176 



BLIND VERTEBRATES AND THEIR EYES. 



without an intervening stage like that of cornutus, and the pigment layer has lost 

 its pigment, whereas in Amblyopsis it was retained. 



The reduction in size from the normal fish eye went hand in hand with the 



Fig. 66. Diagrams of Eyes of all Species of Amblyopddie and Typhlomolge, d.e,g h, and i drawn under same 

 magnification, (a) Clwlogast:r cornutus, (b) Clwlogasler papillijerus, (c) Chologaster agassizii, drawn 

 to scale; (rf) Retina of Chologaster cornulus; (c) Retina of Chologaster papillijerus; (/) Eye of Typhlo- 

 molge under lower magnification than d-j\ (g) Eye of Typhlichlhys subterraneus ; (h) Eye of Amblyopsis 

 speleeus; (») Eye of Troglichthys rosa. 



simplification of the retina. There was at first chiefly a reduction in the number 

 of many times duplicated parts. Even after the condition in Chologaster papillij- 

 erus was reached the degeneration in the histological condition of the elements did 

 not keep pace with the reduction in number (vide the eye of cornutus). The 



