310 ME. P. W. HAEMER ON THE LENHAM BEDS [Aug. 1 898, 



shall attempt to distingiiisli between those forms which I think may, 

 and those which may not be considered as representative of each 

 bed. It is difficult in some cases to know where to draw the 

 line, and possibly the experience of other collectors may not always 

 coincide with my own ; I hope, however, that reliance ma}'- be placed 

 on the general conclusions to be drawn from my lists. 



II. The Leistham Bebs. 



Our knowledge of the Lenham fossils is principally due to Mr. 

 Clement E-eid, who from the most unpromising material has suc- 

 ceeded in obtaining from that locality a collection of 61 species of 

 moUusca, not including 6 as to the identification of which he is in 

 doubt.^ This list, though doubtless containing but a small propor- 

 tion of the molluscan fauna of the period, may possibly be considered 

 as fairly representing it.^ The 67 species named belong to 50 

 genera, and they are more or less of a character similar to those found 

 in the Coralline Crag. With the exception of 15 (or 23 per cent.), 

 they all occur in that deposit. 



In the work just mentioned ^ Mr. Eeid groups the Lenham Beds 

 with the sands of Louvain and Diest, and with the fossiliferous strata 

 of Antwerp and Utrecht, and, taking them as a whole, he considers 

 that they are of the same age as, or even slightly newer than, the 

 Coralline Crag. I have given elsewhere my reasons for believing 

 that some of the strata met with in the Utrecht boring, regarded by 

 Dr. Lorie^ as Diestien, belong to the Scaldisien, that is, to a more 

 recent formation,^ and I do not think that auy of them are as old as 

 those of Lenham. The sands of Diest and Louvain, including the 

 zone a Terehratula grandis, are now believed by Belgian geologists, 

 and I think with reason, to be older than the Antwerp beds (zone a 

 Isocardia cor). It is the latter zone onl}^, and not the whole of the 

 deposits generally known as Diestien, which represents, I consider, 

 the Coralline Crag of Suffolk, 87 per cent, of the mollusca from 

 the Isocardia-hediS, occurring also in the latter. On both pal aeon to- 

 logical and stratigraphical grounds, I believe that the Lenham Beds, 

 although undoubtedly of Pliocene age, as held by Prestwich and 

 Wood, may be considerably older than the Coralline Crag. 



^ Mem. Geol. Surv. ' Pliocene Deposits of Britain,' 1890. 



^ [In the discussion which followed the reading of this paper, Mr. Eeid 

 suggested that if the smaller forms of the Lenham fauna were known, its 

 general character might appear to be different. He considers that ' the smaller 

 mollus(!fe. generally give a larger percentage of persistent forms.' I doubt this 

 A^ery much. An examination of the molluscan fauna of the Coralline Orag, 

 the other deposit in question, does not seem to me to lend any support to such 

 a view.— May, 1898.] 



3 Op. cit. p. 57. 



* ' Contrib. a la Geol. des Pays-Bas,' No. 1, Extr. des Archives du Musee 

 Teyler, Haarlem, ser. ii, vol. ii (1885). 



° Quart. Journ. Geol. Soc. vol. lii (1896) p. 762. It does not seem to me 

 that any of the Pliocene deposits described by Dr. Lorie are older than the 

 Coralline Crag. 



