150 procp:edings: boston society natural history. 
elusions as to the goolofiical history of this ro^rion with any hip;h 
(J('{i;n'(' of accuracy. 
It is interesting to note in this connection that on the island of 
Anticosti, which Hes in the St. Lawrence only 70 miles from the 
(Jaspe peninsula, there is an unbroken series of Ordovician and 
Silurian strata 2372 feet thick. ^ The rocks of the two systems 
cannot be differentiated on structural or lithological grounds; 
the only guide is palaeontology. In fact there is yet considerable 
doubt as to where the dividing line should be drawn. This 
state of affairs is not what one would expect a few score of miles 
from the site of such extensive mo\mtain-building as is supposed 
to have closed the Ordovician. There is no unconformity, no 
appreciable change in the nature of the sediment — or, at least, 
none that would indicate nearby uplift — and apparently the 
seas themselves were little disturbed, for several species are com- 
mon to the Ordovician and the Silurian rocks. The evidence 
which should be present on Anticosti is lacking. 
Central New England. 
Three localities in central New England have been cited as 
affording evidence for the point in question, all of them in the 
meridional system of troughs connected with the Connecticut 
River valley. These localities are Lake Memphremagog on the 
Vermont-Quebec line, the Ammonoosuc district around Little- 
ton, N. H., and Bernardston, Mass. 
Lake Memphremagog. — No evidence of an erosional uncon- 
formity could be found in any of the writings of Ells^ on this 
region, nor in the more recent papers by Robert Harvie.^ The 
geological structure is evidently very complicated, if the diver- 
sity of interpretations is any guide. Ells, in 1892, thought that 
the Silurian was underthrust beneath the Ordovician, as shown 
by the fossils, while Harvie, in 1914, states that the Silurian 
iSchuchert, C, and Twenhofel, W. H. Ordovicic-Siluric section of 
the Mingan and Anticosti Islands, etc. BuU. Geol. Soc. Amer., vol. 21, 
p. 684, 1910. 
^EUs, R. W. Ann. Rept. Geol. Surv. Canada 1886, p. 12 J, 1887; 
Ann. Rept. Geol. Surv. Canada 1896, p. 12-15J, 1898; Trans. Roy. [Soc. 
Canada, vol. 2, sect. 4, p. 122, 1892. 
^Harvie, Robert. Summ. Report Geol. Surv. Canada 1911, p. 286, 
1912; 1913, p. 212, 1914. 
