THE AMERICAN TETRAGONOPTERINAE. 263 



Occipital process very narrow, its width not quite half its length which is 

 about I as long as the distance from its base to the dorsal, bordered by three 

 scales on the sides. Interorbital smooth and convex. Frontal fontanel a 

 Uttle narrower and a Uttle shorter than the parietal. Second suborbital leaving 

 a considerable naked area which is widest below. Mouth large. Maxillary 

 a little longer than the eye. Normally four teeth in the outer series of the 

 premaxillary of which the third is withdrawn from the line of the rest; five 

 teeth in the second series. Maxillary with three small teeth. Mandible with 

 four large teeth in the dentary and abruptly minute ones on the side. 



Gill-rakers 6 + 14, those of the upper arch excessively minute, those of 

 the lower arch about ^ the length of the eye. 



Scales of the sides regularly imbricate, no interpolated scales over the 

 anal; scales of the ventral surface less regularly imbricate. 



Anal sheath composed of a single series of scales along the base of the 

 anterior rays. Lateral hne but Uttle decm-ved. 



Ventrals but little in advance of the vertical from the dorsal, which is a 

 little nearer the snout than the caudal; highest dorsal ray about 4 in the length. 

 Anal emarginate, the second and fom-teenth rays reaching the base of the twen- 

 tieth ray. Ventrals not reaching anal. Pectorals just to ventrals. 



Coloration much as in ^. abramoides, a dark bar crossing opercle, a second 

 bar some distance behind this in a light area, the second bar widest above the 

 lateral line where it forms an indistinct humeral spot; a third bar shading into 

 the thickly dotted sides; cheeks thickly punctate, a dark dorsal streak. A 

 black band crossing the base of the caudal and sometimes extending out along 

 the outer rays. No dark line along the sides in formalin specimens, sometimes 

 dark streaks up and down from the median Une between segments of muscle. 



25. AsTYANAX (Zygogaster) stilbe (Cope). 

 Plate 43, fig. 3. 



Tdragonopterus stilbe Cope, Proc. Amer. philos. soc, 1870, H, p. .559 (Para) ; Eigenmann & Eigenmann, 

 Proc. U. S. N. M., 1891, 14, p. 54; Ulrey, Ann. N. Y. acad. sci., 189.5, 8, p. 275. 



Astyarmx stilbe Fowleb, Proc. Acad. nat. sci. Phil., 1906, p. 4.31, fig. 34 (Para); Eigenm.\nn & Ogle, 

 Proc. U. S. N. M., 1907, 33, p. 28 (Para); Eigenm.\nn, Kept. Princuton univ. expcd. Patagonia 

 1910, 3, p. 433. 



Habitat: Para and Atrato Basin. 



