HOLOSTEAN RETINA; TELEOST EYE 577 



grenadiers etc.) — which lack true spines (though the cyprinodonts, pos- 

 sibly also the anacanthines, are to be suspected of having once had them) . 

 Figure 169 shows all of the principal morphological features which 

 teleost eyes ever present, though of course not always with these partic- 

 ular sizes, shapes, and orientations. Each of these features may be present 



scleral cortilage 



chorioid 

 'gland' 



epichorioidal lymph space 



cornea: 



autochlhon- 

 'ous layer 



scleral 

 layer 



dermal 

 , J ^ " layer 



lent/form 

 body 



orgenlea of/ 

 chorioid 



argentea 

 of iris 



annular 

 ligament 



conjunctiva 

 tensor chorioidece 



Fig. 169 — Diagrammatic vertical section of typical teleost eye. 



Certain of the structures may be lacking in a particular species (see text). A falciform 

 process and a system of hyaloid vessels are never simultaneously present; and where the 

 falciform process is lacking, the lentiform body is absent also. The argentea, shown in 

 black, actually of course contains reflective, not absorptive, pigment. 



or absent, usually independently of any others, from family to family 

 or even within one family, without much regard to the families' taxo- 

 nomic positions. Particularly, there is no feature which may not be 

 present (or absent) in both malacopterygian and acanthopterygian 



