From the Eastern United States. 61 



3.4 inches ; tail, 2.7 "-which were taken from an alcoholic spec- 

 imen. 



The next name to be examined is the Hesperomys gracilis of 

 Le Conte (Proc. Acad. Nat. Sci. Phila., vn, 1855, 442). Le Conte 

 states that the animal " inhabits Michigan; Professor Baird." 

 From the description, " dark slate color above, a little tipped 

 with brown," it seems probable that the type specimen was 

 immature. There are some discrepancies between the measure- 

 ments given in the original description and those of the same 

 specimen given by Baird (Mam. N. Am., 1857, 473). Accord- 

 ing to Le Conte, the length (head and body) is 3.8 inches ; tail, 4, 

 while Baird gives the dimensions of the same parts as 3.60 and 

 3.70 inches respectively. The latter author adds that the body is 

 stretched. The long tail of this specimen might suggest the pos- 

 sibility of its being the same as my canadensis, but on account 

 of its poor condition and the vagueness of the description, it 

 seems wisest to discard the name entirely as undeterminable. 

 Moreover, Baird states that the pencil of the type is 0.10 in. 

 (2.5 mm.) in length, which is much less than in any specimens 

 of 8. canadensis that I have seen. 



While not wishing to enter here into a general discussion of the 

 relationships of Mus michiyanensis Aud. and Bach., and Mm bairdii 

 Hoy and Kennicott, a few words concerning the probable bear- 

 ing of these animals on the present case may not be out 

 of place. Mas michiganensis, from Erie county, Michigan, is 

 described (Journ. Acad. Nat. Sci. Phila, VIII, pt. n, 1842, 304) 

 as -a "mouse with yellow cheeks, a light grayish-brown color 

 above, whitish below. * * * The feet, nails, ears, and tail 

 are light brown." It is farther remarked that "there is no dis- 

 tinct line of demarkation between the colors of the back and 

 under surface, nor does the white extend along the sides as in 

 the white-footed mouse. Dimensions : length of head and body, 

 4 inches lines ; length of tail, 2 inches 6 lines." That this 

 animal cannot be the same as S. canadensis is shown by the short 

 tail and peculiar coloring of the feet and sides. 



The description of Mus bairdii (Rep. Com. Patents for the year 

 1856, published in 1857, p. 92) from northern Illinois and south- 

 ern Wisconsin refers to some short-tailed, bright-colored mouse, 

 (mite unlike Sitomys a. canadensis, as the following extracts will 

 show : " Length of the adult male, from nose to root of tail, 2i 

 inches ; tail (vertebrae), II inches ; hind foot, f of an inch. Head 



