" Vascular " tissue of Echinodermata, 



see Lacunar tissue 

 Vegetative phase, 31 

 Vegetative pole, 248 

 Vein, Abdominal, 519; Afferent 



branchial, 506; Branchial, 519; 



Efferent branchial, 507; Genital, 



519; Ink sac, 519; Longitudinal, 



of kidney, 507; Pulmonary, 482. 



See also Circulus venosus, Sinuses, 



Vena cava 

 Velella, 145; 147 

 Veliger, 474 

 Velum, of Medusae, 135, 154; of 



Rotifera, 211 ; of Veliger larva, 474 

 Vena cava, 518 



Ventral, see Dorsal and ventral 

 Ventral blood vessel, of Balanoglossus, 



588; of Chaetopoda, 230, 240; of 



Rhynchobdellidae, 265 

 Ventral "blood vessels" of Echino- 

 dermata, 553, 567, 575 

 Ventral cirrus, 23 1 

 Ventral mesenteries, of Alcyonaria, 



159; of Polychaeta, 251 

 Ventral midline of Nematoda, 214 

 Ventral plate of trochosphere, 250 

 Ventral plates of Ophiuroidea, 562 

 Ventral siphon, 501 

 Ventral tube of Collembola, 408 

 Ventricle, see Heart 

 Venus' Girdle, see Cestus Veneris 

 Vermes, 174 



Vertebrae of Ophiuroidea, 562 

 Vertebrata, i, 2, 583, 584, 585 

 Vesiculae seminales, see Generative 



organs 

 Vesicular nuclei, 19 

 Vespa, 433 

 V. crabro, 431 

 Vestibulata, 102 



Vestibule, 15 ; 97, See also Gullet 

 Vibracula, 533 

 Visceral clefts, 583 

 Visceral hump, 471, 472, 477, 481, 



482, 490, 5i5> 525 

 Visceral mass, 344 

 Visceral nerves, see Sympathetic 



system 

 Vitellarium, of Platyhelminthes, 185 ; 



of Rotifera, 212 

 Vitelline ducts, 185 



INDEX 645 



Vitrellae, 277 



Volvocina, 49; 38, 44; reduction 



division of, 23, 32; syngamy of, 



26, 40 

 Volvox, 52 ; 27, 33,35, 39, 4°, 54, 55 

 V. aureus, 53 ; 54," 55 

 V.globator, 54; 55 

 Vorticella, 104; 4, 5, 16, 29, 97 



Waldheimia, 537 ; 538, 540, 542 

 Water pore of Echinodermata, 552 

 Water vascular ring, see Water 



vascular system 

 Water vascular system, 550; 551, 



552, 560, 564, 569, 580 

 Wings, 385; 403 

 Wire worm, see lulus terrestris 

 W^orkers, of Isoptera, 412; 413, 414; 



of Wasps, 434 



Xanthophyll, 41 

 Xanthoplasts, 41 

 Xenocoeloma, 337 

 Xenopsylla cheopis, 442 

 Xestobium rufovillosum, 431 

 Xiphosura, 454 

 Xylophaga, 511 



Yellow cells of Chaetopoda*, 229, 



240 

 "Yellow cells ", Symbiotic, see Zoo- 



xanthellae 

 Yolk gland, see Vitellarium 

 Young, see Life history 

 Yungia, 190 



Zoaea larva, 316; 349, 351,361,370, 

 372, 372, 373 



Zoantharia, 163 



Zones of fission, 259 



Zoochlorellae, 43 



Zooecium, 530 



Zooids,of Coelenterata,seeHydranth, 

 Polyp ; of Polyzoa, see Polypide ; of 

 Protozoa, 4 ; 6 ; of Rhabdopleura, 

 590; of Tunicata, 599; of Volvo- 

 cina, 6, 51-4 



Zoomastigina, 54; 40, 56 



Zooxanthellae, 43 ; 36, 46, 75, 76 



Zygoptera, 417 



Zygote, 31; 32, 40, 48, 52, 78, 82, 

 83, 85, 86, 88, 89, 90, 93, 100, 108 



