FALCONER ON THE AMERICAN FOSSIL ELEPHANT. 
99 
pair of points with its outlying appendages, must yield a trefoil or 
complex pattern to the disc of abrasion ; while the inner pair, being 
simple, would yield an elliptical and transverse disc, free from any 
complication. This is the character which distinguishes Mastodon 
Andium from Mastodon Humboldtii. As these species are but im¬ 
perfectly known in England, and one of them still more imperfectly 
represented by specimens, a few remarks upon them may not be 
considered out of place on the present occasion. Although these 
names were vaguely imposed by Cuvier, we are indebted to Laurillard* * * § 
for the first accurate definition of their distinctive characters, con¬ 
firmed by Gervais, upon the fine series of remains brought by 
Weddell from Bolivia.f Both belong to the subgenus Trilophodon . 
In M. Humboldtii , both the inner and the outer divisions of each 
ridge are flanked by outlying tubercles, so that the valleys are 
blocked up, and the mammilla? being channelled vertically, a very 
complex pattern is yielded by the discs of wear; two trefoils are 
produced, separated by a cleft, somewhat as in the molars of Hippo¬ 
potamus , or as it has been happily expressed by Grervais “ Deux 
figures en trifle adossees par leur base.”J The valleys are covered 
with a thick coat of cement, and the lower jaw is destitute of an 
incisive beak. While in M. Andium there is but a single trefoil, 
accompanied by an elliptical transverse disc to each ridge; the 
valleys are sparingly invested with cement, and the symphysis of the 
lower jaw is produced into a long massive and deflected incisive beak, 
as in Mastodon angustidens. This beak, as shown by the young 
animal, is figured by Laurillard in d’Orbigny’s Voyage ; and I have 
seen, at Geneva, the cast of it, as presented by the adult animal. 
The specimen was brought by M. H. de Saussure from Mexico 
(antea p. 56), and the beak in this case bore the base of a very large 
molar on one side.§ Mastodon Humboldtii is found in Colombia* 
Buenos-Ayres, and Brazil; M. Andium chiefly in Chili, Bolivia, and 
Peru; the valley of Tarija, in particular, abounds in remains of this 
species. The reputed Australian molar agrees so closely with 
specimens of M. Andium , brought by Weddell from Tarija, which I 
have studied in the Palaeontological Gallery of the Jar din des Plantes 
at Paris, that I have failed to detect any sufficient character by 
* Alcide d’Orbigny’s ‘ Voyage dans l’Amer. Meridion.’ Geol. p. 144, pi. x„ 
and xi ; and Diet. Univers. d’Hist. Natur. tom viii. p. 30. 
f ‘ Itecherch. sur les Mammiferes Fosssiles de l’Amerique Meridional.’ (Ex¬ 
pedition de Castelnau), 1855, p. 14, PI. v. 
J Op. cit. p. 18. 
§ Laurillard inferred from d'Orbigny’s figure, that although the beak was 
elongated, from its tenuity there were no incisors to the lower jaw in this instance; 
or that, if ever present, they were rudimentary, and had been shed early in life. In 
the specimen figured by Dr. Wyman, showing the lower jaw of an adolescent 
animal, the symphysis is somewhat elongated, but blunt, and there is no appearance 
of its having held incisors. The possession of mandibular incisors may have been 
asexual distinction. (United States’ Australian Expedition, PI. xii. figs. 1 and 2, 
H 2 
