MOKONB 321 



membrane; anal spines 3, not graduated; scales ctenoid. Two species, both 

 American, one inhabiting fresh waters of the Mississippi Valley and the other 

 brackish waters and the mouths of rivers of the Atlantic coast. 



MORONE INTERRUPTA GILL 



YELLOW BASS 

 (MAP CI) 



Gill, 1860, Proc. Ac. Nat. Sci. Phila., 118. 



J. & G. ( 530; M. V.,137; B., I, 127 (mississipiensis); J. & E., I, 1134; N., 36; J., 44; 

 F., 63 (Roccus); F. F., I. 3, 37; L., 29. 



Length 12 to 18 inches; body rather deep and compressed and back 

 elevated; profile angled at nape; depth 2.7 to 2.9; greatest width about 2 in 

 greatest depth; depth caudal peduncle 1.4 to 1.6 in its length. Ground color 

 olive-buff, with many small indistinct punctulations of emerald; alternate 

 rows of scales on sides with dark greenish to blackish central bands, these 

 adjoining to form prominent longitudinal stripes, 3 above lateral line, one 

 (which is more or less moniliform) coincident with it, and 3 or 4 below lateral 

 line; stripes below lateral line interrupted on posterior part of body, the 

 breaking point sometimes indicated by irregularly disposed black spots; 

 ventral region lighter than sides but of similar colors; vertical fins with 

 considerable bluish tinge; cheeks and opercles with bluish and emerald 

 iridescence; pupil pale dark blue; iris light greenish above pupil, darker out- 

 ward. Head subconic, pointed, 3 to 3.2 in length; width of head 2 to 2.1 in 

 its length; interorbital space little convex, 4 to 4.7; nose 3.1 to 3.7; mouth 

 terminal, slightly less oblique than in last species; maxillary barely to middle 

 of orbit, 2.6 to 2.8 in head; lower jaw not sensibly projecting; gill-rakers 

 longer than branchial filaments, X + 13 to 16. Dorsal IX-I, 12; longest 

 spine 1.6 in head; base of soft dorsal about 1.4 in base of spinous; caudal 

 forked; anal III, 10,' the spines not graduated, the first usually less than }/% 

 of second, the second and third of about equal length; ventrals % to vent; 

 pectorals 1.5 to 1.6. Scales 7, 51-55, 10-12, strongly ctenoid; lateral line 

 complete or nearly so, scarcely arched anteriorly, somewhat flexuose; cheeks 

 and opercles fully scaled, rows 12. 



This species is distributed in Illinois much like the white 

 bass, and although nearly twice as abundant in our collections as 

 that species, it comes everywhere from similar waters that is, 

 from the large rivers and adjacent lakes. It is primarily a lake 

 species, our one hundred and two collections giving us a fre- 

 quency coefficient of 3.16 for bottom-land lakes and sloughs, and 

 of 1.82 for rivers of the largest size. But two of these collections 

 were from creeks or the smaller rivers. We have found it, 

 like the preceding species, much more abundant in central Illi- 



