144 Merriam Little Known Kangaroo Rats. 



color ; ears darker, the anterior fold dusky except at extreme tip ; under 

 tail-stripe continuous to tip of pencil. 



Skull. Like that of montanus, but frontals narrower anteriorly, and 

 tympanic capsule smaller (shorter), with the underpart weak anteriorly. 



Measurements. Type specimen: Total length, 260; tail vertebrae, 150; 

 hind foot, 41. Average of 10 from type locality : Total length, 260; tail 

 vertebra, 147 ; hind foot, 40.2. 



Perodipus streatori simulans subsp. nov. 



Type from Dulzura, San Diego Co., California. Adult female, No. ff }f , 

 U. S. National Museum, Biological Survey Collection. November 24, 1891. 

 C. H. Marsh. Original No. 255. 



Characters. Externally so similar to streatori that I have found no con 

 stant difference except that the end of tail is not white. In spring (end 

 March) and early fall (August), and probably summer also, the color is 

 paler and more ochraceous than in late fall (October). In October speci 

 mens the dusky of the back prevails over the tawny or pale fulvous tones. 



Skull like that of streatori, but maxillary arch of zygoma less spreading 

 laterally, and cranium less squarely rectangular. In a series of skulls of 

 streatori placed side by side the maxillaries almost touch ; in a correspond 

 ing series of simulans they are separated by an interval of about 4 mm. 



Some specimens (about 1 in 10) of this subspecies appear to be inter 

 mediate between the genera Dipodomys and Perodipus, inasmuch as they 

 lack the hallux or the hallux has no claw, thus having only 4 claws instead 

 of 5. 



Remarks. This is a wide-ranging form. The Biological Survey collec 

 tion contains specimens from Dulzura and Twin Oaks (near San Marcos) 

 in San Diego County, and thence northward at least to Morro in San Luis 

 Obispo County. 



Measurements. Type specimen: Total length, 280; tail vertebrae, 165 ; 

 hind foot, 40. Average of 10 from type locality : Total length, 285 ; tail 

 vertebrae, 172 ; hind foot, 41. 



Average of 10 streatori from type locality (Carbondale, Mariposa County) : 

 Total length, 286; tail vertebrae, 175; hind foot, 42. 



Perodipus cabezonae sp. nov. - 



Type from Cabezon, Colorado Desert, California. Adult female, No. 

 54,055, II., S. National Museum, Biological Survey Collection. May 31, 

 1893. C. P. Streator. Original No. 2859. 



Characters. Size rather small (between ordi and panamintinus) ; ears 

 rather large; color buffy ochraceous. Externally most like panamintinus, 

 but ear slightly larger ; hind foot shorter ; nose paler (usual dark patch 

 obsolete) ; head and face more fulvous. 



