38 JOURNAL OK CONCHOLOGY, VOL, ID, \0. 2, APRIL, I9OI. 



Possibly this may be due to the fact that paleontologists usually 

 devote themselves to one special formation alone, and therefore a 

 general support is not forthcoming. 



As another comparative test we may note that at the commence- 

 ment of the century only about forty or fifty new species were 

 described every year ; whereas to-day we have to record something 

 like two hundred new genera or sub-genera (recent and fossil) and 

 nearly one thousand living species. 



At the present day generic monographs abound, good faunistic 

 works are numerous ; societies such as ours are found in many coun- 

 tries, and periodicals devoted to our special study vie with one 

 another in giving to the world the latest discoveries. Conchology has 

 ceased to be the pastime of the rich, and has become the study of 

 those whose purses could not in bygone days reach the price of speci- 

 mens. Exchange of duplicates has, owing probably in a large measure 

 to cheaper rates of carriage, become systematized and largely deve- 

 loped ; although, of course, some form of it must have taken place in 

 bygone days, the earliest "exchange list" that I have seen is one 

 distributed by Menke to accompany his well known " Synopsis " of 

 1828. It was in manuscript, and entitled " Catalogus testarum mol- 

 luscorum quae supervacanae prostant apud Car. Theod. Menke, M.D." 

 It contained the names of 207 Gastropods and 58 Pelecypods ; all the 

 land and freshwater shells being European. 



Still, this very abundance of literature has to us its disadvantages ; 

 almost every shell which has been known for more than, say, ten years 

 has its synonymy ; authors with insufficient material and a zeal for 

 "species-making" have crowded and overburdened our lists with a 

 mass of names for indistinguishable forms and varieties. At the pre- 

 sent time no one probably would maintain that, for instance, the 

 European Xerophila, or the North American Unionidce, consist of 

 nearly as many species as there are admitted names, and one of the 

 most serious tasks which will lie before the students of the coming 

 century will be to reduce chaos in these and many other groups to 

 something resembling order. 



The rules of nomenclature, also, though obeyed in theory, are 

 broken in practice by many leading workers again and again. In our 

 own experience as students of British shells we find that in the same 

 lists some of Da Costa's names are used, others not ; one great diffi- 

 culty being that while these rules most carefully provide that binomial 

 nomenclature is to be used, they throw no light on the question as tO' 

 whether an author is to be recognized who is partly binomial and 

 partly non-binomial in the same volume or series of volumes. 



The relations between the Tertiary, Post-Tertiary, and recent faunas 

 of the British Islands form a problem upon which much light is 



