Tol. 69.] UPPER JURASSIC STRATA OF ENGLAND. 427 



this comes Kimmeridge Clay, which thus probably begins here with 

 the zone containing Pictdnice. 



It can, therefore, be recognized that over the whole region 

 described the change of facies between the Kimmeridge Clay 

 and the Portland Sands occurs at one and the same time, The 

 facies-division between Kimmeridge Clay and Corallian is, however, 

 not chronologically constant, but changes to the extent of several 

 zones even within short distances : thus, for instance, between 

 Weymouth and Abbotsbury, or between Westbury and Swindon. 



As regards other localities, I will merely emphasize the fact that 

 the Kimmeridge Clay exposed at Market Easen (Lincolnshire), 

 which has furnished the splendidly-preserved ammonites that 

 constitute a particular embellishment in many collections, has 

 only yielded the fauna of the zone of Easenia cymodoce and R. 

 uralensis. 



The foregoing account forms the first publication of a part of my 

 comprehensive studies on the zonal subdivision and correlation of 

 the Upper Jurassic formation (in the German sense) of Middle and 

 North-Western Europe. The investigation of the faunas will be 

 dealt with in separate monographs of the genera, to be published in 

 ' Palseontographica.' 



Finally, I wish here to express my warmest thanks to all 

 those gentlemen who, by valuable advice and information and by 

 giving access to collections, as well as by the loan of fossils, have 

 supported and furthered my studies : particularly to Dr. A. Smith 

 Woodward, Prof.W. J. Sollas, Mr. G. C. Crick, Dr. F. L. Kitchin, 1 

 Mr. S. S. Buckman, 1 Mr. Gore, and Mr. Barnes, in addition to 

 others. 



1 



Appendix : Ammonite Names. 

 Ringsteadia, gen. nov. 



Genotype, Ammonites pseitdocordatus Blake, emend. Salfeld. 



Blake's illustration, in Q. J. G. S. vol. xxxiii (1877) pi. xiii, fig. 1, 

 scarcely reproduces the characters of the genus. Since the original 

 specimen cannot be found, I take as type of the genus that 

 ammonite from the same locality which agrees most closely with 

 Blake's description. The following must rank as synonyms of 

 A. pseudocordatus Blake, emend. Salfeld : — 



1888. Ammonites mutabilis R.Damon, 'Supplement to the Geology of Wey- 

 mouth & the Isle of Portland ' pi. xvi, fig. 1. 



1909. Proplanulites mutabilis R. Douville, Bull. Soc. Geol. France, ser. 4, 

 vol. ix, pi. vii, tig. 1 & pi. viii, fig. 1. 



The name is derived from Ringstead Bay, near Weymouth 

 (Dorset). 



1 I am also indebted to Dr. Kitchin for translating this paper, and to 

 Mr. Buckman for bringing together my results in the form of the tablo 

 which follows (p. 428). 



