714 
Mr. Murchison observes, in the composition of its solid: contents 
from many of the red or brown soils of England. iat 
3. Origin of the Tchornot Zem.—In speculations on the origin of 
this deposit, the author dissents entirely from the opinion that it is 
due to decayed forests, as it never contains, even when exposed to 
the depth of 20 feet, any traces of trees, roots, or vegetable fibres, 
not connected with the existing vegetation. On the contrary, he 
believes it to be a subaqueous accumulation, but he objects to the 
views entertained by those geologists who place it, as respects its 
mode of production, on a parallel with the loess of the Rhine, or 
with the upper diluvial mud of Belgium, France and Germany ; not 
having anything in common with the latter, and differing from the 
loess by the absence of well-preserved fresh water and terrestrial 
shells indicating fluviatile or lacustrine origin. The loess, moreover, 
is never found on high plateaux ; but Mr. Murchison does not dis- 
sent from the belief that the two deposits may have been pro- 
duced at nearly the same epoch. He is therefore induced to con- 
sider the Tchornoi Zem as a submarine formation accumulated gently 
at the bottom of a sea undisturbed by any violent current, and be- 
ond the range of those operations which spread out the northern 
drift. The absence of marine shells, he says, is only a negative 
objection, and not to be opposed to the evidence afforded by the 
widely different nature of the deposits at considerable levels, far 
above the drainage of the country or the action of any body of wa- 
ter which could occupy the valleys. Lastly, he ascribes the black 
colour of the earth to the state of decomposition of the vegetable 
matter- originally diffused through the mud which now forms the 
fertile Tchornoi Zem of Russia. 
April 6.—Col. AlexanderFisher Macintosh, K.H.,of Antermoney, 
near Glasgow; Josiah Rees, Esq., of the Ordnance Geological Sur- 
vey of Great Britain; John Birkett, Esq., Demonstrator of Anatomy 
at Guy’s Hospital ; and Joseph Dickinson, Esq., Mining Engineer, 
of Dowlais, Glamorganshire, were elected Fellows of this Society. 
A paper was first read on the genus Tetracaulodon by 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 
