viii CRETACEOUS LAMELLIBRANCHIA. 



F. Dixon on ' The Geology and Fossils of the Tertiary and Cretaceous Forma- 

 tions of Sussex' (1850 or 1852). This contains excellent figures of some Chalk 

 Lamellibranchs by J. de C. Sowerby, but the descriptions of the species are very 

 brief, or in some cases even omitted ; moreover, the type-specimens appear to have 

 been lost, and in many instances their original locality is not stated. 



The latest work on the Lower Cretaceous Lamellibranchs of England is that by 

 W. Keeping on ' The Fossils and Palgeontological Affinities of the Neocomian Deposits 

 of Upware and Brickhill ' (1883). Most of the original specimens described in 

 that memoir are preserved in the Cambridge Museum. 



A few papers have been published from time to time on the Lamellibranchs of 

 special horizons, such as those of the Cambridge Greensand by Seeley (1861) and 

 by Jukes-Browne (1875, 1877); those of the Faringdon Greensand by Sharpe 

 (1853) ; those of the Chalk of Cambridge by Etheridge (1881) ; and those of the 

 Chalk Rock by myself (1897). Various papers dealing with Cretaceous strati- 

 graphy give brief notes on some of the species of Lamellibranchs. 



The distribution of the Cretaceous Lamellibranchs of England is indicated in 

 many books and papers on stratigraphical and local geology. The more important 

 of those dealing with the Lower Cretaceous deposits are : — (i) on the Isle of Wight 

 by Fitton (1847), and by Bristow, Reid, and Strahan (1889) ; (ii) on the Weald by 

 Topley (1875) ; (hi) on Faringdon by Phillips (1871) ; (iv) on Lincolnshire by 

 Keeping (1882) and others ; (v) on Speeton by Lamplugh (1889, 1896). 



The distribution of Lamellibranchs in the Gault is given in great detail by 

 Price (1879) ; in the Upper Greensand of Blackdown and Haldon by Downes 

 (1882), in that of Warminster by Jukes-Browne (1896), and in the Upper Green- 

 sand and Chloritic Marl of Maiden Bradley by Jukes-Browne and Scanes (1901). 

 Amongst the more important works dealing with the zonal distribution in the Chalk 

 are those by Barrois (1876), Meyer (1874), Jukes-Browne and Hill (1886-96), 

 Griffith (1891), and Rowe (1900, 1901, 1903). 



The distribution of Cretaceous Lamellibranchs in different districts is also 

 indicated in numerous memoirs issued by the Geological Survey other than those 

 above referred to ; and revised lists showing the general distribution of the species 

 in the Upper Cretaceous rocks are given in the memoir on ' The Cretaceous Rocks 

 of Britain,' by Jukes-Browne, vol. i, 1900, pp. 453 — 487, and vol. iii (in the press). 



The following monograph deals with the Lamellibranchs of all the Cretaceous 

 deposits of England, with the exception of the Wealden formation, which, it is 

 thought, will be more satisfactorily studied in connection with Mollusca of the 

 Purbeck Beds. The species found in the lowest part of the Speeton Series in 

 Lincolnshire and Yorkshire are, as a matter of convenience, included in this work, 

 although they may possibly prove to be of Upper Jurassic age. The families are 

 here considered generally in the order given in Pelseneer's classification. 



