LOWlCR CHALK—NORTH-WEST OF FRANCE. 
253 
Another remarkable bed is that numbered 14, characterised 
by the presence of brown phosphatic nodules. This is rich in fossils, 
and especially in Cephalopoda, all the species so common in our 
Chalk Marl occurring here, though often as casts and fragments. 
The following is a list of the species found by Mr. Hill in this bed : — 
Nautilus, sp. 
Hamites simplex % 
Scaphites sequalis. 
Ammonites [Hoplites] falcatus. 
,, [Acanth.] Mantelii. 
„ [Schloenb.] Coupei. 
[ „ ] varians 
Turrilites costatus. 
„ tuber culatus. 
Aporrhais sp. 
Avellana cassis. 
Exogyra conica. 
Ostrea canaliculata 
Pecteu asper. 
Pecten elongatus. 
„ puzosianus. 
„ (Neithea) eequicostatus. 
,, „ 5-costatus. 
Terebratella Menardi. 
Rhynchonella dimidiata. 
„ convexa. 
„ grasiana. 
Caratomus rostratus. 
Cidaris vesiculosa. 
Glyphocyphus radiatus. 
Holaster subglobosus. 
Discoidea subuculus. 
Pseudodiadema ornatum. 
Holaster subglobosus sets in with the Ammonites at the base of 
the formation, but is not common till Bed 12 is reached, and com 
tinues common up to Bed 15. The greyish-white chalk above 
this resembles beds of a similar colour in our Lower Chalk except 
for the frequent layers of cherty flints. Fossils, however, are scarce 
in it. In this section there does not seem to be any representative 
of the marl with Actinocamax plenus ; for this whitish chalk is 
succeeded directly by nodular chalk with Inoceramus mytiloides. 
I have little doubt that the bed with brown phosphatic nodules 
(No. 14) corresponds with the well-known fossiliferous horizon 
of Mont Ste. Catherine, near Bouen, for this horizon is near the 
top of the Cenomanian. The following particulars of this section 
are given by Messrs. Lennier and Bucaille,* their measure¬ 
ments in metres being given approximately in feet : — 
ft. in. 
Nodular chalk ( = the Mel bourn Bock), see p. 496 - - 6 6 
Grey or greenish marly chalk, weathering into laminae ; 
. this is the horizon of Actinocamax plenus - - - 0 8 
Layer of nodules formed of hard greyish chalk, greenish 
on the outside.14 
Sandy micaceous chalk with some glauconite, becoming 
nearly white when dry, Holaster subglobosus , Am. navi- 
r 1 cularis . ----40 
Soft grey glauconitic chalk with many small brown nodules 0 8 
Fossiliferous bed, formed of glauconitic chalk, hard stone, 
« and yellowish sand, with many Cephalopods and other 
fossils, Am. rotomagensis, Scaphites cequalis , etc. - - 1 4 
Yellowish-grey glauconitic chalk, with many small con¬ 
cretions of sandy limestone, Inoc. striatus (very common) 
and Discoidea subuculus -- - 6 6 
* 
Bull. Soc. Geol. Norm., Vol. vi. p. 389. 
