376 



THE EYE IN EVOLUTION 



The EYEBALL shows the main characteristics of the typical 

 reptihan eye described in hzards.^ The globe, however, is almost 

 spherical, little deformed by a corneo -scleral sulcus. The cornea is 

 thin ; the scleral cartilage reaches almost to the ora serrata and scleral 

 ossicles are absent. 



The ciliary body shows more than 100 tongue-shaped ciliary 

 processes^ which contact the lens at its equator ; the ciliary musculature 



Fig. 455. — The Crocodilian Eye. 



ap, annular pad ; c, cornea ; cp, attenuated tongue-shaped ciliary 

 processes ; i, iris ; I, lens ; o, ora serrata ; on, optic nerve ; s, scleral carti- 

 lage ; V, ciliary venous sinus ; z, position of zonule (from a drawing by 

 Rochon-Duvigneaud, Les Yeiix et la Vision des Vertebres, Masson et Cie). 



is represented by meridional elements only, the transversalis muscle 

 being absent ; while the angle of the anterior chamber forms a wide 

 cleft spanned by an unusually large pectinate ligament. In this 

 region the branched ciliary venous sinus, the analogue of the canal 

 of Schlemm, is wholly embedded in the sclera. The anterior surface 

 of the iris is covered by a thick layer of lipophores and guanine-bearing 

 iridocytes giving this structure a conspicuously bright lemon-yellow 

 sheen (Plate VIII). The pupil, contrary to its behaviour in Lacertilians 

 and C'helonians, is briskly I'eactive both to light and drugs (Johnson, 



1 p. 356. 



^ 110 ciliary proces.ses : Tiedemaiui, Oppel and Liposchitz, Xalurgeschichte der 

 A'ni'phibii ,:. Part 1. Heidelberg (1817). 



