20 I500K OF THE BLACK BASS. 



stratcd tliat two perfectly distinct types of the genus were repre- 

 sented in most of the waters of the cisjnontane (east of the Eocky 

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

 England States and the Atlantic seaboard of tlie IMiddle States. In 

 limitation of this general stateinent 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 nn|)rcju(liced ideas as possible 

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

 the first plac3 examined without reference to their names but only 

 Avith 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 differcJiccs thus ascertained may be tabulated as 

 follows : 



Contrasted Differential Characteristics, 

 Small-Mouthed. Large-Mouthkd. 



Scales of tninh 



Small (e. g. lat. line, 72-75; be- ^Tod crate {c. g. lat. line, G5-70; 



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

 rows). 7;^ or 8 rows). 



'Scales on nape and breast 

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



sides. much (on breast) smaller than 



tliose of sides. 



Scales of (Jiccks 



Minute {e. cj., between orl)it ISlodorately smalUcr/.jH'tween 



and preoi)erculum, about 17 rows orbit and i)reo|)erculuni, about 10 



in an obliciuc. line and about 9 rows in an obli(iue^ine and about 



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



