466 



THE EYE IN EVOLUTION 



and micro -anatomical methods api^lied by Troncoso and Castroviejo (1936) and 

 Troncoso (1937). Troncoso called the cleft the cilio-scleral sinus, but since it 

 does not sejaarate the ciliary body and the sclera but extends into the ciliary 

 body itself, ciliary cleft (or sinus) would seem a more appropriate name. 



The ciliary 2^rocesses vary considerably in their form, depending 

 on the number and arrangement of the zonular fibres, the development 



Figs. 598 and 599. — The Ciliary Processes of Placentals 

 (after Franz, 1911). 



Fig. 598.— Felis Ubyca. 



C cornea ; I, iris ; P, pectinate liga- 

 ment ; S, sclera. 



Fig. 599. — Eleplias maximus. 



C, ciliary processes ; /, iris ; O, orbi 

 cuius ciliaris ; S, ora serrata. 



of which depends on accommodative activity. ^ Three general types 

 exist (Figs. 598 and 599). 



1. In the lower orders as exemplified in the Rodents (rabbit), 

 the processes are thin and blade-like with deep valleys between ; many 

 of them extend far into the iris as is seen in the human embryo, 

 touching the lens anterior to the equator, so that the corona ciliaris is 

 in large part an iridic structure. The posterior chamber is thus exceed- 

 ingly small. 



2. In the Ungulates as exemplified in sheep, jjigs and cattle, the 

 processes are thick and club-like with shallow valleys and are confined 



^ I'lr the comparative anatomy see Wiirdinger (1886), Bayer (1892), Lauber 

 (1901 ■ ; . Virchow (1910), Franz (1912), Hess (1913), Beauvieux and Dupas (1926). 

 Troncc. !*)42), Wislocki (1952), Rohen (1953). 



