368 Correspondence . LJune, 
I have myself carefully examined them since then from Ver- 
mont to Gaspe, and am in a position to assert and to prove that 
the whole evidence is in favour of their pre-Cambrian age. 
Physically and mineralogically they correspond with the Hu- 
ronian series of Sir William Logan, which some authors have 
asserted, without any sufficient evidence, rest unconformably on 
the Laurentian : this assertion Sir William Logan himself never 
ventured to make, and the truth of it no member of this Survey 
has yet been able to confirm, though many miles of both Series 
have been examined from Nova Scotia (Cape Breton) to Lake 
Winnipeg. The result has been, in the East, to cause us to 
give up the attempt to define them as separate formations, and 
to classify them all simply as pre-Cambrian. A similar result 
has, I understand, attended a similar attempt on the Pennsyl- 
vania Geological Survey. I may add that I have no doubt what- 
ever of the correctness of recent views respecting the schists, 
&c., of Anglesea and Caernarvon, which I mapped on the British 
Survey with Sir A. C. Ramsay some thirty-five years ago, namely, 
that they are likewise of pre-Cambrian age. They correspond 
exaCtly with the so-called altered Quebec group of Logan ; but 
here the evidence of stratigraphical position is much more dis- 
tinct, — indeed it is so plain along a line of more than 150 miles 
as to leave no reasonable doubt on the matter. 
Some day we may discover a sound basis of separation for 
Laurentian and Huronian, but as yet this has not been done in 
Canada, unless mere mineralogical differences in groups of beds 
are to be taken as such, — a feature which appears to be also 
characteristic of the supposed Laurentian rocks of Ireland. 
The subject is one I take great interest in, and, though I have 
written but little about it, I have perhaps studied it over a wider 
geographical range than any other living geologist. — I am, &c., 
Alfred R. L. Selwyn. 
A BOLIVIAN SAURIAN. 
To the Editor of the Journal of Science. 
Sir, — The “ Anglo-Brazilian Times,” March 24th, 1883, says 
that “ the Brazilian Minister at La Paz, Bolivia, has remitted 
to the Minister of Foreign Affairs in Rio photographs of drawings 
of an extraordinary Saurian killed on the Beni after receiving 
thirty-six balls. By order of the President of Bolivia the dried 
body, which had been preserved at Asuncion, was sent to La Paz. 
It is 12 metres long from snout to point of the tail, which latter 
