114 TELEOSTEI : —- ACANTHOPTERI. — XX. 
minute or obsolete; preopercle entire or nearly so; preorbital deep, 
not sheathing the ‘maxillary ; gill membranes separate, free from 
isthmus ; pseudobranchize small, concealed. 3B. usually 6; lower 
pharyngeals separate; scales usually large; lateral line present. 
Dorsal continuous, with 6 to 13 spines; anal spines 3 to 8. Ver- 
tebre about 30. Intestines short, with a few ceca. Sexes similar, 
but the changes in form due to age often considerable. Genera 10; 
species about 25; carnivorous fishes especially characteristic of the 
Mississippi Valley, — all but one (Archoplites interruptus of Cal.) 
confined to the waters of the E. U.S. Some species build nests, 
and all are voracious and gamy. 
a. Dorsal fin scarcely larger than anal; gill rakers very long and slender. 
&. Spinous dorsal longer than soft, its spines 12; anal spines about 8. 
CENTRARCHUS, 149, 
6b. Spinous dorsal shorter than soft, with 6 to 8 spines; anal spines 6. 
Pomoxis, 150. 
aa. Dorsal fin much larger than anal; gill rakers shorter. 
c. Body comparatively short and deep, the depth usually more than 2 
the length; dorsal fin not deeply divided. 
d. Tongue and pterygoids with teeth; mouth large (the maxillary 
reaching past middle of eye). 
ce. Scales ctenoid; caudal concave behind. 
J. Opercle Paes behind; anal spines usually 6; branchios- 
tegals 6... . - fs ey andl FBO a AMBLOPLITES, 161. 
Jf. Opercle ending in a black convex process or flap; anal spines 3. 
CHANOBRYTTUS, 152. 
ee. Scales cycloid; caudal convex. . . . ACANTHARCHUS, 153. 
dd, Tongue and pterygoids toothless; mouth small (the maxillary barely 
to middle of eye). 
g- Caudal convex; opercle emarginate, without flap. 
h. Dorsal fin continuous, normally with 9 spines; anal nor- 
mally with 8 spines. . . . . ENNEACANTHUS, 154. 
kh. Dorsal fin angulated, some of the median spines elevated; 
dorsal spines 10; anal 3. . . . Mersoconistivs, 155. 
gg- Caudal margin concave; opercle prolonged behind in a con- 
vex process or flap which is always black; dorsal spines 
normally 10; anal3. . . . + ‘Lzroms, 156. 
ec. Body comparatively elongate, the depth i in ‘adult about 4 the length; 
D. low, deeply emarginate, with 10 spines; mouth large; C. Iunate. 
Microprervs, 157. 
149. CENTRARCHUS Cuv. & Val. (xévrpov, spine ; 
dpxos, anus.) 
297. C. macropterus Lacépéde. Body ovate; fins high. Green, 
with rows of dark brown spots along sides ; fins reticulated; young 
with a black ocellus on D. bebind. Head 31; depth 2. Scales 
5-44-14. D. XI or X11, 12. A. VIlor VIIL15. L.6. N.C 
to Ill, and S., in lowland streams. (jaxpés, long; arepdy, fin.) 
