THE 
GEOLOGICAL MAGAZINE. 
No. XVII.—NOVEMBER 1865. 
ORIGINAL ARTICLES. 
Se 
J. Nore on THE PAL@onTOLOGY OF THE RuzTIC (PENARTH*) 
Beps in WESTERN AND CENTRAL SOMERSET. 
By W. Boyp Dawxtns, M.A., Oxon., F.G.S., of the Geological Survey of Great 
Britain. 
ee BRIEF notice of some of the more important Rhetic Fossils in 
the district described in this Magazine (vol. i. p. 257) may 
perhaps be some guide to the identification of the beds in other Bri- 
tish localities. 
Of the more common and characteristic forms, Pecten Valoniensis 
and Sargodon tomicus were derived from the same layer as that 
which yielded a tooth of Hypsiprymnopsis Rheticus below the bone- 
bed. The former comprises two bands of limestone in the upper por- 
tion of the Avicula Contorta series, or middle member, at Watchet 
and Uphill. My colleagues, Messrs. Etheridge and Bristow. have 
also found it to occupy the same horizon at Penarth. The chisel- 
shaped teeth of the latter in the unworn state, having their cutting 
edge traversed by a notch, were probably the anterior incisiform 
teeth of a fish allied to Sargus. Teeth of Acrodus minimus are 
enormously abundant in the Middle Rhetic series. Pleuro- 
phorus angulatus is also very abundant in the same horizon 
and forms a layer of ‘Pleurophorus’ limestone. (See Quart. Journ. 
Geol. Soe. vol. xx. p. 396.) Avicula contorta is restricted to the 
Middle Rhetie division, while Ostrea interstriata is common both to 
the middle and upper divisions ; and Cardium Rheticum is found 
throughout. ‘These last three species are figured in the plates accom- 
* Since the paper published in the Guorocican Macazinn (Vol. L, p. 257) was 
written, Sir Roderick Murchison, F.R.S., Mr. Bristow, F.R.S., and Mr. Etheridge, 
F.G.S., on an examination of the beds therein described, and also of the corre- 
sponding strata in South Wales, have determined upon naming them the Penarth 
series, from their great development at that place, and from the desirability of 
having a British name for a series of rocks well represented in the British Isles, 
and shown by a distinct colour on the Map of the Geological Survey.—[See British 
Association Reports in Gzotocican Magazine, Vol. I, p. 236.] 
VOL. II.—NO. XVII. Atal 
