162 Proceedings of the Biological Society of Washington. 



eremicvs it differs in having greater inter-orbital width, larger bullae, and 

 shorter, heavier rostrum. 



Measurements. — Type: Total length, 307; tail, 129.5; hind foot, 35.5. 

 Averages of series (type, no. 318 9 coll. A. B. H., nos. 6D c? and DX19 c? 

 coll. D. R. Dickey) : Total length, 261.5; tail, 110; hind foot, 34. 



Remarks. — Comparing the ages of the skulls with their sizes, I judge that 

 cienegae is a larger animal than confmis. Although sign was common at two 

 small spots near the type locality, the animals were very shy, and continued 

 trapping by L. M. Huey and myself during the greater part of the winter, 

 resulted in the capture of but five individuals, three of which were obtained 

 accidentally. 



