5 
The manuscript was edited by O. F. Glissendorf, number (14) of darter species, of which P. sciera is 
chnical editor at the Survey. Edward C. Raney, the most abundant. 
ornell University, served as special guest reviewer. The Embarras River, a tributary of the Wabash, has 
its headwaters in Champaign County and meanders 
THE STUDY AREA southward through rich farmland on Wisconsin glacial 
till until it cuts through the Shelbyville Moraine near 
Charleston in Coles County. For several miles down- 
stream from Charleston the river has deposited large 
quantities of glacial gravel from the thick morainal 
deposits. Near Newton in Jasper County it veers 
The area selected for study was the middle Em- 
uras River in the vicinity of Greenup, Cumberland 
o., Illinois. Less disturbed than most other local 
reams, the Embarras supports an exceptionally large 
Fig. 1. — Distribution of Percina sciera in Mlinois and adjacent Indiana and Missouri and the total range (inset) of the 
“Ss. Some of the Indiana records are from Gerking (1945 :85). On the Illinois map the study area Is encircled (at heaviest 
T Of dots); on the inset map vertical hatching represents the range of P. s. sciera, horizontal hatching that of P. s. apristis. 
