CIIOLOGASTER 219 



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 papilla;; 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 a lin- 

 ing from the foot of a Mississippi River bluff, and from a cave on the 

 ( >hio River near Golconda, in Pope c< itinty. This species was origi- 

 nally described from material sent the senior author in 187° 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 be- 

 tween the true blindfishes of the caves (Amblyopsis and Typh- 

 lichthys) 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 ele- 

 ments 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 tins species have not been espe- 

 cially studied, although it is km >wn t< > 1 ie carnivorous. Dr. Shufelclt, 

 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, aGammarus which was 

 appn m chine, 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 tin fish is lurking under stones in the neighborhood of the out- 

 lei of its subterranean resort. 



