424 CALIFORNIA ACADEMY OF SCIENCES. 



Distance of the dorsal fin from end of snout 2J in the 

 length. Last dorsal ray joined by a membrane to the 

 spine of the adipose fin and to the back. 



Caudal fin obliquely truncate, the lower lobe longest. 



Anal fin inserted under the membrane which connects 

 the two dorsal fins. 



Ventral fins large, reaching entirely beyond the base 

 of the anal. 



Pectorals reaching second 4th of the ventral fins. 



White dots on the head, body, and the rays of all the 

 fins; ventral surface dusky from brown punctulations. 



Head 3; depth 5; D. I, 7; A. 5; Lat. 1. 22. 



One specimen .15 in. % Porto do Moz. Senhor Vinhas. 



392. Parancistrus aurantiacus. 



Hypostomus aurantiacus Castelnau, Anim. Ameriqne du Sud. 43, 



plate xxi, fig. 2, 1855 (Ucayale). 



Chcetostomus aurantiacus Glinther, v, 246, 1864 (copied). 

 Parancistrus aurantiacus Eigenm. & Eigenm. Proc. Cal. Acad. 2d 



Ser. ii, 44, 1889. 

 Habitat: Ucayale. 



This species is imperfectly known from Castlenau's 

 figure and description. 



393. Parancistrus nigricans. 



Hypostomus nigricans Castelnau, 1. c. 44, pi. xxii, fig. 1, (Amazon). 

 Chwtostomus nigricans Giinther, v, 246, 1864 (copied). 

 Parancistrus nigricans Eigenm. & Eigenm. 1. c. 

 Habitat: Amazon. 



This species is known only from the description and 

 plate quoted. 



LXXXVI. COCHLIODON. 



Cochliodon (Heckel, MS.) Kner, Hypostomiden, 265 

 (hypostomus= cochliodon). 



This genus is as yet known from a single species. It 

 is distinguished from Panque by its simple unarmed pre- 

 opercle and from the remaining genera of Plecostominw 

 by its dentition. 



