,308 Field Columbian Museum — Zoology, Vol. III. 



Osgood, but olivaceous and black. According to Mr. Osgood's 

 Monograph, they ought to be magruderensis , but great emphasis 

 is placed by him upon the size of that race, and all these examples 

 are considerably smaller than the measurements given, the largest 

 Vicing, total length, 1S1; tail vertebra', 95; hind foot, 23, as 

 compared with 108, 107, 26; and an average of the six before 

 me would be much less than the dimensions of the selected 

 specimens given above. In color they agree with Dr. Merriam's 

 description fairly well. According to Mr. Heller, this form was 

 common in sage-brush areas on the summit of the Invo Moun- 

 tains at S,5oo feet. 



Perognathus formosus. 



Perognathus formosus Merr., X. Am. Faun., 1889, p. 17. Elliot, 

 Syn. N. Am. Mamm., 1901, p. 250. 



71 Specimens: 8 Old Woman's Springs, 2 Victor, 12 Oro 

 Grande, n Daggett, 2 Copper City, 7 Lone Willow Spring, 11 

 Wild Rose Spring, 4 Hannopee Canon, 2 Ballarat, 12 Furnace 

 Creek. 



I refer all of this series to the present species, as thev are 

 all large individuals, with the hind foot measuring as high as 

 27 millimeters, the average, however, being probably about 25. 

 The examples from Lone Willow Spring are the largest, averaging 

 about 200 mm. in total length. The two specimens from Bal- 

 larat are of a reddish color different from all the others. Whether 

 this is an individual variation, or characteristic of this localitv. 

 cannot be decided, as no more examples were taken at that 

 place. Mr. Osgood considered some of his examples from the 

 Panamints to be magruderensis, but in this series I am unable 

 to distinguish more than one form. There is a variation in 

 size, but this must be expected among individuals where so 

 much depends upon the tail to determine the total length. The 

 hind foot, however, varies but slightlv in dimensions among 

 them all. Mr. Heller writes of this species that "throughout 

 the Mohave Desert this is the most abundant and widespread 

 species of pocket-mouse. In the Death Valley region it occurs 

 from the floor of the valley to a height of 7.500 feet on the 

 Panamint Mountains, which carries it to the lower edge of the 

 Pinon Belt. Rocky hillsides and canon walls are the usual 

 haunts of the species." 



