120 
Lyell on the authority of Dr. Beck : Mya truncata (var.), found fossil 
in Bute, and living in the St. Lawrence; Mya arenaria and Saai- 
cava rugosa, recent in the Gulf of St. Lawrence; Tellina calcarea, 
fossil at Bute; Tellina Grenlandica, which exists in the Gulf of St. 
Lawrence and at Icy Cape; Mytilus edulis; Pecten Islandicus, 
found living in the North Sea, and fossil in Scotland; Terebratula 
psittacea, which occurs on the coasts of Greenland and the Feroe 
Islands ; also at places intermediate between them and the entrance 
of the Baltic; Natica clausa, recent in Greenland and fossil at Ud- 
devalla; Scalaria Grenlandica, S. borealis, Tritonium fornicatum, T. 
Anglicanum, all now existing in the Greenland seas, the last being 
considered by some authors as a variety of Buccinum undatum, and 
the T. fornicatum being also found living on the Irish coast, and 
fossil at Dalmuir and in Scotland. On the other hand, many of 
the shells living in the Gulf of St. Lawrence and most conspicuous 
for their size, are wanting in the collections of fossils hitherto ob- 
tained, as the Mactra solidissima, Erycina Labradorica, Purpura, allied 
to P. Lapillus, Natica Heros, and Rostellaria occidentalis. 
The torrents and rivers which flow into the St. Lawrence wash 
down annually into that estuary great numbers of tertiary fossil 
shells, so that they become mingled with the living testacea. The 
latter, however, may be generally distinguished by retaining their 
colour, animal matter, or ligaments; but it is more difficult to di- 
stinguish those shells which have been derived exclusively from the 
tertiary beds. Nevertheless, Mr. Lyell has little doubt in assigning 
to them the specimens of Balanus Uddevallensis and the Fusus 
_allied to F. lamellosus, which have been dredged up off Cape Bic, as 
they are all in the same condition as the Beauport fossils. 
The climate of Canada being now excessive, it is natural to find in 
the Gulf of St. Lawrence many northern and arctic species, without 
any mixture of tropical forms, for the latter cannot resist severe cold, 
though they range far towards the southern polar latitudes, where 
a low mean annual temperature prevails. Mr. Lyell, therefore, con- 
ceives that during the period immediately antecedent to the present, 
the climate of Canada was even more excessive than it is now; and 
that the shells resembled still more closely the small assemblage 
now living in high northern latitudes. He is also of opinion, that 
this extreme cold may have coincided with the era of the principal 
transportation of erratic blocks, an inference supported by the 
masses of rock irregularly dispersed among the clay. He further be- 
lieves, that a more equable though cold climate may have preceded 
immediately that condition; and that there may have been more 
than one oscillation of climate at the modern period, the last having 
been connected with the geographical changes which upheaved the 
shelly deposits of Canada 200 feet above the level of the St. Law- 
rence, and converted them from submarine deposits to dry land. 
An extract was next read from a letter addressed to Dr. Fitton 
by Herr Roemer, of Hildesheim, on the Wealden of the North of 
Germany. 
