Cretaceous System of the Crimea— Neocomian. 539 
doubted type of what foreign geologists call the Terrain Néocomien, 
I would here suggest that the greater part, if not the whole, of the 
series may be paralleled in the south of England, and that too with- 
out consulting other sections than those described by Dr. Fitton, 
and the natural phenomena which he has so faithfully represented. 
The uppermost seven divisions of the Crimea are all evidently re- 
ferrible to our chalk and chalk marl, and contain many of our well- 
known fossils, the only striking difference consisting in the associa- 
tion of Nummulites and Cerithium giganteum, with the Trigonie and 
Ostree of the uppermost chalk. The beds 8 and 9, Crate chloritée 
and Gres vert, containing, amid Hxogyre and some cretaceous fossils, 
the Pecten quinque-costatus and P. orbicularis, most unequivocally 
represent our Upper Greensand or “ malm rock.” The marly strata 
which lie beneath such beds are therefore, we may fairly presume, 
the representatives of the English gault; and, lastly, the yellow lime- 
stone and sand, immediately beneath it, which forms the Neocomian 
of M. Dubois, may, after all, be considered the equivalent of our 
Lower Greensand, or the expansion of its lowest beds which pass 
into the Wealden. 
I have always regretted that so few foreign geologists have ob- 
tained an adequate idea of the dimensions and importance of the 
third or inferior division of lower greensand as exhibited on the 
southern shores of the Isle of Wight (Atherfield Rocks). In France 
the formation has been little recognized beyond the Boullonnais, 
where it has already almost lost its distinctive characters, and where 
there are no longer the divisions of upper, middle and lower beds, 
each, as shown by Dr. Fitton, characterized by peculiar fossils. In 
the south and east of France, where upper greensand and gault 
abound, it now appears* that the base of the Cretaceous system is 
composed of limestones identical with those of Neufchatel, and which, 
participating in all the flexures of the chalk, are usually broken off, as 
in the Crimea, from the Jurassic system. 
It has been suggested that the Neocomian limestones may re- 
present the Wealden of British geologists. But this is not, so far 
as I can judge, safe reasoning; for the latest researches of Professor 
Owen would lead me to believe, that the Saurians of that great 
estuary formation are much more nearly allied to those of the Oolitic 
or Jurassic epoch than to those of the Cretaceous period; and 
Agassiz has assured us that the fishes of the Wealden are entirely 
distinct from those of the chalk. 
I have before expressed my opinion on the head of Neocomian, 
both to French and English geologists+, and I now repeat it, more 
however as a stimulus to those who have the means to settle this 
point accurately, and not because I entertain any objection to the 
foreign use of the word. The term may, indeed, be very well and 
* See discourse of last year. [Phil. Mag. S. 3. vol. xx. p. 541.] 
+ In referring to an opinion which I expressed at the meeting of the 
Geological Society of France in 1839 (Bull. Soc. Geol. tom. x. p. 392 et 
seq.), 1 beg to say, that it is specially to the Greensand as the chief equiva~ 
lent to which I refer, 
202 
