The pattern of the pigment in the medulla of the hair, however, does vary specifically. Comparable samples from _Z. trinotatus_, _Z. princeps_, and _Z. hudsonius_ of the same age, sex, and season reveal a pattern characteristic for each species (see figs. 35-37). All species of _Zapus_ agree closely in color pattern. A broad longitudinal dorsal band of some shade of yellow-brown flecked with black hairs is bordered by a lateral band of a lighter color usually containing fewer black hairs than on the dorsum. The underparts are usually white but are sometimes suffused with color resembling that on the sides. Between the white underparts and the darker color of the sides there is often a narrow, clear ochraceous stripe. Dorsal and lateral hairs are uniformly grayish-white at their bases; only the distal parts of the hairs are responsible for the external color of the animal. The pelage of juveniles is usually finer and softer than the pelage of adults. The lateral and dorsal bands are not so conspicuously marked in young animals, and individual hairs are not so long or so wide as in adult animals. [Illustration: FIGS. 35-37. Photomicrographs of underhairs (middle third) from each of the species of the genus _Zapus_. × 500. FIG. 35. _Zapus t. orarius_, adult, female, No. 20293 MVZ, 3 mi. W Inverness, 300 ft., Marin County, California. FIG. 36. _Zapus p. oregonus_, adult, male, No. 47856 KU, Harrison Pass R. S., Ruby Mt's, Elko County, Nevada. FIG. 37. _Zapus h. pallidus_, adult, male, No. 22954 KU, 4 mi. N, 1-3/4 mi. E Lawrence, Douglas County, Kansas.] Preble (1899:7) and Howell (1920:226) remark as to the noticeable difference between pelages of spring and early fall. The pelage in spring is described as bright and fresh whereas that in fall is dull and worn. Actually both bright and worn pelages can occur in any one population at any one time. Some newly molted individuals are in fresh unworn pelage; some individuals, which are molting, are in ragged, worn pelage; and other individuals perhaps could be found to represent intermediate stages.