CRAG OF NORFOLK AND SUFFOLK. 355 



minority of recent shells ; and the remaining deposits to the 

 pliocene, or modern, from 7rAo>j/, major, and KCUVOS, recens, 

 showing that these deposits contain a majority of recent 

 shells. He subdivided this latter class again as follows : 

 the beds which contained fifty per cent, of existing shells 

 were termed older pliocene, while those which presented 

 ninety in a hundred of living forms were named newer 

 pliocene. The student will best understand the whole as 

 signifying ancient tertiary, middle tertiary, and modern ter- 

 tiary; subdividing the latter into early modern tertiary, and 

 later modern tertiary. 



Alcide D'Orbigny divides the tertiary period into four 

 stages, each characterised by a special fauna ; which he has 

 named Sub-apennine, Falunian, Parisian, and Suessonian; 

 these four stages contain 6,040 species of mollusca and 

 radiata, the distribution of which is shown in this table : 



o_, . _ __ Number of species Number of species Total Number 



of Mollusca. of Radiata. of species. 



Sub-apennine . * - 444 162 606"! 



Falunian . . . 2,903 160 3 > 063 Unin 



Parisian . . . 1,478 199 1,677 p U4 ' 



Suessonian. . > 562 132 694J 



GrEO GRAPHICAL DISTRIBUTION OF THE TERTIARY STRATA. 



They prevail extensively in this country, but are more 

 largely developed on the continent of Europe, occurring in 

 France, Italy, Sicily, Germany, and in Asia, Africa, America, 

 and Australia. 



FIG. 252. VolMa Lamberti, Red crag. FIG. 253. Fusus contrarius, Red crag. 



A A 2 



