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182 



MONOGRAPHS OP NORTH AMERICAN RODENTIA. 



Martha's Vineyard) I recently fou.id the su-calleH A. breweri excessively 

 nbuiidant. Thitfis the unly 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 nu;e.. From the peculiar character of the. 

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

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

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

 Miiskeget Anncola 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'." 



VVe 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 "brcweii" 

 in the texture of the pelage, the fur having the fame 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 inf'requency 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. 3669, 2525, 2524) marked 

 "edax"; is not appreciably diiTerent 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 "edox", with r 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 tl't rather grayer examples from the east. Of the two specimens 

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



'Tbi8 Hpeciuien \» litbeled, in the bandwritiD); of all of the lot received from imoi LeConle, 

 "tuuuUi Buoh., ripariiu DuK^y, noveioraccnnt Rioh., paluttnt Harlan". 



