214 COMPARISONS OF THE CRAG AND FALUNS. [Oh. XIV. 



are in perfect accordance with the fact of the smaller proportion of testacea 

 of recent species found in the faluns. 



Out of 290 species of shells, collected by myself in 1840 at Pontlevoy, 

 Louans, Bossee, and other villages twenty miles south of Tours ; and at 

 Savigne, about fifteen miles northwest of that place, seventy-two only 

 could be identified with recent species, which is in the proportion of 

 twenty-five per cent. A large number of the 290 species are common to 

 all the localities, those peculiar to each not being more numerous than we 

 might expect to find in different bays of the same sea. 



The total number of testaceous mollusca from the faluns, in my pos- 

 session, is 302 ; of which forty-five only were found by Mr. Wood to be 

 common to the Suffolk Crag. The number of corals, including bryozoa 

 and zoantharia, obtained by me at Doue, and other localities before ad- 

 verted to, amounts to forty-three, as determined by Mr. Lonsdale, of which 

 seven (one of them a zoantharian) agree specifically with those of the Suf- 

 folk Crag. Only one has, as yet, been identified with a living species. 

 But it is difficult, notwithstanding the advances recently made by MM. 

 Dana, Milne Edwards, Haime, and Lonsdale, to institute a satisfactory 

 comparison between recent and fossil zoantharia and bryozoa. Some of the 

 genera occurring fossil in Touraine, as the Astrea. } Dmdrophyllia, Lunu- 

 lites, have not been found in European seas north of the Mediterranean ; 

 nevertheless the zoantharia of the faluns do not seem to indicate on the 

 whole so warm a climate as would be inferred from the shells. 



It was stated that, on comparing about 300 species of Touraine shells 

 with about 450 from the Suffolk Crag, forty-five only were found to be 

 common to both, which is in the proportion of only fifteen per cent. 

 The same small amount of agreement is found in the corals also. I for- 

 merly endeavored to reconcile this marked difference in species with the 

 supposed coexistence of the two faunas, by imagining them to have sever- 

 ally belonged to distinct zoological provinces or two seas, the one opening 

 to the north, and the other to the south, with a barrier of land between 

 them, like the Isthmus of Suez, separating the Red Sea and the Medi- 

 terranean. But I now abandon that idea for several reasons ; among 

 others, because I succeeded in 1841 in tracing the Crag fauna southwards 

 in Normandy to within seventy miles of the Falunian type, near Dinan, 

 yet found that both assemblages of fossils retained their distinctive char- 

 acters, showing no signs of any blending of species or transition of cli- 

 mate. 



On a comparison of 280 Mediterranean shells with 600 British species, 

 made for me by an experienced conchologist in 1841, 160 were found to 

 be common to both collections, which is in the proportion of fifty-seven 

 per cent., a fourfold greater specific resemblance than between the seas of 

 the crag and the faluns, notwithstanding the greater geographical dis- 

 tance between England and the Mediterranean than between Suffolk and 

 the Loire. The principal grounds, however, for referring the English crag 

 to the Older Pliocene and the French faluns to the Miocene epochs, con- 

 sist in the predominance of fossil shells in the British strata identifiable 



