INDEX 



833 



Seal, bearded, pupils, 470, 472 



common, 502 

 fundus, PI. XIV 



harp, eye of, 447 



See also Phocida?, Pinnipedes. 

 Sea-lilies, 184 

 Sea-lion, 444, 445 



pujDils, 470 



See also Pinnipedes. 

 Sea-spiders, 217 



eyes of, 149, 217 

 Sea-squirts, 228 



See also Ascidia. 

 Sea-urchins, 184 



sensitivity of, 185 



See also Diadema. 

 Secretary bird. See Serpentarius. 

 Sedentaria, 190 

 Sedentary habit, degenerate eyes due to, 



722 

 Selache maximiis, 283 



extra-ocular muscles, 290 



pupils, 287 

 Selachians, 235, 278 



accommodation in, 647 



brain, 533 



central nervous sj'stem, 532 



ciliary ganglion, 501 



colour changes in, 95 

 control of, 558 

 vision in, 624 



electric organs in, 751 



eyes of, 279 if., 282 

 degenerate, 724 



labyrinths, 534 



luminous organs in, 741 



nocturnality of, 603 



palseocortex, 543 



pineal apparatus, 713, 714 



pupillary reactions, 612 

 consensual, 700 



refraction of, 638 



retina, pure-rod, 610 



secretory mechanism, 267 



summation, retinal, 660 



tapetum, retinal, 612 



threshold to light, absolute, 616 



vision of, 598 



visual field, binocular, 679 

 Seniotilus, colour preference in, 624 



hue-discrimination, 626 



threshold to light, difference, 617 



S.O.— VOL. I. 



Sensitivity to light, in insects, 584 

 in vertebrates, 602 

 absolute, 616 

 binocular, 680 

 dermal, 113 

 Sepia, 201 



colour changes in, 85, 92 

 conditioning of, 576 

 eyes of, 145, 202 

 reactions of, 528 

 vision of, 576, 577 

 Seps, transverse muscle in, 357 

 Sergestes prehensilis, photophore of, 746 

 Serpentarius cristatus, 413 



pecten, 413 

 Serranus, fovea, 309, 310 

 ocular movements, 693 

 cabrilla, 693 



accommodation of, 645 

 optic nerve, 310 

 Sertularia hj^droid, pigment in, 120 

 Sexual cycle in animals, 16 



control of, in crustaceans, 555 

 in insects, 556 

 vertebrates, 559 

 Shadow-reflex, 45, 572, 574 

 Shearwater. See Puffmus. 

 Sheep (Ovis), 446 

 angle gamma, 677 

 area centralis, 485 

 blood supjDly to eye, 499, 500 

 corpora nigra, 470 

 harderian gland, 494 

 lens capsule, 653 

 optic axis, 688 

 orbit, 498 



pectinate ligament, 464 

 photoperiodism in, 18 

 pupillary reactions, 472 

 retractor bulbi, 496 

 vitreous, 476 

 Shell-eyes, in Chiton, 196 

 Shock-reaction, 510 

 Shrew, 441 

 elephant, 441 

 otter, 441, 443 

 tree-, 441, 442 

 diurnality of, 604 

 lens, 474 

 true, 441 



ciliary region, 460, 467 



eyes of, 449 



retina, pure-rod, 610 



53 



