G. E. Grimes — Radiohrians in Chalk. 347 



two concentric spherical lattice shells (outer cortical and inner 

 medullary). As the lattice shells are now more or less infilled with 

 foreign material the lattice structure of the inner one is not always 

 visible. One of the best defined of these forms is represented in 

 Fig. 1, and as it appears to be new I propose to name it Garposphcera 

 Neocomiensis. The diameter of the cortical shell is -07 mm. (Fig. 1), 

 and the breadth of the medullary shell -032 mm. There appear to 

 have been originally eight or nine rays connecting the two shells. 

 The lattice mesh of both shells is irregularly polygonal. 



Haliomma species ? Fig. 2.— As seen in section the boundary 

 is irregularly circular, with numerous cusps, probably the bases of 

 spines. The inner border, as seen in figure, was probably the 

 boundary of the inner test. In the central area there are some 

 faint indications of lattice structure. This organism was found on 

 the thin edge of the rock section. Diameter -139 mm. 



The second occurrence of Radiolaria is in the Upper Greensand 

 at Colley Farm, Reigate. The section at present visible in the pits 

 is, in descending order — 



Chalk Marl. ft. in. 



Greenish Sand (equivalent to chloritic marl) .... 76 



Chert 6 



Soft Hearthstone 6 



Chert 6 



Hard Hearthstone 5 to 6 feet. 



Fire and Building Stone 60 



The Radiolaria were found both in the Upper and Lower beds of 

 Hearthstone. These beds in thin sections under the microscope 

 exhibit a similar composition to that of the Fuller's Earth rock 

 previously described, but the constituent fragments are smaller in 

 size. The beds are made up of broken sponge spicules, grains of 

 quartz, glauconite grains and casts, Foraminifera mostly infilled with 

 glauconite and flakes of mica. The globular form of silica is, 

 however, more developed than in the Fuller's Earth rock, and when 

 sections are examined with the ^ inch objective the globules are 

 seen to make up a large proportion of the slide. The Radiolaria in 

 these beds are not so well preserved as those in the Fuller's Earth, 

 rock, but they appear to belong to the same genus — Carpospliara. 



Fig. 3 represents one of these fiom the Upper Hearthstone ; the 

 diameter of the cortical shell is -145 mm. Fig. 4 represents a form 

 from the Lower Hearthstone ; the diameter of the cortical shell 

 is •! mm. 



I have to thank Mr. F. Chapman, F.R.M.S., f(n- advice and 

 assistance in the preparation of this paper, and for the excellent 

 figures which accompany it. I wish also to thank Dr. G. J. Hinde, 

 F.G.S., for examining the specimens and advising me on some 

 diflScult points ; also Professor Judd, F.R S., for kind advice and 

 facilities for making Some of the preparations. 



