THE FISHES OF NEW JERSEY. 2777, 
and hyoid. Premaxillaries protractile. Maxillary with a supple- 
mental bone in large-mouthed forms, sometimes minute or obso- 
lete in others. Preopercle entire or somewhat serrate. Opercle 
ending in 2 flat points or prolonged in a black flap at angles. 
Preorbital short and deep. First suborbital narrow, maxillary 
not slipping under edge. Nostrils 2 on each side. Gill-mem- 
branes separate, free from isthmus. Gills 4, slit behind fourth. 
Gill-rakers variously formed, armed with small teeth. Pseudo- 
branchiz small, imperfect, almost glandular, nearly or quite cov- 
ered by skin. Branchiostegals 6, rarely 7. Lower pharyngeal 
bones separate, teeth conic or sometimes paved. Intestinal canal 
short. “Pylorie cocca 5 to 10. Vertebre 28 to 35 71(13,to 18 4-15 
to 17). Entopterygiod present. Precaudal or abdominal verte- 
bree with transverse processes from third or fourth to last. Ribs 
all but last 2 to 4 sessile, inserted on centrum behind transverse 
processes. Frontals with pair of large muciferous channels which 
converge posteriorly, or are confluent with a transverse channel 
connecting their posterior openings close together on median line 
in front of supraoccipital crest. Cheeks and opercles scaly. Body 
fully scaled, scales usually not strongly ctenoid, rarely cycloid. 
Lateral line present, usually complete. Dorsal fins confluent, 
spines VI to XIII in number, usually X, depressible in a shallow 
groove. Anal spines III to IX. Coloration usually brilliant, 
chiefly greenish. Sexes similar, changes with age often great. 
Fresh-water fishes of North America, forming one of the most 
characteristic features of our fish-fauna. Most of the species 
build nests which they defend with much courage. All are car- 
nivorous, voracious and gamy, and valued as food, their im- 
portance being in direct proportion to the size they attain. 
Key to the genera. 
a. Tongue and pterygoids with teeth; mouth large, maxillary reaching past 
middle of eye; scales cycloid; caudal convex. ACANTHARCHUS 
aa, Tongue and pterygoids toothless; mouth small, maxillary barely reaching 
past middle of eye. 
b. Caudal convex; opercle emarginate, without flap. 
c. Dorsal continuous, normally with IX spines; anal normally with 
III spines. ENNEACANTHUS 
cc. Dorsal angulated, some of median spines elevated, X; anal spines 
Te MESOGONISTIUS 
