226 Geological Society. 
XXXVIII. Proceedings of Learned Societies. 
GEOLOGICAL SOCIETY. 
[Continued from p. 73.] 
April. 6, A PAPER was first read on the genus Tetracaulodon by 
1842. Mr. Koch, communicated by. the President. 
Mr. Koch commences by stating, that a difference of opinion ha- 
ving existed in the scientific world respecting the genus Tetracaulo- 
don of Dr. Godman, and as only a few weeks previously, in a memoir 
read before the Society, the Tetracaulodon was pronounced to be 
simply the male of the Mastodon*, he conceives it to be his duty to 
make public the results of his researches, and which fully prove, in 
his opinion, that the Tetracaulodon is a distinct genus, consisting of 
several varieties. 
The author declares that he has examined with the greatest ac- 
curacy all the inferior jaws of the Mastodon preserved in the collec- 
tions of the United States, but has never seen any specimens with the 
least traces of a tusk; and he adds, that Dr. Hays of Philadelphia, 
after a careful inspection of at least forty jaws, had arrived at the 
same conclusion. According, therefore, to the common laws of na- 
ture, it is highly improbable, observes the author, that the Mastodon 
was such an exception that not one male existed among forty 
females. 
The Mastodon of Philadelphia, Mr. Koch says, is a male, ac- 
cording to the construction and size of the pelvis and the magni- 
tude of the tusks in the upper jaw, yet there are no traces of tusks 
in the lower jaw; and the specimen at Baltimore, which is considered 
to be indisputably a male, is also destitute of inferior tusks. The au- 
thor likewise states that he has uniformly found the jaws of young 
Mastodons to be very rare; that those which he has seen have no 
indications of tusks ; and that he has in his possession the lower jaw 
of a young Mastodon, mentioned by Dr. Hays, which has no tusks. 
Hence he infers that there are young Mastodons, as well as Tetra- 
caulodons. 
Mr. Koch then proceeds to draw attention to ‘some important 
points’ which he believes have not been noticed. 
Admitting, for the sake of argument, that the male Mastodon 
was the possessor of the small tusks only eight or twelve inches 
long in the lower jaw, he says it would have been utterly impossi- 
ble for that animal, with his enormous upper tusks and short neck, 
to have reached the ground with them; yet these small lower tusks, 
he states, show that they were much used in rooting and grubbing, 
and therefore must have belonged to an animal which had equally 
short upper tusks. To substantiate this inference he calls attention 
to three species of Tetracaulodon, the first discovered by Dr. God- 
man, the two others by himself. 
1. Tetracaulodon Godmanii.—This species having been described 
in detail by Dr. Godman, Mr, Koch only points out the great dif- 
ference of the maxillary and nasal bones, as well as the additional 
soramina near the malar bone, which are wanting in the Elephant 
* See p. 56. 
