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Show APPENDIX NN. 1317 is found all over the mountains, and in fall crosses the range, and is found but little less abundantly in Southern California. NOTE.- The Zonotrichia leucophrys, though not noted by us, doubtless ocenrs mingled - with flocks of the above bird, especially as it was found by us in Southern California. 19. Zonotrichia coronata ( Pall.).- Golden- crowned Sparrow. The great mass of these sparrows, in their journey southward, keeps on the western slope of the Sierras. It occurs, too, along the eastern spurs in fall, but, comparatively speaking, in very small numbers. 20. Passerella iliaca ( Merr), var. megaryncha Bd.- Thick- billed Sparrow. This appears to be the only Passerella occurring along the eastern slope, where it is numerous in summer and fall, and where I believe it is resident. In a recent report ( 1876) I was led to combine the present bird with P. schistacea, separating them from the P. townsendi and iliaca mainly on the strength of the different proportions. Subsequent examination, however, has convinced me that the genus is represented by but one species, and that the three western forms, townsendi, schistacea, and megaryncha are but varieties of one and the same species. These under different conditions of climate have become more or less differentiated from the original type till they represent well- marked geographical races, the intergradation of which with each other and with iliaca it is perfectly possible to show. As noticed in an earlier part of this report, all specimens of the variety megaryncha from the eastern slope of the Sierras show very decided intermediate characters between the extreme condition this form assumes in the Coast Range and the P. schistacea from the interior, a fact to be expected from the half- way position of the region. A series connecting the two may very readily be formed. An examination of the material in the Smithsonian, much of which was collected by the expedition, enables us to speak with equal confidence of the close relationship existing between schistacea and townsendi. Specimens connecting the two in a very complete chain may easily be selected. Hitherto no specimens intermediate between iliaca and townsendi have been met with, and though the differences separating them have been chiefly modifications of color only, differences of degree of intensity and not of pattern, this has been deemed sufficient to keep them apart. It will be remembered that the habitats of the two are, in the northwest, in close juxtaposition to each other, iliaca being one of quite a number of eastern birds that in the north find their way across the continent and reach Alaska. Townsendi, with its summer home in the northern portion of the Paoifio province, also reaches Alaska, and it is probable that here the two forms come together. At all events, a series of sixteen specimens collected by the expedition in California, in 1875, presents unquestionable evidence of the intergradation of the two. Of these I do not find one which compares exactly with the usual style of townsendi, as it appears in specimens from Kodiak, Sitka, eto. The oue extreme of this series exhibits quite a close approach to the dark olive- brown of townsendi, with its unstreaked dorsum; the other in its light condition quite suggests the ferruginous style of coloration of iliaca; such specimens have the baok obsoletely streaked. One other specimen from California in the Institution so closely approaches iliaca that it was so labeled, and supposed in the absence of others showing its true relation to be a straggler of this species. In connection with the above suite its position as one of the series showing the intergradation of the two forms is readily seen. The following measurements illustrate the relations, in size, the four forms bear to each other: P. iliaca: Wing, 3.40; tail, 3.07; bill, .32; tarsus, .93; ( average of ten specimens.) P. townsendi: Wing, 3.20; tail, 3.15; bill, .49; tarsus, .94; ( average of twenty- three specimens.) P. schietacea: Wing, 3.13; tail, 3.37; bill, .44; tarsus, .91; ( average of nine specimens.) P. megaryncha: Wing, 3.21; tail, 3.58; bill, .51; tarsus, .93; ( average of eight specimens.) As will be seen from the above measurements, schistacea and megaryncha agree in having the tail considerably in excess of the wing; while in iliaoa and townsendi the wing exceeds the tail. In townsendi, however, this discrepancy in favor of the wing is very slight, and, indeed, in some few specimens the two are equal, or the tail may even be slightly in excess of the wing. It would appear, therefore, that in respect to the relative size of these parts, townsendi indicates the first step in the variation, which is seen to be more marked in schistacea, and to find the limit in megaryncha. One unexpected fact shown by these measurements is, that not only does an increase in length or tail take place in the three western varieties, a variation shown in other species, whose habitat extends from the eastern into the western province, but a decrease in size of wing. The different proportions which ensue come, then, from two |
