532 



LAND ANIMALS 



Typhlichthys subterraneous and Amblyopsis spelaeus are also confined 

 to cave waters. Among the species of Chologaster, the coloration be- 

 comes paler from cornutus to agassizii; Typhlichthys is cream colored 

 and shows abundant pigmentation; Amblyopsis is colorless; the blood 

 and liver show through the body, and a little yellow pigment is re- 

 tained only at the fin bases and on the head. In other groups, the 

 coloration seems to be lost more rapidly. The brook amphipod (Gam- 

 marus pulex) in the caves in the Harz is colorless, and Planaria 



Fig. 134. — Degeneration of the eyes of American cave fishes: a-c, eyes of 

 Chologaster cornutus, C. papilliferus, and C. agassizii, X 40; d-f, vestigial eyes 

 of Amblyopsis spelaeus, Troglichthys rosae, and Typhlichthys subterraneus. L. 

 is the lens. X 200. After Eigenmann. 



montenegrina, widespread in the brooks of the Balkans, has a wholly 

 milk-white coloration in the Golubnjaka Cave in central Dalmatia. 16 

 Experiments show that color disappears under the influence of 

 darkness. Vire kept Gammarus fluviatilis in aquaria in the Paris 

 catacombs. They began to lose color after six months, and the pigment 

 finally disappeared entirely. On the other hand, the cave amphipod 

 Niphargus, maintained in the light, developed pigment spots in less 

 than two months, and Proteus in the light acquired a dark violet-brown 

 coloration. The ability to form pigment has thus been retained through 

 uncounted generations of subterranean life. Absolon 17 states that even 

 short exposure to light is deadly to a number of subterranean spring- 



