412 ORDER MALACOPTERYGII ABDOMINALES. 



their head, and the enlargement of the anterior part 

 of the trunk, which particularly results from the 

 breadth of the humeral bones ; in the proportional 

 length of the tail ; in the small eyes placed at the 

 superior face ; in their intermaxillaries inclined under 

 the ethmoid, directed backwards, and supporting 

 teeth only at their posterior edge ; finally, in the 

 circumstance that they are the only osseous fishes 

 known, which have no mobility in the operculum, 

 because the pieces which should compose it are 

 cemented to the tympanic bone, and to the preoper- 

 culum. The aperture of the gills is formed by a 

 simple cleft of the skin, under the external edge of the 

 head, and their membrane, which has five rays, is 

 adherent every where else. The under jaw is trans- 

 verse, and the muzzle advances beyond it. The first 

 pectoral ray is armed with thicker teeth than in any 

 other silurus ; there is but a single dorsal on the front 

 of the back, whose first ray is not very stout; the 



the genus Macroramphose, Lacep. ; it is nothing but the Centriscus 

 Scolopax, L. 2. The genus Pogonatus, Commers. and Lacep. 

 The first species Pogonatus courbin, Lacep. v. p. 122, is no other 

 than the Pogonias, Lacep. II. xvi. 2, and III. p. 138, and conse- 

 quently of the family of the Scisenae ; the other, Pogonatus auratus, is 

 evidently of the genus Umbrina. 3. The genus Centronodon, 

 Lacep., or Silurus imberbis, Houttuyn. Act. Haarl. xx. 2. 338 ; it is 

 in no sense a silurus, since it has scales, prickles to the operculum, 

 the first dorsal spiny, &c. It probably approximates to the perches, 

 and Bloeh, very gratuitously Edit, of Schn. p. 110, ranges it among 

 the Sphyrsenae. 



