PRESTWICH FOSSILIFEROUS IRONSANDS, N. DOWNS. 333 



tinuous stratum of fossiliferous iron-sandstone reposing on a bed of 

 very large chalk-flints, externally stained with iron, and a few pieces 

 of iron-sandstone. The sandstone was from 4 to 6 inches in thick- 

 ness." Mr. Harris considers, that, owing to the rise of the surface 

 from the first to the second section, the sandstone of the latter, if 

 continued eastward, would come out at the surface where the first 

 trench was dug. The beds in the second section, which seem to me 

 to be more like beds in situ, would, I think, be cut off before reach- 

 ing the first section, if I am right in considering the beds there to be 

 drift-beds. 



In a chalk-hole in the field west of Warren Street, and now just 

 filled up, I found this small section remaining, of strata which are in 

 situ : — 



ft. in. 



Yellow sand 1 



Mixed red clay and yellow sand 3 



Seam of compact ironstone, with traces of fossils 2 



Layer of small flint-pebbles 6 



Brown sand and clay 1 



Mr. S. V. Wood's Remarks on the Fossils from Lenham. — 

 " Mr. Prestwich has submitted to my examination a series of fossils, 

 on account of their bearing a general aspect to those of the Crag. 

 They consist of casts of shells in sandstone, &c, displaying some- 

 times the sculpture of the exterior, though oftener the shape only 

 of the interior of the shell ; and the majority of the specimens belong 

 to the bivalve division of the Mollusca. 



" The cast of a shell is at all times a very unsatisfactory dependence 

 for specific identification ; and, unless the same species be exhibited in 

 a bivalve, for example, with the sculpture of the exterior well displayed, 

 while another specimen will equally show the characters of the in- 

 terior with hinge or dental apparatus, no safe reliance can be placed 

 for a perfect identity with any species ; neither is a univalve, if the 

 aperture (upon which the generic character is sometimes dependent) 

 be not also in a perfect condition. In the present case, I am afraid 

 the most that can be said is, that there is a stronger resemblance in 

 these fossils to the shells of the Crag than to those of any other 

 formation, and what may also perhaps assist in the assignment is the 

 apparent absence of any decided species exclusively belonging to the 

 Older Tertiaries. There are, however, amongst them two or three forms 

 somewhat resembling species belonging to the Paris Basin, though in 

 these instances there is by no means an identification with any Older 

 Tertiary shell known to me ; still, if it be asked whether a perfect 

 reliance can be placed upon any specimens as truly characteristic of 

 the Crag period, I fear an answer must be given in the negative, 

 although the general aspect of the fossils is certainly favourable to 

 the assumption that they belonged to the Upper rather than to the 

 Lower Tertiaries ; and, as the locality whence they were obtained is 

 very remote, it is possible the two or three strangers may have existed 

 at the same time with our long- and well-known Crag species ; and, if 

 they cannot be identified with any of the Older Tertiaries, which I 



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