54 MICROSCOPICAL OBJECTS FOUND 



of chalk and limestone, I would direct attention 

 to a few other recent and tertiary deposits, which 

 help to illustrate the subject, and show some of 

 the links which connect the existing with the 

 more ancient phenomena. 



On most of our English coasts, extensive 

 deposits occur, which are largely composed of 

 comminuted shells and corals ; whilst various 

 forms of unbroken Foraminifera and some Cy- 

 therse are scattered through the pulverised mass. 

 The two latter generally constitute but a small 

 proportion of the calcareous matter, though in 

 some cases they are much more numerous. The 

 whole is usually mixed up with different inorganic 

 substances, as sand, carbon, aluminous and mica- 

 ceous earths, varying according to the locality 

 from which they are obtained. On the Yorkshire 

 coast the first two prevail. On those of Wales, 

 especially near Tenby, the specimens I have 

 examined contained a larger proportion of the 

 latter, derived from the primary schistose rocks 

 of the neighbourhood. These recent accumula- 

 tions have been known to most conchologists 

 during the last two centuries. On a detailed 

 examination of the genera of Foraminifera found 

 on our coasts, we shall subsequently see that they 



