20 BOOK OP THE BLACK BASS. 



strated that two perfectly distinct types of the genus were repre- 

 sented in most of the waters of the cismontane (east of the Rocky 

 Mountain) slope of the United States, except those of the New 

 England States and the Atlantic seaboard of the Middle States. In 

 limitation of this general statement it need only at present be re- 

 marked that but one of those types, the small-mouthed, appears to 

 have been an original inhabitant of the hydrographic basin of the 

 Ohio River. 



In order to obtain as clear and unprejudiced ideas as possible 

 respecting the species, the specimens from all the localities were in 

 the first place examined without reference to their names but only 

 with the view to ascertain their relations to each other. This ex- 

 amination confirmed the previous experience of the author for a 

 more limited range, and led to the combination of all into the two- 

 groups just referred to : between these many differences existed, 

 but none were discovered which permitted further definite sub- 

 division. The differences thus ascertained may be tabulated as 

 follows : 



Contrasted Differential Characteristics, 

 Small-Mouthed. Large-Mouthed. 



Scales of trunk 



Small {e. g. lat. line, 12-15; be- Moderate {e. g. lat. line, G5-70; 



tween lateral line, and back, 11 between lateral line and back, 

 rows). 1\ or 8 rows). 



Scales on nape and breast 



Much smaller than those of Scarcely (on nape), or not 



sides. much (on breast) smaller than 



those of sides. 



Scales of cheeJcs 



Minute (e. g., between orbit Moderately small (e. 7., between 



and preoperculum, about 17 rows orbit and preoperculum, about 10 



in an oblique line and about 9 rows in an oblique line and about 



in a horizontal one). 5-6 in a horizontal one). 



