Jordan and Evermann. Fishes of North America. 1395 



mm. Skull firm, not excessively cavernous, interorbital 

 space less broad ; preorbital not turgid ; soft dorsal 

 of less than 30 rays. 



o. Scales of the lateral line considerably enlarged, 

 almost entirely concealed by smaller ones; 

 anal fin small, inserted well forward its first 

 spine usually as near ventrals as caudal ; cau- 

 dal fin pointed, its peduncle long and slender ; 

 soft dorsal and anal scaly ; scales small ; pre- 

 operclo without bony serra 1 ; pseudobranchire 

 small, often obsolete on one side. (Fluviatilo 

 species.) PLAGIOSCION, 575. 



oo. Scales of the lateral line similar to the others, not 

 concealed by smaller ones; anal fin inserted 

 more or less posteriorly, first spine usually 

 nearer caudal than ventrals ; caudal peduncle 

 rather short ; pseudobranchije well developed. 

 2>. Head not very broad, the interorbital space 

 not notably spongy nor deeply cavernous. 

 q. Preopercle with its membranaceous 

 edge entire, crenulate or ciliate, 

 with no bony teeth ; teeth in lower 

 jaw in few series. 



r. Teeth very small, equal, uniserial 

 or very nearly so; snout very 

 short; cleft of mouth oblique or 

 oven vertical, the lower jaw 

 projecting. LARIMUS, 576. 



rr. Teeth larger, moie or less un- 

 equal, those of the lower jaw 

 in one or two series or in 

 bands ; cleft of mouth not ver- 

 tical. 



s. Upper jaw with some of the 

 teeth enlarged, forming 

 canines ; some canines in 

 lower jaw; lower jaw 

 projecting. 



ODONTOSCION, 577. 

 ss. Upper jaw with a narrow 

 band of teeth, those of 

 the outer row more or 

 less enlarged; no distinct 

 canines. CORVULA, 578. 

 qq. Preopercle with its bony margin arm- 

 ed with sharp teeth or serrse. 

 t. Preopercle with its lowermost 

 spino directed abruptly down- 

 ward ; soft dorsal and anal fin 

 moderately scaly. 

 u.' Lower jaw with a few slen- 

 der canines ; second anal 

 spine very small. 



ELATTARCHUS, 579. 

 uu. Lower jaw without canines ; 

 second anal spine mod- 

 erate or large. 



BAIRDIELLA, 580. 



