Dr. G. J. Hinde—Spitzbergen Chert-Deposits. 243 
Owing to a slight dip in the strata, these measurements are a little 
in excess of the true thickness, which is estimated at 876m. Making 
this allowance, this division consists of 111m. of siliceous schists and 
265m. or 870 feet of chert rock. The base of the division rests on 
the Spirifer limestone, whilst at its summit are the shales and marls 
of the Permian series, discovered for the first time by Nathorst and 
de Geer in 1882, the fossils in which, exclusively Permian in 
character, have lately been described by Prof. Lundgren.! The 
siliceous schists and cherts, therefore, known under the collective 
name of the Productus-chert division, constitute the summit of the 
Permo-Carboniferous series in Spitzbergen. 
Most of the specimens of cherty rock forwarded to me by Dr. 
Nathorst are from the Productus-chert beds exposed on the eastern 
coast of Icefjord at Tempelberg and at Green Harbour and from 
Axel’s Island in Bell Sound. The following are the salient characters 
of the principal specimens. 
1. Specimens of white cherty rock at Templeberg, from near 
the summit of the Productus-chert and probably upon the same 
horizon at Angelinsberg, or Lovénsberg, in Hinlopen Strait. The 
rock is compact, of a greyish or milky-white tint, hard enough 
to scratch glass, and it gives in places slight ebullition with acid. 
The Tempelberg specimens contain some grains of glauconite and 
quartz, but these are not present in the Hinlopen Strait example. 
The specimens also contain numerous shells and casts of Productus, 
and possibly also of Spirifer, the shells still retaining in part their 
normal structure of carbonate of lime. The matrix of the rock (if so 
it may be termed) in which these shells are imbedded, and of which 
their casts are composed, is a mass of closely-packed sponge spicules, 
chiefly linear or rod-shaped, either lying parallel to each other, or 
more frequently crossing one another irregularly (Pl. VIII. Fig. 8). 
These spicules are of chalcedonic silica ; in microscopic sections by 
transmitted light they show an outer ring of a brownish yellow 
tint, whilst the central or axial portion is either of transparent silica, 
or of an opaque material. In some parts of the Hinlopen specimen 
the spicules gradually pass into a, nearly pure translucent chert, in 
which their forms have, for the most part, disappeared, and only the 
solid casts of their axial canals can be distinguished. 
The spicules in these rock-specimens are generally imperfect and 
fragmentary ; the only recognizable forms are small curved cylinders 
with slightly inflated extremities (Pl. VIII. Fig. 9), similar to those of 
Reniera clavata, Hinde, which are very common in the cherty sponge 
beds of the Yoredale Series of Yorkshire and North Wales (Brit. Pal. 
Sponges, pt. ii. p. 148, pl. ix. figs. 5 a, b, Pal. Soc. vol. for 1887). 
Most of the detached spicules are apparently simple monaxial forms, 
and may perhaps belong to monactinellid sponges. Dr. Nathorst 
informs me that the bed of white chert at Tempelberg is only about 
three feet in thickness, but that further to the north-east it gradually 
1 Anmarkningar om Permfossil fran Spetsbergen; Bihang till K. Svenska Vet. 
Akad. Handb. Bd. 18, Afd. iv. No. 1, pp. 1-26 (1887). Gf. Gzoz. Mac. March, 
1888, p. 181. 
