288 



OUR COMMON BRITISH FOSSILS. 



portions of the Red Crag which exhibit the true 

 features, often very extreme, of false bedding." The 

 beds of phosphatic stones (commonly termed " copro- 

 lites ") for which the Red Crag is so much worked on 

 the left bank of the Orwell, are seldom found beneath 

 such sections of the beached-up Crag. 



Fig. 282. Mya arenaria (Crag formations and recent). 



Mr. Searles Wood, sen., pointed out that the Red 

 Crag at Walton-on-the-Naze was the oldest bed. The 

 reasons rest on the universal absence of certain shells 

 abundant in other parts of the Red Crag, among others, 

 of Fusus antiquns, Tellina obliqua, Tellina pratenuis, 



