MURIDA—SIGMODONTES—NEOTOMA FLORIDANA. 17 
the deserts of Arizona and New Mexico. Here the characters tally precisely 
‘ 
with those of Hesperomys “sonoriensis” or “gambeli”; indeed, they only fall 
short. of the extreme seen in Hesperomys var. eremicus. ‘The general hue, 
instead of a rat-brown mixed with blackish, is a dull pinkish fulvous or fawn, 
especially on the sides, intermixed on the back with a few black hairs. The 
heels are somewhat less hairy, and the ears a trifle larger, more ‘foliaceous” 
and nude. At the same time, curiously enough, the tail, instead of being 
extremely naked, as was to have been anticipated, is even hairier than in 
Georgia examples, and approaches the Kansas maximum in this respect. The 
young animals from the same region are paler gray than usual, corresponding 
to some samples of S/gmodon “berlandieri”; and some show a slight silvery 
margin of the ears, as usual in desert Hesperomys ‘“sonoriensis”. It is hardly 
necessary to add that this extreme, witnessed only in animals from the Colorado 
and Gila deserts, is mixed and obscured in every degree in the animals living 
in neighboring wooded and watered regions, and is directly connected with the 
Georgian extreme by Texan, Coloradan, Arkansan, and Kansan examples. 
The supposed Neotoma ‘ 
mexicana” rests upon these points of coloration; 
for, as we learn from the table given below, nothing in the way of measure- 
ments ascribed to it is distinctive. The species was originally based upon 
a few specimens, all in very poor condition, some of them indicating the 
extreme stage above described. Had Professor Baird possessed at that time 
the intermediate series we now command, it is doubtful whether he would 
have differed from Geoffroy as to their specific identity with floridana; a 
matter of which, in our mind, there is no question. 
The case of Neotoma “micropus” presents some difficulty, owing to lack 
of material; we have nothing additional to Professor Baird’s two* types. One 
of these, No. 561, is so young, that the molars are not cut at all! the skull 
measuring only 1.08, or about /a/f the normal adult average. We will, there- 
fore, confine our attention to the other specimen, No. 554. This has the 
appearance of being mature, or nearly so, except that it is, as stated, in a 
grayish-slate state of pelage. In the first place, we may dismiss the impres- 
sion that would be gained from the name ‘‘micropus”; the feet being exactly 
as long as in samples of ordinary floridana or “mexicana”, and quite as large. 
Of the many cranial characters adduced, we fail, with the skull in our hands, 
*Nos. 554, 561, published in M. N. A.—Besides these, we find in alcohol, from Santa Rosalia (Couch), 
two others, Nos. 2699, 2700, labeled “micropus”. They are, however, mere sucklings (about three inches 
long), and afford no characters at all. 
9 
4M 
