182 MONOGRAPHS OF NORTH AMERICAN KODENTIA. 



Martha's Vineyard) 1 recently found the so-called A. breweri excessively 

 abundant. This is the only locality from which this supposed species has 

 been reported. They are generally much paler in color than the riparius of 



the interior, and though not differing from them appreciably in other respects, 

 they form an interesting insular race. From the peculiar character of the 

 locality, the scattered beach grass growing upon it affording but slight pro- 

 tection from the sunlight, the intensity of which is greatly heightened by the 

 almost bare, light-colored sands, the generally bleached appearance of the 

 Muskeget Anricola might have been anticipated. Specimens occasionally 

 occur of nearly the ordinary color, or which are undistingiiishable from the 

 lighter-colored specimens from the interior: but most of them seem to be 

 quite like the ones described by Professor Baird. The mice living in the exten- 

 sive sand dunes at Ipswich under circumstances similar to those of the Mus- 

 keget mice, often present the half white appearance of A. 'breweri'." 



We were at first inclined to regard "breweri" as an isolated case of 

 riparius ; but the facts of the Ipswich mice, as given by Mr. Allen, and some 

 intermediate specimens before us, show such a gradation that we cannot draw 

 any line. Thus, No. 4713 (unlabeled as to locality) is much grayer than aver- 

 age riparius, but not quite up to "breweri". It likewise resembles "breweri" 

 in the texture of the pelage, the fur having the same coarse, harsh, lustreless 

 character. Now, this style of fur is enumerated among the features of A. 

 "edax", and characterizes all the specimens from the southern and lower parts 

 of California, where the infrequency of rain diminishes or altogether precludes 

 forest-growth, and places the animals under conditions similar to those of 

 Muskeget. An unregistered specimen* of LeConte's from the Eastern United 

 States, undistingiiishable from No. 4713, is absolutely identical, in color and 

 text ure of fur, with several Californian skins (as Nos. 3669, 2525, 2524) marked 

 "edax"; is not appreciably different from LeConte's type of "edax", nor from 

 Nebraska (as No. 43 1 8) and Utah (as No. 3350) specimens. The type of "cali- 

 fornicus" combines the loose, coarse pelage of "edax", with a rufescent hue 

 approaching "occidentalis". Specimens of supposed "montana" and the type 

 of "longirostris" are precisely matched in the color and texture of the fur 

 with any of the rather grayer examples from the east. Of the two specimens 

 referred (one with a query) to "A. modesta", one, tue type, No. fVW, is much 



"This specimen is labeled, in the handwriting of all of the lot received from Major LeConte, 

 "nasutut Bach., riparius DeKay, noveboraccnuis Rich., palustris Harlan". 



