MOLLUSC A (EXCEPT CEPHALOPODA). 
135 
Ptcrocera occani, Flcurotomaria rugata, Sowerbga Dukei, 
Asiarle riigosa, and many species of Trigonia. Note also 
the large borings of Lithodoinus. 
The shells of the Kimmeridge Clay are mainly from 
Weymouth, Dorset ; Wootton Bassett, Wilts ; the neighbour- 
hood of Oxford; and Hartwell, Bucks. The following are 
noteworthy : the large Pleurotomaria retimlata, the D-shaped 
Ostrea clcltoidea., the common and characteristic Exogyra vir- 
gxda, Gryphaea dilatata with its thickened hinge, well shown 
in sections, a Gryphaea with a supposed pearl, Protocardia 
\Cardium\ striatida, Astarte hartwdlcnsis, various Trigonias, 
Goniomya literata, and Thracia depressa. A slab of Kim- 
meridge Clay filled with Osirea lacvmsada is on the wall, 
and below it is the fine block of Coralline Oolite with over 
110 shells of Trigonia davellata figured in Damon’s “ Geology 
of Weymouth” (see our Plate VI.). 
The Coral Eag and Calcareous Grit are the chief British 
rocks formed during Sequanian or Corallian time ; they 
stretch across England, with occasional breaks, from Wey- 
mouth to Buckinghamshire, reappearing in Yorkshire, and 
are rich in fossils. Among the gastropods are Bourgudia. 
[^Pliadandki] stnata, Pscudomdania hcddingtoncnsis, Ncrinaca 
Goodhalli, and a spiny winkle TAttonna muricata. Lamelli- 
branchs are represented by Aledryonia gregaria, Chlaviys 
viinineus, Ctcnostrcon pcdiniforinis, Mytilus pcdinatu^, Tri- 
gonia triqudra, and many others. The numerous borings of 
Gustrochacna and Lithodomus in the coral masses bear witness 
to a shallow sea. It is interesting to contrast the richness 
and variety of the molluscan fauna that lived in the Corallian 
sea with the comparatively few species found in the clays 
above and below. 
The clay below is the Oxford Clay, well developed in 
Oxfordshire, and forming a more continuous band across 
England from Donset to Yorkshire than do the Corallian 
limestones. Within this tract the fossils are entirely marine, 
and those exhibited come chiefly from Weymouth, Christian 
]\lalford and Chippenham in Wiltshire, and Scarborough. 
The delicate character and shelly constitution of the Wiltshire 
specimens contrast with the coarser and stony appearance of 
the others. Characteristic forms are Alaria trijida with its 
long processes, the delicately spined Spinigera spinosa, Nucula 
ornata, Volsdla \_Modiola^ cuncata, and Pleuroniya recurva. 
Under Ostrea and Gryphaea are to be seen shells that have 
grown upon Trigonias and an ammonite and have assumed 
Gallery 
VIII. 
Table-case 
10 . 
Between 
Wall-cases 
6 & 7 . 
Table-case 
10 . 
Table-case 
11 . 
