236 MEMOIRS OF THE CARNEGIE MUSEUM 



Dorsal spine straight, slender, equal to length of head less opercle, 17 minute 

 teeth on the ui^per two-thirds of the posterior surface, the anterior margin smooth ; 

 pectoral spine heavy, little longer than dorsal spine; 18-21 strong retrorse teeth 

 along nearly the entire posterior margin, longest near the middle of the spine; 

 25-50 shorter, mostly antrorse teeth along all but a short space near the tip along 

 the anterior face. Caudal lobes nearly equal, about 3.5 in the length. 



Occipital process of nearly the same width throughout, firmly united with 

 the dorsal plate. No color-markings. 



2. Pimelodella cristata (Miillcr & Troschel) (Plate XXIX, fig. 2). 



Pimelodus cristatus Muller & Troschel, in Schomb. Reisen in Brit. Guiana, 

 III, 1848, p. 628 (Takutu and Mahu Rivers); Horse Ichth., Ill, 1849, p. 4 

 (Essequibo); Gunther, Cat. Fishes Brit. Mus., V, 1864, 117 (Guiana; Esse- 

 quibo; River Capin; Para); Vaillant, Bull. Soc. Philom. (7), 1880, p. 152 

 (Calderon); Steindachner, Flussfische Siidam., IV, 1882, p. 4 (Rio Hual- 

 laga); ? Perugia, Ann. Mus. Geneva (2), X, 1891, p. 631 (Tucuman). 



Pimelodella cristata Eigenmann & Eigenmann, Proc. Cal. Acad. Sci. (2), I, 1888, 

 p. 132 (San Gon^allo; Avary; Villa Bella; Jutahy; Tapajos; Rio Mucuri;'' 

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

 p. 150; Proc. U. S. Nat. Mus., XIV, 1891, p. 29; Eigenmann & Bean, Proc. 

 U. S. Nat. Mus., XXXI, 1907, p. 660 (Amazon); Eigenmann, Reports Prince- 

 ton Univ. Exped. Patagonia, III, 1910, p. 388; Mem. Carnegie Mus., V, 

 1912, p. 168 (Tumatumari; creek below Potaro Landing; Rockstone; Kona- 

 waruk; below Packeoo Falls; Twoca Pan); Fowler, Proc. Acad. Nat. Sci. 

 Phila., 1915, p. 214 (type of ophthalmicus). 



Pimelodus agassizii Steindachner, Sb. Akad. Wiss. Wien, LXXIV, 1876, Flussf. 

 Siidostl. Bras., Ill, p. 56, footnote (Essequibo). 



Pimelodus {Pseudorhamdia) wesselii Steindachner, Sb. Akad. Wiss. Wien, LXXIV, 

 1876, Siisswasserf. Siidostl. Bras., II, p. 56 (Essequibo). 



Rhamdia wesselii Ribeiro, Faun. Bras., Peixes, IV, 1912, p. 268. 



Pimelodus ophthalmicus Cope, Proc. Am. Phil. Soc, XVII, 1876, p. 675 (Upper 

 Amazon) . 

 Habitat. — Guiana, Amazon Basin to the Huallaga, and the Guapore. Rio 



Mucuri. 



My reference in former papers of Schomburgk's insignis to this species is 



wrong. 



* In three of the four specimens from Santa Cruz, Rio Mucuri (No. 7412 Mus. Comp. Zool.) the 

 caudal is considerably longer than in specimens from the Amazon, 4-4.5 in the length. The upper 

 caudal lobe is usually narrower and more pointed than the lower. 



