182 MONOGRAPHS OF NORTH AMERICAN RODENTIA. 
Martha’s Vineyard) I 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 Armcola might have been anticipated. Specimens occasionally 
occur of nearly the ordinary color, or which are undistinguishable 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, undistinguishable from No, 4713, is absolutely identical, in color and 
texture of fur, with several Californian skins (as Nos. 8669, 2525, 2524) marked 
“edax”; is not appreciably different from LeConte’s type of ‘edax”, nor from 
Nebraska (as No. 4318) and Utah (as No. 3350) specimens. The type of “cali- 
fornicus” combines the loose, coarse pelage of ‘‘edax”, with a rufeseent 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, the type, No. 775, is much 
ba 
*This specimen is labeled, in the handwriting of all of the lot received from Major LeConte, 
“nasutus Bach., riparius DeKay, noveboracensis Rich., palustris Harlan”. 
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