﻿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 Possiles des divers Etages ' the species is given from 

 both the Sables gris and from the Sables jaunatres. 



If the living Islandicus 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. 



Pecten Gerardii, Nyst. Crag Moll., vol. ii, p. 24, Tab. V, fig. 5. 



I know this shell only from the Cor. Crag. Mr. Jeffreys, in ' Brit. Conch./ vol. ii, p. 

 68, speaking of Pecten Testes, says that it resembles P. Gerardii, but in his list of Crag 

 shells in the ' Quart. Journ.,' vol. xxvii, p. 140, P. Gerardii is referred to P. Grceu- 

 landicus, Chemn. My own opinion is that the Crag shell is distinct from either of those 

 existing species. As before stated (' Crag Moll.,' vol. ii, 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. Gerardii and P. Grcenlandicus. 



Pecten varius, Linn. Crag Moll., vol. ii, 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 

 Bed or Eluvio-marine Crag, the Chillesford bed, or the Lower Glacial sands. 



Pecten niveus ? MacgiUivray. Supplement, Tab. VIII, fig. 8. 



Pecten niveus, Macgill. Edin. Phil. Journ., vol. xiii (1825), p. 1GG, pi. iii, fig. 1. 

 Locality. Cor. Crag, Sutton. 



