Gasteropoda and Lamellilranchiata. 49 



Opposite Table-case 94, in the centre of the gallery, is a GALLERY 

 large block of Portland Oolite from the '' lloach-bed," Isle ^"^• 

 of Portland, almost entirely composed of the casts of Trigonia 

 gihhosa, Natica elegans, Cardium dissimile, etc. 



Fig. 91. — Trigonia costata, Park. Oxfordian: Osmington, Dorset. 



Between Wall-cases 5 and 6, two slabs of Portland Oolite are 

 fixed on the wall : one contains Perna Bouchardi and Peden 

 lamelloms ; the other is full of the casts of Cerithium concavum. 



A slab of Kimeridge Clay placed on the wall between Wall- 

 cases 6 and 7 exhibits fine specimens of Ostrea Iceviuscula ; 

 there is also a block, of Coralline Oolite full of specimens of 

 Trigonia clavellata from near Weymouth. In Table-case 91 are 

 placed specimens of Pecten Valoniensis from the Rhaetic of "^^^^ q" 

 Westbury Cliff, and Trochus Waltoni from Beer, Somerset; also 

 impressions of Mollusca from the Upper Keuper of Warwick- 

 shire ; and remains of Monotis, Schizodus, Rissoa, etc., from the 

 Permian of Durham. 



Pal-siozoic Mollusca. — Table-case 90 contains the Carboniferous Table- 

 and Devonian Mollusca ; of the former may be mentioned Anthra- ^^^^ ^• 

 cosia, Carhonicola, Myalina, etc., from Coalbrookdale, figured and 

 described by Sowerby in Prestwich's "Geology of Coalbrookdale." 

 The Gasteropods include JEuomphalus, Leveillia, Bellerophon, etc. 

 The Devonian Mollusca are represented by Anodonta Jukesii 

 and the genus Murchisonia. The Silurian and older Mollusca 

 comprise the genera Euomphalus from the Wenlock Limestone, Table- 

 with its operculum in situ ; Trematonotus, with a central series of 

 perforations; Maclurea from; the Durness Limestone (Ordovician) 

 of Scotland. Prom the Cambrian are forms referred to the genera 

 Glyptarca and PalcBarca, etc. 



B 



