62 BEVISIOX OF AMERICAN MOLES— TRUE. 



posterior lobe, wbicb ordinarily approacbes tbe anterior lobe in size, 

 may be wovu to a mere roniuled tubercle, connected witb anterior lobe 

 by an extremely narrow bridge. 



It is obvious from tbese facts that characters drawn from tbe shape 

 of worn teeth can be of little value in distinguishing- species. 



As regards external characters, it may be said that those individuals 

 in uhich the hairs of the tad and hind feet are brownish are young, 

 while those which have this hair white are mature or old. Old indi- 

 viduals often have in addition small tufts of entirely wiiite or whitish 

 fur mingled witb normal fur; but in some cases tbis appears to be 

 merely an individual peculiarity, and is not due to age. 



Very young moles appear to be much lighter and more silvery than 

 the adults. This appearance is heightened by the circumstance that 

 the fur (at least in dry skins) is closely ai)pressed and the surface color 

 is not clouded by intermixture with the dark color of tbe basal portion 

 of the hairs. 



SEASONAL DIFFERENCES IN COLOR IN SCAPANUS. 



Between the fresh winter and summer pelages there is not so much 

 diflerence in color as might be expected. The winter fur is usually 

 darker and grayer, while the summer fur is paler and has more of a 

 reddish tinge. Worn pelage is pale and faded and often suffused with 

 dull yellowish. There is uot^that sharpness of boundary between the 

 brown tips of the hairs and the plumbeous lower portion which exists 

 in new fur. In some instances, however, the old and new fur are so 

 closely alike in color that the boundary between them can only be 

 detected by the closest scrutiny. 



HISTORY OF THE SPECIES OF SCAPANUS. 



The occurrence of moles on the Pacific Coast was known to Lewis 

 and Clarke,' whose expedition was undertaken at the beginning of the 

 l)rcsent century, and i)erhaps to earlier explorers, but they were first 

 given a i)lace in scientific nomenclature by Richardson, in 1839,' who 

 called the si)ecies " Scalops canftdensis (Cuvier)." Cuvier did not really 

 use this Latin name for any species, but did apply its French equiv- 

 alent, '^Scalope du Canada,''^ to the Eastern mole, S. nquaUcus. Kich- 

 aidson supposed that the two moles were specifically the same, and 

 remarks : 



The Columbia animal {^Scapanus fownsendi] seems to be of larger dimensions, 

 and has a longer tail than the Shrew moles of the I'nited States [Scalops iKiiiaiiciin] ; 

 but I have not detected an»y other pecnliarities by which it might be characterized 

 as a distinct species.* 



'See the History of the Expedition of Lewis and Clarke, Paul Allen, editor, II, 

 1814, p. 178. 



-Kichardson, Fauna ISoreali Americana, Mammalia, 1829, p. 'J. 

 3R('gne Animal, 1st ed., I, 1817, p. 135. 

 ■* Richardson, loc. cit., i». 11. 



