BRITISH NON-MARINE MOLLUSC A. 



51 



the stone walls in various localities up to 950 ft. or thereabouts. 

 In the mountain regions of the North of England and in Scot- 

 land much more might be accomplished in tabulating the alti- 

 tudes to which the various species ascend than in the Cottes- 

 wolds. For example, in the Grampians, on Ben Lawers in 

 Perthshire, Dr. Grant Guthrie has recorded Clausilia bidentata 

 from an elevation of 2400 ft., while more recently the sub-Arctic 

 Limax tenellus has been discovered in abundance in the elevated 

 pine woods of the great Forest of Bothiemurchus, in the same 

 region, by the Bev. Bobert Godfrey. It is thus very possible 

 that there are several Arctic and Alpine species, or at least 

 varieties, of Mollusca yet to be added to the British fauna from a 

 study of their vertical distribution in this country. 



The following table must only be considered of a temporary 

 character. The chief difficulty in the way of tabulating the 

 vertical distribution of the Cotteswold Mollusca is to be found in 

 procuring data for their inferior rather than their superior 

 range, owing to nearly all the lower levels being monopolized by 

 agriculture ; while, on the other hand, some species undoubtedly 

 will require to have their area of occurrence extended upwards. 

 It will be found, however, approximately accurate, and will serve 

 its purpose sufficiently, perhaps, as a suggestion as to what 

 could and should be done in other districts, if conchologists 

 would only deviate from the frequent course of forming huge 

 collections without reference to the important scientific service 

 which would undoubtedly accrue from a study of the environ- 

 ment whence their specimens were obtained. This is a subject 

 which the Conchological Society might undertake officially in 

 the same way as has been done in recording the horizontal 

 distribution. 



If in penning these few lines I shall have been the means of 

 inducing others to take up a branch of study which has afforded 

 so much pleasure to myself, I shall feel sufficiently rewarded for 

 the trouble I have taken. 



