CHARACINIDAE FROM VENEZUELA—SCHULTZ 239 
6a. No predorsal spine. 
7a. Supplementary scales, if present, small and confined to hinder edges 
of primary scales; anal fin with a basal sheath of scales and with 
highest rays anteriorly__._____._- Colossoma Higenmann (p. 255) 
76. Numerous supplementary scales which may obscure the primary 
ones; anal fin densely scaled in at least its basal half and with 
highest rays posteriorly or of nearly equal length posteriorly and 
anteriorly_______- Mylossoma Higenmann and Kennedy (p. 256) 
6b. A predorsal spine present; base of adipose fin less than half as long as 
that of rayed dorsal; dorsal with 22 rays or more; anterior teeth of 
outer series of premaxillary with an oblique cutting edge, not 
greatly compressed, generally more or less separated from those of 
RIMM OT SETI gms deus Wey al wy apulgel tn louleatoaany MBO daichii Myloplus Gill (p. 258) 
4b. Abdomen rounded or flattish or if keeled the median ridge lacking back- 
ward-directed points. 
8a. Both dorsal and anal origins in last third of standard length, body very 
elongate, narrow, with a pikelike mouth, belly rounded and having 
no keel; interorbital space flattish; pointed snout about as long as 
greatest depth of body; gill membranes extending far forward, free 
from each other and from isthmus; teeth conical, in a single row in 
both jaws; caudal fin forked (Ctenolucinae). 
9a. Numerous small, close-set, conical teeth in a single row, hooked back- 
ward on premaxillary, and meeting at tip of jaw to form a rounded 
expansion with somewhat enlarged teeth; 3-3 vomerine teeth oppo- 
site constricted portion of premaxillary; front sides of lower jaw 
with a barbellike flap of skin; anal origin under middle of dorsal 
base; dorsal origin almost equal distance from pelvic insertion to 
midcaudal base; last anal ray not filamentous; scales ctenoid. 
Ctenolucius Gill (p. 258) 
$b. Numerous small conical teeth in a single row, hooked backward, 
meeting at a point or acute angle behind projecting fleshy tip of 
snout; no vomerine teeth; no flap of skin at front of lower jaw; anal 
origin behind base of dorsal fin; dorsal origin 6 or 7 times closer to a 
vertical through pelvic origin than one through midcaudal base; 
last anal rays filamentous, at least in young; scales probably 
CY CLOLC Es ONN Any kak aya eran Uke. Boulengerella Higenmann (p. 261) 
8b. Dorsal or anal origins or both in middle third of standard length; snout 
not pikelike. 
10a. Numerous fine, incisorlike teeth on margins of lips, then a curved 
V-shaped row at front of both jaws; mouth protractile; scales 
rough; a conspicuous bispinous predorsal plate; a rather strong 
midventral ridge from pelvics to anus; interorbital convex; gill 
membranes joined, and narrowly joined to isthmus. 
Prochilodus Agassiz (p. 261) 
106. No fine teeth on margins of lips. 
lia. Gill membranes firmly joined to isthmus without a free fold across 
it and none of teeth canines; lateral line complete, straight; 
adipose fin present; caudal fin forked. 
12a. Fourth gill arch dilated behind; anterior side of fifth gill arch with 
its surface corrugated or plicated; each jaw with about 12 
feeble incisorlike teeth in fleshy lips; mouth not protractile, 
rather small, terminal; gill rakers minute. 
Chilodus Miller and Troschel (p. 265) 
