286 



specimens having these numbers in both lakes. The range of variation is two 

 greater in Turkey Lake, from 12 to 18 as compared from 14 to IS in Tippecanoe 

 Lake. This again may be due to the greater number of specimens. 



60 

 50 

 40 

 30 

 20 

 10 



12 13 14 15 16 17 (8 



Fig. 4. 



TABLE V. 



Eh a 



? 2.^ 



fo 



of specimens having 

 of specimens having 

 of specimens having 

 of specimens having 

 of specimens having 

 of specimens having 



Per cent. 

 Per cent. 

 Per cent. 

 Per cent. 

 Per cent. 

 Per cent. 

 Per cent, of specimens bavin 



12 dorsal rays 



13 dorsal rays 



14 dorsal rays 



15 dorsal rays 



16 dorsal rays 



17 dorsal rays 



18 dorsal ravs 



Table VI presents all the combinations of dorsal spines and dorsal rays from 

 both lakes. The spines are represented by Roman numbers and the rays by 

 Arabic numbers. The commonest combination in Turkey Lake is J^IY-15 and 

 XV-1.5; XIV, XV, occurring most frequently in the spinous dorsal, and 15 most 

 frequently in the soft dorsal. The per cent, of specimens having these combina- 

 tions is 22.46 and 24.49 respectively. In Tippecanoe Lake, XIV-16 is the com- 

 monest combination, XIV being the prevailing number in the spinous dorsal and 

 16 in the soft dorsal. 32.11 per cent, of the specimens have this combination. 



