Wadsworth.] 
274 
[October 19, 
muscovite mica schist is a paragonite schist, that a greenish 
altered groundmass is olivine, that olivine, quartz, and biotite 
are absent when they are present, etc., etc. are things the responsi- 
bility of which he can not escape. 
It would seem that evidence enough has been brought forward 
from volumes I, II, III, and VI to show that Professor Zirkel 
accepted Mr. King’s statements, and outside of the simple and 
quite often inaccurate descriptions of the specimens and sections, 
registered the rocks in general as they were given him. 
It would seem that the present writer, in the light of all that is 
given before, as well as much not given, had the right to think 
for himself and to reject the dicta of Messrs. King and Zirkel 
when the facts were not consonant. It is not to be taken that I 
endorse all the determinations of Professor Zirkel to which I 
have not here objected, since in many others agreement does not 
exist. But since my examination was made in 1878 for a differ- 
ent purpose than that of this paper, it is better to defer other 
statements until at least a desirable re-examination can be made 
of the collection discussed. It is possible that in some cases the 
writer’s views would be modified on a re-examination, as regards 
the theoretical belief under what species a specimen belongs. 
Although only a small portion of the original paper is given in 
the present article, it is hoped that enough has been presented to 
answer the questions arising out of that portion of my preceding 
paper devoted to the Fortieth Parallel Exploration, and to show 
that Mr. Merrill misstates my views in almost every particular. 
ON THE RELATION OF THE QUINCY GRANITE TO THE 
PRIMORDIAL ARGILLITE OF BRAINTREE, 
MASSACHUSETTS. 
BY M. E. WADSWORTH. 
Since the argillite in the immediate neighborhood of the Para- 
doxides quarry of Braintree, lying north and south of Hayward’s 
Creek, is the only rock in the Boston Basin whose age is definitely 
known, the relations to it of the adjacent rock is a very interest- 
