472 



THE GEOLOGIST. 



species. This, when a larger series of specimens is examined, proves 

 to have been an imperfect and erroneous induction. There is no 

 appreciable difference between the two species in this respect. The 

 alleged symphysial difference I cannot regard one of specific dissimi- 

 larity. The differences which we observe in the symphyses of the 

 Elephas primigenius or in the Elephas antiquus are fully equal to 

 those between the same bone in the two South American species. 

 Specific characters can never be founded on parts which are so liable 

 to adaptive change as the symphysial angle of a great trunk-bearing 

 beast. 



From a careful consideration, then, of the whole aspect of this ques- 

 tion, I am of opinion that the species Mastodon Andium and Mastodon 

 Humboldtii are not specifically distinct. The Guanaco which climbs 

 the summits of Tupungato, Aconcagua, or Tata- Jachura, is the same 

 animal as the Guanaco which manages to survive in the plains near 

 Puerto Deseado, in Eastern Patagonia. I have already pointed out 

 in your pages, in the " Geologist" for August, that the Tarija Macrau- 

 chenia, like that of Corocoro, was in all probability the same species as 

 the Macrauchenia Darwin found at Port St. Julian. Professor Owen 

 said a few weeks ago to the British Association : — " The cardinal 

 defect of speculators on the origin of the human species is, the as- 

 sumption that the present geographical condition of the earth's surface 

 is antecedent to, or at least co-existent with, the origin of such species." 

 The application of this erroneous mode of thought has been by no 

 means limited to Ethnology, and it has been through an analogous 

 error that the existence of two species of Mastodon in South America 

 has been asserted, upon geographical grounds alone. 



The conclusion which I would wish to impress upon the minds of 

 your readers, is that one solitary species of Mastodon existed in South 

 America during the Pliocene age. That the distribution of this 

 species, for which the name of Andium is obviously inappropriate, 

 and that of Humboldtii undeserved, took place long prior to the up- 

 heaval, through slow volcanic agency, of the Andes. Tins species, for 

 which a more appropriate name might be suggested, flourished over 

 nearly the whole of South America, and like the Megatheria, Mylodons, 

 Glyptodons, Macrauchenice, and Toxodons, has passed away, and leaves 

 no evidence to apprise the geologist of the former existence of elephan- 

 tine animals in South America except a few scattered molars and 

 vertebrae, brought down by alluvial deposits from the heights of the 

 mighty mountains in which, possibly, further remains may be em- 

 bedded. 



I remain, Sir, your obedient servant, 



Charles Carter Blake. 



