INDEX AND GLOSSARY 



785 



wrasses: Labrids, q.v. 

 Wunder, 61, 176, 236 

 Wundt, 321 

 Wychgram, 648 



xantholeucophores, 526*, 595 

 xanthophores, 526* 



xanthophyll: a carotenoid pigment, q.v. 

 Xantusia (reptile: night-lizard; see also 

 next entry) 

 ciliary muscle in, 624 

 conus papillaris in, 625 

 dermal color changes in, 541 

 pupil of, 220 

 trace of fovea in, 625 

 visual cells of, 62, 78, 168, 200, 203, 

 626-627 

 rhodopsin lacking in, 78 

 XantusiidcE (reptiles: a lizard family; see 

 also Xantusia) 

 ciliary muscle in, 624 

 contrasted with snakes, 634 

 habits of, 200, 458 

 loss of fovea by, 621 

 oil-droplets in, 200 

 possible color vision of, 520 

 pupil in, 220 

 spectacles of, 450 

 trace of fovea in, 625 

 Xenarthra (order of mammals; most 'eden- 

 tates' : sloths, armadillos, and ant- 

 bears) 

 optic axes of, 297 

 retina of 



avascularity of, 684 

 lack (?) of cones in, 685 

 size of eye in, 677 

 taxonomic position of, 676 

 Xenopeltis (reptile: monotype of a snake 

 family intermediate between Boids 

 and Colubridse) 

 habits of, 201, 450 

 pupil of, 220 

 retina of, 636-637 

 spectacle of, 450 

 Xenopus (amphibian: dagger-frog) 

 dermal color changes in, 535 



rhythmic, 538 

 lower lid of, 593 

 permanently aquatic habit of, 368 



Xiphias (teleost: swordfish) 

 coloration and habits of, 526 

 scleral ossicles of, 271, 381 



Yerkes, 484, 491, 510 

 Young, 524 

 Young, J. Z., 537-538 

 Young, T., 88-89 



-Helmholtz theory of color vision, 75, 

 89*, 98, 101, 338, 513 



Z.aglossus (mammal: an echidna), 663*; 



ocular structure in, 664-671 

 Z.amenis (reptile: a colubrid snake), 

 binocular field of, 293-294 

 Z.aocys (reptile: a colubrid snake), 



binocular field of, 294 

 Zapfensubstanz, 100*, 101-103, 495 

 zebra grass-parakeet, Australian: 



Melopsittacus, q.v. 

 Zenion (deep-sea teleost), huge eye of, 



395, 400,402 

 Zenkerella (mammal: a flightless anomal- 

 urid rodent) 

 diurnality of, 227 

 pupil of, 221 

 Zinn, zonule of (see zonule) 

 Ziphiidae mammals: beaked whales), 412 

 Zolotnitzky, 473, 480 

 zonule, 19* 



as check-ligament, 268, 285, 683 

 development of, 115, 117 



TAXONOMICALLY: 



lampreys (lacking), 259 



elasmobranchs, 260, 268, 372, 429, 564, 



teleosts, 261 [567 



amphibians, 266-267, 596, 602 



chelonians, 609 



Sphenodon, 618-619, 624 



lizards, 624, 646 



snakes, 628-631 



birds, 645-646 



monotremes, 667, 669 



placentals, 681-683 

 man, 7, 19, 683 

 Zonurus (reptile: a zonurid lizard) 



eye-movements of, 306 



visual fields of, 294 

 Zygixna: Sphyrna, q.v. 



