FAMILY LYMNiEACEA. 149 



quite horizontally. Its geographical range is not very clearly esta- 

 blished. It is not uncommon among duckweed and dead leaves 

 in the neighbourhood of London ; and it is recorded as having been 

 collected in Ireland and in the south of Scotland. On the Conti- 

 nent it does not appear to have been noticed south of the Pyrenees. 

 Central Europe seems to be its chief area of habitation, and it is 

 said to have been collected in Sweden. 



Physa foiitinahs. 



Genus II. PHYSA, Draparnaud. 



Animal ; body ocellated, carrying a transparent sinistrally coiled 

 shell, over the edge of which the mantle is sometimes reflected, 

 fringed with digitate lobes, foot lanceolate and pointed behind , 

 obtuse in front, yellow, clouded more or less with very minute 

 dusky specks, head rather truncate, furnished with two con- 

 tractile fiHform tentacles which are broad at their base, at the 

 inner corner of each base are situated the eyes, black and con- 

 spicuous. 

 Shell ; sinistral, ovate and ventricose or fusiformly oblong, trans- 

 parent, glassy, of four whorls with the spire short, or of five 

 whorls with the spire attenuated ; aperture ovate, Up simple, 

 columella thinly callously twisted. 

 This pretty mollusk, with its ocellated colouring seen through a 

 transparent sinistrally convoluted sheU, and with its curiously digi- 

 tate fringe-lobed mantle, is the European representative of a genus 

 belonging more especially to Australia and Central America. In 

 Australia and New Zealand, some thirty species of Physa have 

 been collected, many of them covered with an epidermis and of 



