1G MONOGRAPHS OF NORTH AMERICAN ItODENTIA. 



a scanty pilosity, especially outside; they arc 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 occasion some discrepancy 

 of measurement with different persons. This member is rarely, it' 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 jloridana 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 jloridana, 

 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 fetruginea, 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 N. 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 fulvous 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 



