ECHmODEEMA — SEA-URCHINS. 



73 



and Hungary. In these, as in the later Echinoidea, the Gallery 

 interambulacrals were restricted to two columns, but the VIII. 

 test remained flexible. 



The British Mesozoic Echinoids include many speci- 

 mens described by T. Wright in his Monograph published 

 by the Palaeontographical Society. With the Jurassic series 

 we find the beginning of more familiar types. Cidaris Table-ease 

 Ediuardsi from the Lias has the jaws preserved, and the 

 radicles of various sizes still on the tubercles to which 

 they were attached by muscles when the animal was alive. 

 Here is also Acrosalenia, with specimens of the J. ijustulata 



Fig. 34. — Types of i Fossil Echinoidea. 1-5, Eegular ; 6-8, Irregular. 

 1,2, Carboniferous; 3-5, Jurassic; 6-8, Cretaceous. 1, Palaeechinus 

 sphserimis, side-view. 2, Archxocidaris, interambulacral plate and its 

 radiole. 5, Cidaris glandifera, primary radiole. 4, Hemicidaris inter- 

 media, side-view. 5, Salenia petalifera. 6, Dysaster ringens. 7,Enal- 

 laster Greenovi. 8, Catopygus columharius. 5-8 are seen from above, 

 with the anus towards the spectator. The figures are all somewhat 

 less than natural size, (By permission of Messrs. A. & C. Black.) 



that was found in crowds near Cirencester. The Jurassic 



fossils continue with the more modified Hemicidaris and Table-ease 



Pseudodiadema. Then come early forms of Diademina, such 



as Hemipedina and BiademojJsis, those from the Lias being 



but slightly removed from some of the Triassic species. 



They give rise, however, to more elaborate forms in the 



Oolitic rocks, e.g. the large HemijMdina (Fhymopedina) mar- 



chamensis, with its numerous tubercles. An interesting allied 



type is Pelanechinus, in which the plates were widened and 



flexibly united In this species have been found the little 



pincer-like appendages called pedicellariae, well known in 



living urchins, but rarely preserved on the fossils. 



