MUEID^E-SIGMODONTES— NEOTOMA FOSCIEES. 21 



would only vary as much as, say, those of South Atlantic, coast Jloridana 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 Jloridana do. The 

 gray, however, is not so slaty; being more lined with yellowish-brown, result- 

 ing in a color almost identical with that of Mus decumanus. The feet are 

 dusky, quite as in the adult. 



We should 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 fades to Mexican Muridce could be observed at ploy. 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 H. (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 

 ferruginea 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 N. 

 ferruginea ; 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 N Jloridana, it will be seen that we record three 

 specimens of that species from this locality; these are pure Jloridana, 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 fuscipes, and is an interesting parallel with 

 the case of the Hcsperomys of the same region ; for it will be seen further on, 

 that while the ordinary mouse of Fort Tejon is the "gambeli" strain of leu- 



