Summary: 208; in Chick, 437, 470; in Pig, 632, 634 thyrinoidea, in Pig, 620, 623, 624 thyroid, in Frog, 209; in Chick, 437, 471; in Pig, 632, 634 cartilage, in Frog, 241, 253, 254; in Chick, 440 trabeculae of ear capsule, in Pig, 618, 619 trabeculae of metanephros, in Chick, 468 trabeculae of spleen, in Pig, 633 trachelo-mesenteric vein, in Frog, 229, 230 transitory connective tissue, in aChick, 302; in Mammal, 510 tubular glands, in Pig, 621 vagina, in Mammal, 498, 507, 549, 550; in Pig, 656, 656 van der Stricht, O., 545 variations in early development, in Humans, 538; in Mammals, 531; in Opossums, 532 velum transversum, in Chick, 416, 474; in Pig, 568, 579, 615 venous network, in Frog, 212 venous sinus, in Pig, 618, 620 vermis, in Pig, 572 vertebral columns, in Pig, 650 vii, G. F., 163 Viesel, \., 305 vitelline blood (umbilical) veins, in Pia, 616 vitelline sinus, in Pig, 616 vitelline veins in Man, 568, 616 vocal cords, in Frog, 174; in Pig, 616 voice organs, in Pig, 616, 617, 625 volkmann's canals, in Chick, 439, 440; in Pig, 656 vosorious teeth, in Pig, 674 wolkoff’s test, 503 Wolffian duct, in Mammal, 493-495; in Pig, 561, 605, 636, 645 Wolffian tubules, in Pig, 561, 605, 605, 606, 636; in Chick, 339, 339; in Frog, 231 womb, in Mammal, 501; in Pig, 646, 647, 648, 653; in Dog, 647, 648, 648 yolk, 5, in Amphioxus, 79, 96, 215; in Frog, 108, 238; in Chick, 275, 305; in Mammal, 515 Ibos, 528; in Pig, 535, 537, 667 yolk sac, 9, in Amphioxus, 79, 92; in Frog, 238, 239; in Chick, 262, 267, 272, 272, 273, 464, 527; in Mammal, 509, 530, 531, 532, 533, 537, 546, 547, 548, 550; in Pig, 528, 529, 535, 537, 538, 540, 550; in Marsupials, 532; in Primates, 548, 549; in Monotremes, 531, 532, 533 y.s, Pig, 60, 61, yolk-sac area, in Chick, 361, 364; in Mammal, 512, 513 Y L, P 1g a676 yolk-sac cavity, in Chick, 361; in Mammal, 513, 512, 513, 513 y.s, in Pil, 53, 61 zonuler pellucid, in Mammal, 517 zone pellucida, in Frog, 107, 238; in Chick, 262, 272; in Mammal, 515, 515, 515; in Dog, 515 zymogen granules, in Pig, 621, 623, 624-630.