1865.] TAWNET RH^TTC BEDS A-^T) SFTTON STONE. 71 



Since commencing this paper, a pit sunk for sand on Stormy Down 

 revealed the following section (this excavation has since been again 

 partly filled up ) : — At the base were seen 6 feet of the pale-green 

 and white sandstones ; these were extremely fossiliferous (a speci- 

 men from these beds is presented to the Society) : above were green 

 laminated marls containing Avicula contorta, and then yellow sands 

 and sandstones (about 6 feet). 



3. Bridgend district. — Though fossils were perfectly conclusive as 

 to the true nature of the above beds, yet the following section is of 

 great interest as showing their relation to the Rhoetic shales and bone- 

 bed. This section is on the south side of the South Wales Railway- 

 cutting at Cwrt-y-Coleman, about a mile and a half west of Bridgend. 



At the base are seen 8 or 10 feet of white or yellowish massive 

 sandstone with a few small rounded quartz pebbles. I have not 

 found fossils in this bed, except coprolites at the top of it, but 

 I believe it may be of Ehsetic age ; and it is probable that it will be 

 found to be fossiliferous, as it contains brown stains and marks of 

 organic matter, and in this and general structure is like some of 

 the beds at the top of the section. It may probably be of these 

 sandstones that Sir H. De la Beche notices travelled blocks on the 

 western part of ISTewton Down * ; he describes it as a quartz rock 

 (between Pyle and Bridgend), with the grains of white quartz firmly 

 bound together by nearly colourless silica. 



Above this are about 3 feet of shales, including a curious marly 

 limestone, grey and green in colour, the grey part of which is very 

 full of shells and sheU-fragments : the fracture of this bed is con- 

 ehoidal, so that the shells are nearly always broken across. Above 

 this is a siliceo- micaceous limestone from 2 to 3 inches thick, with 

 irregular marly surfaces : this is the true representative of the Aust 

 bone-bed. On splitting off the exterior laminae of this bed a multi- 

 tude of teeth of Acrodus and Hyhodus and fish-scales are seen. I 

 have also found a reptilian bone. The remains I have noticed in 

 this bed are 



Saurichthys apicaUs, Gyrolepis tenui- 



acuminatus, striatus, 



Acrodus minimus, alberti, 



acutus, Hybodus minor {Ag.), 



This bed is not conglomeratic, beyond an occasional rolled quartz 

 pebble, but is a fine-grained tough micaceous limestone. 



I was ignorant at the time of this discovery that the bone-bed had 

 been found so far west as St. Hilary, nine miles east of Bridgend. 



Above the bone-bed come dark shales, 3 feet; then a chocolate- 

 coloured soft sandstone-bed (1 inch) containing Avicula contorta, Pec- 

 ten Valoniensis ; then shales, 3 inches ; then three beds of siliceous 

 limestones with fish-scales, Anomia, &c.; these beds change their 

 conditions somewhat at different parts of the section, being more 

 sandy in places or again thin out into shale ; above are 9 feet of 

 shales, marls, and sandstones ; and then 17 feet of white and pale- 

 green and yellow sandstones and sands. 



* Loc. cit. p. 252. 



g2 



Hybodus cuspidatus {Ag?), 



orthoconus (Plien.), 



plicatilis (Ag.), 



and scales of other species. 



