590 EMBRYOLOGY OF THE LOWER VERTEBRATES 



Serous membrane, 469 

 Serranus, segmentation, 21 

 Sheath, medullary, 85, 112 



of notoehord, chondrification, 293 



primitive, gray, 105, 110, 112 

 Shield, embryonic, 48 

 Siredon (Amblystoma, Axolotl), lens, 139 

 Skin, 69 

 Skull, 306, 341 

 Soma, 266 

 Somatopleure, 144 

 Somites, mesoblastic, 59 

 Sphenodon — 



pineal eye, 97, 99 



ribs, 305 



vertebrae, ossification, 338 



vertebral centra, 302 

 Spinal cord, 83 



ganglia, 121 

 Spinax — 



muscle-buds, 207 



occipital myotomes, 209 



visceral arch skeleton, 321 

 Spiracle, 158, 344 

 Spiral segmentation, 9 



valve of intestine, 183, 184, 185 

 Splanchnic mesoderm, 144 

 Splanchnocoele, 198 

 Splanchnopleure, 144 

 Spleen, 427 

 Spongioblasts, 84 

 Sternum, 305 

 Stomodaeum, 144 

 Subclavian artery, 405 

 Subgerminal cavity, 49 

 Subnotochordal rod, 290 

 Suprapericardial body, 178 

 Suprarenal, 282 

 Symbranchus — 



external form, 444 



opercular opening, 158 

 Symmetry of egg, 8, 11 

 Sympathetic, 124 

 Syncytium, yolk, 16, 22 



Tail, autotomy in Lizards, 33> 



evolutionary origin, 453 



form, 440 

 Technique of Embryology — 



Amphibia, 566 



Birds, 508 



Fishes, 558 



general, 573 

 Tectum opticum, 89 

 Teeth, 323 



succession, 327 

 Telencephalon, 95 

 Teleostei (ordinary Fishes) — 



air-bladder, 166, 167 



brain, 95, 96 



cement-organs, 182 



egg, 20 



falciform process, 140 



Teleostei (continued) — 



gastrulation, 46 



lepidotrichia, 347 



male genital duct, 281 



opisthonephros, 259 



ovary, 276, 277 



oviduct, 276, 278 



pancreas, 190 



practical hints, 564 



pronephros, 234 



segmentation, 19, 21, 22 



separation of yolk-sac, 464 



urinary bladder, 242 



viviparity, 479 

 Telolecithal, i 

 Terminal sinus, 527, 533 

 Testicular network, evolution, 279 

 Testis, 274 



Thalamencephalon. 87 

 Thalamus, 89 

 Thymus, 177 

 Thyroid, 175 



evolutionary origin, 176 

 Tongue, 150 

 Torpedo (Electric Ray) — 



buccal opening, 147 



fin rudiments, 445 



gastrulation, 45 



heart, 366 



mesoderm segments in head, 209 



muscle-buds, 208 



ostium tubae, 243 



pronephros, 237 



segmentation, 14, 15 



vertebral centra, 299 

 Trabeculae cranii, 307 

 Trachea, 161 

 Triton (Newt) — 



heart, origin, 360, 361 



larvae, 157 



opisthonephros, 252 



origin of mesoderm, 62 



rib, 304 



tongue, 150 



vertebral centra, 300 

 Trophonemata, 479 

 Tropibasic, 307 

 Tropidonotus (European Grass Snake)- 



origin of mesoderm, 64 

 Turbinals, 128 

 Tympanic cavity, 344 



membrane, 344 



Umbilical vein, 423 

 Ureter, 257 



Urodela, segmentation, 29 

 Utricle, 130 



Valvula cerebelli, 95 

 Vanellus, primitive streak, 53 

 Vasa efferentia, 272, 273, 279 

 Velar membrane, 145 

 Velum transversum, 90 



