168 MEMOIRS OF THE CARNEGIE MUSEUM 



Type, Pimelodus cristatus Miiller and Troschel. 



Similar to Pimelodus, but with a parietal fontanel persistent throughout life; 

 the occipital process not tapering, but of nearly uniform width, in contact with 

 the dorsal plate behind; no vomerine teeth. 



Species usually slender and of small size. 



Key to the Guiana Species of Pimelodella. 

 a. Adipose fin 2.33-2.5 in the length. A narrow lateral band, conspicuous in young, becoming obscure 



with age. Maxillary barbels to below middle of adipose or beyond tip of caudal cristata. 



aa. Adipose fin 3 or more in the length. 



6. Eye 2.5 in the head, longer than snout; interorbital 2 in the eye; maxillary barbel reaching end of 

 adipose or caudal; caudal lobes long, slender, the lower 3 in the length; pectoral spine little 



shorter than head megalops. 



66. Eye 3.5 in head, shorter than snout; tip of dorsal dusky; maxillary barbel reaching middle of 

 adipose; pectoral spine about equal to snout and eye macturki. 



44. Pimelodella cristata (Miiller and Troschel). 



? Pimelodus insignis Schomburgk, Fishes Brit. Guiana, 1, 1841, 180 (not plate). — 

 Muller and Troschel, in Schomburgk, Reisen, III, 1848, 643 (Takutu and 

 Rio Branco). 



Pimelodus cristatus Muller and Troschel, in Schomburgk, Reisen, III, 1848, 628 

 (Takutu and Mahu Rivers); Horae Ichth., Ill, 1849, 4 (Guiana, in Esse- 

 quibo). — Gunther, Catalogue, V, 1864, 117 (Guiana; Essequibo; River Capin, 

 Para).— Vaillant, Bull. Soc. Philom., (7), IV, 1880, 152 (Calderon) .— Stein- 

 dachner, " Flussfische Siidamerika's," iv, 1882, 4 (Rio Huallaga). — ? Perugia, 

 Ann. Mus. Genova, (2), X, 1891, 631 (Tucuman). 



Pimelodella cristata Eigenmann and Eigenmann, Proc. Cal. Acad. Sci., (2), 1, 1888, 

 132 (San Goncallo; Avary; Villa Bella; Jutahy; Tapajos; Rio Mucuri; 

 Tabatinga; Hyavary; Coary); Occasional Papers Cal. Acad. Sci., I, 1890, 150.— 

 Eigenmann and Bean, Proc. U. S. Nat. Mus., XXXI, 1907, 660 (Amazon).— 

 Eigenmann, Repts. Princeton Univ. Exp. Patagonia, III, 1910, 388. 



Pimelodus agassizii Steindachner, " Icthyologische Beitrage," v, 1876, 99 

 (Peruvian Amazon; Hyavary). 



Pimelodus (Pseudorhamdia) wesselii Steindachner, " Stisswasserfische Siidostlichen 

 Brasilien," iii, 1876, 56, footnote (Essequibo). 



? Pimelodella wesselii Eigenmann and Eigenmann, Proc. Cal. Acad. Sci., (2), I, 

 1888, 132 (Cudajas; Para; Marajo; Rio Madeira; Rio Puty; Santarem); 

 Occasional Papers Cal. Acad. Sci., I, 1890, 152. 



Pimelodus ophthalmicus Cope, Proc. Am. Philos. Soc, XVII, 1878, 675 (Upper Ama- 

 zon). 



