csalk with belemnitella quadrata. 357 



bands below tbe base of the Tertiary strata. The following mea- 

 surements were made bv Mr. Lodge, and kindly supplied to me by 

 Mr. Grenfell.— May, 1891. J 



ft. in. 



Reading fClay 7 



Beds. I Green sand with green -coated flints 2 (i 



fWliite chalk 18 



I Brownish white chalk 2 



Upper j Brown chalk [upper phosphatic band] 11 



Chalk. ) Hard white chalk 12 



I Soft b-own chalk [lower phodphatic band] 4 



l^Very hard white chalk 



56 () 



The specimens from which the folio wins: notes have been drawn 

 up were collected from the brown bands of the above section. Both 

 bands owe their colour to a multitude of brown grains, and pass up 

 gradually into a rock less rich in brown g^rains, and of a pale brown 

 or greyish tinge. The chalk is irregularly bedded, perhaps current- 

 bedded, and traversed by irregular joints, so as to break readily up 

 into blocks, which crumble into a rounded form and finally into 

 powder. Its friability forms a marked feature, and is duo to the 

 softness of a white chalky paste in which the brown grains are 

 embedded. Under the microscope these grains are seen to be almost 

 entirely of organic origin, foraminifera, the prisms of Inoceramus- 

 shells, and small oval pellets forming the bulk. The following list 

 of foraminifera has been kindly prepared for me by Prof. T. llupcrb 

 Jones, r.li.S. : — 



List of Foraminifera in Chalk from Taplow. 



Textidaria (/lohosa, Ehrenberg (common). 



„ sp., angular edges (1 specimen). 



„ sp., square edges (a fragment). 



Spiroplecta hiformis^ P. & J. (1 specimen). 

 Bolivina textularoides^ Reuss (1 specimen). 

 Nodosaria radicida^ Linn. sp. (1 specimen). 

 Cristellaria rottdata, Lamarck (common). 



„ cidtrata, Montfort (1 specimen). 



Planorhidlna ammonoides, Reuss (common). 

 Rotalia Beccarii, Linn. (1 specimen. Very rare in the Chalk). 

 Glohigerina cretacea^ D'Orb. (common). 



„ linnreana^ D'Orb. (a fragment). 



„ hidloides, (1 specimen). 



Below both bands of brown chalk there occur some few feet of 

 white chalk, traversed by cavities and tubes of all shapes and sizes 

 up to an inch in diameter, and filled with the brown chalk. The top 

 of this piped chalk is in both cases hard, crystalline, and of a nodular 

 structure, so as to form a clearly marked floor to the soft brown 

 ch^ilk. 



Finding that 97*7 per cent, of the brown chalk dissolved in cold 



