from the Lias and Oolites. 31 



that it is only a larger individual of P. aspera, as we find it in 

 the Inferior Oolite, and is identical with the fossil which we 

 have described as P. rotata. On a further examination of this 

 specimen, M. Agassiz, it would appear, had arrived at a similar 

 conclusion, for on the ticket which accompanies it is the follow- 

 ing remark in his handwriting : " Pedina granulosa, Ag. C'est 

 sous ce nom que cette espece est citee dans mon catalogue; ce- 

 pendant il se pourrait qu'elle ne fut qu'une variete un peu enflee 

 de mon P. aspera" This species was collected by Prof. Deslong- 

 champs from the Great Oolite of Ranville. We have likewise 

 before us a portion of Pedina collected from the Oxford clay of 

 the Boulonnais by M. Bouchard-Chantereaux, and marked by 

 that eminent palaeontologist, who kindly sent us the specimen, 

 " tres rare. J'en ai encore trouve que trois morceaux de cette 

 espece." It so nearly resembles the Ranville Urchin that we 

 have no doubt of their identity. By the extreme kindness of M. 

 Michelin and M. de Loriere, we have before us specimens of 

 P. Gervillii, Ag., from the Kellovien etage of. Chauffeur, depart- 

 ment of the Sarthe, which are identical with Pedina aspera or 

 rotata, collected by us from the upper beds of the Inferior Oolite 

 of Gloucestershire. In fact the French and English specimens 

 are so entirely alike, that we should mistake the one for the other 

 had we not previously marked them. It would appear from these 

 remarks, that whether we retain the specific name rotata or 

 aspera for this widely distributed Urchin, we must at least cancel 

 the other names which have been given to various forms of the 

 same, as we have now before us well-preserved specimens from the 

 Inferior Oolite, Gloucestershire, the Great Oolite, Ranville, Cal- 

 vados, the Oxford clay near Boulogne, Pas de Calais, the Kello- 

 vien of Chauffeur, Sarthe. 



[Since these sheets were sent to press, the Rev. A. W. Gries- 

 bach has communicated a Pedina, collected by him in the Corn- 

 brash at Rushden, Northamptonshire; as this fossil is in a 

 good state of preservation, we have been able to make a careful 

 comparison of it with a fine P. aspera now before us, and there 

 can be no doubt of their identity. The discovery of this Urchin 

 in the Cornbrash is another link in the chain of evidence showing 

 the wide stratigraphical range of this form in the Oolitic seas.] 



P. Bakeri differs so entirely from the forms named in the pre- 

 ceding remarks, that it is impossible to mistake it for either of 

 them ; its diagnostic characters consist of the size and small 

 number of the primary tubercles, the absence of secondary 

 tubercles, the scanty granulation on the interambulacral areas, 

 the narrowness of the ambulacra, and the single row of tubercles 

 thereon. We have only met with the small but tolerably per- 

 fect specimen of this species figured (PL I. fig. 4, a-c). 



