G51 



INDEX. 



Third nerve, development of, 379 



Thymus gland, 627 



Thyroid gland, Petromyzon, 75 ; general 

 account of, 624 ; nature of, 625 ; de- 

 velopment of in Vertebrata, 626 



Tooth. See ' Teeth ' 



Tori semicirculares, 352 



Tornaria, 307 



Trabecule?, 466, 468 ; nature of, 468 



Trachea, 630 



Trematoda, excretory organs of, 561 



Triton alpestris, sexual larva of, 118 



Triton, development of limbs of, 509 ; 

 urinogenital organs of, 587 



Truncus arteriosus, 524; of Amphibia, 

 525 ; of Birds, 526 



Tunicata, development of mesoblast of, 

 243 ; test of, 326 ; eye of, 418 ; auditory 

 organ of, 436 ; olfactory organ of, 438 ; 

 generative duct of, 616 ; intestine of, 

 631 ; postanal gut of, 634 ; stomodseum 

 of, 639 



Turbellaria, excretory organs of, 561 



Tympanic annulus of Frog, 483 



Tympanic cavity, of Amphibia, 111 ; Chick, 

 149 ; Eabbit, 192 ; general development 

 of, 435 ; of Mammals, 485 



Tymjianic membrane, of Chick, 150 ; gene- 

 ral development of, 435 



Tympanohyal, 486 



Umbilical canal of Elasmobranchii, 45, 

 47, 48, 49 



Umbilical cord, 197 ; vessels of, 198 



Ungulata, placenta of, 208 



Urachus, 198, 599 



Ureters, of Elasmobranchii, 574 ; develop- 

 ment of, 596 



Urethra, 599 



Urinary bladder of Amphibia, 587 ; of 

 Amniota, 598 



Urinogenital organs, see Excretory organs. 



Urinogenital sinus of Petromyzon, 577 ; 

 of Sauropsida, 598 ; of Mammalia, 

 599 



Urochorda, development of, 8 



Uterus, development of, 598 ; of Marsu- 

 pials, 598 



Uterus masculinus, 598 



Utriculus, 427 



Uvea of iris, 403 



Vagus nerve, development of, 374, 376 ; 



intestinal branch of, 376 ; branch of to 



lateral line, 377 

 Valve, spiral, of Petromyzon, 79; Aci- 



penser, 91 ; general account of, 631 

 Valves, semilunar, 527 ; auriculo-ventri- 



cular, 528 

 Vasa efferentia, of Elasmobranchs, 574 ; 



of Amphibia, 586; general origin of, 



597 

 Vascular system, of Amphioxus, 7 ; Petro- 



myzon, 80 ; Lepidosteus, 96 ; general 

 development of, 519 



Vas deferens, of Elasmobranchii, 575 ; of 

 Amniota, 596 



Vein, sub-intestinal of Petromyzon, 80 ; 

 Acipenser, 91 ; Lepidosteus, 96 



Velum of Petromyzon, 74 



Vena cava inferior, development of, 538 



Venous system of Petromyzon, 80 ; gene^ 

 ral development of, 535 ; of Fishes, 535 ; 

 of Amphibia and Amniota, 538 ; of 

 Beptilia, 539 ; of Ophidia, 539 j of Aves, 

 641 ; of Mammalia, 545 



Ventricle, fourth, of Chick, 146 ; history of, 

 349 



Ventricle, lateral, 360, 362 ; fifth, 365 



Ventricle, third, of Chick, 145 



Vertebral bodies, of Chick, 151 



Vertebral column, development of, 449, 

 453 ; epichordal and perichordal de- 

 velopment of in Amphibia, 458 



VespertilionidfB, early development of, 179 



Vieussens, valve of, 351 



Villi, placental, of zona radiata, 195 ; sub- 

 zonal membrane, 195 ; chorion, 197 ; 

 Man, 204 ; comparative account of, 215 ; 

 of young human ovum, 221, 225 



Visceral arches, Amphioxus, 6 ; Elasmo- 

 branchii, 47—50 ; Teleostei, 62 ; Aci- 

 penser, 87; Lepidosteus, 96; Amphibia, 

 109, 110; Chick, 147; Eabbit, 191; 

 prsBoral, 470; relation of to head ca- 

 vities, 471 ; disappearance of posterior, 

 472 ; dental plates of in Teleostei, 473 



Visual organs, evolution of, 387 



Vitelline arteries, of Chick, 162 



Vitelline veins, of Chick, 162 



Vitreous humour, of Ammocoetes, 81 j 

 general development of, 407; blood- 

 vessels of in Mammals, 414; meso- 

 blastic ingrowth in Mammals, 414 



Vomer, 488 



White matter, of spinal cord, 342; of 



brain, 348 

 "Wolffian body, see ' Mesonephros ' 

 Wolffian duct, first appearance of in 



Chick, 152; general account of, 569; 



of Elasmobranchs, 571 ; of Ganoids, 580 ; 



of Amphibia, 585; of Amniota, 5^8; 



atrophy of in Amniota, 597 

 Wolffian ridge, 163 



Yolk blastopore, of Elasmobranchii, 52 



Yolk, folding off of embryo from, in 

 Elasmobranchii, 45 ; in Teleostei, 62 ; 

 Acipenser, 87 ; Chick, 139, 141 



Yolk nuclei, of Elasmobranchii, 34, 44; 

 Teleostei, 56, 61 



Yolk, of Elasmobranchii, 33; Teleostei, 

 55; Petromyzon, 79; Acipenser, 90; 

 Amphibia, 101, 107; Chick, 121; in- 

 fluence of on formation of layers, 230; 



