

"Vol. 52.] STRATA BETWEEN THE KIMERIDGIAN AND APTIAN. 547 



Turning now to the consideration of the subdivisions of the same 

 series in other countries, I cannot add much to the correlations 

 already published in my paper on the Speeton fauna. 



As regards England, we see now that the Neocomian is here 

 more completely developed than in Russia, the zone of Hoplites 

 regalis being well represented at Speeton. If, however, we begin 

 the Neocomian with the bed containing Ammonites plicomphalvs 

 and ammonites of the group of Polyptychites, the beds D^ of 

 Speeton must be carried over to the Neocomian. I regard it as 

 possible that at some future time two distinct zones will be distin- 

 guished there, corresponding to the zones of Ammonites stenom- 

 phalus and of Polyptychites Keyserlingi. In Lincolnshire the Claxby 

 Ironstone should probably be considered as Cretaceous, while the 

 greater part of the Spilsby Sandstone appears to belong to the 

 Upper Jurassic (Aquilonian). 



In Germany all the zones of the JNeocomian seem to exist (a good 

 specimen of SimbirsJcites progrediens, from Salzgitter, is preserved 

 in the Gottingen Museum), but the stratigraphy of the beds presents 

 many difficulties and requires further researches. I am therefore 

 able to give only a provisional classification of the faunistic sequence 

 of this region. (See Table facing p. 548.) 



In the southern regions of Europe we have to consider the question 

 of the Upper Tithonic and Berrias beds. In Russia the Hoplites 

 closely related to Upper Tithonic types make their appearance in the 

 uppermost zone of the Aquilonian, and in one region (government 

 of Riasan) some rare forms continue into the lower zone of the 

 Lower Neocomian. When this fauna shall have been sufficiently 

 studied, it promises to yield very interesting results, since very 

 nearly allied, and possibly identical, ammonites have been found 

 in South America, 1 and perhaps in Tibet. As for the Berrias of 

 Southern Europe, I am inclined to consider that this horizon, from 

 its close faunistic connexion with the Upper Jurassic, should be 

 ranged with that system. But since some Lower Neocomian forms 

 are found in it, and since in many areas it has been customary to 

 carry even the whole Berrias into the Cretaceous, it may be found 

 convenient, for the sake of working out a common classification, 

 to divide this transitional series between the two systems, placing 

 the Ardescian (with the Lower Berrias) with the Jurassic, and the 

 uppermost Berrias with the Cretaceous. This question must, how- 

 ever, be further studied in the region where the typical Ardescian 

 and Berrias are fully developed, and especially in the northern part 

 of that region. 



For the solution of this question it is necessary that one should 

 find the fauna with Hoplites Malbosi, Euthymi, etc., and also the 

 fauna with Oxynoticeras Qevrilianum and Marcousanum, in one and 

 the same section, so that the mutual relations of these two faunas 

 could be exactly studied ; and this appears to be a very delicate 

 and difficult task. 



1 Hoplites mendozaniLs, Zeitschr. d. Deutsch. geol. Gesellsch. vol. xliii. (1891) 

 p. 399 & pi. xxv. fig. 2. 



