The Hair of California Mammals with Keys to the Dorsal Guard Hairs of California Mammals

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Abstract
Hairs of 392 spp. and ssp. of California mammals, exclusive of the orders Primates and Cetacea, were examined to determine comparative structure. Samples were taken from the mid-dor sum and mid-venter, half-way between the tip of the nose and the base of the tail. They were cleaned in carbon tetrachloride, dried, and mounted in balsam for viewing general form and pattern of the shaft, cortical and medullary relationships, and pigmentation. Patterns of the cuticular scales were imprinted on the transparent plastic "EthoceH" and examined as a positive image. Keys have been constructed which make possible the identification of the orders, families, and genera, and the majority of spp. of California mammals on the basis of hair alone. The keys are based on the guard hairs of the dorsum, which possess the greatest number of differentiating characteristics. 5 major criteria for hair identification are established. In order of importance they are: (1) general form and size-length, width, degree and point of tapering, spatulate tip, strictures, and other gross morphological characteristics; (2) type of medulla-presence or absence, simple or compound, diameter, ratio of width to width of shaft, and pattern; (3) cortex-extent, ratio of width to medullary width, and presence or absence of fusi; (4) pigmentation-distr., color, and form of pigment; (5) cuticular scales (least valuable of the criteria due to subjectivity in interpretation). Implications of hair structure for systematics are indicated. More detailed diagnoses of the families and orders of California mammals are also given.

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