840 



INDEX 



Typhlomolge, degenerate eyes in, 728 

 Typhlonarke, degenerate eyes of, 279, 724 

 Typhlonectes, eyes of, 730 

 Typhlonus, degenerate eyes of, 724 

 Typhloperipatus, degenerate eyes in, 724 

 Typhlopidse, 383 



eyes of, 731 

 Typhlops, eye of, 731 

 Typhlotriton, degenerate eyes in, 728 



U 



Uca, colour changes in, 95 

 metabolic rhythm in, 16 

 retinal pigment migration in, 19, 20 

 Ultra-violet light, visibility of, in insects, 

 585, 587 

 in stickleback, 619 

 Umbra, colour vision in, 625 



threshold to light, difference, 617 

 Umbraculum, pupillary, 470, 612 

 Ungulates, 446 



accommodation lacking in, 653 

 area centralis, 485 

 arhythmicity of, 604 

 blood supply to eye, 500 

 ciliary muscle, 461 



processes, 466 



region, 461, 462 

 circle of Hovius, 472 

 colour blindness of, 634 

 cornea, 453 

 corpora nigra, 469 

 Moll's glands, 492 

 nictitating membrane, 493, 496 

 ocular movements of, 696 

 optic axis, 688 



disc, 486 

 orbit, 498 



pectinate ligament, 464 

 pupils, 471 



reactions of, 472 

 ramp -retina, 643 

 refraction, 639 

 retinal vascularization, 479 

 retractor bulbi, 495 

 spatial judgments, 704 

 tapetum fibrosum, 457, 609 

 vision of, 601 

 visual acuity of, 664 



field, binocular, 689 

 uniocular, 672 



I Ungulates, zonular fibres, 475 

 See also various genera. 

 Uniocular vision, 697 



visual fields, 669 

 Uranoscopus, pupil, 329 



visual field, binocular, 680 

 Urinary output, diurnal rhythm in, 13 

 Urochordates. See Tunicates, 

 Urodeles, 334 



accommodation in, 648 

 colour vision in, 628 

 eyes of, MQff., PL IV 



degenerate, 726 

 lateral lines, 534 

 migration of retinal pigment, 614 



of visual cells, 616 

 ocular movements in, 694 

 pineal organ, 714 

 refraction of, 639 

 vision of, 599 

 Uromacer, visual field, binocular, 684 

 Ursidae. See Bears. 

 Uveal tract, characteristics in 

 amphibians, 335 

 birds, 404 

 chelonians, 370 

 coelacanth, 315 

 dipnoans, 313 

 fishes, 277 

 lacertilians, 356 

 lamprey, 266 

 marsupials, 438 

 placentals, 457 

 selachians, 281 

 snakes, 385 

 Sphenodon, 380 

 teleosts, 296 

 See also Choroid, Ciliary region. Iris. 



V 



Vampire bat, 443 

 Vanadis, eye of, 143 

 Vanessa, 170 



colour vision in, 587 



scototaxis in, 56, 60 



vision of, 585 

 Varanus, conus, 362 



eye of, 354 



orbit, 368 



visual field, binocular, 682 

 bengalensis, iris furrow, 337 



