Dipodomyii phiUipsi Grajj. 89 



])v 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 Tlalt)am, they were not found in considerable nundjers in 

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

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

 be shared by the little yellow pocket mouse [Perogn'ttlius), which was 

 nearly as common as the Bipodono/s. 



'"As usual in this group, these animals are strictl}' 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, l)ut if 

 the storm continues longer thej' 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 

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

 ]\Iexico, apply equally well to other parts of its range. In the eastern 

 part of its range 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 tJie 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 inqiossible to start a hole in at the usual angle." 



Identity of Xdson''s Siyecimcns tvith Dtpodotnys jjJiiUipsi Gray. 



A])art from the geographic proximity of Real del Monte to the 

 region Avhere 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 Perodipas, the specimeijs 

 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 (Jllruie Mammalki. — IMr. John Phillips, who 

 has latelv 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 i-are and interesting birds, of a Bassaris, and of the new^ animal which 

 I shall now proceed to descril>e. This animal is very interesting, as hav- 

 ing all tiie external form and coloring of a Gerl>oa ; and it is doubtless 

 the American representative of that African genus, though difl'eriug from 

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



