﻿392 ME. L. EICHAEDSON ON THE EH^TIC AND [Aug. I905, 



similar nature at Garden Cliff, Westbury-on-Severn. At Garden 

 Cliff, 16 inches above the basal bone-bed is the ' Lower Pullastra- 

 Sandstone.' At Lavernock, 18 inches above the presumed equiva- 

 lent deposit, is a thin layer composed of hundreds of teeth of 

 Acrodus minimus and scales of Gyrolepis Alberti. At Garden Cliff 

 a deposit of shale, 2 feet thick, separates the Lower from the Upper 

 jPitZ/a^ra-Sandstone ; at Lavernock the deposit intervening between 

 the beds that may be regarded as the equivalents of the sandstones 

 measures only 13 inches. Bed 17 is also a 'bone-bed,' and frequently 

 contains vertebrse of Plesiosaurus. Black shales with a grey lime- 

 stone-band separate this bed from a series of sandstone-layers 

 with shale-partings, and frequently full of fish-remains, usually 

 comminuted. If the correlation of the Bhsetic deposits (20 to 16) 

 enumerated above be correct, then the next bed in ascending order 

 should be the equivalent of the Bone-Bed (15) of Garden Cliff. This 

 was thought to be the case by Etheridge, and it certainly seems 

 probable. John Storrie wrote : — 



' The bone-bed proper ... is a continuous bed through the whole [Penarth- 

 Lavernock] section, and is described by Etheridge as " a dark-grey grit, or hard 

 indurated pyritic limestone, 2 or 3 inches thick (oftener about 1 inch), made up 

 of minutely-comminuted fragments offish-teeth, scales, and bones." This bed 

 ... is accessible in the whole Penarth section, and is always constant in 

 character, except at Lavernock, where it is more pyritized than elsewhere. 

 This bed very rarely contains large bones or spines ; on one occasion only have 

 I found such.' 1 



The most persistent strata in the Pteria ( Avieula) -contorta Zone are 

 the Pecten-Beds (7 & 5 b), especially the lower of the two. At 

 Lavernock, they can be easily traced across the foreshore. Bristow 

 observed that the lower bed was full of Pecten (Ghlamys) valoniensis ; 

 but, according to my investigations, it was of rather rare occurrence 

 in the actual limestone, and in neither of the Pecten-Heds did I find 

 lamellibranchs to be abundant, as is usually the case. However, the 

 Black Shales, for 2 or 3 inches below Bed 5 b, are extremely fossili- 

 ferous, containing Pecten (Ghlamys) valoniensis, Pteria (Avieula) 

 contorta, 2 scales of Gyrolepis Alberti, and coprolites (of fishes chiefly). 

 In places immediately below this shale is a thin earthy limestone- 

 layer with a layer of ' beef on the under surface. At 5 inches 

 below 5 b is a seam full of Pteria (Avieula) contorta ; and in the shales 

 below that again, numerous examples of Pecten ( Ghlamys) valoniensis, 

 and Schizodus Ewaldi, Gervillia prcecursor, Protocardium Phili>ppi- 

 anum, Orbiculoidea Toivnshendi, Pleuromya (?), Placunopsis alpina 

 (small and large forms), scales of Gyrolepis Alberti, teeth of Acrodus 

 minimus (rare) and Saurichthys acuminatus, and coprolites. The 

 vertebrate-remains occur mostly in a thin layer at 8 inches below 5b. 

 This is certainly the most fossiliferous horizon in the Rhsetic at this 

 locality ; and fortunately the deposit is easy to investigate. Black 



1 Trans. Cardiff Nat. Soc. vol. xiv (1882-83) p. 100. 



2 Tteria, Scopoli, = Avieula, Brug. I am at pi*esent engaged in the revision 

 of the representatives of the Pteriidas from the Puhsetic, Liassic, and Inferior- 

 Oolite rocks ; and also those of the Mytilidse from the same rocks. 



