THE AMERICAN TETRAGONOPTERINAE. 281 



Scales cycloid, with several diverging striae, regularly imbricate, without 

 interpolated scales. 



Anal sheath inconspicuous, of a single series of scales on the anterior two 

 thirds of the fin; a well-developed axillary scale. Lateral line but httle decurved. 

 Caudal sheath on the lobes half as long as the middle rays. 



Origin of dorsal equidistant from snout and base of middle caudal rays, 

 its penultimate ray about half as high as the highest, which is 3^ in the length. 

 Anal emai-ginate, its origin under the middle of the dorsal. Ventrals reaching 

 anal, their origin an orbital diameter nearer the upper lip than the dorsal. Pec- 

 torals reaching one or two scales beyond the origin of the ventrals. 



A silvery lateral band, an obscure humeral spot; tips of middle caudal 

 rays dark, the rest of the middle rays hyaline with traces of color, the caudal 

 lobes opaque. 



36. AsTYANAX GiTON Eigeumaun. 

 Plate 47, fig. 1. 



Astyanax gilon Eigenmann, Bull. M. C. Z., 1908, 52, p. 97; Rept. Princeton univ. exped. Patagonia, 

 1910, 3, p. 432. 



Habitat. — Rio Parahyba, eastern Brazil. 



Two specimens. 20936 Cotypes. About 68- about 78 mm. Rio Para- 

 hyba, Thayer Expedition. 



These two specimens resemble Astyanax taeniatus with a blunt snout. 

 The larger may be considered the type. They differ from A. brevirhinus in the 

 color of the caudal and the shape of the occipital process. 



Head 4; depth 2.5-2.6; D. 11; A. 23-24; scales 5-35-4; eye 2.5; inter- 

 orbital 2.75-3. 



Occipital process not nearly so narrow as in A. brevirhinus; snout a little 

 more than half as long as the eye; two or three teeth in the front row of the 

 premaxillary ; two teeth on the maxillary. 



Gill-rakers 8 + 12. 



Caudal sheath on the lobes more than half the length of the middle rays. 



Dorsal nearly 4 in the length. Origin of anal under posterior part of 

 dorsal or behind the dorsal. 



A prominent humeral spot crossing the third scale of the lateral Une; a 

 large spot at base of caudal continued to the tips of the middle rays. Other- 

 wise as in A. brevirhinus. 



