436 PROCEEDINGS OF THE ACADEMY OF [Oct., 



alcohol dull brownish, back darker than lower surtace and every- 

 where more or less sheened with dull silvery. A dusky blotch at base 

 of caudal and another rounded one on humeral region. Former 

 extends midway on side of caudal peduncle, and medianly out on 

 caudal. Humeral spot in a pale area bordered posteriorly with dusky. 

 Also a dusky streak sloping down from humeral spot towards pectoral. 

 On scales just behind gill-opening above base of pectoral a dusky shade. 

 Fins all pale brownish. Iris brownish with a chestnut ring. Length, 

 caudal damaged, 4f inches. Type. 



The other cotypes show: Head 3i to 34; depth 2 to 2f ; D. in, 8 

 rarely, usually, in, 9, and occasionally iii, 10; A. iv, 21, i to iv, 27, i, 

 usually 25, i, or 26, i; scales 31 to 34 in lateral line to base of caudal, 

 and mostly 2 or 3 more on latter; 6 to 8 scales obhquely back from 

 origin of dorsal to lateral line, usually 7; 5 to 7 scales obliquely or 

 vertically between origin of ventral and lateral line, usually 6, less 

 frequently 7, and rarely 5; 12 to 16 scales before dorsal, mostly 14, 

 sometimes 13, less frequently 15 and rarely 12 or 16; pectoral U to 

 1^ in head ; ventral li to If ; total length of specimens l^f to U inches. 

 Cope's figure fails to indicate the anterior anal rays as a little longer 

 than the others. The young appear more evenly ellipsoid than the 

 adults. 

 Astyanax atahualpianus sp. nov. Fig. 36. 



Tetragonopterus agassizii Cope, Proc. Amer. Philos. Soc. Phila., XVII, 

 1877-78 (May 17, 1878), p. 691. Near Pebas. Prof. J. Orton. 



Head 3f ; depth 2|; D. iii, 9; A. iii, 21 ; P. i, 11 ; V. i, 7; scales (squa- 

 mation damaged) about 24? in lateral line to base of caudal, and 2 or 3 

 more evidently on latter; about 6? scales obliquely back from origin 

 of dorsal to lateral line; about 4? scales vertically from origin of anal to 

 lateral line; width of head about 2^ in its length; depth of head, over 

 middle of orbit, 1^; mandible 2|; least depth of caudal peduncle 2f ; 

 snout 3f in head, measured from tip of upper jaw; eye 2f ; maxillary 

 2 ; interorbital space 2f . 



Body elongate, rather ellipsoid, well compressed, upper profile 

 perhaps a little more convex, and greatest depth apparently at origin 

 of dorsal. Caudal peduncle compressed, and its least depth about 

 equal to length. 



Head moderately short, deep, compressed, muzzle blunt and heavy, 

 and upper profile nearly straight from snout to occiput. Snout short, 

 rather narrow, and surface convex. Eye circular, a little anterior and 

 superior. Mouth large and a little inclined. Maxillary long, oblique, 

 its greatest width a trifle more than half of pupil, and its posterior 



