218 FISHES OF ILLINOIS 



membranes more or less completely joined to isthmus; branchiostegals about 

 6; pseudobranchiae concealed; gill-rakers very short; eyes in typical genera 

 very rudimentary and hidden under the skin, in such forms the body being 

 translucent and colorless; mouth rather large; lower jaw projecting; pre- 

 maxillaries scarcely protractile, forming entire margin of upper jaw; jaws 

 and palatines with bands of slender villiform teeth; stomach csecal, with one 

 or two pyloric appendages; air-bladder present; ovary single; some (and 

 probably all) of the species ovo viviparous; vent jugular. 



Fishes of small size, living in or about subterranean streams, 

 caves, and swamps of the southern United States. Four genera 

 and six species known, the majority being blind, with pale, 

 almost pigmentless, bodies, and with the eyes covered with thick 

 skin, inhabiting the cave region of southern Indiana, Kentucky, 

 and Missouri. The single species found in Illinois retains the 

 use of its eyes, and has the color of ordinary fishes. The group 

 Amblyopsidce is a very ancient one, as indicated by many points 

 in their anatomy. The forward position of the vent, though 

 not peculiar to these fishes, is found in only one other fresh- 

 water family (Aphredoderidce) , likewise a relict of a family all 

 but extinct. 



GENUS CHOLOGASTER AGASSIZ 



Eyes well developed; ventral fins wanting; body not translucent, the 

 skin having more or less pigment, and the color being much as in ordinary 

 fishes; pyloric caeca 4; character otherwise those of the family. Swamps of 

 the southern United States; a single species found in Illinois, at the mouths 

 of caves in Union and Pope counties. 



CHOLOGASTER PAPILLIFERUS FORBES 



SPRING CAVE-FISH 

 (PL., P. 220) 



Forbes, Amer. Nat., 1882, 2. 



J. & G., 325, 890 (papillifer); M. V., 83; J. & E., I, 704; F., 72; L., 22. 



Length 2.4 inches; elongate, little compressed, caudal peduncle deep; 

 head with rows of tactile papillae, as in the true blindfishes (Amblyopsis and 

 Typhlichthys)', depth 5 to 6; greatest width ^ of depth; depth caudal pe- 

 duncle 2 in its length. Color dark brown above, paler below; sides with 3 

 narrow longitudinal stripes, the upper and lower ones black, and the middle 

 one of the ground color or paler (not black, as in C. cornutus) ; caudal fin dark 

 brown, with several vertical rows of white specks running across the rays; 

 anterior portion of dorsal similar in color but paler. Head short, broad, and 

 exceedingly depressed, 4 in length; width of head 1.5 in its length; interorbital 



