on the Organic Cojnposition of Chalk and Chalk Marl. 389 



Living. 



51. Peridinium pyropho- 1 3^,^; ^^^^ j^j^j 

 rum J 



52. Striatella arcuata 



r Gulfof Flensburg, Break- 



53. Synedra ulna ■ 



54. Tessella Catena . . 



55. Triceratium Favus , 



ers near Gothenburg. 

 ' Baltic near Wismar, Ber- 

 lin fresh waters, North 



of Germany, Denmark, 



Scotland, Holland, the }> C M. Oran 



Ural, and perhaps Isle 



of France, and Masca- 



rene Isles 



J Breakers near Gothen- 



[ burg and Berlin waters. 



North Sea, Cuxhaven . . 



Fossil. 

 Flints of the W. C. near 

 Gravesend, and Flints 

 of the plain of North 

 Germany near Delitzsch. 



C. M. Oran. 



C. M. Caltasinetta. 



56. Xanthidium furcatum Berlin 



57. 



hirsutum 



Peat waters near Berlin. 



C. ]M. Greece. 



Flints of W. C. Graves- 

 end, and Flints of 

 Delitzsch. 



Flints of W. C. Graves- 

 end, and Flints of 

 Delitzsch. 



Of these fifty-seven species, thirty belong to the geolo- 

 gically acknowledged chalk and its Sicilian marls. The re- 

 mainder from Oran, Greece (probably Egina), and Zante, 

 though perhaps from beds not equally well defined by relative 

 position as chalk marls, yet occurring, as they do, with nume- 

 rous decided calcareous and siliceous animals of the chalk, — 

 the geological relations of these species may also be considered 

 as firmly established. 



These new discoveries naturally lead to the conclusion that 

 we have now no very definite boundary between secondary 

 and tertiary tracts, and that the first dawn or eocene period 

 of the present living organic creation, must be sought for 

 deeper than the chalk formation ; a view that appears to be 

 confirmed by the occurrence of a living Trochus below the 

 chalk, of the Paludina vivipara and Cyclas cornea in the 

 Weald Clay, and of the Terebrahda caput serpentis in the 

 Upper Oolite. But as this and other interesting conclusions 

 and views entertained by the author will be shortly laid open 

 to the reader, with a full detail of the progressive researches 

 made, I shall not now enter further upon the important mat- 

 ter contained in the volume. 



