1913.] NATURAL SCIENCES OF PHILADELPHIA. 537 



SO that it is but little shorter than entire anal basis, anterior branched 

 rays soon sloping down and greater part of fin low. Caudal longer 

 than head, well forked, lobes pointed and equal. Pectoral large, 

 low, broad, upper rays longest, and fin extends a little beyond ventral 

 base. Ventral inserted nearer anal than pectoral, also extends back 

 a little beyond front of former. Yent close behind ventral roots, 

 remote from anal. 



Color in alcohol pale l)rownish, lower surface scarcely paler. 

 Back and surface of trunk above anal base finely punctate with 

 minute dusky dots. Humeral region, rather narrow lateral streak 

 medianly, abdomen and lower surface of head, silvery- white. 



Head brownish above. Iris whitish, pupil slaty. A very pale 

 humeral blotch vertically ovoid and its length in vertical diameter 

 about equals that of eye. No caudal blotch. Fins all pale. 



Length .53 mm. 



Type, No. 39,218, A. N. S. P. Tributary of the Madeira River near 

 Porto Velho, Brazil. January-February, 1913. Edgar A. Smith. 



Also No. 39,219, A. N. S. P., paratype, same data. Head 4; 

 depth 3; D. ii, 8; A. iii, 32, i; scales 38 in lateral series to caudal 

 base, and 3 more on latter; 11 tubes in 1. 1.; 12 scales in transverse 

 series between dorsal and anal origins; 15 scales before dorsal to 

 occipital process; snout 4 in head, measured from upper jaw tip; 

 eye 3; maxillary 2|; interorbital 3; length 46 mm. 



(Named for the Madeira River.) 



TETRAGONOPTERIX.E. 



Ctenobrycon rhabdops sp. nov. Fig. 10. 



Head 3f; depth 2; D. m, 9, i; A. iv, 46, i; P. i, 15; V. i, 7; 

 scales 49 in 1. 1. to caudal base and 2 more on latter; 12 scales above 

 1. 1.; 13 scales below 1. 1., to anal origin; 13 predorsal scales to 

 occipital process; head width 1| in its length; head depth at occiput 

 lyV; mandible 3; least depth of caudal peduncle 2|; first branched 

 anal ray 1|; pectoral lyV; ventral 1|; snout 4 in head measured 

 from upper jaw tip; eye 2|; maxillary 2f ; interorbital 2|. 



Body well compressed, general contour deeplj^ ovoid, with greatest 

 depth at dorsal origin, upper anterior profile concave-convex and 

 lower profile rather evenly convex. Predorsal and post ventral 

 with slight median keels, body edges otherwise evenly convex. 

 Caudal peduncle compressed, about long as deep. 



Head small, lower profile a little more inclined than upper, and 

 nearly flattened sides but slightly constricted towards lower surface. 

 36 



