THE FISHES OF NEW JERSEY. 2yj 



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- 

 branchiae small, imperfect, almost glandular, nearly or c[uite cov- 

 ered by skin. Branchiostegals 6, rarely 7. Lower pharyngeal 

 bones separate, teeth conic or sometimes paved. Intestinal canal 

 short. Pyloric cceca 5 to 10. Vertebra 28 to 35 (13 to 18 -f 15 

 to 17). Entopterygiod present. Precaudal or abdominal verte- 

 brae 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. acaxtharchus 



na. Tongue and pterygoids toothless ; mouth small, maxillary barely reaching 

 past middle of eye. 

 h. Caudal convex ; opercle emarginate, without flap. 



c. Dorsal continuous, normally with IX spines ; anal normally with 



III spines. Enneacaxthus 



cc. Dorsal angulated, some of median spines elevated, X ; anal spines 



III. MESOGONISTIUS 



