$Unique_ID{QAD00253}
$Pretitle{}
$Title{Rocky Mountain Flying-Squirrel     (Northern Flying Squirrel)}
$Subject{Rocky Mountain Flying-Squirrel     (Northern Flying Squirrel); Pteromys; Alpinus}
$Journal{Quadrupeds of North America:  Volume III}
$Volume{Vol. 3:206-208}
$Genus{Pteromys}
$Species{Alpinus}
$Common_Name{Rocky Mountain Flying-Squirrel}
$Log{
Plate CXLIII--Left.*00252P1.scf,35470016.aud
Audio*35470016.aud
Genus*00024.txt}

               (C) (P) Library of Natural Sounds 1990-91, 1992,
                              All rights reserved.
       Portions copyright (c) Creative Multimedia Corp., 1990-91, 1992

                       A U D U B O N ' S   M A M M A L S

                    By John James Audubon, F. R. S., &c. &c.

                                      AND

                     The Rev. John Bachman, D. D., &c. &c.

                  -------------------------------------------
                                   VOL.  III.
                        --------------------------------


                       PTEROMYS ALPINUS.--AUD. and BACH.
                              [Glaucomys sabrinus]

                        ROCKY MOUNTAIN FLYING-SQUIRREL.
                           [Northern Flying Squirrel]

                             PLATE CXLIII.--FIG. 2.


     P. Magnitudine P. sabrino major, cauda plana, lata, corpore longiore,
patagio lumbari angusto, margine recta.


                                  CHARACTERS.

     Larger than Pteromys sabrinus; tail, flat and broad, longer than the body;
flying membrane, short and with a straight border.


                                   SYNONYME.

     PTEROMYS SABRINUS (VAR. ALPINUS).  Rich., F. B. A., p. 195, pl. 18.


                                  DESCRIPTION.

     Head longer and body stouter than in P. sabrinus; the tail is also longer,
much broader, more densely clothed with hair, and has a flatter and more
elliptical form; the flying membrane is much smaller than in P. sabrinus, and
the border is straight; the ears are thin and membranous, have a little fur at
the base on the upper surface, and are thinly covered on both sides with short
adpressed hairs; their form is semi-oval with rounded tips; the tail is flat,
oblong, and oval in form; the extremities are rather stout, more especially the
hind-feet; the soles, palms, and under surfaces of the toes are well covered
with fur, except a small callous eminence at the end of each toe.  There are
five eminences on the palm, of which the two posterior ones are the largest; and
four on the soles, situated at the root of the toes.  There is a brush of soft
fur near the outer edges of the soles; the fur is dense, very long, and has a
woolly appearance; the longest hair on the back is fully an inch in length.


                                    COLOUR.

     Head, nose, and cheeks, light grayish, with a slight wash of yellow;
surface of the fur on the back, yellowish-brown, without any tendency to the
more red hue of the back in P. sabrinus.
     The fur of the throat and belly is a grayish-white, without any tinge of
buff colour; tail, blackish-brown above, a little paler beneath.


                                  DIMENSIONS.

                                                              Inches.

     From point of nose to root of tail,  .  .  .  .  .  .  .  8 1/2
     Tail (vertebrae),  .  .  .  .  .  .  .  .  .  .  .  .  .  5
     Tail (including fur), .  .  .  .  .  .  .  .  .  .  .  .  6 1/8
     Heel to longest middle toe, .  .  .  .  .  .  .  .  .  .  1 1/2
     Height of ear posteriorly,  .  .  .  .  .  .  .  .  .  .    3/8
     Breadth between the outer edges of the flying membrane,.  4 3/4

     RICHARDSON states that there is a specimen in the Hudson's Bay Museum,
which measures nine inches from the point of the nose to the root of the tail.


                                    HABITS.

     We have learned little of the habits of this animal.  DRUMMOND, who
obtained it on the Rocky Mountains, states that it lives in pine forests, seldom
venturing from its retreats except during the night.
     From its heavy structure, and the shortness of the bony process that
supports the flying membrane, we are led to infer that it is less capable of
supporting itself in sailing from one tree to another, than the other species of
this genus.


                           GEOGRAPHICAL DISTRIBUTION.

     Both the specimens of DRUMMOND and TOWNSEND were obtained in crossing the
Rocky Mountains on the usual route to the Columbia river.  We have no doubt this
species will be found on the western side of the Rocky Mountains, from the
Russian settlements through Oregon to California.


                                GENERAL REMARKS.

     RICHARDSON regarded this species as a variety of Pteromys sabrinus (see our
first volume, p, 134), and adopted for it the name alpinus, not to designate a
species but a variety.  We, on the other hand, consider it a true species, and
have applied to it the name of P. alpinus, quoting RICHARDSON's var. alpinus as
a synonyme.
     On comparing the specimen from which our drawing was made, with P. sabrinus
from Quebec, the following appeared to be the points of difference:  alpinus is
considerably the larger animal, and although the legs appear somewhat shorter,
they are stouter; the fur is more dense and longer, having quite a woolly
appearance; the ears are shorter than in P. sabrinus, and are broader and more
rounded.  They may also be distinguished by the colour of their fur from each
other, that of alpinus on the under surface being pure white from the roots,
while the fur of P. sabrinus is tinged with yellowish.  The most striking
difference, however, is the extreme shortness of the bony process which supports
the flying membrane at the fore-leg.