MURIDAI—SIGMODONTES—NEOTOMA FUSCIPES. 21 
would only vary as much as, say, those of South Atlantic coast floridana do. 
We have no very young animals before us; but Nos. 1159 and 1182 show 
much the same signs of juvenility that the same ages of floridana do. The 
gray, however, is not so slaty; being more lined with yellowish-brown, result- 
ing ina color almost identical with that of Mus decumanus. The feet are 
dusky, quite as in the adult. 
We sbould very much like to see specimens of this species from other 
localities, especially a little to the southward, where the physical influences 
that give the peculiar facies to Mexican Muride could he observed at play. As 
De Saussure has remarked (/. c.), there is a tendency to extension of the color 
of the back down the legs and on to the feet in the Mexican forms of Hespe- 
romys ; thus, in H. aztecus, the basal third of the metatarsus is sharply dusky, 
while, in 4. (Nyctemys) sumichrasti, the whole metatarsus to the toes is 
dusky. These two species also finely illustrate two other parallel tendencies : 
these are, to the change of the ochrey or yellowish-browns of northern species 
into a rich rusty red, with lengthening and blackening of the tail. Neotoma 
Jerruginea of Guatemala and Southern Mexico shows likewise all three of 
these features. Neotoma fuscipes, with closest relationships, if any, to Mexi- 
can forms, shows us the beginning of changes that appear to culminate in NV. 
Jerruginea ; but we have no links to excite suspicion that it is not perfectly 
distinct from the last named, as it certainly is from any other United States 
species. 
Mr. Samuels’s Petaluma examples are strictly identical with Cooper's 
types. 
The Fort Tejon example is interesting, and merits special mention. By 
referring to our table of WV. floridana, it will be seen that we record three 
specimens of that species from this locality; these are pure floridana, abso- 
lutely identical with South Atlantic styles; they do not even approach in color 
the paler “mexicana” of the neighboring desert regions. But No. 3655 is 
equally pure fuscipes; the dusky occupies the posterior two-thirds of the 
metatarsus, and the tail, which is only an inch shorter than the head and body, 
is of a nearly uniform blackish color all around. This occurrence, at Fort 
Tejon, of the two species of Neotoma, each preserving its own characteristics, 
confirms the specific distinctness of /uscipes, and is an interesting parallel with 
the case of the Hesperomys of the same region; for it will be seen further on, 
that while the ordinary mouse of Fort Tejon is the “gambeli” strain of deu- 
