THE ORKNEY GRASS MOUSE 465 
Nests of dry grass and roots, having a greatest diameter of 
from 5 to 8 inches, are placed in rounded chambers in the 
They are never at the end of a run, 
centres of small mounds. 
but are approached by a network of paths suggestive of a mole’s 
“fortress.” 
The mice may be seen in their runs all day, but that does 
They 
not imply that they are not also active in the night." 
swim well, and Mr Millais states that if pursued they will plunge 
into a pool rather than go round by land ; one which he released 
in a pond dived under the surface. 


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Fic. 74.—PLAN OF NESTS OF ORKNEY VOLE. 
the base of the mound.) 
They do not seem to be very prolific nor to have a long 
sexual season, and for this reason, perhaps, no “plagues” are 
known to have occurred in the Orkneys. Mr Millais reports 
that the first litters appear in April, and he has seen half-grown 
But Mr Kinnear found no 
young at the end of September. 
young at the end of May, except one about a quarter grown, 
1 Ogilvie-Grant caught one at 10.30 P.M. 
