296 Dr. FiTTON on the Strata below the Chalk. 



The course of the upper chalk is prominent on the north of east, from 

 Dunstable through Hitchin and Baldock, to Royston Down in Cambridge- 

 shirCj which is 464 feet above the sea : but the boundary between the lower 

 chalk and the strata next below is not distinctly indicated by the external 

 features of the country. The change occurs on the main road from London 

 to Bedford^ between Hitchin and Sheffbrd, about the 37th milestone : and 

 there the difference in the elevation and general appearance of the ground 

 is very slight ; in part from the very gradual rise of the strata, but chiefly 

 from the general diffusion of a coating of transported materials, which con- 

 ceals them. 



(155.) List of Fossils from the Beds between the Chalk and the Oxford 

 Oolite, in part of Oxfordshire, Buckinghamshire, and Bedford- 

 shire. 



[^Superficial Gravel.] 



Ammonites (fragments). Chelsey, near Leighton, Bedf. (From the Gault?.) 



Belemnites minimus'^, (fragments). Stone Lane, north of Heath, Bedf. 



B . Gravel-pit north-east of Stevvliley, Bucks: with fragments of chalk; 



top of the high grounds, Brigginton, &c., near Leighton, Bedf. 

 Grj/phaea dilatata (much worn.) Gravel-pit north-east of Stewkley, Bucks. 



G- (fragments). Stone Lane, north of Heath, near Leighton, Bedfordshire. 



G ohliqua (much worn.) Gravel-pit north-east of Stewkley. 



Ostrea deltoidea (fragments). Stone Lane, north of Heath, Bedf. 



Serpula. Gravel-pit, north-east of Stewkley. 



Terehratula. In rolled piece of sandy limestone. Gravel-pit north-east of Stewkley. 



Spongia} Flint, enveloping Sponges? : worn. (No doubt from the upper chalk.) 



Gravel-pit north-east of Stewkley. 



\_Lorver Chalk and Chalk Marl.'] 

 Ammonites lautus. In pale marly clay (chalk marl). Tetsworth, Oxf. 

 Terehratula semiglobosa. Tetsworth, Oxfordshire : in flint. 



[Upper Green-sand.] 



Inoceramus. Between Tetsworth and Thame, Oxf, ; with Vermetus, in bluish grey 



tirestone. 

 Mi/tilus (new species ?). Between Tetsworth and Thame : in soft gritty firestone. 

 Siphonia. Impressions of stems. Totternhoe, Bedf. 

 Vermetus. Between Tetsworth and Thame : with Inoceramus; in bluish grey stone. 



[Gault.'] 

 Ammonites decipiens. Compton, Bedf. Mr. Goodhall. 

 Avicula. Compton, Bedf Mr. Goodhall. 

 Crenatula. Compton, Bedf Mr. Goodhall. 



