28 



SCIENCE. 



[N. S. Vol. V. No. 105. 



gles of India and Burma, and the Arctic tun- 

 dras of Siberia." It may be poetic license, but 

 hardly scientific truth, to speak of the tiger as 

 an inhabitant of ' Arctic tundras.' And Mr. 

 Lydekker must be aware that the northern 

 tiger differs so markedly from the southern that 

 it is regarded by some naturalists as a distinct 

 species and has received a distinctive name. 

 Our American puma also is a composite beast, 

 differing widely in different parts of its range. 



Other cases of the same sort that have been 

 often cited are those of the wolf and ermine 

 weasel. In discussing this subject five years 

 ago I said : ' ' With the possible exception of 

 the gray wolf, not a single species of mammal 

 ranges throughout the Sonoran and Boreal 

 Zones, though a number are common to the 

 Upper Sonoran and Lower Boreal (Canadian) ; 

 and in the case of the wolf it is almost certain 

 that comparison of specimens will show the 

 animal of the southern United States and 

 Mexico to be perfectly distinct from that of 

 Arctic America. The ermine is another species 

 of phenomenal though less extensive range, if 

 it is really true that the weasel inhabiting the 

 shores and islands of the Polar Sea is specifially 

 identical with that found in the more elevated 

 parts of the Southern States — an assumption I 

 cannot for a moment entertain."* 



Since this was written it has been found that 

 the northern and southern wolves are very 

 different, and that the weasels inhabiting North 

 America from the Arctic barren grounds to 

 Mexico belong to no less than five different 

 species, each characteristic of a particular cli- 

 matic belt ! 



That Mr. Lydekker is a ' lumper ' of species 

 is well known, and is exemplified by his state- 

 ment that in North America we have only a 

 single species of porcupine (Erethizon) and only 

 one of little spotted skunk (Spilogale) ! The 

 way he unites European and American mam- 

 mals has been pointed out in this Journal in re. 

 views of his earlier works. -j- In the present 

 volume he maintains his reputation in this di- 

 rection, stating or implying that Eurasian and 

 American wolverines, martens, wolves, foxes, 



*Proo. Biol. See. Washington, VII., 48, April, 1892. 



tSee Science, April 5, 1895, pp. 387-389 ; July 5, 

 1895, pp. 18-21. 



bears, lynxes, moose, reindeer and sheep are 

 not specifically separable. With respect to the 

 sheep he says : ' ' The Kamschatkan wild sheep 

 is so closely related to one race of the big-horn, 

 or Rocky Mountain sheep that it is very ques- 

 tionable whether the two are really entitled to 

 specific distinction." If Mr. Lydekker will 

 take the trouble to glance at the skulls of these 

 two animals, or even at the rather crude figures 

 published by Guillemard in the Proceedings of 

 the Zoological Society of London for 1885 (pp. 

 676-677), I do not think his faith in their dis- 

 tinctness will ever again be shaken. 



Of the lesson to be learned from cases of dis- 

 continuous distribution, Mr. Lydekker states : 

 ' ' Examples of ' discontinuous distribution ' 

 among genera are of the very highest import 

 to the science, since they clearly indicate that 

 some of the lands lying between its present dis- 

 connected distributional areas must have for- 

 merly been the habitat of the genus, and thus 

 enable important conclusions to be drawn as to 

 the former land connections between such 

 areas. ' ' But at the end of the book he implies 

 his belief in the dual origin of both species and 

 genera. He says : ' ' The suggestion that Equus 

 has thus been independently evolved in the 

 two areas has been already mentioned, and 

 this idea receives support from some very re- 

 markable observations recently made on the in- 

 vertebrates inhabiting certain European and 

 North American caves * * * if animals which 

 appear to belong to one and the same species 

 can be proved to have had a dual origin in the 

 one case, it can scarcely be considered impos- 

 sible that similar instances may occur in the 

 other. And if such dual origins exist among 

 species, there is surely no reason why they 

 should not occasionally occur in the case of 

 genera. It would, therefore, seem by no means 

 improbable that the species of the genus Equus, 

 which inhabited the eastern and western halves 

 of the northern hemisphere during the close of 

 the Tertiary period, may have been evolved 

 from the closely allied but separate ancestral 

 equine stocks." 



Respecting the geographic origin of types, 

 the author holds the extreme view that "at least 

 a very large proportion of the animals that have 

 populated the globe in the later geological 



