PKESTWICH CRAG-BEDS OF SUFFOLK ANB NOBFOLK. 



351 



jaunes of Antwerp and not in the Sables gris, with snch species as 

 survived to the glacial period in England, as species proper to the 

 Eed Crag. I doubt whether the circumstance of a shell being found 

 double in the Eed Crag is sufficient to identify it with that deposit, 

 as, from the compactness of portions of the Coralline Crag, I see no 

 reason why many should not have been transferred from one to the 

 other without break. 



Species probably derived from 



Terebratula grandis. 



Astarte Burtini, 



Basterotii. 



mutabilis. 



Cardita senilis. 



Cardium decorticatum. 



Chama gryphoides. 



Cyprina rustica. 



Diplodonta dilatata. 

 ? rotundata. 



Donax politus. 



Erycinella ovalis. 



Gastrochajna dubia. 



Hinnites Cortesyi. 



Leuconopsis Lajonkaireana. 



Limopsis aurita. 



Ostvea princeps. 

 ? Panopjea Faujasii. 



plicata. 



Pecten dubius. 



Pholadidea papyracea. 



Venus ovata. 



Cfecum mammillatum. 



the Coralline Crag. 



Cancellaria mitrajformis. 

 Chemnitzia costaria. 

 Conopleura Maravigna;. 

 Dentalium costatum. 

 Erato Maugerice. 

 Nassa labiosa. 



prismatica. 



? Natica varians. 

 Odostomia plicata. 

 Pleurotoma carina ta. 



semicolon. 



Pyrula acclinis. 

 Eissoa costulata. 

 Scalaria foliacea. 



fimbriosa. 



varicosa, 



Terebra inversa. 



canalis. 



Troehus Kicksii. 



villicus. 



Trophon alveolatum. 



consociale. 



Vermetus intortus. 



I feel that much uncertainty must still attach to such a list ; and 

 I may remark that Mr. Jeffreys takes the lesser number of 13 species 

 as derived. 



Allowing for this element, the result is that the species found in 

 the Eed Crag are as under : — 



Number according to Mr. Wood's list 239 



New species added by Mr. Jeflfreys and Mr. Bell 79 



Species regarded by Mr. Jeffreys as varieties 45 



Species for the first time identified as recent by Mr. Jeffreys 46 

 Extraneous species 46 ? 



Excluding the varieties and extraneous species, this leaves as 

 proper to the Red Crag 234 species, composed as under : — 



Total Living Extinct Proportion of 



species. species. species. extinct species. 



234 216 18 7-7 per cent. 



or, including the extraneous species : — 



273 240 33 13-7 per cent. 



"With regard to geographical distribution, Mr. Jeffreys shows that 



