study

The Urogenital Organs. — In the male these consist of the testes
and their efferent ducts together with the mesonephroi (the so-
called kidneys); in the females, besides the mesonephroi, of the
ovary and its ducts. Two specimens will be needed to make out
all the features.

In the male the testes are a pair of solid oval bodies l}dng in
the posterior part of the roof of the body cavity. Each is sup-
ported by a fold of the peritoneum, the mesorchium, in which
blood-vessels, spermatic arteries and spermatic veins, may be
traced, the former coming from the dorsal aorta to the testes,
the latter passing from the testes to enter the postcava. Add
these vessels to the sketch of the circulation already made.

Next find the ducts leading from each testis, the vasa efferentia,
these uniting to form a common convoluted tube, the vas deferens
or Leydig's duct. Trace this latter in both directions. How far
forward does it extend? This portion in front of the testis is
functionless. Sketch the reproductive organs on one side of
the body as far as made out. Then cut away the testis of the
opposite side. This will expose the mesonephros (Wolffian body)
lying between the vas deferens and the median line. Sketch this
and the related structures on the other side of the drawing.
Note that the mesonephros is narrower in front than behind.
See that the vasa efferentia pass through this narrower portion
in order to reach Leydig's duct. Farther back see the urinary
tubules leading from the mesonephros to Leydig's duct, which

10 GUIDES FOR VERTEBRATE DISSECTION

therefore must serve for ureter as well as for vas deferens; in
other words it is urogenital in function.

Cut through the pelvis and trace the posterior end of the
alimentary canal and urogenital ducts. That part into which
the ducts empty is the cloaca. On its ventral side is a thin-
walled urinary bladder. Inflate through the vent and notice its
shape. Beginning at the vent split the cloaca a little to one
side of the mid-ventral line; lay open and find the opening of
the urinary bladder, and in the sides the openings of Leydig's
ducts.

In the female the much lobulated ovary occupies a position
comparable to that of the testis in the male. It is attached to
the peritoneal wall by a membrane, the mesovarium. Notice
through the ovarian walls the eggs of various sizes. Make a
slight incision in the wall of the ovary and inflate, noting that
the organ is saccular. What relations do the ova bear to its wall?
Also note the ovarian arteries going from the dorsal aorta to the
ovary.

Dorsal to the ovary is a long convoluted tube, the oviduct
(Mullerian duct); trace it forward and back. Cut into it near
its anterior end. Note that it opens directly into the body
cavity in front (ostium tubae). Trace it also into the cloaca,
inflating and cutting if necessary. In the posterior part of the
coelom between the oviduct and the middle line is the meso-
nephros. Do you find vasa efferentia similar to those in the
male? Notice on the lateral margin of the mesonephros a
delicate tube, the ureter (Wolffian duct). Trace it backwards:
does it unite with the oviduct or does it open separately into the
cloaca?

What is the most marked difference between the urogenital
ducts in the two sexes?

Draw the urogenital system of both sexes, bringing out the
points discovered.

Posterior Circulation. — Follow the postcava backward from
the point of its connection with the postcardinals, sketching this
part us well as the renal and genital veins which it receives.

Cut through the pelvis and BOO, "ii cither side of the hinder
part of the coelom, an iliac artery which soon divides, one branch
(femoral artery) passing into the hind limb, the other passing to the
ventral side of the body, where it forms a hypogastric artery,

NECTURUS 11

giving off a twig to the urinary bladder in its course. Trace the
femoral artery along the posterior side of the thigh to its division
at the knee and trace both branches into the foot.

The femoral vein also occurs on the posterior side of the leg
Trace it proximally to its junction with a renal portal vel*
which extends along the outer side of the mesonephros, reaching
forward to the genital region. Behind, the renal portal \eins of
the two sides unite and receive a caudal vein from the tail as well
as smaller pelvic veins. From each femoral vein there also arises
a pelvic vein, the two uniting to form a ventral abdominal vein
which runs forward in the ventral body wall and eventually passes
into the liver through the mesohepar, to unite with the hepatic
vein. Trace the renal portal vein of either side forward to the
anterior limits of the coslom. The portion of the vessel in front
of the mesonephros is called posterior cardinal vein.

Add these parts to your sketch.

Now trace the connection of the femoral artery with the
aorta and trace the aorta, now called the caudal artery, into the
tail, noting the cloacal branches. Do you find spinal or inter-
costal arteries (p. 8) in this region?

Add these to the sketch together with the pulmonary artery
and vein, the latter on the ventral, the former on the dorsal, side
of the lung. Trace both as far forward as the septum.

The Heart. — Cut through the ventral wall of the body just
in front of the fore legs, laying open the pericardial cavity in
which the heart lies. Note that the cavity is lined with a smooth
membrane, the pericardium, comparable to the peritoneum. In
the heart make out the following parts: Behind and attached
to the septum transversum, the sinus venosus. Anterior to
this on the ventral side, the thick, muscular ventricle, from
which a tube, the truncus arteriosus, leads to the anterior wall
of the pericardial cavity. Dorsal to the ventricle are a pair of
auricles.

Inflate by blowing into the part of the postcava left attached
to the liver. Does this demonstrate a connection of postcava
and sinus venosus?

Lay open the ventricle from the ventral surface and, if neces-
sary, remove the blood or injecting mass from the interior. Fol-
low forward with the incision, splitting the ventral wall of the
trunctis arteriosus. Do you find any valves between ventricle

12 GUIDES FOR VERTEBRATE DISSECTION

and truncus? Farther forward the walls of the truncus are
thickened and muscular, forming a bulbus arteriosus. How
many openings do you find from the auricles into the ventricle?
Cut into the auricles: are the chambers entirely distinct from
each other? Do both connect with the sinus venosus? If not,
which one, right or left, has such a connection?

Make a diagrammatic sketch of the heart, showing the relations
of the chambers.

The Afferent Branchials. — Follow the truncus arteriosus
forward in front of the pericardium by removing the covering
muscles and notice that it branches almost immediately into
right and left trunks, the portion before the branching being all
that remains of the ventral aorta. Trace out one of the branches
and see how it divides into afferent branchial arteries. How
many are there of these? and what relation does each bear
to branchial arches, gill-slits, and external gills? Cut off one of
the gills and see the vessels in it. How would you describe their
position?

Add the heart and the afferent branchial arteries to the sketch.

The Mouth. — Insert strong scissors at the angle of the mouth,
the points of the blades extending just dorsal to the external
gills; cut, and lay back the floor. Make a sketch of the roof of
the mouth showing the distribution of teeth in three pairs of
patches upon the premaxillaries, vomers, and the anterior end
of the palatopterygoids. Find the internal nares (choanae) by
probing from the external nostrils.

In the floor of the mouth see the short tongue. Recognize in
it, by feeling, the hyoid cartilage and extending outwards and
backwards from this the branchial cartilages. What relation
do these bear to the gill-slits? Insert gill-clefts and teeth in a
sketch of the floor of the mouth, and, by dotted lines, the posi-
tions of the cartilages. Note the projections on the margins of
the gill-clffts; to what in fishes are they to be compared? Do
you find internal gills? In the median line behind is a narrow
slit, the glottis. Insert a blowpipe in it and inflate. What
happens to the lungs? Notice the change in the lining of the
throat just behind the glottis, indicating the line between pharynx
and oesophagus.

Indicate these features in the sketch of the floor of the mouth.

Slit up the oesophagus, lay open the roof of the mouth cavity

NECTURUS 13

and trace the aorta and postcardinal veins forward, stripping off
the skin to see the parts more clearly. At the level of the
shoulder-girdle the aorta gives off a subclavian artery on either
side, in front of which it divides into two vessels, the radices
aortse. Lateral to the radices are the anterior ends of the post-
cardinal veins. Trace them as they bend to enter the sinus
venosus. This portion is called the ductus Cuvierii.

Follow one radix aortaB forward into the gill region, noting the
vertebral artery which it gives off on its medial side. In front
of the origin of the vertebral the radix bends laterally to pass,
as the second efferent branchial artery, along the dorsal side of
the middle gill, receiving in its course a third efferent artery from
the last gill. At the point of bending the radix is connected by
a smaller vessel with a similar first efferent branchial artery
which comes from the first gill. From this first efferent artery an
external carotid artery is given off which passes downward and
forward, while the common trunk of radix and first efferent
continues toward the middle line as the internal carotid artery.

Also note, proceeding backwards from the third efferent
branchial , the pulmonary artery, which should be traced to the
lung of the same side.

Add these vessels to your drawing.

The venous trunks of the head are more difficult to follow.
Follow the anterior cardinal or jugular vein forward from the
ductus Cuvierii, noting its branches: first a subclavian vein,
next a division into internal jugular, coming from the brain, and
external jugular vein, from the face and lower jaw. See also
a lateral vein entering the Cuvierian duct of either side and trace
it back into the side walls of the body.

Add these vessels to the sketch and then follow out and add
the remainder of the pulmonary artery and the subclavian artery
and vein. Note, arising from the subclavian artery and passing
back near the mid-ventral line of the ccelom, a cutaneous artery.

(The head may now be cut from the trunk and placed for a
day or two in nitric alcohol to decalcify it for the study of the
brain. While this is being done the skeleton (p. 15) may be
studied.)

The Brain. — Take the head from the nitric alcohol, rinse for
15 minutes in running water, and then very carefully remove
muscles and decalcified bone from the roof until the whole top

14 GUIDES FOR VERTEBRATE DISSECTION

of the brain is exposed. In this make out the following
parts:

In front a pair of elongate cerebral hemispheres, telencephalon
or prcsencephalon, each prolonged in front as a narrower olfactory
nerve.* Between and behind the hemispheres is the choroid
plexus, which is followed by the 'twixt-brain (di- or thalamen-
cephalon) and midbrain (mesencephalon), which are separated
externally by a slight furrow. On the roof of the diencephalon
is a flattened vesicle, the pinealis. The cerebellum (meten-
cephalon), a slight transverse fold, lies behind the mesencephalon,
and bounds anteriorly the fossa rhomboidalis, a triangular opening
into the large posterior region of the brain, the medulla oblongata
(myelencephalon) . (If very carefully opened it is possible to
preserve the roof of the third ventricle in the diencephalon and
the large choroid plexus covering the fossa rhomboidalis.)

Draw the brain from above X6, and then insert the nerves
arising from it, as follows:

I. The olfactory nerve, arising from the anterior end (olfactory
lobe) of the telencephalon. II. The optic nerve, passing out from
the floor of the diencephalon and appearing at the sides, beneath
the hinder angles of the cerebrum. III. The oculomotor nerve,
appearing in the angle between mes- and myelencephalon. IV-
The trochlearis nerve, not readily found except by use of the
microscope. It arises from the roof between mes- and meten-
cephalon. V. The trigeminal nerve, arising as a strong trunk
from the anterolateral portion of the myelencephalon and passing
obliquely outwards and forwards. Follow it "hrough the cranial
wall to its enlargement, the Gasserian ganglion. From this
ganglion three branches are easily followed (a) an ophthalmicus
profundus, passing straight forward; (6) a maxillaris superior,
following more closely the margin of the upper jaw; and (c) the
mandibularis, going to the lower jaw. VII-VIII. The facialis
and auditory nerves arise just behind the trigeminal by several
superimposed roots. The dorsal root goes straight to meet the
Gasserian ganglion, while the othv3r roots fuse and send laterally a
strong facialis proper and, behind, branches to the inner ear. (The
sixth nerve is closely associated with the facial so that it is

* The division of what arc apparently cerebral hemispheres into hemi-
spheres proper and olfactory lobes is not very evident, being marked by a
very slight constriction.

NECTURUS 15

not readily distinguished from above.) IX-X. Four roots one
after the other form the next nerve. The most anterior of these
is the glossopharyngeal nerve, the rest compose the vagus nerve.
All unite to form the vagus ganglion, from which several nerves
can be traced.

Remove the brain from the skull and draw its ventral surface.
Note the origin of the optic nerves (they really cross) and the
large hypophysis, a structure in the median line between the floor
of the 'twixt-brain (infundibulum) and the medulla oblongata.
The roots of the sixth nerve (abducens) may be found near the
middle line of the lower surface of the medulla nearly between
the roots of the glossopharyngeal.

SKELETON

The skeleton consists of axial and appendicular portions.
The axial skeleton includes the vertebral column, ribs, and skull;
the appendicular consists of the framework of the limbs and the
arches or girdles by which they are connected to the trunk. The
vertebral column may be divided into four regions: cervical
(neck), dorsal (trunk), sacral (articulation of girdle of hind limbs),
and caudal (tail).

Study a vertebra from about the middle of the dorsal region,
making out the following features. On the ventral side in the
middle line a body or centrum shaped like an hour-glass. Is it
concave in front (procoelous), behind (opisthoccelous) , or at both
ends (amphicoelous) ? Dorsal to the centrum is the neural arch
enclosing a spinal canal for the spinal cord. This arch consists
of two plates (neurapophyses) which meet above and bears on its
dorsal surface a projection, the neural spine.

In front each neurapophysis bears a projection, the prezyga-
pophysis, which articulates with a similar postzygapophysis
developed from the vertebra in front. How do these zygapophyses
overlap?

Extending laterally from each vertebra is a transverse process,
directed outwards and backwards and composed of two parts,
a diapophysis, arising from the neural arch, and a parapophysis,
from the centrum. Dia- and parapophyses are connected by a
thin plate, the vertical lamina, and the parapophysis is expanded
at its base by a similar horizontal lamina which unites with the

16 GUIDES FOR VERTEBRATE DISSECTION

centrum for nearly its whole length. (In carefully prepared
specimens dia- and pleurapophyses contain cartilages with which
the ribs articulate, but usually these are lost.) The horizontal
lamina is perforated by the foramen ventrale (for the collateral
vertebral vessels), which passes, posterior to the pleurapophysis,
to a deep pit, the posterior vertebral fossa, bounded by centrum,
transverse process, and postzygapophysis.

• The ribs are short, tapering somewhat distally, while proxi-
mally each is forked, presenting two surfaces, a dorsal tubercular
and a ventral capitular head, for articulation with dia- and para-
pophyses.

Draw a vertebra and ribs from different sides showing these
points.

Compare other vertebrae with this one. Where is the neural
spine largest? Do all bear transverse processes? Is the ventral
foramen present in all?

The first vertebra is the atlas. What is the relative length
of its centrum? Is it amphiccelous? On its anterior surface are
a pair of slightly concave surfaces (condylar facets) for articula-
tion with the base of the skull. Does the atlas bear ribs?

The vertebra with which the hind legs are connected (by
means of the pelvic girdle) is the sacrum. Could the element
intervening between this vertebra and the pelvic arch be con-
sidered as a rib? Has it two heads? Counting the atlas as 1,
what is the number of the sacrum in your specimen? Compare
with other skeletons in the laboratory; is the numerical position
of the sacrum constant?

Study the caudal vertebrae. On what one does an arch
(haemal arch) on the ventral side, comparable to the neural arch,
appear? Is there a disappearance of parts towards the tip of
the tail? Are transverse processes constant throughout the
series? Are ribs present on any of the caudal vertebras? How
many caudal vertebrae are present?

(Sternum.— Wilder has described cartilages in the ventral
body wall, unconnected with other parts, which are regarded as
sternebras, or sternal elements. They are lost in skeletons pre-
pared in the ordinary way.)

The Skull is composed of two parts, the cranium, containing
the brain and special sense-organs, and the visceral skeleton,
connected with the alimentary tract. In the cranium, in turn,

NECTURUS 17

distinct parts, cartilaginous and osseous, are to be recognized.
In the dry skull the cartilaginous parts are not readily made out,
but by soaking in water they usually become visible.*

The cranium is at first developed in cartilage forming a chondrocranium,
which, while incomplete in parts, can be compared to that of the elas-
mobranch. As development proceeds this cartilage is in part con-
verted into bone (cartilage bone) and in part covered by other bones
(membrane bones) which never pass through a cartilage stage but are
developed from the deeper layer of the skin. The distinctions between
these two kinds of bone cannot be recognized in the adult, but only by
tracing the history. A list of each group occurring in the cranium of
Necturus is given here.

Cartilage Bones: 2 exoccipitals, 2 epiotics, 2 prootics, 2 pterygoids,
2 stapes, and 2 columellas.

Membrane Bones: 2 parietals, 2 frontals, 2 premaxillaries, 2 vomers,
2 squamosals, and 1 parasphenoid.

Quadrates, pterygoids, and premaxillaries rightly belong to the
visceral skeleton, but they are so intimately united to the cranium that
they may be considered with it.

In studying the skull, after recognizing the position of any
element, carefully trace its boundaries with the hand-lens, noting
the exact position of the joints (sutures) between it and the
adjacent bones.

The cranium presents a base, where it connects with the trunk,
and dorsal and ventral surfaces. In the base is a large opening,
the foramen magnum, through which the brain connects with the
spinal cord. On either side of this foramen is an exoccipital
bone, which bears on its posterior surface an occipital condyle
for articulation with the atlas.

On the side the exoccipital articulates with an opisthotic
bone which extends to both dorsal and ventral surfaces, while
laterally it forms the postero-lateral angle of the skull.

Draw the cranium from behind, X4.

The dorsal surface of the skull is covered behind by a pair
of large parietal bones which meet in the middle line, while in
front they articulate with a pair of frontal bones which extend
forward nearly to the tip of the snout. The tip of the cranium

* It is well to keep the skulls in 95% alcohol in which a little Lyons blue
is dissolved. When required for study they may be placed in water which
swells the cartilages while the blue has stained these parts so that they are
distinctly seen. At the close of the exercise return them to the alcohol.

18 GUIDES FOR VERTEBRATE DISSECTION

is formed by a pair of premaxillary bones which meet at an
angle, each sending backwards an ascending process which
partly covers the anterior end of the frontal of the same side.
The rest of the premaxillary is formed by a tooth-bearing alveolar
process.

Wedged into the angle between the antero-lateral part of the
frontal and the alveolar process of the premaxillary is the upper
surface of the vomer, the posterior portion of which is covered
by the cartilaginous antorbital process of the chondrocranium
to be studied later.

Extending obliquely outwards and forwards from the external
surface of the opisthotic is a slender splint-like squamosal bone
which articulates in front with the quadrate, while at about the
middle of its lower margin it gives off a short opercular process
which articulates with the stapes (infra). The quadrate, just
referred to, is a splint-like bone just inside the squamosal and
expanded at its anterior end where it bears a shallow fossa with
which the lower jaw is articulated. The posterior portion lies
close to the quadrate cartilage from which it has arisen by ossi-
fication.

At its posterior end the quadrate meets the lateral surface of
the prootic bone, parts of which are visible in both dorsal and
ventral views of the skull, the more medial portions being covered
by the parietals above and the parasphenoid below.

Extending inwards and forwards from the quadrate to the
vomer is the palatopterygoid bone, the limits of which are best
seen in the vqntral view of the cranium.

Draw a dorsal view of the skull X4.

On the ventral surface of the cranium in the middle line is a
large parasphenoid bone, the anterior end of which lies between
the palatine processes of the two vomers. The vomers (already
seen from above) present, besides this palatine process, a tooth-
bearing alveolar process which articulates behind with the
anterior end of the palatopterygoid, this latter having teeth in
front continuous with those of the vomer. The palatopterygoid
articulates behind with the quadrate bone and the quadrate
cartilage.

In drawing the ventral view of the cranium, insert these
parts as well as the quadrate, prootic, opisthotic, and exoccipital
bones recognized in the dorsal view.

NECTURUS 19

The chondrocranium (cartilaginous skull) can be studied by
taking the head of a fresh or alcoholic (not formalin) specimen,
removing the skin and dissolving the flesh, etc., by warm soap
solution, taking care that it does not get hot enough to injure
the cartilage. Then, with the scalpel the membrane bones,
enumerated above, may be readily removed, leaving but the
chondrocranium and the bones ossified in it. The nasal capsules
are usually so injured that they are not mentioned here.

The chondrocranium consists behind of a pair of irregularly
oval hollow bodies, the otic capsules connected above with each
other by a narrow cartilage band, the synotic tectum, below by a
broader cartilage, the remains of a primitively much larger para-
chordal plate. On the medial side each otic capsule has a large
foramen for the passage of nerves and blood-vessels, while on the
inferolateral surface an opening, the fenestra ovalis, is occupied
by the stapes. The walls of the capsule are made up largely of
pro- and opisthotic bones, the extent of which can now be clearly
seen.

From the anterior end of each otic capsule a slender cartilage
bar, the trabecula, extends to near the snout, where the trabeculae
of the two sides are connected by a median ethmoid plate, be-
yond which the trabeculae continue as the cornua trabecularium.
From each trabecula, near its anterior end, an antorbital process *
is directed outwards and slightly forwards, in front of the eye.

The quadrate bone and cartilage are best considered together.
They extend outwards and forwards from the otic capsule to
the articular surface for the attachment of the jaw and to the
hinder end of the pterygoquadrate. From this as a centre they
give off two diverging processes, an otic, extending to the prootic
bone, and an epipterygoid process, reaching to the base of the
trabecula.

This cartilaginous skull will also show well the stapes, a
rounded plate of bone, with a prominent columellar process,
fitting in the fenestra ovalis.

The lower jaw consists of two halves loosely united in front,
and each half consisting of three bones arranged around a car-
tilage bar. These bones are a tooth-bearing dentary in front and
on the outer side; a plate-like, tooth-bearing splenial at about

* Sometimes regarded as the anterior part of the pterygoquadrate archf
but not proved to be such.

20 GUIDES FOR VERTEBRATE DISSECTION

the middle of the inner surface and a large angular bone making
up most of the inner surface. Between these bones runs Meckel's
cartilage, its posterior end enlarged for articulation with the
quadrate. (In many vertebrates this end ossifies as an articular
bone.)

Draw the lower jaw from the inner and outer surfaces.

The rest of the visceral skeleton is composed of a series of
cartilage arches in the floor of the mouth and throat. These
arches, of which there are four, are connected together by a
longitudinal median portion, the copula. The most anterior
arch is the hyoid, each half of which is composed of a small medial
hypohyal and a larger and more lateral ceratohyal. The copula
between the hyoid and the next (the first branchial) arch is the
first basibranchial. Each half of the first branchial arch is
composed of a ceratobranchial next the middle line, and a larger
distal epibranchial. Branchial arches 2 and 3 are more incom-
plete, the ceratobranchial elements being small or absent. Be-
hind the first ceratobranchials the copula is continued by a
slender bone, the second basibranchial.

Draw this hyoid-branchial apparatus.

The pectoral, or shoulder girdle, is that arch of cartilage and
bone which supports the fore limbs. Its two halves are not
connected, but overlap ventrally. Each half consists of dorsal and
ventral portions. In the ventral portion, which is entirely car-
tilaginous, distinct elements cannot be recognized but merely
regions, a procoracoid in front, a coracoid behind, the limits
between the two being slightly indicated by a small opening, the
coracoid foramen, passing through the cartilage and by the pit,
the glenoid fossa, by which the arm is articulated to the girdle.
The dorsal half of the girdle consists of a bony element, the
scapula, continued dorsally by a larger cartilaginous plate, the
suprascapula.

The bone of the upper arm (humerus) is cartilaginous at
either end, but has a bony shaft. On the lower surface it presents
a strong crista deltoidea for the attachment of the thoracic
muscles. In the forearm are two bones, the radius on the thumb
or anterior side, the ulna on the other; both have cartilaginous
ends, the proximal of the ulna extending beyond the elbow-
joint as a strong olecranon process.

In the wrist (carpus) then- are six or seven cartilages arranged

NECTURUS 21

as follows: a proximal row of two, a radiale on the radial side, and
an ulnare on the other, to which is usually fused a middle element,
the intermedium. The distal row consists of three carpales,
while a centrale lies between the two rows.

The carpus is followed by the palm, metacarpus, and this
in turn by the digits. How many metacarpal bones, and how
many bones (phalanges) in each finger? (The thumb — pollex —
or first digit is absent.)

The pelvic girdle is largely cartilaginous, its two halves
being fused in the mid-ventral line. On either side the pelvis
bears a bony element, the ilium, which articulates by the inter-
vention of a cartilage with the sacrum. At the base of the
ilium is a pit, the acetabulum, for the articulation of the
hind limb. The ventral half of the girdle forms a flat plate, the
anterior part of which is the pubis, the posterior the ischium.
In the ischial region is an ossification, and the limits between
ischium and pubis are indicated by a small obturator foramen

The bones of the hind limb correspond very closely with those
of the arm — femur to humerus, tibia and fibula to ulna and
radius, tarsus to carpus (tibiale, fibulare, centrale, tarsales),
metatarsals to metacarpals — except that there are two ridges
(cresta ventralis, c. lateralis) on the femur. As in the hand the
first digit (hallux) is lacking.

Draw both girdles and the skeleton of each limb, indicating
in your drawing bone and cartilage.

/

22 GUIDES FOR VERTEBRATE DISSECTION

LITERATURE

THE following list of papers upon the morphology of the Urodeles
contains the more important works relating to the group, as well as some
of the lesser notes relating to Necturus. It includes, besides articles on
the anatomy, others upon the organogeny which are necessary to the
understanding of the structures dissected.

GENERAL WORKS

Handbuch der vergleich. und experiment. Entwicklungsgeschichte der Wirbel-
thiere. Jena, 1901-6.

BUMPUS, H. C. A contribution to the study of variation. (Skeletal varia-
tions in Necturus.) Jour. Morphol., 12, 1896.

COPE, E. D. Structure and affinities of Amphiuma. Proc. Amer. Phil.
Socy., 1886.

- Ratrachia of North America. Bulletin 34, U. S. Nat. Mus., Wash-
ington, 1889.

EMERSON, E. T. Anatomy of Typhlomolge. Proc. Bost. Soc. Nat.

Hist,, 32, 1905.
EYCLESHYMER, A. C. Formation of embryo of Necturus. Anat. Anz., 21,

1902.

- Habits of Necturus. Am. Nat., 40, 1906.

FISCHER, J. G. Anatomische Abhandlungen uber die Perennibranchiaten

und Derotremen. Hamburg, 1864.

GADOW, II. Amphibia in Cambridge Natural History. London, 1905.
GEGENBAUR, C. Vergleichende Anatomic der Wirbcltiere. 2 vols. Leipzig,

1898-1901.
GREEN, I. M. Peritoneal epithelium of some Amphibia. Trans. Amer.

Micros. Socy., 18, 1897.

HERTWIG, R. Manual of Zoology. Translated by J. S. Kingsley, N. Y.
VAN DER HOEVEN, J. A natomie van Cryptobranchus. Haarlem, 1862.

Bijdragen tot de Kcnnis van Menobranchus. Leiden, 1868.

HOFFMANN, C. K. Amphibia, in Bronn's Klassen und Ordnungen des

Thicrrciches. Leipzig, 1873-78.
HOUGHTON, H. S. Muscular and skeletal elements in Spelerpcs. Ohi o

Naturalist, 3, 1903.

HUXLEY, T. H. Anatomy of Vertcbrated Animals. N. Y., 1872.
Structure of skull and heart of Menobranchus. Proc. Zool. Socy.

London, 1874.
HYRTL, J. Cryptobranchus japonicus. Vindobonae, 1865.

NECTURUS 23

KINGSBURY, B. F. Columella auris and Nervus facialis in the Urodela.

Jour. Comp. Neurol., 13, 1903.

Rank of Necturus. Biolog. Bulletin, 8, 1905.

KINGSLEY, J. S. Head of an embryo Amphiuma. Amer. Nat., 26, 1892.

Text-book of vertebrate zoology. N. Y., 1899.

Systematic position of the Ccecilians. Tufts College Studies,

No. 7, 1902. (Comparisons with Urodeles.)
MINOT, C. S. Vertebrate embryology. N. Y., 1892.
OSBORN, H. L. Anatomy of Axolotls. Amer. Nat., 35, 1901.
OWEN, R. Anatomy of Vertebrates. 3 vols. London, 1866-68.
PARKER, G. H. Variations in the vertebral column of Necturus. Anat.

Anzeiger, 11, 1896.
PLATT, J. B. Development of cartilaginous skull and of branchial and

hypoglossal musculature in Necturus. Morph. Jahrbuch, 25, 197.
Ontogenetische Differenzirung des Ektoderms bei Necturus. Archiv

mikr. Anat. 43, 1894.

PRATT, H. S. Vertebrate anatomy. Boston, 1905.
REESE, A. M. Anatomy of Cryptobranchus. Amer. Nat., 40, 1906.
Enteron and integument of Cryptobranchus. Trans. Am. Micros.

Socy., 26, 1905.
STANNIUS, H. Lehrbuch der Zootomie. Berlin, 1852. (Valuable; a

summary of all previous work.)

WAITE, F. C. Specific name of Necturus. Amer. Nat., 40, 1906.
WIEDERSHEIM, R. Salamandra perspicillata und Geotriton fuscus.

Genua, 1875.

Vergleichende Anatomie der Wirbeltiere. Jena, 1906.

Anatomie des Amblystoma. Zeitschr. wiss. Zool., 23, 1873.

WILDER, H. H. Nasengegend von Menopoma und Amphiuma. Zool.

Jahrbuch., Anat. Abth., 5, 1892.

Anatomy of Siren lacertina. Zool. Jahrbuch, iv, 1891.

Early development of Desmognathus. Amer. Nat., 38, 1904.

ZIEGLER, H. E. Lehrbuch der vergl. Entwickelungsgeschichte der niederen

Wirbelthiere. Jena, 1902.

INTEGUMENT, ETC.

ESTERLY, C. O. Structure and regen ration of the poison-glands of

Plethodon. Univ. California Publications, Zoology, 1, no. 7, 1904.
EYCLESHYMER, A. C. Development of Chromatophores in Necturus. Amer.

Journ. Anat., 5, 1906.
LEYDIG, F. Die Hautdecke und Hautsinnesorganne der Urodelen.

Morph. Jahrbuch, 2, 1876.

NICOLGU, P. Hautdriisen der Amphibien. Zeitach. wiss. Zool., 66, 1839.
WIEDERSHEIM, R. Kopfdriisen der geschwdnzten Amphibien. Zeitschr.

wiss. Zool., 28, 1878.

24 GUIDES FOR VERTEBRATE DISSECTION

SKELETON

BAUR, G. Morphologic des Carpus und Tarsus. I. Batrachia. Jena,
1888.

BUCKS, G. Ursprung des Kopfskelettes bei Necturus. Morph. Jahrbuch,
29, 1902.

GADOW, H. Evolution of the vertebral column of Amphibia and Amniota.
Philos. Transact., 187 B, 1896.

GEGENBAUR, C. Vergleichende Anatomic der Wirbelsauk der Amphibien
und Reptilien. Leipzig, 1862.

GOPPERT, E. Morphologic der Amphibienrippen. Festschr. Gegenbaur,
1896.

HAY, 0. P. Skeletal anatomy of Amphiuma during its earlier stages.
Jour. Morphology, 4, 1890.

MURRAY, J. A. Vertebral column of certain primitive Urodela. Anatom.
Anzeiger, 13, 1897.

PARKER, W. K. Structure and development of skull in Urodelous Am-
phibia. Pt. 1. Philos. Trans., 1877.

Morphology of the skull in the Amphibia Urodela. Trans. Linn.

Socy., Series 2, Zool., 2, 1879.

Structure and development of the skull in the Urodeles. Trans. Zool.

Socy. London, 11, 1882.

and BETTANY, G. Morphology of the skull. London, 1877.

PERRIER, A. Laceinture scapulaire ancestrale des Urodeles. Misc. Biolog.
A. Giard, 1899.

REYNOLDS, S. H. The vertebrate skeleton. London, 1897.

SMITH, F. Additional data on the position of the sacrum in Necturus. Am.
Naturalist, 34, 1900.

STOHR, P. Entwick. des Urodelenschddels. Zeitsch. wiss. Zool., 33, 1879.

TERRY, R. J. Two skulls of larval Necturus. Am. Jour. Anat., 3, 1904.

VAN PEE, P. Entincklvng der Extremitdten bei Amphiuma und Nec-
turus. Anat. Anz., 23, Erganzungshefte, 1903, and 24, 1904.

WHIPPLE, I. L. The ypsiloid apparatus of Urodeles. Biolog. Bulletin,
10, 1906.

WIEDERSHEIM, R. Kopfskclett der Urodelen. Morph. Jahrbuch, 2,
1877.

Skelett von Pleurodeles. Jena. Zeitschr., 14, 1880.

Die altestcn Formen des Carpus und Tarsus der heutigen Amphibien.

Morph. Jahrbuch, 2, 1876.

Das Gliedmasseriskelett der Wirbelticre. Jena, 1892.

WILDER, H. II. Skeletal system of Necturus. Memoirs Boston Soc
Nat. Hist., 5, 1903.

WINSLOW, G. M. The chondrocranium in the Ichthyopsida. Tufts Col-
lege Studies, no. 5, 1898.

NECTURUS 25

MUSCULAR SYSTEM

DRUNER, L. Anatomic der Zungenbein-, Kiemenbogen- und Kehlkopf-

muskeln der Urodelen. Zool. Jahrb., Abth. Anat., 15, 1901; 19, 1904.

(See also Anat. Anzeiger, 23, 1903.)
EDGEWORTH, F. H. Development of the head-muscles in the Newt. Jour.

Anat. and Physiol., 36, 1902.
FURBRINGER, M. Vergleich. Anat. der Schultermuskeln. Jena. Zeitsch.

7, 1873.
MAURER, F. Aufbau und Entwicklung der ventralen Rumpfmuskulatur

der Urodelen, u.s.w. Morph. Jahrbuch, 18, 1892.
MIVART, ST. G. Myology of Menopoma, Menobranchus, Chameleo.

Proc. Zool. Socy. London, 1869-70.

NERVOUS SYSTEM

ANDERSON, A. Sympathet. Nervensystem der Urodelen. Zool. Jahr-
buch, 5, 1892.

BOWERS, M. A. Cranial nerves of Spelerpes. Proc. Amer. Acad. Arts
and Sci., 36, 1901.

BURCKHARDT, R. Him und Geruchsorgan von Triton und Ichthyophis.
Zeitsch. wiss. Zool., 52, 1891.

COGHILL, G. E. Cranial nerves of Amblystoma. Jour. Compar. Neurol.,
12, 1902.

ECYLESHYMER, C. A. Paraphysis and epiphysis in Amblystoma. Anat.
Anzeiger, 7, 1892.

FISH, P. A. Central nervous system of Desmognathus. Jour. Morphol., 5,
1895.

GAGE, S. P. Brain of Diemydylus. Wilder Quarter Century Book, 1893.

HERRICK, C. J. Cranial nerves of Amblystoma. Jour. Comp. Neurol.,
4, 1894.

JOHNSTON, J. B. Nervous System of Vertebrates. Philadelphia, 1906.

KINGSBURY, B. F. Brain of Necturus. Jour. Compar. Neurol., 5, 1895.

KINGSLEY, J. S. Cranial Nerves of Amphiuma. Tufts College Studies,
no. 7, 1902.

and THYNG, F. W. The hypophysis in Amblystoma. Tufts Col-
lege Studies, no. 8, 1904.

MCGREGOR, J. H. Cranial nerves of Cryptobranchus. Jour. Comp.
Neurol., 6, 1896.

NORRIS, H. W. Dorsotrachealis branch of seventh cranial nerve in
Amphiuma. Anat. Anzeiger, 27, 1905.

OSBORN, H. F. Brain of Menopoma. Proc. Acad. Nat. Sci. Philadel-
phia, 1884.

SQUIRE, C. A. Brain of Necturus. Bull. Univ. Wisconsin, No. 33, 1900,

26 GUIDES FOR VERTEBRATE DISSECTION

WAITE, F. C. Variations in brachial and lumbosacral plexus of Necturus.

Bull. Mus. Comp. Zool., 31, 1897.
WARREN, J. Development of paraphysis and pineal region in Necturus.

Am. Jour. Anat., 5, 1905.

SENSE-ORGANS

BORN, G. Nasenhohlen und Tranennasengang der Amphibien. Morph.

Jahrb., 2, 1876.
EIGENMANN, C. H. Eyes of Typhlomolge. Trans. Amer. Micros. Socy.,

1899.
GAUPP, E. Schalllcitend Apparatcs bei den Wirbelthiere. Ergebnisse d.

Anat. u. Entwicklungsgeschichte, 8, 1898.
HASSE, C. Anatomische Studien, 1.
HINSBERG, V. Entwick. der Nasenhohle bei Amphibien. Archiv. mikr.

Anat., 58, 1901.
KINGSBURY, B. F. Lateral-line sense-organs in American Amphibians.

Trans. Amer. Micros. Socy., 17, 1896.
KINGSLEY, J. S. The Ossicula auditus. Tufts College Studies, no. 6,

1899.

LAUBER, H. Auge von Cryptobranchus. Anat. Hefte, 20, 1902.
RETZIUS, G. Das Gehororgan der Wirbelthiere. I. Fische und Amphi-
bien. Stockholm, 1881.
SEYDEL, G. Nasenhohle und das Jacobson'sche Organ der Amphibien.

Morph. Jahrbuch, 23, 1895.

REESE, A. M. Eye of Cryptobranchus. Bioi. Bulletin, 9, 1905.
LOEB, C. Some cellular changes in primary optic vesicle of Necturus.

Jour. Comp. Neurol., 15, 1905.

DIGESTIVE SYSTEM

BATES, G. A. Histology of the digestive tract of Amblystoma. Tufts

College Studies, no. 8, 1904.
BENSLEY, R. R. (Esophageal glands of Urodcla. Biolog. Bulletin, 2,

1900.
CHORONSHITZKY, B. Entstehung der MHz und dcs dorsalcn Pankreas

bei Necturus. CR. 12 Internat. Med. Congress, Moscow, 2, 1898.
EYCI.ESHYMER, A. C. Growth and regeneration of gills in young Necturus.

Biol. Bulletin, 10, 1906.
GAGE, S. H. Epithelium of Mouth of Necturus and Menopoma. Proc.

Am. Sory. Micros., 1885.
GOPPERT, E. Entwickelung und Vcrhalten des Pankreas bei Amphibien.

Morph. Jahrbuch, 17, 1891.
HERTWIG, O. Zahnsystem der Amphibien, u.s.w. Archiv. mikr. Anat.,

11 Suppl., 1874.

NECTURUS 27

KALLIUS, E. Entwicklung der Zunge. Anat. Hefte, 16, 1901.
KINGSBURY, B. F. Histology of the enteron of Necturus. Proc. Amer.

Micros. Socy., 16, 1894.
MAURER, F. Schilddrusc, Thymus und Kiemenreste der Amphibien.

Morph. Jahrbuch, 13, 1887.
PLATT, J. B. Development of thyroid and suprapericardial bodies in

Necturus. Anat. Anzeiger, 11, 1896.

RESPIRATORY ORGANS

BRUNER, H. L. Muskelapparat zum Schliessen und Offnen der Nasen-
locher bei den Salamandriden. Archiv Anat. u. Physiol., Anat. Abth.,
1896.

Smooth facial muscles of Anura and Salamandrina. Morph. Jahr-
buch, 29, 1901.

CLEMENZ, P. Die ausseren Kiemen der Wirbelthiere. Anat. Hefte, 5,
1894.

MILLER, H. S. Structure of the lung. Jour. Morphol., 8, 1893.

OCHSNER, H. W. The lung of Necturus. Bull. Univ. Wisconsin, No.
33, 1900.

WILDER, H. H. The Amphibian larynx. Zool. Jahrbuch, Anat. Abth.,
9, 1886.

Pharyngocesophageal lung of Desmognathus. Amer. Naturalist, 35,

1901.

CIRCULATORY SYSTEM

BETHGE, E. Blutgefdsssystem von Salamandra, Triton und Spelerpes.
Zeitsch. wiss. Zool., 63, 1898.

BOAS, J. E. V. Conus arteriosus und die Arterienbogen der Amphibien.
Morph. Jahrbuch, 7, 1881.

Angiologie der Amphibien. Morph. Jahrbuch, 8, 1882. Arterien-
bogen der Wirbelthiere. Ibid., 13, 1887.

BRACKET, A. L'appareil vasculaire sanguin chez les Amphibiens. Ar-
chives de Biol., 19, 1903.

CLAYPOLE, E. J. Blood of Necturus and Cryptobranchus. Proc. Am.
Micros. Socy., 15, 1893.

GREIL, A. Anat. u. Entwick. des Herzens und des Truncus arteriosus
der Wirbeltiere. Morph. Jahrb., 31, 1903. (See also, for lymph
hearts, Verhandl. Anat. Gesellsch., 17, 1903.)

HOCHSTETTER, F. Venensystem der Amphibien und Fischen. Morph.
Jahrbuch, 13, 1888. (See also 21, 1893.)

MAURER. F. Die Keimen und ihre Gefdsse bei Amphibien. Morph.
Jahrbuch, 14, 1888.

28 GUIDES FOR VERTEBRATE DISSECTION

MILLER, W. S. Blood and lymph vessels of lung of Necturus. Amer.

Jour. Anat., 4, 1905. (See also 2, 1903.)

RABL, C. Bildung des Herzens der Amphibien. Morph. Jahrb., 12, 1887.
REX, H. Hirnvenen der Amphibien. Morph. Jahrb., 19, 1892.
SANTHOFF and VORHIS. Vascular system of Necturus. Bull. Univ.

Wisconsin, no. 33, 1900.

UROGENITAL SYSTEM.

i
BLANCHARD, R. Glandes cloacales et pelviennes . . . des Batraciens

Urodeles. Zoolog. Anzeiger, 4, 1883.

FIELD, H. H. Development of pronephros and segmental duct in Am-
phibia. Bull. Mus. Comp. Zool., 21, 1891.
Morphologic der Amphibien Harnblase. Morphol. Arbeiten, 4, 1894.

(See also Bull. Soc. Zool. France, 19, 1894, and Anatom. Anzeiger,

9, 1894.)
HALL, R. W. Development of mesonephros and Mullerian ducts in

Amphibia. Bull. Mus. Comp. Zool., 45, 1904.
KINGSBURY, B. F. Spermatheca and methods of fertilization in some

American Salamanders. Proc. Am. Socy. Micros., 17, 1895.
RUCKERT, J. Entwickclung der Exkretionsorgane. Ergebnisse Anat.

u. Entwick., 1, 1892.
SEMON, R. Bauplan des Urogenitalsystems der Wirbclthiere. Jena.

Zeitschr., 26, 1891.
SPENGEL, J. W. Urogenitalsystem der Amphibien. Arbeiten a. d. Zool.

Inst. Wiirzburg, 3, 1876.
WILSON, G. Development of Mullerian duct of Amphibians. Trans.

R. Socy. Edinburgh, 38, 1896.

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