MURID^E— SIGMODONTES— HESPEEOMYS I\1 IC11IGANENSIS. 95 



to the prairie"; that is to say, the differences detailed by these authors are 

 simply and exactly dependent upon whether the animal lives in woodland or 

 in prairie. 



As will he seen by the table below, H. michiganensis is much smaller 

 than leucopus, averaging under three inches long (2.95), and only exception- 

 ally, in extreme cases, reaching the average dimensions (3^) of leucopus. 

 Some adult examples, indeed, are hardly over 2J in length. The next most 

 conspicuous feature is the uniformly shorter tail, both relatively and absolutely. 

 With an average of just two inches, it ranges from 1§, or a little less, to 2^, 

 but is hardly ever over 2^, and not very often below 2. In general, it about 

 equals the head without the trunk, having, therefore, much the same relative 

 strength as in H. var. sonoriensis. The smallness of the feet is equally 

 marked and characteristic. The very largest hind feet do not exceed 0.75, 

 which is below the average of leucopus ; they range between 0.65 and 0.75, 

 settling at 0.69 for the. mean size. As it is rare for the smallest foot of leu- 

 copus to drop to 0.75, this feature alone gives indications by which probably 

 nineteen specimens of every twenty could be identified. The ears are notice- 

 ably short and small every way ; usually under 0.50 high, they run from 0.40 

 to 0.50, only very rarely surpassing the latter figure. 



The coloration is almost equally distinctive in its uniform darkness. Most 

 of the specimens come nearest to "austerus" in this respect. The dark color 

 almost always* extends on both feet to the digits, whereas in leucopus the feet 

 are (usually) white. The shade is difficult to name, but may be called a mix- 

 ture of gray and yellowish-brown on the sides, passing along the middle line 

 of the body above, from nose to tail, as a broad stripe, into blackish-brown. 

 The under parts are snow-white. The tail is always distinctly bicolor, and 

 usually sharply so, but sometimes the under surface is brownish-white. The 

 ears are blackish, usually without the slightest pale edging. The whiskers 

 are light and dark, and the longer ones exceed the head 



This animal is stated to have six mammae — four abdominal and two pec- 

 toral. The label upon one of Mr. Kennicott's infant specimens says, "five 

 found together." On the label of another of his, he states that "two old ones, 

 with three young, were found in a rail-fence on the prairie." 



Aside from the cjuestion of "bairdii", which must be summarily disposed 



* A Kansas specimen, which I refer to this species, forwarded for examination by Prof. F. H. Snow, 

 presents the exceptional feature of nearly white feet ; the dusky color of the legs only reaching a little 

 way past the ankle, and not at all beyond the wrist. 



