BRITISH FOSSILS. 



DECADE THE FOURTH. 



All the plates and descriptions in tliis Decade are devoted to fossil 

 Echinodermata of the order Echinoidea. 



The genera selected for illustration are Temnechinus, A crosalenia, 

 Hyhoclypus, Hemipneitstes, Ananchytes with its section Holaster^ 

 and Cardiaster. The geological age of the first is Upper Tertiary, 

 of the second and third Oolitic, of the remainder Cretaceous. 

 Several of the species are represented for the first time. 



Temnechinus is a genus remarkable for its species being at 

 present known only as fossils of the Coralline and Ked Crags ; it is 

 now characterized for the first time. 



The examples of A crosalenia selected are both remarkable for 

 their beauty and their very perfect condition. They are also of 

 much interest, one on account of the rectification of its true generic 

 position, which I have been enabled to make through the aid afforded 

 by very perfect specimens : the other, because of the complete 

 preservation exhibited by the specimens described of parts too often 

 lost in fossil Echinoderms. I have appended to the descriptions of 

 these Acrosaleniw brief characters of some new species of this 

 interesting oolitic genus. 



Hyhoclypus is illustrated by the finest and largest species of the 

 genus, one discovered during the researches of the Geological 

 Surveyors. 



[IV.] 



b 



