1920] Howell: A Study of the California Jumping Mice 231 



Zapus orarius Preble 



Point Reyes Jumping Mouse 



Zapus orarius Preble (1899, pp. 29-30). 

 Type.— Male adult; no. 2,50; coll. E. A. and O. Bangs; Point Eeyes, Marin 

 County, California; May 14, 1893; collected by C. A. Allen; original no. 618 {fide 

 Preble, 1899, p. 29). 



Range.— Bunch grass marshes on the uplands of the Point Reyes 

 Peninsula, Marin County, California. Number of specimens exam- 

 ined, 17 (2 in coll. A. B. Howell), all from the type locality. 



Diagnosis.— An ochraceous-bellied species with rather short, dully 

 bicolor tail. Distinct from, but perhaps nearest to, Z. t. eureka; 

 coloration brighter, foot and tail shorter. Skull shorter and more 

 slender, the supraoccipital region lighter, rostrum shorter, lighter, and 

 narrower at all points. The interorbital width is less, incisive fora- 

 mina shorter and comparatively wider. The interpterygoid fossa is 

 narrower and the anteorbital foramina and bullae slightly smaller. 



External characters.— In this species, the tail averages less than 

 58 per cent of the total length, while in all other California forms, this 

 member is 60 per cent. Only May and June skins are available, and 

 in these, the dorsal areas are rather poorly defined, the black hairs 

 outnumbering the lighter ones but slightly if at all. The head is 

 uniform with the back and the general color tone is bright ochraceous 

 buff. In most of the skins, the hairs of the underparts are uniformly 

 tipped with the color of the sides, but a few specimens are somewhat 

 lighter in this region. 



Skull— Orarius has the smallest skull with narrowest interorbital 

 width, shortest incisive foramina and shortest molar series of any 

 form in the state. It and eureka have especially tapering rostra and 



large bullae. 



Measurements.-Ayersige, in the flesh, of 11 apparently adult topo- 



types : length, 224.3 mm. ; tail, 129.4 ; foot, 31.6. 



Remarks.— Z. orarius is a well defined species and apparently 

 intergrades with no other form. However, it is not impossible that 

 specimens which are intermediate between it and eureka may be found 

 along the coast of Sonoma County. Its closest relationship is certainly 

 with the latter form. From alleni, it is separated by a wide stretch 

 of Upper Sonoran territory. 



When Preble (1899, pp. 29-30) named the species, he had but two 

 specimens from the type locality, and with these he listed an individual 



