The geographical distribution of animals, with a study of the relations ...

;chap, iv.] ZOOLOGICAL EEGIONS. 71are, for our present purpose, of much less importance. As aprimary division the " Arctic region " would be out of all proportionto the other six, whether as regards its few peculiartypes or the limited number of forms and species actually inhabitingit ; but it comes in well as a connecting link betweentwo regions, where the peculiar forms of both are specially modified; and is in this respect quite analogous to the great desertzone above referred to.I now proceed to characterize briefly the six regions adoptedin the present work, together with the sub-regions into whichthey may be most conveniently and naturally divided, as shownin our general map.Palcearctic Region.—Thisvery extensive region comprises alltemperate Europe and Asia, from Iceland to Behring's Straits andfrom the Azores to Japan. Its southern boundary is somewhatindefinite, but it seems advisable to comprise in it allthe extra- tropical part of the Sahara and Arabia, and allPersia, Cabul, and Beloochistan to the Indus. It comes downto a little below the upper limit of forests in the Himalayas,and includes the larger northern half of China, not quite sofar down the coast as Amoy. It has been said that thisregion differs from the Oriental by negative characters only ; ahost oftropical families and genera being absent, while there islittle or nothing but peculiar species to characterize it absolutely.This however is not true. The Paleearctic region is wellcharacterized by possessing 3 families of vertebrata peculiarto it, as well as 35 peculiar genera of mammalia, and 57of birds, constituting about one-third of the total number itpossesses. These are amply sufficient to characterize a regionpositively ; but we must also consider the absence of many importantgroups of the Oriental, Ethiopian, and Nearctic regionsand we shall then find, that taking positive and negativecharacters together,and making some allowance for the necessarypoverty of a temperate as compared with tropical regions,the Palsearctic is almost asany other.strongly marked and well defined asSub-divisions of the Palmarctic Region.—These are by no means