FISH OF ONTARIO. 81 



two on each side. Gills four, a slit behind the fourth. Pseudobranchiae 

 small, almost glandular, nearly or quite covered by skin. Gill membranes 

 separate, free from the isthmus. Branchiostegals six, rarely seven. Gill 

 rakers variously formed, armed with small teeth, lower pharyngeal bones 

 separate, their teeth conic or sometimes paved. Cheeks and opercles scaly ; 

 body fully scaled, the scales usually strongly ctenoid, rarely cycloid ; 

 lateral line present, usually complete. Dorsal fins confluent, the spines 

 six to thirteen in number (usually ten), depressible in a shallow groove; 

 anal spines three to nine. Intestinal canal short. Pyloric caeca five to 

 ten. Vertebrae, twenty-eight to thirty-five. -Entopterygoid present. Pre- 

 caudal or abdominal vertebrae with transverse processes from the third or 

 fourth to the last ; ribs all but the last two to four, sessile, inserted on the 

 centrum behind the transverse processes. Frontals with a pair of large 

 muciferous channels which converge posteriorly or are confluent with a 

 transverse channel connecting the post frontals, their posterior openings 

 close together on the median line in front of the supraoccipital crest. 

 Colouration usually brilliant. 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 carnivorous, voracious and 

 gamy. All are valued as food, their importance being in direct proportion 

 to the size which they attain. 



GENUS POMOXIS. (GRASS BASS.) 



Body more or less elongate, strongly compressed, the snout project- 

 ing ; mouth large, oblique ; maxillary broad, with a well developed supple- 

 mental bone; teeth on vomer, palatines, entopterygoids and tongue; lower 

 pharyngeals narrow, with sharp teeth ; gill rakers4ong and slender, num- 

 erous ; opercle emarginate ; preopercle and preorbital finely serrated ; scales 

 large, feebly ctenoid ; fins large, the anal larger than dorsal, of six spines 

 and about seventeen rays ; dorsal with six to eight graduated spines, the 

 spinous dorsal shorter than the soft part ; caudal fin emarginate ; pectorals 

 rounded or obtusely pointed, with fifteen or sixteen rays, the upper long- 

 est ; ventrals close together, each with a strong spine ; branchiostegals 

 seven ; lateral line complete, the tubes straight and extending at least on 

 the anterior half of the exposed surface of the scale ; posterior processes 

 of the premaxillaries not extending to the frontals ; supraoccipital and 

 parietal crest very strong, produced forward on the frontals to between 

 the orbits; vertebrae, 18+15 = 33. 



(85) Crappie. Silver Bass. 



(Pomoxis annularis.) 



Body oblong, but more elongated than the next, the depth two-fifths 

 of the total length ; much compressed. Mouth oblique, larger than in the 



