US ON THE LONDON CLAY FORMATION 



Upon one of the bouldered flints, firmly embedded in the 

 marly sand, I found the most interesting of the valuable series 

 of fossils which I had the good fortune to obtain during this 

 excursion, namely, a fine specimen of Astrea, built upon the 

 upper and exposed surface of a flint. The base of the coral 

 is three and a quarter inches long and two and a quarter wide, 

 and closely embraces and spreads over the rounded edge of 

 the smooth stone. No part of the coral appears to have suf- 

 fered firom attrition : it is three and a half inches in height 

 from the base to its upper surface, from which a considerable 

 portion has been broken off", and the fractured surface presents 

 every appearance of having suffered no other injury than that 

 arising from the action of the water since it was exposed. I 

 have carefully examined, with a high microscopic power, thin 

 sections of the stone on which this interesting coral is built, 

 and can safely assert that it is truly a chalk-flint, as it exhi- 

 bits the characteristic organic structure of the Kentish chalk- 

 flints, and abounds with the well-known forms of the foramen- 

 iferous shells of the chalk. On the following day I obtained 

 fi:om one of the coast-guard, a second but smaller specimen 

 of the same coral, which had been picked up close to the spot 

 where mine was procured. This has been drawn by Mr. J. 

 DeC. Sowerby, and engraved to accompany the present paper. 



Astrea is completely a tropical genus ; but when we consi- 

 der the many other tropical forms occurring in the same for- 

 mation, such as those abounding among the fruits, the remains 

 of saurians and fresh- water turtles, and also that Astrea has 

 been found in the lower beds of the calcaire grossier, we shall 

 not be surprised at its occurrence in beds which, according 

 to the description of Mr. Webster, are so closely allied to 

 those of the calcaire grossier of Liancourt, both as regards 

 their mineral character and their fossil contents. 



Near the Thorny coast-guard station Cerithium Cornuco- 

 pi<B and giganteum, Turritella sulcifera [Melania sulcata of 

 Sowerby), Tur. terehellata and multisulcata^ are found, al- 

 though I could not ascertain the beds from which they come, 

 but their position is probably lower in the series than those 

 which occur to the westward of Brackelsham barn. Sower- 

 by, in the description of Melania sulcata in the ^ Mineral 

 Conchology,' states that at Stubbington, where the specimen 

 figured was found, " the cliff" is twenty or thirty feet high, 

 composed of sand and gravel, more or less mixed with blue 

 mud, and frequently irregular patches of sand. At the base of 

 this is a stratum, not more than two feet thick, of blue clay 

 or mud, in which the shells are found." 



