4 NATURAL SCIENCE [July 



Mr Gerrit S. Miller, jun., who, in the Proceedings of the Biological 

 Society of Washington (xi., pp. 77-87, April 21, 1897), considers 

 that there are six valid species. These fall naturally into three 

 groups, each of which occupies a different geographic region. They 

 generally inhabit dry, grassy plains and mountain parks, and, 

 except for some small characters in the teeth, are much like the 

 ordinary Microtus ; from the humid coast district of Oregon, how- 

 ever, there comes a long-tailed form, which appears to be strictly 

 arboreal. 



The Geographical Distribution of the Dragon-flies 



One of the greatest surprises in store for the student at the 

 outset of his study of zoo-geography is the discovery that animals 

 so different in their powers of locomotion as mammalia and birds 

 agree nevertheless so closely in geographical distribution, that 

 a map representing the zoological areas of the one class, will, in its 

 broad outlines, be equally applicable to the other. The obvious 

 inference to be drawn from this circumstance, the inference, namely, 

 that the actual means of progression, whether it be flight or swim- 

 ming or running, are far less important factors in determining the 

 dispersal of species than one would be led on a 'priori grounds to 

 suppose, is still further supported by a recent paper on " The 

 Geographical Distribution of Dragon-flies," published by Mr G. H. 

 Carpenter in vol. viii. of the Scientific Proceedings of the Royal Dublin 

 Society. Though this paper is chiefly nothing but a compilation 

 from Mr W. F. Kirby's catalogue of the Odonata, it is nevertheless 

 a valuable piece of work, since it represents in a concise and 

 intelligible form the range of all the genera of the great order of 

 powerful-flying insects, and is accompanied by a map showing how 

 closely in the main their distribution tallies with that of the other 

 orders and classes of terrestrial animals that have been faunistically 

 studied. Seven regions are recognised : the Holarctic, comprising 

 the Palaearctic of Sclater and Wallace, phis the Nearctic almost down 

 to the fortieth parallel of latitude ; the Ethiopian ; the Mascarene ; 

 the Oriental ; the Australian, including New Zealand ; the Sonoran ;. 

 and the Neotropical. It is interesting to note that there is no 

 evidence of a Mediterranean region in the Old World corresponding 

 to the Sonoran of the New, and that the species from Madagascar 

 are no more Ethiopian than Oriental in their affinities. The advo- 

 cates of Lemuria may get some satisfaction from the latter circum- 

 stance; but those who are in favour of an Antarctic area will not 

 gain much support from the dragon-flies, since the species of these 

 insects that inhabit Patagonia, Cape Colony, and New Zealand bear 

 no witness to a former land connection between these countries. 



