WEALDEN FORMATION. 315 
Fig. 289. Fig. 290. 
Fig. 289. a, b. Tooth of Iguanodon Mantelli. Fig. 290. a. Partially worn tooth of 
young individual of the same. b. Crown of tooth in adult worn down. (Mantell.) 
of having been chipped off, but never, like the fossil teeth of 
the Iguanodon, have a flat ground surface (see Fig. 290, b) 
resembling the grinders of herbivorous mammalia. Dr. Man¬ 
tell computes that the teeth and bones of this species which 
passed under his examination during twenty years must 
have belonged to no less than seventy-one distinct individ¬ 
uals, varying in age and magnitude from the reptile just 
burst from the egg, to one of which the femur measured 
twenty-four inches 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 in¬ 
dividuals had been found, that a solitary example of part of 
a jaw-bone was obtained. Soon afterwards remains both of 
the upper and lower jaw were met with in the Hastings beds 
in Tilgate Forest, near Cuckfleld. In the same sands at Has¬ 
tings, Mr. Beckles found large tridactyle impressions which 
it is conjectured were made by the hind feet of 
this animal, on which it is ascertained that there 
were only three well-developed toes. 
Occasionally bands of limestone, called Sussex 
Marble, occur in the Weald Clay, almost entirely 
composed of a species of Paludina^ closely resem¬ 
bling the common P. vivipara of English rivers. 
Shells of the Cypris^ a genus of Crustaceans before 
mentioned (p. 57) as abounding in lakes and ponds, 
are also plentifully scattered through the clays of the Weal- 
Fig. 291. 
Cypris spini- 
gera, Fitton. 
