108. HEPTAPTERUS. 271 



Seventh Subfamily. 

 SILURID^ OPISTHOPTER^l. 



The rayed dorsal fin is always present, short, and placed above 

 or behind the middle of the length of the body, above or behind 

 the ventrals, which, however, in one genus are absent ; anal short. 

 Nostrils remote from each other ; if a nasal barbel is present, it 

 belongs to the anterior nostril. Lower lip not reverted. The gill- 

 membranes are not confluent with the skin of the isthmus. 



South America. 



Fifteenth Group. NEMATOGENYINA. 

 Dorsal fin above the ventrals. 



108. HEPTAPTERUS. 



Heptapterus, Bleek. Prodr. Silur. p. 197. 



Adipose fin long, low, confluent or nearly continuous with the 

 caudal ; a short dorsal fin with seven rays, the first being scarcely 

 spinous ; anal fin of moderate length. Barbels six. Palate eden- 

 tulous. Head and body covered with soft skin, much elongate ; eyes 

 small. Caudal fin obliquely rounded; ventral fin with six rays, 

 inserted below the dorsal. 



South America. 



1. Heptapterus surinamensis. 



Bleeker, Versl. in Mededeel. Akad. Wet. Amsterd. 1862, xiv. p. 387. 

 B. 8-9. D. 7. A. 18. P 9. 

 The height of the body is rather less than one -half of the length 

 of the head, which is one-sixth of the total (without caudal) ; jaws 

 equal in length. The maxillary barbel extends nearly to the base 

 of the pectoral. The adipose fin is not confluent with the caudal, 

 and its distance from the dorsal equals its length ; the first ventral 

 ray is situated before the vertical from the origin of the dorsal fin. 

 (Bl.) 

 Surinam. 



2. Heptapterus mustelinus. 



Pimelodus mustelinus, Valenc. in d 1 Orb. Voy.Amer. Merid. Poj'ss.pl. 2. 

 fig. 1 ; Cuv. <$• Val. xv. p. 165. 



B. 9. D. 7. A. 18. P. 8. Vert. 13/41. 

 The height of the body is one-half of the length of the head, which 

 is one-seventh of the total (with the caudal) ; jaws equal in length. 

 The maxillary barbel extends to the gill- opening. Caudal fin 



