BRACKLESHAM BEDS. 115 



London Clav I ^^^^ overgrown - - - - 1 1 



^ L Sand (Basement Bed of the London Clay) - 6 



Reading Beds Red and mottled clay • - - 92 

 Chalk, nearly vertical. 



In the shelly bed 160 feet {"rom the Chalk the following species 

 (determined by Messrs. Sharman and Newton) were obtained, 

 mostly by J. Rhodes (the fossil- collector of the Geological 

 Survey). 



B Area biangula. Lam. B Natica acuta. Sow. 



L B Cardita planicosta, Lam. B obovata, Sow. 



L B Corbula striata, Lam. B Pleurotoma dentata. Lam. 



B Cytherea lucida, Lam. L B denticula. Bast. 



L B suberycinoides, DesA. L teretrium? Edw. 



B trigonula, Desk. B Pseudoliva obtusa, Sow. 



B Rosteliaria rimosa, Sow. 



B Ancillaria buccinoides. Lam. Solarium, sp. 



B Conus deperditus, Brong. L B Turritella imbricataria, Lam. 



B Fusus longaevus, Lam. B sulcata. Lam. 



L B pyrus. Brander. Voluta, sp. (fragment). 



Myliobatis (fragment). 



The species marked B (including the whole of the forms 

 determined, with one doubtful exception) are well-known Brackle- 

 sham shells ; those marked L are found in the London Clay. 

 The Pleurotoma teretrium (a somewhat doubtful determination) 

 is the only species elsewhere confined to the London Clay. 



Between Ashey and Alum Bay no good sections of the Brackles- 

 hara Beds occur. A\ hen the strata are again met with, in Alum 

 Bay, their character is so entirely altered that it becomes impossible 

 to correlate the minor divisions, or, as already stated, to be certain 

 whether the upper and lower boundaries have been taken in the 

 same place at opposite ends of the Island. 



In the following section the upper limit of the Bracklesham 

 Beds has been taken at the point fixed, on palaeontological 

 grounds, by Mr. Fisher, instead of at the pebble bed originally 

 adopted as the junction in the first edition of this Memoir. This 

 increases the thickness of the Bracklesham Beds at this point 

 by 44 feet, making the total 155 feet instead of 111 feet. 

 The details of the fossiliferous beds above the conglomerate are 

 taken from Mr. Fisher's paper,* those of the lower beds are from 

 the first edition of this Memoir. 



Section of the Bracklesham Beds in Alum Bay. 



Ft. In. 

 Barton Clay. — Dark sandy clay with fossils (principally small 



bivalves). 

 Dark sandy clay - - - - - -ISG 



Indurated, dark-greenish, sandy clay, with impressions 



of fossils - - - - - - -10 



Fusus undosus ? Cytherea lucida. 



Murex asper. suberycinoides. 



Pyrula nexilis. Sanguinolaria HoUowaysii. 



Turritella imbricataria. Modiola, sp. 



Natica ambulacrum. Tellina plagia. 



* Quart. Joum. Geol, Sac, vol. xviii. p. 85. (1862.) 



H 2 



