LAMPREYS AND FISHES OF INDIANA. 171 



Family SILURID.E. 

 THE CAT-FISHES. 



Maxillary bones rudimentary, found at the base of the lateral barbels. 

 Margin of the upper jaw formed by the premaxillaries. Two or more 

 pairs of barbels. In all our species the rayed dorsal is present and pre- 

 ceded by a spine ; there is an adipose fin present ; and the pectorals are 

 preceded by a stout spine. All our Indiana species are included under 

 the following four genera : 



A. Supraoccipital bone not reaching back to insertion of dorsal spine, 

 leaving in the middle line an interval filled Avith soft tissues. 

 a. Head broad and flat. Ventral rays, nine. Supraoccipital bone 

 not extending backward beyond a line joining the upper 

 ends of the gill-openings, 

 b. Adipose fins not free behind, running into the caudal; 

 branchiostegals, nine on each side. Xoturus, p. 171. 

 bb. Adipose fin free behind ; branchiostegals twelve on each 

 side. Leptops, p 175. 



aa. Head not so broad and flat. Ventral rays, eight. Supraoc- 

 cipital extending further back than the gill-slits. 



Ameiurus, p. 176. 



AA. Supraoccipital bone reaching back to insertion of the dorsal spine ; 



no soft interval. Tail forked. Ictalurus, p. 180. 



Genus NOTURUS Rafinesque. 



Body elongated, compressed behind, depressed in front of the dorsal 

 fin. Head broad and flat. Supraocciptal not reaching backward be- 

 yond a line joining tbe upper ends of the giil-slits, and not reaching the 

 base of the dorsal fin. Caudal rounded and inserted on a rounded base. 

 Dorsal not free behind, but running into the anal. Ventral rays, nine ; 

 branchiostegals, nine. 



Most of the species of Noturits are small, the largest not exceeding a 

 foot in length. They are of no importance economically. In tbe axil 

 of the pectoral fin is fi)uud a poison-pore, out of which. Cope says, may 

 be drawn a long gelatinous style, which is branched at the inner end. 



ANALYSIS OF THE SPECIES. 



A. Premaxillary band of teeth not narrowing to a point behind, but 

 ceasing abruptly. 

 a. Upper jaw projecting beyond the lower. 



b. Pectoral spines with the teeth on the hinder border 

 stronger than those in front. eleutherus, p. 172. 



