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

;chap, x.] THE PALiEARCTIC REGION. 181tions of convenience, dependent on custom and on the more orless perfect knowledge we possess of some of the interveningcountries.Zoological Characteristics of the Palmarctic Region.—The Palaearcticregion has representatives of thirty-five families ofmammalia, fifty-five of birds, twenty-five of reptiles, nine ofamphibia, and thirteen of freshwater fishes. Comparing it withthe only other wholly temperate region, the Nearctic, we findmuch greater variety of types of mammalia and birds. Thismay be due in part to its greater area, but more, probably,to itssouthern boundary being conterminous for an enormousdistance with two tropical regions, theEthiopean and Orientalwhereas the Nearctic has a comparatively short southern boundaryconterminous with the Neotropical region only. This is sovery important a difference, that it is rather a matter of surprisethat the two north temperate regions should not be more unequalin the number of their higher vertebrate forms, than theyactually are.It is also to the interblendingof the Palsearctic with the twoadjacent tropical regions, that we must attribute its possessionof so few peculiar family groups. These are only three ; twoof reptiles, Trogonophidcc and Ophiomoridce, and one of fishes,Comephoridm. The number of peculiar genera is, however, considerable,as the following enumeration will show.Mammalia.—The monkey of Gibraltar and North Africa, andan allied species found in Japan, are now considered to belongto the extensive eastern genus Macacus. The former, however,is peculiar in the entire absence of the tail, and has by manynaturalists, been held to form a distinct genus, Inuus, confinedtothe Palsearctic region.Of bats there are one or two genera (Barbastelhis, Plecotus)which seem to be mainly or wholly Palsearctic, but the classificationof these animals is in such an unsettled state that thedistribution of the genera is of little importance.In the next order, Insectivora, we have almost the entirefamily of the Moles confined to the region. Talpa just entersNorthern India ;and Urotrichus is common to Japan and North-a