SOUTH AMERICAN NEMATOGNATHI. 69 



little convex. We have examined three specimens .16, 

 ,23, and .28 m. Bahia; Maranhao. Two of them have 

 no teeth on the vomer, the specimen .23 m. long has a 

 single patch on one side of the vomer. 



38, Tachisurus dubius, 



Netuma dubia Bleeker, Versl. en Mededeel. Acad. Wet. Arnsterd. 



1862, xiv, 382 (Surinam); id. Silures de Suriname, 63, plate xv, 



fig. 2, plate xiii, fig. 5, 1864 (Surinam). 



Arius dubius Giinther, Cat. Fish. Brit, Mus. v, 144, 1864 (copied). 

 Galeichthys dubius Jordan, Proc. U. S. Nat. Mus. 1886, 559 (name 



only) . 

 Tachisurus dubius Eigenm. & Eigenm. Proc. Cal. Acad. 2d Ser. vol. 



i, 1888, 141 (name only). 

 Habitat: Surinam. 



39, Tachisurus kessleri, 



Arius kessleri Steindachner, SB. Ak. Wien, Ixxiv, 1876, Ichthyol. 



Beitr. iv, 24, pi. v(Altata; Panama); Jordan & Gilbert, Bull. U. 



S. Fish Comm. 1882, 40 (Panama); Jordan & Gilbert, Proc. U. 



S. Nat. Mus. 1882, 621 (Panama). 

 Galeichthys kessleri Jordan, Proc. U. S. Nat. Mus. 1885, 365 (name 



only). 

 Tachisurus kessleri Eigenm. & Eigenm. Proc. Cal. Acad.*2d Ser. vol. 



i, 1888, 142 (Panama). 

 Habitat: West Coast tropical America. 



Width below the dorsal spine a little greater than the 

 depth, tapering rather rapidly backward to the caudal 

 peduncle. Head depressed, its depth about If in its 

 length, the width 1^-1-^; the width at the mouth about 

 If; profile forming a gentle and nearly even curve; 

 snout about 3J in the head. Top of head coarsely gran- 

 ular, the region between the fontanel and base of occip- 

 ital process being more or less granular striate; a ridge 

 bounds the fontanel, and one extends forward about 

 midway between this and the margin of the eye, the 

 ridges sometimes somewhat striate or granulate, usually 

 nearly smooth. Occipital process longer than broad, 

 keeled, sub-truncate or emarginate, meeting the rather 

 small dorsal plate which is granular in front; opercles 

 slightly striate, but covered with skin which with the 



