CHOLOGASTER 219 



space flat, 3.4 in head; eyes 2.8 in head, mostly on its upper surface; nose 

 broadly rounded, 3.5; mouth rather large, maxillary not reaching eye; lower 

 jaw projecting; sides and top of head with numerous mostly short and broken 

 and chiefly single rows of small sensory papillae; a prominent double row on 

 outside of each lower jaw, sunk in a groove extending from back to front of 

 mandible, and within this a parallel irregular row of smaller papillae on the 

 lower surface of the jaw; especially conspicuous papillae about the nostrils; 

 the latter conspicuous, tubular, projecting forward, with expanded openings. 

 Dorsal and anal fins thick and fleshy, their height about equal to their length; 

 developed dorsal rays 6, the fin inserted behind the middle of the body and 

 slightly in front of the anal; developed anal rays 5; caudal broadly rounded; 

 ventrals wanting; pectorals 1.7 in head. Scales very small, cycloid, covered 

 with thick skin. 



Known at present only from a cave spring in Union county 

 coming from the foot of a Mississippi River bluff, and from a 

 cave on the Ohio River near Golconda, in Pope county. This 

 species was originally described from material sent the senior 

 author in 1879 and again in 1881 by F. S. Earle, of Cobden, 111., 

 and specimens have since been repeatedly taken from the Union 

 county spring by various assistants of the State Laboratory. 

 The occurrence of the species in Pope county was reported to 

 me by Dr. Meek in 1908. 



Especial interest attaches to this little fish as intermediate 

 between the true blindfishes of the caves (Amblyopsis and 

 Typhlichthyus) and earlier described species of Chologaster. 

 The sensory structures of C. papilliferus correspond in character 

 to its situation as a partially subterranean species. Studies 

 recently made by Dr. Eigenmann show that the optic nerve 

 and all of the important elements of the eye are present, but 

 that the choroid is very thin and its pigment scanty, and that 

 the retina is much degenerated. 



The food and feeding habits of this species have not been 

 especially studied, although it is known to be carnivorous. Dr. 

 Shufeldt, quoting a note from Eigenmann, says that it detects 

 its prey by its cutaneous sense-organs and not by its eyes, 

 illustrating this statement by Eigenmann's observation of the 

 behavior of a fish in capturing, by an instantaneous movement, 

 a Gammarus which was approaching it from behind and below, 

 where it could not have been seen by its captor. This does not, 

 however, preclude the usefulness under other conditions of such 

 eyesight as it has retained, especially when the fish is lurking 

 under stones in the neighborhood of the outlet of its subterra- 

 nean resort. 



