MOLLUSCA (except CEPHALOPODA). 
129 
Pliocene. The shells are primarily arranged under the 
formations from whicli tliey come: the Norwich Crag and 
the Eed Crag, both of Astian age ; the Coralline Crag, of 
Plaisancian age ; the Lenham beds of Kent and the St. Erth 
beds of Cornwall, both probably Plaisancian. No rocks of 
Sicilian age occur in Britain. The Crags are well known 
for their abundant molluscaii fauna, of which further 
examples, mostly collected by the late Eobert Bell, are 
exhibited in Cases A 2 (Lamellibranchia) and A 3 (Amphi- 
neura. Gastropoda, Scaphopoda). The fauna is essentially 
marine, but a few non-marine shells invite speculation as to 
the cause of their occurrence. From the Coralline Crag of 
Comer, Suffolk, come some fine examples of the gastropod 
Voluta Lamhcrti, one of them inches (24 centimetres) 
long. The Eed Crag furnislies Ncptunm antiqua wound in 
a reverse direction to the usual one, Ci/prina mstica, and 
Fholas cjjlindrica. In the Norwich Crag again appears Acila 
Cohboldiac, and Bittium rdiculalum is again found in the 
St. Erth beds. 
Oligocene. Shells of this Epoch come from the llam- 
stead or Hempstead Beds of Eupelian age, the Bembridge 
Limestone (Tongrian), and the Osborne and Headon Beds 
(Priabonian). These formations were deposited in an estuary 
where now are the Isle of AVight and the south of Hamp- 
shire. One may notice particularly Amplddromus \^Bidiimcs\ 
cllipticus wound in a reversed or left-handed coil, with many 
species of the gastropod genera Viviqmrm, Melania, Limnaca, 
and rianorhis momphalm, and the lamellibranchs, Ostrea, 
Corhicida, and Volsclla \Modiola\ The eggs of some large 
gastropod, Bidimm or an ally, will be seen preserved in 
Bembridge Limestone. A slab of Headon Limestone almost 
entirely composed of the shells of a fresh-water snail, 
Lininaea longiscata, is fixed on the wall. 
Eocene. Here are the Bartonian shells of Barton, the 
Lutetian of Bracklesham, and the Landenian shells from the 
London Clay, Oldhaven Beds, AVoolwich and Eeading Beds, 
and the Thanet Sands. Except for the Oldhaven and 
AVoolwich Beds, which contain both estuarine and marine 
fossils, all these formations are purely marine. Many of 
the specimens exhibited have been figured by G. A. Mantell, 
James Sowerby, F. E. Edwards, and others. A large 
specimen of Gardita planicosta is marked so as to explain 
the terms applied to the various parts of a lamellibranch 
shell. Here also is the curious burrowing lamellibranch 
Gallery 
VIII. 
Table-case 
2 . 
Table-cases 
2 & 3. 
Centre- 
cases A2 
A3. 
Table-case 
3. 
Between 
Wall- cases 
2 & 3. 
Table-case 
4. 
Table-case 
5. 
Table-case 
4. 
