118 



Thos. Roberts — Cretaceous Echinoich. 



In the collection of fossils presented some time a^o to the Woocl- 

 wardian Museum by the late Montagu Smith, Esq., of Trinity- 

 College, Cambridge, is rather an* interesting specimen of Peltastes 

 Wrightii, from the Farringdon Beds of Farringdon. In most of its 

 characters it agrees with the normal examples belonging to this species, 

 but it differs from them in possessing twelve plates in the apical disc. 

 The centro-dorsal plate, five radials, the unpaired and the two left 

 and the right posterior basals are perfectly normal ; but the right 



1. Peltastes WrigJitii, from Greensand, Farringdon. m, madreporic plate; 



s, supplementary plate. 



2, 3, 4. Hchinoconus subrotundus, Shudy Camps, Cambridgeshire. 



anterior basal (madreporic) is smaller than any of the other basals, 

 and its genital pore is situated relatively nearer the inner border of the 

 jolate than is the case in any other specimen which I have examined. 

 Further, its inner border is somewhat concave, whereas in the 

 ordinary examples it is straight. Interposed between the madrepo- 

 rite plate and the centro-dorsal, and bounded laterally by the left 

 anterior and right posterior basals, is a distinct plate which is roughly 



