322 



THE GEOLOGIST. 



Slowly the bright green tide is quitting the flat shore, and leaving 

 again exposed the dark blue clay, dotted with black phosphatic nodes 

 and glittering iridescent shells, washed clean and bright. Daily may 

 you pick up hundreds of these ancient inhabitants of the sea ; 

 gather the crop as clean as you will, there will be another harvest 

 for you when the next tide falls. Here are Inocerami, or " fibre- 

 shells," in abundance. Two species, the Inoceramus sulcatus and 



Lign. 24s.— Inoceramus sulcatus. 



Lign. 25. — Inoceramus concentricus . 



Inoceramus concentricus — the furrowed and concentric are particularly 

 characteristic of the gault. There is a third and rarer species, I. 

 Goquandi, which is also found in the dark-coloured upper green-sand 

 a short distance beyond, towards the old gun-brig " The Pelter," 

 The individuals of these species, so remarkably abundant in the 

 gault, rarely attain to the size of a few inches in leng-th, while other 



Ligu. 2G. — JS'iicula pectinafa. 



Lign. 21 .—Nacula ovata. 



species of " fibre-shells" of the subsequent era of the chalk attained 

 dimensions of more than a yard in diameter, with shells, however, 

 singularly thin for such large molluscs living in a sea conspicuous for 



