922 



MONOGKAPnS OF NOBTO AMBBICAN IIODBNTIA, 



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tlinn Mic liiick. Tlioro is ^ciirnilly iilso a prominent wliitisii-yellow patch in 

 front of lli(! siioultlcrs on tlic sides of the neck, where the hairs arc also very 

 coarse and stiff. 



In young specimens, tlic under fur is sometimes clear grayish-white, and 

 the white tips of the overlying hairs are also longer than in the adults, with 

 the sul>terniinal zone darker. The rump, the sides of the neck, and a sjiot 

 at the base of tlie ears are conspicuously pale yellowish-white. In several 

 very young specimens (apparently but a few weeks old) from Colorado, the 

 whole top of the head is intense black, and there is an abundanccof soft under 

 fur on the ventral surface. 



Arctomy8 Jlaviventcr difTcrs, as already noted, from A. monax in its difler- 

 ent coloration, larger size, smaller ears, and relatively much longer tail. It« 

 nmch longer and much more heavily clothed tail affords at once a readily 

 available distinctive characteristic. The coloration is also much more golden 

 than in A, monax. The differences afforded by the skull have also already 

 been detailed under that species. 



From A. pruinosus, it differs in its much smaller size, as well as in its 

 totally different coloration, and in important cranial differences. A more 

 detailed comparison will be given under A. pruinosus. 



Arctomys Jlaviventer was first described in 1841 by Audubon and Bach- 

 man, from a specimen in the collection of the Zoological Society of London, 

 brought by Douglass "from the mountains between Texas and California". 



The habitat of this species extends from Western Texas, New Mexico, 

 and Arizona northward throughout the Rocky Mountains to probably beyond 

 tiie forty-ninth parallel. It occurs also in the Black. Ililla of Dakota, and 

 specimens are in the collection from California. It is apparently a strictly 

 alpine species. It is very abundant in the mount«iins of Colorado, occurring 

 chiefly in the neighborhood of timber-line, and ranges to a considerable dis- 

 Uincc above the forest vegetation, where it makes its home among the rocks. 

 It is to some extent gregarious, like the A. marmota of Europe. 



