238 Reports and Proceedings : 
middle part was shown to be a mass of black paper-shales containing 
Avicula contorta, a shell eminently characteristic of the formation, 
and thin beds of a tough bluish-grey limestone, coarsely fissile, and 
containing great numbers of another characteristic shell, Pecten 
Valoniensis, as well as Cardium Rheticum, &c. These black paper- 
shales, with their thin included bands of even-bedded, tough, blue- 
erey, fossiliferous limestone, are well shown in the railway-cuttings 
at Patchway, opposite to and on either side of the Station. It is 
towards the lower part of these paper-shales that the bed so well 
known to collectors by the name of the ‘Aust Bone-bed’ is met with 
at Aust Passage, at Garden-Cliff near Westbury-on-Severn, at 
Penarth, and-in other localities in the West of England. In those 
localities, as well as at the Patchway Cutting of the South-Wales 
Union Railway, this curious bed contains immense numbers of the 
bones, teeth, and scales of Fishes and Saurians, together with their 
fossil excrement (coprolites)—becoming in places a true bone-breccia, 
and very commonly highly pyritiferous. 
The lower portion of the Rheetic strata consists of alternations of 
hard and soft marls, passing gradually into the red and green marls 
of the Keuper formation, upon which they are based. 
The junction with the overlying Lias is of a more decided nature, 
and is denoted by the presence of Ostrea liassica, Modiola minima, 
and Ammonites planorbis in the lowest Lias; the two former shells 
being especially abundant and well preserved at Penarth, and the 
last in the shales at Watchet. 
The upper subdivision of the Rheatic beds consists, for the most 
part, of alternations of limestones, marls, and clays, and includes 
certain beds which are commonly known as ‘ White Lias,’ from the 
occurrence amongst them of a smooth-grained compact limestone 
(resembling the lithographic limestone of Solenhofen in texture and 
general appearance), to which the name ‘White Lias’ is usually 
given by some of the quarrymen of the West of England. The well- 
known ‘Cotham marble,’ cr ‘Landscape-stone’ of the dealers in 
polished rocks at Bristol, is almost universally met with in the lower 
part of the White Lias series of the neighbourhood of Bristol, and 
in Dorsetshire; and thus affords an easily recognized horizon of 
great value in defining the upper boundary of the Rheetic series. 
In conclusion, Mr. Bristow directed attention to the circumstance, 
that, it being desirable that a name borrowed from a British locality 
should be used on the Map of the Geological Survey to denote the 
theetic Beds, he was induced to recommend, at the suggestion of the 
Director-General, that the term ‘Penarth Beds’ should be adopted 
for that purpose. ‘That name was selected by Sir Roderick Murchi- 
son, partly because none of the other places where sections of the 
beds under notice are displayed are of sufficient importance in them- 
selves, or afford names sufficiently distinctive for the purpose in view; 
but chiefly because the docks and other great works now in course 
of construction by the Marquis of Bute, and the vast numbers of 
ships which make use of the Penarth Roads, confer additional im- 
portance on a locality where the beds are highly developed and well 
