21S FISHES OF ILLINOIS 



rounded; no mesocoracoid; gill-membranes more or less completely 

 joined to isthmus; branchiostegals about 6; pseudobranchias concealed; 

 gill-rakers very short; eyes in typical genera very rudimentary and hid- 

 den under the skin, in such forms the body being translucent and color- 

 less; mouth rather large; lower jaw projecting; premaxillaries scarcely 

 protractile, forming entire margin of upper jaw; jaws and palatines with 

 bands of slender villiform teeth; stomach caecal, with one or two pyloric 

 appendages; air-bladder present; ovary single; some (and probably all) 

 of the species ovoviviparous ; 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 Amblyop- 

 sidce 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 (Aphredo- 

 derida), 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; characters 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 



(cave-fish) 



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 

 peduncle 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. cor- 

 nutus) ; 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 . S in its length ; interorbital space flat, 3 . 4 in head ; eyes 2 . 8 in 



