288 
U. S. P. R. R. EXP. AND SURVEYS-ZOOLOGY—GENERAL REPORT. 
Measurements of skulls. 
Current 
number. 
Locality. 
Length. 
Width. 
172 
Carlisle, Pa......_.... 
1. 41 
173 
1. 30 
.88 
949 
Racine...................__ 
1. 33 
.76 
List of specimens. 
Catalogue number. 
Corresponding number 
of skull. 
Locality. 
When 
collected. 
Whence obtained. 
Nature of 
specimen. 
Measurements. 
From tip of nose to— 
Tail to end 
of— 
Length of— 
Eye. 
Ear. 
Occip 
Tail.' 
Vert. 
Hairs. 
Fore ft. 
Hind ft. 
536 
Montreal, Can. 
! Thomas Broome. 
Skin .. , t .. 
5.60 
1.20 
2508 
Middleboro’, Mass. 
Spring, 1856.. 
J. W. P. Jenks....... 
In alcohol.. 
60 
1.18 
1.50 
4.70 
3.40 
4.90 
.87 
2509 
.do. 
.do. 
. ...do. 
.60 
1.18 
1.50 
4.70 
3.70 
4.40 
.80 
1.14 
2510 
Essex county, N. Y. 
Dr. S. E. Hale. 
....do. 
.50 
1.00 
1.35 
3.40 
2.60 
3.00 
.70 
1.09 
860 
New York city.. 
Geo. N. Lawrence ... 
Skin. 
5.00 
2.90 
4.10 
1.14 
Washington, D. C. 
Dr. Nichols. 
In alcohol.. 
2504 
Columbus, Oa 8 .. 
Dr. W. Gesner. 
....do. 
.60 
1.20 
1.50 
4.76 
3.60 
4.20 
.73 
1 19 
2505 
.do. 
..do. 
....do . 
.55 
1.14 
1.46 
4.55 
3.50 
4.18 
.70 
1.10 
2506 
West Northfield, Til. 
R. Kennicott.... .... 
.... do ..... 
.60 
1.20 
1.50 
4.76 
3.60 
4.30 
.73 
1.23 
827 
“Racine, Wis.......... „ TT 
Dr. P. R. Hoy. 
Skin ,,,, r 
5.00 
1.20 
.do. 
4.20 
3.40 
4.10 
1.05 
786 
Columbus, Miss ,. 
Dr. W. Spillman. 
In alcohol 
5.00 
3.60 
4.10 
1.10 
787 
4.80 
3.40 
3.90 
3.02 
1259 
342 
Prairi« Mer Rouge, La.... 
Jas. Fairie.. 
Mounted 
2652 
Skin - T ... 
5.20 
3.20 
4.00 
1.08 
PTEEOMYS HUDSONIUS. 
Northern Flying Squirrel. 
Sciurus hudsonius, Gmelin, Syst. Nat. I, 1788, 153. 
Pleromys hudsonius, Fischer, Synopsis, 3825, 365. 
Sciurus sabrinus, Shaw, Gen. Zool. Mamm, I, 1801, 157. 
Ptermys sabrinus, Rich. Zool. Jour. Ill, April, 1828, 519.—Ib. Fauna Bor. Amer. I, 1829, 193. 
Wagner, Suppl. Schveber, III, 1843, 228. 
Aud. & Bach. N. Am. Quad. Ill, 1853, 202 ; plate cxliii, fig. 1. 
Secern river flying squirrel, Pennant, Hist. Quad. II, 1781, 418.— Ib. Arctic Zool. I, 1784, 122. 
Sp. Ch.—C onsiderably larger than the P. volucdla, or common flying squirrel. Tail considerably shorter than the head 
and body; (shorter than the body alone f) Above, yellowish brown; beneath, white; the hair plumbeous at root. 
Length of head and body about eight inches; of tail, with hairs, 5J. Hind foot, 1. 60 inches. 
I regret that the only materials at my command for the description of this species consist of 
some very imperfect skins. In these the only differences from Pteromys volucdla I can realize 
are the considerably larger size, and the under hairs of the belly, instead of being white at the 
roots, are lead colored. The tail is proportionally shorter. In almost every respect, however, 
the one is a miniature of the other. The upper part of the tail is colored like the hack, some¬ 
times with a mixture of darker towards the tip. 
