LAND AND FRESH-WATER SHELLS 



NORTH AMERICA. 



III. 



Family AMPULLARIIDAE. 



Lingual membrane with seven series of teeth (3, 1, 8), 

 central teeth acute, lateral subulate. Eostrum divided into 

 two long tentacular lobes in front; tentacles long and fili- 



Fig. 1. 



Fig. 2. 



Lingual dentition of Pomus depressa. 



form ; eyes on peduncles at the 

 outer bases of the tentacles. 

 Mantle with a more or less elon- 

 gated siphon on the left side 

 in front; left gill rudimentary; 

 mantle cavity with a large pul- 

 monary sac on each side. Rec- 

 tum not traversing the heart. 

 Foot simple. Operculum annu- 

 lar, regular. Shell spiral, turbinate, covered with an oliva- 

 ceous epidermis; aperture simple in front. Jaws present. 



The AmpuUariidse are fluviatile, and represent in the ponds 

 and rivers of the tropics the VivijKiridae of more temperate 

 climates. Although distinct gills exist, the respiratory cavity 

 is very large and partly closed, so as to enable these animals 

 to live a long time out of water ; in fact, they appear to be 



( 1) 



Animal of Pomus depressa, reduced 

 one-half. 



