: 
ORIGIN OF CRYSTALLINE ROCKS. 503 
crinoidal stems and plates in a paleozoic limestone from New 
Brunswick, which is made up of organic remains. This silicate 
which, in decalcified specimens, shows in a beautiful manner the 
intimate structure of these ancient ser I have found by analy- 
sis to be a hydrous silicate of alumina and ferrous oxyd, with 
magnesia and alkalies, closely related to fahlunite and to joll 
The microscopic examinations of Dr. Dawson show that this sil- 
icate injected the pores of the crinoidal remains and some of the 
interstices of the /associated shell-fragments, before the introduc- 
tion of the calcite which cements the mass. I have since found a 
silicate almost identical with this, occurring under similar condi- 
tions in an Upper Silurian limestone said to be from Llangedoc in 
Wales. 
Gümbel, meanwhile, in the essay on the Laurentian rocks of Ba- 
varia, in 1866, already referred to; fully recognized the truth of 
the views which I had put forward, both with regard to mineralogy 
of Eozoön and to the origin of the crystalline schists. His results 
are still farther detailed in his Geognost. Beschreibung des östbayeris- 
ches Grenzegebirges, 1868, p. 833. Credner, moreover, as he tells 
us,ł had already from his mineralogical and lithological studies, 
been led to admit my views as to the original formation of serpen- 
tine, pyroxene and similar silicates (which he cites from my paper 
of 1865, above referred tot), when he found that Gümbel had ar- 
rived at similar conclusions. The views of the latter, as cited by 
Credner from the work just referred to, are in substance as fol- 
lows :— The crystalline schists, with their interstratified layers, 
have all the characters of altered sedimentary deposits, and from 
their mode of occurrence cannot be of igneous origin, nor the result 
of epigenic action. The originally formed sediments are conceived 
to have been amorphous, and under moderate heat and pressure to 
have arranged themselves, and crystallized, generating various 
mineral species in their midst by a change, which, to distinguish it 
from metamorphism by an TE process, Gümbel happily des- 
ignates diagenesis. 
It is unnecessary to remark, that these views, the conclusions 
from the recent studies of Gümbel in Germany and Credner in 
orth America, are identical with those put forth by me in 1860. 
* Amer. Jour. tile TH, i, via 
_ t Hermann Credner; die d i F i Nord Amer- 
Halle 1869. į pian in the Quar. . Geol. Jour., XXI, 67. 
