238 MEMOIRS OF THE CARNEGIE MUSEUM 
The pectoral thorns are 17, 18, 22, and 23 in different specimens, the largest 
number being found in 7542 M. C. Z. from Manacapurt. It is quite possible 
that most of the specimens from north of the Paraguay basin heretofore referred 
to P. gracilis really belong to this species. The specimens at present in the Museum 
of Comparative Zodlogy are: 
7566a—b. 95-126 mm. to base of caudal, Maues, Rio Madeira. Thayer Expedi- 
tion. 
7a.” 190 mm., Para. Thayer Expedition. 
2a. 172 mm., Cudajas. Thayer Expedition. 
He 
7a. 137 mm., Santarem. Thayer Expedition. 
154 mm., Rio Puty. Thayer Expedition. 
542a. 212 mm., Manacapurti. Thayer Expedition. 
SS 
¢ oS 
(06) 
= 
4. Pimelodella gracilis (Cuvier & Valenciennes). 
Pimelodus gracilis Cuvier & VALENCIENNES, His. Nat. Poiss., XV, 1840, p. 181 
(Buenos Ayres; Parand at Corrientes); VALENCIENNES, Voy. d’Orbigny, Vol. 
V, 1847, Poissons, p. 6, plate II, fig. 5; Kner, Sb. Ak. Wiss. Wien, X XVI, 
1857, p. 418 (Caigara, Mattogrosso; Rio Guaporé; Cujaba); GinTuer, Cat. 
Fishes Brit. Mus., V, 1864, p. 121; BouLencsEr, Trans. Zo6l. Soc., 1896, p. 27 
(Descalvados). Rinmh. AD. Wer Wrin bef 7/, hl5? 1577 
Pimelodus (Pseudorhamdia) gracilis? STEINDACHNER, Flussfische Siidam., I, 1879, 
p. 9 (Orinoco near Ciudad Bolivar). 
Pimelodella gracilis EIGENMANN & EIGENMANN, Proc. Cal. Acad. Sci., (2), I, 
1888, p. 1382 (Goyaz); ? Occasional Papers Cal. Acad. Sci., I, 1890, p. 153; 
Proc. U. 8. Nat. Mus., XIV, 1890, p. 29; Ann. Carnegie Mus., IV, 1907, 
p. 114, pl. XXXII, fig. 2 (Corumbé; Laguna Ypagarai); EtGENMANN, Reports 
Princeton Univ. Exped. Patagonia, III, 1910, p. 389. 
Rhamdia gracilis Rrperro, Fauna Bras., Peixes, [V, 1912, p. 269. 
Pimelodus lateristriga BOULENGER (non Miiller & Troschel), Trans. Zo6l. Soc. Lond., 
1896, p. 27 (Descalvados). 
Pimelodus (Pimelodella) teniophorus Reaan, Ann. and Mag. Nat. Hist. (7), XII, 
1903, p. 625 (Desealvados). 
Habitat.—La Plata Basin; Uruguay. Basin; ? Amazon; ? Orinoco. More 
abundant in the La Plata Basin than elsewhere. 
In 6947 the maxillary barbel in specimens between 78 and 112 mm. long extends 
beyond the base of the caudal; in the specimens 97 mm. long to the end of the 
* Tn this specimen the dorsal spine is very high, equal to the length of the head. Pectoral thorns 22. 
