SOUTH AMERICAN NEMATOGNATHI. 299 



SUBFAMILY AGENEIOSESLE. 

 LIV. AGENEIOSUS. 



Ageneiosus Lacepede, Hist. Nat. Poiss, v, 132, 1805 

 (ar mains). 



Ceratorhynchus Agassiz. 



Hypophthalmus Schomburgk, Fish. Brit. Guiana, 191, 

 1849 (dawalla). 



Pseudageneiosus Bleeker, Nederl. Tijdschr. Dierk. i, 

 1863 (brevifilis). 



Davalla Bleeker, 1. c. (davalla). 



Ageniosus Giinther, Cat. Fish. Brit. Mus. v, 191, 1864 

 (sp). 



Type: Ageneiosus armatus Lacepede. 



Barbels at the maxillaries only. Teeth villiform, none 

 on the palate. Eyes large, lateral. Orbit without a free 

 margin. Adipose fin very short; dorsal fin of a weak 

 spine and 6 or 7 rays. Anal long. Ventrals behind 

 the dorsal, with 7 or 8 rays, the inner one joined to the 

 sides for at least half its length. Bases of pectorals more 

 or less horizontal. Humeral process none. Lateral line 

 zigzag, with numerous branches. Occipital process firmly 

 joined to the dorsal plate. Gill-membranes confluent 

 with the skin of the isthmus. Bones of the head thin, 

 covered with thin skin. 



Habitat: La Plata, and its tributaries; Paranahyba 

 northward to Guiana and westward to Peru. 



DOUBTFUL SPECIES. 



235.1. Silurus inermis Linnaeus, Syst. Nat. ed. xii, 

 503, 1766 (Surinam); Bloch, Ausland. Fische, pt. 8, pi. 

 363, 1794. Ageneiosus inermis Eigenm. & Eigenm. 

 Proc. Cal. Acad. 2d Ser. i, 149, 1888 (name only). 



