150 Lankester— Crag. 
living species common to the Red, Coralline, and Upper Antwerp 
‘Crags. A great number of facts may be gathered in this way from 
the tabular statement, bearing in an important manner on the rela- 
tions of the various beds; but in all cases it must be strictly taken 
into consideration that the total of the known Molluscan Fauna of 
the Red and Coralline Crags is more than double that of the Upper 
or Middle Antwerp Crags, and. also that the Lower Antwerp Crag 
has a larger known fauna than the higher Crags of Belgium. 
Relations of the Lower Antwerp Crag.—By some authors the 
Black Crag of Antwerp has been considered as of Miocene age; by 
others, as the equivalent of our Coralline Crag. The truth is, no 
doubt, between the two opinions ; and, as above stated, the Lower 
Antwerp Crag is a representative of a Lower Pliocene period. 
Besides the species which are common to the other strata, there are 
some dozen species found in the Black Crag which occur again in the 
Coralline Crag only; but there can be little doubt that were the 
Upper and Middle Crags carefully searched, these forms would turn 
up. An undoubted relation exists between the Black Crag and the 
higher, so-called Miocene, beds of Bordeaux and Vienna. In fact, 
the resemblance is so close, that it appears necessary to consider 
them as belonging to the same epoch. If the higher Bordeaux strata 
are Miocene, then also are the Lower Antwerp Crags, and vice versa. 
The Black Crag appears to be inseparable from the Middle and 
Upper beds. The presence in this deposit of such shells as Cy- 
prina Islandica, C. rustica, and forty-two others, which are found 
in the two series above, connects them most intimately: rather than 
they should be separated, it is necessary to consider the higher | 
‘Miocene’ beds of Bordeaux and Vienna as being really Pliocene. _ 
Evidence of the Existence of Middle Pliocene Strata in England.—It 
may very well be asked—have we no representative, then, of the Ant- 
werp Middle and Lower Crags in this country? As far as regards 
the Lower Crag, I am afraid the answer must be in the negative; 
but with respect to the Middle Crag, there is a little more to be said. 
The catalogue of the Molluscan Fauna of the Middle Crag of Ant- 
werp undoubtedly shows its superior antiquity to the Red and Coral- 
line Crags. M. Van Beneden has described from that deposit nume- 
rous remains of Cetacea, belonging to the genera Squalodon, Ple- 
siocetus, Dioplodon, Choneziphius, &c., and has also shown me the 
tooth of a Seal and the fragment of the tusk of an enormous Morse 
which I have elsewhere called Z'richecodon.* These are associated 
with the teeth of Carcharodon megalodon and others. None of 
these fossils are sea-worn. Throughout the Red Crag we find 
much-rolled and worn vertebrate remains corresponding, in species, 
to those of Antwerp. Can it be doubted that these are the débris of 
a formation which existed in England formerly, but was broken up 
by the Red Crag Sea? 
* I have lately communicated a notice of the tusk of this animal to the Geo- 
logical Society, having obtained specimens of it from our Red Crag some time 
since ; and I have proposed to call it Zrichecodon Hualeyz. 
