SILURID^. 71 



followiug synopsis. A Chinese species, Pimelodus cantonensis, referred 

 by Dr. Giintber to Amiurus, is excluded, as its real position is perhaps 

 uncertain. The species are most abundant in the Mississippi Valley 

 and Great Lake Region. Some of them occur in all our waters east of 

 the Eocky Mountains, but as yet none are known from the Pacilic 

 Slope. 



ANALYSIS OF THE GENERA OF ICHTH^LUEI. 



*. Adipose lia with its posterior margin free, not counected with the caudal fin : 

 t. IntermaxiUary band of teeth convex in front, abruptly truncate behind, without 

 lateral backward processes; branchiostegals 8 or 9 (rarely 10 or 11); ventral fins 

 normally with 8 rays : 



t. Supraoccipital bone prolonged backward, its apex einarginato, receiving the 

 pointed anterior end of the second interspinal, thus forming a continuoiis'^bony 

 bridge from the snout to the base of the dorsal ; branchiostegals 8 or 'J ; l)ead 

 elongate; mouth small, terminal, the upper jaw the longer; anal fin elongate, 

 of 24 to 34 rays; caudal fin furcate; body elongate, more or less slender, sii- 

 very, covered with thin skin IcnTn.i:Lri!US 



tt. Supraoccipital bone free behind, not connected with the interspinal : branchi- 

 ostegals normally 9 (varying from 8 to 11); head broad ; mouth broad, tenuiual : 

 anal fin moderate or rather long, with 15 to 27 rays ; caudal fin usually Iruncute, 

 but often more or less deeply emarginate or even forked ; body usually more or 



less shortened, covered with a rather thick skin Amiujjus. 



tt. Intermaxillary baud of teeth convex in front, with a lateral backward extension 

 on each side; branchiostegals normally 12; supraoccipital bone free behind; 

 hea(,l long, broad, and flat ; mouth large, the lower jaw always the longer; anal 

 fin short, of 12 to 14 rays ; ventrals with 9 rays ; caudal fin truncate, its unnierous 

 rudimentary rays recurrent above and below the caudal peduncle; number of 



vertebriB increased; body elongate, covered with thick skin Pelodichthys. 



**. Adipose fin long and low, keel-like, adnato to the back, more or less perfectly con- 

 tinuous with the caudal fin; supraoccipital bone free behind; branchiostegals 

 9 ; anal fin short, with 11 to 20 rays ; caudal fin rounded, with numerous rudi- 

 mentary rays recurrent on the caudal peduncle; ventral rays usually 9; form 

 various, but body usually more or less elongate, depressed in front, compressed 

 behind, covered with a thickish but semi-transparent skin ; size small, Notukl'S. 



CATALOGUE OF NOMINAL SPECIES, WITH IDENTIFICATIONS. 



In the following list are given, in chronological order, the names thus 

 far proposed for our fresh-water Silurldw. In the right-hand eoluinu is 

 my identification of each species. Those species of which I have ex- 

 amined the original types are designated by a star (*), 



