288 REVIEW— THE NATURAL HISTORY OF SOUTH DEVON. 
Devon, greater difference in its fauna from that of a spot not 
so affected may be anticipated. We refer our readers to the 
work itself for the list of the animals of South Devon, with their 
habitats. Of mammals, we have 43 — -five of the species belong 
peculiarly to Devon. Of birds, we have 247 — three, or probably 
Jour, of which have as yet been noticed only in this district. Of 
fishes, forming a part of Devon’s fauna, there are 110 ; the 
total of those limited to Devon and Cornwall, conjointly, are 41. 
Of land and fresh-water shells we have about 56 — four species of 
the division of the molluscs seem to be limited to this district, 
while of the marine molluscous animals, usually termed shell- 
fish, we have about 250 ; and the total of these species peculiar 
to South Devon shores, or, in some few cases, common to the 
shore's of Devon and Cornwall, 55. Of the radiata, we have 
about 120. 
It will thus be seen that the county of Devon yields to none 
in the importance of its fauna ; and this is chiefly owing to its 
peculiar physical condition, in possessing a combination of scenic 
beauties ; for in the mountainous, the sober, the tranquil, the bold, 
and the marvellous does Devon outvie Scotland, and even the 
more interesting and delightful of the midland English counties. 
Alluding to the geographical distribution of animals in ge- 
neral, and particularly on the zoological geography of South 
Devon, the author is particularly happy. He considers that 
there are two sets of laws in operation on the geography of ani- 
mals , — primary and secondary . The primary law, on which the 
distribution of animals depends, having a pretty general influ- 
ence, and which seems, indeed, altogether in unison with the 
aggregate of our zoological knowledge, is “ the gradual failure 
in numbers of individuals of a given species, as we recede from 
the point which, from their comparative plenty there, we pre- 
sume to be their principal seat. Together with the numerical 
failure, we see likewise, as might easily be conceived, a failure 
or deterioration in size, in qualities, in colour, and in all other 
endowments;” and to so great an extent is this occasionally 
carried, that naturalists are frequently at variance in their deci- 
sions on the species, some considering such specimens as dete- 
riorations, others naming them as separate species, or, at least, 
as formal varieties. It is seen that, independently of distance 
from the seat of luxurious growth and great numerical increase, 
specimens having all the appearance of such as are found at 
the very verge of the geographical range of a species are con- 
stantly detected within short distances. The author considers 
these primary causes as quite unknown to us, and likely to con- 
tinue so, though it would appear that the various parts of the 
