244 Dr, G. J. Hinde—Spitzbergen Ohert-Deposits. 
increases in thickness. The thickness of the white chert bed in 
Hinlopen Strait is not known. No corresponding bed of white 
chert occurs in the section at Axel’s Island. 
2. Specimen of bluish chert from Bell Sound, probably from 
Axel’s Island. This is a hard, brittle rock, with a splintery fracture ; 
it gives no action with acid. It contains the mould of a large 
Brachiopod. The surface in places is covered with the impressions 
of slender elongated spicules, but in the interior of the specimen 
only the axial portions of the spicules remain. This specimen is 
precisely similar in appearance and character to the cherty rocks 
of the Yoredale Series in Yorkshire, and could not be distinguished 
from them. 
3. Specimen from the Productus-chert at Green Harbour, Icefjord. 
This is a dark, siliceous rock, with Producti, Polyzoa, and probably 
small Corals. The cells of these organisms have been infilled with 
siliceous material, and their walls have been weathered away on the 
surface; the Productus shells are, in part, replaced by silica. No 
spicules can be determined on the outer surface of the rock, but they 
can be seen in a thin section. Amongst the monactinellid spicules 
there is a cruciform spicule belonging to a hexactinellid sponge 
(PL. VIII. Fig. 15). 
4. Specimen from the Productus-chert from South Axel’s Island. 
This is a hard, dark, siliceous schist, containing fragments of the 
problematical fossils known as Taonurus or Spirophyton. It appears 
mainly to consist of very minute subangular quartz grains in a dark 
cement. There are scattered in the rock numerous minute cylindrical 
spicules, similar to those of Reniera bacillum, Hinde, from the Yoredale 
Series of Yorkshire and North Wales (P]. VIII. Fig. 10). Frequently 
the spicules occur as hollow casts or partially replaced by iron rust. 
do. Specimens of dark siliceous schists from the Productus-chert 
division of South Axel’s Island and Middle Hook in Bell Sound. 
These rocks, like the preceding, are mostly made up of minute sub- 
angular grains of quartz and a varying amount of calcite. Thin 
sections show a few spicules in places, but they are insufficient to 
affect the character of the rock. 
6. Nodular masses of chert intermingled with crystalline calcite 
from Cape Wijh. The chert in these specimens is nearly translucent, 
and shows but little structure. It contains traces of spicules and 
Foraminifera. 
7. Dr. Nathorst has also forwarded to me a smooth rounded 
pebble of chert, from the gravels of Nordenskidld’s Berg, which are 
of Tertiary age, with the view of ascertaining if its minute structure 
corresponded with that of flints from the Chalk, which, in outward 
appearance, it much resembles. A microscopic section of the pebble 
showed that it was composed of chalcedony and crystalline silica, 
and that it is filled with the remains of spicules which are now for 
the most part only represented by the infilled casts of their axial 
canals ; in some instances, however, the spicules consist of an opaque 
material. They are chiefly fragments of rod-shaped forms, but 
amongst them are fusiform, acerate, and also lithistid spicules, closely 
