494 MESSES. WHITAKER AND JUKES-BROWNE ON [Aug. 1 894, 



had been prepared from the Eichmond samples, and on examining 

 these we found that the Culford limestones bore a very close 

 resemblance to the highest part of the Richmond series, i. e. the 

 top part of that classed as Neocomian by Prof. Judd. 



Not only is the general structure similar, but the same varieties 

 of stone occur : thus one sample from Richmond, at 1141^ feet, is 

 a grey stone without any brown grains, but consisting of broken 

 shell-fragments (echinoid and mollusean), with some cyprid-cases, 

 a few foraminifera, and a few scattered grains of quartz, embedded 

 in a dull calcareous matrix. This is similar to the grey limestones 

 of Culford. Another slide (marked from 1141 1, but probably a 

 little lower than the first) and one fiom 1144 feet show similar 

 enclosures, but the fragments are more rolled and scattered, many 

 are stained by a dark brown material, some partially and some 

 completely, and the matrix is clear crystalline calcite. These 

 resemble the rock with brown grains at Culford, in which, however, 

 the matrix is dirtier and the fragments rather smaller. Both have 

 very little quartz, and cannot be called sandy rocks. 



Such close resemblances in structure between two rocks occupying 

 the same stratigraphic position are certainly suggestive of identity 

 in age, especially as we know of no other rock which has a similar 

 structure. 



Of the uppermost portion of this limestone at Richmond Prof. Judd 

 remarks that " the rock very closely resembles, both macroscopically 

 and microscopically, certain varieties of the Xentish Rag." It is 

 true that the calcareous sandstones which occur in the Hythe Beds 

 between Hythe and Seveuoaks, and are known as Kentish Rag, vary 

 considerably in microscopic structure ; but, so far as we can judge 

 from the slides that we have examined, they seldom consist very 

 largely of shell- fragments. Sometimes they contain much quartz 

 and glauconite, sometimes very little. At Hythe the prevalent kind 

 of limestone seems to be one containing a large number of sponge- 

 spicules, with a few shell-fragments, a fair amount of green 

 glauconite, and comparatively little quartz. Except in the small 

 amount of quartz, this will not compare with the Culford rock. 



There is, however, much resemblance between the finer-grained 

 stone at Culford and a calcareous stone in the Hythe Beds at Til- 

 burstow Hill, near Godstone. There is a specimen of this in the 

 Museum of Practical Geology (Case E, 2076), and a slide was cut 

 from it for our inspection. The matrix is crystalline granular 

 calcite, and through this are scattered shell-fragments, sponge- 

 spicules, glauconite-grains and a few quartz-grains, both of these 

 being small. A few of the shell-fragments show echinodermal 

 structure, and there are several foraminifera, including a Textalaria. 



We have also compared the Richmond and Culford rocks with 

 three slides of Bargate Stone from localities near Godalming and 

 Guildford, and find a considerable degree of resemblance between 

 them. These samples of Bargate Stone consist mainly of shell-frag- 

 ments, among which bits of echinoid shell and spines are abundant, 

 set in a matrix of clear crystalline calcite; the amount of quartz 



