236 MEMOIRS OF THE CARNEGIE MUSEUM 
Dorsal spine straight, slender, equal to length of head less opercle, 17 minute 
teeth on the upper 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 (Miiller & Troschel) (Plate XXIX, fig. 2). 
Pimelodus cristatus Mtuuer & TroscHEeL, in Schomb. Reisen in Brit. Guiana, 
III, 1848, p. 628 (Takutu and Mahu Rivers); Hore Ichth., III, 1849, p. 4 
(Essequibo); GGnTHER, Cat. Fishes Brit. Mus., V, 1864, 117 (Guiana; Esse- 
quibo; River Capin; Para); VarLuant, Bull. Soe. Philom. (7), 1880, p. 152 
(Calderon); STEINDACHNER, Flussfische Siidam., IV, 1882, p. 4 (Rio Hual- 
laga); ? Peruaia, Ann. Mus. Genova (2), X, 1891, p. 631 (Tucuman). 
Pimelodella cristata EIGENMANN & EIGENMANN, Proc. Cal. Acad. Sci. (2), I, 1888, 
p. 182 (San Goncallo; Avary; Villa Bella; Jutahy; Tapajos; Rio Mucuri;! 
Tabatinga; Hyavary; Coary); Occasional Papers Cal. Acad. Sci., I, 1890, 
p. 150; Proc. U. 8. Nat. Mus., XIV, 1891, p. 29; Eigenmann & Bean, Proc. 
U.S. Nat. Mus., XX XI, 1907, p. 660 (Amazon) ; ErgeNMANN, 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); Fowimr, Proce. Acad. Nat. Sci. 
Phila., 1915, p. 214 (type of ophthalmicus). 
Pimelodus agassizii STEINDACHNER, Sb. Akad. Wiss. Wien, LX XIV, 1876, Flussf. 
Siidéstl. Bras., III, p. 56, footnote (Essequibo). 
Pimelodus (Pseudorhamdia) wesselii STEINDACHNER, Sb. Akad. Wiss. Wien, LX XIV, 
1876, Siisswasserf. Siidéstl. Bras., II, p. 56 (Essequibo). 
Rhamdia wesselii Rrperro, Faun. Bras., Peixes, IV, 1912, p. 268. 
Pimelodus ophthalmicus Corr, Proc. Am. Phil. Soc., XVII, 1876, p. 675 (Upper 
Amazon). 
Habitat.—Guiana, Amazon Basin to the Huallaga, and the Guaporé. 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. Zodl.) 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. 
