ZONE OF AMMONITES PLANORBIS. 



55 



and Wilmcote, in Warwickshire ; and at Pinhay Bay and Up Lyme, in Dorset. I purpose 

 giving a detailed description of the most typical sections in each county. 



SomerscfsJiire. — At Street the strata are nearly horizontal and undisturbed, and there- 

 fore admit of accurate measurement. The following section of Mr. Cree's quarry I have 

 compared with like sections afforded by the quarries of Messrs. Seymour, Underwood, and 

 Talbot in the same parish ; and find that the variation is so inconsiderable that any one 

 may be said to represent the others, both as regards the sequence of the beds and the 

 fossils they contain. 



Section of the Zone of Ammonites planorbis, at Street, Somerset. 



LiTHOLOGY. Organic Remains ; and the Local Names of Beds. 



No. ft. in. Planorbis Series. 



1. Light-coloured marly clay 3 "Top Bed." Saurian bones and Ammonites 



planorbis. 



2. Lio;lit-coloured Lias limestone 9 Ammonites planorbis m moxAdiS.. 



3. Yellowish laminated shale, splitting up Ichthyosaurus intermedins, Ammonites planorbis, 



into thin layers 3 Lifna punctata, and Isastraa Murchisoni. 



4. Light-coloured shaly limestone 4 Ammonites plano7-bis, compressed. 



5. Hard gray limestone 7 "Building-stone." Ammonites planorbis, on the 



top of the bed, Lima punctata and Lima 

 gigantea. 



6. Dark-gray shale 3 Ammonites planorbis, and muricated spines of 



Cidaris, Edwardsi. 



7. Dark-gray limestone G "Corn-sized building-stone." Spines of Cidaris 



and bones of Ichthyosaurus tenuirostris. 



OsTREA Series. 



,'8. Dark laminated shale 4 Ostrea liassica. 



9. Dark -gray limestone 5 " Five-inch building-stone." Ostrea liassica. 



10. Dark shale ..; 3 Ostrea liassica. 



11. Dark-gray limestone 6 " Six-inch building-stone." Cardinia crassiuscula, 



Lima punctata, and Ostrea liassica. 



12. Dark shale 6 



13. Grayish hard limestone, consisting of "The Whetstones." Best paving-bed. Fossils 



two 4-inch beds 8 rare : Ostrea liassica and Modiola minima. 



14. Hard dark marl 9 "Saurian bed." Many Saurians have been ob- 



tained here. Ichthyosaurus intermedins and 

 Plesiosaurus Hawkinsii (British Museum). 

 Jaws of Saurians and Fishes. 



15. Grayish fine-grained limestone 3 "The Cream-bed." Fine-grained paving - stone. 



Ostrea and Modiola. 



16. Brownish limestone 4 "Red Liver." Paving-stone. Few fossils. 



17. Dark-coloured limestone 4 The "Black stone," used for large paving-slabs; 



some of them 10 ft. by 5 ft. Modiola minima, 

 Ostrea liassica, Myacites, and Bhynchonella 

 variabilis. 



