ANNIVERSARY ADDRESS OF THE PRESIDENT. Ixi 



The part of the " Monograph of the MoUusca from the Great 

 Oolite," issued for 1853, is devoted to the Lamellibranchiate 

 Bivalves (not yet completed), of which 1 16 species are here described 

 and figured. Of these 36 are new to science, and 24 continental 

 forms new to British lists. The authors remark that a large pro- 

 portion of the Oolitic Lamellibranchiata had shells whose hinges 

 were either a lengthened hinge-plate with a parallel series of trans- 

 verse or oblique teeth, i. e. a hinge of the Arcoid type ; or a tooth- 

 less hinge of the Mytiloid and Myoid types ; or a hinge with a 

 ligamentary fossa only (as Pecten and its alhes) ; or with the liga- 

 ment inserted in distinct pits {Perna and its allies). Shells with 

 cardinal teeth constituted only a minority : hence the Veneroid forms 

 of the oolites are especially few in number. The preceding parts of 

 this valuable monograph were equally rich in facts of a general 

 character, and consequently now so well known that they need not 

 be recalled here. 



Professor Owen's instalment for 1853 towards his great mono- 

 graph of the British Fossil Reptiles includes the Chelonia Paludinosa 

 of the Wealden and Purbeck beds. Eight species are described and 

 figured (six of them new), members of the genera Pleurosternon, 

 Chelone, and Platemys. Those of the first named genus (four species) 

 are all from the Purbecks, those of the two latter from the Wealden 

 beds, properly so called. So far, then, the Eeptilia tend to support 

 the views that I have promulgated, after a careful and extended 

 study of the Dorsetshire Purbecks and Wealdens, to the effect that 

 these groups are not members of one series of freshwater beds, but 

 perfectly distinct, and indeed belonging in part (the Purbecks) to the 

 Lower, and in part (the Wealdens) to the Upper Mesozoic epoch. 

 During the past summer I have had occasion again to go over the 

 sections in the Isle of Purbeck, deliberately and in minute detail, 

 and I remain confidently of the opinion which I put forth at the 

 Edinburgh Meeting of the British Association in 1850. The detailed 

 memoir on this subject, to be amply illustrated, is in progress, and if 

 possible will be published in the course of the present year. In the 

 mean time I do not regret the delay, since I have thereby been 

 enabled to work out deliberately numerous points requiring time for 

 their elucidation. 



The monograph of the Crag MoUusca is fast advancing towards 

 completion, and the fresh part is as remarkable as the former ones for 

 the fulness of knowledge of the subject that has throughout charac- 

 terized this important contribution to British Palaeontology. Mr. 

 Wood has spared no pains, and has worked from the most ample 

 materials. The genera of Bivalves with cardinal teeth occupy this 

 portion of his treatise. Of these 5/ species are enumerated; not a 

 few are now fully described and figured as British fossils for the first 

 time, the previous notices of them having been restricted to a bare 

 mention. I would earnestly urge upon continental geologists the 

 consideration of the results at which Mr. Searles Wood has arrived 

 in this most careful monograph. There cannot be a doubt that the 

 epoch (or rather epochs) of the Crag, was as distinct from that of the 



