62 



BONE-BED, ETC. 



Upper 

 Gallesy. 



Wall-case 41. 



Egerton, in consequence of the presence of certain genera of 

 fish. Mr. Strickland, and most other geologists considered 

 them to be Lias. They may be, probably, the attenuated 

 representatives of the Koessen beds of the Austrian Alps. 

 (For a condensed account of these, see Supplement to the 

 5th edition of LyelFs " Elements of Geology," p. 26), 



A. C. R. 



172. — Upper Silurian bone-bed (top of the Upper 

 Ludlow rocks) containing bones, coprolites, &c. — Ludlow 

 Salop. 



173 — Oyster bed, from the middle Purbeck ; locall 

 termed " cinder" 



This bed, which is well displayed in Durlston Bay, is a 

 mass of oysters, (ostrea distorta,) twelve feet thick, asso- 

 ciated with Trigonia, Cardium, and other shells. It is 

 purely a marine formation. In this bed, the late Professor 

 Edward Forbes found, for the first time, the Echinoderm, 

 called by him Hemicidaris Purbeckensis. (See Vertical 



y 



Sections No. 22, and Map No. 16. 



174. — Coral rag, with double burrows of sand worms 



{Arenicola), &c. — Between Dairy House, and Abbotsbury 



Castle, Dorset. 



175. — Part of a consolidated recent beach now in pro- 



*■ 



cess of formation. Red Wharf Bay, Anglesea. — Presented 

 by Mr. G. Niblet. The consolidation is a result of the 

 percolation of carbonated water, which disolves part of the 

 lime of the shells, and evaporating, re -deposits it among the 

 fragments of stone and shell, thus cementing them together. 



A. C. R. 



176. — Lower Llandovery rock, with peculiar surface 

 marks. — Aberystivith, Cardiganshire. 



177. — Carboniferous limestone, bored by marine 

 animals (Lithodomus). — Murdercombe Bottom, near Frome, 

 Somerset. (See " Memoirs of Geological Survey," vol. i., 



p. 291.) 



Over a great portion of the district from which the speci- 

 men is taken, the Inferior Oolite rests unconformably on 



! 



tan ibovi 



u 



n 



er 



(See Verti 

 ' 1 79— P 



mar 



?4 Si 



on soft itn 



i, In 

 fled after 



sometimes 



»*, and 



S when 



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