104 SUPPLEMENT TO THE CRAG MOLLUSCA. 
In the list in the Cor. Crag paper of Mr. Prestwich (‘ Quart. Journ. Geol. Soc.,’ vol. 
xxvii, p. 140) Mr. Jeffreys gives this species as identical with P. Islandicus, a Clyde 
fossil (Crag Moll.,’ vol. ii, p, 40, Tab. V, fig. 1); but from that I dissent, as the 
difference between them is not inconsiderable, both in the sculpture and the form of the 
shell, as also in that of the ears. 
Pecten princeps is not included by M. Nyst in his ‘ Descript. foss. de Belgique,’ 
1843; but in his later ‘ Listes des Fossiles des divers Htages’ the species is given from 
both the Sables gris and from the Sables jaunatres. 
If the living Zslandicus be, as is not improbable, the modified descendant, through the 
variety pseudo-princeps, of the older Pliocene form princeps of the Coralline and Belgian 
Crags, this again must have descended from some yet older form, and in this way the 
identification of species must go on indefinitely, unless such a line as seems necessary to 
me in this case be drawn. 
Puotmn Gurarpu, Wyst. Crag Moll., vol. u, p. 24, Tab. V, fig. 5. 
I know this shell only from the Cor. Crag. Mr. Jeffreys, in * Brit. Conch.,’ vol. u, p. 
68, speaking of Pecten Teste, says that it resembles P. Gerardi, but in his list of Crag 
shells in the ‘ Quart. Journ.,’ vol. xxvii, p. 140, P. Gerardi is referred to P. Gren- 
landicus, Chemn. My own opinion is that the Crag shell is distinct from either of those 
existing species. As before stated (‘Crag Moll.,’ vol. 1, p. 25,) it more resembles an 
American fossil, but I believe it to be distinct from all, although the concluding remark 
which I have made in the case of P. princeps applies, mutatis mutandis, to the case of 
P. Gerardi and P. Grenlandicus. 
Prcren varius, Linn. Crag Moll., vol. u, p. 41; Supplement, Tab. VIII, fig. 7. 
Localities. Cor. Crag, Sutton? Middle Glacial, Hopton. Post Glacial, Nar Brick- 
earth (Rose). 
The figure represents a small specimen found in the Cor. Crag, which I have provi- 
sionally referred as above, but it is a doubtful identification. Fragments of varius are 
not uncommon in the Middle Glacial sands of Hopton, but I do not know it from the 
Red or Fluvio-marine Crag, the Chillesford bed, or the Lower Glacial sands. 
PrctEn NivEus ? Macgillivray. Supplement, Tab. VIII, fig. 8. 
PrctEen Niveus, Macgill. Edin. Phil. Journ., vol. xiii (1825), p. 166, pl. iu, fig. 1. 
Locality. Cor. Crag, Sutton. 
