DISTRIBUTION OF GENERA AND SPECIES. 173 



and temperate portions of the American continent and 

 islands, their place being supplied by the genera Tehen- 

 noplwms and Vaginulus, the first in North and the 

 second in South America, the Antilles and that part of 

 Florida adjacent to Cuba. The only exception to this re- 

 mark is, a single and somewhat doubtful species of Limax, 

 common in the United States.' At the same time, the 

 climate is favorable to several species of foreign origin, 

 "which are rapidly spreading through the country. Vit- 

 rina only appears in America north of 44° north latitude. 

 Helix, a genus common to all the continents and large 

 islands, is most abundant in temperate latitudes of the 

 northern hemisphere, towards their southern limits, and 

 gradually diminishes in the number of its species, both 

 in approaching the equator, and in going into higher 

 latitudes. BiiUmus affects mostly the inter-tropical lat- 

 itudes, where it takes the place of Helix, while ki the 

 temperate latitudes of North America and of the east- 

 ern contment it is reduced to a very small number of 

 species*. In South America, however, which seems to 

 be the great numerical centre of the genus, the species 

 abomid as far as 25'^ south latitude. The European form 

 of Pupa, differmg however in specific characters, is 

 common to North America, and extends in a few species 



> The territory belonging to the United States, on the Pacific Ocean, south 

 of 49° north latitude, is also known to produce one or more species of 

 Limax, drawings of which were made by the artists of tlie United States 

 Ebcploring Expedition. We do not loiow whether the species have been 

 determined or not. 



