306 Geological Society :— 
graphica,’ vol. iv. p. 72, pl. 13) as belonging to the naked Cepha- 
lopods, under the name of Paleoteuthis Dunensis (changed to Archeo- 
teuthis in the ‘ Leth. Geogn.’); and in the Jahrb. 1858, p. 55, Dr. 
IF’. Roemer described a second specimen from Wassennach on the 
Laacher See. Prof. Huxley reproduced, with remarks, Dr. Roemer’s 
description of the specimens; and, after observing that Mr. S. P. 
Woodward had already suggested (Manual of Mollusca, p. 417) 
that Roemer’s fossil was a fish, he stated his conviction that it was 
really a Pteraspis, agreeing in all essential particulars with the 
British Pteraspides, though possibly of a different species. 
3. ‘On the ‘ Chalk-rock ’ lying between the Lower and the Upper 
Chalk in Wilts, Berks, Oxon, Bucks, and Herts.” By W. Whitaker, 
Esq., B.A., F.G.S. 
The author has more particularly examined the band which he 
terms ‘“ Chalk-rock’’ on the northern side of the western part of the 
London Basin. Here it has its greatest thickness (12 feet) to the 
west, gradually thinning eastward. It is a hard chalk, dividing into 
blocks, by joints perpendicular to the bedding; and it contains hard 
calcareo-phosphatic nodules. It contains no flints; and in the di- 
strict referred to none occur below it; but there is often a band 
of them resting on its upper surface. It seems to form an exact 
boundary between the Upper and the Lower Chalk, being probably 
the topmost bed of the latter. In this case it will often serve as an 
index of the relative thickness of these divisions, or as a datum for 
the measurement of the extent of denudation that the Upper Chalk 
has suffered. North of Marlborough, where it is thick, the Chalk- 
rock appears to have given rise to two escarpments (an upper and a 
lower) to the western portion of the Chalk Range. 
Fossils are usually rare in this bed; but Mr. J. Evans, F.G.S., 
collected several from it near Boxmoor; and amongst them the 
genera Belosepia (hitherto known only as Tertiary), Baculites, Nau- 
tilus, Turrilites, Solarium, Inoceramus, Parasmilia, and Ventriculites 
are represented; and the following species have been identified— 
Litorina monilifera and a new species, Pleurotomaria sp., Myacites 
Mandibula, Spondylus latus, Sp. spinosus, Rhynchonella Mantelliana, 
Terebratula biplicata, and T. semiglobosa. 
February 6, 1861.—L. Horner, Esq., President, in the Chair. 
The followmg communication was read :— 
“On the Altered Rocks of the Western and Central Highlands.” 
By Sir R. I. Murchison, F.R.S., V.P.G.S., and A. Geikie, Esq., 
F.G.S. 
In the introduction it was shown that the object of this paper was : 
to prove that the classification which had been previously established — 
by one of the authors in the county of Sutherland was applicable, 
as he had inferred, to the whole of the Scottish Highlands.. The 
structure of the country from the borders of Sutherland down the | 
western part of Ross-shire was detailed, and illustrated by alarge map — 
oe eee eee ee ee oe 
