Sclerotomic (intrasegmentalj fissure, 143 



Sclerotomite, 148, 149 



Scrotum, 319 



Scutes, 24, 29 



Sgillmm, 119, 204, 2-f4, 286, 310, 333, 334, 



335, 338 

 Scymus, digestive tract, 273 

 Second order bronchi, 280 

 Secondary interatrial septum, 339 

 Secondary palate, 76 

 Secretin, 382 



Secretion, by nephric duct. 318 

 Segmental arteries, 143 

 Segmental muscle cells, 1 1 

 Segmental nerves, 9 

 Segmentation of head, 400 

 Selachians. 20 

 Sella turcica, 41,51,354 

 Semicircular canals, 406 

 Semidentine, 228, 229, 230 

 Semimembranosus, 429 

 Semilumar valve, 343 

 Seminal vesicle, 318 

 Seminal receptacle, 335 

 Seminiferous tubule, 318 

 Semionotidae, 115 

 Semitendinosus, 428, 429 

 Sensory-canal system, 18, 88, 410. 414. 418 

 Sensory cells of otolith. 1 1 

 Sensory "field", 31 

 Sensory organ, on scale of Calotes (Lizard), 



222 

 Sensory papillae of barbels. 24 



of cirri. 5 

 Septomaxilla, 64, 76, 80, 85, 92 

 Septum lucidum, 384 

 Serosa, 203 

 Serratus, 432, 433 



anterior and posterior, 424 

 SERRES, 3 

 Sesamoid bones, 1 7 1 

 SEWERTZOFF, 139 

 Sex cords. 327 

 Sex hormones, 382 

 Sex reversals, 382 

 Seymouna, 22, 86, 88, 151, 174, 175. 178 



head skeleton, 90 



pectoral girdle, 173 



vertebrae, 152 

 Seymouriamorpha, see Seymouria 

 Shagreen, of scales, 229 



Shark (see also Squalus and Chondrichthyes), 

 1 19, 186, 21 1, 240, 379, 380, 381, 382, 

 392, 402, 410, 415, 416, 423 



aortic arches, 352, 353 



as primitive vertebrate, 444 



brain, 394 



chondrocranium, 120, 121 



circulatory system. 374 



development, 204 



dorsal diverticulum of esophagus, 285 



fin rays, 243 



head skeleton of, 1 19, 120 



hypobranchial musculature, 421 



kidney, 310 



muscles, eye, 423 



myomere, 421 



organogenesis, 203 

 reproductive system. 333, 334 

 sensory-line system, 412 

 teeth, 119 



urogenital systems, 335 

 vertebrae. 163 

 Sharpey's canals. 233 

 Sharpey's fibers, 221, 225, 229, 232, 235, 



243 

 Sheep, 212 

 Shell, egg. 201 

 Shine glands, 23 



Short extensors of digits II to V. 433 

 Shrew, 22 



Sigmoid sinuses, 360 



Silurian, 63, 125, 135, 137, 229. 246, 444 

 Siluroid fish, 418 



Simopteraspis, head and trunk skeleton. 138 

 Simple eye, 1 1 

 Simplex uterus, 323 

 Sinoatrial opening, 376 

 Sinoatrial node. 340 

 Sinus terminalis (terminal sinus), 203 

 Sinus venosus, 339 

 Siphons, 334 



Siredon, development of vertebrae. 156 

 Sixth aortic arch. 283 

 .Skeletal muscles. 420 

 Skeletogenous plate. 13 

 Skeletogenous rods, 13 

 •Skin, 217 



Skull table, skull roof, 96 

 Sloth. 141,323 

 Small intestine, 253, 256 

 Smooth muscles. 420 

 Snakes as lepidosaur. 61 

 Snapping turtle, see Chelydra 

 Snout, 37 

 Socket, 243 



Soederbergkia, form A, 155 

 Solenocyctes, 8, 197, 291, 382 

 Soleus, 430 



Somatic mesoderm, 201 

 Somatic peritoneum, 253 

 Somites, 143, 208, 420 

 Special somatic sensory fibers, 386 

 Special visceral sensory fibers, 386 

 Specialized features. 442 

 Spflerpes, 325, 326 

 SPENGEL, 5 

 Spermatic cord, 320 

 .Spermatogonia. 331 

 Spermatophores. 310. 334 

 Sphenethmoid commissure. 53, 122 

 Sphenodon, 22, 175, 176, 191, 280, 297, 347, 

 356, 363, 367, 369, 388, 403, 432 



as lepidosaur, 61 



body skeleton, 147 



digestive tract, 256 



external appearance, 28 



head skeleton, 65, 70, 71 



pectoral girdle, 173 



pelvic girdle, 176 



pes of Sphenodon. 175 



urogenital system, 296 



vascular system, head, 357 



vertebrae, 146, 147, 148, 148, 149 



Sphenoid, 37, 59 



Sphenopalatine foramen. 39. 48, 49 

 Sphenotic. 106 



Spinal accessory nerve (XI), 387 

 Spinal arteries, 354 

 Spinal plate, 184 

 Spmax,247, 271,381 

 Spine, fin, 23, 167 

 Spines of Tachyglossa, 2 1 8 

 Spinous cartilage, 130 

 Spiny ant-eater, see Tachyglossus 

 Spiracle, 23, 24, 288, 289, 290 

 Spiracular cleft, 94 

 pouch, 287, 288 

 Spiral valve, 264, 343 



development in shark, 276 

 Splanchnopleure, 381, 382 

 Splanchnic mesoderm. 201 

 Spleen (lien), 253, 264, 367, 378 

 Splenial bone, 76, 86 

 Spongy bone, 236 

 Squaloraja, 123 



Squalus, (see also shark), 20, 119, 120, 137, 

 182, 183. 225, 252, 285, 310, 311, 333, 

 334, 345, 351, 359, 374, 394, 395, 413, 

 422, 444 

 brain, 396 

 ceratotrichia. 242 

 cranial nerves, 398 

 development, 204 

 endocranium. 119 

 external appearance, 24 

 digestive tract, 257, 273 

 fin rays, 244 

 gut. development, 275 

 heart, 346 

 inner ear, 409 

 kidney, development, 311 

 pectoral and pelvic girdles and fin bases, 



187 

 reproductive system, 335 

 sensory-line system, 413 



development, 414 

 teeth, development, 247 

 vertebrae, 165 

 Squamates, 403 



Squamosal, 37, 49, 61. 76, 80, 82, 85, 96 

 two centers in frog, 84 

 zygomatic process. 38, 46 

 Squamosoids, 1 1 5 

 Squamous epidermis, 1 1 

 Squalma, 286, 310 

 Stapedial artery, 354, 356 

 Stapes, 41, 46, 49, 53, 64, 76, 80, 83, 85, 

 103, 406 

 foot plate. 41,80, 85 

 Stargazer, see Astroscopus 

 Statocyst, see otolith 

 Statodonti, 249 

 Stegotrachelus, 1 1 2 



external appearance, 32 

 STENSIO, 3, 137, 184, 186. 409 

 Stenson's duct, 56 

 Stereolepidelta, 112 



Stereospondylous vertebrae, 151, 155, 192 

 Sternohyoideus, 432, 436 

 Sternomastoideus, 432 



INDEX 



475 



