ART. XX.-THE COLEOPTERA OF THE ALPINE REGIONS OF THE ROCKY MOUNTAINS. BY JOHN L. LECONTE, M. D. The elevated interior region of North America presents peculiarly favorable opportunities for the study of some of the most interesting questions connected with geographical distribution of animals and plants. If the materials at our hands be, as indeed they yet are, a very scanty representation of the organic forms now living in that part of the continent, they are, at least, sufficient to indicate the direction in which investigations should be pushed, in order to arrive at definite and final results. The peculiarly favorable circumstances to which I chiefly refer at present are dependent on the following points in the development of the region: 1st. The gradual enlargement of the land-surface at the expense of the circumambient seas during the latest Mesozoic periods. 2d. The gradual elevation of the middle of the continental mass during post-Cretaceous times, so as to greatly modify the climate in respect to both moisture and temperature. These changes have been so gradual, that we may say with certainty (excluding the local eruptive phænomena, which were more numerous, but not remarkably different from those of the present age) there has been no great or paroxysmal disturbance destructive of the land-surface in the elevated plains east of the Rocky Mountains since the deposition of our early Cretaceous strata (Dakota Group). 3d. While, during the Glacial epoch, the valleys of the mountains were filled with glaciers of moderate size, and the line of permanent ice streams and fields brought to a much lower level, there was an absence of the extensive ice sheets and flooded areas, which in Eastern America destroyed entirely the terrestrial organized beings of the former period. It must be inferred from the first and second of these premisses, that the new land exposed by this gradual development of the continent received its colonies of animals and plants from the conterminous older land-surfaces in various directions, and that the subsequent elevation of the continental mass, by which the moisture was diminished, caused a later invasion of the territory by those genera and species which are characteristic of arid regions. We may also conclude, from the third premiss, that the glacial displace ment of species in the Rocky Mountains has been much less than in Eastern America, and that a very small area would be left bare of life on the return to a normal temperature; consequently, the previous occupants of the higher mountains would again return to their former domain, increased by refugees from the circumpolar continent of temperate climate, driven southward by the increasing cold. Such being the case, it ought to be possible, with well-prepared lists of the insects of the Plains and mountain regions, by comparison with lists of the local fauna of other zoological districts of the continent, to ascertain, with reasonable probability, the invasions from different directions by which, in the first place, the newly emerged land was colonized; and, in the second place, the modifications, either in distribution or in structure, which have subsequently occurred. I have on another occasion* expressed my belief that the study of the distribution of existing insects could give much information concerning former topographical and geographical changes in the surface of the earth. I then gave several examples to show how the distribution of species peculiar in their habits and structure confirmed what was already known by geological investigation of the gradual evolution of the middle part of the continent. I will now advance the additional thesis, that we may obtain somewhat definite information of the sequence, extent, and effects of geological changes in the more recent periods by a careful study of the insect fauna in its totality. While these pages were being prepared, I received from Mr. T. Vernon Wollaston † a copy of his excellent volume on the small Coleopterous fauna of Saint Helena. This fauna, containing but 203 species, is remarkable for the large predominance of Rhynchophora, of the families Cossonida and Anthribide. It has, however, been greatly contaminated by the introduction, through commerce, cf foreign species to the number of 74, or nearly three-eighths of the number now known to inhabit the island. The introduction of these 74 exotic species, in addition to the other changes produced by human agency, must have greatly modified the pre-existing fauna, by repressing some and extinguishing others of the aboriginal species. In the case of a portion of a continental area, such as is under consideration for my present purpose, the problems are by no means so simple. The human agency in the introduction of foreign species is slight. The * Trans. Am. Assoc. Adv. Science, 1875, Detroit, President's Address. + Since writing the above paragraph, I have been informed of the death of this most estimable and laborious investigator. The last of his publications was the memoir on the Coleoptera of Saint Helena, referred to in the text. The monographs of the Coleopterous faunæ of the Atlantic Islands by Mr. Wollaston are among the most complete and exhaustive contributions to fa unal Entomology published. Their full importance can only be appreciated when more thorough investigations of the Beetles of the American and African Atlantic slopes are made and careful comparisons instituted. It will then be found that several genera of the Atlantides which do not occur on the other continent are represented in the American fauna. geological and meteorological changes are all-powerful in increasing or diminishing the districts of distribution, and in determining the directions from which additions to the fauna may have been made. I have purposely avoided mentioning in the discussion among these categories the modification in situ of pre-existing forms, because this is an influence which is easily invoked and but rarely manifested. Its effects, therefore, if capable of being demonstrated, can be appreciated better only after the elimination of the coarser and more tangible machinery of topography and climate in producing migrations. DESCRIPTIONS OF NEW SPECIES. I avail myself of the present opportunity to describe several species from Colorado, which have the appearance of being mountain species, though their localities are not definitely known to me. For the purpose of making this memoir more useful to those who will pursue the investigation, I have availed myself of the kindness of Mr. O. Reinecke, of Buffalo, who has submitted to me a very good set of species collected last summer at Atlanta, Idaho, by Mr. L. Allgewahr. Several new forms were contained in this series, and a complete list of all the species. collected is added as an appendix. The elevation of Atlanta is estimated at about 7,800 feet. The Nebric mentioned in the list of Alpine species are fully described in the short essay on the North American species of that genus, added as a second appendix. CARABIDÆ. 1. PTEROSTICHUS (CRYOBIUS) SURGENS, n. sp. Shining black, with bronze-brown lustre; antennæ dark brown; palpi and legs red-brown. Prothorax wider than long, rounded on the sides for two-thirds the length, narrowed behind, and sinuate towards the base; basal angles rectangular; anterior transverse impression well defined, dorsal line distinct, basal impressions double, the inner one long and deep, the outer one short and fine; base not margined. Elytra not wider than prothorax, elongate-oval, humeri not rounded; striæ fine, interspaces flat, 3d with two dorsal punctures situated on the 2d stria behind the middle. Length 8.5mm (0.34 inch). Alma (10,000 feet), Argentine Pass (13,000 feet), Colorado. Closely allied to P. fatuus from Alaska, but the prothorax is not so broad, and the sides are much less rounded and less sinuate towards the base. 2. PLATYNUS JEJUNUS, n. sp. Elongate and very slender, piceous, not shining. Head narrow, eyes small, not prominent. Antennæ half as long as the body, 3d joint a little longer than the 4th. Prothorax elongate-oval, narrower behind, sides very slightly sinuate near the base, reflexed margin narrow, not wider behind, basal angles rectangular, but not prominent, and slightly rounded at tip; disc flat, dorsal line fine, basal impressions small. Elytra elongate-oval, flat, finely striate, narrowly margined, obliquely sinuate towards the tips, which are divergent and separately rounded (?), or nearly acute (8). Length 10.5-13.3mm (0.42-0.52 inch). Mountains of California, Oregon, Nevada, and Idaho. Very similar to P. dissectus, but the surface is not shining; the side-margin of the prothorax is not wider towards the base, and the basal angles are less elevated. The elytra are less strongly margined, and more finely striate. The species of Platynus which constitute the subgenus Rhadine may be separated as follows: The form is very slender; front tarsi without grooves; middle and hind tarsi with lateral grooves. Hind angles of prothorax well defined. Elytra elongate-oval, flat, strongly margined, obliquely sinuate towards the tips, which are divergent. Color brown or blackish; antennæ and legs paler. Third joint of antennæ much longer than the fourth. 2. Apical angles of elytra less acute Apical angles very long, divergent... 3. Shining.. Subopake 3. AMARA (CURTONOTUS) CYLINDRICA, n. sp. 2. 3. ...larvalis. caudatus. ... dissectus. •jejunus. One from South Park, Colorado, (8,000 to 10,000 feet), agrees with a specimen from Slave Lake, and is very near to others from Lake Win. nipeg. It is allied to A. lacustris Lec., but the elytra are more convex and narrower, and the color is darker, with a distinct metallic gloss. The sides of the prothorax are rounded almost to the base, the sinuosity is very short, but the hind angles are equally prominent. The metathoracic side pieces are marked with a stria each side, and scarcely punctured. The 1st and 2d ventral segments are feebly punctured, and there are a few scattered punctures at the side of the metasternum. The legs are dark brown; the upper tooth of the inner side of the middle tibiæ is acute and prominent, the lower one is very small. Length 10mm (0.40 inch). 4. HARPALUS CLANDESTINUS, n. sp. Elongate, oblong-oval, piceous-brown, antennæ, palpi, and legs rufotestaceous. Prothorax wider than long, sides rounded in front, then nearly straight, but very feebly sinuate to the hind angles, which are rectangular, not at all rounded; base emarginate, side-margin more reflexed than usual, explanate and sparsely punctulate towards the base; basal impressions narrow, slightly punctured. Elytra not wider than prothorax, striæ deep, impunctured, interspaces slightly convex; dorsal puncture upon 3d stria; outline oblique towards the tip, but not sin |