ENTOMOLOGY OF COLORADO. 313 



that of Packard (8d Rep. U. S. Ent. Coiuni.) and most other zoolo- 

 gists. In this new arrangement the old central region is abolished, 

 and a new region, the Sonoran, is made to stretch from the Atlantic 

 to the Pacific. 



I have been interested in examining the fticts presented in the 

 present paper, and others known to me, to see how far they supported 

 these changes. So far as I am able to judge, the suppression of the 

 central region is entirely justified, but I cannot agree as to the pro- 

 posed Sonoran region. An analysis of the insects of the Colorado 

 Rocky Mountains shows that the high-alpine and mid-alpine ele- 

 ments, although sufficiently distinct, are both essentially boreal. If 

 we follow Dr. Merriam's arrangement, it appears that the high- 

 alpine is truly boreal, while the mid-alpine belongs to the transition 

 region, containing a considerable number of strictly American types. 

 The sub-alpine, on the other hand, is southern or Sonoran. 



Dr. Horn has kindly given me his opinion, as follows: 



"My ideas of the distribution of Coleoptera in the mountainous region of 

 Colorado, which is a good centre of the Kocky Mountain chain are as follows: 



"The high region seems to have been populated from the Canadian through 

 the H. B. T. region. A collection made above 8000 feet in Colorado is almost 

 identical with one made in the Lake Superior region. The same fauna runs 

 down to N. M. and Arizona, and again appears, mixed, of course, in the Mexican 

 Mountains. 



"The sub-alpine region is one that continues from Washington to New Mexico, 

 as shown by such striking forms as Ergates, Melanophila miranda, IpJdhimus 

 serratns. Gnleruca externa, Calosoma lunatnm in varieties. 



"The lower region, foothills, etc., is a mixture of New Mexico forms with 

 those of the eastern United States, with some peculiar forms allied more to the 

 southern regions. 



"California is a peculiar region, and, in many respects, allied to Europe (in 

 general). I think California supplies us with more species of genera peculiar to 

 Europe than does the Eastern region." (In litt., July 14, 1892.) 



According to the facts now recorded it seems that there is, firstly, 

 a circunipolar and strictly boreal element; secondly, a boreal but 

 modified or Canadian element ; and thirdly, a southern element be- 

 longing to the arid portion of Dr. Merriam's Sonoran region. I do 

 not think any distinct faunae except these can be recognized, and the 

 central region accordingly falls. But there is, sprinkled among the 

 ordinary types, a distinct element of endemic species, to which I shall 

 refer later. There also seem to be a few surviving fragments of an 

 ancient fauna, of which Anthrucopteryx is a good example. 



There seems to be a; small Californian element, but the species 



TRANS. AM. ENT. SOC. XX. (40) NOVEMBER, 1893. 



