692 



INVERTEBEATA 



Veatral cell-family in segmenting egg of 



Ascaris megalocephala, 440 

 Ventral ciliated epaulettes, formation of, in 



larva of Echinus esculentus, 511 

 Ventral ganglion, formation of, in Sagitla 



bipwnctata, 432 

 Ventral nerve-cord, formation of, in Crio- 



drUus lacuum, 158 ; in Nephdis, 162 ; in 



Peripatus capensis, 174 ; in Polygordius 



appendiculatus, 147 

 Ventral organs, formation of, in Peripatus 



capensis, 174 

 Ventral plate in the embryo oiAgelena, 224 ; 



in embryo of Unio^ 351 ^ 



Ventral retractor muscles, formation of, in 



larva of Dreissensia, 341 

 Ventral shield in embryo of Astacus, 186 

 Ventral sinus, formation of, in Nephdis, 163 

 Ventricle of heart, formation of, in Cydas, 



350 ; in Loligo, 362 

 Ventro-lateral chamber of Urticina crassi- 



cwnis, 80 

 Vertebra, formation of, in Amphiura squa- 



Vertebr'ata, 29, 162, 668, 569, 584, 585, 

 586, 605, 606, 608, 625, 636, 646, 662 



Vesicula seminalis of Ascaris megalocephala, 

 438 



Vestibule, formation of, in larva of Antedon 

 rosacea, 557 ; in larva of PediceUiiia, 400 



Vibratile cleft, formation of, in Cyphonautes 

 larva, 390 



Vibratile plume, formation of,in Cyphonautes 

 larva, 391 



Visceral ganglion, formation of, in larva of 

 simple Ascidian, 622 ; in Dreissensia, 

 342 ; in Loligo, 358 ; in Paludina, 315 



Visceral hump, formation of, in Loligo, 

 361 ; in Patella, 300 



Visceral muscles, formation of, in Criodrilus, 

 158 ; in Donacia, 256 ; in Polygordius 

 apipendiculatus, 147 



Visual rods, of Cephalopod eye, formation 

 of, 368 ; of ocelli of Dytiscus, 273, 274 



Vitellarium of Callidina russeola, 424 



Vitelligenous cells of Platyhelniinthes, 102 



Vitelline membrane, definition of, 3 ; forma- 

 tion of, 9, 17 ; in egg of Amphioxus, 

 587 ; in unfertilized eggs of Echinoidea, 

 524 



Volvox, 660 ; compared with blastula, 51 



Water-tubes of larva of Asterias, 466 



Water-vascular system of Echinodermata, 

 see Hydrocoele "" 



Wheel-organ, formation of, in Amphitisifas 

 laiiceolatus, 604 ; in Ocdlidina russeola, 426 



Wheels in larva ol Syuapta digitata, 535 



White bodies, formation of, in Loligo, 361 



Wings of Doryphora, development of, 271, 

 273 



W ings, rudiments of, in larva of Galerucella 

 ulmi, 268 



Wing-sac of Buprestidae, 277 ; of Ceram- 

 bycidae, 277; of • Culioidae, 278; in 

 Doryphora, 271 ; in Inseota, various types 

 of, 277-279 ; of Lepidoptera, 278 ; of 

 Muscidae, 278, 279 ; of Scarabaeidae, 

 277 ; of Tipulidae, 278 



Worm-like larva of Ophiura hrevispina, 562 



Xiphosura, 221 



Yoldia, l>irva of, 349, 369 



Yolk, influence of, on segmentation of egg, and 



on the formation of layers in the embryo, 



26, 657 

 Yolk -cells, formation of, in embryo of 



Donacia, 247 ; in embryo of Lepist^ia, 



264 ; in embryo of Pyrosoma, 633 ; in 



Scolopendra, 282 

 Yolk-lobe in egg of Dentalium, 326. (See 



also Polar lobe.) 

 Yolk-membrane, formation of, in egg of 



Sepia, 355 

 Yolk-nucleus, definition of, 3 ; of egg of 



Cynthia partita, 610 

 Yolk-sac, development of, in Helix, 369 ; 



in Loligo, 360 

 Yungia, 161 ; development of larva of, 112- 



115 



Zoaea larva, 217 ; description of, 208 ; in- 

 terpretation of, 210-212 ; of Anomura, 

 210, 213 ; of Brachyura, 210, 213 ; of 

 Caridea, 209, 213 ; of Buphausidaoea, 

 208, 212 ; of Penaeidea, 209, 212 

 Zoantharia, 53 ; development of, 76-86 

 Zoanthella larva of Zoanthidae, 85 

 Zoanthidae, 53 ; larvae of, 85 

 Zoanthina larva of Cereanthidae, 85 

 Zocecium, formation of, in Polyzoa Ecto- 



procta, 396, 397 

 Zygonema, definition of, 4 

 Zygote, definition of, 2 

 Zygote nucleiis, definition of, 9 

 1 Zygotene thread, definition of, 4 



END OF VOL. 1 



Printed by R, & R. Clakk, LlMiTEn, Edinburgh, 



