KENDALL : PLEISTOCENE MOLLUSCA IN NORTH HUNTI NGDONSHIKE. 8/ 



§ 2. — The species still found living in the British Isles and contained 

 in the above lists which seem to call for some special 

 remark are the following : — 



1. Hygromia hispida L. 



This shell which occurs in great numbers in the deposit at 

 Woodston is the large, widely umbilicate form of British Pleistocene 

 deposits, the shells measuring 6'48 mm. in height and io"59 mm. in 

 width. Some recent Derbyshire specimens of this form — var. con- 

 cimia Jeff. — have a height of 5 '23 mm. and a width of S'Sy mm., and 

 the difference in the robust and compact growth of the fossil shells is 

 a most noticeable feature. We have here undoubtedly the ancestral 

 type of H. hispida. This extreme size in this species is especially 

 remarkable, for Scandinavian shells, which we have had the oppor- 

 tunity of measuring, only give measurements of 4*75 mm. in altitude 

 and 7 "46 mm. in width, and shells from the English Lake District are 

 very seldom any larger than this. 



2. Ena montana Drap. 



The one perfect specimen which I have so far found at Wood- 

 ston is a good typical shell measuring 13 "5 mm. in length. It is an 

 interesting record which suggests that the range of this species may 

 at one time have been considerably more extensive than it is to-day. 

 E7ia montana appears to be of very rare occurrence in the British 

 fossil deposits. iNTr. A. S. Kennard informs me that hitherto it has 

 only been found in the deposits at Barnwell and Grantchester in 

 Cambridge, and at Clacton in Essex, of Pleistocene age and in these 

 places but sparingly. 



3. Cochlicopa lubrica MuUer. 



The shells of this species from the Woodston deposit are about 

 a third as large again as the present British type and measure 

 7 "63 mm. in length with a width of 3.24 mm. in the type, and of 

 27 mm. in the variety lubricoides. Both forms are extremely common 

 in the deposit. Mr. A. S. Kennard tells me that this species as well 

 as Hygroinia hispida are very frequently of a large size in the Pleisto- 

 cene deposits. Recent specimens from Vermland in Sweden do not 

 measure more than 5 mm., while British specimens on an average give 

 5 to 6 mm. in length. 



4. Valvata macrostoma Steenbuch. 



I have so far only found one specimen of this shell in the deposit, 

 but it is quite a typical one of a species which cannot possibly be 

 confused with Valvata piscinalis Miiller. Owing to its recent dis- 

 covery living, at Lewes, in East Sussex, a good deal of interest now 

 centres in this species. Its occurrence in the Pleistocene deposits at 

 Clacton and Barrington, and now at Woodston suggests that it is one 



