Correspondence — Hugh J. L. Beadnell. 287 



The numbers of Sir Joseph Prestwich's specimens are not stated, 

 •but the above table is probably the order of frequency of occurrence. 



Mr. E. R. Sykes, F.L.S. (President Conchological Society), has 

 found L. triincatiila in a deposit on the east side of the Isle of 

 Portland. He considers this latter deposit as compai'atively recent, 

 and derived from a marshy tract which still exists south of 

 Southwell. If this be so the deposits are not synchronous, 

 inasmuch as the geological conditions of the deposit at the Bill 

 are well defined as of late Pleistocene age, not only from the 

 stratigraphical evidence, but from the abundant occurrence of so 

 characteristic a Pleistocene form as S. oblonga. Mr. Sykes (Proc. 

 Dorset Field Club, vol. xvi, p. 171) records L. truncatiUa from the 

 ' Bill ' deposit. On referring to Prestwich's paper on the raised 

 beaches (Q.J.G.S., vol. xlviii, 1892, p. 278) Z. truncaiida is 

 determined from the occurrence of opercida onhj. Probably Bythinia 

 tentaculata is meant, as it occurs also at Chesilton at the north-west 

 of Portland, and is an operculate mollusc, whereas Limncea is 

 non-operculate (Reeve, " British Land and Fresh-water Mollusca," 

 1863, p, 154). This inadvertence may be a lapsus calami, either on 

 the part of our author or of Dr. Gwyn Jeffreys, who generally 

 determined doubtful or critical species for him. 



Limncea triincatula is therefore still a new record from this 

 interesting Pleistocene deposit. R. Ashington Bullen. 



AxELAND, Surrey. 



THE CENOJIANIAN OF BAHARIA OASIS, EGYPT. 



Sir, — I have to thank Dr. Max Blanckenhorn for his letter in 

 the Geol. Mag., April, 1900, p. 192, disclaiming to have himself 

 " discovered the existence of rocks of Cenomanian age in Baharia 

 Oasis." As Dr. Blanckenhorn maintains that he cannot be held 

 responsible for the abstract report which appeared in the Zeitschrift 

 fiir prahtische Geologic, 1 should liice to point out that the copy of 

 this abstract report was sent to the Survey by Di\ Blanckenhorn 

 himself, and although it contained numerous corrections in ink of 

 the type matter, the paragraph to which exception was taken, and 

 which I quoted in my letter of December 7, 1899, was not in 

 any way corrected or explained ; I could therefore only come to 

 one conclusion. 



As 1 have already stated my opinion as to the age of the series of 

 beds under discussion, both in my letter of December 7, 1899 

 (Geol. Mag., January, 1900), and in a paper read before the Cairo 

 Scientific Society in October, 1899, it is not necessary to discuss 

 Dr. Blanckenhorn's assertion that I did not " know the meaning " 

 of the fossils collected, especially as this has nothing to do with the 

 question in dispute. Moreover, as the examination of these fossils 

 has not yet been completed by the pala3ontologists of the British 

 Museum, the exact horizon or horizons to which they should be 

 referred cannot possibly be indicated with certainty. 



Cairo, April 14, 1900. HuGll J. L. Beadnell. 



