422 CALIFORNIA ACADEMY OF SCIENCES. 



In a specimen .07 m. long the ventral surface is nearly 

 naked; in one .11 m. long it is entirely covered with 

 granular scutes, which are largest on sides and near the 

 vent. 



All the lateral and dorsal scutes minutely granular, 

 not keeled, the posthumeral keel obtuse. 



Distance of the dorsal fin from the snont 2|-2i in the 

 length. Base of the dorsal fin little less than its dis- 

 tance from the caudal fin. 



Caudal emarginate. 



Adult: Ventral surface plain; the head with retic- 

 ulating light and dark lines; sides of body irregularly 

 marbled with light and dark; dorsal fin with four dark 

 cross-bands; caudal and ventral fins with three cross- 

 bands; pectoral fins with four dark cross-bands. 



Young: A dark band along the posterior margin of 

 the head, a similar band between and below the eyes; a 

 dark band between the nares, and three parallel lines 

 extending forward to the edge of the snout; a dark brown 

 spot or bar above the middle of the pectoral; another bar 

 above the ventral; a dark band below the adipose, and 

 another at the end of the caudal peduncle; dorsal, cau- 

 dal and pectoral fins each with two black bands; anal 

 and ventrals with a single band. 



Head 2f-3; D. I, 7; A. 5; Lat. 1. 23-25. 



Five specimens, .07-. 18 m. Rio Trombetas; Porto do 

 Moz; Tajapuru; Obidos; Avary. 



LXXXV. Parancistrus. 



<CHi/postomus Castelnau, Anim. Amer. Sud. (sp.) 



=zParancistrus Bleeker, Nederl. Tijdschr. Dierkunde, 

 i, 1863, 79 (aurantiacus). 



Type: Hypostomus aurantiacus Castelnau. 



This genus is very closely related to Hemiancistrus 

 from which it differs in its adnate dorsal fin. 



Habitat: Amazon and tributaries. 



