370 



THE EYE IN EVOLUTION 



Figs. 445 and 446. — The Chelonian Eye. 

 so. 



Fig. 445. — Diagram of a Chelonian eye. 



A, annular pad ; Ch, choroid ; CM, ciliary muscle ; ON, optic nerve ; 

 P, pectinate ligament ; S, scleral cartilage ; Sc, sclera ; SM, sphincter 

 muscle ; SO, scleral ossicles ; VS, ciliary venous sinus ; Z, zonule. 



Fig. 446. — Section through the eye of the tortoise, Testudo (Norman Ashton) 



leathery-skinned turtle, Dermochelys, Rochon-Duvigneaiid, 1943) 

 (Fig. 447). In aquatic forms, the iris has the same bright and varie- 

 gated colour as in the lizard — red, yellow, green and brown — and in 

 some ■ y])es is strij^ed in such a way that the pattern on the skin is 

 cont i v-rl over the iris as if for the purposes of camouflage (the terrapin, 

 Cle7n:; Mann, 1931 ; and particularly the i3ainted turtle, CAr^/'^ew?/^, 



