352 



ADDENDA, 



EUROPEAN GPECIES. * NORTH AMERICAN SPECIES. 



PossARUs Adansoriii. Ph. ( Rissoa Bryerea. J Mont, 



LiTHOGLYPHD.s fulvus. Mulilf. J Paludina vivipara. Linn. 



" Bcalaris. Zgl. t 



Mytilus eclulis. Linn. ' 



SUMMARY. 



European species. 840 



North American species . . .-^ 97O 



Deduct species common to Part I and Part II 37 



Total 1773 



REMARKS. 



Of the terrestrial species common to Europe and to North America, which arc 

 represented in this collection by individual;? from both continents, Helix arbusto- 

 rum, H. aspersa, H. hortensis, and H. virgata have been introduced into North 

 America, being found only near a few seaports, mostly at Cape Ann and at Port- 

 land. The same is probably true of H. cellaria (H. glaphyra. Say,) which is 

 found at Boston and Philadelphia, On the other hand, H. pulchella is so widely 

 distributed on both continents, that it is difficult to account for its introduction 

 from either to the other. The case of Physa hypnorum and Paludina vivipara is 

 similar, except that they are less widely distributed in this country. 



I am unable to detect the difference between Helix lucida of Europe, and a va- 

 riety of the North American H. arborea. which has the shell qf a dark brilligmt 

 translucent brown and the animal black, and which, unlike the typical variety, in- 

 habits wet places. The geographical distribution of this variety and its speci'fie 

 character need farther investigation. Nor is it easy to distinguish the European 

 Limnaea minuta from the American L. desidiosa. 



Errata on p. 24, after Cylindrella pygmaea, insert J. 



" " " first line of second column, for H. read P. 



" " " after Pupa contracta and P. rupicola insert Jl 



" " " for Bnli^-nus procerus J Ad., read BuHmus subula J Pf 



^4=-^ P^/^ 



