1882.] 
459 
[Merrill. 
Nos. 163 and 174 are, indeed, highly altered rocks as Zirkel evi- 
dently did find for he says so (pp. 86, 89 of Report). Mr. Wads- 
worth says that he is inclined to consider the other diorites of 
Zirkel as belonging to the granitic and felsitic rocks. 1 I will only 
state that I do not agree with him in this opinion and pass on to 
a few other cases of some interest where Mr. Wadsworth has « 
sjiecified numbers separately. 2 
On page 258 (second paper) Mr. Wadsworth writes : “ Of No. 
168 (1389) Zirkel stated: ‘ The rock has no mica’ (VI, p. 87), 
but the writer found mica in it.” I searched carefully in the 
thin section for mica but found none. On the same page it is 
also written: “So, too, quartz was found in No. 187 (2723) 
although Zirkel says it contains no quartz.” Upon examination, 
I think that the rock carries no quartz. It would at least appear 
probable from this that these ingredients are not present in 
sufficient quantities to contribute at all to the character of the 
rock. 
The syenites of Zirkel’s Report are considerably decomposed 
as Mr. Wadsworth has said; the only two which are mentioned 
are, on this account, not very satisfactory specimens. Professor 
Zirkel says (Report, p. 81) : “ Among the examined rooks of the 
Fortieth Parallel, genuine characteristic syenites resembling the 
classic German ones from the Plauschner Ground near Dresden 
and from Weinheim on the Bergstrasse are extremely rare. 
Properly there is only one really old syenite in this region. It 
forms the main mass of Cluro Hills, Cortez Range, Nevada.” 
Tins is No. 152. Zirkel has given a very detailed description 
of it, which seemed to me a very truthful and accurate one, and 
he calls it a syenite. Mr. Wadsworth hrs given nothing that can 
be called a description of it, and names it an old altered andesite. 3 
The rock seems to me to be a syenite in accordance with Pro- 
fessor Zirkel’s description. 
1 Page 257, second paper. 
2 In the case of the mica diorites, Nos. 169 and 170, Mr. Wadsworth thinks that there 
must have been some mistake made in the hand specimens , since they show but little 
trace of mica, and resemble some metamorphic schists (these Proc., Vol. xxi, p. 258). 
He might have added that there was a mistake as to the thin sections also. Slide No. 
169 corresponds to the hand specimens perfectly and shows but little mica, while the 
brown hornblendes often show good cleavage. Section No. 170 is too thick to be of 
service. 
8 These Proceedings, Vol. xxi, p-. 257. 
