8 Quarterly Journal of Conchology. 



herbage or stones in rather damp places "all the year round," but 

 early in the year, if the weather be mild, is the best time, before 

 vegetation gets too luxuriant and Phoebus too powerful, for our 

 little Cochlicopa, like many others of our native moUusks, is no 

 "feather-bed soldier" but bestirs himself ere yet the last snow has 

 departed before the soft breath of spring. 



Unlike its brother C. liibrica, C. tridens has a limited foreign 

 distiibution, being only reported from France and Germany, while 

 the former has a world-wide distribution. 



Handsworth, December \%th, 1873. 



THE MOLLUSCA OF EUROPE COMPARED WITH 

 THOSE OF EASTERN NORTH AMERICA. 



By J. GWYN JEFFREYS, F.R.S. 



[Reprinted, by the kind permission of the Author, from the Annals 

 AND Magazine of Natural History for October, 1872.] 



After mentioning that he 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 Mollusca of Europe with those of Massachu- 

 setts. 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. no 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 Verrill and Mr. Whiteaves on 

 the coast of New England 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 no), 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 

 tabulated 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 current southwards 

 toCapeCod, and the remainder from the Mediterranean and western 

 coasts ofthe 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 

 hospitality and attention which he received from naturalists during 

 his visit to North America last year. 



