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Show 326 GEOGRAPHICAL DISTRIBUTION. [CHAP. XI. difficult to avoid belie-ving that th~ temperature of the whole world V{as at this period sim~ltaneously cooler. But it would suffice for my purpose, If. the temperature was at the same time lower along certain broad belts of longOitnu dthei. s view o· f the whole 1 t f b d ~orld, or at eas o roa longitudinal belts, having been simultaneously colder fron1 ole to pole, much light can b~ throw~ on the pres.ent ~istribution of identical and alhed species. In Amenca, Dr. Hooker has shown that between forty a:nd fifty ?f the flowering plants of Tierra del Fuego, forming no Inconsiderable part of its scanty flora, are ~ommon to Europe, enormously Temote as · thes~ two points are; and th~re are many closely allied spemes. On. the lof~y mounta;Ins of equatorial America a host of pecuh~r species belo!1gm~ to European genera occur. On the highest mountains of Brazil, some few European gen~ra :vere fo"?-nd by Gardner, which do not exist in the wide Inter~enin~ hot countries. So on the Silla of Caraccas ~he Illustrious Humboldt long ago found species belonging t? geneTa ch~r~cteristic of the Cordillera. On the mountains of Ab:rssinia, several European forms and some few representatives of the peculiar flora of the Cape of Good I-Iope occu;·. At the Cape of Good Hope a very few European spemes, believed not to have been introduced by man, and on the mountains, some few represen:ative Eu~·opean forms ar.e found which have not been discovered 1n the Inte~tropical p~rts of Africa. On the Hi~alaya, and on. the Isolated mountain-ranges of the peninsula of India, on the heights of Ceylon, and o~ the. volcanic cones of Java, many plants occur, either Identically th~ same or re~resenting each other, and at ~he san;e t1me . representing lants of Europe, not found In the Intervening ?ot lowfands. A list of the genera collecte~ on the loftier ~ea~s ·of Java raises a picture of a collection made on a hill 1n Europe ! Still more striking is the fact that southern Australian forms are clearly represented by plants ~·owing on the summits of the mountains of Borneo. orne of these Australian forms, as I hear from Dr. Hooker, extend along the heights of the peninsula of Malacca, and CHAP. XI.] DURING THE GLACIAL PERIOD. 327 are thinly scattered, on the one hand over India and on the other as far north as Japan. .. On the s.outhern mountains of Australia, Dr. F. :Mul~er has ~Iscovered several European species; other spemes, not ,r~1troduced b:t man, occur on the lowlands; and a Ion~ bst can be given, as I am informed by Dr. :_Hooke:, of Eur?poan g~nera, found in Australia, but. not m the I~termediate tornd r~.B'ions. In the admirable' Introduction to the Jfl?ra of 1~ ew Zealand,' by Dr. IIooker, analogous and striln:ng facts are given in regard to the plants of that large Island. lienee we see that throughout th~ world, the plants growing on the more lofty mountains, and on :he temperate lowlands of the northern and southern hemispheres, are eometiines identically the same ; but ,they are much oftener specifically distinct, though , related to each other in a most remarkable manner. This brief abstract applies to plants alone : some strictly analogous facts could be given on the distribution of terrestrial animals. In marine productions, similar cases occur; as .an example, I may quote a remark by the highest authority, Prof. Dana, that "it is certainly a wonderful fac~ that New Zealand should have a closer resemblance In Its crustacea to Great Britain, its antipode than to any other part of the world." Sir J. Richardson' also speaks of t~e re-appearance on the shores of New Zeala~d, Tasmania, &c., of northern fonns of fish. Dr. Hooker informs me that twenty-five species of Algre are common to N e~ Zealan~ and to _Europe, but have not been found in the 1ntermed1ate tropical seas. It should. be observed that the northern species and forms found· In the southern parts of the southern hemisph~ re, and on the mountain-ranges of the intertropical regwns, are not arctic, but belong to the northern tempe~ ate zones.. As Mr. H. C. Watson has recently remarked, Af· receding from polar towards equatorial latitudes, the . ~1ne or mountain :floras really become less and less arctic. Many. of the forms living on the mountains of the Warmer regions of the earth and in the southern hemisphere are of doubtful value, being ranked by some natu- |