358 



THE EYE IN EVOLUTION 



Figs. 423 and 424. — The Ciliary Region of the Lacertilian Eye. 



Fig. 423.— Tho lizard, Tupiiuimbis. 



G, scleral cartilage ; il/, ciliaiy muscle ; 0, scleral ossicles ; P, jDectinate 

 ligament ; S, ciliary venous sinus ; 2', tenacular ligament (after Franz). 



Fig. 424.— The skink. 



M , ciliary muscle ; O, scleral ossicles ; T', ciliary ^'enous sinus ( X 60) 



(Norman Ashton). 



Iguana tuberculata 



containing iridocytes (Plate V).i The vascular arrangements resemble 

 those of the salamander ; the two feeding arteries enter peripherally 

 below and to the temporal side and run circnmferentially but, in con- 

 tradistinction to the arrangement in amphibian eyes, the veins lie 

 superficially forming a plexus of radial vessels which are usually 

 conspicuous ; the cajiillary zone is of varying width but is often con- 



^ The irides of many lizards compare in their remarkable brilliance with those of 



nrie parrots. In the green lizard, Lncertn viridis, they are of brightly speckled gold ; in 



■■!n(A tuberculata they show an exceedingly delicate festooned pattern of gold and 



b ■; fibres ; in the geckos, a striped pattern of dark brown in a light yellow-ochre, 



g! -h or grey background ; and so on. 



