268 Fretp Museum or Naturat History — Zod oey, Vor. X. 
ij. 
hh. 
&8- 
KEY TO THE GENERA. 
Caudal fin forked; adipose fin present (except in Phanagoniates). 
Scales cycloid. 
Teeth wanting. (Curimatine) Curimatus, p. 269. 
Teeth in lower jaw wanting. (Parodontine) Apareiodon, p. 270. 
. Teeth present in both jaws. 
Teeth in a single series in each jaw; lateral line incomplete. 
(Chetrodontine) 
Adipose fin wanting; anal fin long, with more than 4o rays. 
Phanagoniates, p. 272. 
Adipose fin present; anal fin short, with fewer than 30 rays. 
Lower half of base of caudal in the male with a peculiar lobe of 
enlarged scales. Compsura, p. 273. 
No enlarged scales on base of caudal. 
Pseudochetrodon gen. nov., p. 275. 
Teeth in upper jaw in 2 series, those in lower jaw in a single 
series. (Tetragonopterine) 
The thoracic region not greatly dilated or compressed. 
Lateral line complete 
Dorsal fin inserted far back, its origin nearer caudal than eye, 
notably behind origin of anal. Gephyrocharax, p. 277. 
Dorsal fin inserted over or in advance of anal. 
Maxillary with few or no teeth; caudal spot if present not 
extended on middle caudal rays. 
Second suborbital narrow, leaving a naked triangular area below 
suture between the first and second suborbitals; first series of 
premaxillary teeth regularly placed. Astyanax, p. 279. 
Second suborbital expanded, covering nearly the entire cheek, 
not leaving a naked triangle below suture between the first and 
second suborbitals; first series of premaxillary teeth more or 
less irregularly placed. Bryconamericus, p. 282. 
Maxillary in adult with from 5 to 25 teeth; the inner caudal rays 
black. Hemibrycon, p. 285. 
Lateral line incomplete; no caudal spot. 
Hyphessobrycon, p. 286. 
The thoracic region greatly compressed, dialated, forming a 
semicircular disc. (Gasteropelecine) Thoracocharax, p. 287. 
ddd. Premaxillary teeth in 3 series; teeth in mandible in 1 or 2 series, 
if with 2 series, the outer one composed of only 2 teeth on edge 
of jaw and directed forward. 
Anal fin short, with not more than 17 rays; body long, little 
compressed. (Tetragonoptrine) Creagrutus, p. 289. 
