500 



PROCEEDINGS OP THE GEOLOGICAL SOCIETY. 



able to fix it as the horizon of the large Discina Toiunshendi, David- 

 sou, of which I secured two spccimeus. 



No separate bone-bed occurred in this section. Ehsetic bones and 

 teeth were either distributed throughout the strata or were found 

 washed into any little depressions in them. 



In most of the sections to which reference has been made within 

 the coal-basin, the lower beds of the Lias, included in the zones of 

 the Insect-limestones, the Ostrea-beds, and the still higher ones of 

 Aynmonites planorhis and Ammonites angidatus as a distinct horizon, 

 are wanting ; and every^vhere the Ammonites- BucTclandi beds, mth 

 Ammonites angulatus associated, repose immediately on the Rhsetic 

 "White Lias. 



One of the most important zoological features incident upon the 

 very thinly represented and unconformable conditions of the Lias 

 within the coal-basin is the paucity of Saurian remains within the 

 area; and the same observation applies to the Liassic beds in con- 

 nexion with the South Wales Carboniferous Limestones. In no part 

 of the latter district have I yet found a single Saurian bone ; and 

 their absence south of Bath is most marked, notwithstanding that 

 at Lyme and other localities they are so abundant in the Ammo- 

 nites-Buclclandi beds. They appear more plentiful from Bath to 

 the western edge of the coal-basin, but even there are usually met 

 with only as scattered bones ; and I have no hesitation in saying 

 that, outside the coal-basin, more reptilian remains would be found 

 in one year in a single quarry than in all the Liassic workings put 

 together within the basin south of Bath. 



4. Sections near Bristol. — The quarries of Bedminster Down are at 

 the western edge of the Somersetshire coal-basin ; and it is interest- 

 ing to observe that with them we have a return to the ordinary con- 

 ditions, and to the succession from the Keuper Marls upwards, of 

 the lower typical beds of Camel and Beer, although they are not so 

 thickly represented. 



Section at Bedminster 



Bhcetic White Lias. ft. in. 



1. Thin layers of hgiit-bhie 



stone and marl, ex- 

 posed 2 



2. EubblyWhite Lias, with 



very numerous shells 2 



3. Marl 2 



4. White Lias 2 



5. Marl 1 



6. White Lias 3 



7. Marl , 1 



8. White Lias 3-1 



9. Marl 3 



Lower Lias. 



10. Insect and Crustacean 



Bed 1 in. to 3 



ft. in. 



ni. Marl 



12. Ostrea-bed 



13. Ditto 



3 



2 



2 



14. Ditto 



15. Marl 



4 



3 



16. Ostrea-bed 



17. Marl 



j 18. Ostrea-bed 



1 19. Ditto 



4i 



2 



2 



2 



20. Marl 



1 



21. Ostrea-bed 



3 



22. Marl 



1 



23. Ostrea-bed 



3 



24. Marl 



6 



25. Ostrea-bed 



\26. Ditto 



2i 



3 



