188 CALIFORNIA ACADEMY OF SCIENCES. 



Maxillary barbels reaching to the tip of the pectorals; 

 adipose fin four times as long as the anal, 3 in the total 

 length, caudal fin slightly emarginate; D. I, 7; A. 9. 



This species is known only from Castelnau's descrip- 

 tion and figure. 



XXVII. Phractocephalus. 



Phradocephalus Agassiz, Gen. et Spec. Pise, Bras. 22, 

 1829 (bicolor = heTniliopteriis) . 



Type: Silurus hemilio2Jterii.s Bloch & Schneider. 



Body rather short, head very broad in proportion; 

 Upper portion of head with vermiculating elevations. 

 Occipital process broad, rounded behind, not quite reach- 

 ing to the broad reniform dorsal plate. Upper half of 

 adipose fin usually rayed. 



138. Phractocephalus hemiliopterus. 



Silurus hemiliopterus Bloch & Schneider, "Syst. Ichthyol. 385, 

 1801." 



Phractocephalus hemiliopterus Cuv. & Val. Hist Nat. Poiss. xv, 3, 

 plate 421, 1840; Schomburgk, Fishes of Giiiana, part i, 169, 

 1841 (Guiana everywhere); Miiller & Troschel, Schomburgk, 

 Brit. Guiana, 643, 1849 (all rivers of Guiana); Castlenau, Auim. 

 Amerique du Sud, 47, plate xv, fig. 4, 1855 (Rios Crixas, Araguay, 

 Amazon); Giinther, Cat. Fish. Brit. Mus. v, 110, 1864 (River 

 Cupai); Vaillant, Bull. Soc.Philom. series 7, iv, 152, 1880 (Cal- 

 deron); Cope, Proc. Am. Philos. Soc. 17, 1878 674, (Peruvian 

 Amazons); Eigeum. & Eigenm. Proc. Cal. Acad. 2d Ser. i, 135, 

 1888 (Xingu; Coary; Teflft'; Manacapuru; Obidos; Lake Hyau- 

 uary). 



Phractocephalus bicolor Agassiz, Gen. Spec. Pise. Bras. 23, 1829 

 (Amazon). 



Pirarara bicolor Spix, Gen. Spec. Pise. Bras. 23, plate vi, 1829 

 (Amazon). 



Habitat: Amazon, Solimoens, Marauou, their tributaries and north- 

 ward. 



This species attains a size of over 1.20 m. 



The s.pecimens examined vary in length from .07-1.00 

 m.; Xingu; Coary; Teflfe; Manacapuru; Obidos; Lake 

 Hyanuary; Villa Bella; Rio Negro. 



