256 urn mm m. 



harbour more than one. Amphipeplea, as M. Philippi 

 correctly observes, bears the same relation to Limntea that 

 Physa does to Bulinus. 



Species of Amphipeplea. 



Cumingi, Pfeiff. Leucouensis, Eyd. 



glutiuosa, Mull. Strangei, Pfeiff. 



involuta, Harvey. 



Genus PHYSA, Draparnaud. 



Tentacles slender, setaceous. Mantle covering part of 

 the shell, the margin fringed or digitate. Foot long, 

 acuminate behind. 



Shell sinistral, oblong, thin, polished ; spire acute ; aper- 

 ture oval, rounded anteriorly, not dilated ; inner lip spread 

 over the last whorl, simple in front ; outer lip acute. 



Syn. Phyza, Risso. Anisus, Studer, not Fitz. Eivi- 

 cola, Fitz. 



Ex. P. fontinalis, Linnaeus, pi. 83, fig. 9. Shell, P. 

 fontinalis, fig. 9, a. 



In this genus the tentacles of the animal are slender and 

 filiform, and the edge of the mantle is extended over the 

 shell, and fringed or furnished with digitations ; the shells 

 may be recognised by their polished surface and sinistral 

 whorls. The Physce prefer clear running streams and 

 fountains ; they are extremely quick in their movements, 

 and are not readily intimidated. When kept in glass- vessels, 

 they may frequently be seen to poise themselves on their 

 loot, and rapidly vibrate their shells. They are found in 

 Europe, North America, South Africa, India, and the 



