6 MR. L. RICHARDSON" ON THE RH^TIC OF [Feb. 19U,: 



Roughly speaking, the Westbufy Beds can be separated into 

 two parts, an upper and a lower, according to the occurrence of 

 vertebrate and invertebrate remains respectively, for vertebrate 

 remains abound in the beds from the horizon of Bed 15 (that is, 

 the main Bone-Bed or its equivalent) downwards ; while inver- 

 tebrate remains predominate in that portion of the Westbury Beds 

 which lies above Bed 15. 



Beds containing an abundance of vertebrate remains occur at 

 several horizons in the Westbury Beds ; but one stratum, that 

 which I have numbered 15 in my various sections, I regard as 

 a contemporaneous deposit. Ceratodus teeth are abundant in it 

 at Aust Cliff; they have also been recorded from the equivalent 

 stratum at Garden Cliff, near Gloucester, and at Blue Anchor Point 

 in West Somerset. Indeed, the teeth of this fish might almost be 

 looked upon as zonal fossils. 



At Aust Cliff the Bone-Bed (15) rests directly upon the 

 Tea-green Marls, and contains rounded lumps of that subjacent 

 rock. But at Blue Anchor it is separated therefrom by 22 feet of 

 Westbury Beds, 14 feet or so of Sully Beds, and about 80 feet of 

 Grey Marls. 



The deposits that belong to the Westbury Beds and occur below 

 Bed 15 in the Watchet district include a number of nodular lime- 

 stones with a most interesting series of invertebrate fossils — 

 among them being excellently-preserved specimens of Pteromya 

 crowcombeia Moore, and other rarities. 



The sections near Watchet have long been known to be more 

 than usually rich in fossils, the comparative scarcity of which,, 

 if not their absence elsewhere, was a matter for investigation. 

 Now, however, it will be seen that there is a series of beds below 

 Bed 15, ' infra-Bone-Bed deposits ' they may be called, in the- 

 Watchet district, which is not equalled elsewhere in the country. 



North of Aust, at Garden Cliff, infra-Bone-Bed deposits are again 

 in evidence ; but their geographical distribution to the north, as 

 shown by sections along their outcrop, is not extensive, and was 

 probably governed by earth-movements anterior in date to their 

 time of deposition. 



As regards the Westbury Beds above Bed 15, the following- 

 points should be noticed : — 



(1) The Pleurophorus Bed is a useful horizon, is frequently of bone-bed' 



nature, in West Somerset is crowded with gastropods, and is probabiy- 

 the bed that, at Beer Crocombe, Moore called the ' Flinty Bed ' ; 



(2) Between the maxima of Pteria contorta and Chlamys valoniensis there is ; 



generally a rather barren deposit of shale ; 



(3) The horizon of the maximum of Chlamys valoniensis is generally marked 



by one or more limestone-beds ; 



(4) Somewhere about a foot below Bed 7 is the niveau of the ophiuroid 



O'phioleipis damesi; 



(5) The Cardium-cloacinum Bed is well characterized by Cardium cloacinum 



Qu., and affords an excellent datum-level for correlating sections on 

 the Bristol-Channel littoral. 



