VIII. 



OF THE DISTRIBUTION OF GEXERA AND SPECIES IN THE 

 UNITED STATES, COMPARED WITH THAT OF EUROPE 

 AND SOUTH AMERICA. 



The distribution of the terrestrial mollusks in the 

 United States, as compared with the temperate parts of 

 Europe, presents some curious results. The following 

 table shows the number of species found under the sev- 

 eral genera : 



