PROCEEDINGS V^ I.

Vol. XIX, ^pp. 71-72

May

_1, 1906

PROCEEDINGS

OF TIIK

BIOLOGICAL SOCIETY OF WASHINGTON

C:

^{I ! P,}

V^

^I.

A NEW ^VOLE FROM MONTAGUE ISLAND, ALASKA^r>,/'*AS- BY WILFRED

^H.

OSGOOD.

"

During

^{a short}

time spent on Montague

Island,

Alaska,

ⁱⁿ the

spring

^{of lOOo,}

Mr.

Oliarles

Sheldon, although

chiefly inter- ested in large hears,

found time

to

"

Ijotherwith

mousetraps."

As

a result of this interest in

small mammals

as well as_large,

seven specimens

^{of a vole}

and two

of a

shrew, prepared and presented hy Mr. Sheldon,

^are

now

in the Biological

Survey

Collection.

The shrews appear

^to

be

indistinguishable

from

the species ^of the

adjacent mainland

coast (Sorex obscurus alascensis),

but

the voles differ so

widely

^{as to} require

a new name. For

the privilege ^of describing ^this

new _form,

I

am

in-

debted

to

Dr.

C.

Hart Merriam, ^Chief

^of the Biological

Survey.

Microtus elymocetes*

sp.nov.

Ti/pe from the east side of

Montague

Island, Prince William Sound, Alaska. No.137,323,U.S.National

Museum,

BiologicalSurveyCollection,

c? adult.

May

^{12,1905. C.Sheldon.}

Charnder.t.

—

_Sizevery

large,onlyequalled

among

^theAlaskan

^members

of the^"_operariusgroup^" l»y

M.

innuitusofSt.

Lawrence

Island

; colormost nearly^likethatof M.yakutatensisbut_underpartseven

more

_stronglysuf- fusedwith brownish; feet

dusky

^{brownishinstead of}gray; skull large

and heavy

with zygomatastronglynotchedanteriorly.

Color.

—

Similarin general ^to that ofoperarius, unalascensis,

and

kadia- censis,but_slightlydarker withentireunderparts heavily

washed

with_buffy;

upperparts

cinnamon

toclay^coloruniformly

mixed

with dusky, producing a_generaleffectof

raw umber

; sides,face,

and

headessentially likeback;

underparts claycolor,sometimes_palingtograyishin pectoral

and

_inguinal regions; ^forefeet

dusky

brownish,edged with whitish gray; hind feet grayish whiteproximally,

dusky

^brownishdistally; toes

dusky

^brownish;

tailsharplybicolor,

dusky

^brownish above, whitishgray^below'.

Skull.

—

_Generalcharactersas in operarius, unalascensis,

and

yakutatensis, butsizevery

much

_larger;

zygomata more

deeply notchedanteriorly; size

*Elymocetes,from Elymus, the genericnameofthewildrye orbeachgrass often ^in- habited bythismouse anditsrelatives.

16—Proc. Biol. Soc. Wash.,Vol. XIX, ^1906. (71)

72 Osgood — _{A New}

Vole

from Montague

Island, Alaska.

about as in M. innuitus; braincase narrower; rostrum shorter; width across lacrymal processes of frontal greater; audital bullae _relatively smaller; upper^incisorslessprojectinganteriorly.

Meosurcmenls.

— _The

_type

_{and two}

topotypes, respectively^: Total length, 201 ; 191; 180; ^tailvertebrae,40; 40; 35; hindfoot (dry), 23.5; 23; ^22.

Skulloftype: ^Basallength, 31.1^; basilarlength,^29.2; postpalatilarlength, 12.1; zygomaticwidth,18.6; mastoid_width, 13.8

; length ofnasals, 9.2^; interorbital constriction, 3.9^; maxillary toothrow,^7.4.

Rnnarks.

—

_{Thisinsularform} differsfrom itsmainland relatives chiefly in decidedly larger ^{size. It} belongs ^to the so-called ^''operarius

group"

which

_{properlyincludes,} besides a

number

of Alaskan _forms,several of widedistribution inEurasia. Representatives of^thisgroup^{doubtle.ssen-} tered Alaska fromAsiaatatimenot very remote,^for although^a

number

ofAlaskan forms are

now

diflferentiated, ^all are very closely allied

and none show any marked

departure from theAsiaticforms.

The

onehere described seems asworthy^ofspecific rank as

any

^{of the others but the}

amount

ofcranialvariation inall theforms

and

the general uniformity of coloration leadsone to believethatthey might^well be rankedassub- species. If thiswere_done, however, M._oeconomus, M.kamschaticus,

and

probably M.ratticepsought^tobe includedasthey^difTerfrom

M.

_operarius

and

otherAlaskan forms onlyveryslightly.

Skulls of Microlus operarius Group.

99,373

—

M.innuitus. Type. 98,991

— _M.

_{operarius. Topotype.}

98,005

—

M.yakutatensis. Type. 107,472

—

M.unalascensis. Topotype.

137,323—^J»/. elyrnocetes. Type.