16 MONOGRAPHS OF NORTH AMERICAN RODENTIA. 
a scanty pilosity, especially outside; they are very large and nearly orbicular, 
with moderate antitragus. On the tail, the long body-hairs run out a little 
ways beyond what seems to be its true root, and oecasion some discrepancy 
of measurement with different persons. This member is rarely, if ever, 
quite so decidedly naked and scaly-annular as in Mus, though often closely 
approaching this condition. ‘The most naked and scaly and least bicolor tails 
are generally shown by the original floridana from the South Atlantic States ; 
while western specimens, even those from deserts, as the Camp Grant ones 
below tabulated, have more hairy tails, and the hairiness reaches a maximum 
in some Kansas examples. Here, not far from the habitat of the bushy-tailed 
species, we find tails, of which the hairs are a fourth or even a third of an 
inch long, completely concealing the annuli, forming a slight terminal pencil, 
and, in fact, not distinguishable at first glance from some of the scantiest- 
haired (early-spring) specimens of cinerea. In these examples of floridana, 
the tail is sharply and perfectly bicolor—slaty-gray above, pure white below ; 
and, in general, the upper surface of the tail tends to a gray, darker than the 
back. The soles are closely pilous as far as the posterior tubercle, and a slight 
fringe continues all along their sides. The disposition of the tubercles 
has already been given; in this species, the posterior one, that shows in 
naked-heeled species like ferrwginea, is not apparent. These tubercles, and 
generally most of the sole, are blackish; the toes, and the whole palms, 
flesh-colored. 
The changes of pelage, with age, are precisely as in Hesperomys leucopus, 
and most other species of that genus. The young animal is slaty-gray above 
and slaty-white below, almost black along the middle of the back, a little 
more brownish on the sides. This color insensibly gives way to the normal 
hues of the adults; there are no definite intermediate stages. - In the very 
youngest animals, the hands and feet are snowy-white, as on the old; a fact 
particularly to be noted in connection with the study of WV. fuscipes. 
In specimens from the same locality, there is not very much individual 
variation in color, it would seem, aside from the conditions of immaturity. 
As a rule, the southern-coast specimens are the darkest and most rat-colored, 
with most indistinctly bicolor tails, lacking the brighter ftlvous hue that marks 
those from the dryer regions of Kansas and Arkansas. As noted elsewhere, 
all the prairie Murines and Arvicolines, if not, indeed, all the prairie mammals, 
show the same thing. The pallor reaches its maximum in the specimens from 
