THE 



JOURNAL 



OF 



CONCHOLOGY. 



THE RELATION OF THE LAND AND FRESHWATER 



MOLLUSCA OF THE MADEIRAN ISLANDS, TO 



THOSE KNOWN ELSEWHERE. 



By the Rev. R. BOOG WATSON, B.A., F.R.S.E., F.L.S. 



Being his Valedictory Address as President of the Conchoi.ogical Society 

 FOR THE Year iSqi. 



The number of inland MoUusca, which excluding mere 

 synonyms have been attributed to these islands, is two hundred 

 and six. Two hundred and six species on an isolated sea-girt 

 speck of the earth's surface — a speck not four hundred square 

 miles in area ! The number is enormous. To what extent 

 are these two hundred and six species met with elsewhere? 

 That is the question I propose to answer. 



At the very outset, however, a reduction on the above 

 number must be made, for some of these species have obviously 

 no right of admission. Mr. Wollaston, the ablest of all judges, 

 in his ' Testacea Atlantica ' cuts down the list from two 

 hundred and six to one hundred an d seventy-eight ; a reduc- 

 tion of twenty-eight species which everyone will admit have no 

 right of residence whatever. Besides these twenty-eight, there are 



