PROCEEDINGS

Vol. XXI, ^pp. 141-142 June 9, 1908

PROCEEDINGS

OFTHE

BIOLOGICAL SOCIETY OF WASHINGTON

A NEW WHITE-FOOTED MOUSE FROM ALASKA.

BY WILFRED

H.

OSGOOD.

In orderto provide^a

name

for

immediate

^{use in}another con- nection, thefollowing ^brief description ^ispublished ^{ofa white-} footed

mouse

representing ^the

form

_prevalent

on most

of the islandsof southeastern Alaska.

Although

^{material is}

now

avail- able

from

_nearlyall these _islands, afew_pointsstill

remain

to be cleared

up

regarding peculiarities of geographic distribution.

Certain

well-marked forms

_apparentlyareconfined to particular islands while others, ^like the present ^one,

show

little or

no

dif- ferentiation

from

island toisland.

Very

^littlevariation in color appears

among

the several

forms

ofthe region

and

distinctions rest

mainly on

^dimensions

and

cranial characters. In order not to anticipate unpublished ^{results of a} study ^of the large

group

to

which

this

form

_belongs, it is given ^full specific rank with onlylimited discussion of relationships.

Peromyscus

hylaeus sp. nov.

Type from Hollis, Kasaan _Bay, Prince ofWales Island, Alaska. No.

127,038, U. S. National Museum, Biological SurveyCollection.

May

15, 1903.

W.

H. _Osgood.

Geographicdistribution.

—

Islandsandcoastofsoutheastern Alaska west andnorthwestoftherange ^ofP. macrorhinusincluding Prince^ofWales, Kupreanof, Mitkof,and _Admiraltyislands and the mainlandcoastfrom

Lynn

^{Canalto FrederickSound.}

Characters.

—

Most similar toP. keeni of the Queen ^CharlotteIslands, butskullmorelightly builtwith therostrum _longerandmoreslender

; size

decidedly^less than in macrorhinus and_sitkensis; color darker and ears and tailshorterthanin oreas.

Color.

—

Practically ^{as in} keeni, macrorhinus, and other _{species of} the humid Pacific coast; sides varying from ^{russet to}Mars brown_shadingto

Mars brown andProut

Brown

ontheback; underparts white^{; tail}sharply bicolor.

19—Proc. Biol.Soc.Wash., Vol. XXI,^1908. (141)

142 Osgood

— _{A New}

_White-Footed

_{Mouse From}

_Alaska.

Skull.

—

_Mostsimilartothatof oreas,butnasalsand rostrum averaging slightly more _slender; similar to that of keeni, but more _lightly built throughout; rostrum andnasals longerandmore_slender; posterior nasal endingsusually exceeding premaxillse; infraorbitalregionlighter; some- whatsimilartothatofmacrorhinus, butdecidedly smaller.

Measurements.

—

_Average of 20 adult topotypes: Total _length, His.4 (191-205); ^tail vertebrae,98 (91-105); hind _foot, 23 (22-23.5); earfrom notch (dry), 15.3.(14.5-16.8). Skullsof type ^aiid one _{topotype, respec-} tively: Greatest length, 26.9; 27; basilar length, 21; 21; zygomatic width, 13.2; 14; interorbital constriction, 3.8; 3.9; interparietal, 9.6x 3.2; 9.4 x _{3; nasals, 10.5; 10.9;} shelf of bony palate, 4; 4.2; pala- tineslits, 5.9; 6; diastema, 7.5; 7.4; postpalatal length, 0.1; 8.8; max-

illarytoothrow, 3.7; ^3.0.