HANDBOOK OF

VERTEBRATE DISSECTION

| PART I.
HOW TO DISSECT A CHELONIAN

H, NEWELL MARTIN

AND

W. A. MOALE

MACMILLAN AND ©O,

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Reer, A HANDBOOK

OF

VERTEBRATE DISSECTION. ,

BY

H. NEWELL MARTIN, DSc, MAA,

PROFESSOR IN THE JOHNS HOPKINS UNIVERSITY,

AND

- WILLIAM A. MOALE, M.D.

, Pere: F.
HOW TO DISSECT A CHELONIAN.

=o INST! HTUTION
LIBRARIES

NEW YORK:
MACMILLAN AND CO.
1881.

MPANY

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CopyrIGHT, 1881,
BY
MACMILLAN & CO.
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PREFACE.

Tue following pages, which contain directions for the
practical study of the anatomy of a Chelonian, are
the first instalment of a series which has had its origin
in my own needs as a teacher, and which, when com-
pleted, will form a Handbook of Vertebrate Dissection.

Some years ago Professor Huxley published a little
book called ‘‘ Practical Biology,” in the preparation of
which it was my good fortune to assist him. That book
was designed to give students commencing the study
of biology a good knowledge, based on their own ob-
servations, of the structure and life-history of a number
of typical plants and animals, with the object of laying
a firm foundation for the further study of animal or
vegetable morphology or physiology : it was, so far as
I know, the first important educational step taken in
recognition of the fact that there is a science of living
beings, as such, quite apart from any division of them
into animals and plants; and that the accurate observa-
tion of the phenomena presented by living forms of
matter of all varieties forms the basis of one single
science. This truth had, of course, been recognized
long before, and was accepted by nearly all scientific

iV PREFACE.

naturalists, but no really important step toward organ-
izing the teaching of biology in accordance with it had
previously been taken.

In the past five years, during which I have been
responsible for the direction of biological studies in
the Johns Hopkins University, I have endeavored to
arrange the curriculum so as to ensure that each stu-
dent, before taking up any one branch of biology for
special study, shall have acquired a fairly good knowl-
edge of what may be called general biology. No un-
dergraduate is permitted to devote his time to the
study of botany, or animal morphology or physiology,
until he has spent at least one year in learning some-
thing about animals and plants in general. Such a
course is indisputably far better than one more specially
botanical or zodlogical for those who merely desire
some knowledge of biological science as a part of
general education ; and I have been yearly more firmly
convinced that it affords also the best beginning for
the student who desires to become ultimately a botanist,
zoologist, or physiologist.

While the general structure of all plants can be fairly
well understood after the careful examination of a small
number of selected types, this is not the case with ani-
mals; and I have accordingly found it necessary to
‘include in the annual course several types, especially
vertebrate, not described in the ‘‘ Practical Biology.”
Of these a Chelonian is much the most difficult to dis-

PREFACE: —

sect; and, partly forthis reason, partly because the great
persistence of vitality in its various organs after general
death of the animal makes it extremely promising for
physiological experiment, it was the one for whose
dissection I first drew up laboratory directions for the
use of my students. Finding them of great value in
saving time to teacher and pupil, and also in prevent-
ing the waste of material which is apt to occur when a
student sits down without specific directions to dissect
an animal whose structure is almost entirely unknown
to him, I thought they might be of use in other labora-
tories. I accordingly asked my friend and former /pu-
pil, Dr. William A. Moale, to assist me in preparing for
publication detailed directions for the dissection of a
number of vertebrate animals. The present pamphlet
will shortly be followed by two others, containing direc-
tions for the dissection of a pigeon and a rat, both of
which are well on the way toward completion. We in-
tend ultimately to include in the series a bony and a
cartilaginous fish, a lizard, and one of the large-tailed
amphibia which form such a characteristic feature of
the American Fauna.

In the present instalment of our work, Pseudemys ru-
gosa, though far from being the most widely distributed
of American Chelonia, is the species selected for de-
scription,»mainly because it is sold in the markets here’
during the winter months, and was, therefore, readily

obtainable by us. The fact that in many places this

vl ¢ PREFACE,

wart te species may not be found is of no import-
ance, as the end in view is not to provide a monograph
on any one species, but to show a student ‘‘ How to dis-
sect a Chelonian.” The members of the order are so
similar in all important points that the best method of
examining the structure of one species is the best also
for almost any other. I am not sure, in fact, that it is
not better in all cases to provide students with species
slightly different from the one described ; their atten-
tion is kept more alert when they find they cannot alto-
gether rely on the description in the book, but have to
‘look at everything carefully for themselves.

These directions for dissection are of course not
meant to be used by themselves, but to accompany
lectures on the class and order of the type described, or
the reading of a good text-book. Some knowledge of
human osteology, which affords the best starting-point
for every student of vertebrate morphology, is also

assumed.

H. NEWELL MARTIN.

BALTIMORE, July 1, 1881.

i © ON PBN TS:

ZOOLOGICAL POSITION OF THE RED-BELLIED SLIDER TER-

RAPIN, . : ‘ ‘ ‘ 2 : 2 2 :

THE ANATOMY OF THE RED-BELLIED SLIDER TERRAPIN, .

INDEX, . ; = : a . ° : . ° :

PAGE

DESCRIPTION OF THE FIGURES.

FIG. I, represents the skull viewed from the base; FIc. 2,
as seen from the left side and partly from the front; Fic. 3,
represents the roof of the skull ; and FIG. 4, the inner side of
the right half.

The references in the different figures are as follows: 1,
the premaxilla; 2, the maxilla; 3, the palate bone; 4, the
vomer; 5, the pterygoid ; 6, the basi-sphenoid ; 7, the basi-
occipital; 8, the exoccipital; 9, the opisthotic; 10, the
squamosal ; 11, the quadrate; 12, the quadrato-jugal; 13, the
jugal; 14, the post-frontal; 15, the columella auris: a thin
plate of cartilage, which covered the inner division of the
tympanum, has been removed to expose part of the columella ;
16, the parietal ; 18, foramen for exit of external carotid artery ;
19, the posterior nares; 20, part of the opisthotic ; 21, occi-
pital condyle ; 22, orbito-temporal fossa; 23, articular surface
for mandible; 25, anterior nares ; 26, supra-occipital bone ;
27, frontal bone; 28, naso-prefrontal bone; 29, prodtic ; 30,
epiotic, anchylosed to the supra-occipital ; 31, canal for entry
of carotid artery; 32, alisphenoid bone; 33, cartilaginous
inner wall of labyrinth ; 34, foramen for exit°of internal carotid
artery.

ZOOLOGICAL POSITION OF THE RED-
BELLIED SLIDER TERRAPIN.

Supkincpom, Vertebrata. Division, Sauropsida, Cuass,
Reptilia. Orper, Chelonia. Famity, Emydoide.
Genus, Pseudemys. Sprcies, rugosa,

Characters of the Sauropsida.*
1, Almost always an epidermic skeleton, in the form
of scales or feathers.

2. The vertebral centra are ossified, but have no ter-
minal epiphyses.

3. The skull has a completely sesided occipital seg-
ment and a large basi-sphenoid. There is no separate
para-sphenoid in the adult. The prodtic is always ossi-
fied, and either remains distinct from the opisthotic
and epiotic during life, or unites with them only after
they have anchylosed with adjacent bones.

4. There is always a single convex occipital condyle,
into which the ossified ex-occipitals and basi-occipital
enter in various proportions.

5, A mandible is always present, and each ramus
consists of an articular ossification and several mem-
brane-bones. The articular is connected with the rest
of the skull by an ossified quadrate. .

6. The apparent ankle-joint lies between the proxi-
mal and distal divisions of the tarsus.

* The characters given are taken, with slight modification, from Huxley.
I

2 ANATOMY OF A CHELONIAN.

7. The alimentary canal terminates in a cloaca.

8. The heart is trilocular or quadrilocular ; some of
the blood-corpuscles are red, oval, and nucleated.

9. The aortic arches may be two or more ; when only
one persists in the adult it is on the right side.

10. Respiration is never performed by branchiz ; and
after birth always by lungs, in which the bronchi do not
branch dichotomously.

li, A thoracic diaphragm may exist, but never forms
a complete partition between the thoracic and abdomi-
nal viscera.

12. The cerebral hemispheres are never united by a
corpus callosum.

13. The reproductive organs open into the cloaca.
The oviduct is a Fallopian tube with a posterior uter-
ine dilatation.

14. There are no mammary glands.

15, All are oviparous or ovo-viviparous.

16. The Wolffian bodies are replaced functionally by
permanent kidneys.

17. The embryo has an amnion and a large respira-
tory allantois ;and develops at the expense of a large
mass of food stored up in the egg.

-

Characters of the Reptilia, as distinguished from Aves,
the remaining class included in the division Sau-
ropsida.

1, Exoskeleton composed of horny plates (epidermic),
or bony plates (dermic), or both. The epidermic scales
never develop into feathers.

2. The vertebral centra may be amphi- or pro- or

CHARACTERS OF REPTILIA. 3

opistho-ccelous, or have flat faces ; but their ends are
never cylindroidal.

3. When a sacrum is present its vertebrze have large
expanded ribs, with the ends of which the ilia articu-
late. |

4. The sternum, when present, is rhomboidal ; and,
when many ribs are connected with it, the hindermost
are attached to a single or double backward median
prolongation. The sternum may be converted into
cartilage-bone, but.is never replaced by membrane-
bone, and does not ossify from two or more definite
centres.

5. When an interclavicle exists it remains distinct
from the clavicles.

6. The manus contains more than three digits ; and,
at fewest, the three radial digits have claws.

7. The ilia are prolonged farther behind the ace-
tabula than in front of them, and the inner wall of the
acetabulum is wholly or almost wholly ossified. The
pubes are directed ventrally and forward, and, like the
ischia, meet in a ventral symphysis.

8. The digits of the pes are not fewer than three ;
the metatarsals are not anchylosed together or with the
distal tarsal bones.

9. Not fewer than two aortic arches persist. Two
arterial trunks are given off from the right ventricle, or
the part of the single ventricle that answers to it. The
venous and arterial currents are connected in the heart,
or at the origins of the aortic arches.

10. The blood varies in temperature with the sur-
rounding medium. There are usually two semilunar
valves at the origin of the aortic and pulmonary trunks.

4 ANATOMY OF A CHELONIAN.

11. The corpora bigemina lie on the dorsal aspect of
the brain. The spinal cord presents no sinus rhom-
boidalis.

12, The caudal vertebrz often form a series equal
in length to the rest of the body.

13. Teeth are frequently present.

Characters of the Chelonia,

1. None of the vertebrze have transverse processes,
and the dorsal vertebrze are not movable on one
another ; nor are the ribs movable upon the vertebra.
Most of the dorsal vertebrze and ribs are restrained from
motion by the union of superficial bony plates, into
which they pass, to form a carapace.

2. All but the soft tortoises (Z7zonyx) have part of
the epidermis modified to form horny plates, which
constitute the tortoise-shell. These plates are arranged
in definite series on the carapace and plastron.

3. The presacral vertebrz are few.

4. No sternal ribs, and no trace of a true sternum.
The ventral surface is protected by a number (usu-
ally nine) of dermal membrane bones, forming the
plastron.

5. The sacrum consists of only two vertebre ; the
sacral ribs are not anchylosed to their vertebrz.

6. The anterior caudal vertebrz have no transverse
processes, but some have ribs.

7. In the skull, all the bones but the mandible and
hyoidean arch are immovably united together: the
epiotic anchyloses to the supra-occipital ; the prodtic
and opisthotic remain as distinct bones. The alisphe-

CHARACTERS OF CHELONIA. 5

noid is unossified or small, a downward prolongation
of the parietal taking its place. There is no bony pre-
sphenoid or orbito-sphenoid. The mesethmoid carti-
lage largely persists. The orbito-temporal fossa is
covered by a bony arch. The dentary pieces of the
mandible are anchylosed together.

8. The pectoral arch is ossified in such a way that
scapula and precoracoid form one bone, but the cora-
coid remains distinct.

9. The heart has a single ventricle.

10. There are no teeth, but the jaws are provided
with horny cutting-plates.

Fog

THE ANATOMY OF THE RED-BELLIED
SLIDER TERRAPIN (Pseudemys rugosa).*

1. General External Appearance.—Note the hard case
in which most of the animal is enclosed, and which va-
ries in tint considerably in different specimens ; on the
whole it is dark brown above, and orange-red and yel-
low beneath.

The case consists of a convex dorsal plate, the cara-
pace, and a ventral flat plate, the plastron, united at
the sides by bony bridges, but separate anteriorly and
posteriorly, leaving large open spaces, in which can be
seen certain soft parts covered by wrinkled, scaly skin,
and protected by the projecting edges of the carapace
and plastron.

Most of the skin is dark, with bright yellow stripes ;
but in the hollows which receive the hind limbs when
withdrawn, and often also in the corresponding hol-
lows for the fore limbs, it is almost white.

2. Insert a tenaculum into the soft parts beneath the
head and draw out the latter; force open the mouth
and direct a pipette, containing about a teaspoonful of
chloroform, into the opening of the glottis, which will
be found in an elevation at the base of the tongue ;
then blow the chloroform into the lungs. This will
very soon kill the animal. Meanwhile, note the long,

* Ptychemys rugosa (Ag.). mys rubriventris (Holbr.).

EXTERNAL CHARACTERS. VA

flexible neck, the folds of skin about the shoulders,
and, after the tenaculum is removed, the way the head
is withdrawn between these folds, so that only the tip
of the snout is visible. So soon as the animal is dead
and flaccid, you can readily stretch out the neck and
proceed with your examination.

+ ‘External Characters of Head and Neck,

a.

Observe the form of the head: flattened from
above down ; wide posteriorly, where it is very
distinctly differentiated from the neck; and
narrowing toward the snout.

On the ventral aspect of the head and neck
the hyotdean apparatus can be felt through the
skin of the throat; and farther back the wind-
pipe.

The very large mouth opening, provided with
notched horny plates instead of teeth along
the margins of the jaws; note the marked
projection on each side of the median notch
of the upper jaw.

On the extremity of the snout the openings
of the anterior nares ; a pair of round apertures
placed close together.

The eyes, around which can be felt the ante-

-rior margins of the bony ordits; the thick,

opaque upper eye/zd, and the larger, more movy-
able lower one; the wictitating membrane, or
third eyelid, may be found covering the eye-
ball or withdrawn to the anterior corner of the
eye opening ; in the latter case seize its mar-
gin with forceps and draw it back over the
eye so as to see it well; it is much more

ANATOMY OF A CHELONIAN.

movable and less opaque than the eyelids
proper.

Just behind the angle of the gape, the tym-
panic membrane will be seen as a circular
slightly depressed area of skin, around the
margin of which a hard supporting ring can
be felt.

4. The Interior of the Mouth Cavity.

a.

Open the mouth and observe that the horny
plates covering the jaws extend in for some
way-over both floor and roof of the buccal
cavity ; also that each has a second notched
ridge within the one forming its outer boun-
dary. Into the groove between the two up-
per ridges the external lower ridge fits, and
similarly the inner ridge of the upper jaw fits
between the two ridges of the lower.

On the roof of the mouth, note that the horny
plate is succeeded by diverging folds of mu-
cous membrane, between which are seen the
openings of the posterior nares with the back
edge of the septum narium between them. Note
also that the eyeballs do not cause projections ~
on the roof of the mouth, as in the frog, but
are completely separated from it by a hard
partition.

On the floor of the mouth is seen the short, con-
ical, pointed, and but slightly movable ‘ongue.
At the base of the tongue is a considerable
elevation, in which is the longitudinal slit of
the aditus laryngis, unprotected by an epi-
glottis.

A EXTERNAL CHARACTERS. 9

d. On each side of the mouth cavity, behind
the elevation caused by the mass of muscles
passing down to the lower jaw, is the small
opening of a Lustachitn tube. It will be found
more easily later (177, 2).

5. The Limbs.

a. Note the manner in which the limbs, when
not in use, are packed away between the
projecting edges of carapace and plastron, in
hollows at the sides of the neck and pelvis.

b. The fore limbs are flattened, clumsy, and pad-
dle-like. When extended they curve back
over the front edges of the bridges which unite
carapace and plastron. The division into dra-
chium, antebrachium, and manus is not obvious
to the eye, but may readily be felt. The limb
ends in five digits, connected by a web, and
each armed with a large claw.

c. The hind limbs show more plainly the division
into femur, crus, and pes. Each terminates in
five digits united by a web, and possessing
claws, except the fifth.

d. Seizing the pelvic region between finger and
thumb, note that it has a considerable range of
lateral sway. This movement takes place at
the articulation between the last dorsal and
the first sacral vertebra, and to some extent
compensates for the rigidity of the whole dor-
sal region of the animal.

6. The tail, short, conical, and pointed ; usually bent
to one side, so as to be protected by the overlapping

edge of the carapace.
1*

IO ANATOMY Of A CHELONIAN.

On its under surface is the cloacal opening ; a trans-
verse slit, with puckered edges.

7. The Epidermic Exoskeleton mainly consists of horny
plates (tortoise-shell), of definite number and very con-
stant arrangement, found covering carapace and plas-
tron.

a.. On the plastron are sixteen pieces, twelve ar-
ranged in pairs on the sides of the middle line,
and the remaining four covering the margins
of the bony bridges uniting carapace and plas-
tron.

6. Onthe carapace, in the middle line in front, is
a small xuchal plate ; and, meeting in the mid-
dle line behind, over the base of the tail, are a
pair of pygal plates. Running along the middle
of the back, from nuchal to pygal plates, are five
unpaired central plates. On each side of the
latter are four centro-lateral plates; and, external
to these, eleven marginal plates on each side, ex-
tending along the edge of the carapace from
the nuchal to the pygal plates, and, like them,
curving around the edge so as to cover in the
projecting margin of the carapace on its ventral
side. :

c. The claws, the horny coverings of the jaws, and
the scales (which are’ especially developed on
the paddles and the dorsal side of the tail) are
also parts of the epidermic exoskeleton.

8. Make drawings showing the arrangement and form
of the epidermic plates on carapace and plastron. Then
immerse the animal in boiling water for about two min-

THE CARAPACE. atl: II

utes, giving first another dose of chloroform (2) should
there be the least sign of sensibility remaining ; the tor-
toise-shell can then be peeled off. When it is removed,
note that though the bones beneath present surface-
markings corresponding to the edges of the epidermic
plates, their actual number and arrangement are quite
different..

9. The Bony and Cartilaginous Skeleton.—For the sat-
isfactory study of the skeleton, the student should have
. beside him a prepared articulated skeleton for reference,
and should disarticulate and examine another skeleton
for himself. For this purpose boil the animal thor-
oughly ; the plastron can usually then be separated from
the carapace by seizing each and pulling them forcibly
apart ; if this prove impracticable, divide the uniting
brifges by a saw, then cut through the soft parts at-
tached to the dorsal aspect of the plastron and remove
the latter; clean all the bones carefully, but for the pre-
sent do not separate from one another the pieces of
the plastron, carapace, skull, manus, and pes. In the
cleaning take great care not to injure the cartilaginous
portions of the skeleton.

10. The Carapace is composed partly of dermic exo-
skeletal bony plates, and partly of true endoskeletal
elements. The dermic bones are printed below in small
capitals.

a. Qn the exterior of the carapace, note a median
row of bones succeeding one another, from be-
fore back, in the following order: the Nucuau
Pate, rhomboidal in shape ; eight xewral plates,
formed by the expanded spines of the dorsal

12

ANATOMY OF A CHELONIAN. ©

vertebrze from the second to the ninth, inclu-
sive ; the PyGaL PLATE.

On each side of the above middle row are eight
costal plates, formed by expanded ribs attached
to the dorsal vertebrze from the second to the
ninth. In all except old full-grown specimens
the outer ends of the costal plates are not fully
ossified ; and, accordingly, spaces filled only by
cartilage are then left between each one and its
Successor.

The MarcInat PuiaTEs, eleven on each side, ex-
tend from the nuchal to the pygal. From the
second to the fifth, inclusive, they reach ven-
trally to articulate with the plastron.

11. On the inner (ventral) aspect of the carapace, note
the projecting centra of the Dorsal Vertebre. The most
anterior is attached dorsally to the nuchal plate ; the
eight succeeding ones bear, dorsally, the expanded neu-
ral spines already seen on the exterior of the carapace
as the neural plates.

a

The first dorsal vertebra is comparatively short
and thick, and bears anteriorly a pair of large
stout presygapophyses (anterior articular processes),
which slope downward and forward.

The centra of the succeeding dorsal vertebra,
back to the eighth, are considerably elongated
in the antero-posterior axis, and compressed
from side to side. Each has flattened ends, and
between each pair lies a thick plate of cartilage,
except in quite old specimens in which the
intervening cartilage is much thinner. The
whole set of dorsal vertebral centra, with these

THE CARAPACE, — 13

plates, thus forms a continuous osseo-cartila-
ginous rod.

12. Examine the Ribs,—Attached opposite the inter-
spaces between the vertebral bodies from the first to the
fourth dorsal, and articulating either only with the inter-
posed cartilage, or also with the posterior end of one
centrum and the anterior end of the next, are the
heads (capitu/a) of the second, third, and fourth ribs.

a, From the capitula, thin bony bars, which may
conveniently be called the wecks of the ribs, run
outward and dorsally for a short distance, and
then fuse with the ventral aspect of the costal
plates already mentioned (10, 8).

4. The costal plates by their inner ends articulate
with the neural plates of the two vertebrz be-
tween which the head of the corresponding
rib lies.

. .

13. The arrangement of the fifth, sixth, seventh, and
eighth ribs is like that described above (12), except
that each articulates with the centrum of only one dor-

sal vertebra (that which corresponds ‘in number with
the rib); and the costal plate of the ninth rib articu-
lates only with the neural plate of its own vertebra.
In old specimens, also, the sides of the centra of the
posterior dorsal vertebrae bear distinct capitular pro-
cesses, to the ends of which the heads of the ribs are
attached.

14, The ribs of the first pair are very small ; they
run backward and outward from the sides of the cen-
trum of the first dorsal vertebra, and fuse at their outer

14 ‘ANATOMY OF A CHELONIAN.

ends with the costal plates of the second dorsal verte-
bra, the first vertebra having no costal plates of its
own.

15, The tenth dorsal vertebra is comparatively wide
and short, and carries a pair of small ribs which have
no costal plates of their own, but anchylose with the
eighth’ pair of costal plates (ze, those of the ninth
dorsal vertebra). On the ventral aspect of each of
these last costal plates is to be seen a small elevation,
over which the sacral ribs (16) glide in lateral move-
ments of the pelvis.

16. The two Sacral Vertebre may be found still at-
tached to the carapace, or one or both may have come
away with the tail in preparing the specimen. Each
has a pair of short ribs, which run outward and end in
cartilages—which, in the articulated specimen, will be
seen to articulate with the iliac bones (71, a). That
end of each rib next the vertebral centrum is also car-
tilaginous. The anterior rib is much stouter than the
other.

17. Take the carapace to bits, piece by piece, noting
meanwhile the finely dentated sutures by which most of
the bones articulate. As you separate the pieces, note
also that—

a. The neural arch of the first dorsal vertebra
is much shorter than the centrum, which is
overlapped in front by the posterior end of
the nuchal plate, and behind by the neural
plate of the succeeding vertebra, the spine of
the first dorsal vertebra not expanding to make

_-

THE CARAPACE, 15

any neural plate. This vertebra also has not
a persistent zeuro-central suture, the neural arch
being firmly grown into continuity with the
centrum. Its remarkable prezygapophyses,
which articulate with the postzygapophyses ( pos-
terior articular processes) of the last cervical ver-
tebra, have already been mentioned (11, a).

6, The centrum of the second dorsal vertebra is
covered on the dorsal side, for its anterior two-
thirds, by its own neural arch, the two uniting
by a persistent xeuro-central suture ; the pos-
terior third of the centrum is overlapped by,
and articulates with, the neural arch of the
vertebra behind. Its neural spine expands to
form the first neural plate of the carapace.

¢. The arrangement of the parts of the dorsal
vertebrze from the third to the eighth, inclu-
Sive, is pretty much like that found in the
second ; but in each the neural plate reaches
as far back as the posterior margin of the cen-
trum, although the /amine of the neural arch
of the ninth vertebra overlap the posterior
part of the centrum of the eighth.

@ The neural plate of the ninth dorsal vertebra
reaches back and overlaps the tenth vertebra,
which has no neural plate of its own.

18. Examine carefully a Costal Plate—the third, for
example. Note the dentated sutures on each of its
margins ; the continuity of the neck of a rib with its
ventral surface ; the process which extends from its
outer end to be inserted into a pit in the corresponding
marginal plate. In partly grown specimens this process

16 ANATOMY OF A CHELONIAN.

is long and conspicuous, the portions of costal plate in
front of and posterior to it in that region being not yet
ossified (10, 0).

Also, examine more carefully the marginal plates
now that they are separated ; and note their relations
to the various costal plates.

19. The Plastron. is composed entirely of: dermic
bones. It consists of nine pieces: one median un-
paired bone toward its anterior end, called the ENTO-
PLASTRON ; and eight bones arranged in pairs on each
side of the median line ; those on each side, from be-
fore back, are named successively, EPIPLASTRON (? clav-
icle), HYOPLASTRON, HYPOPLASTRON, and XIPHIPLASTRON.
The outward ends of the hyo- and hypo-plastron curve
dorsally, and make up most of the-bony bridges-uniting
carapace and plastron.

20. The Cervical Vertebre are eight in number and
freely movable, except the first and second. In gen-
eral, each consists of a centrum and neural arch, with
pre- and post-zygapophyses; and the articular surfaces
of the prezygapophyses look dorsally, and those of
the postzygapophyses ventrally; there are no trans-
verse processes, but the arches present more or less
of a median dorsal ridge, representing a rudimen-
tary spinous process. The posterior end of the body
is produced backward and ventrally some distance be-
yond the neural arch; and the intervertebral foramina
are arched over by the articular processes. The centra
bear a slight median ridge on the ventral aspect, and
are thick and cylindrical near the anterior end, but
flattened dorso-ventrally at the posterior.

THE CERVICAL VERTEBRE. tz

21. In individual cervical vertebrz, note the follow-
ing peculiarities :

a.

The first (atlas) is a ring-like mass, composed of
three pieces: a ventral and two dorso-lateral,
united by cartilages. Its anterior end presents,
where the three pieces meet, a deep pit, in
which the occipital condyle (25, a) plays ;_ pos-
teriorly is a similar pit for the odontoid pro-
cess of the axis (21, 4).

The second cervical vertebra (axis) has a large
odontoid process, attached by cartilage to the
anterior end of its centrum.

The postzygapophyses of the seventh and eighth
cervical vertebre are remarkably large and stout,
and those of the eighth arch backward to ar-
ticulate with the prezygapophyses of the first

' dorsal vertebra (11, a). These two vertebrz

are also peculiar in their neural spines, which
consist of a pair of ridges which meet ante-
riorly, but diverge behind to run out over the
postzygapophyses.

The variety in the surfaces by which the cen-
tra of the cervical vertebrz articulate with
one another. The second and third vertebrz
are opistho-celous ; the fourth has a convexity
on each end of its centrum; the fifth is con-
cave anteriorly, and has a pair of convexities
behind. The sixth has two concavities in
front, and two convexities behind. The sev-
enth has two concavities in front, and two
behind. The eighth has two convexities in
front and two behind.

18 ANATOMY OF A CHELONIAN.

22, The Caudal Vertebre are freely movable, and in
the anterior part of the tail proccelous. From the fifth
to the tenth, inclusive, they have well-marked rudimen-
tary ribs attached to them. None have transverse pro-
cesses. Becoming smaller and smaller toward the tip
of the tail, they are finally reduced to minute subcy-
lindrical masses, without any processes, but each still
possessing a centrum and a neural arch enclosing a
neural canal.

23. The Skull.—After boiling the skull, clean away the
soft parts, taking care to leave, in so doing, as much
of its cartilaginous parts as possible—the thin plate
between the nostrils is especially apt to be removed.
When cleaned, make outline drawings of the skull, as
seen from behind, from the base, and antero-laterally.

24, The skull is flattened from above down, and
wide from side to side. Note that the brain-case proper
is much narrower than the skull, which is expanded
posteriorly, to form a pair of large post-auditory processes,
from which two bony arches proceed forward on each
side : one below the orbit to the upper jaw, and the
other behind the orbit to the brain-case proper. The
temporal fossa is covered in by this arch on each side,
and is continuous with the orbital cavity, so that the
two form one orbito-temporal fossa.

25. On the Posterior Aspect of the Skull, note:
a. The foramen magnum, and below it the single
occipital condyle. ;
&, On each side of the condyle are two sen
foramina; through the more mesial of these,

the hypoglossal nerve (180, ¢) passes out.

THE SKULL. xg

External to these is the larger foramen lacerum
posterius, which gives exit to the pneumogas-
tric and spinal accessory nerves (180, /).

Still farther out is seen the conical post-auditory
process, covered over by the sguamosal bone.
Above the foramen magnum the bony spine of
the supra-occipital bone projects backward ; on
each side of this the roof of the skull is con-
cave, and in the bottom of the hollow is a
large foramen, through which the external caro-
tid artery passes out to supply the exterior of
the head.

26. On the Base of the Skull, note:

a.

The ventrally projecting guadrate bone, with its
terminal facet for articulation with the mandi-
ble.

Farther forward, and near the middle line
the posterior nares, and somewhat behind and
to the outside of these, the aperture on each
side for the transmission of a branch of the
fifth cranial nerve.

In front of the quadrate a large aperture leads
up into the orbito-temporal fossa; through it
the main muscles of mastication formerly
passed to the lower jaw from their origins on
the sides of the brain-case.

Behind the quadrate is a plate of cartilage,
ossified in some specimens, which is often re-
moved in cleaning the skull; if this’ has not
happened remove it now on one side. This
will lay open part of the labyrinth and the inner
section of the tympanic cavity, which will be

20

ANATOMY OF A CHELONIAN.

seen to communicate with an outer division

by means of a narrow passage, through which

the columella aurts (now exposed 77 situ) passes

from the tympanic membrane on its way to

the fenestra ovalis.

Just outside the cartilaginous plate referred to
above and close behind the quadrate is a fora-

men for the entry of the carotid artery, which,

within the bone, divides into an zuternal carotid,

which enters the skull cavity, and an external
carotid, which emerges by the foramen on the

roof of the skull mentioned above (25, ¢).

In front of the cartilage, and nearer its outer
than its inner side, is a small aperture which

leads into a canal which passes forward some

way in the bone forming the base of the skull.

Into it one division of the anterior extremity
of the sympathetic nerve will subsequently
(199) be found to pass.

External to the aperture of the sympathetic

channel, and in front of the aperture of the

carotid canal, is the small foramen of exit for
the seventh cranial nerve (200).

277. On the Side of the Skull, note:

a.

The large ear-opening leading into the external
division of the tympanum, which reaches back
into the post-auditory process. Close to the
outer side of the proximal end of the quadrate
bone is the narrow passage through which the
columella passes on to the inner expansion of
the tympanic cavity.

Farther forward is the temporal fossa covered

THE SKULL, 25

over by the arches already mentioned (24). In
it, just above the inner side of the proximal
end of the quadrate bone, is the large foramen
through which the superior and inferior maxil-
lary divisions of the fifth cranial nerve leave the
skull (190, 191).

28. Note that the anterior end of the brain-case
proper is not inclosed by bone, but opens widely be-
tween the orbits ; also, that between the orbits there is
no bony partition, the zxter-orbital septum being nearly
entirely membranous, and usually removed in cleaning
the skull. In the middle line between the orbits and
close to the bone bounding them below, will, however,
be found the xaso-ethmoidal cartilage, passing out from
the interior of the skull-chamber and there flattened
dorso-ventrally ; between the orbits it becomes cylin-
drical, and then, farther forward, expands into a verti-
cal plate (mesethmotd), which enters the nose and forms
most of the partition between the nostrils.

29. The floor of the orbit isnot completely bony, but
’ presents a considerable fontanelle, closed in the recent
state by membrane: through this a branch of the su-
perior maxillary nerve will subsequently (190) be found
to pass.

30. On the posterior boundary of the nares, note a
round aperture above the mesethmoid cartilage, and
close to the roof of the nose. Into it, in the recent
_ state, reached an anterior prolongation of the brain, en-
veloped in dura mater (169), which passed out of the
large anterior opening of the proper brain-case above

22 ANATOMY OF A CHELONIAN.

noted (28), and, thence, forward between the eyeballs
and close to the bones on the roof of this part of the
skull.

31, If necessary, now boil the skull again until its
bones are readily separable. Then, working with the
articulated specimen beside you for reference, remove
the bones, one by one, in the order in which they are
described below ; as each is removed, and its boundaries |
thoroughly ascertained, sketch it in on your outline
drawings (23).

32. The fost-fronial is an irregular, squarish bone
which forms most of the posterior margin of the orbit ;
it articulates with the frontal and parietal above, and
jugal and guadrato-jugal below. A long process reaches
back from its postero-inferior margin.

33. Below the post-frontal and forming the posterior
margin of the orbit, is the juga/, squarish as seen from
the exterior, but sending inward a process which forms
part of the floor of the orbit and reaches internally to
the pterygoid. It is overlapped by the maxilla in front.
The jugal overlaps behind the bone next described.

34. The guadrato-jugal bounds the anterior margin of
the tympanic cavity. It sends downward and back-
ward a slender process, which turns around the margin
of the ear-opening for a variable extent. Posteriorly it
joins the quadrate below and the squamosal above.

35. Behind the tympanum is a conical cap of bone,
the sguwamosal, which covers a similarly shaped semi-

THE SKULL. 23

cartilaginous cap, whose hollow is continuous with the
tympanic cavity. In front, the squamosal articulates
with the quadrato-jugal and the quadrate ; and, behind,
it overlaps and conceals parts of the quadrate and opis-
thotic bones.

36. The guadrate forms a large, irregular, bony mass,
in which lies much of the tympanic cavity. It is pro-
duced ventrally to articulate with the mandible. It
articulates at its upper end, on the inner side, with the
proétic and opisthotic bones. In removing the quad-
rate, take care not to displace the columella auris.

37. The ofisthotic, which protects the posterior part
of the inner ear, may now be removed and examined ;
it forms the posterior boundary of the fenestra ovalis
(26, @). Behind, it articulates with the exoccipital ;
-above, with the supra-occipital ; and in front with the
prootic. It also articulates with the quadrate, which
conceals a great portion of it in the natural positions of
the parts.

38. In front of the opisthotic is the prodtic, bound-
ing the fenestra ovalis in front. It articulates with the
last bone ; also in the base of the skull with the basi-
sphenoid and pterygoid; and above with the parietal
and epiotic.

39. The efiotic lies above the prodtic and opisthotic,
with both of which it articulates. In adults it is not
separable from the supra-occipital. —

40. The supra-occipital bone bounds the foramen mag-
num above ; in front it is overlapped by the parietals ;

24 ANATOMY OF A CHELONIAN.

a
below it articulates with the exoccipitals and anchy-
loses with the epiotic.

Al. The exoccipital bones form the lateral boundaries
of the foramen magnum, and, together with the basi-
occipital, form the occipital condyle.

~

42. The dasi-occipital articulates on its sides with the
exoccipitals, and anteriorly with the basi-sphenoid.

43. On the base of the skull, in front of the basi-
occipital, is seen the dasi-sphenoid. It articulates with
the pterygoids in front, and the prodtics-on its sides ;
when removed, observe that its upper or inner surface
presents anteriorly a concavity (se//a turcica) bounded
by ridges, which rise up in front as a pair of thin bony
plates, the anterior clinoid processes. Posteriorly its up-
per surface presents a median ridge, continuous with
a similar one on the corresponding surface of the basi-
occipital. ; |

44. In front of the basi-sphenoid, and partly covering
its ventral surface, are the pterygoid bones.

45. The parietal bones form a large part of the roof
of the cranium. Posteriorly they overlap the supra-
occipitals; in front they unite with the frontals; in
the middle line they meet one another; laterally, they
reach down and cover in much of the sides of the brain-
case proper, meeting the pterygoids, palate bones, and
prodtics.

46. The great downward extension of the parietals
is a marked feature of the Chelonian skull, causing

THE: SKULL: 25

them to cover in a region which, in most cases, is pro-
tected by the alisphenoid. This bone.is small and closely
attached to the middle third of the ventral margin of
the parietal in the skull of the Slider.

AT. The palate bones lie in front of the pterygoids.
They partly bound the posterior nares above, and also
form a small part of the roof of the mouth on the sides
of the recess in which the posterior nares open. Above
they meet the pterygoids, and externally the superior
maxilla. Between them lies—

48. The vomer, a slender bone having on its anterior
extremity a knob which appears on the roof of the
mouth. With the palate bones it completes the roof
of the posterior nares.

- 49. Meeting in the middle line at the front of the
skull are the small premaxille, which bear part of the
horny cutting-ridges of the upper jaw.

50. The maxil/e lie on the outer sides of the pre-
maxillz, and form the greater part of the roof of the
mouth and of the upper boundary of the gape; they
also form a large part of the floors of the orbits.

D1. The zaso-prefrontal bones roof in the front part of
the nose chamber. In front they join the maxillez, and
help to complete the orbital boundary. Behind they
join—

52. The frontal bones, which meet in the middle line
above the orbits. Behind, these articulate with the
parietal and post-frontal bones, and in front with the
naso-prefrontal bones.

z

\

26 ANATOMY OF A CHELONIAN.

53. The Mandible is a V-shaped mass, composed of
several bones, and presents an anterior dorso-ventrally
compressed éody, and two lateral ram, one at the poste-
rior end of each half of the body, and compressed later-
ally. On the upper border, on each side, isa prominent
coronoid process where ramus and body meet; and on the
free end of the ramus is an oblique surface, with a cen-
tral elevation, which articulates with the ventral end of
the quadrate (36), which has a corresponding groove
into which the ridge fits, so that a firm hinge-joint is
formed between them. On the upper surface of the
body are ridges, which bear the horny cutting plates
of the lower jaw (4, 2). On the upper edge of the ra-
mus is a fissure leading into the mandible ; a branch of
the inferior maxillary nerve (191) enters there. On the
inner side of the ramus are two foramina; through the
lower a branch of the above nerve passes out into the
floor of the mouth.

54. The following parts enter into the composition
of the mandible ; to separate them needs some patience,
as the bones adhere very tightly and the lines of artic-
ulation are not very visible.

a. On the posterior aspect of the bony body of
the mandible is a groove, filled in the recent
skeleton by a cartilaginous rod (MMeckel’s
cartilage), which will subsequently be found
to extend back through the rami.

b. Take hold of the articular end of one ramus,
and work it to and fro until it is loose. Then
carefully detach it, disturbing the remaining ~
bones as little as possible. It will bring with
it Meckel’s cartilage, which will be found to

é.

d,

%

I.

h.

THE SKULL, 27

join its fellow in the middle line in front; di-
vide the cartilage at this point, and remove
the whole loosened piece; it consists of four
bones, which are to be separated and exam-
ined.

One of these pieces, placed to the outside, and
forming the outer boundary of the fissure
above mentioned (53), is a thin bone, lying in
the vertical plane; it is the surangular. In the
natural position of the parts it is largely over-
lapped by the dentary (54, %).

Forming the inner boundary of the fissure, and
reaching back to form part of the surface which
articulates with the quadrate, is another thin,
flat bone, placed vertically : it is the splenzal,
and forms nearly all the inner surface of the
ramus of the mandible.

Wedged in between the lower edges of the

- splenial and surangular is a narrow bony bar,

the os angulare.

When the above pieces are removed, Meckel’s
cartilage will be left, with a small polygonal
bone continuous with its posterior end. This
bone is the os articulare. It forms most of the
articular facet of the mandible, and is the only
part of it ossified in cartilage.

The part of the mandible left when the above
lq@osened portion (54, 2) was removed, contains
_two bones: one is the coronotd, which forms
‘the process of that name (53), and articulates

in front with—

The dentary, which is anchylosed to its fellow

in the middle line in front, and also sends back

28 ANATOMY OF A CHELONIAN.

a process on the outside of the ramus, overlap-
ping the surangular.

55. The bones of the skull, seen in their natural rela-
tive positions from the interior of the cranial cavity,
may be studied either on one-half of a prepared median
dorso-ventral section of the cranium, or, better, on a
recent specimen prepared by the student; as the carti-
laginous parts, which are important, are apt to be re-
moved unless special care has been taken in preparing
the specimen.

56. On the Interior of the Skull, as viewed from one
side, note :

a. The dbast-occipital bone, divided by the saw in the
median line behind.

6. External to the basi-occipital, the exoccipital.
having in it the foramen (25, 4) for the twelfth
cranial nerve ; between it and the basi-occi-
pital another foramen ; and between it and the
opisthotic the foramen of exit for the vagus
and spinal accessory nerves (25, ¢).

c. Above the exoccipital the large supra-occipital,
with its spine. |

@d. On the base of the skull, and in front of the
basi-occipital, the divided dasi-sphenoid, with its
median ridge and one of the clinoid processes
described above (43); and in front of the cli-
noid process a hollow from which some mus-
cles of the eyeball (184) arise.

e. External and dorsal to the outer edge of the
posterior portion of the basi-sphenoid is a car-
tilaginous plate (already removed if care has

S

THE SKULL. 29

not been taken in preparing the skull), which
separates the cranial cavity from the internal
ear. The extent of this plate varies very much,
being less in older specimens. The corner of
the supra-occipital which bounds it above, rep-
resents the epzotic bone (39).

Behind the cartilage is the ofisthotic bone, and
in front of it the prodtic.

In front of the supra-occipital and prodtic, and
also reaching back so as to cover in a part of
the supra-occipital, is the parietal bone, and be-
tween it and the prodtic, the large foramen
( foramen ovale) for the exit of the main di-
visions of the trigeminal nerve.

External to the anterior clinoid process of the
basi-sphenoid, and in the prodtic bone, is seen
the opening of the canal through which the

internal carotid artery enters the cranial cav-

ity. Pass a probe back through the canal to
the point where the common carotid artery
enters the skull cavity (26, ¢).

In front of the basi-sphenoid is seen the f/ery-
goid bone, forming that part of the base of the
skull.

External to the pterygoid, below the parietal,
and in front of the prodtic, is the small a@/z-
sphenotd bone.

In front of the descending plate of the parietal
(45) is the large aperture left by the removal of
the membranous interorbital septum in prepar-
ing theskull. Bounding it behind is the parie-
tal; above, the frontal and the naso-prefrontal
bones; in front, the naso-prefrontal; below, the

MW.

ANATOMY OF A CHELONIAN.

palate bone and the vomer, and, lying on these,
the naso-ethmoid cartilaginous rod (28).

In front of the naso-prefrontal bone is seen the
nostril cavity, bounded below by the maxilla
and the premaxilla ; externally by the maxilla
and the naso-prefrontal bone; and above, by
the latter bone.

57. The Hyoidean Apparatus is largely cartilaginous,
except in old specimens. It presents—

a.

A median piece, or Jody, with a concavity on
its dorsal side into which the larynx and the
anterior end of the trachea fit. The ventral
surface of the body of the hyoid is convex,
and its most prominent median part is com-
posed of a connective-tissue membrane. From
its anterior end arises a small median pointed
process, which, in the recent state, enters the
tongue. To each antero-lateral angle a small
cartilaginous nodule is attached: by a fibrous
membrane.

Attached to the sides of the body of the hyoid,
about half way between its anterior and pos-
terior ends, are the curved anterior cornua,
which ossify earlier than the rest of the hyoid-
ean apparatus. They run back, in their nor-
mal position, parallel with and close to the
posterior border of the mandible.

The postero-lateral angles of the body of the
hyoid form diverging processes to which the
posterior cornua are attached; they are shorter
and stouter than the iin cornua, and are
curved in the opposite direction,

THE FORELIMB., 31

58. The Pectoral Arch consists on each side of two
pieces. On the articulated skeleton note its general
position with respect to carapace and plastron, and the
attachment of the forelimbs to its outer angles,

59. One of the pieces of the pectoral arch on each
side (the scapulo-precoracoid) is V-shaped, with the angle
of the V turned outward. Its dorsal limb (scapula) is
longer than the other and attached to the ventral as-
pect of the first costal plate, opposite the first dorsal
vertébra.

60. The frecoracoid, which forms the shorter and ven-
tral limb of the V, nearly meets its fellow in the middle
line opposite the entoplastron (19) ; in the recent state,
stout ligaments attach it to the plastron.

61. The remaining bony piece of the pectoral arch
on each side is the coracoid bone ; it is somewhat flat-
tened dorso-ventrally, and passes back in a nearly hori-
zontal plane from its articulation with the scapulo-
precoracoid where the two limbs of the V formed by
the latter meet. Its posterior end is expanded.

62. Note the deep glenoid fossa where the elements
of the pectoral arch meet.

63.-When you open another terrapin (77) observe
the stout ligament joining the distal ends of coracoid
and precoracoid ; it represents the eficoracoid, found
as a distinct bone in some reptilia.

64. The Forelimb is short and stout. Note in the ar-
ticulated ‘skeleton that it lies in a nearly horizontal

32 ANATOMY OF A CHELONIAN.

plane, and, in its position of rest, with the humerus di-
rected forward and the forearm and manus backward ;
also that the two bones of the forearm lie in a dorso-
ventral plane, the ulna being dorsal. If the forelimb
were stretched out so that its axis was perpendicular
to the median antero-posterior dorso-ventral plane of
the trunk the thumb side would be ventral.

65. The humerus has a short, thick shaft with expanded
articular extremities. The proximal extremity, set on
to the shaft nearly at a right angle, has two very large
tuberosities, and articulates with the glenoid fossa. On
the distal end is the articular surface for radius and
ulna.

66. The bones of the forearm (radius and ulna) are sep-
arate and flattened, and somewhat constricted in their
median portions.- The ulna is thicker and larger than
the radius, and reaches beyond it at the elbow; at the
wrist, the reverse is the case.

67. Zhe carpus is composed of eight bones. Three lie
at the distal end of the ulna; of them, that on the ulnar
side, considerably smaller than the others (and often
removed in preparing the skeleton), is the pzstform ;
next it is the cunezform (os ulnare) which articulates on
its proximal side with the ulna; the third bone of the
proximal row is the semi/unar (os intermedium), which
articulates above with the ulna, and on its radial side
with the side of the projecting end of the radius.

68. The distal end of the radius articulates with the
proximal end of the. largest bone in the carpus, which

PELVIC GIRDLE. 33

. probably represents the scaphoid (os radiale) and os cen-
trale combined.

69. The four remaining bones of the carpus (carpalia)
lie in a row at the bases of the digits ; those correspond-
ing to the first, second, and third metacarpal bones
(trapezium, trapezoid, and os magnum respectively) are
separate ; the carpalia of the fourth and fifth digits, on
the other hand, are united to form a single bone (wcz-
form) which, however, presents a deep groove; this
indicates its primitive doubleness, and will lead to the
belief that it is made up of two distinct pieces, unless
careful examination be made.

0. Each of the five digits consists of a metacarpal
bone and three phalanges, except the first (fo//ex) and
the fifth (*znimum), which each have but two phalanges.
The terminal phalanx on each is long, curved, pointed,
and claw-like. :

Tl. The Pelvic Girdle is composed of the iliac, the
ischial, and the pubic bone on each side.

a. The tdium is attached to the sacral ribs, as de-
scribed above (16); from there the bone runs
ventro-mesially and joins the ischium and os
pubis at the acetabulum.

b. The pubic bones are flat plates, which meet ven-
trally in a mesial pudic symphysis, from which
a cartilaginous plate proceeds forward in the
abdominal wall. External to this each bone
has a large, pointed process, directed forward.

c. The ischial bones meet also in a median ven-
tral symphysis, and are much like the pubics

2*

34 ANATOMY OF A CHELONIAN.

in form, though smaller. Each reaches for-
ward so as to meet a process sent back from the
pubic bone on the same side, and enclose a
large obturator foramen. .

72. The Hind Limb, larger and somewhat stouter than
the anterior, resembles it closely in general form and
in its position with reference to the axial skeleton (64).

13. Zhe femur is larger than the humerus, but re-
“markably like it in shape.

74, In the crus the tibia and fibula are distinct, and
each enters into the knee- and ankle-joints. The tibia
is larger than the fibula, and placed on its ventral side.

75. The tarsus has two bones in its proximal row.
The larger of these (astraga/us), placed on the tibial side,
is made up of a coalesced “zbiale and intermedium. The
other bone in this row is the os fibulare (calcaneum).
The distal row of the tarsus presents five bones (¢arsa-
fia), of which that on the fibular side is much larger
than the others, and is regarded by some morphologists |
as a metatarsal bone. If this be so, the proper tarsalia
are four in number: one each for the first, second, and
third digits, corresponding to the internal, middle, and
external cuneiform bones of human osteology; while
for the fourth and fifth digits there will be a single
tarsal bone, corresponding to the cuboid.

716. Each digit of the foot has a metatarsal bone ; but,
accepting the above view as to the homology of the fifth
bone in the distal row of the tarsus, the fifth metatarsal
is very different in form from the rest. The great toe

DISSECTION OF THE VISCERAL CAVITY. 35

(hallux), has two phalanges ; the second, third, and fourth
toes three each, the terminal bone on each being long
and claw-like. ~The fifth digit has, according to the
homology accepted for the bone on the fibular side of
the distal row of the tarsus, either three or two pha-
langes ; the terminal one, in correspondence with the
absence of a claw on it (5, ¢), is rudimentary.

71. General Dissection of the Pleuro-peritoneal Cavity.
Kill a terrapin with chloroform in the manner above
described (2); saw through the bony bridges uniting
carapace and plastron, and, with scissors, divide the skin
in front and behind, close to the plastron, and then
placing the animal on its dorsum, gradually raise the
plastron from before back. Dissect away, witha scalpel,
the soft parts attached to its inner surface; cut close
to the bone, so as to avoid, as far as possible, all injury
to the soft parts. As you separate the plastron, note
the stout ligaments passing to it from the precoracoids.
When the plastron is removed note the fibrous perios-
teum covering it on its dorsal side, and the attachments
of muscles to it.

78. On the ventral aspect of the animal, as exposed
by removing the plastron, observe :

a. The semi-transparent pericardium, and, seen
through it, the heart, which may still be beat-
ing.

b. Anteriorly, the muscles on the pectoral arch,
and the bones of the latter which can be felt
through them; posteriorly, the pelvic arch,
which can be likewise felt through the muscles
over it.

36

ANATOMY OF A CHELONIAN.

The great pectoral muscle on each side ; flat, and
made up of two portions—an anteen) which
will be seen to have arisen from the plastron
opposite the pectoral arch, and a posterior
larger portion, which arose from the plastron
considerably farther back. Both parts con-
verge to their insertion on one of the tuberos-
ities of the humerus (65).

On the pelvis, a fan-shaped muscle, the origin
of which from the plastron has been divided in
removing the latter; the anterior fibres (attra-
hens pelvis) run backward, the posterior (re-
trahens pelvis) forward, to. be attached to the
large process on the antero-lateral margin of
the pubis. This muscle is the homologue of
the pyramidalis of human myology.

On either side of the pectoral muscles, and
between them, portions of peritoneum are
seen, covered here and there (as is also the
ventral surface of the pericardium) with more
or less yellow fat; in front of the pelvis the
anterior abdominal veins are very conspicuous,
lying on the peritoneum.

79. Dissect away carefully the great pectoral muscles
and the pyramidales, noting the nerves which enter
their deep surfaces. Take care to avoid the branches
entering the anterior abdominal veins in front and be-
hind, and note :

Through the pericardium and peritoneum,
the large quantities of lymph contained in the
cavities they enclose.

On the peritoneum, the two Anterior Abdominal

THE RENI-PORTAL VEIN. 37

Veins, turning dorsally a short distance behind
the heart, and entering the peritoneal cavity.
Joining each, just at this point, is a vein from
the pectoral region, and uniting them in front
of the pelvis, and also behind the heart, are
cross-branches ; that behind the heart will be
seen to receive small pericardiac branches.

c. Posteriorly, note the formation of each an-
terior abdominal vein by the union of a small
branch, running from the ventral aspect of the
pelvis, with a larger vessel appearing at its
outer side ; the former results from the division
of a single larger median vein, which, when
traced back, is seen to be formed by the union
of two lateral trunks with a median one ; these
all carry back some blood from the tail, and
from the ventral regions of the pelvic girdle.

d. Trace back the outer branch. entering into the
anterior abdominal trunk; on the muscles
covering the ilium it is joined by a large vein
from the hind limb ; this, the femoral vein,here
divides into the trunk just described which
enters the anterior abdominal, and- another,
the reni-portal vein, which turns dorsally.

80. If proper care has been taken in the previous dis-
section the veins will be filled with blood and easily
traced ; if they are empty they collapse, and are hard
to follow, and their relative sizes are also impossible to
appreciate. If this be so, cut a hole in one of the
smaller branches ; take a fine blow-pipe, and direct a
current of air on the vessel till it strikes the aperture
and distends it, so that it is readily seen; then put in

38 ANATOMY OF A CHELONIAN.

the tip of the blow-pipe, and inflate the veins with air.
By repeating this procedure from time to time, as re-
quired, the dissection of the venous system is greatly
facilitated.

81. Trace the reni-portal division of the femoral vein
on one side till it penetrates the muscles lying in the
groin-hollow. Then, turning the leg and tail over to
the opposite side, divide the skin between them and the
carapace, and search in the hollow between leg and
thigh for the large caudal vein; trace this up till it
joins the reni-portal.

82. Beginning a short way behind the heart, divide
the peritoneum in the middle line from before back ; a
short distance in front of the pelvis it turns away (oer
the dorsal side, so that the peritoneal cavity does not

extend to the posterior end of the trunk, nor does the ~

peritoneal membrane line the pelvis, being merely re-
flected over the anterior end of the urinary bladder,
which will be seen projecting forward from the pelvic
cavity. ;

83. Remove the ventral portions of the peritoneum
and pericardium, cutting the former away carefully
from around the anterior abdominal veins and the
branches entering them, so as to leave the vessels intact.
Note the J/adder veins, which enter the cross branch’
uniting the two anterior sg ogee trunks near the

pelvis, (79, 2).

84. Putting your thumbs under the coracoid bones,
turn both halves of the pectoral arch forward, tearing
the ligamentous attachment of the scapula to the cara-

asvomrvs RON IS MARSH BALD WP
PRIVATE a be FARY

pace. If necessary, gently run some water among th
viscera to replace the abundant lymph normally pres-
ent and float the organs into their normal positions ;
if the lungs are collapsed inflate them moderately, by
means of a blow-pipe inserted into the glottis ; then
oo the parts as they lie.

aa

85. The following points may be observed before
disturbing the viscera :

a. Anterior to the heart, and disappearing to its
dorsal side, part of the trachea is seen. Note,
that when the neck is retracted it makes a loop
to the left, which is straightened out when the
neck is extended.

b. The heart, with its transversely elongated ven-

- tricle, and right and left auricles; these, together,
almost conceal the venous sinus, which, how-
ever, projects slightly beyond the outer anterior
corner of each auricle. Springing from the
base of the ventricle are several large arteries.

c. On each side of the heart the right and /ef¢

liver lobes, with the gall-bladder appearing from | es
beneath the posterior border of the right lobe. :
d. Partly covered by the left lobe of the liver, o

but seen beyond its edge, is the U-shaped stom-
ach, ending in the pylorus just behind the
heart.

e. The duodenum, starting at the pyloric end of
the stomach, passes to the right, and then
dips away to the dorsal surface. Farther
back are seen some coils of the other portions
of the ztestine, especially on the right side of
the abdominal cavity. |

af

40 ANATOMY OF A CHELONIAN. ~

jf. On each side of the intestinal convolutions
are seen the posterior ends of the lungs.

g. Partly covered by the pubis is the bilobed
urinary bladder, generally much distended. If
collapsed, inflate it by means of a blowpipe
inserted through the cloaca.

h. Immediately posterior to the gall-bladder, a
portion of the pancreas will be seen lying along
the duodenum.

z. Note the entry of each anterior abdominal
vein into the liver-lobe on its own side.

86. Next raise the right liver-lobe, and after observ-
ing the gall-bladder more closely, push the heart up,
and gently separate the left liver-lobe from the stomach ;
the great transverse Portal Vein will then be exposed,
running across the liver from side to side ; opposite
the heart it gets a large vein from the pancreas, and
where it lies against the stomach many small veins
enter it from that organ. Note, also, the bridge of
hepatic tissue uniting the two main liver-lobes across

the middle line, behind the heart ; and the deep fissure ~
on the left lobe into which the right side of the stom-

ach fits, and where many small gastric veins directly
enter the liver.

87. Without cutting the mesentery, gently uncoil the
Small Intestine, and trace it until it joins the Large Intes-

tine; a small Cecum projects beyond the point of com-

munication. Raising the gut, note the Mesentery which
slings it, and in this the numerous arches formed by
branches of the mesenteric artery, from which smaller
twigs pass to the intestine; also the accompanying

mesengpric veins.

ne 2

THE HEART. 4I

88. In connection with the first coil of the intestine,
note the elongated yellowish Pancreas, doubled on it-
self; and, somewhat farther back, lying in the mesentery
near where the small and large intestines join, the
dark-red, soft, rounded Spleen. Near this organ, the
breaking up of the mesenteric artery to form its nu-
merous primary branches will be found, and the union
of the mesenteric veins to form the main radicle of the
portal trunk.

89. Trace the Cystic Duct, which may readily be seen
on squeezing some of the green bile into it from the
bladder, from the gall-bladder to the duodenum. It
opens into the duodenum obliquely after running close
along it for some distance. The Pancreatic Duct opens
into the duodenum about an inch nearer the stomach
than the bile-duct ; it may easily be found on gently
separating the pancreas from the intestine.

90. Trace the Large Intestine to the pelvis ; note the
dilated Rectum, which forms its terminal portion.

91. Examine the Heart more carefully. Its two auri-
cles about equal in size, and the larger ventricle, usually
paralyzed by the chloroform and greatly dilated. Di-
vide the ligament passing from the posterior border of
the ventricle to the pericardium, and raise the former
so as to see the ‘transversely elongated venous sinus
behind it. |

92. Continuous with the right end of the venous
sinus, is the right superior cava. Trace it for about an
inch from the heart, where a small vein will be seen to
enter its posterior side ; make an incision in this and

~ .

€

42 ANATOMY OF A CHELONIAN,.

inflate with a blow-pipe, so as to distend the heart and
vessels connected with it. When the organ is blown
up the relative size and the form of its parts can be
much better seen than was possible previously.

93. Follow now the superior cava on each side, shad-
ing insensibly into the venous sinus, and .formed a
short way from the heart by the union of three large

trunks (118). Entering the posterior border of the

venous sinus, toward the left, is the left hepatic vein; at
the corresponding point on the right side opens a much
larger trunk, formed by the junction within the right
liver-lobe of the inferior cava and the right hepatic vein.

94, Clear away carefully the Zymph sinuses and loose
areolar tissue surrounding the great vessels springing
fi the base of the heart, and carefully clean and
separ te these vessels down to their origin. Extend the

‘neck and remove the skin and connective tissue cover-

=

ingvits ventral surface and sides.

Three vessels spring from the ventricle. That most
to the left is the pulmonary artery; that apparently
next is the left aorta; the remaining one is the right
aorta, which latter is, however, covered close to the
heart by the innominate trunk, which it gives off. On
tracing the aortz carefully to the ventricle it will be
found that the attachment of the left aorta is rather
more to the right than that of its fellow, the two cross-
ing close to the heart.

95. The innominate artery divides almost immediately .
into the right and /eft subclavian, and right and /eft caro-
tid arteries. Dissect these out.

om

THE ARTERIAL SYSTEM. . 43

_ 96. The subclavians lie, at first, ventral to the carotids,
and, diverging, embrace in the angle between them the
. reddish thyroid body; on being traced, each will be
found to give off :

a.

A minute thyroid artery, distributed to the or-
gan of that name.

The ascending cervical, which is distributed on
the ventral surface of the neck and throat.
Farther on, the subclavian passing forward
and outward gives off a short trunk, which
soon divides into branches distributed to mus-
cles about the shoulder and pectoral arch.
Then turning dorsally, the subclavian gives off
the superior cervical, which runs to the side of
the neck near its base, and there breaks up.

vertebral coltmn,-and there passes in between
the first costal plate-and the first rib?
Then it gives off the axillary artery), which,
crossing dorsal to the large cords of the bra-
chial plexus, turns round the sudsc
muscle, and becomes the brachial artery, which
is distributed to the forelimb.

The remainder of the subclavian continues as
the znternal mammary artery, which runs out-
ward to the edge of the carapace, and runs
back along it, in the hollow of the marginal
plate, to anastomose with the epigastric, which
passes forward from the posterior portion of
the dorsal aorta (110, ¢).

Maris

97. The carotid arteries, first dorsal and then external
to the subclavians, cross dorsal to the latter and reach

- Next, a branch, which runs to the side of the e»,

9

4+ ANATOMY OF A CHELONIAN.

their inner aa they then run along the neck to the
head. About half way up the neck they come into re-
lation with the sympathetic and pneumogastric nerves, and
the internal jugular vein. Trace each carotid, taking
great care of the nerves near its upper end, until it en-
ters the skull by a foramen (26, e), just in front of the
auditory capsule.

98. As each carotid is dissected, the thymus gland
will be found—a loosely aggregated, yellowish mass,
near the base of the neck on each side, and internal to
the artery.

99. It will be best to trace back the pneumogastric
nerves now, as their terminal branches are apt to be
injured in dissecting the aortic arches. Just behind the
' hyoidean apparatus, the carotid artery has the vagus on
its outer, and the cervical sympathetic on its inner side.
For the present follow the nerves from the skull, be-
ginning about an inch and a half behind the cranium.
A short way from the head, the sympathetic comes into
close relation with the vagus, so that care is needed to
separate them ; finally, about opposite the fifth cervical
vertebra, the nerves separate, the sympathetic passing
out toward the axilla.

100. Follow the left pneumogastric till it crosses the
left aorta; at this point it gives off the recurrent laryn-
geal nerve, which, turning round the aorta, runs up the
neck alongside the gullet. After giving off this branch,
the vagus stem breaks up into a leash of branches, some
of which run mesially toward the heart, while others
may readily be traced along the bronchus to the lung,
and to the ventral side of the stomach near the cardia.

THE ARTERIAL SYSTEM. 45

101. The right pneumogastric has a similar distribu-
tion ; its terminal gastric branches are very long, and
cross behind the heart to the dorsal side of the stomach.

102. Divide the fibrous bands which pass between
the right lung and the right lobe of the liver, taking
great care not to prick the lung. Next push the right
liver-lobe over to the left side, and carefully separate
the lung from the muscles lying on the vertebral col-
umn. Then trace the right aorta; it will be seen to
arch over the pulmonary vessels and the right bron-
chus, and to receive a communicating branch from the left
aorta, near the dorsal side of the visceral cavity and
opposite the fourth dorsal vertebra. From the point of
union, the dorsal aorta will be seen passing backward.

103, Carefully divide, on the left side, the connective
tissue uniting the lung to the cardiac end of the
stomach, and the lung to the muscles on the dorsal ver-
tebrae, and trace the left aorta. Passing round the left
bronchus and pulmonary vessels to the dorsal side, it
ends by dividing into three main trunks, which are to
be traced successively by spreading out the mesentery
and pushing aside the viscera.

104. The external division of the left aorta gives off :
a. The gastric artery, which runs a short way on
the dorsal aspect of the stomach and then bi-
furcates to form the right gastro-epiploic artery,
which runs along the great curvature of the
stomach ; and the coronary artery of the stomach,
which runs along the small curvature of that
organ.

46 ANATOMY OF A CHELONIAN.

db. The remainder of this division runs on as the
communicating artery to join the right aorta,

105. The middle division is the superior mesenteric; it
breaks up in the mesentery (87) to supply most of the
gut, and also gives a branch to the spleen.

106. The third division (the gastro-duodenal artery) di-
vides into two main stems, the superior and inferior pan-
creatico-duodenal arteries, the former running to the left,
and the latter to the right end of the pancreas. Each
then courses between duodenum and pancreas to anas-
tomose with the other, giving off branches to the gut
and gland on the way.

The superior pancreatico-duodenal gives off a branch, the
left gastro-epiploic artery, which runs along the great cur-
vature of the-stomach, and inosculates with the right
gastro-epiploic. .

107. Now divide the intestine close to the stomach,
and again in its rectal portion about two inches in
front of the pelvis. Remove the portion of the gut be-
tween the two incisions by cutting through the mesen-
tery close to it; while so doing note the large fold,
with its concavity to the left, made by the co/ox as it pro-
ceeds from the junction with the small intestine, and
before turning directly back to the cloaca as the rectum.

108. Spread out the removed portion of the gut;
note that the small intestine is from five to six times
longer than the carapace, and the large about one-fourth
the length of the small. Then open the small intestine
along its whole length, and note its thick muscular coat

THE ARTERIAL SYSTEM. 47

and the longitudinal folding of its mucous membrane.
Pass bristles in from the pancreatic and cystic ducts,
and observe that each passes obliquely through the in-
testinal wall.

109. Open the coecum and colon along their free
borders; note the absence of an ileo-colic valve, and
the: muscular and mucous coats of the tube.

110. The dorsal aorta may now be followed back from
its point of formation (102). Passing between the kid-
neys, it ends behind them by dividing into the v7ght and
the eft common iliacs. In dissecting its branches, which
is a matter of some difficulty, disturb the renal and re-
productive organs as little as possible. With care the
following branches will be found :

a. Several small twigs to the kidneys and genital
glands.

6. A pair of branches which run dorsally, and
enter the canal on each side of the vertebral
column, which is arched over by the necks of
the ribs.

c. A branch (efigastricartery) on each side, which
runs out dorsal to the kidney ; and, reaching the
edge of the carapace, runs forward to anasto-
mose with the internal mammary (96, g).

d. Abranch on each side, distributed to the pelvic
muscles.

111. Each of the common iliac arteries, the terminal
branches of the dorsal aorta, soon divides into an infer-
nal and an external iliac.

112. The left internal iliac almost immediately gives

48 ANATOMY OF A CHELONIAN.

off a large branch (nferior mesenteric) to the colon, and
the right a much smaller twig to the rectum ; the trunks
then proceed to the pelvis and are distributed to the
penis or clitoris. |

118. Each external iliac passes outward and back-
ward, and divides into—

a. A branch distributed to the muscles of the
pelvis and the inner aspect of the thigh.

b. The sciatic artery, which supplies most of the
lower limb. It takes a more dorsal direction
than a, and approaches the carapace in the
region of the sacral vertebre, there coming
into relation with the sczatic nerve. Giving off
in this region a small branch, the artery turns
outward with the nerve, and the two (passing
on the mesial side of the ilium) reach the back
of the leg, where they may be found and traced
in their further distribution by dividing the
skin and subcutaneous tisste along a line
drawn from the inner side of the dorsal end
of the ilium to the outer side of the knee-joint.

114. Clean and trace the pulmonary artery; immedi-
ately after springing from the ventricle it. divides into
a right and left branch. The right passes dorsally to all
the other trunks proceeding from the ventricle on the
right side of the heart, and is found lying posterior to,
and parallel with, the right aorta for some distance ;
it then crosses ventrally to this vessel and enters the
lung. The left pulmonary artery runs forward and
outward to its lung.

115. Trace the pulmonary veins, one from each lung,

THE SUPERIOR CAVA. 49

near which organ the vessels lie alongside the bronchus
and pulmonary artery ; these veins open into the left
auricle.

~ 16. Note the small coronary arteries and veins lying
on the surface of the ventricle. The arteries spring
from the innominate trunk, and the veins enter the
venous sinus.

117. Trace out the system of the two superior cave;
as a preparatory step, remove the skin from the dorsal
side of the neck and inflate the vessels from some one
of their smaller branches. This inflation will need to
be repeated from time to time as the dissection pro-
ceeds, as many of the branches when empty are very
hard to follow.

118. The superior cava, shading insensibly into the
venous sinus at one end, is composed at its other, a
short way from the heart, by the junction of three
considerable trunks. Dissect them out on the left side.

a The inner division (internal jugular) runs up
the side of the neck, where it is found accom-
panying the carotid artery and vagus nerve.

6. The middle and largest division (subclavian)
may be traced to the forelimb. Near the base
of the neck it receives a cervical branch (ex-
ternal jugular) which is to be followed up the
neck to the neighborhood of the occiput,
where it is formed by the union of a branch
(facial vein) from the mandibular region with
a cross branch, which may be followed across
the middle line by dividing some muscles pass-

3

50' ANATOMY OF A CHELONIAN.

ing from the occiput to the cervical vertebra,
and beneath which it passes to join its fellow.
Into this cross branch opens, on each side, a
vein from the exterior of the cranium, and
also one from inside the skull cavity.

¢. Beyond the point where the subclavian vein
receives the external jugular, it gets a branch
from the regions near the base of the neck on
the dorsal aspect; it then continues to the
forelimb.

119. The outer division of the superior cava crosses
over the armpit, receiving some branches in that region,
and then runs, as the internal mammary, along the mar-
gin of the carapace with the artery of that name (96, g).

120. Before proceeding to study the inferior vena
cava, it will be necessary to dissect the Genito-urinary
Apparatus, Endeavor to get your next specimen (193)
of the other sex,* and on it complete the examination
of the reproductive organs.

121. If your present specimen be a female, proceed
next to section 138; if it be a male,-examine the
Male Reproductive Organs; for this purpose divide the
pelvic bones along the median ventral line and push
the halves apart; then divide. the muscles beneath.

*It is not easy to tell the sex of a Slider from external exam-
ination ; dealers profess to tell by a supposed greater convexity of the
posterior part of the carapace in the female. But we have not found
this reliable. When a number of students are working together in a
laboratory, they will, however, be able to arrange it between them so that
all shall get a specimen of each sex,

MALE REPRODUCTIVE ORGANS, 51

Clean carefully the ventral wall of the thin cloaca, back
to its external aperture ; meeting on it in the median
line will be found a pair of thin, rounded muscles, ve-
tractors of the penis, which pass at first backward, and
then, turning around another muscle, forward and dor-
sally to their origin. Through the ventral wall of the
cloaca the large, dark-colored fens. will be seen. e

122. Pass a pair of forceps through the opening of
the extremely distensible cloaca, and dilate the latter
by spreading the prongs of the forceps apart. Note
the penis attached for some way along the ventral side
of the cloaca, terminating posteriorly in a free enlarge-
ment (g/azs), and having a deep groove along its dorsal
surface.

123. Slit the cloaca open along one side, taking care
not to injure the penis, and examine the latter; it is
composed of two elongated corpora cavernosa placed
side by side, and in contact in the median line. Each
corpus cavernosum, narrowing as it runs forward, ends
anteriorly in a highly vascular dilatation or du/b. This
is best seen through the ventral side of the cloaca.

124, Make a small hole in a vein which leaves the
bulb upon its ventral and outer side ; insert the end of
a blow-pipe and inflate the penis ; note its extreme dis-
tensibility, and how it becomes erect when distended.
The corpora cavernosa at the same time swell up and
press against each other, converting the groove on the
dorsum of the penis into a canal. Observe, also, the
great distention of the glans, and the elevated lips bound-
ing the end of the urethral groove on it; also, the cur--

52 ANATOMY OF A CHELONIAN.

vature of the erected organ (owing to the greater elas-
ticity ofthe tissues upon its dorsal side), which causes
it to bend forward and ventrally.

125. Raise the urinary bladder, and observe that it
ends in a narrow zeck, which is attached to the front end
ef the cloaca; make a hole in it and pass a probe from
its cavity into the cloaca; pass another probe into the
cloaca from the cut end of the rectum (107).

126. Bend the penis forward and fix it; wash the
mucus away from inside the cloaca, and find where
the probes have entered the latter. That from the
bladder appears through an opening at. the end of the
urethral groove ; the rectal opening is dorsal to this.

127. Dorsal and a little to one side of the bladder,
opening on each side, are the large apertures of the
accessory bladders.

128. Replace the penis, turn the bladder back, and
fix it in position. Wash out the abdominal cavity with
a stream of water, and, filling the carapace with clean
_ water, examine the reproductive glands.

129. The testes, a pair of rounded yellow bodies, are
placed a short way in front of the pelvis. Each has on
it a darkly pigmented, convoluted mass, the epididymis,
which extends back beyond it.

180. Turning the testes and epididymis toward the
middle line, seek a long tube thrown into curves and
ending anteriorly in a small dilatation placed dorsal to

MALE REPRODUCTIVE ORGANS. Rae

the posterior end of the lung ; posteriorly this tube nar-
rows greatly, but it may be traced along the dorsal side
of the epididymis to near the cloaca, where it ends
blindly. It appears to be the unaborted Millerian duct
of the embryo, and therefore homologous with the ovi-
duct of the female.

131. In the cloaca, a short way external and posterior
to the proximal end of the urethral groove, seek the
small slit-like aperture of each vas deferens.. On intro-
ducing a probe from the cloaca, the duct may be traced
for a considerable distance along the ventral border of
the testis.

132. Raise the testicle so as to stretch the band of
peritoneum between it and the epididymis. In this
band will be seen anumber of small vasa efferentia pass-
ing from the testis to the epididymis. Then dissect
away the peritoneum covering the epididymis, and ob-
serve that the latter organ is made of a much-coiled
tube, with its folds bound together by pigmented con-
nective tissue.

133. Turn the left testis and epididymis to the middle
line, and push the posterior end of the lung out of the
way. The outer half and the anterior end of the ven-
tral surface of the red kidney will then come into view ;
and, running along it from before back, close to the
point where the connective tissue binding it to the epi-
didymis is attached, a large vein will be seen. Care-
fully trace the branches which enter this; they are:

a. From behind, a trunk from the penis, through
which the whole set may be conveniently in-
flated.

54 ANATOMY OF A CHELONIAN. |

6. Entering through a fissure on the outer edge
of the kidney, between two of its lobes, the
reni-portal vein. Trace this back through the
muscles of the groin-hollow to the point up to
which it has already been dissected (81). ”

ce. A branch entering through another fissure,
placed farther forward on the outer margin of
the kidney. This vein comes from the lateral
regions of the posterior part of the carapace.

@. Farther forward, and in still another fissure, a
vein which proceeds from the passage along-
side the vertebral centra, which is arched over
by the necks of the ribs.

134. Now, replacing the testis and epididymis, find
the posterior vena cava, lying onthe muscles in front of
the vertebral column and beside the dorsal aorta. Fol-
low it forward until it enters the right lobe of the hver,
and then, cutting away the hepatic tissue, trace itup to
_ the venous sinus, receiving the right hepatic veins on its
way, and also the right anterior abdominal vein.

135. Next trace the vein back, turning aside the re-
productive organs where they come in the way and also
tearing through the bands of peritoneum slinging them,
The vessel will be seen to commencewpposite the kid-
neys by the union of several renal veins, with branches
from the testes and epididymes.

136. Cut away the left testis and epididymis, and
clean the ventral surface of the kidney of the same side.
The gland will be seen to be lobulated, and to present
externally the appearance of being made up of a greatly

FEMALE REPRODUCTIVE ORGANS. 55

convoluted tube. From its ventral surface several
ducts pass out, and unite to form the wreter. Trace this
duct to the cloaca, and find its aperture in the latter.
It lies at the proximal end of the urethral groove, out-
side, but close to the aperture of the bladder.

137. Note the bright yellow adrenal body lying along
the mesial border of the kidney.

138. If your specimen be a male, now pass on to sec-
tion 143. If it be afemale, proceed to study the Repro-
ductive Organs of the Female. Remove the ventral side
of the pelvis, as directed in section 121. Note the
slender homologues of the retractors of the penis, and
also the clitoris, much resembling a miniature penis.
Then open the cloaca on one side (123) and study the
clitoris more clearly ; observe the urethral groove between
its two small corpora cavernosa, and the relatively large
glans clitoridis in which it ends.

139. Examine the urinary and accessory bladders
(125, 126, 127), which resemble those of the male.

140. Examine the ovaries: granular-looking orange-
red masses, with ova of varying maturity and very dif-
ferent sizes in them.

141. Find the oviduct. It is a slightly convoluted
tube lying in a broad fold of peritoneum, and opening
by.a wide mouth into the peritoneal cavity dorsal to
the posterior end of thelung. Follow it tothe cloaca,
where its walls are thicker than elsewhere. Then, on
the interior of the cloaca seek two small papilla, one

56 ANATOMY OF A CHELONIAN.

on either side of the bladder aperture; on these the
oviducts open ; pass a probe through one. If the ovi-
duct contains no ova it is often hard to find; in that
case inflate it from its cloacal termination.

142. Next make the dissections described in sections
133-137 inclusive ; reading, where necessary, ‘‘ ovary,”
for ‘‘testis and epididymis.”

143. Remove the heart very carefully, dividing the
vessels at some distance from it where practicable.
Place it on wax in a shallow dish containing dilute
alcohol; fix it (by pins passed through the vessels) in
-various positions as may be most convenient, and
carefully make out the points at which, as viewed from
the exterior, various Sessels enter and leave it (94).

144, Next cut away cautiously the ventral side of
the ventricle, and note the incomplete septum attached
to this wall and partially cutting off a small right por-
tion (cavum pulmonale) from a larger left division of the
ventricular cavity. Projecting into the left division is
the posterior free end of the auricular septum, which
thus incompletely divides the left portion of the ven-
tricle into a right half (cavum venosum) which gets blood
from the right auricle, and a left (cavum arteriosum)
which receives blood from the left auricle.

145. Open the pulmonary artery and pass a bristle,
guarded at the end with a small knob of sealing-wax,
along it to the heart. Though the furthest Ze/¢ of the
vessels springing from the ventricle when the heart is
viewed from outside, the pulmonary artery will be

THE RESPIRATORY ORGANS. 57

found to open into the furthest right subdivision of the
ventricle—the cavum pulmonale. Pass bristles similarly
along the aortz ; both will be found to open into the
median division of the ventricle—the cavum venosum ;
the opening of the left aorta being to the right of that
of the right aorta. Slit open the arteries, and observe
the valves at their mouths.

146. Observe the Trachea; note the way it is curved
when the neck is retracted, and its division on the right
side of the retracted neck into the right and /eft bron-
chus, each of which enters its own lung near the ante-
rior end, alongside the pulmonary artery and vein.

147. Remove the hyoidean apparatus, with the
tongue, larynx, and a bit of the trachea attached. To
do this, divide the muscles, etc., between the rami of
the lower jaw and the anterior horns of the hyoid, so as
to open the buccal cavity from its floor; then seize the
tongue with forceps and draw it out; note the stylo-
hyoid ligament passing from the anterior horn of the
hyoid to the base of the skull. Divide it on each side ;
cut through the trachea about an inch behind the lar-
ynx, also any other connecting bands, and remove the
mass. Note the eminence at the back of the tongue
(4, c), and the slit (aditus laryngis) in it which leads into
the larynx. Separate the firm edges of the slit, and
examine the interior of the /arynx, wiping out mucus,
etc., with a little bit of sponge held by a small pair of
forceps.

148. Put the removed parts away to macerate in
water for a few days; then separate and examine the
3*

58

ANATOMY OF A CHELONIAN.

Larynx and Hyoidean Apparatus; the description of the
latter has already been given (57).

a.

The framework of the larynx is composed of

three cartilages: a posterior large, circular

‘piece (crico-thyroid), anda pair of smaller (ary-

tenoid) articulated with its anterior margin.
The crico-thyroid cartilage fits closely into the
concavity at the back of the body of the hyoid,
and is thin and membranous in the middle of
its convex anterior surface. The arytenoids
bound the sides of the aperture (aditus laryn-

gis) which lies at the base of the tongue (4, ¢).

149. Inflate the lungs fully from the cut end of the
windpipe, and then ligature the latter to prevent the
escape of the air. Note:

a,

The position of the Lungs, on either side of the
vertebral column, in the hollow of the cara-'
pace.

The layer of pleuro-peritoneum, which covers
them and bends them down to the bones pretty
closely in front, but leaves their posterior ends ~
free. .
Through the serous membrane, a thm muscu-
lar stratum (diaphragm) may be seen, forming
a sheet all over the lung, but thicker in front
than behind and dorsally than ventrally.
Pushing one lung aside, divide the diaphragm
close to the vertebral column, and dissect out
the organ. As the lung is removed, its en-

. veloping muscle will be seen to arise from the

necks of some of the ribs, from the vertebral

TEE LONG S. 59

centra between them, and from a small neigh-
boring area of the costal plates. From these
attachments the fibres spread out on all sides
to invest the lung.

150. Cut through the bronchus, and entirely remove
the lung.. Inflate it from the bronchus, and keep it
distended by tying the latter; then hang it up for a
day or two to dry. When dry divide it into a dorsal
and ventral half, and observe its internal structure.
Note:
a. Thatthe bronchus is continued by a large tube
rupning to the posterior end of the lung, but
having no cartilages in its walls, except fora
very short distance near its commencement.

6. That from this main bronchial tube, others di-
verge at right angles to its general direction,
and end in incompletely separated air-cells,
which are much smaller in the anterior than
in the posterior portion of the lung.

151. Trace the Esophagus up to the mouth, and, pass-
ing a probe down from the latter, note the great disten-
sibility of the upper part of the gullet. Then remove
stomach and cesophagus, and, opening them, note the
folded mucous membrane lining them ; the rug@ being
most conspicuous in the stomach.

152. Remove carefully the remaining lung, the liver,
and the genito-urinary organs, taking care not to -in-
jure the dorsal spinal nerves, which are seen running
out across the interior of the carapace ; then clean the
great Retractor Muscles of the Head and Neck, of which

60 ANATOMY OF A CHELONIAN.

there are four on each side. Posteriorly they arise
without distinct tendons, from the bodies of the dorsal
vertebrz from the fourth to the eighth, the one which
extends farthest forward having its origin farthest back.
This, the longest of the muscles, ends in front by a
tendon which is inserted on the posterior part of the
skull; the next is inserted on the ventral surface of the
anterior outer angle of the centrum of the fifth cervical
vertebra ; the remaining muscles are similarly fixed to
the sixth and seventh cervical vertebra respectively.

The Protractors of the Head and Neck, which run from
the carapace and pectoral arch to the neck, may now
also be noted.

153. Cut away the retractor muscles ; also the ventral
three-fourths of the ilium on the side where the sciatic
nerve has already been seen (113, 4), and trace the
nerve down the limb, and also up to its formation by
the union of four trunks (sciatic plexus) which appear
through the inter-vertebral foramen between the last
dorsal and first sacral vertebrze and the three succeed-
ing foramina. The second of these trunks is the largest ;
the fourth the smallest. This plexus also communi-:
cates with the lumbar plexus (154) by a small branch, ©
and gives some small twigs to the pelvis.

154. The nerve-trunks which appear through the two
foramina on each side which are next in front of those
through which the roots of the sciatic plexus pass out,
unite to form the lumbar plexus, offshoots of which may
be traced to the inner aspect of the thigh. .

155. Clear away the muscles, etc., on the anterior

THE SPINAI. NERVES. 61

part of the tail, and note the small caudal spinal nerves
as they appear through their foramina of exit.

156. Running out across the carapace, note the main
branches of the dorsal spinal nerves, from the second
(which appears between the second and third dorsal
vertebrze) to the seventh, inclusive. Each consists of
two main divisions which lie side by side.

157. The first dorsal nerve gives off, close to the ver-
tebral column, a branch which enters the brachial
plexus (159), and then runs out dorsal to the shoulder-
girdle. Parallel to the communicating branch to the
brachial plexus, and close to it, is a branch of the main
sympathetic chain, which may be noted asa guide in
the subsequent dissection of the sympathetic system.

158. There are nine cervical spinal nerves, which, ex-
cept the first, may be found on clearing away the mus-
cles on the sides of the neck. The first (sub-occipital
nerve) is very small and has no posterior root. To find
it flex the head on the spine, open the membrane be-
tween occiput and atlas, and with bone forceps cut
away the dorsal half of the latter bone. On then gently
raising the exposed part of the spinal cord and pushing
it to one side, the first cervical nerve will be seen run-
ning out between the occipital bone and the atlas. Do
not confound it with the-spinal accessory (180, %), or
hypoglossal (180, 2), which can also be seen; the former
runs on into the cranial cavity; the latter passes out

through a foramen in the exoccipital bone.
Co

159. The seventh, eighth, ninth, and tenth cervical
spinal nerves form the brachial plexus, which also gets

<J

62 ANATOMY OF A CHELONIAN.

a branch (157) from the first dorsal nerve. Trace the
trunks springing from the plexus to their distribution
in the fore limbs.

160. Clear away the muscles still attached to the
spinal column in the carapace region and remove what
remains of the pelvis, taking care to leave the sacral
ribs. Note that the sacrum has a considerable amount
of mobility from side to side, the enlarged outer end of
the first sacral rib gliding over a smooth elevation on
the carapace (15). Such movements, when the parts:
are in their natural connections, would carry the pelvis
with them, so that the pelvic arch is less rigidly fixed
than in most vertebrates. Next, remove the pectoral
girdle, noting the stout ligament which fixes the dorsal
end of each scapula to the carapace.

161. Cut away the centra of all the vertebrz sufficiently
to open the neural canal and expose the ventral surface
of the dura mater. Then slit open this membrane along
the middle line, and reflect.it to each side, so as to ex-
pose the spinal cord; take great care not to injure the
roots of the spinal nerves. Note the considerable space
between the cord and the dura mater.

162. The spinal cord, in its course, will be seen to
present two considerable exlargements. The anterior, or
cervical, extends from the front of the sixth cervical to
the back of the first dorsal vertebra, and gives origin to
the roots which enter the brachial plexus. The fos-
terior, or lumbar enlargement, extends from the ninth
dorsal to the first caudal vertebra inclusive, and gives
origin to the trunks of the sciatic plexus.

THE SPINAL CORD. 63

The cord is comparatively very slender in the region
between the two enlargements, and, in the tail region,
gradually tapers off ; but it extends to the end of the
vertebral column, there being no cauda eguina ; along its
ventral aspect the cord presents a well-marked median
anterior fissure.

S

163. Carefully raise a bit of the cord in the region of
the lumbar enlargement ; note that the spinal trunks
are formed by the union, outside the neural canal, of
a ventral (anterior) and dorsal ( posterior) root, and that
each root in turg arises from the cord by a number of
small separate bundles. To see the roots well a hand-
lens will be found of use.

164. Examine the roots in the middle dorsal region,
and in the neck. In the former they are very small.

165. Carefully frace a pair of roots in the middle
dorsal region. They will be found to reach a compara-
tively large spinal ganglion which lies, imbedded in pig-
mented connective tissue, in one of the hollows found
along the vertebral column, between the necks of the
ribs. From the outer side of the ganglion proceed the
two trunks already referred to (156); they are con-
siderably larger than the roots entering the ganglion.

Next trace out some roots in the anterior cervical
region and the cervical and lumbar enlargements, and
note the ganglia attached to them.

166. Cutting away the bone more freely, remove
parts of the spinal cord, and make sections of it at
different levels. Note the well-marked anterior jissure ;

64 ANATOMY OF A CHELONIAN.

the conspicuous gray matter in the centre in relatively
small amount, but with well-marked cornua and a dis-
tinct gray commissure.

On the dorsal aspect of the cord, note the shallow
groove indicating the posterior fissure, and the furrow
on each side of it along which the posterior roots are
attached. .

167. Now proceed to the Dissection of the Brain and
Cranial Nerves and the Sense Organs connected with them.
With a jeweller’s saw cut through the soft parts and
cranium in a plane parallel to the median antero-pos-
terior vertical plane of the head, and passing in front
through the outer margin of the right nostril; carry
your incision from above down through the base of the
skull, but leave the mandible undivided. The skull
will thus be divided into a larger left and a smaller
right segment, the former containing the brain, which
is exposed on its right side by the section.

163. On the cut surface of the left portion, beginning
in front, note:

a. The nasal chamber, lined by brown mucous
membrane, which is folded near the opening
of the anterior nostril. |

&, Separated from the nasal cavity by a thin plate
of bone is a small part of the median portion
of the right orbito-temporal fossa, with a bit of
the Harderian gland (which has been divided by
the saw) lying in it anteriorly.

c. Aboye and internal to this will be found part
of the superior oblique muscle.

ad. Close to the membranous upper and posterior

a

THE BRAIN. | 65

boundary of the part of the fossa now under
examination, will be found two nerves: the
orbito-nasal or ophthalmic, a branch of the fifth
cranial, and the patheticus (fourth cranial) ; the
former is the larger. —

e. Gently removing the bit of Harderian gland, ob-
serve the membranous ixter-orbital septum, and
trace the orbito-nasal nerve forward along it
until it enters the nasal chamber. The origin
of the superior oblique muscle is above this
point of exit, and the fourth nerve may be
traced into the muscle near to its origin.

169. Lying above the inter-orbital septum is a pro-
longation of the cranial cavity covered in by dura
mater, aa oofed argee bore.” ‘On cutting away the
bone sir d wareriod the side, the whole
of ee PIA the ae will be exposed if the
original cut were made in the proper plane, passing be-
hind through the right margin of the foramen magnum.
If the cut has taken a too external direction behind,

carefully break the bone away from time to time as may
be necessary to observe the parts described below.

170. On the side of the brain, note:

a. The right olfactory lobe, reaching in front to the
posterior boundary of the nostril and marked
off behind by a shallow furrow from—

b, The right cerebral hemisphere, which is separa-
ted behind by a deeper furrow from—

c. The mid-brain or mesencephalon, behind which
comes—

_ a, The cerebellum.

66 ANATOMY OF A CHELONIAN.

eé. Ventral to the cerebellum, and reaching an-
teriorly to the mid-brain, is the medulla oblon-
gata or myeloncephalon, which is seen to be
continuous posteriorly with the spinal cord or
myelon.

jf. The medulla and the ventral parts of the mid-
brain are white; the other portions of the
brain now exposed are gray.

171. Carefully raise the cerebral hemisphere so as to
expose beneath its posterior portion the ¢halamencepha-
fon, and under this note the large, white optic tract
running forward from the mid-brain to join its fellow in
the optic chiasma ; from the latter, trace the right offic
nerve forward to the point where it has been divided. It
will be seen to turn out into the orbital fossa, just be-
hind the inter-orbital septum ; and, as soon as it enters
the fossa, to cross out beneath the ophthalmic nerve,
which runs between it and the superior rectus muscle
near the origin of the latter.

172. About the point where cerebellum, medulla ob-
longata, and mid-brain meet, the posterior end of the
small fourth nerve will be seen ; trace it forward. Next,
gently raise the mid-brain from the base of the skull,
and note the ¢hird cranial nerve (motor oculi) ranning from
it to the orbit, which it enters somewhat posterior and
external to the optic trunk.

173. On the small right hand portion of the skull

(167) will be seen:
a. A much larger portion of the nasal chamber
than that which was found on the left section.

THE CRANIAL NERVES. 67

6. Behind this the main portion of the right or-
bital fossa, containing the eyeball and most of
its muscles, and the outer part of the optic
nerve attached to the globe. Entering the
orbit behind and running forward near its roof
will be seen a slender branch of the third
nerve.

174. Behind the orbit is a thin plate of the parietal
bone (45), separating the cranial cavity from the tempo-
ral fossa. On its inner side will be found the sixth
nerve, running forward to the orbit, through which
cavity it may be traced to the external rectus muscle.
On the inner surface of the bone is also a fossa, or de-
pression, opposite the back part of the cerebral hemi-
sphere and the front of the mid-brain, and placed be-
tween the parietal and prodtic bones. Pull away the
dura mater which covers this pit, and the large Gasserian
ganglion will be exposed, with the sensory root of the
fifth cranial nerve entering it. Proceeding forward
from the ganglion, will be found the stump of the orbito-
nasal nerve, the peripheral part of which has already
been seen (168, @).

175. Posterior to the fifth nerve, the seventh of the
right side will be seen, entering a foramen in the cranial
wall; and, close behind it, the smaller e¢ghth (auditory)
nerve, entering the auditory capsule. Above its point
of entry the inner wall of the labyrinth is cartilaginous.

176. Still farther back is the foramen of exit for the
tenth and eleventh nerves (pueumogastric and spinal ac-
CeSSOrY).

68

ANATOMY OF A CHELONIAN.

177. On the right portion of the divided head, the Ear
is to be dissected either now or after completing the
dissections described in paragraphs 179-192, inclusive.
For this purpose—

a.

Remove the skin over the tympanum (3, /) ;
note the white, opaque, fibrous ring surround-
ing the aperture, and the circular cartilaginous
plate which nearly fills it up, and is united to ~
its margin by a delicate membrane.

Cut away the uniting membrane, and turn
the cartilage (which is the outer expansion of
the columella, 26, 7) to one side; the rod-like
portion of the columella will’be seen running
in from it. Cut off the outer end of the col-
umella, and examine again the outer division
of the tympanum (27, 2) now lined by mucous
membrane; the columella traverses it and
disappears on its inner side through a narrow
passage. Beneath and behind the columella
is a slit bounded by a pair of white prominent
lips ; this is the tympanic opening of the Zus-
tachian tube; pass a guarded bristle along it
to its oral end, which will be found to open
on the side of the buccal cavity, just behind
the prominence caused by the powerful mus-
cles which run from the temporal fossa to the
mandible.

Carefully break away the floor of the tym-
panum, and trace the columella through its
fibrous canal to the inner dilatation of the tym-
panum (26, 2), where it ends in a circular car-
tilaginous plate, smaller than the outer one,
fixed in the foramen ovale.

THE INTERNAL EAR. 69

178. Break away the base of the skull internal to the
tympanum, so as to open the vestibule, which, if the
saw was held in the proper plane while dividing the
skull, will not have been injured. The vestibule has
three semicircular canals opening into it, and in front
is aconical prolongation of its cavity, which represents
a rudimentary cochlea.

a.

The semicircular canals are not very easy to
trace on a fresh specimen. If they are not
recognized, take first a dried macerated skull,
and open the vestibule from its base ; clear
away the membrane lining it, and note the
recesses of its wall: an anterior at the base
of the cochlea, a superior, and a posterior ;
into these semicircular canals open. The

anterior and posterior vertical canals open into

the upper recess by their non-ampullary ends ;
a fine bristle pushed forward from this recess
passes on through the anterior vertical canal
and appears again, through its ampullary en-
largement, in the anterior recess. From the
posterior recess the posterior vertical and hort-
zontal canals proceed ; the former here has its
ampulla, and through it a bristle may be passed
to the superior recess. Push another bristle
forward from the opening of the horizontal
canal; it will reappear in the anterior recess,
where the ampulla of this canal opens.
Having now found the position of the open-
ings, trace out the canals on your fresh speci-
men.

179. Returning to the left side of your section of the

7O

ANATOMY OF A CHELONIAN.

head, break away the bone on the roof of the skull, tak-
ing care not to injure the auditory capsule, and note
from before back, on the dorsal aspect of the brain :

. a.
b.

The olfactory lobes.

The cerebral hemispheres, or prosencephalic
lobes, with the pineal gland lying in the angle
where they diverge behind.

The corpora bigemina, forming the dorsal part
of the mid-brain.

The unpaired cerebellum ; and, behind it—
The medulla oblongata, covered by a highly vas-
cular plug of pia mater, forming a choroid
plexus. On removing this, the fourth cerebral
ventricle will be partly exposed on the dorsal
aspect of the medulla. Raise the posterior
free border of the cerebellum, and note that
the fourth ventricle is continued forward be-
neath it.

180. Carefully tilt the brain over toward the right,
and study the origin of the various Cranial Nerves on
the left side.

a.

The olfactory (first cranial nerve), proceeding
from the end of the olfactory lobes.

The optic or second cranial nerve (171).

The third nerve (oculo-motor) arising from the
ventral aspect (crus cerebri) of the mid-brain.
The fourth nerve (patheticus) will be first found
on the dorsal side of the crus cerebri, close
to the cerebellum ; thence it passes forward and
downward till it reaches the base of the skull, ~
on which it runs forward parallel and exter-
nal to the third nerve. The three preceding

h.

THE CRANIAL NERVES. 71

nerves all disappear through the dura mater
closing in the skull cavity in front, and sep-
arating it from the orbital cavity.

Carefully separate the soft parts beneath from
the bony roof of the temporal fossa and orbit,
and chip away the bone. Note the large ji/th
nerve (trigeminal) arising from the anterior part
of the side of the medulla, and passing through
the dura mater; also the Gassertan ganglion
(174), which may be exposed by removing the
membrane over it.

Posterior to the fifth nerve, the seventh (facta?)
and eighth (auditory) rise together from the side
of the medulla; they soon diverge and pass
out by separate foramina, that of the seventh

being anterior to the cartilaginous inner side

of the labyrinth.

The glosso-pharyngeal nerve (ninth cranial) arises
from the medulla, and leaves the skull by a
foramen in the opisthotic bone immediately
behind the cartilaginous portion of the inner
wall of the labyrinth.

Immediately behind the glosso-pharyngeal a
number of nerve-roots arise. from the side of
the medulla; the anterior unite to form the
tenth nerve (pueumogastric) ; the posterior (re-
inforced by filaments from the anterior end of
the spinal cord) form the eleventh nerve, or
spinal accessory. The two leave the skull bya
large common foramen, between the exocci-
pital and opisthotic bones.

The sixth and twelfth cranial nerves ( abducens
and hypoglossal respectively) have foramina of

72 ANATOMY OF A CHELONIAN.

exit nearer the median line than any of the
above, so that the brain must be turned farther
over in order to see them. The sixth arises
from the ventral aspect of the medulla near its
anterior end, and, after a short course, enters a
canal in the basisphenoid bone; farther for-
ward it reappears in the cranial cavity beneath
the anterior clinoid process and passes on to
the region where it has been already described
(174). The twelfth nerve arises from the ventral
aspect of the medulla near its posterior end,
and passes out through one of the condyloid
foramina.

181. Remove the brain (dividing the nerves close to
their origins with sharp scissors) and place it aside in
alcohol for future examination; then trace out the
branches proceeding from the left Gasserian ganglion.
On cleaning away the dura mater, which covers the
inner surface of the descending plate of the parietal
bone and of the alisphenoid, the ophthalmic branch of the
fifth nerve will be found. ‘Trace it forward to the orbit ;
it enters this a little external and posterior to the optic
nerve, which will be recognized passing in beneath the
superior rectus muscle. In the orbit the ophthalmic
crosses under the muscle and appears again on its
inner side, and here has the fourth nerve lying close
along it.

182. Follow the fourth nerve forward till it enters
the superior oblique muscle, and then trace out the origin
and insertion of the latter; it arises from the frontal
bone immediately in front of the membranous inter-

THE CRANIAL NERVES. 73

orbital septum, and is inserted upon the upper suface
of the eyeball. }

188. Divide and reflect the superior rectus, looking
for the small branch of the third nerve which enters it,
and then trace the ophthalmic nerve through the orbit,
pushing aside other parts which come in the way, but
not dividing them.

a. Soon after it enters the orbit, the ophthalmic
trunk divides into a larger and smaller branch.
The former crosses above the optic nerve and
beneath the superior oblique muscle ; in front
of the orbit it passes over the Harderian gland,
and, on dividing and removing the superior
oblique muscle, may be traced forward between

_ the gland and the inner boundary of the orbit
fil it~ prerces the latter. ta enter the: nasal
chamber.

6, Thesmaller or ventral division of the ophthal-
mic trunk, turns mesially below the optic nerve,
and there enters the ophthalmic ganglion. ‘The
ganglion is also joined by a considerable branch
from the third nerve, which lies here to the in-
ner side of the ophthalmic branch. From the
ganglion a number of cz/iary nerves run forward
to the eyeball. They may be traced by raising
and turning forward the optic trunk.

184, As the ophthalmic nerve enters the eyeball it
lies on the external rectus muscle, which arises from
the hollow on the inner surface of the base of the skull
under the anterior clinoid processes, and passes forward
to be inserted on the outer side of the eyeball. Care-

4

74 ANATOMY OF A CHELONIAN.

fully separate the outer surface of the posterior portion
of this muscle from the side of the skull against which
it lies, and note the sixth nerve entering it. Trace the
nerve back till it disappears in the bone (180, 2).

185. Clean the énternal rectus muscle which passes from
the posterior part of the inter-orbital septum to the in-
ner side of the eyeball. On its course it crosses over
the Harderian gland. Detach the muscle from the eye-
ball, carefully turn it back, and note the branch of the
third nerve which enters its under surface. :

186. Note the /achrymal gland on the outer side of
the eyeball, and then, separating it and the Harde-
rian gland from the globe, expose the pyramidalis mus-
cle. Its fibres arise from the inner side of the eyeball,
arch over the optic nerve, and then turn down and
around the latter and the external rectus to be inserted
into the lower eyelid and the nictitating membrane.

187. Remove the lachrymal gland; raise the eyeball
and note the zuzferior oblique muscle, placed transversely
near the front of the orbit; it arises from the lower
part of the inner wall of the orbit, and is inserted upon
the outer side of the eyeball. As the eyeball is being
raised note more closely the nictitating lid, and the
fibrous prolongation from its lower margin to the py-
ramidalis muscle, which will now be better seen than
previously.

188. Turn the eyeball back (dividing any fibrous
bands that interfere) so as to expose its under surface,
with the insertion of the zzferior rectus muscle upon it.

THE CRANIAL NERVES. 75

Then trace the muscle back below the optic nerve to
its origin from the base of the skull beneath the ante-
rior clinoid processes.

189. Pushing the eyeball aside, trace forward below
it the branch of the third nerve which enters the in-
ferior oblique muscle near its origin. Then remove
the eyeball and its muscles entirely.

190. Seek in the loose tissue covering the floor of
the orbit for the superior maxillary nerve, a branch of
the fifth cranial. Having found it, cut away the bony
arch covering in the temporal fossa, and trace the nerve
back through the mass of muscles occupying that re-
gion of the skull, until it reaches its foramen of exit
(27, 4); then, carefully cutting the bone away as re-
quired, trace the trunk to the Gasserian ganglion. Im-
mediately after passing out of the skull, the nerve gives
off a branch which enters the muscles lying around it.
It then runs forward to the orbit, which it enters at its
inner side and close to its floor, and there divides into
two branches. The smaller of these passes forward
and outward, and disappears through a foramen in
the anterior region of the floor of the orbit. The lar- -
ger branch runs forward in a more internal course and
passes through the membranous region (29) of the or-
bital floor to enter the nasal cavity.

191. The inferior maxillary nerve leaves the skull by
the same foramen as the superior, and may there be
readily found on the ventral side of the latter and
traced back to the ganglion. After getting outside the
skull it gives off several small branches to the neigh-

76 ANATOMY OF A CHELONIAN,.

boring muscles, and a somewhat larger one, which
passes forward and enters the ¢emporal muscles near the
articulation of the mandible.

a. The remaining principal portion of the nerve
then runs downward and forward to the slit in
the upper side of the ramus of the lower jaw
(53), and divides into two branches,which en-
ter it.

6. The larger anterior branch runs forward in
the mandible, giving off branches in it, and
appears again on its inner side, just above
Meckel’s cartilage (54, @), where that first
comes into view on the mesial side of the
ramus of the mandible. It is then distributed
to parts in the floor of the mouth.

c. The posterior division of the inferior maxillary
nerve runs down nearly vertically through the
ramus of the mandible and reappears on its
inner side, near the lower border of the bone,
through a special foramen (53), and is then
distributed to the neighboring soft parts.

192. Trace back the sixth nerve, from the part al-
ready seen in the orbit till it enters the basisphenoid,
and then follow it, by breaking away the bone with
great care. The nerve, while in its bony channel, will
be found to receive a branch from the Gasserian gan-
glion, which passes in through a minute bony canal, and
a small ganglion is placed at the point of junction. From
this ganglion three branches arise. Trace them out.

193. Taking now a fresh terrapin, chloroform and
open it in the manner already described (77).

THE CRANIAL NERVES. 7/7

Extend the neck, divide the skin along the ventral
median line, and reflect it. Remove the heart and
alimentary canal, except the gullet, but leave the lungs
and air-passages and the cesophagus undisturbed ; cut
away the ventral half of the pectoral girdle, but do not
injure the brachial plexus (159). Carefully remove the
skin covering the hyoidean apparatus between the rami
of the mandible, and treat similarly the superficial mus-
cular layer beneath it.

194. The anterior hyoid cornu will now readily be
felt through the muscles which lie on it, running par-
allel to the mandible on each side. At the dorsal end
of this cornu, and near its posterior border, will be
found three nerve-trunks, which are now to be care-
fully dissected to their peripheral distribution.

a. One ofthese is the hypoglossal. It passes for-
ward and divides into an external branch, dis-
tributed to the muscles on the anterior side
of the cornu, and a lingual division which
may be traced on to the tongue-muscles, giv-
ing off a few filaments on its way.

b. Near the hypoglossal, at the point where it
first appears in the above dissection, but lying
closer to the anterior hyoid cornu, the glosso-
pharyngeal nerve will be found; trace it on to
its distribution in the space between the two
hyoid cornua; one especially prominent
branch runs along the posterior border of the
anterior horn.

c. Still another nerve will be found near the
proximal end of the cornu, and close against
its posterior border; it is a branch of the

78 ANATOMY OF A CHELONIAN.

seventh nerve, and turning around the cornu
may be traced into a muscle which passes
from that to the proximal end of the mandible
on the same side.

195. Divide the hyoidean apparatus, the larynx, and
the ventral walls of the pharynx and gullet in the me-
dian line, and turn the halves outward so as to expose
the base of the skull, covered by the mucous mem-
brane of the roof of the mouth and pharynx. Then
proceed to trace the nerves described below, taking the
ereatest care not to injure the rest while following one >
of them.

196. Find the pneumogastric in the neck (99), where
it has already been seen with the carotid artery and the
cervical sympathetic accompanying it. Trace all three
from that point to the base of the skull, where the ar-
tery (crossed on its course by several nerves, which
must not be cut) passes out of sight, entering the ca-
nal which opens just behind the proximal end of the
quadrate-bone (26, ¢). Then cut away the artery, dis-
entangling it from the nerves around.

197. Next trace the pneumogastric nerve up to the
skull (for its peripheral distribution see section 100).
It will be seen to enter a ganglion (superior cervical
ganglion of the sympathetic) which lies on the base of
the skull, immediately posterior to the cartilaginous
floor of the tympanum.

198. Next trace back the hypoglossal from the point
where it has already been seen (194, @); it crosses on

THE CRANIAL NERVES. 79

the dorsal side of the pneumogastric, and is attached
to it at that point. Beyond this follow it till it enters
its foramen in the occipital bone (25, 4).

199. Follow the sympathetic trunk along the upper
half of the neck. Near the skull it separates from the
pneumogastric, and lies to its outer side; crossing
ventrally to the hypoglossal, it divides into an inner and
outer branch. The former enters the ganglion (197) ;
the latter proceeds alongside the carotid, and disappears
through a foramen in the base of the skull (26, /) placed
just internal to that through which the carotid disap-
pears.

200. A short way anterior and external to the supe-
rior cervical ganglion, the seventh nerve will be found
passing out from its foramen immediately in front of
the opening of the carotid canal; it then runs to the
proximal end of the anterior cornu of the hyoid. In
its course it presents a small ganglion, from which two
branches proceed; one is that already seen curling
around the hyoid cornu to enter the digastric muscle
(194, ¢); the other is distributed along the posterior
border of the mandible.

201. Trace the glosso-pharyngeal nerve (194, 4) to-
ward the skull; it will be found to enter the superior
cervical ganglion.

202. Two small branches in this region still remain
for description : one runs back from the superior cer-
vical ganglion to the gullet, and is probably to be
regarded as an @sophageal branch of the pneumogastric ;

80 ‘ANATOMY OF A CHELONIAN.

the other (descendens noni) arises from the hypoglossal,
close to its foramen of exit, and runs back among the
muscles of the neck.

203. Repeat on the other side the dissections given
in sections 196-202, inclusive, and then, with a pair
of bone forceps break away the base of the skull in
the middle line, so as to expose the ventral aspect of
the medulla oblongata; with care this can be done
without injuring the nerves above described, which are
then to be followed into the cranial cavity, bits of bone
being broken away as may be necessary, with strong
scissors or a stout needle mounted ona handle. The
hypoglossal may thus be followed to its superficial
origin (180, 7); the pneumogastric, spinal accessory, and
glosso-pharyngeal traced from the superior cervical
ganglion to the brain; and the seventh nerve followed
through the bone in front of the auditory capsule to the
cranial cavity. Then remove the eyeballs, and cut off
the head and the upper part of the neck and place
aside in strong alcohol to harden the brain.

204. To study the Anatomy of the Eyeball, clean away
the muscles, etc., from its exterior. Note:

a. The transparent cornea in front, forming a seg-
ment of a smaller sphere than the semi-opaque
sclerotic behind, which has a bluish tint from
the choroidal pigment seen through it. In the
anterior part of the sclerotic bony plates may
be felt imbedded in it, forming a ring just where
it meets the cornea. The conjunctiva on the
front of sclerotic contains much dark pigment.

&. Cut away the cornea; note the anterior cham-

Pek

THE EVE. SI

ber of the eye between it and the front of
the lens, and filled with the agucous humor.

. Also the brown and gold 277s, projecting into

the anterior chamber, and overlapping the
margins of the lens; it surrounds the circular
pupil.

The crystalline lens may now be exposed on its
anterior aspect by fastening the eye, with its
anterior side upward, by pins to a layer of
wax in the bottom of a dish, covering it with
water, and then cutting away the iris. Next

‘ remove the lens, and note its bi-convex form.

After removing the lens, the wtreous humor
will be seen.
Take away carefully the vitreous humor, and

observe the retina, with its delicate vessels,

behind it. Detach the retina from—

The pigmented chorord outside it.

As the retina is raised note the point where
the optic nerve is attached to it. .
Raise the choroid, and the inner surface of the
sclerotic coat will come into view behind it.

205. After twenty-four hours, proceed to break away

the remainder of the base of the skull, and also the
bodies of two or three of the anterior cervical verte-
brz ; take care of the various nerves attached to the
brain and spinal cord. As the bone below the inter-
orbital septum is removed, note above it a cartilaginous
rod (¢rabecula cranii, or naso-ethmoidal cartilage) which
passes forward, and between the nose-chambers ex-
pands into a vertically placed cartilaginous lamella,
the representative of the ethmoid. This may not have

4*

82 ANATOMY OF A CHELONIAN.

been seen hitherto, as it is apt to be removed in prepar-
ing the skeleton (28). Cut it away, with those orbital
muscles which arise from the floor of the brain cavity,
and expose the optic nerves.

206. Clear away the dura mater which closely in-
vests the exposed ventral part of the cord and of the
mid-brain. Then study the general outline of the brain
as now seen from its ventral aspect. Note:

a. In front, the olfactory lobes (170).

5. Behind them, in the middle line, the optic com-
missure, from which the optic nerves diverge an-
teriorly and the optic tracts behind.

¢. Between the optic tracts, the pituztary body or
hypophysts cerebrt.

@d. Meeting at the base of the olfactory lobes in
front, but diverging behind, so as to embrace
between them the pituitary body and optic
tracts, the large prosencephalic lobes (cerebral
hemispheres).

e. Between these, bearing the zzfundibulum, or
stalk of the pituitary body, and bounded by
the optic commissure in front, is the ventral
aspect of the ¢thalamencephalon.

jf. On the sides of the thalamencephalon, and
passing dorsally beneath the optic tracts, are
the crura cerebri, forming the ventral portion
of the mid-brain.

g. Behind the mid-brain are the anterior pyramids
of the medulla oblongata, with a furrow between
them, continuous behind with the anterior fis-
sure of the spinal cord.

4. Dorsal to the medulla, and projecting slightly

THE BRAIN. 83

beyond it on each side, will be seen a portion
of the cerebellum.

207. Remove the brain entirely from the skull cav-
ity, breaking away the bones as may be required.
Note that, on its dorsal aspect, the dura mater adheres
closely to it as far back as the prosencephalic lobes ex-
tend, and that so far there is no separate periosteum
for the inner surfaces of the cranial bones. Farther
back, on the contrary, the membrane splits into two
layers, one of which adheres to the bones as a thin
membrane while the other invests the brain as a sep-
arate dura mater, and between the two there is a con-
siderable space.

208. Remove the dura mater, the pineal gland, and
the processes of the meninges which dip between the
main subdivisions of the brain, and study the parts of
the encephalon carefully (170-179). Now that it is re-
moved from the skull and hardened, it can be better
examined than before. Note: 2

a. The olfactory lobes (rhinencephalon), which are
separated by a shallow groove from one an-
other and from the prosencephalon.

é. Beginning on the dorsal side, push apart the
prosencephalic lobes where they lie in contact
in the middle line, until the optic commissure
comes into view; note the absence of any
corpus callosum uniting them.

c. The posterior end of each cerebral hemisphere
(prosencephalic lobe) is free, and. diverges from
the median plane so as to pass outside the
mesencephalon, to the posterior border of

84

h.

‘

ANATOMY OF A CHELONIAN.

which it nearly extends; on its dorsal aspect
*the mesencephalon is not overlapped at all
by the prosencephalon.

In the angle between the mid- and fore-brains,
the small optic thalami are seen touching one
another in the median line.

The mesencephalic or optic lobes (corpora bigem-
ina), much smaller than the prosencephalic,
are paired hemispherical eminences, white on
the surface, and placed on the dorsal side of
the brain.

Behind the corpora bigemina, and rather lar-
ger than both together, is the cerebellum, only
attached to the rest of the brain by its anterior
margin, and overhanging the fore part of the
medulla oblongata. There is a slight notch in
its posterior border, from which a shallow,
wide median furrow proceeds forward some
way on its dorsal aspect.

Raising the hinder part of the cerebellum, note
the medulla oblongata, with the fourth ventricle
on its dorsal side, tapering off posteriorly into
the calamus scriptorius. Note the two parallel
cords of white nerve-substance lying side by
side along the floor of the fourth ventricle ;
they are continuations of the anterior columns
of the spinal cord.

On the side of the brain, note the relations of
the various parts already described, and trace
the white band of the optic tract up to the
mesencephalic lobe.

Pushing the posterior free end of the prosen-
cephalic lobe out of the way on one side, di-

THE BRAIN. 85

vide the optic tract, and trace beneath it the
crus cerebrt passing up into the prosencephalic
lobe.

209. Carefully push apart those parts of the brain
between which there is a median fissure, and then, with
a sharp, thin-bladed knife divide the whole organ, with
the piece of spinal cord attached to it, in the median
dorso-ventral plane. On the inner surface of the sec-
tions note:

a. The continuity of the fourth ventricle with the
central canal of the spinal cord.

6. The form of the cut edge of the cerebellum,
as now exposed, which shows that that organ
is a thin arched lamina.

¢. The passage (agueduct of Sylvius) from the front

end of the fourth ventricle to the third, and
the communications of this passage with large
cavities in the interior of the optic lobes.

ad. The third ventricle, bounded on each side pos-
teriorly by the flat inner surface of an optic
thalamus. Farther forward will be found on
each side an aperture (foramen of Monro)
leading into the /ateral (first and second) cere-
bral ventricles, one beneath each prosencephalic
lobe.

210. Make cross sections of one half of the brain
at different points to see the relations of the parts and
the distribution of white and gray matter.

211. Now dissect the reproductive organs of your
present specimen (sections 121-137, or 138-141, accord-

86 ANATOMY OF A CHELONTAN.

ing to sex). Donot make the dissections of the kidneys
or of the veins running to them, or of the inferior cava,
as these parts are alike in both sexes and the sympa-
thetic is apt to be injured in examining them.

212. Dissect out the Sympathetic Chain on one side.
Find the main cord in the neck, where it separates from
the pneumogastric (99). Following it, it will be seen
to pass outward and backward, and to have on it a
large ganglion (middle cervical), from which several
branches proceed. One of them is larger than the rest,
and forms obviously the backward continuation of the
main trunk; it proceeds toward the axilla. Amputate
the fore limb at the middle of the humerus, and care-
fully expose the brachial plexus. The sympathetic
cord runs toward this, and, before reaching it, presents
a third small ganglion (inferior cervical); crossing the
plexus it then enters a large fusiform ganglion (gan-
glion stellatum) placed on the ventral side of the most
posterior of the main trunks of the brachial plexus.

213. Apparently proceeding from the ganglion is a
small nerve, which runs to the ventral aspect of the
lung and there ends in the muscular layer covering
this organ. The nerve probably gets filaments from
the ganglion, but careful dissection will show that it is
mainly derived from the trunk of the brachial plexus
on which the ganglion lies.

214. From the posterior end of the ganglion stellatum
two filaments run back, one on each side of the sub-
clavian artery. They enter a ganglion which lies just —
anterior to the first dorsal nerve, and is connected with

THE SYMPATHETIC. 87

it by a communicating branch. From this ganglion
the sympathetic cord runs back, crossing the neck of
the second rib ; and, in the hollow between this and the
third, lies on and adheres to the ganglion of the second
dorsal spinal nerve (165).

9215. Thence the trunk continues to the neck of the
third rib, and on it divides into an external and larger
branch which enters the muscular layer of the lung,
and a smaller one, which continues the direction of the
main trunk toward the next spinal ganglion, to which
it is not directly adherent, but just beyond which it
receives a large communicating branch from this gan-
glion.

216. The sympathetic cord, still running posteriorly,
divides again into a larger outer division, which runs
to the lung musculature, and a smaller inner, which
passes by the fourth spinal ganglion and gets a com-
municating branch from it, a small ganglion being
found at point of union. The common cord thus
formed gives a slender outer branch to the lung, and
an zzner, which runs back and gets a branch from the
fifth dorsal spinal ganglion, there being a ganglionic
enlargement at the point of junction.

217. From the last ganglion three branches run
back. One (outer) passes to the dorsal aspect of the
kidney, running in the peritoneum; one (internal)
enters the tissues about the dorsal aorta; the median
and largest continues the chain back, and. passes to-
ward the flat surface of the kidney, which lies against
the vertebral column. Before reaching this, it gives

838 ANATOMY OF A CHELONIAN.

off a large outer branch, distributed to the kidney and
genital glands, while a slender inner filament runs back
on the median surface of the kidney and there gets the
communicating branches from the sixth and seventh
dorsal spinal ganglia, there being a well-marked sym-
pathetic ganglion, which gives off branches to neigh-
boring parts, at the point of union. From this ganglion
the sympathetic chain passes to another which lies
on the same surface of the kidney farther back, and
receives a long, communicating filament from the
eighth dorsal spinal ganglion. From the most poste-
rior ganglion on the kidney the main sympathetic cord
runs to another, placed a short way posterior to that
organ, and getting a communicating branch from the
ninth dorsal spinal ganglion, The sympathetic trunk
then runs back, and becomes connected with the first
trunk of the sciatic plexus close to its ganglion.

218. In the caudal region a longitudinal nerve-cord

unites the spinal nerves, and is, perhaps, a continuation
of the sympathetic chain.

END,

INDEX.

Pag siege viscera, 39

Abducens (fourth cranial) nerve,
67, 71, 76

Accessorius (eleventh cranial) nerve,
71, 76

Accessory bladders, 52

Aditus laryngis, 8, 57

Adrenal body, 55

Air-cells of lungs, 59

Alisphenoid bone, 25, 29

Angular bone, 27

Anterior abdominal veins, 36, 40

Anterior clinoid process, 24

Anterior nares, 7

Aorta, dorsal, 45, 47; left, 42, 45,
57; tight, 42, 45, 57

Apparatus, hyoidean, 7, 30

Aqueduct of Sylvius, 85

Aqueous humor, 81

Arch, pectoral, 31; pelvic, 33

Arches, neural, of dorsal vertebre,
I}

Artery, ascending cervical, 43; ax-
illary, 43; brachial, 43; common
carotid, 43, 44, 78; coronary, of
stomach, 45; coronary, of heart,
48 ; epigastric, 47; external caro-
tid, 19, 20, 43; gastric, 45; gas-
tro-duodenal, 46; gastro-epiploic,
45, 46; genital, 47; iliac, 47; in-
ferior mesenteric, 48; innomi-
nate, 42; internal carotid, 20; in-
ternal mammary, 43;
atico-duodenal, 46; pulmonary,
42, 48, 56; renal, 47; sciatic, 48;
subclavian, 42; superior cervical,
43; superior mesenteric, 41, 46;
thyroid, 43

Articular bone, 27

Arytenoid cartilage, 58

pancre- |

Astragalus, 34

Atlas vertebra, 17

Attrahens pelvis muscle, 36
Auditory (eighth cranial) nerve, 67
Auditory organ, 68

Auricles of heart, 39, 41

Axis vertebra, 17 ~

Eee of skull, 19

Basi-occipital bone, 24, 28

Basi-sphenoid bone, 24, 28

Bladder, accessory, 52; gall, 39;
urinary, 38, 40, 52

Bones of carapace, 11; of fore-limb,
31; of hind-limb, 34; of mandi-
ble, 26; of pectoral arch, 31; of
pelvic arch, 33; of plastron, 16;
of skull, 22

Bony skeleton, It

Brachial artery, 43 ; plexus, 61

Brain, 64, 70, 82

Bronchus, 59

Buccal cavity, 8

ee 40, 47

Calamus scriptorius, 84

Calcaneum, 34

Canals, semicircular, 69

Carapace, 6, II

Carotid arteries, 19, 20, 43, 44, 78

Carpalia, 33

Carpus, 32

Cartilage, arytenoid, 58; crico.
thyroid, 58; Meckel’s, 26; naso-
ethmoidal, 21

Caudal nerves, 61; vein, 38; ver-
tebre, 18

gO

Cavum arteriosum, 56; pulmonale,
56; venosum, 56

Centra of dorsal vertebrez, 12

Central plates, 10

Centro-lateral plates, 10

Cerebellum, 65, 70, 84

Cerebral hemispheres, 65, 70, 82, 83

Cerebral ventricles, 70, 84, 85

Cervical enlargement, 62; spinal
nerves, 61

Cervical vertebrz, 16

Characters, zoélogical, of Saurop-
sida, =

Chelonia, characters of, 4

Choroid coat of eye, 81; plexus, 70

Ciliary nerves, 73

Claws, 9, 10

Clavicle, 16

Clitoris, 55

Cloaca, I0, 51

Cochlea, 69

Colon, 46, 47

Columella auris, 20, 68

Common carotid, 43, 44, 78; iliac, 47

Condyle, occipital, 18

Conjunctiva, 80

Cord, spinal, 62

Cornea, 80

Coronary artery of heart, 49; of
stomach, 45; vein, 49

Coronoid bone, 27; process, 26

Corpora bigemina, 70, 84 ; Caverno-
sa, 51, 55

Costal plates, 12, I5

Cranial nerves, 70

Cricothyroid cartilage, 58

Crus, 9, 34

Crus cerebri, 70, 82

Crystalline lens, 81

Cuneiform bone, 32

Cystic duct, 41

| es bone, 27

Dermic bones of carapace, 11; of
plastron, 16

Descendens noni, 79

Diaphragm, 58

Digits of manus, 9, 33; of pes, 9,

34

Dorsal aorta, 45, 48; spinal nerves,
61; vertebrez, II

Duct, cystic, 41; of Miller, 53;
pancreatic, 41

INDEX.

Duodenum, 49
Dura mater, 62, 83

Tek 68

Eighth cranial (auditory) nerve, 67

Eleventh cranial (spinal accessory)
nerve, 67, 71

Epicoracoid, 31

Epidermic exoskeleton, 10

Epididymis, 52

Epigastric artery, 47

Epiotic bone, 23

Epiplastron, 16

Eustachian tube, 8, 68

Exoccipital, 24, 28

Exoskeleton, dermic, 11; epider-
mic, 10

External carotid, 19 ; characters, 6;
iliac, 48; jugular, 49; rectus, 73

Eyeball, dissection of, 80

Eyelids, 7

| eee (seventh cranial) nerve,

67, 71, 77; Vein, 49

Female reproductive organs, 55

Femoral vein, 37

Femur, 34

Fibula, 34

Fifth cranial (trigeminal) nerve, 67,
71

First cranial (olfactory) nerve, 70

Fissures of spinal cord, 63

Foramen lacerum posterius, 19, 28 ;
magnum, 18; obturator, 34; of
Monro, 85

Fore-limbs, 9, 31

Fossa, glenoid, 31; orbito-tempo-
ral, 18, 20

Fourth cranial (pathetic) nerve, 65,
66, 70; ventricle, 70, 84

Frontal bone, 25

"Gerace bladder, 39

Ganglia, Gasserian, 67, 71; inferior
cervical, 86; middle cervical, 86;
ophthalmic, 73; spinal, 63 ; supe-
rior cervical, 77; stellate, 86 -

Gasserian ganglion, 67, 71

Gastric artery, 45

INDEX,

Gastro-duodenal artery, 46

Gastro-epiploic artery, 45, 46

Genital arteries, 47; organs, female,
55; male, 50

Genito-urinary organs, 50, 55

Gland, Harderian, 65, 66

Glans penis, 51; clitoridis, 55

Glenoid fossa, 31

Glosso-pharyngeal (ninth cranial)
nerve, 71, 77, 79

Gullet, 59

2 ee gland, 66

Heart, 39, 41, 56

Hemisphere, cerebral, 65, 70

Hepatic vein, 42

Hind-limbs, 9, 34

Humerus, 32

Hyoidean apparatus, 7, 30, 58

Hyoplastron, 16

Hypoglossal (twelfth cranial) nerve,
71, 77, 78

Hypophysis cerebri, 82

Hypoplastron, 16

Ae bone, 33; arteries, 47

Ilium, 33

Inferior cervical ganglion, 86 ; max-
illary nerve, 75; oblique muscle,
74; pancreatico-duodenal artery,
46 ; rectus muscle, 74; vena cava,

54

Infundibulum, 82

Innominate artery, 42

Interior of skull, 28

Internal ear, 69; iliac artery, 47;
jugular vein, 44, 49; mammary
artery, 43; mammary vein, 50;
rectus muscle, 74

Interorbital septum, 21, 65

Intestine, 39, 40, 41, 46

Iris, 81

Ischium, 33

1 hae 8

Jugal bone, 22
Jugular veins, 44, 49

OI

K NEY, 53

J ACHRYMAL gland, 74

Large intestine, 40, 41, 46

Larynx, 57

Lateral ventricles, 85

Left aorta, 42, 45,57; gastro-epi-
ploic artery, 46

Lens, 81

Limbs, 9, 31, 34

Liver, 39, 40

Lobe, olfactory, 65, 82, 83; optic,
see 84 ; prosencephalic, 65, 70, 82,

3

Lumbar plexus, 60; enlargement,
62

Lungs, 58

Lymph, 36; sinuses, 42

Mice reproductive organs, 50

Mandible, 26

Marginal plates, dermic, 12; epi-
dermic, 10

Maxilla, 25

Meckel's cartilage, 26

Medulla oblongata, 66, 70, 82, 84

Membrane, nictitating, 7; tympan-
ic, 8

Mesencephalon, 65, 70, 84

Mesenteric artery, 41

Mesentery, 40

Mesethmoid, 21

Metacarpus, 33

Metatarsus, 34

Midbrain, 65

Middle cervical ganglion, 86

Monro, foramen of, 85

Motor oculi (third cranial) nerve, 66,
70

Mouth, 7, 8

Miiller’s duct, 53

Muscle, attrahens pelvis, 36; exter-
nal rectus, 73; inferior oblique,
74; inferior rectus, 74; internal
rectus, 74; pectoral, 36; protrac-
tor of head, 60; pyramidalis, 74 ;
retractor of head, 59; retractor of
penis, 51; retrahens pelvis, 36;
superior oblique, 64, 72; superior
rectus, 66, 73

Q2

Myelon (spinal cord), 62
Myelon-cephalon (medulla oblon-
gata), 66, 70, 82, 84

N ARES, anterior, 7; posterior, 8,

19

Nasal chamber, 30, 64, 66

Naso-ethmoidal cartilage, 21, 81

Naso-prefrontal bone, 25

Nerves, abducens (fourth cranial),
67, 71, 76; auditory ao cra-
nial), 67; caudal, cervical
spinal, 61; ciliary, ie dorsal spi-
nal, 61; facial (seventh cranial),
67, 71, 77; glosso- pharyngeal
(ninth cranial), 71, 77, 78, 79; hy-
poglossal (twelfth cranial), 71, 77,
78; inferior maxillary, 75; motor
oculi (third cranial), 66, 70; olfac-
tory (first cranial), 70; ophthal-
mic, 65, 72, 73; optic (second cra-
nial), 65, 70; orbito-nasal, 65,
72, 73; pathetic (fourth cranial),
65, 66, 70; pneumogastric (tenth
cranial), 44, 67, 71; recurrent la-
ryngeal, 44; sciatic, 48, 60 ; spinal
accessory (eleventh cranial), 67,
71; suboccipital, 61; superior
maxillary, 75; sympathetic, 44,
79; trigeminal (fifth cranial), 67,
ZI

Neural arches of dorsal vertebre,
14; plates, 11; spines, II, 14, 17

Neuro- central sutures, IS

Nictitating membrane, 7 74.

Nuchal plates, dermic, 11;
mic, 10

epider-

O BTURATOR foramen, 34

Occipital condyle, 18

Oculo-motor (third cranial) nerve
66, 70

Odontoid process, 17

(sophagus, 59

Olfactory lobe, 65, 70, 82, 83; nerve,
(first cranial), 70

Opisthotic bone, 23, 29

Ophthalmic ganglion, 733.
65, 66, 67, 72, 73

Optic chiasma, 66, 82; lobe, 70, 84;
nerve (second cranial), 66, 70, 82;
thalamus, 84; tract, 66, 82

nerve,

INDEX,

Orbit, 67

Orbito-nasal (ophthalmic) nerve, 65,
66, 67, 72, 73

Orbito-temporal fossa, 18

Organs of reproduction, female, 55 ;
male, 50

Os articulare, 27; centrale, 33; fe-
bulare, 34; intermedium, 32, 34;
magnum, 33; pubis, 33; radiale,
33; tibiale, 34; ulnare, 32

Ovary, 55

Oviduct, 55

[Bee Bees bone, 25

Pancreas, 40, 41

Pancreatic duct, 41

Parietal bone, 24, 2

Pathetic (fourth cranial) nerve, 65,
66, 70

Pectoral arch, 31;

Pelvic arch, 33

Penis, 51

Pericardium, 35

Peritoneum, 36, 58

Phalanges of foot, 34; of hand, 33

Pineal gland, 70

Pisiform bone, 32

Pituitary body, 82

Plastron, 6, 16

muscles, 36

Plates‘ of carapace, II, 12, 15; of
epidermic skeleton, 10
Pleuro-peritoneal cavity, 35
| Plexus, brachial, 61; choroid, 70;
lumbar, 60 ; sciatic, 60

Pneumogastric (tenth cranial)
nerve, 44, 67, 71, 77

Portal vein, 40

Post-auditory process, 18, 19

Posterior nares, 8, 19; vena cava,

54

Post-frontal bone, 22

Precoracoid, 31

Premaxilla, 25

Process, anterior clinoid, 24; co-
ronoid, 26; odontoid, 17; post-
auditory, 18, 19

Prodtic bone, 23, 29

Prosencephalic lobes (cerebral
hemispheres), 65, 70, 82, 83

Pterygoid bone, 24, 29

Pubic bone, 33; symphysis, 33 _

Pulmonary artery, 42, 48, 56; vein,

48

INDEX.

Pupil, 81 .

Pygal plates, dermic, 12; epider-
mic, Io

Pylorus, 39

Pyramidalis muscle of eye, 74; of
pelvis, 36

ag ean bone, I9, 23

Quadrato-jugal bone, 22

peplls, 32

Rectum, 41
Recurrent laryngeal nerve, 44
Renal artery, 47; vein, 54; organs,

53

Reni-portal vein, 37, 38, 54

Reptilia, characters of, 2

Reproductive organs, female, 55;
_male, 50

Respiratory organs, 58

Retina, 81

Retractor muscles of head and neck,
59; of penis, 51

Retrahens pelvis, 36

Rhinencephalon (olfactory lobes),
65, 70, 82, 83

Ribs,” §3..

Right aorta, 42, 45, 57

Roots of spinal nerves, 63

Si eanea ribs, 14; vertebra, 14

Sauropsida, characters of, I

Scales, 10

Scaphoid bone, 33

Scapula, 31

Scapulo-precoracoid bone, 31

Sciatic artery, 48; nerve, 48, 60;
plexus, 60

Sclerotic, 80

Second cranial (optic) nerve, 66, 70,
82

Sella turcica, 24

Semicircular canals, 69

Semilunar bone, 32

Sense organs, 64, 68, 80

Septum, narium, 8; interorbital, 21,

5
Seventh cranial (facial) nerve, 67,
71,77

93

Sinus venosus, 39, 41

Sixth cranial (abducens) nerve, 67,
Ty: 76

Skeleton, If

Skull, 18

Small intestine, 39, 40, 46

Spinal accessory (eleventh cranial)
nerve, 67, 71; column, 12; cord,
62; ganglia, 63; nerves, 61;
nerves, roots of, 63

Spines, neural, 11, 14, 17

Spleen, 41

Splenial bone, 27

Squamosal bone, Ig, 22

Stellate ganglion, 86

Stomach, 39

Stylo-hyoid ligament, 57

Subclavian artery, 42; vein, 49

Suboccipital nerve, 61

Superior cervical artery, 43; cervi-
cal ganglion, 77 ; maxillary nerve,
75; mesenteric artery, 46; ob-
lique muscle, 64, 72; pancre-
atico-duodenal artery, 46; rec-
tus muscle, 66, 73; vena cava,
41, 49

Supra-occipital bone, 19, 23, 28

Surangular bone, 27

Sutures, neuro-central, 15 ; of cara-
pace, 14

Sylvius, aqueduct of, 85

Sympathetic nerve, 44, 79, 86

Symphysis, ischial, 33; pubic, 33

TA 9 38

Tarsalia, 34

Tarsus, 34

Temporal fossa, 18, 20

Tenth cranial (pneumogastric)
nerve, 44, 67, 71, 77

Testes, 52

Thalamencephalon, 66, 82

Thalami optici, 84

Third cranial (oculo-motor) nerve,
66, 70; ventricle of brain, 85

Thymus, 44

Thyroid artery, 43

Tibia, 34

Tongue, 8

Trabecula cranii, 21, 81

Trachea, 39, 57

Trapezium, 33

Trapezoid bone, 33

94 Sie 6 9 5S 09.

Trigeminal (fifth cranial) nerve, 67, 49; facial, 49; femoral, 37; he-

71 patic, 42; internal jugular, 44, 49;
Tube, Eustachian, 8 internal mammary, 50 ; of urinary
Twelfth cranial (hypoglossal) nerve, | bladder, 38; portal, 40; pulmo-

FIs FF, FO nary, 48; renal, 54; reni-partal,
Tympanic membrane, 8, 68 37, 38, 54; subclavian, 49
Tympanum, 20, 68 Vena cava inferior, 54; superior, 41,

49
Venous sinus, 39, 41
| cai 32 Ventricle of heart, 39, 41, 56
Ventricles, cerebral, 70, 84, 85
Unciform bone, 33 Vertebre, caudal, 18; cervical, 16;
Ureter, 55 | dorsal, 12; sacral, 14
Urethral groove, 51, 55 -| Vestibule, 69
Urinary bladder, 38, 40, 52; organs, | Viscera, abdominal, 39
52, 53) 54 Vitreous humor, 81
Vomer, 25

Ay efferentia, 53
yee: 39, 57
Vas deferens, 53
Vagus nerve (see pneumogastric)
Vein, anterior abdominal, 36, 40;
caudal, 28; cava inferior, 54; GB ea ho 16
cava superior, 41, 49; coronary,

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