SILURID^E. CX. 333 



forwards, the front steeply elevated, the body thick 

 across the "shoulders," rather rapidly narrowed behind; 

 anal fin short and deep, of 18 or 20 rays, its base nearly 

 five in length, the color of the rays forming a sharp con- 

 trast with that of the membranes; upper jaw scarcely 

 longest; size small; color almost black. Mississippi 

 Valley, abundant. (A. catulus, obesus, confinis, etc., of 

 authors.) 



ff. Head very broad, the slope from snout to base of dorsal quite 

 uneven, there being a more or less decided angle at the 

 occiput. 



12. A. xanthocephalus, (Raf.) Gill. YELLOW-HEADED 

 CAT. Head about as broad as long, its length 4 in that 

 of body; dorsal nearer adipose fin than snout; anal fin 

 short, its base less than one-fifth the length of the body, 

 its rays usually 19; body stout and short; mouth very 

 broad; colors pale, chiefly yellowish; size small. Ohio 

 Valley, abundant; resembles A. natalis cupreus, but has 

 a much smaller anal. 



ee. Body very elongate, slender, the head flattish and broad above. 



13. A. platycephalus, (Grd.) Gill. FLAT -HEADED 

 CAT. Form slender, elongate, approaching that of Pelo- 

 dichthyS) the depth being 4 to 6 times in length of body; 

 head broad and flat, nearly as wide as long; anal fin 

 with 20 to 22 rays; the base of the fin 4 to 5 in body; 

 jaws equal; branchiostegals 11; mouth very wide; dor- 

 sal spine nearer snout than adipose fin; coloration some- 

 what marmorate; a blackish horizontal bar at base of 

 dorsal. Southern Rivers; approaches A. brunneus* but 

 less elongate, and with a different mouth. 



dd. Eyes rudimentary, concealed under the skin; blind cave 

 species. (Gromas, Cope.) 



14. A. nigrilabris, (Cope) Gill & Jor. CAVE CAT FISH. 



