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Sept., 1913 CALIl?'ORNIA I?'ORMS OF PIPILO M.4CUL.4TUS 169 The "Southern Sierran district" includes all of southern Califomla lying within the Transition Zone, and the towhee (P.m. megalonyx) ranges upwar0 into this region from the San Diegan district, unchanged. This same subspecies (as distinguished from P.m. [alcinellus) ranges well up into the southern Sierras, near the head of Kern River, but the Museum's recent (z9Iz) exploration in this region shows that most of the Sonoran species of this locality are the same as those of the coast of southern California, and it seems as though the term "San Diegan ' could well include the lower extremity of the southern Sierras east to the vicinity of Walker Pass. This seems to be the gap, rather than the Tehachapi as pre- viously supposed. The occurrence of P.m. [alcinellu.i in the Sierra Nevadan district is exactly comparable to the manner of occurrence of P.m. megalonyx in the Southern Sierran. P.m. falcifer ranges through three faunal areas, but not entirely unchanged. The increasingly humid climate from the Santa Cruz district northward is accom- panied by certain changes in the towhees of the various regions, but the variations are slight, and as gradually accomplished as are the climatic changes. P.m. curtatus is confined in summer to the Great Basin district, a small por- tion of which extends into extreme northern and eastern California. It is the only representative of this group in California which is migratory in its habits, the known winter range of the subspecies including the extremely narrow riparian strip of the Colorado River .valley, south to Fort Yuma. P.m. clementae is confined to two islands of the so-called Santa Barbara Island faunal area. This, although a convenient name by which to designate this group of islands, is unsatisfactory in that the islands form anything but a homo- geneous group, as regards their animal life. The towhees themselves are a good example of this absence of uniformity. Thus P.m. clementae, a strongly marked race, occurs on San Clemente and Santa Catalina, while on Santa Cruz the spotted towhee is practically indistinguishable from the mainland bird. In studying the differences in the various races of Pipilo maculatus in its wide distribution over the state, it will be observed that there are two distinct lined- of variation, these lines converging at the extreme southwestern corner of Cali- fornia. Starting from the southwestern form megalonyx of the San Diegan dis- trict, gradual changes can be traced to widely different extremes at the northeast and northwest, respectively. In the towhees of the coast region, from British Columbi/t to southern Cali- fornia, the back and rump of the male bird are uniformly and intensely black. The difference in color between the various coast forms lies in the extent of the white markings of wings, interscapulars and tail, and in the intensity of the chestnut coloration of sides and crissum, with oregonus at one extreme, megalonyx at tile other, and [alcifer occupying middle ground. The birds of the. interior (falcinellus and curtatus) have the rump almost invariably grayish or olivaceous; in the exceptional instances where the upper parts are almost or quite uniform, the black coloration is never as lustrous and intense as in the coast forms. Along both these diverging lines a gradual and unbroken series of inter- gradients can be followed, from oregonus to megalony.r on the one hand, and from curtatus to megalony.r on the other. In one feature, however, megalony.?- differs widely from both of the other types; for though in coloration it may be considered as intermediate between them, the exceptional development of the tarsus and foot, especially the hind claw, sets it off distinctly by itself.