KEY TO GENERA—PERCIDA. 87 
Family; PERCIDAs. 
vey to Genera. 
A. Pseudobmanchiz well developed; preopercle serrate; branchiostegals 7; no anal 
papilla. 
B. Canine teeth on jaws and palatines; body elongate; ventral fins well sepa- 
rated.— STIZOSTEDION. 
BB. Canine teeth none ; body oblong, ventral fins near together.— PERCA. 
AA. Pseudobranchize imperfect or wanting ; preopercle entire or nearly so; branchios- 
tegals 6; anal papilla usually present. 
Cc. Parietal region of skull depressed, not strongly convex in transverse section, 
—-shaped in section. 
D. Cranium broad between the eyes, snout conic, projecting pig-like beyond 
the inferior mouth.— PERCINA. 
DD. Cranium not broad between the eyes, snout not much proj-_cting. 
E. Body not hyaline nor extremely elongate, its surface almost en- 
tirely covered with scales. 
F. Premaxillaries not protractile, the skin of the premaxillary 
continuous in the middle with that of the forehead with no 
cross groove between.— HADROPTERUS. 
FF. Premaxillaries protractile (in Cot/fogaster shumardi a narrow, 
connecting frenum sometimes crosses from the premaxillary 
to the forehead). 
G. Anal spines 2, both well developed, the first usually the 
longer. : 
H. Mid-line of belly naked or covered by caducous 
shields ; gill membranes scarcely conne ted — 
COTTOGASTER. 
HH. Belly covered with ordinary scales; gill mem- 
branes broadly connected.— DIPLESION. 
GG. Anal spine single, obscure; anal fin small, much shorter 
than soft dorsal.— BOLEOSOMA. 
EE. Body extremely elongate, hyaline, subterete, the belly mostly 
naked. 
ie Premaxillaries not protractile ; dorsal spines 12 or 13.— 
CRYSTALLARIA., 
II. Premaxillaries protractile ; dorsal spines 9 to 11.— 
AMMOCRYPTA. 
Cc. Parietal region of skull not depressed, more or less strongly convex in cross- 
section, N-shaped; premaxillaries never protractile; belly covered with 
ordinary scales. 
Jie Lateral line sfraight ; body rather robust.— ETHEOSTOMA. 
JJ. lateral line with a slight arch running high anteriorly ; body slender.— 
BOLEICHTHYS. 
