THE LIAS. 127 



moured saurian is found, which in many ways re- 

 sembles the Iguanodon oi a iuter period, and is 

 the type of a 

 family with ver- 

 tically serrated 

 teeth aamed 

 Scelidosauridae. 



The {< 

 which arc r 



abundant ai 

 multitude < >f ex- 

 es of 

 and 



t< >- 

 gether with an Fig. 20.— Gtyphxaincurvm: Lias, 



with an 

 involute mode of growth, known as the genus 



Gr\ -nail of the 1 logger 



fishermen. But with - tions the great 



multitude of the I [ ;< -ue- 



ra. A in- >ng wh - Lima t Pecten % 



I icula y Afodiola % Tri- 



\tula : and the V \\\ shells Litto- 



rina and Pleun abundant. Speciesof 



the genus Amm give nam ib-divisions 



es of the l . s ich as t 'ar- 



dinia and Hippopodium are only found in the Lias. 

 There is no sharp separation to be 



LWn between the Lower and Middle Lias. The 

 two beds are conformable to each other, although 

 lish them, and there is some 

 difference in their mineral character. The Mid- 

 dle Lias comprises the marl stone, which forms 

 an escarpment in the middle of England; and it 

 also includes the ironstone series, which is well 

 developed in the Cleveland district of Yorkshire, 



