693 
yet there are not found in it two forms of humeri, ulne, radii, 
femora or tibiz, only the merest difference of variety being de- 
tectable; whilst the femora of the Hlephas primigenius associated 
with them are at once recognizable by modifications which might 
be expected to accompany true generic differences in the rest 
of the organization. With the exception of a few bones of the 
Hlephas primigenius, all the other remains of proboscidian Pachy- 
derms in Mr. Koch’s collection, Mr. Owen is of opinion, belong to 
the Mastodon giganteum; and the great skeleton he considers to be 
that of a male individual, on account of the size of the tusks and the 
strongly marked external characters of the principal bones of the ex- 
tremities ; but he points out that the lower jaw belonged to a female, 
and he states that the proprietor acknowledged that it was not 
discovered with the other portions of the skeleton. The true height 
of the animal, taken at the dorsal spines, Mr. Owen estimates at ten 
feet, and the length, from the intermaxillary bones to the end of 
the sacrum, at sixteen feet, or four more than that of the Asiatic 
Elephant in the Hunterian Museum. 
The supposed spinal column of a man fourteen feet high, Mr. 
Owen refers to the Lophiodon: Mr. Koch’s collection also includes 
some interesting remains of the Mylodon Harlani, also portions of 
large species of Bos, Cervus, &c. 
With respect to the use of the lower incisor, Mr. Owen says, if in- 
deed this diminutive inferior tusk were a generic character constantly 
associated in both sexes with the enormous upper tusks, no explana- 
tion could be given of so apparently useless an appendage; but if re- 
garded as a sexual character, there are in the animal kingdom abun- 
dant examples of the functional importance of external ‘distinctions 
in the male ; and such he considers to be the explanation of the per- 
sistent single or prominent tusk in the male Mastodon. Further, 
with respect to the question why two tusks should be originally de- 
veloped, especially in the female, in which neither is to be retained, 
Mr. Owen replies that there is an equal difficulty with respect to 
the two rudimental tusks in the female Narwhal, and of the single 
one in the male; to the abortive incisors in the symphysial part of 
the lower jaw of the Dugong; to the rudimental teeth in the lower 
jaw of the Foetal Whale-bone Whale; and in the upper jaw of the 
Sperm Whale. In these, and many analogous instances, the author 
observes, a structure which is merely sketched out, and is function- 
less in one species, is perfected and performs important uses in an- 
other closely allied. Thus the teeth which are shadowed forth in 
the lower jaw of the Foetal Whale are fully developed in the Cachalot. 
The upper rudimentary maxillary teeth which remain hidden in the 
gum of the Sperm Whale are functionally developed in the Grampus; 
and in like manner in the gigantic Dinotherium, discovered by Dr. . 
Kaup, is exhibited the full and functional development of the infe- 
rior rudimental tusks of the Mastodon. 
The molar teeth of the Mastodons offer, Mr. Owen says, a beauti- 
ful transitional modification connecting the lamellated structure of 
