402 RETROSPECT OF THE OOLITIC SYSTEM. CHAP. 



AFFINITIES OF OOLITIC LIM^E. 



hians. 

 expansa. 



Hoperi. 



Faringdonensis. 



I 

 'So 



Three, or perhaps four, distinguishable fossil races are included 

 in this Table, originating in the sharply-ridged Lima pectinoides, 

 the smoothly-polished L. gigantea, the ribbed L. Hermanni, and 

 the tubercled L. proboscidea. They are frequent in the lias and 

 oolites, and the recent species, though not very numerous, present 

 structural characters which bring them into relationship with the 

 older members of the family. Original differences have had long 

 periods of successive representation. 



