CHAP. XVIII.] 
JAPAN AND FORMOSA, 
379 
parallel to that of the great spotted kingfisher, already referred 
to as found only in the Himalayas and Japan. 
Comparison of the Faunas of Hainan, Formosa, and Japan . — 
The island of Hainan on the extreme south of China, and only 
separated from the mainland by a strait fifteen miles wide, 
appears to have considerable similarity to Formosa, inasmuch as 
it possesses seventeen peculiar land-birds (out of 130 obtained 
by Mr. Swinhoe), two of which are close allies of Formosan 
species, while two others are identical. We also find four 
species whose nearest allies are in the Himalayas. Our know- 
ledge of this island and of the adjacent coast of China is not 
yet sufficient to enable us to form an accurate judgment of its 
relations, but it seems probable that it was separated from the 
continent at, approximately, the same epoch as Formosa and 
Japan, and that the special features of each of these islands 
is mainly due to their geographical position. Formosa, being 
more completely isolated than either of the others, possesses a 
larger proportion of peculiar species of birds, while its tropical 
situation and lofty mountain ranges has enabled it to preserve 
an unusual number of Himalayan and Malayan forms. Japan, 
almost equally isolated towards the south, and having a much 
greater variety of climate as well as a much larger area, pos- 
sesses about an equal number of mammalia with Formosa, and 
an even larger proportion of peculiar species. Its birds, how- 
ever, though more numerous are less peculiar; and this is 
probably due to the large number of species which migrate 
northwards in summer, and find it easy to enter Japan through 
the Kurile Isles or Saghalien. Japan too, is largely peopled by 
those northern types which have an unusually wide range, and 
which, being almost all migratory, are accustomed to cross over 
seas of moderate extent. The regular or occasional influx of 
these species prevents the formation of special insular races, 
such as are almost always produced when a portion of the popu- 
lation of a species remains for a considerable time completely 
isolated. We thus have explained the curious fact, that while 
the mammalia of the two islands are almost equally peculiar, 
(those of Japan being most so in the present state of our 
