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 lke 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 @& 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, plus 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. 
