218 PROCEEDINGS OF THE ACADEMY OF [Apr., 



base. Fins all pale brownish. Iris brownish. Maxillary barbels 

 brownish, and others whitish. 



Length 160 mm. 



Type, No. 8,362, A. N. S. P. Ambyiacu River, near Pebas, 

 Ecuador. John Hauxwell. 



Paratype, No. 8,363, A. N. S. P., same data. Head 4f ; depth 

 5f ; D. I, 5; A. iv, 8, i; snout 2f in head; eye 4; maxillary 4^; 

 interorbital 3|; dorsal spine 1|; pectoral spine Ij; length 152 mm. 



This species was originally identified with Pimelodus lateristrigus 

 Miiller and Troschel by Cope, though at the time he pointed out 

 that it differed somewhat "in the longer beards and one soft ray 

 less in dorsal and anal fin." Eigenmann and Eigenmann state^ 

 that the maxillary barbels reach the ventral tips and the origin of the 

 adipose dorsal, the gill-rakers 3+8, depth 6| to 7, and pectoral spine 

 with unusually strong and sharp retrose hooks along the inner edge. 



(Named for Prof. Edward D. Cope, who first pointed out its 

 characters.) 



Pimelodella cyanostigma (Cope). 



Rhamdia cyanostigma Cope, Proc. Amer. Philos. Soc, XI, 1870, p. 569. 

 Pebas, Ecuador. 



Nos. 8,381 to 83, A. N. S. P., cotypes of R. cyanostigma Cope. 

 Pebas, Ecuador. J. Hauxwell. Eigenmann and Eigenmann state,^ 

 ''we are unable to tell to which genus this species belongs. Dr. Cope 

 says that this species is allied to Pimelodus ophthalmicus = Pimelo- 

 della cristatus. But cristatus' is generically different from Rhamdia, 

 and was generally considered so when the statement was made." 

 However, it is evident that Cope was correct in placing cyanostigma 

 in Pimelodus, as Pimelodella ( = Pseudorhamdia Steindachner) was 

 not proposed until 1888. 



Phractocephalus hemilopterus (Schneider). 



Peruvian Amazon. 

 Brachyplatystoma vaillanti (Valenciennes). 



Surinam. 

 Hemisorubim platyrhynchos (Valenciennes). 



Peruvian Amazon. 

 Pseudoplatystoma fasciatum (Linnteus). 



Nauta, Ecuador, and Surinam. The larger Nauta example has 

 maxillary barbel slightly shorter than depressed dorsal tip, though 

 in the Surinam example it is about even. A. v, 8, i and v, 9, i. 



^ Occas. Papers Cal. Acad. Sci., I, 1890, p. 156. 

 8L.C., p. 164. 



