304 MURIDZ—LEMMUS 
of the prehistoric fauna, having been identified also from 
Forest of Dean, Gloucestershire; Ightham, Kent; Langwith, 
Derbyshire; and Dog Holes, Warton Crag, Lancashire. It 
was probably present at Hoe Grange Quarry, Longcliffe, 
Derbyshire, as well as (with Dzcrostonyx) in the earlier brick- 
earth of Erith, in the Thames Valley (see Newton, Geol. Mag., 
October 1890, 455).’ 
In Ireland it is known only from Doneraile Cave, Co. Cork, 
where it was discovered by Ussher in 1904 (/ourn. Cork Fizst. 
and Arch. Soc., xvii., 92, 123; Irish Naturalist, 1904, 237 and 
248, also 1910, 42), along with mammoth, bear, reindeer, wolf, 
and a large hare (true Lepus). 
Some of its remains have such a fresh appearance that the 
animal may well have survived until prehistoric or historic 
times. Those from Portugal included the entire dried skins 
and ligaments of two complete individuals. 
Hinton concludes that the lemmings, helped by their well- 
known migratory habits, reached Ireland, with the ancestor of 
the Irish Hare, during the latter part of the pleistocene period, 
at which time the land stood high enough to lay bare the bed 
of the North Sea to a latitude somewhere north of the Dogger 
Bank. The meagre Irish fauna shows that the connection 
between Ireland and England could only have been inconsider- 
able or temporary, probably between Carnarvonshire and 
Wicklow. 
The absence of Z. Zemmus from Siberia, from the south- 
west and south of Sweden, and from the late glacial deposits of 
Denmark (Winge, Vdensk. Meddel. Naturh. For., Kjobenhavn, 
1904, 3, 223) caused Stejneger to suggest (Swzths. Mise. 
Coll, 4th May 1907, 478), with much probability that, 
with the Varying Hare of Norway, it reached Skandinavia 
from Scotland by means of a land bridge across the 
North Sea. 
No ancestral forms of Zemmus occur in Britain, whither it 
probably came from the East. Its absence from eastern North 
America and Greenland seems to indicate an Old World origin, 
1 Hinton (Proc. Geol. Ass., 3rd June 1910, 496) believes that remains from Uphill 
Cave, Weston-super-Mare, Somersetshire, represent a second species as yet un- 
described. 
