214 CHAPTER II 



B. Freshwater animals. 

 MoUusca 



Gyraulus parvus Say Lymnaea columella Say 



Heltsoma dtiryi Weth. L. cubensis Pfeiff. 



H. tenuis Phil. Physa ancillaria Say 



H. trivolve Say Ph. gyrina Say 



Lymnaea catascopium Say Ph. heterostropha Sayi 



The corresponding European element in North America is almost non-existent. 



The reasons for its poor effect 



Judging from the present character of trade and exchange of goods between 

 Europe and North America, one would perhaps feel inclined to expect that an 

 unintentional transport of animals and plants across the Atlantic would have been 

 more easily realized in an eastward direction. There is more material suitable for the 

 purpose, such as vegetable food, wool, timber, &c., shipped from North America to 

 Europe than in the opposite direction. 



The present conditions, however, are but little pertinent to the matter. It 

 seems that the main bulk of introduced species, especially of the Europeans 

 naturalized in North America, arrived prior to modern steam and motor traffic, the 

 first transatlantic line of this kind being opened in 1840 (Cunard Line: Liverpool- 

 New York), Earlier records from North America are available for at least the 

 following European species: — 



Sitotroga cerealella 01., the Angoumois Grain Moth, is reported to have been 

 observed in North America as early as 1743 (Essig, 193 1, p. 824). 



The Hessian Fly, Mayetiola {Phytophaga) destructor, was first described by Say 

 in 1816 and observed on Long Island, N.Y., as early as 1779, but is usually regarded 

 as a European introduction. 



Argyroploce pomonella L., the Codling Moth, was also introduced in the i8th 

 century. 



The Carabid Beetle Harpalus affinis Schrk. {aeneus F.) was described from North 

 America in 1805 by Beauvois under the name of viridiaeneus, a clear synonym. 



Similarly, the father of North American entomology, Thomas Say (i 787-1 834), 

 described some insects and other arthropods now regarded as of Old World 

 origin, for instance the Carabid beetle Bembidion tetracolum Say [ustulatum auctt., 

 nee L.), the Dung-beetle Aphodius fasciatus 01. (putridus Hbst.; as tenellus Say), 

 the Milliped Nopoiulus venustus Mein. (as pusillus Say; vide Palmen, 1952, p. 26), 



^ In part established in outdoor conditions. 



