302 



REPORT 1872. 



Report on the Mollusca of Europe compared with those of Eastern 

 North America. By J. Gwyn Jeffreys, F.R.S. 



[A communication ordered by the General Committee to be printed in extenso.'\ 



After mentioning that lie had dredged last autumn on the coast of New 

 England in a steamer provided by the Government of the United States, and 

 that he had inspected all the principal collections of Mollusca made in Eastern 

 North America, the author compared the MoUusca of Europe with those of 

 Massachusetts. He estimated the former to contain about 1000 species (viz. 

 200 land and freshwater, and 800 marine), and the latter to contain about 

 400 species (viz. 110 land and freshwater, and 290 marine); and he took 

 Mr. Binney's edition of the late Professor Gould's ' Report on the Invertebrata 

 of Massachusetts,' published in 1870, as the standard of comparison. That 

 work gives 401 species, of which Mr. Jeffreys considered 41 to be varieties 

 and the young of other species, leaving 360 apparently distinct .species. 

 About 40 species may be added to this number in consequence of the recent 

 researches of Professor VerriU and Mr. Whiteaves on the coast of New Eng- 

 land and in the Gulf of St. Lawrence. Mr. Jeffreys identified 173 out of the 

 360 Massachusetts species as European, viz. land and freshwater 39 (out of 

 110), and marine 134 (out of 250), the proportion in the former case being 

 28 per cent., and in the latter nearly 54 per cent. ; and he produced a tabu- 

 lated list of the species in support of his statement. He proposed to account 

 for the distribution of the North-American Mollusca thus identified, by 

 showing that the land and freshwater species had probably migrated from 

 Europe to Canada through Northern Asia, and that most of the marine species 

 must have been transported from the Arctic seas by Davis's-Strait cui'rent 

 southwards to Cape Cod, and the remainder from the Mediterranean and 

 western coasts of the Atlantic by the Gulf -stream in a northerly direction. 

 He renewed his objection to the term " representative species." The author 

 concluded by expressing his gratitude for the kind hospitaUty and attention 

 which he received from naturalists during his visit to North America last year. 



Mollusca of Eastern North America, according to Binney's edition of Gould'' s 

 '■Tnvertehrata of MassacJmsetts,' 



