MAMMALS. 197 
Among the terrestrial species, I am not sensible 
of any important movements taking place requiring 
especial notice. The species of Mus, or some of 
them, are liable at times through want to shift their 
quarters, but this actis veryrare. In the reported 
migration of the noctule bat to and from Italy, I 
place no confidence. The advance of man in the 
work of cultivation of the soil and other operations 
connected with his civilized condition, has restrict- 
ed the number of several offensive and destructive 
kinds, such as the otter, the weasels, the fox, &c. 
and has done much towards the greatly-to-be-de- 
plored extermination of others, particularly the 
badger, and red deer. The same circumstances 
however, are congenial to the unnatural increase of 
some sorts, such as the rat, and mouse, and perhaps 
the squirrel, and nearly all the species of land 
mammals are influenced in greater or less degree, 
by human operations in respect of their numbers 
and distribution. The extent of the catalogue is 
probably due to the varied kinds of aspect present- 
ed by the country, and the general mildness of the 
climate ; it probably exceeds that of any other dis- 
trict of the same size in England. The migrations 
of our cetacea have not yet been sufficiently deter- 
mined to admit of any observations. About 13 
species of this tribe have been recognised by Couch 
as occurring in Cornwall. Delphinus deductor has 
recently been captured in Ireland, a herd having 
appeared on the coast. 
