MATTHEW, CLIMATE AND EVOLUTION 317 



While Doctor Scharff's interpretation of the data is based upon funda- 

 mentally different principles above noted, and his statements as to fossil 

 distribution are often inaccurate or incomplete, yet the numerous dis- 

 tributional data which he presents of modern invertebrates are of great 

 interest, and, if interpreted along the lines which I have used, they fall 

 completely into line with the vertebrate evidence. We cannot usually 

 indeed check the conclusions drawn from modern distributional relation- 

 ships by the fossil record. Many groups are altogether unknown, and 

 the record in others is vei-y scanty, but the same general relations clearly 

 apply. The survival in Western Europe on one side, in southeastern 

 North America on the other side, of a somewhat primitive cycle of Hol- 

 arctic distribution ; the survival in the Mediterranean region on one side, 

 in Central America and the Antilles on the other, of a more primitive 

 cycle ; of a still more primitive cycle in Africa and South America ; and 

 the progressively greater amount of divergent or parallel specialization 

 in the survivors of the earlier cycles; the antique and fragmentary char- 

 acter of the fauna^ of the oceanic islands, progressively more so in pro- 

 portion to their sniallness and isolation — all these conform to the verte- 

 brate distribution. And with invertebrates as with vertebrates, every 

 year adds to the number of the types which, while now limited to the 

 peripheral continents and oceanic islands and highly discontinuous in 

 their range, are shown to have inhabited formerly the central Holarctic 

 i-egion. It appears that many, one might perhaps say most, invertebrates 

 are more readily transported across ocean barriers than vertebrates, espe- 

 cially mammals, even making due allowance for their greater antiquity. 

 This also we should expect. 



I do not think it necessary to catalogue the errors or inaccuracies in 

 presenting the evidence afforded by fossil vertebrates. Such errors are 

 unavoidable in a subject of so broad a scope, and excusable enough, if 

 they do not lean too much to one side. I shall cite but one instance, 

 and this in justice to my distinguished confrere Professor Deperet. 

 Doctor Scharff concludes his summary of the North American records 

 of the Evolution of the Horse with the following remarks :^^^ "And yet 

 not a single transition from one genus to the other seems to be known. 

 No wonder that one of our foremost paleontologists exclaims, 'The sup- 

 ])osed pedigree of the horse is a deceitful delusion, which simply gives 

 us the general process by which the tridactyl foot of an ungulate can be 

 transformed in various groups into a monodactyl foot in view of an 

 adaptation for speed, but this in no way enlightens us on the paleontolog- 

 ical origin of the horse.' " Such a statement, coming from so excellent 



i^^Op. cit., p. 147. 



