466 PKOCEEDINGS OF THE GEOLOGICAL SOCIETY. 



on the same horizon at Keinton Mandeville, four miles to the north- 

 west. Next to the interest attaching to insect-life in these beds 

 is the wonderful number of its Crustacea. I lately found on the 

 railway at Pyle Hill, near Bristol, a block of stone which had come 

 down from the top of that cutting; and, although only a foot 

 square, it contained a colony of fifteen specimens, which my friend 

 Mr. Woodward (see Geol. Journ. vol. xxii. p. 498) thinks belong to 

 Eryon Wihncotensis. At Wilmcote, near Stratford-on-Avon, this 

 species comes from the " Bottom Block Bed " of the Lower Lias ; 

 at Pyle Hill also, from one of the basement beds*, and again at 

 Camel it is found under similar circumstances, and apparently in as 

 great abundance, as several specimens are to be observed in the same 

 block. The persistency of similar conditions over so wide an area is 

 of much interest. The quarrymen informed me that they had found 

 vertebree of either Plesiosaurus or Ichthyosaurus in these beds ; but 

 none came under my notice. 



The beds 88 and 90 are called " Hat and Cap " by the quarrymen. 

 Occasionally they contain concretions ; and when these occur, the thin 

 laminae of the beds accommodate themselves to them, and often pass 

 up in conical peaks to the upper surface of the superimposed limestone. 

 When quarried, these flake oif and form a rude " hat or cap," with 

 which the boys occasionally adorn themselves. 



The true passage from the Ehsetic beds into the Lower Lias is 

 through these beds ; and wherever they are absent, to that extent 

 there will be unconformability. 



d. The Saurian and Ostrea Beds, — The " Firestones^- — The next 

 noticeable series of beds in the Camel-Hill section are the " Fire- 

 stones," which are all composed of a dense coarse-grained blue hme- 

 stone, lying very closely one upon another. These were included in 

 my Beer Crowcombe sections under the " Saurian Zone," from the 

 fact that they are the chief depository of the numerous Plesiosauri 

 and Ichthyosauri of this period. It is from the " Firestones " that all 

 the best paving-stones come, and they yield blocks of considerable 

 superficial area. These limestones are worked at intervals in the 

 south-west of England over hundreds of square miles, and, as pre- 

 viously shown by myself, they are found to be generally uniform in 

 thickness over very wide districts, and the separate beds are often 

 disting-uished by the same names. From certain conditions, possibly 

 their deposition in a shallower sea, or their encroachment on ancient 

 coast-lines, the saurian contents of these beds may not continue. 

 This is the case with their equivalents in South Wales, although in 

 the district under notice, and in Gloucestershire and Warwickshire, 

 the presence of saurians is so constant. In their absence this horizon 

 is then to be recognized by the wonderful profusion of the Ostrea 

 liassica, which in many instances literally cover the surfaces of the 

 beds. This shell is also an abundant one in the " White Lias " 

 below, and passes far upwards, although it occurs more sparingly in 

 the higher members. 



* The exact position of this bed will be seen on reference to the Bedminster 

 section. 



