110 Proceedings of the Biological Society of Washington. 



There is no indication of any intergradation in color pattern except in 

 specimens coming from the immediate vicinity of Lake Traverse and of 

 Big Stone Lake on the boundary between Minnesota and the Dakotas. 



Almost all the Leopard Frogs from a region perhaps one hundred miles 

 north and south along the boundary between Minnesota on the east and 

 N«rth and South Dakota on the west show more or less plainly a tendency 

 to intergrade with the species under discussion. In fact, there seem to be 

 more specimens with typical coloration of Rana kandiyohi than with that 

 of Rana pipiens. 



The taxonomic value of this variation can not be well understood until 

 the frogs of the region west of Big Stone Lake can be critically studied. 

 From the data already at hand we may suppose Rana kandiyohi to be a form 

 developed along the upper course of the Minnesota River, either as a vari- 

 ant of Rana pipiens or as a result of hybridization with some other form. 



If this species is only a variant of Rana pipiens, produced by some 

 ecologic factor, we may expect to find it more common a little farther west, 

 or perhaps even supplanting the latter species at the western limit of the 

 range of frogs in the arid belt. 



The name Rana kandiyohi is proposed with some misgivings because of 

 the small knowledge we have of the form and its relation to other frogs and 

 to its environment. Localities from which we have received it are, with 

 one exception, in the southwest quarter of Minnesota. The other record is 

 barely across the state line in South Dakota. It is to be hoped that careful 

 field studies may be made of the frogs of the region within a hundred miles 

 of Big Stone Lake in order that ecologic studies may supplement our present 

 knowledge of the group. 



In conclusion, it may be well to mention that males of Rana kandiyohi 

 kept alive in the aquarium have been croaking vigorously for some weeks 

 and that their note is quite distinct from that of some Rana pipiens from 

 the vicinity of Chicago. The note of the Leopard Frog is more or less a 

 succession of syllables and may be almost represented by striking stones 

 together rather rapidly. That of Rana kandiyohi is more in the nature of a 

 croak and might be represented by grinding two stones together under con- 

 siderable pressure. 



