POCKET MICE FROM LOWER CALIFORNIA. 459 



somest species of the sfinatiis group. It has a long and 

 heavily crested tail, and differs irom peniiisiihe much as 

 P.formosus of Dulzura, Cal., differs from P.faUax of 

 the adjacent region. 



Perognathus margaritas sp. nov. 



Type from Santa Margarita Island, Lower California. 

 No. 90 ? ad. Collection of California Academy of Sci- 

 ences. Collected March 2, 1889, by Walter E. Bryant. 

 Original number, 231. 



Measurements of type (taken from dry skin). — Total 

 length, 170; tail vertebrae, 102; hind foot, 22.5; ear from 

 anterior base, 8.5. 



Average measurements of two specimens from type 

 locaHty (measured in flesh) : Total length, 182; tail ver- 

 tebras, loi ; hind foot, 22.5. 



General characters. — Similar to C. spinatits, but some- 

 what larger and darker; decidedly smaller than either 

 bryanti or peninsultB; rump spines smaller than in sfina- 

 tiis and hryantl; tail rather short and slender and only 

 sparsely crested; resembles pcninsulcs very closely in ex- 

 ternal appearance, but differs in cranial characters and 

 size. 



Color. — Upper parts varying from drab- 

 gray on sides to grizzled black and yellow- 

 ish-brown on back, from coarse admixture 

 of black hairs: under parts and feet white; 

 tail bicolor, dusky above, whitish beneath. 



Cranial characters. — Skull similar to spt- 

 iiafiis, but slightly longer, more arched and 

 relatively narrower posteriorly; interparietal 

 broadest in the middle instead of anteriorlv. 



Fig. 2. P. manmritm, "iU • • • i 



with parieto-occipital suture opposite middle, 

 instead of anterior corner (much as in calif ornicus) ; 



