HETEROMYID.i; 167 



in the hope of getting more. They are easily recognized by 

 the ears and tail being white with but very little dusky mark- 

 ings. 



Perognathus formosus Merriam. (Comely.) 



LONG-TAILED POCKET-MOUSE. 



Size large; tail much longer than head and body; ears large; 

 the antitragus prominently lobed; above grizzled sepia; below 

 white; tail buff mixed with dusky above, buff belowi; cranium^ but 

 slightly arched; mastoids well developed; interparietal large and 

 wide; interorbital space wide. 



Length about 190 mm. (7.50 inches) ; tail vertebrae 106 

 (4.15); hind foot 24 (.95). 



Type locality, St. George, Utah. 



Southwestern Utah, west to Owen Lake, California. 



Perognathus longimembris Coues. (Long membered.) 



SAN JOAQUIN POCKET-MOUSE. 



Above buff mixed with more or less black ; below white ; lat- 

 eral line indistinct; tail buff, darker above, lighter below; skull 

 large; mastoids of moderate size; interorbital region narrow. 

 Young; darker and more olivaceous. 



Length of male about 145 mm. ( 5.70 inches) ; tail vertebrae 

 74 (2.90); hind foot 19 (.75). Female smaller. 



Type locality, old Fort Tejon, Kern County, California. 



Southern part of the San Joaquin Valley. 



Subgenus Chaetodipus. 



Mastoids relatively small and not projecting beyond the 

 plane of the occiput; pelage of adult harsh, often with spines or 

 bristles on the rump. 



