Geology and Mineralogy. 155 
tangular nervation of the genus. The principal yerves are dichoto- 
mously forked, and it seems. more likely that the fragment repre- 
sents a new species of Dictyophylhun. 
A notice of this elegant volume would be incomplete without 
reference = the exhaustive study by Schwager of the Carbonifer- 
ous Foraminifera of Chins. and Japan. ese form “ Fusulina 
t 
the former the old name of dina is retained, and the 
spheroidal ones are made to aise a new genus, for which the 
name Schwagerina is moapiet by Moller. These are illustrated 
by four plates and nearly a hundred pi dag many of which are 
highly magnified sections, which will be useful for co mparisons 
with Nummulites and with the bepeaunt “organic ee of 
Koz06n. NEWBER 
. Note on Professor R. D. Irving’s paper on rae Parcapenshis 
origin of the hornblende of the crystalline rocks of the North- 
f. \ 
western States; by . Wansworts. (Communicated.)— 
Since Professor Irving’s paper in the Jul number of this ie 
appears to impky that no one si r ichmann has ev 
studied microscopically the rocks of the Marquette district, sae 
no one except himself advocated fg: sees origin of the horn- 
blende in the “ greenstones,” or the eruptive origin ‘of the diabases, 
a ssa statement of the facts is cewae y. 
8s. KE. Wright published, in 1873, descriptions of the micro- 
acapio characters of a suite of Marquette rocks ;* while a more 
extended study by myself was published i in 1880.4 In my. work 
the secondar y origin of the hornblende in the “ greenstones” was 
distinetly advocated and the rocks classified prigi st o- ‘The 
olivine- -bearing character of part of the diabases was then first 
pointed out, and the supposed serpentine of Presque Isle was first 
ow 
e a peridotite of is lherzolite variety ; also the tra- 
chytic and rhyolitic nature of the Keweenaw felsites, since nis 
cated by Irving. The ae pene of the diabases as held by : 
vee genie oe and Whitney was also clearly proved by figures 
and see 
ince we agree on these points and since a copy of m my p 
lished paper was sent him at his special request, it is dificult 
to understand d why Professor Irving should ignore my work, and 
publish the same Views as original with himself. 
Cambridge, Mass,, July 10, 1883. 
a gt Sage of September 7, pe in Central America— 
A letter from Mr. A. Ernst, of Caraceas, in the July number of 
na Teueoad calls attention to an error in my last Notice of 
nerican Earthquakes (p. 357, ¥ 1883). He states that _ 
fay 
earthquake was not felt at een as stated y me. The st 
* Geol. Mich., 1873, ii, eariee ¢ Bull. Mus, Comp. Zool., 1880, vii, est 
FL e pp. 31, 3 39, 42, 46, 70, 
