224 silitrid^:. 



long, its length being two-ninths of the total (without caudal) ; the 

 eyes are very small, directed upwards, situated in the middle of the 

 length of the head. The mouth is situated at the lower side of the 

 snout ; a barbel, half as long as the head, at each angle of the mouth. 

 Teeth in a narrow band in each ja-w ; those of the outer series in the 

 upper jaw are narrow and not notched, whilst the hinder ones have 

 a distinct notch ; mandibulary teeth broader than the upper ones, 

 notched. The labial fold is emarginate behind. The outer ray of 

 each fin is thickened, flexible, slightly prolonged, and provided with 

 small spines directed backwards ; the outer pectoral and ventral rays 

 subequal in length, the former extending nearly to the second third 

 of the length of the ventral fin ; the origin of the dorsal is somewhat 

 posterior to that of the ventral. Ray of the second dorsal fin one- 

 fourth as long as the head. 



a-d. Two inches long. From the Collection of Madame I. Pfeiffer. 



2. Stygogenes cyclopum. 



Pimelodus cyclopum, Humb. Observ. Zool. i. p. 21. pi. 6. 

 Arges cyclopum, Cuv. fy Val. xv. p. 340. 



B. 4. D. 6. A. 7. C. 12. P. 9. V. 5. 



Adipose fin small, without ray. 

 Subterranean waters in the Andes of Quito. 



90. BRONTES. 



Brontes, Cuv. fy Vol. xv. p. 341. 



Adipose fin none ; /lorsal and anal short, without pungent spine. 

 Teeth small, slightly curved, notched at the apex, forming a narrow 

 band in each jaw ; palate toothless ; cleft of the mouth rather narrow, 

 with a maxillary barbel on each side ; a short broad flap before the 

 posterior nostril, which is close to the anterior ; lower lip very broad, 

 pendent. Eyes minute. Head covered with soft skin. Gill-open- 

 ings separated by a broad isthmus. Ventrals six-rayed, inserted 

 below the end of the dorsal. 



Andes. 



1. Brontes prenadilla. 

 Cuv. 8r Val. xv. p. 343. pi. 445. 



B. 4. D. 7. A. 7. P. 7. V. 6. 

 Upper lip thick, prominent ; barbels slender, shorter than the head ; 

 caudal rounded. Coloration uniform. ( Val.) 



This small species is found in rivulets descending the Cotopaxi, 

 and is one of those which are said to be ejected by volcanic action. 



91. ASTROBLEPUS. 



Astroblepus, Humboldt, Observ. Zool. i. p. 19. 

 Adipose fin none ; dorsal and anal short, without pungent spine ; 

 ventral fins absent. Dorsal situated in the anterior half of the height 



