A guide to the fossil invertebrate animals in the Department of geology and palaeontology in the British museum (Natural history) ... / With 7 plates and 96 textfigures.

British Museum (Natural History). Department of Geology

Date:: 1911

Credit: A guide to the fossil invertebrate animals in the Department of geology and palaeontology in the British museum (Natural history) ... / With 7 plates and 96 textfigures. Source: Wellcome Collection.

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$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.$