KiNAHAN — Killary Bay and Slieve Partry Silurian Basin, 709 
As to the assertion in reference to the distinguishable topographical 
features, they may possibly hold good in Scotland, but certainly they 
do not hold good in Ireland, and far less in America. In portion of the 
Devonian regions of Cork and Kerry the description given above is 
applicable, while in portions of the Donegal metamorphic area (none 
of which rocks Dr. Geikie will allow to be pre-Cambrian) there are 
topographical features identical with those of the Algonkian district, 
north of Lake Superior, if we may be allowed to compare small things 
with great. As far as I have seen in America, Ireland, and Scotland, 
the most rugged and roughest districts are schist regions, especially if 
associated with these are large areas of hornblende or allied rocks — 
while the gneiss and other granitoid -rock regions, in comparison with 
them, are comparatively tame. As a rule, as far as I saw, the Lauren- 
tian regions in Canada are much less rugged than the Huronians and 
Superior Western district [Classification of the Early Cambrian and pre-Cambrian 
Formations, U. S, Geological Report, 1885 a^id 1886) as follows: — 
Systems. Groups. 
Carboniferous. 
Palaeozoic, 
Devonian. 
Silurian. 
Cambrian (Lower Silurian), 
iKeweenawan. 
Huronian. 
Other groups. 
. f Laurentian, including Upper 
\ Laurentian. 
Although this classification has been published in the U. S. American Official 
Reports (1885-86), I learn from Professor Van Hise that for Agnotozoic the Survey 
has now substituted the territorial name Algonkian ; while Dr. Lawson, of the 
Canadian Survey, states that his name Ontarian, as it had a priority, ought to be 
adopted. 
As to the term, Archaean, Irving, in his Table, restricts it to Logan's Lauren- 
tian ; but Dana, the originator, in a letter to me states that he originally proposed it to 
include all the American pre-Cambrian strata. At the same time he points out that 
recent researches might modify its full original scope ; because the organic remains 
found in the Nova Scotian pre-Cambrian rocks and the supposed organic remains 
in the Penokee Gogebig iron region (Huronian) would in a measure make it inap- 
plicable. 
The Scotch and Mayo rocks referred to by Dr. A, Geikie, as far as my expe- 
rience goes, are in general characters very similar to the East Quebec and Vermont 
rocks (Algon/cians) and those of the Lake of the Woods series [Ontarians) ; and if 
these are the equivalent of the Scotch and Mayo rocks, the European rocks are far 
from being the oldest known, as there is a profound break between the Algonkians 
and the Huronians, and a second between the Huronians and the Laurentians, 
