770 
neighbourhood of Quebec, Mr. Logan proceeds to describe briefly the 
circumstances under which four of the same species of mollusks were 
found near Montreal. The spot from which they were principally pro- 
cured is stated to bear very much the character of a raised beach, and 
was determined barometrically to be 430 feet above the Montreal 
harbour, or about 46Q feet above the Atlantic, the greatest height 
at which Captain Bayfield’s specimens were found, being 300 feet 
above the level of the Gulf. The above altitude of the Montreal 
deposit is further stated to be 240 feet above the level of Lake On- 
tario and 75 feet above the Falls of Niagara, but to fall short of 
Lake Erie by about 105 feet. The four ascertained species obtained 
by Mr. Logan are the following :— 
1. Saxicava rugosa, very abundant to the north of the road to the 
Céte de Nieges, in a bed of coarse sand inclined conformably with 
the side of the hill, and which has, above it, a layer of pebbles and 
small boulders, The altitude of this position is 430 feet. ‘The shell 
occurs also, but not abundantly, above the village of St. Henry, on 
the road to Lachine, on the top ef an elevated terrace along the bank 
of the St. Lawrence, and 120 feet above the river; it has been also 
obtained on the same terrace at Logan’s Farm. 
2. Tellina Groenlandica, which is found abundantly at St. Henry, 
and to a less extent on Logan’s Farm and on “ the Mountain.” 
3. Tellina calcaria—One valve of this shell was picked up on 
“the Mountain.” : 
4. Mya truncata.—Several hinges of this species were obtained at 
St. Henry. 
5. Mytilus—-A broken valve was found on “ the Mountain.” 
The first four fossils, Mr. Logan says, he has been informed, were 
found by Mr. Murchison and M. de Verneuil at Ust Vaga, 250 miles 
from the White Sea, and 130 feet above its level. He also alludes 
to Mr. Lyeil’s comparison of the Quebec shells with species which 
occur at Uddevalla. 
A communication was afterwards made by Dr. Grant, F.G.S., 
“On the Structure and History of the Mastodontoid Animals of 
North America.” ; 
The chief object of this communication was to point out, the 
structural differences and zoological distinctions of the Mastodons 
and Tetracaulodons of North America ; and the inquiries were in- 
stituted in consequence of the favourable opportunity afforded by the 
temporary exhibition, in this metropolis, of Mr. Koch's large collec- 
tion of organic remains from the State of Missouri, consisting prin- 
cipally of the relics of these two genera. 
After pointing out the important applications of the study of these 
remains, and the geological relations of Mastodontoid animals, and 
the discordant opinions of zoologists as to their specific distinctions, 
Dr. Grant entered into extended details regarding the general struc- 
ture and the peculiarities of the skeleton in the three principal 
Mastodontoid genera, Mastodon, Tetracaulodon, and Deinotherium, 
