598 Description of Meadow Mouse. 
at Dresden, found them to consist of fine rock-powder, in which he 
identified fragments of quartz as the most prominent constituent, 
besides feldspar, plagioclase, green hornblende in considerable 
quantity, mica (mostly biotite), a trifling amount of magnetite, 
numerous dendritic or, sometimes, kidney-shaped grains of an ochre- 
like mineral, and fine particles of clay and limestone. Such a com- 
position (says he) indicates certainly that this loess leads its origin 
substantially from disintegrated primitive rocks (gneiss or granite) 
and diorite. ` 
The dust on the inland ice of Greenland offers a suitable soil for 
quite a number of small algæ. Professor V. B. Wittrock examined 
some of the samples of kryokonite, and the results of his investi- 
gations are embodied in his paper, “Om snöns och isens flora.” * 
(To be concluded.) 
DESCRIPTION OF A NEW PRAIRIE MEADOW 
MOUSE (ARVICOLA AUSTERUS MINOR) 
FROM DAKOTA AND MINNESOTA. 
BY DR. C. HART MERRIAM, 
LARGE series of meadow mice of the genus Arvicola, col- 
lected during the past two years in Minnesota and eastern 
Dakota, comprises but two species, which, in the field notes of the 
collector, Mr. Vernon Bailey, are designated respectively as “ up- 
land” and “lowland” meadow mice. The “upland” form is neve? 
found on the marshes, but the “lowland,” which is most abundant 
in wet meadow lands and in the neighborhood of streams, some- 
times occurs on the dry prairies in company with the other. Exter- 
nally, some of these mice resemble one another so closely that sharp 
discrimination is necessary for their separation. A glance at their 
teeth, however, shows that they belong to different sub-genera 
The “lowland” species has two external closed triangles on its last 
upper molar, a postero-internal loop or “spur” on its middle upper 
1 A. E. Nordenskiöld : Studier och forskningar, föranledda af minas 
resor i höga norden. Stockholm, 1883, pages 63-124. 
