542 
THE CRETACEOUS ROCKS OF BRITAIN. 
(Op. cit., p. 470), and for this purpose he proposes a special classifi¬ 
cation of these sediments. Some are terrigenous in the sense 
indicated by Messrs. Murray and Renard, and some are truly 
pelagic, but, as he points out, there are others which contain little 
terrigenous material, and which yet cannot be called pelagic, such,. 
for instance, as beds which are largely composed of Bryozoa, or of 
the remains of siliceous sponges ; for these he proposes the term 
“ benthogene,” which might be translated as benthal.* 
Using these terms, he tabulates the varying characters of the 
Turonian sediments of the Paris basin in the following manner : — 
Zones. 
Gulf of Mons. 
Nord. 
Centre. 
South-west. 
M. breviporus 
Ter. gracilis - 
In. labiatus ( = Rh. 
Cuvieri). 
Pelagic 
Pelagic 
Benthogene or 
terrigene. 
Terrigene. 
Pelagic. 
Terrigene 
Terrigene and 
benthogene. 
Pelagic or bentho¬ 
gene. 
In England the only Turonian deposit which might be calk d 
benthogene or benthal is the Beer Stone of Devon (see p. 506). 
If, then, there was land to the east and to the west of the Paris 
basin, and also, as is most probable, to the south over Central 
Prance, in what directions are we to look for possible openings 
and for connections between the Anglo-Parisian sea and the larger 
seas or oceans of the period ? 
It is well known that the Chalk, and especially the Middle and 
Upper divisions of the formation, occupy very large areas in central 
and eastern Europe. There can be no doubt that a broad sea 
spread eastward at this period from England through Belgium, 
Holland, Denmark, and Germany into Central and Southern 
Russia. There was also another sea in Southern Europe, the 
deposits of which are found in the Alpine region, and it is not 
improbable that this communicated with the more northern sea 
round both ends of a Central European island. The western 
end of this island and the connection of these two seas has been 
shown in a map drawn by Dr. W P. Hume to illustrate his paper 
on the “ Genesis of the Chalk.” f Another broad sea-space 
existed in the south of Prance, which is sometimes termed the 
Hippurite Sea by French geologists. 
The evidence for the communication between these seas and 
that of the Paris basin has been discussed by M. Caveux in the 
work already quoted (p. 561). He considers it certain that there 
was a wide and deep opening to the south across the region of 
*The term benthal has been used by Gwyn Jeffreys in a rather different 
sense, for he applied it to deep-sea (pelagic) deposits. It would be more 
useful if employed in the sense suggested by M. Cayeux for deposits 
which are neither terrigenous nor pelagic. 
t Proc. Geol. Assoc., Vol. xiii. p. 211 (1894) 
