350 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Mar. 7, 



determine to what extent the fossils of the coralUne crag* may have 

 been removed and re-imbedded in the red crag, especially as the 

 lithological structure and composition of these two deposits presented 

 every facility for such a transfer and assimilation. But in these clays 

 we have the organic remains preserved on the spot where they lived, 

 and in a condition to show that they did live there, and therefore 

 present true and good records. The number of specimens which we 

 collected was small, but I am glad to find that Mr. Searles Wood has 

 since ^asited the locality and obtained from it a more extensive col- 

 lection than we had time to make. He has had the kindness to fur- 

 nish me with the follomng list of the specimens he procured : — 

 MoLLUscA Gasteropoda. Cardium edule, Linn. 



Buccirmm imdatum, Linn. J^ucina borealis, Linn. 



Natica catena, Dacosta. , , Cypnna islandica, Linn. 



TuiTitella communis, Risso. ^^- ^eHma crassa, Pmn. 



Littorina littorea, Linn. " ^^*^' ^^^/- ^ 



obliqua, /. bow. 



MoLLUscA AcEPHALA. "- pr^etenuis Woodivard. 



Mactra ovalis, /. iiow. 



5. Mytilus edulis, Linn. (]\I. elliptica. Brown.) 



Modiola discrepansf? Mont. 20. Abra alba, Wood. 



Nucula tenuis, Mont. (Mactra Boysii, Mont.) 



Cobboldiag, Sow. Panopaa norvegica, Spengl. 



Leda artica, G. Soiv. Mya truncata, Linn. 

 (Nucula lanceolata, Min. Con.) 



1^' myalis. Balanus communis. 



(Nucula myalis, Couthouy.) Echinus ? 



Cardium groenlandicum, Chemn. 



Mr. Wood obsen es, in speaking of this deposit, that it '^ has an 

 arctic character, and that he has very little doubt of its belonging to 

 a period posterior to that of the red crag, and equivalent probably 

 to the mammaliferous." He also calls attention to the large quan- 

 tity of Foraminifera|: which the sand contains. This opinion of an 

 authority such as Mr. Wood we feel to be important, and our own 

 observations with regard to superposition would, provided we had 

 been able to give it greater extension northward, render this view of 

 the age of these beds a probable one ; for we have shown that these 

 fossiliferous clays and sands immediately underlie the till or great 

 conglomerate clay-drift, and overlie indiscriminately both the coral- 

 line and red crag, than both of which it must consequently be newer. 

 But the palseontological evidence is, I think, far from being suffi- 

 ciently decisive, although good and clear as far as it goes. We yet 

 want to trace by superposition the connecting links between the dif- 

 ferent beds of this district and those of the neighbourhood of Norwich. 



^&' 



* See remarks on this subject by Mr. Charlesworth in his several papers on the 

 Crag in the ' Magazine of Natural History' for 1835, and in the ' Lond. and Edinb. 

 PhiL Mag.' for 1836. 



t Specimen imperfect. 



X ^Ir. Wm. Cunnington of Devizes, in a letter to me on this subject, observes, 

 " I have not been able to examine the sand from Chfllesford with the attention 

 which I could have vsished. Eight or ten species of these minute fossils, chiefly 

 of the genera Rosalina and Rotalina, have been recognized. The genera are less 

 numerous and less varied in the sands of Chillesford than in the sands of the 

 coralline crag, but the individuals of each species are veiy abundant." 



