FORMATION OF NORTHERN GERMANY. 143 
feet of yellowish oolitic iron ore, and beneath ofa dark gray clay 
about the same thickness. Neither of these parts contains any 
fossils, but from their stratifical relations they may probably be- 
long to the Hils-clay. 
Some former geologists referred the argillaceous deposit, which 
was first observed at Elligserbrink, to the Oxford clay, others 
to the Kimmeridge clay; and I myself have since considered it 
as the youngest member of the Jura: but subsequently I became 
convinced, from observations at the foot of the Deister, that it 
was superior to the Weald clay; and, at a later period still, I 
recognised in it the Speeton clay of English geologists. That 
the Speeton clay is in England considered, without sufficient 
reason, as an equivalent of the gault, is evident from the rela- 
tions of stratification in the Hils-mulde, where the gray chalk 
distinctly overlies the argillaceous mass ; and moreover from the 
distinctness of its fossils from those of the gault. 
The following fossils appear to be restricted to the Hils-clay 
in Germany :— 
Modiola pulcherrima. Hamites obliquecostatus. 
Isocardia angulata. ...  fissicostatus. 
Panopzea plicata. ...  Yraricostatus. 
Fistulana constricta. ...+  Capricornu. 
Belemnites pistillum. ...  sexnodosus. 
Ammonites rotula. ...  decurrens. 
asper. Serpula Phillipsii. 
Hamites Beanii. 
Numerous fossils of the Speeton clay are found also in the 
Hils-conglomerate ; for instance-— 
Heteropora ramosa. Pecten cinctus. 
Pentacrinites annulatus. Avicula macroptera. 
Crania irregularis. Modiola rugosa. 
Terebratula multiformis. Belemnites subquadratus. 
aes oblonga. Ammonites noricus. 
oe longa. Serpula antiquata. 
Exogyra sinuata. Gly phea ornata. 
..- _ haliotoidea. 
Other species ascend in Germany from the Hils-clay into the 
gray chalk; for instance— 
Pecten asper. Hamites gigas. 
Thracia Phillipsii. Catopygus carinatus. 
Mya elongata. 
