Eigenmann: The Serrasalmin.e and Mylin.^. 249 



the head. D. 15; A. 32-33; abdominal serra; 31-35; head 3; depth 

 2.66; eye 5 in the head, 2 in interorbital; profile nearly straight; 

 lateral line 100; predorsal line naked; a dark humeral spot; sides with 

 dark spots; back sometimes with parallel bands; dorsal, anal, and 



adipose with light base and dark margin elongatus Kner. 15. 



bb. Snout blunt, about equal to the eye in length; D. 16; A. 30; abdominal 

 serrae about 27; head 3.2; eye 4 in the head; profile but slightly con- 

 cave. Caudal with a dark margin gibbus Castelnau. 16. 



bbb. Snout not very blunt, longer than eye; one-third of cheeks naked in the 

 types; D.i6; A. 32; serrae 37. Caudal with a light margin. 



hoUandi Eigenmann. 17. 

 aa. Depth 2 or less than 2 in the length, rarely 2.1 or 2.33 in humeralis gracilior. 



c. Caudal with a submarginal black band, the margin hyaline; interorbital 

 2.5 in the length of the head; snout blunt. 



d. Depth 1.6 to end of lateral line; bright yellow; a humeral shade, 



otherwise unspotted asopus Cope. 18. 



dd. Depth i. 75-1. 92; sides spotted spilopleiira Kner. 19. 



cc. Caudal in adult with a marginal black band; anal with a dusky margin. 



e. Snout blunt; interorbital 2.33-2.5 in the length of the head (nearly 3 



in small specimens); margin of second suborbital convex. 

 /. Snout shorter than the eye; interorbital 2.5 in the head, even in 

 specimens but 120 mm. long. Depth 1.8-1.9; D. 15 or 17; 

 A. 31-33; serrae 31-34; cheeks entirely or nearly entirely 

 covered; lower jaw heavy. (Palatine teeth sometimes want- 

 ing?) maculalus Kner. 20. 



{ff. Snout shorter than eye; interorbital 2.4 in the head. Depth 

 1.7; D. 17; A. 32; serrae 33; cheeks with a wide naked area; 

 lower jaw not very heavy; palate with teeth? See Prislo- 

 brycon scapularis and calmoni.) 

 fff. Snout longer than eye; D. 16 or 17 rarely 19; A. 31-36; serrae, 

 rarely 28 or 36; lateral line 87-91; depth 1.8-2. 



rhombeus Linnaeus. 21. 



ffff. Snout longer than eye; interorbital 2.8-nearly 3 in the length 



of the head; D. 15 or 16; A. 32-33; serrae 30-31; depth 1.8; 



head 3-3.2. Snout about 3 in the length of the head; eye 



5-5.4; second suborbital leaving but a narrow naked strip 



below para'ense Steindachner. 22. 



ee. Snout more acute; head compressed, interorbital 3 or more in the 

 length of the head (3 in the largest). 

 g. Anal slightly falcate, the third ray heavy; second suborbital 

 more or less truncate, leaving a wider naked space than in 

 rhombeus or brandtii; ventral serrae very strong, 26-33, most 

 frequently 30; depth 2, rarely 1.7; D- 15-18. usually 17; 

 A. 32-36, usually 33 or 34- 



humeralis Cuvier & Valenciennes. 23. 



gg. Characters of humeralis but the depth 2.33 in the length to end 



of lateral line gracilior Eigenmann. 24. 



