286 



PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 19, 



Three shells of the above list — Astarte Basterotii, Turritella in- 

 crassata, and Purpura tetragona — are so rare at Calloo, and so much 

 worn when they occur, that they are believed by M. de Wael to 

 have been derived from an older bed of the Middle or Grey Crag. 

 A single rolled valve of Astarte corbuloides is supposed, in like 

 manner, to have been washed out of an older bed. But the admis- 

 sion or omission of these fossils will not be found to affect the fol- 

 lowing conclusions, which may be drawn from the whole list : — 



1st. The result which is most striking, is that out of QQ shells no 

 less than 64 are common to the Suffolk Crag ; occurring either in 

 the red or coralline crags. There can, therefore, be no doubt of the 

 contemporaneity of the Upper Crag of Antwerp with the English or 

 Suffolk Crag. 



2ndly. Fifty-nine species out of 66 are common to the red, and 

 45 to the coralline crag, so that the resemblance to the red or upper 

 crag is greatest. 



3rdly. Thirty-seven out of ^(i, or more than half the shells 

 (55 per cent.), have been identified with living species ; and the ana- 

 logy of these with the fauna of the Northern Seas is very great, as in 

 the case of the Crag of Suffolk. 



The upper or yellow sand is usually unconsolidated, and for the 

 most part without shells ; often micaceous, and occasionally with a 

 slight mixture of argillaceous or calcareous matter. At Steuvenberg, 

 a locality before alluded to, which I visited, in the eastern suburbs of 

 Antwerp, some beds were formerly worked which were so calcareous 

 as to be used for roads, and even burnt for lime ; the carbonate of 

 lime appearing to be derived from the decomposition of shells. From 

 this spot M. de Wael has in the course of many years obtained the 

 following shells, which, like those of Calloo, have been compared with 

 British Crag species by Mr. Wood. 



Table III.* 



Fossil Shells from the Upper or Yellow Crag at Steuvenberg, in the 

 Eastern suburbs of Antwerp^ collected by M. Norbert de Wael. 



Cor. 



Red. 



Re- 



cent. 



1. Solen ensis, Linn 



2. Solecurtus candidus, Ren. ... 



3. Glycimeris angusta, Nyst ... 



4. Corbula gibba, Oliv 



5. Corbulomya complanata, iSoii;. 



6. Mactra arcuata, Sow 



7. striata, AT^/s^ 



M. dubia. Sow. 



8. Erycina ambigua, Nyst 



Kellia ambigua^ S. Wood. 



very rare, 

 rare. 



very common 

 very rare. 



rare. 



* The synonyms given in Table II. are not repeated here. 



