Yol. 52.] OP THE CHALK BOCK. 71 



synonymy I shall not, except in a few cases, include references to 

 works in which the species are simply recorded, but only to those 

 in which some description occurs. 



The preservation of the fossils in the Chalk Eock is moderately 

 good, but the cephalopoda have scarcely ever the shell preserved. 

 The gasteropoda also occur most frequently as casts, but in nearly 

 every species at least one or two specimens have been found with 

 the shell remaining ; and much information has been obtained by 

 taking wax or gutta-percha casts of the external moulds. In Ostrea 

 and Spondylus (Dianchora) the shell is present, but in most of the 

 other lamellibranchs it has disappeared. The brachiopoda and 

 echinoidea have nearly always, as might be expected, the shell pre- 

 served. The corals are in the form of casts in almost every case. 



My work is based to a large extent on the collection from Cuck- 

 hamsley (Berks) made by the late Mr. Montagu Smith, of Trinity 

 College, and presented by his friends to the Woodwardian Museum ; 

 but for the loan of many specimens, which have been of much 

 service, I am greatly indebted to several friends and correspondents, 

 of whom I would especially mention Mr. W. Hill, of Hitchin, 

 Dr. J. Morison, of St. Albans, Mr. C. Griffith, of Winchester, and 

 Mr. E. M. Brydone, of New College, Oxford. I have also to thank 

 Dr. A. "W. Eowe, of Margate, and Mr. James Saunders, of Luton, for 

 allowing me to examine their collections and for other valuable 

 help ; while, in the British Museum and the Museum of Practical 

 Geology, Mr. G. C. Crick and Mr. E. T. Newton have generously 

 helped me in examining the specimens under their charge. Mr. 

 Jukes-Browne has also kindly given me advice concerning the range 

 of some of the species. 



In order to study more carefully the species described by Con- 

 tinental palaeontologists, I have visited the Museums of Prague, 

 Dresden, Berlin, Hildesheim, Hanover, Brussels, and Paris ; and I 

 would here express my gratitude to the authorities of those institu- 

 tions for the facilities given me. 



Literature. 



The following is a list of works in which descriptions of the Chalk 

 Eock have appeared : — 



1. A. C. Eamsay, H. W. Beistow, H. Baueeman, and A. Geikie. — 'A Descrip- 



tive Catalogue of the Bock Specimens in the Museum of Practical Geology.' 

 Second edition (I860), p. 296. 



2. W. Whitakee.— ' On the " Chalk Bock," the topmost hed of the Lower Chalk, 



in Berkshire, Oxfordshire, Buckinghamshire, etc' Quart. Journ. Geol. Soc. 

 vol. xvii. (1861) p. 166. 



3. E. Hull and W. Whitakee. — ' The Geology of Parts of Oxfordshire and Berk- 



shire ' (1861), p. 20. Mem. Geol. Survey. 



4. W. Whitakee. — ' The Geology of Pai-ts of Middlesex, Hertfordshire, Bucking- 



hamshire, Berkshire, and Surrey ' (1864), pp. 5-8. Mem. Geol. Survey. 

 6. W. Whitakee. — ' On the Chalk of Buckinghamshire and on the Totternhoe 

 Stone.' Quart. Journ. Geol. Soc. vol. xxi. (1865) p. 398. 



