BLAKE — DISTRIBUTION OF MASTODON. 
471 
polar limit of the Proboscidea is 32 degrees South ; and we have evi- 
dence of an American Mastodon in nearly the same latitude. But, 
upon the supposition that the state of the South American continent 
was analogous to the existing one, ordinary readers can hardly realize 
the fact that a species of elephant should have existed amongst an as- 
semblage of high hills, at an elevation of 2300 feet above the level of 
the sea. The numerous indications, however, of volcanic action in 
the neighbourhood of Tagua-tagua afford us a clue to explain the 
cause by which such alteration of the aspect of the country as has 
been manifestly produced, must have been occasioned. The fragments 
of bone which Mr. Bollaert was enabled to discover, consisted of por- 
tions of a femur and tibia ; those which Don Claudio Gay figures, are 
the atlas, tibia, calcaueum, fourth metacarpal, and, finally, the almost 
entire mandible. 
De Blainville is of opinion that evidence is wanting that the Mas- 
todon Andium and the Mastodon Humholdtii are different species. 
Laurillard (D'Orbigny, " Diet, Hist. Nat.," art. Mastodon) denies this 
theory, and points out that the angle formed by the symphysis in 
Humholdtii is short, and otherwise differs from the same structure in 
Andium. I am aware of the fact that Cuvier founded the species 
Humholdtii upon a specimen alleged to be brought from Con- 
ception by Baron Humboldt, a place never visited by him ; but I 
am inclined to think that some error or misapprehension exists as 
to this statement. The Andes at present act as an effectual barrier 
to prevent the migrations of large species of animals across them, and 
unless the upholder of the theory that the La Plata and Chile species 
of Mastodon are of the same species, accepts also the hypothesis of their 
existence in South America antecedent to the present disposition 
of the continent and upheaval of the Andes, he cannot hold the 
possibility of accidental migration of elephants over the snowy range. 
If, however, both Andium and Humholdtii are modified descendants of 
Boine original progenitor, which existed in South America before the 
upheaval of the Andes, the difificulty in some way disappears. But 
upon examination of the specimens of Mastodon Andium in the 
British Museum collection, the habitat from which they are un- 
doubtedly derived is Buenos Ayres. I have no doubt whatever of 
the perfect accuracy of Mr. G. K. Waterhouse's statement as to their 
being geographically derived from that country, and I cannot close 
my eyes to the fact, that we have here evidence of the existence of 
Mastodon Andium in a spot in which Laurillard, who so confidently 
assigned the western side of the Cordilleras as its habitat, never 
dreamed. 
Are the differences between Andium and Humholdtii of specific 
value 1 I think not. From inspection of a large series of teeth of 
Mastodon longirostris (angustidens) I can confidently declare that 
there is not greater difference between the teeth of Andium and 
Humholdtii than between the many varieties of the narrow-toothed 
Mastodon. When Cuvier founded the species Humholdtii, he thought 
that there was a difference of size between the molar teeth of the two 
