eigenmann: the FRESHWATER FISHES OF BRITISH GUIANA 139 



Selenaspis Bleeker. 

 Selenaspis Bleeker, Ichth. Arch. Ind. Prodr., I, 1858, 62 (herzbergii). 

 Leptarius Gill, Proc. Acad. Nat. Sci. Phila., 1863, 170 (dowii). 



Type, Silurus herzbergii Bloch. 



This genus is distinguished from Sciadeichthys by the internarial membrane. 

 The character is scarcely of generic importance, especially since in the young of 

 S. prodps a slit or incipient membrane is often present between the posterior nares. 



Two species are found on the Atlantic coast of America, and a third one on 

 the Pacific coast of Panama. 



Key to the Species of Selenaspis. 

 a. Upper jaw distinctly longer than lower; snout 3.5 in the head; palatine teeth forming a U-shaped 



figure herzbergii. 



aa. Upper jaw distinctly shorter than the lower; snout about 7 in the head; palatine teeth forming a 

 transverse patch without backward projecting angles passany. 



18. Selenaspis herzbergi (Bloch). (Plate VII, fig. 1.) 

 Silurus herzbergii Bloch, Ausl. Fische, VIII, 1794, 33, pi. 367 (Surinam). — Bloch 



and Schneider, Syst. Ichth., 1801, 383 (Surinam). 

 Bagrus herzbergii Cuvier and Valenciennes, Hist. Nat. Poiss., XIV, 1839, 453 



(Mana; Cayenne) .— Kner, SB. Akad. Wiss. Wien, XXVI, 1857, 386 (Para). 

 Selenaspis herzbergii Bleeker, Ichth. Arch. Ind. Prodr., I, 1858, 63. — Jordan and 



Evermann, Bull. U. S. Nat, Mus. No. 47, 1, 1896, 125.— Eigenmann and Bean, 



Proc. U. S. Nat. Mus., XXXI, 1907, 659 (Amazon). 

 Arius herzbergii Gunther, Catalogue, V, 1864, 144 (British Guiana; Demerara).— 



Vaillant, Nouv. Arch. Mus. d'Hist. Nat., (4), II, 1900, 124 (Mahury, French 



Guiana) . 

 Netuma herzbergii Bleeker, " Silures de Suriname", 1864, 61, pi. 9, pi. 13, fig. 3, 



(Surinam). 

 Galeichthys herzbergii Jordan, Proc. U. S. Nat. Mus., IX, 1886, 559 (name only). 

 Tachisurus herzbergii Eigenmann and Eigenmann, Proc. Cal. Acad. Sci., (2), I, 



1888, 141 (Para; Curuca; Bahia); Occasional Papers Cal. Acad. Sci., I, 



1890, 59. 

 Pimelodus argenteus Lacepede, Hist. Nat, Poiss., V, 1801, 94, 102. 

 Bagrus pemecus Cuvier and Valenciennes, Hist. Nat. Poiss., XIV, 1839, 456 



(Cayenne) . 

 Bagrus mesops Cuvier and Valenciennes, Hist. Nat. Poiss., XIV, 1839, 456.— 



Muller and Troschel, in Schomburgk, Reisen, III, 1848, 627 (Waini and 



