246 Dr. G. J. Hinde —Spitzbergen Chert-Deposits. 
organic origin of the chert, or flint as it is termed, is not even sus- 
pected, but it is supposed to have an undefined relation to igneous’ 
rocks. But in the section measured by Geer on Axel’s Island the 
chert and siliceous schists form an uninterrupted series of strata, 
376 meétres in thickness, without volcanic materials, nor do such 
occur in the Permian strata overlying them. 
The fact is not without significance that the geological horizon on 
which this enormous series of cherty rocks in Spitzbergen occurs 
corresponds approximately with that in which rocks of a similar 
character are so largely developed in the British Isles. The Car- 
boniferous chert beds in Britain mainly appear in the upper portion 
of the marine Carboniferous series, between the true Mountain Lime- 
stone and the Millstone Grit. In Spitzbergen, also, they form the 
upper portion of a series of rocks regarded stratigraphically as the 
equivalents of the Carboniferous Limestone, even though they contain 
a certain admixture of Permian fossils. In Spitzbergen, however, 
the grits, sandstones, and coal-bearing beds, which succeed the Yore- 
dale rocks in this country, are not represented, and the Permo- 
Carboniferous cherts are directly followed by shales, marls, and 
sandstones, containing an exclusively Permian Fauna. 
II. On the Fossil Sponges from Spitzbergen described by Dr. E. 
von Dunikowski. 
The cherty rocks of Spitzbergen, unlike those of Yorkshire and 
North Wales, have yielded entire forms of sponges, in addition to 
the detached spicules thickly scattered through the rock itself. These 
sponges were discovered by the last Swedish Expedition under 
Nathorst and de Geer, most of them in the dark siliceous schists of 
the Productus-chert series of Axel’s Island ; some were also obtained 
from the Cyathophyllum limestone of Templeberg and Gypshook, and 
from the marine beds of the Ursa sandstone at Middlehook in Bell 
Sound. The specimens were entrusted to Dr. E. von Dunikowski 
for description, who prepared microscopic sections from them, and 
described them as a new genus of monactinellid sponges under the 
name of Pemmatites, including within it the following species: P. 
verrucosus, P. arcticus, and its two varieties, macropora and latituba. 
The characters assigned to the genus appeared to me so peculiar, 
that at my request Prof. Lindstrém kindly forwarded to me most 
of the type-specimens, and the microscopic sections from them, for 
examination. as well as an additional specimen of P. arcticus, vay. 
macropora, which had not been submitted to Dr. Dunikowski, from 
which, and from another specimen, I have had further microscopical 
sections prepared. As the results of my study of these type-speci- 
mens I have arrived at conclusions as to their characters so widely 
1 A somewhat similar origin was attributed to a band of flinty or horny rock in the 
Carboniferous Limestone of Glencart, Lalry, Ayrshire, by my friend Mr. John Young, 
F.G.8., who regarded the silica as deposited chemically by heated waters from springs ‘ 
connected with volcanic vents in the neighbourhood (Proc. Nat. Hist. Soc. Glasgow, 
April 25. 1882, p. 237). Since hearing my paper on the organic origin of the Irish 
Carboniferous chert, Mr. Young examined sections of this flinty band under the 
microscope, and he has informed me that it is crowded with minute sponge-spicules, so 
that no doubt of its origin from these organisms can be entertained. 
