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 2?7'i7nigemus 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 J/as^Of/o?i Andium and Mastodon 
Humholdtii 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 oat i 
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. J ulian. 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 wisli 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 Humholdtii undeserved, took place long prior to the up- 
heaval, through slow volcanic agency, of the Andes. This species, for 
which a more appropriate name miglit 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. 
