Allen.] 180 [December 15, 



tinent, which differs so markedly, both in faunal and floral, from the 

 Eastern Province. A great change in the fauna and flora is met with, 

 however, at the point of junction of the wooded and woodless regions 

 of the eastern half of the continent, which in the latitude of Iowa 

 occurs more than a hundred miles to the eastward of that State. At 

 this point as great and as abrupt a change occurs as usually takes 

 place between two contiguous faunal districts, one of which lies to 

 the north or to the south of the other, or where the line of division is 

 an isothermal one, separating different climatic and zoological zones. 

 A few only, if any, of the species embraced in this list seem to find 

 their eastern limit of distribution in this State ; but, with two or three 

 exceptions, they range through southern Wisconsin, Illinois, and even 

 into northwestern Indiana and southern Michigan, or to the eastern 

 limit of the prairies. Also, with very few exceptions, none are re- 

 stricted to it in either their northward or southward range. A few of 

 the more northern species, whose southern range is restricted to the 

 southern border of the Alleghanian fauna, may reach the northern 

 counties of Iowa, as a few essentially southern species may approach, 

 or even be found occasionally within its southern borders. Iowa is 

 hence mainly embraced within the Carolinian fauna, at least so far 

 as its mammals, birds and reptiles are concerned, though generally 

 heretofore supposed to belong, in great part, at least, to the Allegha- 

 nian. Among the strictly prairie mammals represented, are at least 

 four rodents (Spermophilus tridecem-Uneatus, S. Frankllnii, Geomys 

 bursarius, Hesperomys michiganensis) , two carnivores (Canis latrans, 

 Taxidea americana), and at least one insectivore (Scalops argent.atus). 

 Only one eastern species, the red squirrel (Sciurus hudsonius), ap- 

 pears to find at the prairie line its western limit, if, as some have 

 supposed, it be true that this animal does not range across the conti- 

 nent. 1 Hence the difference between the mammalian fauna of the 

 prairies of the Upper Mississippi valley and that of the forest region 

 to the eastward consists in the addition of a number of species pecu- 

 liar to the prairies. 



Since all the larger species of mammalia are everywhere rapidly 

 disappearing before the revolutionizing influences of civilization, and 

 since great and general changes occur in the faunal and floral features 

 of every country when brought under cultivation, it becomes a mat- 

 ter of unusual interest to preserve as correct a record as possible of 

 the primitive conditions of our own country in this respect, for com- 



1 See postea, p. 188. 



