Strata of the Islands of Seelaftd and Mden. 251 



which seems highly confirmatory of this view. We meet very commonly 

 in the chalk with the solid support of the Hipponyx, the body of the shell being 

 the same in form and structure as a Pileopsis, and this part having entirely 

 disappeared. We also find the lower valves of Crania in white chalk, these 

 valves being of the ordinary texture of bivalves, whereas the upper valves of 

 the same, which are less solid, are rarely if ever met with. According to this 

 analogy, the white chalk, even if it originally contained univalves as abundantly 

 as the Faxoe limestone, might now be destitute of them, and might present us 

 solely with bivalve shells*. 



Among other remains at Faxoe, the claws and entire shells of a small crab, 

 Brachyurus rugosus, Schlotheim, are not uncommon. Such Crustacea abound 

 on modern coral reefs, to which the mass of zoophytic limestone at Faxoe 

 bears so close a resemblance. 



The next point which I shall consider, is the age of the Faxoe beds, rela- 

 tively to the white chalk with flints. Although we have the evidence of direct 

 superposition at Stevensklint, that some beds of the Faxoe formation were 

 posterior to certain beds of white chalk, yet this circumstance appears to me 

 by no means conclusive of the general posteriority of the Faxoe corals and 

 other shells to all the white chalk of Europe, or even of Denmark. I may 

 observe that, although at Faxoe itself the coral limestone containing univalves 

 is the uppermost mass, or covered only with tertiary drift and boulders, yet 

 at Stevensklint, a rock (6. fig. 6.) containing similar fossils and resting on 

 white chalk, is by no means the newest of the cretaceous series, but is again 

 covered by a rock of considerable thickness, which I have called the upper 

 Stevensklint limestone {a. fig. 6.), and the fossils of this last correspond much 



Fig. 6. Faxoe. 



a Upper Stevensklint limestone. Interval of nine Depth of b unknown. 



6 Faxoe limestone. miles unknown, 



c White chalk. 



more closely to the white chalk, and are not distinguished by the most charac- 

 teristic remains of Faxoe. This fact seems clearly to show, that the distinct- 



* Since writing the above, Mr. Lonsdale has shown me many specimens of the upper valves 

 of crania, which he has found in an excellent state of preservation in the soft white upper chalk 

 of Gravesend and Portsdown in this country. He suggests that the supposed comparative abun- 

 dance of the lower valves may arise from their being attached to large fossil bodies. 



2 It 2 



