TRILOBITES AND OTHER FOSSIL CRUSTACEA. 207 



cemetery. How abundant they are there may be 

 best stated by saying that Sheppey /^jj// lobsters may 

 be bought In the Strand geologist's shop for sixpence 

 each — a good deal cheaper than the price of the 

 recent lobsters In the other shops, a door or two away. 



Still, at Sheppey, and elsewhere, these fossil crus- 

 taceans have to be dug out of the clay, or else the 

 collector takes advantage of the weather and the 

 waves having washed them out of exposed cliffs. 



In Suffolk we are very advantageously placed In 

 this respect. The weather and the waves washed all 

 the harder Eocene fossil Crustacea out of the London 

 Clay, perhaps during the Eocene period, and they 

 were collected together in hollows and other protected 

 places. The area these fossils occupied subsequently 

 became a sea-floor, and the old derivative fossil 

 crustaceans were thus covered up by the dead shells 

 of a later period, and were even subjected to the 

 indignity of having their petrified corpses made use 

 of as settling-places for Red- Crag barnacles (retro- 

 grade representatives of the class of which they were 

 aristocrats) ! 



Anyhow, you can get any number of fossil crabs 

 and lobsters — Brachyura, Anomoura^ and Macrura — 

 in the heaps of phosphatic nodules collected together 

 and awaiting carting, in the neighbourhood of the 

 " coprolite " pits about Ipswich and Felixtowe. 

 The commonest of these fossil crustaceans are 

 Xajithopsis^ Thenops, Zaittholites, Hoploparia^ Archceo- 



