2) “- 
turns white in winter, a phenomenon hitherto not observed in 
other Arvicoline-animals. 
For more details I refer to Coues’ above mentioned Monograph 
on this subject. 
To illustrate the details of the particular dentition and the form 
of the skull, as it was described by Coues, I have given figures 
of those parts (see the Plate, figs. 1—5), which, as far as I know, 
have hitherto not yet been figured. 
Cuniculus torquatus is distributed over the whole area of the 
Arctic Regions of America, Europe and Asia (Middendorff), al- 
though it seems to be very rare in Greenland (Brown), whereas 
according to Blackmore and Alston it is not found in Russian Lapland. - 
The latter authors !) have pointed out the distribution of this 
species in former Geological Periods. Fossil remains have been 
found as far South as England, Germany and the basin of 
the Loire. 
LEYDEN, September 1880. 
1) P.Z. S. L, 1874, p. 470. 
