WAAGEN IJPPEE JUEASSIC STRATA. 



15 



tain Coral-reefs ; these d'Orbigny included in his ' Etage Corallien,' 

 with the view of preserving in the French language the terms Coral- 

 rag, CoralHne Oolite, &c., which had already been used by English 

 authors. The term became speedily adopted, and the same horizon 

 was believed to have been recognized in very various districts ; but 

 whether these deposits were really identical with those originally 

 termed Coral-rag by English geologists is a question which, until 

 very recently, has not been fully discussed ; and in this pamphlet the 

 author endeavours to contribute to its solution. 



Dr. Waagen enumerates the subdivisions adopted in England, 

 from the Purbeek beds to the Kellovi^ay rock inclusive, remarking 

 that he uses this classification on account of its priority, although a 

 division of the beds, much better characterized palseontologically, 

 has since been deduced from observations in most of the Jura-dis- 

 tricts of Central Europe. Another reason is that having studied 

 these strata in the vicinity of Weymouth, he is better enabled to give 

 the results of his observations by using our classification. 



The author then gives detailed sections of the beds at Ringsted 

 Bay, near Weymouth, with Ksts of the fossils he collected from them, 

 and makes some observations on the general character of the strata 

 and their parallelism vpith the continental divisions. The result of 

 his examination he gives in a tabular form as foUows : — 



g 



baj 



B 

 I 



1 



o 



Local Horizons. 



English Divisions. 



Zone of Trigonia gibiosa . . 



J 1. Portland Stone. 

 \ 2. Portland Sand. 



Region of 

 Orbicula latissima and 

 AcanthoteutJiis spedosa . . 



y3. Kimmeridge Clay. 



Region of 

 Ammonites mutabilis and 

 Exogyra virgula 



Region of 

 Ammonites alternans and 

 Rhynchonella inconstans . 



Region of 

 Cidaris jlorigemma 



' 4. Upper Calcareous Grit. 

 " 5. Oxford Oolite *. 



Region of ■ 

 Ammonites Martelli 



I 6. Lower Calcareous Grit. 



Region of 

 Ammonites biarmatus .... 



1 7. Oxford Clay. 



* Coi-al-rag. 



e2 



