332 Scientific Intelligence. 
pores sere cavities was the moisture which altered the pyroxene 
r other minerals of the rock to chlorite, and made the zeolites 
and quartz out of chiefly its me iain and that this kind of trans- 
ponies of the igneous rock all cavities or fissures into 
Ww 
times a cupriferous amygdaloid ; and that simultaneously it was 
carried also to some extent into the adjoining sandstone. But all 
the conditions of the process are not yet explainable, and, there- 
fore, while differing widely from a egies on this and other 
points in his Waser I agree with in this, th at “until we 
on the occurrence of Productus giganteus from an argillaceous rock 
of Carboniferous age in the valley of McCloud River, Shasta Co. 
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species of Dicictlondéava, S. Salteri Billings, S. Davidoons Billings, 
in the town of Ringgold, Catoosa Co., Georgia, where they were 
collected by Lieut. A. W. Vogdes, U.S. ‘A. With regard to the last 
he says that the ath si 8 of this collection were doubtless cor- 
rectly referred by Lieut. Vogdes (in this Journal, Dec. 1879, xviii, 
475, 477), tothe Clinton Group of New York; and their discovery 
in Georgia, if the identification is correct, “has special interest 
because ~~ Je te have hitherto been found only in strata 
of the island of Anticosti, and also because these (with the asso- 
ciated fossils) indicate the cceniean of the Georgia, Clinton, and 
Anticosti strata in America, and the Upper Llandovery of Great 
Britain. Profess ssor White also states that the Discina-like Brachio- 
pod from the Primordial strata at Antelope Spring, Southern Utah, 
which he has described under the name of Acrotreta subsidua, “ re- 
ferring it to that genus provisionally,” belongs to Linnarsson'’s 
new genus Acrothele; and he adds that it is not unlikely that 
ome oreowege species referred to Discina will be found to belong 
* this gen 
tei as White has also 180 pages of ne 9 et of fossils, and 
32 plates, in the Twe Ifth Annual Report of the U. 5. Geo ological 
‘“author’s edition” in Jul last. The species ny eee are from 
the manent Ac Laramie, sds i Jurassic, Triassic, and Carbon- 
iferous grou The ort is a continuation of his Contributions 
to as ccteueats Paleontcldgy 3 in the Report for 1877. 
