ENTOMOLOGY OF COLORADO. 305 THE ENTOMOLOGY OF THE ]»IID-AI.PINE ZONE OF CTISTER COUNTY, COLORADO. BY T. D. A. COCKERELL. The present paper is based upon collections made during a resi-dence of about three years (1887-1890) in the district to which it relates. Although the number of insects already recorded from Colorado is very great, the information available, from which a stu-dent of geographical distribution can arrive at satisfactory conclu-sions, is comparatively scanty. The reason of this unfortunate state of affairs is, that the great majority of recorded species are cited, merely as from Colorado, without the locality or altitude being given ;' and as within the limits of the State there are two or three distinct faunae, the result on compiling the statistics is something like a jum-ble of the faunjB of Alaska, Minnesota and Texas. Owing to this meeting of different faunpe in Colorado, the State as a whole is ex-traordinarily rich in species. The insect fauna of the mid-alpine zone of Custer County presents some elements which are sufficiently diverse ; but taken as a whole, it is a natural fauna, belonging to a well-defined region, and hence available for comparison with other like faunae. It is, indeed, truly characteristic of the mid-alpine, that besides its ordinary elements, it contains species coming up from the sub-alpine, and down from the high alpine; but although it thus ha-ppens that Junonia ecenia and Parnmsius milnthem have been taken in the same zone, it does not follow that either are truly characteristic of it, or that they be-long to the same fauna. All faunal lists contain such exceptions or deviations from the average ; but when, as in the case of Colorado as a whole, there is no uniformity about the range of the various species, and the majority do not occur throughout the territory, it is impossible to treat the region as containing a single fauna. The insects herein enumerated are only a portion of those taken, but they are enough to draw conclusions from. Almost the whole of my collections have been distributed, and very many of the more obscure species are at the British Museum unidentified. The Cole-optera are mainly in Dr. J. Hamilton's collection, and I have been TKANS. AM. ENT. SOC. XX. ' (39) NOVEMBER, 1893.