SOUTH AMERICAN NEMATOGNATHI. 95 



genera, but the species are too suspiciously alike, and 

 the genera are based on characters easily mistaken; so 

 we do not feel any hesitancy in uniting the species and 

 genera. If there are three genera, we have the anoma- 

 lous fact that three closely related genera inhabit the 

 Amazon, the species of which agree in everything but 

 their generic characters. 



67. Callophysus macropterus. 



Pimelodus macroi^ter us Lichtenstein, Wiede. Zool. Mag i, part iii, 



59, 1819 (Brazil). 

 Callojihysus macropterus Mttller & Troschel in Schomburgk Brit. 



Guiana, 629, 1848 (Essequibo); Idem Horsi Ichthyol. iii, 1, 1849. 



(Brazil; Guiana); Gtinther Cat. Fish. Brit. Mus. 137, 1864 



(copied); Peters, MB. Ak. Berl. 470, 1877, (Apure); Eigenm. & 



Eigenm. Proc. Cal. Acad. 2d Ser. vol. i, 1888, 120 (Obidos; Lake 



Jose Assu; Cameta; Kio Negro; Sautarem; Tonantins; Manaca- 



puru). 

 Pimelodus ctenodus Agassiz, Gen. Spec. Pise. 21, plate viii, a, 1829 



(Equatorial Brazil); Cuv. & Val., Hist. Nat. Poiss. xv, 186, 1840 



(copied); Castelnau, Anim. Nouv. Eares de I'Amer. de Sud. 35, 



1855 (Amazon). 

 Callophysus ctenodus Miiller & Troschel, Horaj Ichthyol. iii, 2, 



1849 (Brazil). ? Kner, SB. Ak. Wieu, xxvi, 1857, 422 (loc.?); 



Giinther, Cat. Fish. Brit. Mus. 1.37 1864 (copied). 

 Pimelodus insignis Schomburgk, Fish. Brit. Guiana, i, plate vi (not 



description). 

 Pimeloiropis lateralis Gill, Proc. Acad. Nat. Sci. Philad. 1859, 196 



(Amazon). 

 Callophysus lateralis Giinther, Cat. Fish. Brit. Mus. 136, 1864 



(copied); Steindachuer, SB. Ak. Wien, Ixxiv, 1876, Ichthyol. 



Beitr. v, 105. (Santarem; Tabatinga; Montalegre; Obidos; Kio 



Negro; Tonantins; Lake Manacapuru; Jose Assu); Cope. Proc. 



Am. Philos. Soc 17, 1878, 676 (Peruvian Amazon); Vaillant, 



Bull. Soc. Philom. series 7, iv, 1880 (Calderon). 

 Habitat: Amazon and its tributaries and northward. 



We have examined 30 specimens measuring from .125 

 m. to .43 m. They are from Obidos; Lake Jose Assu; 

 Cameta; Rio Negro; Santarem; Tonantins; Lake Man- 

 acapuru; Villa Bella; Serpa. 



The inner ray of the ventral fins is sometimes divided 

 to the base, accounting for the number " 7 " of the ven- 

 trals in P. ctenodus Agassiz. 



