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. Ona 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 espéce est citée dans mon catalogue ; ce- 
pendant il se pourrait qu’elle ne fut qu’une variété un peu enflée 
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 paleontologist, who kindly sent us the specimen, 
“trés rare. J’en ai encore trouvé que trois morceaux de cette 
espéce.” 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 Loriére, we have before us specimens of 
P. Gervillii, Ag., from the Kellovien étage of Chauffour, 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 Chauffour, 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- 
ceeding 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). 
