34 MR. A. M. DAVIES ON THE KIMERIDGE CLAY [Feb. I907, 



may also be shown by the sudden increase in the proportion of 

 selenite beyond a certain circle. It would seem that the ferrous 

 sulphate penetrated the guards along certain radial and concentric 

 lines of weakness. 



No other recognizable fossils are, as a rule, selenitized. I have 

 noted one case of Ostrea deltoidea thus altered, but in general the 

 oysters are untouched. 



At various times, diggings have been made below the floor of the 

 pit, for chimney-foundations and a reservoir. One of these, nearly 

 6 feet deep, I was able to examine. The greater part of the clay 

 exposed was of similar character to that just described, full of small 

 selenite-crystals ; but one band in it (of the precise level of which I 

 have no note) was of a light-blue colour, free from selenite, and has 

 yielded numerous microscopic fossils. Larger fossils also occurred, 

 some phosphatized. At the bottom of this digging was a layer of 

 argillaceous limestone ; and although I did not obtain any fossils 

 from this, some were thrown out from probably the same limestone 

 in a deeper digging. The full list of fossils from below the floor of 

 the pit is as follows, those marked L being from the limestone : — 



Perisphinctes plicatilis (Sow.). 

 Perisphinctes decipiens (Sow.) (L). 

 Perisphinctes sp. 

 Cardioceras cordatum (Sow.). 



Trigonia Juddiana, Lye. (L). 

 Area sp. 



Pentacrinus (small ossicle). 

 Crinoid-ossicle (minute). 

 Echinoid-spine (minute). 



Cytheridea (1). 



Cristellaria. 

 Pulvinulina (?). 



The most fossiliferous rock in the brickfield yet remains to be 

 described, as, strange to say, its exact horizon is uncertain. This 

 consists of a series of rounded masses or ' doggers ' of an impure 

 limestone, the biggest of which are nearly 2 feet in diameter and 

 6 inches thick. These were all dug up prior to my first visit in 

 1899, and Mr. Uff informs me that none have been met with during 

 the last seven years. They can only, therefore, have come from 

 the selenitic clay, or from the lower part of the overlying grey clay, 

 as those were alone exposed in 1899 ; and, as they are sometimes 

 selenitic at the surface, they more probably come from the selenitic 

 cla}'. It is remarkable that they should have been so abundant 

 near the natural surface of the ground, and yet be wanting farther 

 into the hill. 



The stone is extremely tough, and while such bivalves as Cyprina 

 and Astarte easily come out when it is broken, such fossils as 

 belemnites and oysters are usually inextricable. Fortunately, I 

 have lately found some of the doggers that have been softened by 

 long weathering, and from them have extracted fossils that can be 

 seen in, but not removed from, the ordinary stone. By far the most 

 abundant species are Serpula tetragona, Sow., and a little Cyprina. 

 The following is the complete list of fossils identified : — 



