Dipodomys phillipsi Gray. 89 



1)o the same. In no instance was a group of holes noted, and it was rare 

 to find two entrances to the same burrow. 



"Except at Tlalpam, they were not found in considerable numbers in 

 the Valley of Mexico, and were scattered. Wherever found they were 

 always in very loose, sandy soil. At Tlalpam their burrows appeared to 

 be shared by the little yellow pocket mouse (Perognathus], which was 

 nearly as common as the Dipodom-ys. 



"As usual in this group, these animals are strictly nocturnal, and judg- 

 ing from the number of tracks, they must be very active during calm 

 nights, even when the temperature is some degrees below freezing. For 

 one or two nights during a severe storm they do not venture out, but if 

 the 'storm continues longer they forage enough to procure food- At 

 Ajusco at rare intervals a foot or two of snow covers their haunts, and 

 cold storms are common. Elsewhere in their range sharp frosts are com- 

 mon during the winter months. 



" The preceding notes concerning the habits of this species, although 

 written with particular reference to the south end of the Valley of 

 Mexico, apply equally well to other parts of its range. In the eastern 

 part of its rajige it frequents the same open sandy fields, but many of 

 the holes were also found at the bottom of shallow ditches entering the 

 ground at the foot of the low bank at the sides. Others were found sim- 

 ilarly situated along the sides of small arroyos. In one field above Chal- 

 chicomula the holes entered the ground almost perpendicularly for five 

 or six inches before sloping away at the usual slight angle. This was 

 due, however, to the fact that the very loose sandy character of the sur- 

 face soil made it impossible to start a hole in at the usual angle." 



Identity of Nelson's Specimens with Dipodomys phillipsi Gray. 



Apart from the geographic proximity of Real del Monte to the 

 region where Mr. Nelson obtained his specimens, and wholly 

 independent of the question as to whether or not the animals 

 whose burrows were observed 6 miles south of Pachuca belong 

 to the same species, or to the genus Perodipus, the specimens 

 themselves afford positive proof that they are the species de- 

 scribed by Gray as Dipodomys phillipsi, as may be seen from 

 Gray's original and very circumstantial description, which is 

 here reproduced entire : 



"A new Genus of Mexican < i Urine Mammalia. Mr. John Phillips, who 

 has lately returned from Real del Monte, Mexico, has, at the recommen- 

 dation of Mr. John Taylor, sent to the British Museum the skins of some 

 very rare and interesting birds, of a Bassaris, and of the new animal which 

 I shall now proceed to describe. This animal is very interesting, as hav- 

 ing all the external form and coloring of a Gerboa ; and it is doubtless 

 the American representative of that African genus, though differing from 

 it very essentially in being provided, like some other American genera, 



