440 W. F. BLAIR 



and Microtus pennsylvanicus , along with various species and genera 

 that occur in southwestern Kansas today and some highly euryther- 

 mal forms. 



Another fauna from the same general area is of extreme interest 

 because it includes a number of fishes (Smith, 1954). This fauna, 

 from Beaver County, Oklahoma, is regarded as Illinoian in age. 

 Along with species of presently wide distribution, it includes such 

 northern species as the muskellunge {Esox miisquinongy) and yellow 

 perch {Perca flavescens) , both of which have southern limits today 

 several hundred miles to the northeast. Spruce, fir, and pine pollens 

 were found in the deposits from which the fossils were taken. Mam- 

 mals listed in this fauna include the northern species Sorex cinereus 

 and Microtus pennsylvanicus and a few types that occur in the 

 region today. 



Other faunas from this same region are regarded as Interglacial, 

 and are dominated by mammals of generally southern affinities 

 (Hibbard, 1949, 1955b). When considered along with the cool- 

 climate faunas, they indicate recurrent major climatic shifts in 

 the region. 



The Conard Fissure fauna of northwestern Arkansas (described 

 by Barnum Brown and listed by Hay (1924), who regarded it as 

 possibly Illinoian in age) includes a number of mammals that occur 

 today considerably farther north, or have their closest relatives 

 there. These are: the red squirrel {Sciurus hudsonicus), which now 

 ranges south to southern Iowa; the porcupine {Erethizon dorsatum), 

 which now ranges south to central Wisconsin in the central states, 

 but is widely distributed in mountains of the west; the snowshoe 

 hare {Lepus americanus), which now reaches a present southern 

 limit in the central United States similar to that of the porcupine; 

 the masked shrew {Sorex cinereus) and the pigmy shrew {Micro- 

 sorex), which now range south to northern Iowa; the fisher (Martes 

 pennanti) , which now occurs north of the Great Lakes ; and the least 

 weasel (Mustela erminea), which now ranges south to southern 

 Nebraska. The extinct muskox (Symbos) is also represented. 



Another cave fauna from much farther south includes a similar 

 representation of cold-adapted mammals. This is the Burnet Cave 

 fauna of the Guadalupe Mountains, New Mexico. As listed by Mur- 

 ray (1957) this assemblage includes various species that occur in the 

 region today and several of presently more northern distribution. 



