CHONDROSTEAN RETINA; HOLOSTEAN, TELEOST EYES 



573 



epithelial cells (which are of course homologous with rods and cones) ; 

 and similar vacuoles occur in some {Atnby stoma) ependymal cells (see 

 pp. 126-9 and Plate I). 



(C) HOLOSTEANS AND TeLEOSTS 



See also pages: 



5 visual consciousness 



44 Fig. 20e 



52 optic chiasma 



54 Fig. 22b 



55 Fig. 23c 



57-8, 60-1, 175-6, 216-7 visual cells 



59 Fig. 24e 



118 embryology 



127 Fig. 55d 



131 origin of lens muscle 



134-5, 137 Fig. 60, taxonomy 



145 habits 



146-53 photomechanical changes 



154, 157, 219-222, 228, 257 pupil 



157,231,373-5 rhodopsin 



158 Fig. 65 



160-1 pupil, iris muscles, optics 



164 energy economy 



174 eye size and shape, optics 



179 blind spot, optic nerve 



184-5, 187, 190, 303-5 Fig. 77b, area and 



fovea 

 191, 193-6, 200-2 yellow cornea and its 



value 



204, 405-7 eels 



210, 212-3, 384-405 bottom, cave, para- 

 sitic, deep-sea fishes 



230-241 eyeshine, tapetum 



235-6 argentea 



251, 254, 257, 260-3, 272-3 Fig. 98, 

 accommodation 



264-5 optics 



268 value of vitreous 



271, 380-1 Fig. 130, scleral ossicles 



277 ciliary muscle 



289-93, 320, 323-5, 331, 376-9 visual 

 angles and fields 



300-5 eye movements 



349 movement-perception 



362-5 stroboscopic vision 



364, 466-7, 472-90, 518-9, 521-2 color 

 vision 



369-76 ocular adaptations to water 



379-80 streamlining 



381-4, 418 lids 



414 comparison with whales 



431-6 amphibious vision 



450-4, 459-61 spectacles 



524-37 dermal color changes 



543-51 coloration of eye 



The only living holosteans are the bowfin or freshwater dogfish (Amia 

 caha) and the several species of gars (genus Lepisosteus). All are con- 

 fined to North American fresh waters. Amia is restricted to the United 

 States; Lepisosteus reaches south to Panama. Ancient holosteans were 

 the ancestors of the teleosts, which are cosmopolitan and greatly out- 

 number all other kinds of fishes put together. The eyes of the handful 

 of holosteans are best treated here together with those of the 20,000 

 species of teleosts; for, to all intents and purposes, the holostean eye 

 is a teleost eye. 



Holosteans — The extra-ocular muscles are normal in adults; certain 

 of them run through canals in the bones of the skull. In Amia larvae, 



