16 



MOXOGRAPna OF XORTII AMERICAN RODENTIA. 



n scanty pilosily, especially outside; they are very large and nearly orbicular, 

 with moderate antitnigiis. On tlie tail, the long body-hairs run out a little 

 ways beyond what seems to Iji" its true root, and occasion some discrepancy 

 of measurement with diHereiit persons. This mend)cr is rarely, if ever, 

 ([uite 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 ^onWana 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 oi Jloridana, 

 the tail is sharply and perfectly bicolor — slaty-gray above, pure white below ; 

 and, in general, the upper surface of th&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 

 lias alrca<ly been given; in this species, the posterior one, that sliows in 

 iiakcd-lieeled species like ferruginea, is not apparent. These tubercles, and 

 generally most of the sole, are blackish ; the toes, and the whole palms, 

 flesh-colored. 



The cliangcs of pelage, with age, are precisely as in Hesperomys leucopm, 

 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 i)rownish on the sides. This color insensibly gives way to the normal 

 hues of the adults; there arc 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 iV: fuscipcs. 



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 soutiiern-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 els.^where, 

 all tlic prairie Murines and Arvicolines, if not, indeed, all the prairie mammals, 

 siiow the .sime thing. The pallor reaches its maximum in the specimens from 



