vi 



BRITISH FOSSILS. 



belonging to old genera, the Uraster Gaveyi is singularly interesting, 

 presenting, as it does, the spectacle of a Liassic echinoderm, which so 

 closely resembles the commonest star-fish now living in the British seas, 

 that it can only be distinguished from it by a minute and critical com- 

 parison ; and the Hemicidaris Purheckensis is remarkable as being the 

 first member of its tribe ever discovered in strata of the Purbeck series. 



The species described and figured have been selected from forma- 

 tions of different geological epochs. From Silurian rocks Lepidaster 

 Grayii has been taken ; from older secondary strata, the two forms of 

 Hemicidaris^ the Galerites {Holectypus) hemisphcerica, chosen on ac- 

 count of its being new to Britain, and also affording an excellent illus- 

 tration of the sub-genus to which it belongs, and the Dysaster ringens, 

 selected for the same reasons ; also the new star-fishes, species of 

 Uraster and Tropidaster^ already alluded to. Of cretaceous fossils 

 there are the critical Galerites casfaneus, and the characteristic Gale- 

 rites albogalerus and Micraster cor-anguinum. 



A third series of illustrations of the fossil Echinoderms is far ad- 

 vanced, and in preparation for publication. 



Edward Forbes. 



June, 1850. 



