250 



J. P. Johnson — Cretaceous Rocks of Glynde. 



spinosa, but a little is probably Senonian, for the hard sub-crystalline 

 band known as the Chalk Rock, which in this country strati- 

 graphically separates the two periods, is certainly present, though 

 I have not been able to determine its exact position, as the section 

 has always been obscured during my visits by the talus resulting 

 from blasting operations. I have a series of thirty-nine associated 

 teeth of Ptychodus mammilaris from here in Chalk Eock matrix. 



Skirting the Chalk escarpment westwards, one at length arrives at 

 the classical Lewes quarries. They do not need to be dealt with 



