984 
Journal of Agricultural Research 
Vol. XXVIII, No. 10 
when present, is located posterior to the antero-lateral one and is the most varia¬ 
ble of all. It may be entirely absent or may vary from vestigial to well developed. 
The writer’s notes show that out of 72 animals preserved 19 had six plantar 
tubercles; 24 had five; 1 but “four and a half”; while in still another individual 
there were only four distinct pads, there being but the faintest trace of a fifth. 
In addition, one animal had six pads on one foot and five on the other. This 
great variation in plantar pattern is purely individual and probably indicates 
that the sixth tubercle is in process of being lost; although it is not impossible 
that the reverse contention is the proper one. 
HIP GLANDS 
The same difficulty in a study of the hip glands is encountered as when record¬ 
ing data concerning the plantar tubercles, but to even a greater extent, for it is 
impracticable to examine the inner surface of the pelt of more than one or two 
animals at a time. This is a very real handicap, especially as the terms employed 
in describing the glands, such as faint, well developed, or reddish, are necessarily 
vague. 
Externally the glands appear as a pair of patches situated well up on the hips 
and upon which the hair is more sparse, as well as shorter, than on the remainder 
of the dorsal surface of the trunk. In the dried skins of large males they are 
about 20 mm. apart, and as they are thicker than the remainder of the pelt 
they become considerably harder and less elastic to the touch when dry. These 
glandular patches evidently consist of groups of greatly developed and specialized 
sebaceous glands upon which the hair grows with lessened luxuriance. When 
they are prominent, there is a slight exudation of liquid from them—enough 
barely to moisten them—but this is not sufficiently oily to mat the surrounding 
hair to any extent. The writer has always considered that they act as scent 
glands and, judging from their situation, that they are for the purpose of leaving 
an odorous trail upon the closely encroaching sides of the grassy runways for 
the direction of other voles. This, however, is pure speculation. The inner 
surface of the pelts of old males shows scars about the head and shoulders. There 
is also a definite zoning of scars in the vicinity of the glands, indicating that these 
are probably particular targets for the ire of rivals. Similarly, some of the 
lagomorphs invariably endeavor to bite the testes of an opponent when fighting 
among themselves. 
In a large male of the present series each hip gland measures about 30 mm. in 
an antero-posterior direction by 18 mm., and they are 20 mm. apart. Upon the 
inner side of the undistorted pelt they usually are situated wholly posterior to 
an imaginary line extending between the orifices in the hide originally occupied 
by the hind legs; but there is some variation in this respect and they may begin 
as far forward as a point half an inch anterior to such a line, thence extending 
rearward. When the glands first begin to develop there appears within the 
area a slight, whitish thickening upon the inner side of the skin, somewhat 
granular in texture. This increases in size and coarseness with age. In older 
males it becomes very thick and coarse, somewhat spongy, and at times con¬ 
gested with a conspicuous network of veins upon the inner surface. As this 
congested condition is found in some males but is absent in others, the writer 
judges that it not only indicates an increase in the activity of the gland, but that 
it may also be of a periodic nature and perhaps is dependent upon sexual ac¬ 
tivity, although this is merely an assumption upon his part. 
The glands are usually of full size in adult males and only very slightly smaller 
in subadults of medium age, although they may be of distinctly finer texture and 
are probably much less active in the latter. It is odd that the only male of con- 
