"238 CALIFORNIA ACADEMY OF SCIENCES. 



3d; all the plates more or less concealed beneath the 

 skin, having a strong median hook, and from none to 2 

 marginal spines below, and from none to 3 marginal 

 spines above the median hook. Several smooth, well- 

 developed plates above and below on the caudal pedun- 

 cle; no plates on the back or belly. 



Humeral process large, broad, pointed or rounded be- 

 hind, reaching to below the second lateral plate, its sur- 

 face with low vermiculating ridges. 



Distance of the dorsal fin from the snout 2|-2J in the 

 length; dorsal spine slightly curved, as long as the head, 

 its sides striate, its anterior margin with upturned serras, 

 its posterior margin smooth, with a median groove. 

 Space between the dorsal and adipose fins little greater 

 than the base of the latter, which is considerably longer 

 than the dorsal fin. 



Caudal fin emarginate. 



Anal fin higher than long, its margin rounded. 



Ventrals, lf-2 in the head. 



Pectoral spine broad, strong and long, reaching the 

 ventrals or a little shorter; upper and lower surfaces of 

 the spine finely striate, both margins strongly serrate. 



Pectoral pore large, simple. 



Sides and back and the fins covered with minute dark 

 dots. 



Head44-4i; depth 4|-5f; D.I, 6; A. 11; V. 6; P.I, 8; 

 Lat. 1. 30-31. 



Two specimens, .27 m. Rio San Francisco; Rio das 

 Velhas. Allen & St. John. 



176. Doras affinis. 



Doras affinis Kner, SB. Ak. Wieu, xvii, 1855, 121, pi. ii, fig. 1 (Rio 

 Branco; Guapore); Giinther, Cat. Fish. Brit. Mus. v, 202, 1864 

 (copied). 



AmUydoras affinis Bleeker, Nederl, Tijdschr. Dierk. i, 17, 1863 

 (name only). 



Doras truncatus Bleeker, 1. c. 18. 



Habitat: Rio Branco and Rio Guapore. 



