GEOLOGICAL SURVEY OF THE TERRITOEIES. 383 



geograpliical position of the region, the species were a mixture of 

 those from Oregon and those from the plains, the great mass being 

 those more common in the latter region. A few years since a collection 

 was made by Mr. Gabb, of the California geological survey, from Fort 

 Hamath, Oregon, to Boise City, Idaho, completing with the present 

 series a line from the Pacific to the plains. We are thus enabled to 

 trace the distribution of various species and their varieties. As is well 

 known to all collectors, various species of Meodes occur in great num- 

 bers in all parts of the west of our continent, and the species themselves 

 occur over a wide range of territory, and are not limited, as might be 

 inferred from their apterous condition, to regions of small extent. As 

 we pass from east to west over a given line, we find variations of aver- 

 age temperature, and of course great differences in altitude. These two 

 causes, combined with, of course, the botanical changes, have tended 

 to produce variations from a given type to a greater or less extent. 

 Uleodes ohscura, Say, affords a beautiful illustration of the extent to 

 which this divergence may be carried. As a general rule I find, not 

 only in Meodes. but also in many other genera, that the higher the ele- 

 vation or the colder the climate the rougher and more deeply sculptured 

 is the species. The smoother forms of U. ohscura may therefore be ex- 

 pected in the southern regions in which it occurs j for example, var. 

 dispersa is New Mexican, elytra with scarcely any traces of striae; var. 

 ohscura, elytra distinctly sulcate, but not deeply, is from Colorado and 

 Southern Idaho. As we advance to the west the elytra are more deeply 

 sulcate, as in var. arata, while var. sulcipennis, from nearer the Pacific 

 coast, has deeply sulcate elytra, with very convex interspaces. The same 

 variation of sculpture occurs in Calosoma luxatum, Say, which starts in 

 Colorado with comparatively smooth elytra, until in Vancouver we find 

 the elytra covered with lines of granular elevations, forming the variety 

 known as Cpimelioides, Walker. The two extremes of each series above 

 noted appear to differ widely from each otlier, and to be entitled* to 

 rank as distinct species. In the foregoing remarks reference only has 

 been made to variations within specific limits. The same law appears 

 to hold between different species. In the genus Omus the most roughly 

 sculptured species occurs in Washington Territory, (0. Dejeanii, Keiehe,) 

 and the smoothest ( 0. Iwvis, Horn) from near Yisaiia, California. The 

 object of the preceding remarks is to explain what appears to be a law 

 of variation for our western slope, and thus cause the unnecessary mul- 

 tiplication of species, founded on slight characters, to be avoided. 



Species everywhere in our fauna appear to be distributed on lines of 

 country presenting as nearly as possible similar meteorologic conditions. 

 Thus many Oregon forms extend southward into California, gradually 

 seeking a higher mountain habitat as the region becomes warmer. Two 

 species illustrate this — Tragosoma Harrisii and PhryganophUns collar is. 

 Both extend their habitat from Maine to Calilbrnia,, following the cooler 

 regions westward from Maine through the Canadas and Eed Kiver 

 region, thence northward nearly to Sitka. From the latter point south- 

 ward to Oregon both occur at ordinary level, and rising as a more 

 southern region is reached until at the latitude of Visalia they occur 

 only a short distance below the snow-line, at an altitude of from ten to 

 twelve thousand feet. 



From Southern California species have extended along the desert 

 regions bordering the Colorado Piver to Utah. Two instances are pre- 

 sented in the collection just examined — Calosoma^ scniikcve and Aniso- 

 dactyl us piccus. Species advancing from the region just cited cannot be 

 expected to cross the Pocky Mountains. Our couunon llar2)alus caligi- 



