346 PKOF. S. H. KETNOLDS AND DE. A. VAUGHAN ON [Aug. I9II,. 



typical china-stone of the overlying strata in containing numerous 

 foraminifera. 



S 2 (b). This division includes the limestone with chert-bands 

 occupying the middle third of the hillside between Quarries 1 

 and 2. 



These limestones are, as a rule, characterized by their highly 

 foraminiferal and often oolitic nature, but they include in the 

 upper part some bands of very fine-grained horny limestone of 

 china-stone type. At (20) — see PI. XXVIII, fig. 3 — occurs 

 an interesting rock-type. It consists largely of very irregular, 

 commonly well-rounded fragments of compact horny limestone, 

 frequently enclosing a foraminifer or a bit of a crinoidal ossicle, the 

 whole being united by a cement of crystalline calcite. In this 

 case, after the penecontemporaneous brecciation of the limestone, 

 the fragments were rounded, either by rolling or by solution, before 

 being united in the crystalline matrix. All these various pro- 

 cesses were probably quite rapidly carried out. 



The most marked feature of the rocks of this horizon is, however,, 

 afforded by the cherts, of which there are some six bands frequently 

 associated with bands of Lithostrotion. In colour these cherts are 

 generally pale pinkish-grey. A section cut from one at (17) was 

 kindly examined by Dr. Gr. J. Hinde, who confirmed the attribu- 

 tion of certain rod-like fragments to sponge-spicules, suggesting 

 that they were parts of the anchoring spicules of hexactinellid 

 sponges. With regard to certain round bodies which it was 

 suggested were radiolaria, Dr. Hinde writes as follows : — 



' The round bodies are small siliceous spheres with a smooth exterior and a 

 relatively thick wall, enclosing a central area which is now infilled with silica 

 of a different tint from that of the wall. The wall is traversed by numerous 

 radiating straight spines or spokes, which connect the inner area with the 

 outer surface of the sphere. These seem to me to be really minute pores or 

 canals now infilled with silica of the same tint as that of the central area of 

 the sphere. The spheres are from 01 mm. to 0*13 mm. in diameter, and 

 their walls from 0*025 mm. to 0*04 mm. in thickness. Assuming that these 

 bodies were originally siliceous, which seems to have been the case, I should 

 judge that they are radiolaria.' 



Bands full of papilionaceous Chonetes also occur. 



S 2 (a). This band includes (1) the ill-exposed limestone between 

 the top of Quarry 2 and the lowest chert-bands, and (2) the lime- 

 stone exposed in Quarry 2 as far as the prominent rib of rock which 

 is taken as marking the base of S 2 . The upper ill-exposed beds 

 consist in the main of grey foraminiferal and not markedly oolitic 

 limestone, but near the edge of the quarry an oolitic character 

 begins to be apparent. 



At (89) a brown bed occurs which is in the main a finely oolitic 

 limestone, the grains being often formed round foraminifers. 

 Between the grains is crystalline calcite ; and numerous, minute, 

 brown patches of associated dolomite and chalybite crystals are' 

 seen in thin sections to be the cause of the coloration. 



