121 



The animal possesses two lengthy tentacles. The 

 foot is lanceolate. 



Professor Forbes remarks, in the British Molluscat 

 that fossil Physoe, closely resembling our present 

 species, are abundant in Dorsetshire, in the Purbeck 

 strata. 



Physa FONTiNALis [The Stream Bubble Shell]. 



LinneBus. 



Figure 87. 



87. 



Physa fortinalis is the Bulla fontinalis of Linnaeus. 

 It is usually ovate, with a short spire, ending in an 

 abrupt and blunt apex. Nearly pellucid, shining, very 

 thin, and fragile. Colour amber to pale horn. There 

 are four to five convex convolutions, the body whorl oc- 

 cupying nearly the whole of the shell. Aperture large, 

 with the edge not reflexed. The pillar white. 



First described by Lister, in the year 1678. 



There are several varieties of this shell, very distinct; 

 it is possible that it may yet be cfivided into three 

 species. Of these one variety is rare : the spire is con- 

 siderably more produced. I have never met with it. 



Another variety, acuta, is procured in one locality, 

 near Lenton. It has several marked characters, so dis- 

 tinct from the ordinary form of Physa fontinalis that it 



