Dr. FiTTON on the Strata below the Chalk. ^ 302 



Pleurofomaria reticulata {Trochus,M.C. ) Headington ; Oxf. 

 Serpula tetragona. Clophill, Bedf., Mr. Goodhall. 



S tricarinata ?. Roadside between Aylesbury and Whitchurch. " In stiff clay, 



" about two miles N.N. west of Leighton." Mr. W. Mathews. 



Fishes. C/«m<sra Egertoni : (Buckland, Proc. of Geol. Soc. vol. ii. p. 206. ; and 

 Lond. and Edinb. Phil. Mag. (1836), vol. viii. p. 4—7.) Shotover-hill, Oxf. 

 Psarnmodus reticulatus : (Agassiz ; in Egerton's Catalogue of Fossils); Shot- 

 over-hill, Oxfordshire. 



Reptiles. Bone of a Saurian. Clay-pits south-west of Stewkley : part of a flat bone. 



Plesiosaurus ; Vertebra;. Headington Quarry, Oxf. 



Coprolite ; or coproid masses of phosphate of lime. Beneath Whitchurch. Clay- 

 pits south-west of Stewkley : one specimen occupying the cavity of an Am- 

 monite. 



lOxford Oolite.'] 

 Melania Heddingtonensis. Wheatley, Oxf. : cast of part of interior. 

 Ostrea} Thornborough, Oxf. Wheatley; in compact, blue, sparry oolite. 

 Pholadomi/a deltoidea. Headington (Coral rag). 

 Spongia ?. Wheatley, Oxf : in sandy stone. 

 Terebratula tetrahedra ? Thornborough, Oxf. ; and Wheatley. 



Cambbidgeshire*. 

 (156.) In this county, as in Bedfordshire, the Wealden and Portland groups 

 are wanting; and the strata, rising with a very slight inclination from the 

 south of east, and thinning off near their outcrop, are frequently cut through 

 by denudation, so that distant outliers, especially of the lower green-sand, are 

 frequent. Mr. M'Lauchlan, who was engaged in the Ordnance Survey of this 

 part of England, remarks, that the summits of the chalk decline rapidly in 



* I am indebted to my friend Professor Sedgwick for the greater part of the following infor- 

 mation respecting Cambridgeshire. The only publications connected with the geology of the 

 county, are a paper by Professor Hailstone, Geological Transactions, 1st Series, vol, iii. p. 243, &c. ; 

 a short paper on the Northern division of Cambridgeshire, by Mr. Lunn, (1818), — Geol. Trans., 

 1st Series, vol. v. p. 114, &c. ; an account of some verbal communications made to the Cambridge 

 Philosophical Society, London Philosophical Magazine, (1835,) vol. vi. p. 74 ; and the report of 

 a field Lecture by Professor Sedgwick, which appeared in the Cambridge Chronicle of the 10th 

 of April 1835. 



Huntingdonshire I have passed over, not having myself examined that county ; and I am not 

 acquainted with any publication specifically relating to it, except Mr. Smith's county map. A 

 small space at the south-eastern verge of the county, on the confines of Bedfordsiiire, is occupied 

 by the Lower green-sand ; but all the tract adjoining Cambridgeshire is assigned by Smith to the 

 Oak-tree clay, a term which I believe denotes, in this case, the Kimmeridge clay. The strata 

 thereabouts are much obscured by transported matter. 



VOL. IV. SECOND SERIES. 2 R 



