290 



OUR COMMON BRITISH FOSSILS. 



Red Crag into two series the lower, characterized by 

 oblique lamination ; and the upper by persistent hori- 

 zontal bedding. The lower part is much richer in 

 shells than the upper. The most abundant in the 

 Red Crag are the Common cockle, Cardium angusta- 

 tum, Pectunculus gly timer is > Tellina crassa, T. obliqua, 

 Mytilus edulis, Pecten opercnlaris> Cyprina islandica, 

 Lucina borealis, Cardita senilis, 

 Purpura tetragona> P. lapillus, Tro- 

 phon (or Fusus) antiquus, T. con- 

 trarius, Nassa reticosa^ N.granulata, 

 Astarte Omallii, Cyprcza Europ<za> 

 etc. In many places, as at Tatting- 

 stone, Bentley (in the pits near the 

 station), Foxhall, Bucklesham, and 

 elsewhere, the strata teem with 

 Pectunctulus, Trophon contrarius, 

 tetra- Cardita senilis, Nassa, etc. 



gona (Crag beds). The number of S p ecies Q f f ossil 



mollusca belonging to the Red Crag is two hundred 

 and thirty-four, of which two hundred and sixteen are 

 still in existence. In addition to this number, we 

 must include about forty extraneous species. About 

 one hundred and fifty of the above species are still 

 living in British seas, whilst of the remainder, thirty- 

 two are southern forms, and twenty-three northern 

 a total of nine more northern species than are found in 

 the Coralline Crag, thus far indicating a refrigeration 

 of the climate. 



