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

192 ZOOLOGICAL GEOGRAPHY. [part hi.fact, to these, and the numerous lesser mountains and hillswhich everywhere diversify the surface of Europe, that thevariety and abundance of its animal life is greatly due. Theyafford the perennial supplies to rivers, and furnish in theirvalleys and ever varying slopes, stations suited to every formof existence. A considerable area of Central Europe is occupiedby uplands of moderate elevation, a comparativelysmall portion being flat and marshy plains.Most of the northern and much of the central portions ofEurope are covered with vast forests of coniferous trees ;andthese, occupying as they do those tracts where the winter ismost severe, supply food and shelter to many animals who couldnot otherwise maintain their existence. It is probable thatthe original condition of the greater part, if not the whole, oftemperate Europe, except the flat marshes of the river valleysand the sandy downs of the coast, was that of woodland andforest, mostly of deciduous trees, but with a plentiful admixtureof such hardy evergreens as holly, ivy, privet, and yew. Asufficient proportion of these primeval woods, and of artificialplantations which have replaced them, fortunately remain, topreserve for us most of the interesting forms of life, whichwere developed before man had so greatly modified the surfaceof the earth, and so nearly exterminated many of its originaltenants. Almost exactly in proportion to the amount ofwoodland that still remains in any part of Europe, do wefind (other things being equal) the abundance and varietyof wild animals; a pretty clear indication that the originalcondition of the country was essentially that of a forest, acondition which onlyof the north.now exists in the thinly inhabited regionsAlthough the sub-region we are considering is, for its extentand latitude, richly peopled with animal life, the number ofgenera altogether peculiar to it is not great.There are, however,several which are very characteristic, and many species, bothof the smaller mammalia and of birds, are wholly restrictedto it.Mammalia.—The genera wholly confined to this sub-region are