RODENTIA —MURINAE—HESPEROMYS MYOIDES., 473 
will not be proper to place the species in this genus. Unaccompanied by any other features of 
external form or internal structure, the presence or absence of a cavity in the mouth can 
scarcely be looked on as other than specific characteristics merely. 
The description and figures by Dr. Gapper, in the Zoological Journal, agree very well with 
the specimens before me. He speaks of the species as abundant in the district of Upper Canada 
between York and Lake Simcoe. The tail of his specimen measures 3} inches; the body, 
(probably stretched,) 33. ; 
For an excellent specimen of this species the Institution is indebted to the Montreal Natural 
History Society. 
In another specimen, 2776, from Waterville, New York, referable probably to the same 
species, I found the cheeks crammed with large seeds, and on cutting them open could see that 
the latter occupied a pouch of considerable size. It is possible, indeed, that this specimen 
(immature) may not belong to the H. myoides ; if so, we must conclude that in the ability to 
distend the cheeks very much, even temporarily, the H. leucopus approaches very closely to the 
H, myoides, and this diminishes still more the propriety of placing the latter in a distinct 
genus. It is quite possible that others of our species may have cheek pouches more or less 
developed. ; 
The Hesperomys gracilis of Major Leconte, from Ohio, agrees very well in length of tail with 
this species, and otherwise resembles one of the Burlington specimens. It is, however, in the 
dried specimen, impossible to ascertain whether cheek pouches were ever present or not. The 
tail vertebree measure 3.60 inches, 3.70 with the hairs; the body (stretched) is about 3.70. 
The hind feet, .85. In the length of tail, so much greater than what is usual in H. leucopus, 
I have little hesitation in referring it to the H. myoides. The specimen came from Michigan 
or northern Ohio. 
List of specimens. 
Measurements. 
Nature of 
specimen. 
Locality. Whence and how 
obtained. 
Original number. 
Catalogue number. 
| Sex and age. 
| Nose to eye. 
| Nose to ear. 
Nose to tail, 
Tail to end of hairs. | 
| Length of fore foot. | 
| Length of hind foot. 
| Height of ear. 
: | Oorresp’g No. of skull. 
2 | Tail to end of vert. | 
ys a 
. ose to occip. 
9 p 
.| La Prairie, near Montreal, | Montreal N. H. Society} 46 | Mounted..| .60 |...... 4.20 | 3.76 | 4.16 |..... | 85 67 
Canada. 
833%) ....0+/+...| Burlington, Vt. .......06+ | Prof. Z. Thompson .... 
713123 
13133 
Q741 |... 
2742 |... 
2743 
Q744 |... 
2745. 
2746 |... 
2776 
+ Measured after being mounted. 
* Original of Thompson’s description of Mus leucopus. 
® Measured before skinning. 
60 L 
