Mr. J. G. Jeffreys on some British Shells, 309 



area just cleared of the flat table of flint. It was perfectly flat, 

 as was the upper surface also of the flint removed. No shell of 

 any large size was found on either surface. I observed however 

 in several places on the upper surface lines of much the same cha- 

 racter — though occurring for the most part only singly or few — 

 as the lines on the specimen figure 1, and which lines I cannot 

 doubt owe their existence to a slight motion of the water above 

 while the mass was in the act of solidification. 



In conclusion I would remark, that, while it has been abso- 

 lutely necessary for me, in order that some approach might be 

 made to the discovery of truth on this very interesting and oft- 

 mooted question of the formation of the flints of the upper 

 chalk, to show how much my language and views have been mis- 

 represented, and how contrary the facts are to the representa-^ 

 tions, I would not for a moment be thought to imply any inten- 

 tional misrepresentation in either respect on the part of Mr. 

 Bowerbank» It is one of the greatest evils of all " anticipation '' 

 that it tends to dim the sight and to warp the impression derived 

 from what seems the clearest fact or statement, and that any 

 fancied analogy (I use the word as more familiar than similitude) 

 is seized and dwelt on to the exclusion of numberless points of 

 dissimilitude. I trust that the observations of Mr. Bowerbank 

 may serve to advance the discovery of truth in this matter, if they 

 be the occasion of my rendering more clear the facts and reasons 

 which appear to me to demonstrate the existence of numberless 

 dissimilitudes between the facts of nature and the generalization 

 hazarded by him, and of enabling me to render also clearer the 

 suggestions which I have ventured to throw out, and which I 

 would fain hope . tend to elucidate in some degree the natural 

 history of the formation of the flints of the upper chalk. 



XXXIII. — Descriptions and Notices of British Shells. 

 By J. GwYN Jeffreys, F.R. & L.S. 



It was my first intention to have reserved for the work on Bri- 

 tish Mollusca, in which my friend Mr. Forbes requested my as- 

 sistance, the publication of any discoveiy on this subject which 

 may from time to time have occurred to me ; but as in his opi- 

 nion the anticipation by this mode of publication of any such 

 discoveries would increase, instead of diminishing, the interest of 

 the proposed work, I will give a short account of some import- 

 ant additions to the Catalogue of British Shells, for which I am 

 principally indebted to my indefatigable friend and collaborateur, 

 George Barlee, Esq., during his excursion to the western coast of 

 Scotland last year. 



