CYPRINID^: — THE MINNOWS AND THE CARP 



101 



Opsopoeodus emilise . 

 Abramis crysoleucas 

 Notropis cayuga. . . . 



N. heterodon 



N. hudsonius 



80 



303 



30 



93 



147 



.59 



.17 



2.68 



.60 



TABLE VI 

 Geographical Groups, Illinois Minnows 



PREFERRING THE OHIO 

 DRAINAGE 



Notropis illecebrosus 

 Ericymba buccata 

 Hybopsis amblops 



PREFERRING THE MISSISSIPPI 

 DRAINAGE 



Chrosomus erythrogaster 

 Hybognathus nubila 

 Pimephales promelas 

 Notropis gillserti 

 N. hudsonius 

 N. lutrensis 



EVIDENTLY AVOIDING LOWER ILLINOISAN FREELT ENTERING LOWER ILLINOISAN 



GLACIATION GLACIATION 



Campostoma anomalum Hybognathus nuchalis 



Notropis blennius Pimephales notatus 



N. cornutus Abramis crysoleucas 



Ericymba buccata Cliola vigilax 



Hybopsis kentuckiensis Notropis whipplii 



N. atherinoides 

 N. rubrifrons 

 Hybopsis amblops 



The first table, relating to the twenty-four most abundant 

 species, shows the relative frequencies of occurrence of each 

 species in our collections from each class of situations indicated 

 by the headings of the columns. The figures of these columns, 

 called coefficients of frequency, when larger than 1 indicate a 

 greater than average frequency in the situation named, and, 

 when smaller than 1, a lesser frequency. That is to say, if all 

 the species of minnows had been equally and uniformly dis- 

 tributed through all classes of situations, the coefficients of this 

 table would all have been 1. Referring, for example, to Cam- 

 posto7na anomalum, in the first line of the table, it will be seen 

 that 195 of our collections contained this species. The number 

 of collections from larger rivers containing this minnow, as 

 shown by the figures in the second column of the table, were 



