Geology and Mineralogy. 237 
language as Emmons himself would have used.” It is with great 
satisfaction that I am able to make the correction and cite, from 
the same letter, the fact that “there i is nothing in the Repo ort any- 
where favorable to Taconism,” although, as he also writes, it does 
not refer the system distinctl to the Lower Silurian, except in 
view. Qn the earlier pages, 251 to 257, Professor Edwa rd 
and ee tacd to Professor James Hall, just before mpl 
tion of the Report, it was Mr. Hall’s opinion that the quartzyte 
was the Medina sandstone and that the Taconic group was 
t 
of the fossils—none of them very distinct specimens—to the 
Upper Silurian. 
Professor Hitchcock also says, in Bc recent vig to me, after 
remarking on his disbelief in “Taconism :” “ Within the past two 
years I have gone over most of the Vermont sections, and have 
felt that they demonstrated the essential equivalence of the 
Taconic gangs with the Potsdam and ha! ink os lime He ones 
This important correction was Pho received until after my 
article on the age of the Green Mountains (p. 191) was printed, 
i . DANA, 
or else this note would have been attache i J 
pein ie of the Silurian Fossils of the Girvan Dis- 
; with special reference to those contained in 
the “ Gry Collection,” by H. Atteynz Nicaorson and Roperr 
Erurrip E, Jr. Fasciculus II. oe Sua Phyllopoda, Cirripedia, 
and Ostracoda, pp. 137-233, with pes x-xv. Edinburgh and 
eed Win. Blackwood & 
(at and its Alterations a, from the granite veins 
palate County, Massachuse A. A, Jutren has 
rack recently (Annals N, Y. Regt o aoa bet kWh alua- 
ext ape | memoir on spodumene and the results of its 
alterations The two localities which are particularly described 
are those of Goshen and Chesterfield, Massachusetts. Analyses 
of pure and unaltered spodumene from these localities yielded the 
results gies below. No. 1 was from the Levi Barrus farm in 
SiO, Al,0; Fe,0; MnO MgO CaO Li,O Na,O K,0 H,0 
I 63°27 93-73 117 0-64 2°02 O11 6°89 0°99 145 0°36 = 100°63 
8 6186 23-43 104 1°55 O79 699 0°50 1°33 0°46 = 100°68 
These sepa agreeing analyses correspond very nearly to the for- 
Mula Li, Al i,0,,, for which the quantivalent (= ye ygen) ratio 
Am. Jour. Scr. Cpeses Srrres, Vor. XIX, No. 111.—Marcu, 
17 
