Range.—Northwestern coastal region of California, from Russian Gulch State Park, Mendocino County north to Trinidad, Humboldt County. Zonal range: humid Transition.
Description.—Size medium; color dull; back near Ochraceous-Buff with heavy admixture of black hairs, forming broad dorsal band; sides from near Ochraceous-Buff to near Ochraceous-Salmon, sometimes with heavy admixture of black hairs; lateral line usually distinct, sometimes blending with color of belly and side; ventral surface usually suffused with color of sides; tail bicolored, dark brown above, white to yellowish-white below; feet grayish-white above; ears dark, edged with color of sides; auditory bullae large; pterygoid fossae broad; incisive foramina relatively short; palatal bridge short; maxillary tooth-rows relatively short; narrow across zygomata; braincase narrow; interorbital region narrow; zygomatic arch relatively short.
Comparisons.—From Zapus trinotatus trinotatus, Z. t. eureka differs in: Size smaller; ventral surface with much greater suffusion of ochraceous; auditory bullae larger; pterygoid fossae relatively broader; frontal region less inflated; palatal bridge shorter; braincase narrower; narrow across zygomata; upper tooth-rows shorter.
For comparison with Zapus trinotatus orarius see account of that subspecies.
Remarks.—Howell (1920:230), without having examined the material, provisionally referred specimens from Requa and Crescent City, Del Norte County, California, to Z. t. eureka. I have studied this material and find the specimens to be intermediate between Z. t. trinotatus and Z. t. eureka in cranial characters (zygomatic breadth, interorbital width, and breadth of braincase), but nearer Z. t. trinotatus in coloration (absence of ochraceous suffusion ventrally). They are here referred to Z. t. trinotatus. The zone of intergradation between Z. t. trinotatus and Z. t. eureka seems to extend from Requa, California, north to Gold Beach, Oregon, where other specimens intermediate between these two subspecies, have been obtained. These individuals are also referred to Z. t. trinotatus on the basis of cranial features and color.
Specimens examined.—Total, 42, all from California, distributed as follows: Humboldt Co.: Trinidad, 4 (SDM); Carsons Camp, Mad River, 3 (USBS); 3 mi. W Arcata, 5 (MVZ); 73/10 mi. E Bayside, 1 (MVZ); 12 mi. S Korbel, on Maple Creek, 2 (MVZ); Falk, 1 (MVZ); Carlotta, 1 (MVZ); F. B. Summer Redwoods, S Eureka, 1 (MVZ); Maple Creek, 1 mi. W junction Mad River, 12 (MVZ). Mendocino County: Mendocino City, 1 (MVZ); Albion River, 1/3 mi. E MacDonalds Ranch, 1 (MVZ); Russian Gulch State Park, 10 (MVZ).
Marginal records.—California: Trinidad; Russian Gulch State Park; Albion River, 1/3 mi. E MacDonalds Ranch; Mendocino City; Carlotta.
Zapus trinotatus montanus Merriam
Zapus trinotatus montanus Merriam, Proc. Biol. Soc. Washington, 11:104, April 26, 1897; Bailey, N. Amer. Fauna, 55:234, August 29, 1936.
Zapus montanus, Preble, N. Amer. Fauna, 15:28, August 8, 1899.