492 H. A. Pilshry — Air-hreathing 3Iollusks of the Bermudas. 



ships of this genus are with Gastrodonta, a genus of the eastern 

 United States, which comprises species with an internal lamella, as in 

 P. circuinfirmatus, and others without it, as in the other Pcecilozon- 

 ites. The very peculiar genitalia leave no doubt as to the alliance 

 between Gastrodonta and Pcecilozonites. No closely allied forms are 

 known from the Antilles or from Europe. It appears therefore that 

 the oldest element in the Bermudian Pulmonate fauna is distinc- 

 tively North American, while all the rest of the endemic fauna is 

 Antillean. 



The single Veronicella of the fauna has, so far, not been found 

 elsewhere, but it may yet prove to be exotic. 



The second group of forms consists of species common to Ber- 

 muda and the Antilles, Omitting the AuriculidcB, Siphonariidoe., 

 Onchidiidce, and Truncatella, which from their littoral habits and 

 tolerance of salt water have exceptional facility in over-sea journey- 

 ing, we find some eight species of truly terrestrial forms which 

 apparently reached Bermuda by natural means of transportation, and 

 are not modified from the parent stocks. 



Thy sanophora vortex., Greater Antilles, Bahamas, Southern Florida. 



Polygyra '}nicrodonta, Bahamas. 



Zonitoides minusculus, Greater Antilles ; whole United States. 



Pupa [Pifidaria) servilis, Cuba, Bahamas. 

 " " rupicola, Cuba, Florida. 



" " jamaicensis, Jamaica. 



Pupoides marginatus, Greater Antilles ; U. S. 



Succinea harhadensis, Barbados, and under various names, some 

 other islands. 



The small or minute size of all these is noteworthy ; the Succinea 

 being the largest species which has been able to journey so far 

 over sea. 



The whole series of littoral air-breathers {Auriculacea and Trun- 

 catella) likewise belongs to the Antillean group, the species being in 

 all cases either identical with West Indian forms, or but very 

 slightly modified. 



A third element of the Bermudian fauna consists of those forms 

 which have probably been transported thither by human agency ; and 

 as the date of introduction of the several forms is a matter of some 

 interest to those who may hereafter stud}'- their variation in a new 

 environment, I give below the data for each species so far as prac- 

 ticable. 



