MAMMALS 



467 



to the ciliary region ; their anterior ends form a soHcl wall not encroach- 

 ing u23on the iris so that the jjosterior chamber is deep. The apices of 

 the processes, however, touch the lens. 



3. In Carnivora, as exemi^lifiecl in the cat. dog, and lion, the 

 ciliary processes are of two tyjies — Iviiife-like, tall, major processes 

 between every jDair of wliicli lies a small minor process ; none of them 

 reaches the lens. In the Primates the general arrangement is similar 

 but the main ciliary processes are stouter and more rounded and 

 several stumpy minor folds (plicte ciliares) lie between the main 

 processes. 



Fig. 600. — The Iris of the Fcetal Guinea-pig. 



Xote the circulus arteriosus iridis major faintly outlined in the nasal and 

 temporal parts and the vessels of the pupillary membrane spanning the 

 ]3upil (from a slit-lamp drawing by Ida INIann). 



4. Finally, the ciliary processes are absent in the shrews 

 (Soricidse).i 



Curious nervous structures have been described in the ciUary body of certain 

 Cetaceans in the regiDU of the angle of the anterior chamber which may perhaps 

 be CILIAKY RECEPTOR ORGANS. In the beaked whale, Hyperoodon, Putter (1912) 

 found elongated nervous structures which appeared to be associated with the 

 ciliary nerves, and in the hump-back whale, Megaptera, Rochon-Duvigneaud 

 (1943) described oval bodies isolated or lying in groups, resembling pacchionian 

 coipuscles or the corpuscles of Herbst in the bill of the duck. Their function is 

 enigmatic, but it has been suggested that they are sensory pressure-organs of 

 value to the animal when it dives. This may be possible in view of the 

 " corpuscles " described by Kurus (1955) in the ciliary body of man which 

 conceivably may act as receiptors to changes in the intra-ocular pressure. 



1 It will be remembered they are also absent in Fishes (except Selachians), 

 Sphenodon, lizards and snakes. 



