Synopsis Fresh-Watijr Moli^usca 23 



Subclass STREPTONEURA. 



Order PECTINIBRANCHIA. 



Suborder T.^NIOGLOSSA. 



Superfamily PLATYPODA. 



Key to the families of Platypoda. 



{ Operculum concentric 2. 



^■\ 



[ Operculum spiral 3. 



f Shell very large; animal with both gill and lung Av.ipuUarudcc. 



[ Shell smaller ; animal with gill only Vi-iApandiV. 



\ Operculum circular, multispiral .- . . Valvatidcc. 



[ Operculum paucispiral . 4. 



f Animal with external verge, central tooth with basal denti- 



4. \ cles Amnicolidcc. 



[ Animal without verge ; no basal denticles on central tooth 



Pleuroceridcc. 

 Family AMPULLARIID.E, 



Shell large, spiral, globosely turbinate; aperture entire; operculum (in 

 the North American species) corneus, concentric, with a sub-central nucleus. 



Animal with snout divided into two long, tentacular lobes ; tentacles long 

 and filiform ; eyes on peduncles on the outer bases of the tentacles ; mantle 

 with two cervical lobes, that on the left forming a more or less elongated 

 siphon ; genital orifices on the right side in the pallial cavity ; the respiratory 

 chamber divided into two parts, the one being a lung and the other contain- 

 ing a large gill; foot large, simple; jaws two; radula with seven rows of 

 teeth, central large, subtrapezoidal, multicuspid, no basal denticles ; the 

 laterals and marginal narrow, uni- or bicuspid. Oviparous. 



Genus AMPUELARIA Lamarck, 1799. 

 Shell dextral, globose, with a green or brown epidermis ; spire short, 

 last whorl rounded, inflated ; umbilicate ; 

 aperture entire, angular above, rounded 

 below, lip simple. 



4\{ 



Fig. 70 



Fig, 72 



