20 BANGS — MAMMALS OF BLOCK ISLAND y Pe 
ern New England coast, and slightly different from mainland 
specimens. It, however, is not different enough to be recognized 
as a subspecies, and must be known as Peromyscus leucopus nove- 
boracensis (Fischer). The Microtus, which was much commoner 
than the Peromyscus on the island, and which I found chiefly in the 
marshy edges of the ponds, appears to be a very well-marked island 
form of the pennsylvanicus group, somewhat related to M. brewerr 
(Baird) of Muskeget Island, and not at all nearly to (the now 
extinct ?) M. nesophilus Bailey of Great Gull Island off the eastern 
extremity of Long Island. 
It may be characterized as follows: 
Microtus provectus sp. nov. 
Type, from Block Island, Rhode Island, middle-aged adult 2, no. 9794, 
Bangs coll., coll. Museum of Comparative Zodlogy, collected Aug. 5, 1899, 
by Outram Bangs. 
Characters.— Size rather larger than in true M. pennsylvanicus; colors 
similar to those of southeastern Massachusetts examples of M. pennsyl- 
vanicus, except that the belly is always gray. Skull peculiar, and much 
more like that of M. brewert than M. pennsylvanicus; interparietal very 
wide and extended far forward between parietals; nasals wide posteriorly 
and ending squarely — not rounding or pointed behind as in MZ. pennsyl- 
vanicus; audital bulle rather large. In old age the skull is longer and 
narrower than that of M. pennsylvanicus. 
From M. breweri the Block Island form can be told by much darker 
colors, normal pelage (not long and coarse), smaller size, smaller skull 
with less spoon-shaped nasals and wider interparietal. 
Color — Summer pelage. Whole upper parts yellowish bistre, some- 
what varied by dark brown tips to many of the hairs; tail indistinetly 
bicolor — dusky above, grayish below; feet and hands dusky brown; 
under parts clear gray, becoming whitish along middle of belly and 
between arms. 
1Specimens from the Cape Cod region of eastern Massachusetts and the 
islands of Martha’s Vineyard, Nantucket, etc., except of course Muskeget, 
where the very different M. breweri occurs, are rather different from true M. 
pennsylvanicus of the Middle States, being larger and much more reddish brown, 
the upper parts very often of a dull chestnut color, and the under parts usually 
much suffused with buffy or ochraceous shades. If this vole is considered, at 
any time, to represent a valid subspecies, it must bear, I think, the name Microtus 
pennsylvanicus rufidorsum (Baird), type locality, Holmes Hole, Martha’s Vineyard 
Island, Massachusetts. 
