348 



FOSSILS OF THE 



[Ch. XVIII. 



incL.es in circumference. Yet, notwithstanding that the teeth were more 

 numerous than any other bones, it is remarkable that it was not until 

 the relics of all these individuals had been found, that a solitary ex- 

 ample of part of a jawbone was obtained. More recently remains 

 both of the upper and the lower jaw have been met with in the Hast- 

 ings beds in Tilgate Forest. Their size was somewhat greater than, 

 had been anticipated, and Dr. Mantell, who does riot agree with Pro- 

 fessor Owen that the tail was short, estimates the probable length of 

 some of these saurians at between 50 and 60 feet. The largest femur 

 yet found measures 4 feet 8 inches in length, the circumference of 

 the shaft being 25 inches, and if measured round the condyles, 42 

 inches. 



Occasionally bands of limestone, called Sussex Marble, occur in the 

 Weald Clay, almost entirely composed of a species of Paludina, closely 

 resembling the common P. mvipara of English rivers. 



Shells of the Cypris, a genus of Crustaceans before mentioned (p. 

 31) as abounding in lakes and ponds, are also plentifully scattered 

 through the clays of the Wealden, sometimes producing, like plates of 

 mica, a thin lamination (see fig. 342). Similar cypris-b earing marls 

 are found in the lacustrine tertiary beds of Auvergne (see above 

 p. 224). 



Fig. 340. 



Fie. 341. 



Cypris Valdensis, Fitton. 

 (<7. fdba, Min. Cob. 485.) 



Weald clay with Oyprides. 



Hastings Sands. 



This lower division of the Wealden consists of sand, sandstone, 

 calciferous grit, clay, and shale ; the argillaceous strata, notwithstand- 

 ing the name, predominating somewhat over the arenaceous, as will 

 be seen by reference to the following section, drawn up by Messrs. Drew 

 and Foster, of the Government Survey of Great Britain : 



Hastings Sand. 



Names of Subordinate 

 Formations. 



Tunbridge Wells 

 Sand, 



Wadhurst Clay, 

 Ashdown Sand, 

 Ashburnham Beds, - 



Mineral Composition 

 of the Strata. 



Sandstone and loam, - 



Thickness 

 in Feet. 



Blue and brown shale and clay 

 with a little calc-grit, 



Hard sand with some beds of 

 cale-grit, - - - 



Mottled white and red clay with 

 some sandstone, 



150 



100 

 160 

 330 



