148 BULLETIN OF THE 



other?, particularly of the genera Arvicola and Blarina, currently re- 

 ceived as valid, are here treated as merely nominal. While our reasons 

 therefor are given somewhat fully in their proper connection, a few 

 general remarks in further explanation seem called for here. 



In the present greatly increased state of our knowledge of American 

 mammals, not a few characters once very naturally considered of great 

 importance in a specific diagnosis are to he regarded as far from de- 

 cisive, they now being known to he dependent either upon age, season, 

 or locality, or to be mere individual variations. A difference in size, 

 for instance, is at present well known in mammals, as well as in birds, 

 to almost universally accompany differences in the latitude and elevation 

 of their respective habitats, the southern representatives of species widely 

 diffused being very appreciably smaller than the northern. The differ- 

 ence between the extremes amounts not unfrequently to nearly one 

 fourth, and occasionally even to one third, of the average size, so that, 

 considered apart from the connecting stages afforded by representatives 

 from the intervening districts, they might well be regarded as belonging 

 to distinct species. It is also now well known that mammals vary 

 geographically in respect to color, though not yet fully to what extent, 

 and also in the character of the pelage. These latter facts have been 

 long recognized practically in respect to the fur-bearing species, but it 

 appears equally true of most of the others. Experienced trappers and 

 fur-dealers readily distinguish the Mink and Sable skins of the north 

 from those of the south, by the comparatively greater fineness, density, 

 and length of the fur of the northern animal ;* similar differences are 

 equally evident in the pelage of the Wolves, Foxes, Lynxes, and Hares. 

 This difference is similar to that observable between winter and summer 

 specimens from the same locality, the northern corresponding in the 

 character Of the pelage to the winter and the southern to the summer 

 ones. The resemblance is perhaps still more striking in regard to the 



ticularly among the Hymenoptera, Neuroptera, ami Coleoptera, and not :\ few are 

 regarded as primitively almost cosmopolitan. The same is true in regard to plants, 

 quite a large proportion of the species of the northern North American flora being con- 

 sidered identical with European and Asiatic. Hence we naturally inquire, Is there 

 really this discrepancy in the distribution of species in the different classes of organized 

 beings only apparent through the biased opinions of one or the other of these 



schoi ' i ■ its? 



* In the case of the Minks, those of the prairies are distinguished as readily from those 

 inhabiting the adjoining wooded districts, the former having coarser and browner fur, 

 the difference being sufficient to materially affect their price in the market. 



