Chapter XV: Introduction (4)

The medullary folds have a curious origin, difficult to explain without the use of figures. They are continuous posteriorly with the primitive streak, so that it is impossible to tell where the medullary groove ends and the primitive groove begins, unless the dorsal opening of the blastopore be taken as the dividing point.

The amnion develops rapidly, and entirely from the anterior end.

The blastopore or neurenteric canal is a very distinct feature of all the earlier stages up to about the time of closure of the medullary canal.

Preceding the ordinary cranial flexure there is a sort of temporary bending of the head region, due apparently to the formation of the head-fold.

During the earlier stages of development the anterior end of the embryo is pushed under the surface of the blastoderm, and is hence not seen from above.

Body torsion is not so definite in direction as in the chick, some embryos lying on the right side, others on the left.

Of the gill clefts, three clearly open to the exterior and probably a fourth also. A probable fifth cleft was seen in sections and in one surface view.

The first trace of the urinary system is seen as a dorsally projecting, solid ridge of mesoblast in the middle region of the embryo, which ridge soon becomes hollowed out to form the Wolffian duct.

The origin of the hypophysis and paraphysis is clearly seen; the latter projects backward.

No connection can be seen between the first rudiments of the sympathetic nerves and the central nervous system.

The lumen of the œsophagus is for a time obliterated as in other forms.

The choroid fissure is a very transitory but well-marked feature of the eye.

LETTERING FOR ALL FIGURES ON PLATES VI.-XXVIII.

_a_, head-fold of amnion.
_aa_, anterior appendage.
_ac_, anterior cardinal vein.
_al_, allantois.
_an_, anterior nares.
_ao_, aorta.
_aop_, area opaca.
_ap_, area pellucida.
_ar_, aortic arch.
_au_, auricle.
_b_, bulbus arteriosus.
_bc_, body cavity.
_blp_, blastopore.
_bp_, basilar plate.
_bv_, blood-vessel.
_c_, centrum of vertebra.
_ca_, caudal artery.
_ch_, cerebral hemisphere.
_cl_, cloaca.
_cn_, cranial nerve.
_cp_, posterior choroid plexus.
_cv_, cardinal veins.
_dc_, ductus Cuvieri.
_e_, eye.
_ec_, ectoderm.
_ec′_, thickening of ectoderm,
_en_, entoderm.
_en′_, endocardium.
_ent_, enteron.
_ep_, epidermal layer of ectoderm.
_epi_, paraphysis.
_es_, embryonic shield.
_f_, fronto-nasal process.
_fb_, forebrain.
_fg_, foregut.
_g¹⁻⁵_, gill clefts.
_gf¹⁻⁶_, gill folds.
_gl_, glomerulus.
_h_, head-fold.
_hb_, hindbrain.
_ht_, heart.
_i_, intestine.
_i′_, stomach.
_in_, infundibulum.
_ir_, iris.
_it_, iter.
_k_, kidney (metanephros).
_l_, remains of groove between secondary folds.
_la_, larynx (cartilages of).
_li_, liver.
_ll_, lower lid of eye.
_ln_, lens.
_lr_, inferior rectus muscle of eye.
_lu_, lungs.
_lv_, lens vesicle.
_m_, mouth.
_ma_, manus.
_mb_, midbrain.
_mc_, medullary canal.
_me′_, tip end of medullary canal.
_md_, mandibular fold.
_mes_, mesoderm.
_mes′_, myocardium.
_mf_, medullary fold.
_mg_, medullary groove.
_mk_, Meckel’s cartilage.
_mp_, muscle plate.
_ms_, mesentery.
_mv_, meatus venosus.
_mx_, maxillary fold.
_myc_, myocœl.
_n_, nasal invagination or cavity.
_na_, neural arch of vertebra.
_nc_, neurenteric canal.
_nl_, nervous layer of ectoderm.
_nt_, notochord.
_o_, ear vesicle.
_oc_, optic cup.
_oe_, œsophagus.
_on_, optic nerve.
_os_, optic stalk.
_ov_, optic vesicle.
_p_, pituitary body.
_pa_, posterior appendage.
_pan_, pancreas.
_pc_, posterior cardinal vein.
_pe_, pes.
_pg_, primitive groove.
_ph_, pharynx.
_pl_, pelvis.
_pn_, posterior nares.
_pr_, pericardial cavity.
_ps_, primitive streak.
_pt_, pecten.
_rt_, retina.
_s_, somites.
_sc_, spinal cord.
_se_, sphenethmoid cartilage.
_sf_, secondary fold.
_sg_, spinal ganglion.
_sm_, splanchnic mesoblast.
_sn_, spinal nerve.
_so_, somatic mesoblast.
_st_, stomodæum.
_sy_, sympathetic nervous system.
_t_, tail.
_ta_, trachea.
_tg_, thyroid gland.
_th_, thickening and posterior limit of _sf_.
_tn_, tongue.
_to_, tooth anlage.
_tr_, truncus arteriosus.
_tv_, third ventricle of brain.
_tv′_, third ventricle of brain.
_u_, umbilical stalk.
_ul_, upper lid of eye.
_ur_, superior rectus muscle of eye.
_v′-″-‴_, first, second, and third cerebral vesicles.
_va_, vascular area.
_vm_, vitelline membrane.
_vn_, ventricle of heart.
_vv_, vitelline blood-vessels.
_wd_, Wolffian duct.
_wdo_, opening of Wolffian duct.
_wr_, Wolffian ridge.
_wt_, Wolffian tubules.
_y_, yolk.

EXPLANATION OF FIGURES 1-26 ON PLATES VI.-XXVIII.

All of the figures, with the exception of the photographs and those copied by permission from S. F. Clarke, were drawn under a _camera lucida_.

The magnification of each figure, except those from Clarke, is indicated below.

The photographs were made by the author, and were enlarged for reproduction by the photographic department of the Smithsonian Institution. The other surface views were made, under the author’s direction, by Miss C. M. Reese.

With the exception of Stage III., all of the figures of any one stage are given the same number, followed where necessary by a distinguishing letter, so that it is possible to tell at a glance which section and surface views belong together. The transverse sections are all cut in series from anterior to posterior.

FIGURE 1. Surface view of egg. × ²⁄₃.

1_a_. Egg with part of the shell removed to show the chalky band in
the shell membrane. × ²⁄₃.

FIGURES 2 and 2_a_. Dorsal and ventral views respectively of the
blastoderm before the formation of the notochord, medullary folds,
etc. After Clarke.

2_b_-2_f_. Transverse sections of an embryo of the age represented in
Figures 2 and 2_a_. × 43.

3 and 3_a_. Ventral and dorsal views respectively of an embryo a few
days older than that represented in Figures 2 and 2_a_. After Clarke.

3_b_-3_m_. Transverse sections of an embryo of the age shown in
Figures 3 and 3_a_. × 43.

FIGURES 3_n_ and 3_o_. Two sagittal sections of an embryo of the same
stage as Figures 3 and 3_a_. × 43.

4 and 4_a_. Dorsal and ventral views respectively of a slightly older
embryo than the one shown in Figures 3 and 3_a_. Figure 4_a_ shows
only the head region. After Clarke.

5 and 5_a_. Dorsal and ventral views respectively of an embryo of
almost the same age as the preceding, to show the further development
of the medullary folds. After Clarke.

FIGURE 6. Dorsal view of an embryo only a day or two older than the
preceding. After Clarke.

FIGURES 6_a_-6_i_. A series of transverse sections of this stage. ×
43.

FIGURES 7_a_-7_h_. A series of transverse sections of an embryo
slightly older than the one shown in Figures 4-6. × 43. (No surface
view of this stage is figured.)

8 and 8_a_. Dorsal and ventral views respectively of an embryo with
five pairs of mesoblastic somites. × 20. (Drawn by transmitted
light.)

8_b_ and 8_c_. Two sagittal sections of an embryo of this stage. × 43.

FIGURES 8_d_-8_j_. A series of transverse sections of the embryo
represented in Figures 8 and 8_a_. × 43.

9_a_-9_m_. A series of transverse sections of an embryo somewhat more
advanced in development than the one represented in the last series.
× 43.

FIGURES 10 and 10_a_. Dorsal and ventral views respectively of an
embryo with eight pairs of mesoblastic somites. × 20. (Drawn chiefly
by transmitted light.)

FIGURE 11. Dorsal view of an embryo with fourteen pairs of
mesoblastic somites. The area pellucida and the developing vascular
area are shown, the latter having a mottled appearance. The pushing
of the head under the blastoderm is also shown. × 20. (Drawn chiefly
by transmitted light.)

FIGURES 11_a_-11_k_. A series of transverse sections of an embryo of
this stage. × 43.

FIGURE 12. Dorsal view of an embryo with about seventeen pairs of
mesoblastic somites. Part of the area pellucida is represented. (Both
transmitted and reflected light were used in making the drawing.) ×
13.

FIGURES 12_a_-12_g_. A series of transverse sections of an embryo of
this stage. × 43.

FIGURE 13. Surface view of an embryo with about twenty pairs of
mesoblastic somites. × (about) 15. (Drawn with both reflected and
transmitted light.)

FIGURES 13_a_-13_f_. A series of transverse sections of an embryo
slightly more developed than the one shown in Figure 13. × 20.

FIGURE 13_g_. A sagittal section of an embryo of about the age of the
one represented in Figure 13. × 20.

14. Head of an embryo with one pair of gill clefts; ventro-lateral
view. × 13.

15. Profile view of the head of an embryo with three pairs of gill
clefts. × 13.

FIGURES 15_a_-15_e_. A series of transverse sections of an embryo of
about the age of the one represented in Figure 15. × 20.

FIGURE 15_f_. A horizontal section through the anterior region of an
embryo of the age of that shown in Figure 15. × 20.

16. Surface view in profile of an embryo with four pairs of gill
clefts. × (about) 12.

FIGURES 16_a_-16_f_. A series of transverse sections of an embryo of
the approximate age of the one represented in Figure 16. × 20.

FIGURE 16_g_. A sagittal section of an embryo of the age (possibly
slightly younger) of the one represented in Figure 16. × 20.

17. Surface view in profile of an embryo at the time of origin of the
limbs. × (about) 5.

FIGURES 17_a_-17_g_. A series of transverse sections of an embryo of
the age of the one represented in Figure 17. × 7.

FIGURE 18. Surface view in profile of the head of an embryo slightly
larger than, though of about the same state of development as, the
one represented in Figure 17. Reproduced here chiefly to show the
gill clefts. × (about) 3.

19. Surface view of an embryo somewhat more developed than the one
just described. × (about) 3.

FIGURE 20. Surface view of an embryo older than the one represented
in Figure 19; with well-developed manus and pes. × (about) 5.

FIGURES 20_a_-20_j_. A series of transverse sections of an embryo of
the age of the one represented in Figure 20. × 7.

FIGURE 21. A photograph of a living embryo in the egg, showing the
allantois, yolk mass, etc. The embryo is somewhat more developed than
the one shown in Figure 20. × ²⁄₃.

22. A photograph of a still larger embryo, removed from the shell and
freed from the fetal membranes. × (about) 1.

23. A photograph of a still more advanced embryo, in which the digits
are quite evident and the scales are beginning to show. × (about) 1.

23_a_. A sagittal section of an embryo of the age of the one
represented in Figure 23; the tail has not been shown in this figure.
× (about) 3.

23_b_. A vertical section through the head of an embryo of about the
size (perhaps slightly smaller) of the one shown in Figure 23. ×
(about) 3.

24. A photograph of an older embryo in which the pigmentation of the
scales is evident, though not shown in the figure. × (about) 1.

25. A photograph of an embryo in which the pigmentation and the
development of the body form are practically complete. The
allantois, unabsorbed yolk, etc., have been removed. × (about) ³⁄₄.

26. A photograph of a just-hatched alligator, of an alligator egg,
and of a young alligator in the egg just before hatching. × (about)
³⁄₇.

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vol. 5, pp. 207-91, 1895 (?).

87. ---- “Zur Anatomie des Vorderarmes” (2d part), _ibid._, pp.
157-205, 1895.

88. ---- “Description anatomique de trois crocodiles envoyés de
Siam par les Pères Jésuites,” _Mémoires de l’académie Royale des
sciences_, vol. 3, part 2, p. 266.

89. ---- _Description anatomique d’un crocodile_, _ibid._, part 3, p.
173.

INDEX

Abdominal aorta and branches, 212

Abdominal ribs, 80

Acetabulum, 85

Air chamber of egg, 228

Albumen of egg, 229, 230

Allantois, 299, 300, 328

Alligator, 6
abundance of, 8
American, 3
and cane rat, 28
and muskrat, 28
attack from, 14
bellowing of, 18
catching of, 34
cave of, 12
Chinese, 38
Cynocephalus, 110
daylight hunting of, 33
dealers in, 34
derivation of name of, 40
differs from crocodile, 7
digging from cave, 33
distribution of, 10
economic importance of, 26
eggs used as food, 35
feeding of, 12
fire hunting of, 32
habitat of, 8
hatching of, for sale, 35
hibernation of, 12, 13
hides, annual output of, 28
for card cases, etc., 30
chief centers for, 27
damaged in removal, 31
Floridian, 28, 29
highest priced, 32
length and width of, 30
from Louisiana, 28, 29, 30
methods of cutting, 31
Mexican, 29, 30
removal of, 31
salting of, 31
shipment of, 31
from South and Central America, 27, 28
from Southern States, 28
varieties of, 29
value of different sizes of, 28, 29
value to hunter of, 28
hole, 11
hunting, 32
Joe, 9
killing of, 33
for sport, 27
laws for protection of, 28
leather, first used, 26
for shoes, 27
imitation, 32
present use of, 32
meat, preparation of, 35
smoking of, 36
use as food, 35
mississippiensis, 3, 7
raw hides, selling of, 32
sale of live, 34
sinensis, 3, 16
the stuffing of, 34
swimming of, 13, 14
tanned hides, sale of, 32
teeth, sale of, 34
value of, 34
trail, 11, 13
unknown to ancients, 40
use of tail, 14
value of live, 34

Alligatoridæ, 1

Amnion, 236, 247, 251, 259, 266, 267, 268, 269, 270, 274, 275, 278,
290, 334

Ampullæ, 149

Ancestry, 4

Annulus tympanicus, 149

Aortic arches, 203, 296, 299

Appendages, development of, 308, 315, 317, 327, 328

Appendicular skeleton, 81

Area opaca, 233

Area pellucida, 233

Arkansas Alligator Farm, 201

Arterial system, 212
first reference to, 44

Arteries, of anterior region, 215, 216
brachial, 218
caudal, 216
cervical, 220
cloacal, 316
cœliac, 212
collateralis colli, 217, 219
common carotid, 219, 221
crural, 216
dorsal aorta, 212
fibular, 214
first hæmorrhoidal, 216
gastric, 212
gastro-hepatico-intestinal, 212
iliac, 214
inferior dental, 223
injection of, 201
internal carotid, 70, 221
internal mammary, 217
ischiadicæ, 214
lingual, 220
lumbar, 213
mandibular, 220
mesenteric, 213
œsophageal, 217
pancreo-intestinal, 212
pelvic, 214, 216
pleural, 217
of posterior region, 213
primary carotid, 203, 218, 220
pulmonary, 203
radial, 218
rectal, 216
right subclavian, 203, 216
sciatic, 214
second hæmorrhoidal, 216
spleno-intestinal, 212
subclavian, left, 219
subscapular, 217
superior dental, 223
thoracic, 218
thyroid, 217
tibial, 214
ulnar, 218
urogenital, 214
vertebral, 217

Arytenoid cartilage, 147

Atlantosaurus, 4

Atlas, 53

Auditory capsule, 72

Auditory vesicle, 274, 277, 286, 294, 297, 302, 309, 320, 322

Auricles, 204

Axis, 54

Bartram’s account, 8

Basilar plate, 331

Belly skin, 31

Belodon, 5

Bile duct, 154

Bird and crocodile, 40, 41

Blastopore, 233, 234, 235, 236, 240, 246, 249, 250, 252, 257, 263,
264, 272

Body cavity, development, 279, 281, 287

Body flexure, 307, 317, 318

Bones, alisphenoid, 68
angular, 76
of anterior limb, 82
articular, 75
basilingual plate, 76
basioccipital, 67, 68, 72
basisphenoid, 67
calcaneum, 88
centrale, 84
clavicle, 82
coracoid, 81, 82
coronoid, 75
dentary, 74
epiotic, 73
epipubis, 86
episternum, 82
exoccipital, 70
fibula, 87
fibulare, see calcaneum
of foot, 88
frontal, 60
humerus, 82
hyoid, 76
ilium, 84
integumental, 50
interclavicle, 81
ischium, 85
jugal, 62, 67
lachrymal, 62
malar, 62
maxilla, 61, 64
mesethmoid, 72
metacarpals, 84
nasal, 60
opisthotic, 73
palatine, 65
parietal, 59
of pelvic girdle, 84
pisiform, 83
of posterior limb, 84
postfrontal, 59
prefrontal, 60
premaxilla, 61, 63
pro-otic, 73
pterygoid, 66, 70
pubis, 86
quadrate, 62, 69
quadratojugal, 64, 67
radius, 83
scapula, 81
splenial, 75
squamosal, 59
supra-angular, 75
supraorbital, 62
suprascapula, 81
tarsalia, 88
tibia, 87
tibiale-centrale, 88
transpalatine, 66
ulna, 83
ulnare, 80
vomer, 72

Brain, 132

Breeding habits of alligator, 18

Bronchial rings, 199

Buttons, 27

Caiman, 36
of Amazon, 37
banded, 3
black, 3, 36
latirostris, 3
niger, 3, 7
palpebrosus, 3
round-nosed, 3
sclerops, 3
species of, 37
spectacled, 3, 37
teeth of, 36
trigonotus, 3
ventral armor of, 36

Capitulum of rib, 78

Carpus, 83

Cauda equina, 131

Cement, 65

Centrum, development of, 325

Cerebellum, 132, 133

Cerebral hemispheres, 132, 133, 134
development of, 302, 309, 310, 332

Cerebral peduncles, 133, 134

Cerebral vesicles, 266, 273, 319

Cervical cord, 132

Chalky band of egg, 229

Chewing muscles, 90

Chinese alligator, 3

Chorda, tympani, 137

Choroid, 147

Choroid fissure, 321, 322, 337

Clarke, S. F., 226, 227, 228, 230, 231, 232, 233, 236, 243, 247, 250,
274, 293, 317, 318

Classification, 1

Claws, 46, 84
development of, 333

Cleavage of mesoblast, 263

Clitoris, 196

Cloaca, 155
embryonic, 316, 327

Cloacal glands, 156

Cocoa, Fla., 27

Columella, 74, 149

Conjunctiva, 136

Conjunctival gland, 146

Conus arteriosus, 203

Copulation of crocodile, 195

Copulatory organs, 194

Cornea, 146
development of, 321

Corn marks, 29, 30

Cornua of hyoid, 76

Corpora cavernosa, 194

Cranial cartilages, 320

Cranial flexure, 273, 276, 283, 291

Cranial nerves, 132, 135, 302, 320, 325

Cranium, 58

Cricoid cartilage, 197

Crocodile--Crocodilus, 6
African, 39
caves of, 41
distribution of, 40
egg laying of, 41
held sacred, 40
in Madagascar, 40
mentioned by Herodotus, 40
Voeltzkow’s account, 40
American, 2, 37
colors of, 39
distribution of, 38
Ditmars’ experience, 38
range of, 37
cataphractus, 2
Cuban, 2, 39
derivation of name of, 40
Guatemala, 2
intermedius, 2, 39
johnstoni, 2
Madagascar, 2
eggs of, 228
hatching of, 41
nest of, 41
man-eating, 40, 43
marsh, or mugger, 42
moreletti, 2
Nile, 21, 39
niloticus, 2, 39
Orinoco, 2, 39
palustris, 3, 42
migration of, 42
porosus, 2
rhombiferus, 2, 39
robustus, 2
rough-backed, 3
salt-water, 2, 42
in captivity, 43
habitat, 43
size of, 42
skeleton of, 51
sharp-nosed, 2
Siamese, 2
swamp, 3

Crocodilia, 1

Crocodilidæ, 1, 2, 3

Deaths by crocodiles in Africa, 40
in India, 43

Deltoid ridge, 83

Dentine, 65

Dermal skeleton, 47

Diaphragm, 115

Digestive system, 152

Digestive tract, fixation of, 159
histology of, 189
outline of, 158

Digits, development of, 329, 332

Dinosauria, 4

Dorsal aorta, development of, 277, 278, 327

Dorsal fissure, 131, 132, 133

Dorsal shield, 47

Drum, 148, 149

Ductus Cuvieri, 312

Ear, 147, 148

Ectoderm, 233

Eggs, 227, 231
artificial incubation of, 24
incubation of, 22
number of, per nest, 21, 22, 23
shape of, 228
shell of, 228
size of, 25, 227, 228
taken from oviduct, 24
variation in size of, 26
weight of, 25

Elizabeth Thompson Science Fund, 226

_El lagarto_, 40

Embryo, development of, 231
earliest stages of, 232, 233
position of, 230
removal of, from egg, 231
stages:
I., 233;
II., 235;
III., 240;
IV., 247;
V., 249;
VI., 257;
VII., 266;
VIII., 267;
IX., 273;
X., 282;
XI., 293;
XII., 293;
XIII., 300;
XIV., 307;
XV., 316;
XVI., 317;
XVII., 318;
XVIII., 328;
XIX., 328;
XX., 329;
XXI, 333;
XXII., 334;
XXIII., 334

Embryology, summary of, 335

Enamel, 65

Endoskeleton, 50

Enteron, development of, 261, 262, 269, 271, 278, 287

Entoderm, 234

Epidermal skeleton, 46

Epiglottis, 197

Episternum, 81

Epitrichial cells, 48

Eustachian tube, 72, 149

Everglades, 10, 220

External auditory meatus, 70, 73, 148

External mandibular foramen, 75

Extracolumellar cartilage, 74

Eye, 144
glands of, 144

Eyeball, 146

Eyelids, 144
development of, 329, 332

Feeding of alligators, 15

Fenestra ovalis, 73

Fissura ventralis, 131

Food of alligators, 15

Foramen ovale of skull, 68

Forebrain, 274, 276, 284, 291, 294, 302, 308, 319

Foregut, 240, 248, 252, 297

Foreskin, 195

Fort Pierce, Fla., 27

Fourth ventricle, 132

Fronto-nasal region, 318

Fundic region of stomach, 152

Gastroliths, 44, 45, 153

Gavial, 6
food of, 44
Indian, distribution of, 43
eggs and nest of, 44
meaning of, 44

Gavialidæ, 1, 3

Gavialis gangeticus, 2
character of, 43, 44
size of, 43

Genital ducts, 156

Geographical distribution of Crocodilia, 6

Gescmackwärzchen, 165

Gharial, 44

Gill clefts, 277, 283, 285, 293, 294, 299, 301, 302, 303, 316, 317,
318, 323, 336

Gizzard, 153

Glans penis, 195

Glenoid cavity, 81

Glomeruli, 304

Glottis, development of, 324

Growth of alligators, 16

Hallux, 88

Harderian gland, 136, 145

Head-fold, 233, 236, 237

Heart, 202, 204
development of, 267, 270, 279, 283, 287, 297, 303, 310

Hindbrain, 277, 284, 294, 308, 319

Histology of enteron, 157
of integument, 48

Horn alligator, 31

Horny layer, 48

Hyoid, 151
development of, 330

Hyomandibular cleft, 286, 307, 309, 322

Hypophysis, 53, 133
development of, 306, 320, 331, 337

Incubation, period of, 25

Infundibulum, 133, 134
development of, 330

Integument, histology of, 48

Internal auditory meatus, 73

Internal mandibular foramen, 76

Intestine, 154
development of, 289

Iris, 146
development of, 321

Jacksonville, Fla., 34

Kidneys, 192

Kissimmee, Fla., 27

Labyrinth, 148

Lachrymal canal, 145

Lachrymal gland, 144, 145

Lake Kissimmee, 10

Lake Worth, 37

Large intestine, epithelium of, 187
histology of, 186
_see_ Rectum

Larynx, 197
development of, 323

Lateral disks of stomach, 153

Lateral ventricle, developing, 319

Laying season of alligator, 18

Lens, 147

Lens vesicle, 276, 284, 294, 302, 309, 321, 332

“Leviathan” of Book of Job, 40

Liver, 154
development of, 304, 307, 312, 326

Lower jaw, 74

Lungs, 199, 200
capillaries of, 200
development of, 303, 304, 312, 331

Mandible, 74

Mandibular fold, 296, 301, 308, 317, 318

Manus, 84, 317, 318, 329

Mating season of alligator, 19

Maxillary process, 301, 308, 317, 318

Meatus venosus, 312

Meckel’s cartilage, 330

Medulla, 132

Medullary canal, 254, 255, 258, 259, 260, 262, 267, 268, 269, 270,
271, 272, 275, 282, 291

Medullary folds, 250, 251, 253, 254, 256, 258, 265, 266, 291
origin of, 336

Medullary groove, 236, 237, 238, 241, 242, 244, 245, 248, 250, 253,
255, 256, 263, 265, 313, 334, 336, 337

Medullary plate, 249

Melbourne, Fla., 27

Mesentery, development of, 299

Mesoderm, 234

Metanephros, 332

Miami, Fla., 27

Midbrain, 275, 276

Middle ear, 149

Mouth, 150

Muscles:
abdominal, 112
ambiens, 118
anconæus, 104
atlanti-mastoideus, 96
capiti-sternalis, 96
caput coraco-scapulare, 105
caput humerale mediale, 106
caput humerale posticum, 105
caput humeri laterale, 105
caput scapulare laterale, 104
carpo-metacarpalis, 111
carpo-metacarpalis V., 111
carpo-phalangei, 109, 110
carpo-phalangeus, 111
carpo-phalangeus primus digiti V., 111
caudali-ilio-femoralis, 120
caudi-femoralis, 121
cerato-hyoideus, 93
cervicalis adscendens, 96
collo-capitis, 94
collo-occipitis, 96
collo-scapularis superficialis, 97
collo-squamosus, 95
collo-thoraci-suprascapularis profundus, 98
coraco-antebrachialis, 101
coraco-brachialis, 101
coraco-ceratoideus, 92
costo-coracoideus, 93, 99
costo-scapularis, 94
costo-vertebralis lateralis, 94
costo-vertebralis medialis, 94
deltoideus scapularis inferior, 103
diaphragmatic, 115
dorsalis scapulæ, 103
of dorsal neck region, 94
dorso-humeralis, 102
dorso-scapularis, 97
episterno-ceratoideus, 92
epistropheo-vertebralis, 95
extensor hallucis proprius, 129
extensor ilio-tibialis, 118
extensor longus digitorum, 125
of eyeball, 146
femoro-tibialis, 119
flexor digitorum brevis, 128
flexor longus digitorum, 127
flexor tibialis externus, 122
flexor tibialis internus, 122
of forearm, 107
gastrocnemius, 126
humero-antebrachialis inferior, 102
humero-carpi-radialis, 108
humero-carpi-ulnaris, 108
humero-metacarpalis, 108
humero-radialis, 106
humero-radialis brevis, 108
humero-radialis internus, 107
humero-radialis lateralis, 109
humero-radialis longus, 107
humero-radialis medialis, 109
humero-ulno-phalangei, 110
ilio-femoralis, 120
ilio-fibularis, 119
ilio-ischio-caudalis, 130
intercostales, 115
intermaxillaris, 91
interosseus cruris, 128
ischio-femoralis, 123
latus colli, 92
maxillo-coracoideus, 93
maxillo-hyoideus, 93
metacarpo-phalangeus, 111
metacarpo-phalangeus I., digiti V., 112
obliquus abdominis externus, 112
obliquus abdominis internus, 113
occipito-cervicalis medialis, 94
occipito-epistropheus, 96
occipito-maxillaris, 91
pectoralis, 100
pectoralis minor, 100
peroneus anterior, 125
pisiformi phalangeus primus digiti V., 111
of posterior appendages, 118
pterygo-maxillaris, 91
pubi-ischio-femoralis externus, 123
pubi-ischio-femoralis internus, 124.
pubi-ischio-femoralis posterior, 124
quadratus lumborum, 115
rectus abdominis, 113
rectus internus, 115
rectus lateralis, 114
rectus ventralis, 113
retractor oculi, 137
rhomboideus, 99
of scapula, 96
scapulo-humeralis profundus, 103
sphincter colli, 91
squamoso-cervicalis medialis, 95
sterno-atlanticus, 97
subscapularis, 104
supracoracoideus, 100
of tail, 129
temporalo-maxillaris, 90
teres major, 103
tibialis anticus, 125
tibialis posticus, 128
transversus abdominis, 113
ulno-carpi-radialis, 109
ulno-radialis, 107
of ventral side of neck, 91

Muscle plates, 289, 297, 311, 325

Musk glands, 156

Myocardium, development of, 305

Myocœl, 256, 280, 281, 282, 311

Nasal passages, 151

Nasal pit, 294, 307, 310, 317, 322, 330

Nephrostome, 290

Nerves
abducens, 133, 134, 135, 137
acoustic, 133, 137
alveolar branch, inferior, 136
axillaris, 141
brachialis longus inferior, 141
brachialis longus superior (radialis), 141
brachial plexus, distribution of, 140
coraco-brachialis, 141
crural and ischiadic plexuses, 142, 143
cutaneus brachii et antebrachialis medialis, 141
cutaneus pectoralis, 141
dorsalis scapulæ (posterior), 141
facial, 133, 137
frontal branch, 136
glossopharyngeal, 134, 137
hypoglossal, 68, 134, 138
latissimi dorsi, 141
nasal branch, 136
oculomotor, 68, 133, 134, 135
olfactory, 135
optic, 68, 134, 135
pectoralis, 141
pneumogastric, _see_ vagus
postsacral, 142, 143
presacral, 142, 143
sacral, 143
scapulo-humeralis profundus, 141
spinal (1-4), 138, 139, 140
subscapularis, 141
supracoracoideus, 140
teres major, 141
thoraci inferiores, 140
trigeminal, 68, 133, 135, 136, 137
trigeminal, inferior maxillary branch, 136
trigeminal, ophthalmic branch, 136
trigeminal, superior maxillary branch, 136
trochlear, 133
vagus, 68, 134, 137

Nervous epithelium of ear, 149

Nervous layer of ectoderm, 259, 268

Nervous system, 131

Nest of alligator, compactness of, 21
construction of, 21
form of, 21
location of, 20
size of, 21
temperature in, 24

Neural arches, development of, 325, 331

Neural groove, _see_ Medullary groove

Neurenteric canal, 264, 267, 272, 275, 282, 336

New York Zoölogical Park, crocodilians in, 39

Nictitating membrane, 144

Notochord, 236, 238, 245, 248, 249, 251, 255, 256, 260, 263, 266, 269,
270, 285, 295, 306, 335

Nuchal shield, 47

Obex, 133

Oblique muscles, 146

Odontoid process, 52, 54

Œsophagus, 151, 152, 324, 330
cilia of, 174
epithelium of (feeding), 173
epithelium of (hibernating), 172
histology of, 168
transsections of (figures), 169, 170

Okefinokee, 10, 226

Olfactory bulb, 132, 133

Olfactory lobes, development of, 332

Olfactory tract, 132, 133, 134

Olivary enlargement of œsophagus, 151

Optic chiasma, 134
cup, 302, 309, 310, 321
lobes, 132, 133, 135
nerve, development of, 321
stalk, 302
tracts, 134
vesicle, 274, 276, 282, 294

Oral cavity, 150

Ora serrata, 147

Osteolæmus tetrapis, 3

Otic vesicle, _see_ Auditory vesicle

Outer ear, 148

Ova, 193

Ovary, 193

Oviducts, 156, 193, 194

Palm Beach, Fla., 9

Pancreas, 154
development of, 326

Papillæ of tongue, 150

Paraphysis, 132, 133
development of, 319, 320, 330

Pecten, 147, 321

Pectoral girdle, 81

Penis, shaft of, 194

Pericardium, 323

Periotic capsule, 73

Pes, 317, 318, 329

Petromyzon marinus, 157

Pharynx, development of, 277, 285, 292, 295, 299

Pigment, 333, 334

Pineal body, 132, 319

Pits in scales, 49

Pituitary body, _see_ Hypophysis

Plover and crocodile, 40

Posterior cardinal vein, development of, 298

Postorbital bar, 60

Prickle cells, 49

Primitive groove, 246, 249, 250, 256, 265, 267

Primitive spinal column, 326

Primitive streak, 233, 240, 246, 249, 250, 256, 265, 267, 275

Procœlia, 1

Pulp cavity of tooth, 65

Pupil, 146

Recessus cavi tympani, 149

Recessus scalæ tympani, 149

Rectum, 155
transsection of (fig.), 186

Rectus muscles of eye, 146
development of, 332

Respiratory organs, 197, 200;
(fig.), 198

Rete Malpighii, 48

Retina, 147
development of, 321

Retractor oculi muscle, 146

Ribs, 77

Rima auditoria, 148

Ring muscle, 157

Roof of mouth, 165
covering of (fig.), 166
glands of, 167
papillæ of, 167

Saccus naso-lachrymalis, 146

Scales, development of, 333

Sclera, 146

Scutes, 47

Semicircular canals, 149

Semilunar valves of stomach, 154

Sexual characteristics, 19

Sexual maturity, 17

Shell membrane, 228

Shell-tooth, 334

Sinus venosus, 202

Size of alligator, 16
at hatching, 16

Skeleton, 46, 50

Skin, 87

Skull, 58
dorsal aspect of, 59
lateral aspect of, 67
posterior aspect of, 70
sagittal section of, 72
ventral aspect of, 63

Smaller part of stomach, 153

Small intestine, 154
histology of, 179, 186
mucosa of (fig.), 184
transsection of (figs.), 181, 182, 183, 185

Smithsonian Institution, 226, 227

Somatapleure, 279

Somites, 251, 252, 256, 266, 267, 274, 282, 292, 300

Special sense organs, 144

Spinal cord, 131, 290, 291, 298, 311, 325
development of, 298

Spinal ganglion, development of, 299, 311, 312, 314, 331

Spinal nerves, 138

Splanchnopleure, 279

Stenosauria, 1

Sternum, 77, 80

Stomach, 152, 153
development of, 305, 326
glands of, 177, 179
histology of, 174
transsection of (fig.), 176

Stomodæum, 317, 322

Stratum corneum, 48

Supratemporal fossa, 57

Sympathetic nerves, 314, 325, 337

Systemic arch, 203

Tail, 317, 318, 329

Tailfold, 274

Tapetum lucidum, 146

Tarsus, 88

Taste papillæ, 165

Tear dots, 145

Teeth, 47, 64

Teleosauria, 1

Temperature range in swamps, 23

Tendon Achilles, 126, 127

Testes, 194

Thoracic ribs, 78

Thyroid gland, development of, 78, 269

Tomistoma schlegeli, 2
skeleton of, 51

Tongue, 150
covering of (fig.), 160, 161
development of, 333
epithelium of, 161
glands of, 160, 162, 163, 164
histology of, 157
papillæ of, 160, 165

Tooth, development of, 333
socket of, 64
structure of, 65

Torsion of body, 274, 336

Trachea, 197
development of, 324, 330
rings of, 198, 199

Trigeminal foramen, 78

Tuberculum of rib, 78

Tympanic cavity, 70, 73, 148, 149

Umbilical stalk, 300, 308, 317, 318, 333, 334

Ureter, 156, 193
development of, 290

Urogenital organs, 192, 196

Valves of outer ear, 148

Vasa deferentia, 156

Vascular system, 201
lettering for, 224

Veins, of anterior region (fig.), 209
anterior vena cava, 208
axillary, 210
brachial, 210
caudal, 207
coronary, 202
external jugular, 211
femoral, 206
hepatic, 202, 205
hepatic portal, 205
iliac, 206
inferior dental, 211
internal epigastric, 206
internal jugular, 208
internal mammary, 208
ischiadic, 207
lingual, 211
mesenteric, 205
muscular, 211
pancreatic, 205
of pes, 207
postbrachial, 210
postcaval, 202, 204
of posterior region, 204
precaval, 202, 208
pulmonary, 203
radial, 211
rectal, 207
renal portal, 207
subclavian, 210
subscapular, 210
superior dental, 211
thoracic, 210
vertebral, 208

Velum palatinum, 151

Venous system, 204

Ventricle, 203

Vertebræ, cervical, 51, 52
caudal, 57
lumbar, 56
sacral, 56

Vertebral column, 50

Vertebrarterial canal, 78

Vitelline blood-vessels, 267, 283

Vitelline veins, 270

Vitreous humor, 332

Vocal cords, 197

Voeltzkow, A., 228, 230, 231, 232, 334

Voice of alligator, 18
before hatching, 25

Warts, 49

Wolffian body, 289, 299, 304, 305, 307, 314, 316, 326, 331, 336
ducts, 280, 281, 289, 299, 314, 316
ridge, 299, 306, 314
tubules, 306, 313, 331

Xiphisternal horns, 81

Yolk of egg, 230

Transcriber’s Notes

Language inconsistencies and errors in spelling, capitalisation and
hyphenation and in the translations of terms have been retained,
except as mentioned under Changes below. The textual differences
between the list of illustrations and the illustration captions have
not been standardised.

Page 123, paragraph Pubi-ischio-femoralis Externus: (Plate III., Fig.
1, p. is. f. int., Plate IV., Fig. 1, p. is. f. int.) should possibly
read (Plate III., Fig. 1, p. is. f. ext., Plate IV., Fig. 1, p. is.
f. ext.).

Page 273-274: ... to the region of the midbrain (v²) ...: v² does not
occur in Plates XVIII. or XIX.; ... at the side of the forebrain (v′)
...: v′ occurs in Plate XVII.

Some of the numbers in round brackets refer to the bibliography at
the end of the text. In some bibliographical references the source
document shows blank spaces rather than first names.

Changes made

Footnotes and illustrations have been moved out of text paragraphs;
some ditto marks have been replaced with the dittoed text.

The references to plates (for example those after page 130) have been
standardised regarding the use of commas and italicised abbreviations.

Some minor typographical and punctuation errors have been
corrected silently, as have some minor lay-out and typographical
inconsistencies.

Page vii, items 10 and 11: captions of individual photographs have
been added.

Page 3: repeated footnote marker [2] removed from last column of
Caiman niger.

Page 51: ... skeleton of Tomistoma schlegali ... changed to ...
skeleton of Tomistoma schlegeli ....

Page 72, caption with Fig. 24: supraangular changed to supra-angular.

Page 87, caption with Fig. 29: tb¹ changed to tb′ cf. illustration.

Page 107: entsprect changed to entsprecht.

Page 165: Gescmackwärzchen changed to Geschmackwärzchen.

Page 258: ... as shown in Figures 9 and 9b. changed to ... as shown
in Figures 9a and 9b.

Page 343, item 12: Das Skelet der Krokodiliner changed to Das Skelet
der Krokodilinen.

Page 345, item 36a: experimentallen changed to experimentellen; item
47: struttura del cruore changed to struttura del cuore.

Page 347, item 67: des Menchen changed to des Menschen; item 70:
Auricular höcker changed to Auricularhöcker; item 80: Het. Institute
changed to Het Instituut.

Index: some spellings corrected to reflect the spelling as used
in the text (coranoid to coronoid, Cyanocephalus to Cynocephalus,
Gescmackwärzchen to Geschmackwärzchen).