Proceedings of the Academy of Natural Sciences of Philadelphia (Volume 39)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1910 Excerpt: ...of an inch in diameter, with the funnel expanding, within a length of half an inch, to an inch or more in diameter. The following were ordered to be published: THE OCCURRENCE OF BUFO COLUMBIENSIS EAST OF THE ROCKY MOUNTAINS. BY ROBERT T. YOUNG. High mountain chains, especially those whose crests extend above timber line, are more or less efficient barriers to the spread of animals. This is more particularly so in the case of species which do not migrate easily from place to place. The capture of Bufo columbiensis on the eastern slope of the Continental Divide in Colorado is, therefore, of some interest. In August, 1902, I obtained a specimen of this toad on the eastern slopes of the Arapahoe Peaks, about 28 km. west of Boulder, Colo., at an altitude of about 3,100 m., and it has since been reported to me by Prof. Beardsley, of the Colorado State Normal School, from the eastern slope of the mountains west of Greeley. Cope1 gives this species as a characteristic of the Pacific district of the Western sub-region of the Medicolumbian region, included in the Transition of Merriam.2 My records, however, show it to occur in the Hudsonian zone, far above the upper limit of the Transition, where it has doubtless migrated from its original habitat. There are several passes in northern Colorado over the Continental Divide which cross the mountains below timber line, affording possible paths of migration for toads from the western to the eastern slope. Further observations on the distribution of this species on both slopes of the mountains, taken from year to year, would doubtless be of interest as affording some data for a determination of the conditions and rate of migration of toads. 1 The Geographical Distribution of Batrachia and Reptilia in North America, Am. Nat...