2. MONociREnus. 371 



with brown, and with scattered silvery spots ; an oblique brown 

 streak from the eye to the angle of the pra^opcrculum. The spinous 

 portions of the vertical fins and the vcntrals dark brown, the soft 

 portions and the pectorals whitish. A small patch of teeth on each 

 side of the vomer, and a narrow band on the palatine bones. 

 Essequibo. 



a. Fine specimen, three inches and a half long. Presented by Sir 

 E.. Schomburgk. 



MiiUer and Troschel examined a young specimen of this species : 

 hence the discrepancies between our description and theirs. 



2. Polycentrus tricolor. 

 Gill, I. c. p. 373. 



Light brown, longitudinally striped with darker; head and verti- 

 cal fins M-ith black dots. (GilL) 

 Trinidad. 



Gill does not make mention of palatine teeth in this species. 



2. MONOCIRRHUS. 



Monocirrhus, Seckel, Ann. Wien. Mus. ii. 1840, p. 439. 



The body is compressed, elevated, covered with rough scales ; the 

 mouth is very protractile. Villiform teeth in the jaws ; none on the 

 vomer. The lower lip jjrolonged into a fleshy barbel. Praeorbital 

 and prffiopereulum not serrated. Lateral line none. One dorsal, with 

 seventeen spines, the anal with thirteen ; none of the rajs branched ; 

 ventrals thoracic, composed of one sjiine and five rays. Six branchio- 

 stegals ; the gill-membranes not united. Three gills ; pseudo- 

 branchia; hidden. 



Fresh waters of Brazil. 



1 . Monocirrhus polyacanthus. 



Heckd, I. c. 

 D. jZ. A. ||. V. 1/5. L. lat. 35. L. transv. 25^26. 



Head pointed. Light brown, with three black streaks on the side 

 of the head, radiating from the eye ; a dark band from the gill- 

 ojiening along the lower half of the tail. 



Ponds near the Rio Negro. Tributaries of the Amazon. 



a. River Cupai, 800 miles from the sea. From Mr. Bates's Collection. 



2 B 2 



