120 



BLIND \T,RTEBRATES AND THEIR EVES. 



Measurements of the Eyes of Cliologaster in Groups. 



[Treated alike.] 



Measurements of the Retina of Species of Chologaster. 



[Only averages from two to nine measurements are given in each case.] 



It is seen that the retina of agassizii differs from that of papiUiferus almost alto- 

 gether in the decrease of the thickness of the pigment epithelium. The retina of 

 cvrnitlits differs from that of agassizii in the reduction of the layers inside of the 

 pigment epithelium. 



TYPHLICHTHYS SU BTERRANEUS. 



The eye of Typhlichthys sublen-nnci/s has not heretofore been made the sub- 

 jci t <>l study. The following account is based on 3 specimens, 20, 25, and 45 mm. 

 long respectively, from a small cave in the town of Glasgow, Kentucky, and a 

 number <>l specimens of various sizes, the largest 54 mm., from Mammoth Cave, 

 Ki-ntuck These were all collected by myself in the early part of September, 1897. 



The rye ol this species is in general less degenerate than that of Amblyopsis. 

 The accessory structures are, on the other hand, much more degenerate than in 

 Amblyopsis. The eye can not be seen from the surface. The region of the eye 

 is, however, more conspicuously apparent than in Aniblvopxis on account of the 

 thinner ti ues of this smaller species through which the orbital fat-mass can be 

 seen. The eye can not be seen even in heads cleared with oil on account of 

 the almost total absence of pigment about the eye and its total absence in the 

 eve itself. 



