1.74 JOURNAL OF CONCHOLOGY. 



THE PRESENT STATE OF KNOWLEDGE OF THE 



DISTRIBUTION OF 



LAND AND FRESHWATER MOLLUSCA IN BRITAIN. 



It will facilitate the preparation of the proposed new 

 Monograph, and much assist conchologists and others who wish 

 to co-operate in its production if a table be given — which is now 

 done — showing the extent to which the projectors have had the 

 opportunity so far (to Dec. 31st, 1883) of examining specimens 

 from the various counties and vice-counties of the British Isles. 

 The numbers given in the columns of the table show how many- 

 species have been seen of each of the groups of inland moUusca, 

 and as the slugs will be the first group treated of in the 

 Monograph, their numbers are given independently of those of 

 the other land snails. 



Advantage is also taken of this opportunity to explain once 

 for all in what way the counties or vice-counties of the concho- 

 logical record or distribution-scheme differ from the political 

 counties. These differences consist essentially in the sub-division 

 of the larger areas, together with a certain amount of rectification 

 of boundaries by throwing the detached and isolated portions of 

 counties into the counties by which they are enclosed or 

 surrounded. 



A careful examination of the above table will show 

 conchologists (i) how very little has yet been examined with a 

 view of recording detailed distribution, and therefore (2) how 

 very easily each can help by submitting specimens from the 

 district he resides in or has opportunities of visiting. In addition 

 to these points, which every one will see for himself at a glance, 

 it will be well to urge upon attention the importance of sending 

 Slugs First, for as the Monograph is to be commenced with 

 this group, Testacella leading the van, it will be well to complete 

 as far as possible the geographical range of each species of this 

 group. And more especially is it desirable to pay pointed atten- 

 tion to the importance of sending living specimens to Leeds for 



J.C, iv., April, 1S84 



