Compared with the skull of the male of nevadensis that of munda averages larger in every part measured and specimens from Point Arena are nearly as heavy again, have relatively more expanded zygomata and mastoid processes but are relatively narrower anteriorly as shown by the breadth of the rostrum, interorbital breadth and postorbital breadth. Also the braincase is less inflated anteriorly, the tympanic bullae are lower and the skull is more angular. Females show the same differences although in different degree. Compared with the skull of the male of M. f. nigriauris, that of munda from Point Arena averages larger in every part measured except for the length of the upper tooth-rows. Relative to the basilar length, the skull of munda averages broader across the mastoids and across the zygomata, is deeper through the braincase at the anterior end of the basioccipital, and has a greater development of the lambdoidal crest.
Remarks.—The skin and part skull, no. 536/1849, U. S. Nat. Mus., taken by Lieutenant W. P. Trowbridge at San Pablo Bay, is the first specimen known to have been saved of this subspecies. Since 1899 when O. Bangs diagnosed munda as of small size, the weasel of the humid costal belt north of San Francisco Bay has been regarded as smaller than bridled weasels from farther south in the State. Actually, however, the weasel of the humid costal belt shares with M. f. pulchra the distinction of being one of the two largest weasels in California.
M. f. munda may be a composite subspecies, for the variation in facial markings, in coloration otherwise, in external measurements and in size and shape of skull is great. At one time in the course of the present study, manuscript accounts of two subspecies were prepared for the animals now all called munda and there is still much justification for recognizing two subspecies, one, along the coast proper, the larger, darker-colored animal with reduced white facial markings and large, wide, heavily ridged skull from Point Arena, and 6 miles south of Laytonville, Mendocino County, along with the specimens from 5 and 6 miles west of Inverness, Marin County, and the other, an inland race, which is a smaller, lighter-colored animal with more extensive white facial markings and a smaller, narrower, skull, known by specimens from Point Reyes [station?], Nicasio, 15 mi. north of San Rafael, Freestone, Vallejo, and Mount Sanhedrin. The differences between these two lots of specimens are of great degree. However, a female from Fort Bragg proves to be no larger than three females labeled as from Point Reyes. Also, a male from 2 miles south and one mile east of Stewarts Point on the coast has a skull no larger than the animal from Vallejo, whereas the skin alone of an adult female from 3 miles south of Stewarts Point is large and agrees with the specimens from Point Arena. Consequently, no logical ranges can be worked out for the two variants with the material now available.
Finally, the type specimen of munda is a "runt," smaller than any other male seen. This specimen, purchased by E. A. and O. Bangs from C. A. Allen, who collected and sold specimens widely, was labeled as from Point Reyes. So far as this place-name is concerned, it might refer to: (1) The point of land by that name which projects out into the Pacific Ocean, (2) an abandoned ranch house bearing that name at the head of Drakes Bay, 6 miles north and 3-3/4 miles east of the actual point, or (3) the railway station by the same name at the head of Tomales Bay, 12 miles east and 4-3/4 miles north of the actual point. Allen, himself, lived near San Geronimo (then Nicasio) about nine miles southeast of the Point Reyes railway station. All these places are in Marin County, but differ markedly as regards climate and flora. The first two are treeless, windswept and have much fog, whereas Point Reyes Station is more often sunny, and is situated in a shallow valley, inland, where the open grass-covered west-facing slopes meet the east-facing wooded ones. From which one of these three places the type specimen came, I do not know. The same may be said of the three female specimens labeled Point Reyes; two of these are in the United States National Museum and one in the Field Museum.
The specimens in the Museum of Vertebrate Zoölogy from 5 and 6 miles west of Inverness and those from near the same place in the collection of John Cushing come from within a couple of miles or less of the Point Reyes represented by the abandoned ranch house. These specimens, as remarked above, agree with those from Point Arena in large size, reduced facial markings and wide skull. These are points of difference from the smaller variant suspected of being a recognizable subspecies. It is the smaller variant which the type specimen approaches in size, and with which it agrees in relatively well-developed white facial markings. This suggests that the type specimen came from Point Reyes Station rather than from either of the two other places bearing the name "Point Reyes," from one of which, as just stated, the variant of large size is known. The three females labeled "Point Reyes" also have well-developed white facial markings and are of lesser size than the female of similar age from Point Arena, Mendocino County. The presumption is that these three females also came from Point Reyes Station.
The smaller, inland variant seems to agree in size, cranial characters, and coloration with M. f. nigriauris to the southward of San Francisco Bay, but lacks the black on the head which characterizes nigriauris. The larger variant, on which the description here used for munda is based, comprises animals which differ from nigriauris in larger size, darker color, reduced white facial markings, and larger, relatively wider skull. Both of the variants mentioned above are sharply distinct from nigriauris on the basis of coloration of the inside of the ear which is blackish in nigriauris like the dark facial markings, and in munda is colored like the back. M. f. munda lacks the dark facial markings; an occasional specimen has at most, a trace of the markings but this does not extend back so far as the ears. This difference, blackish versus non-blackish face, persists eastward of San Francisco Bay to at least as far as the Carquinez Straits, where a specimen of munda is available from 4 miles north of Vallejo and one of nigriauris from Glen Frazer Station on the south shore opposite Vallejo.
Fig. 30. Map showing the geographic distribution of subspecies of Mustela frenata in California