234 PHOCEEDIKGfS OP THE CfEOLOGflCAL SOCIETT. [Jan. 22, 



of MM. Lejmerie, Cornuel, Longuemar, D'Archiac, and others, the 

 middle division of the I^eocomian wonld appear to be much less per- 

 fectly represented than either the upper or lower divisions. 



"When we pass beyond the limits of the Anglo-Parisian basin, the 

 difficulty of correlating the different foreign deposits with our York- 

 shire beds becomes, as might be expected, greatly increased, the more 

 so from the wide discrepancies of opinion which exist among French 

 geologists concerning the true stratigraphical relations of some of 

 their beds. Without, however, trespassing on these fields of con- 

 troversy, I may state that the extensive series of deposits, consist- 

 ing principally oiivhite limestones, which overlie the true K'eocomian 

 limestones (which are generally of a yellow colour) in Switzerland 

 and South-eastern France, and are especially characterized by the 

 abundance of Chama Ammonia and other species of Rudisfes, appear 

 to represent the Middle j^eocomian and that part of the Speeton 

 Clay which I have been describing. 



Other deposits, which appear to be of the same age, exist in the 

 south of Spain, the north of Italy, in Austria, in the province of 

 Constantine in Northern Africa, and probably in IS'ew Granada. 



C. Loiver Neocomian. — The third division of the Speeton Clay is 

 seen at the lower portions of Middle and 1'5'ew Closes Cliffs, the upper 

 parts of these cliffs being entirely concealed by drift. In subdividing 

 this series of beds, I shall avail myself of the limited vertical ranges 

 of several groups of Ammonites found in it. The sections into which 

 the series thus naturally falls are as follows : — 



a. Zone 0/ Ammonites Speetonensis, T. Sf B. — This consists of 

 about lUO feet of dark-blue clays, containing fossils in the form of 

 pyritous casts, Ammonites being particularly abundant. The prevail- 

 ing species is that which gives its name to the bed, and which is, as 

 far as I yet know, perfectly characteristic of it. Belemnites jaculum 

 is still abundant throughout this bed ; and towards its lower part 

 occur specimens of Ancyloceras, either enclosed in claystone nodules 

 or mineralized by pyrites. Exogyra sinuata, of the typical form, is 

 found but rarely in this bed ; but the little variety called E. suhpUcata 

 by Eomer occurs, and is, I believe, entirely confined to this zone. 



h. Zone 0/ Ammonites Noricus, Schloth. — This bed, like the last, 

 which it resembles in hthological characters, is very well charac- 

 terized by a group of Ammonites. Belemnites jaculum here becomes 

 exceedingly rare, as do also the species of Ancyloceras ; in the whole 

 of this bed, which is about 50 feet thick, I have been able to obtain 

 but a comparatively small number of species of fossils. 



c. Zone 0/ Ammonites A stierianus, UOrh. — The lowest beds of 

 the Neocomian series at Speeton are extremely well marked, both 

 by their lithology and by their palaeontology. They consist of from 

 50 to 100 feet of dark-coloured shaly clay, highly inipregnated with 

 pyrites. Unfortunately, owing to this last circumstance, all the 

 smaller and more delicate fossils are rapidly destroyed by the action 

 of the air. This bed may always be easily recognized by its shaly 

 character, and by its fragments being constantly coated with a yel- 

 lowish-white efflorescence, consisting of basic sulphate of iron. 



