recent shells. 195 
Lymnzxana, Second Family. 
There are some species here of all the genera belonging 
to this family. 
Planorbis, 
** Shell discoidal, all the whorls visible on both sides ; a- 
pertare distant from the axis of the shell ; margins not re- 
flected. They are fresh water animals, have two tentacula 
with eyes at their base.” 
Planorbis spirorbis, ‘‘one side flat, the other subumbelicat- 
ed, reverse ; horn coloured,’’ 
Found in abundance in the water near Etchemin. 
Planorbis alba? ‘* Shell umbelicated on both sides; upper 
part of whorls flat, lower convex ; aperture wide and apgue 
lar."” 
Found with the foregoing, but not so common, it is the 
Helix alba of Linnzus, but is not among DeLamarcks species. 
Physa. 
“Shell convolute, oval or oblong; spire projecting; aperture 
longitudinal, contracted above; columella twisted, right 
margin acute projecting beyond the plane of the aperture.” 
They are fresh water animals; have two flattened tentacu- 
la with two eyes at their base. 
** Physa fontfnalis, reverse, oval, transparent smooth, 
horn coloured: spire short, subacute.” 
Not very common, but is sometimes met with on the beach 
at the Island of Orleans. 
Physa subopaca. ‘Shell reverse, oval, semipellucid, 
grayish yellow ; epire short, acute.” 
This species is rather more common than the foregoing, 
they are offen found together at the Island ; it resembles fon- 
tenalis, but is not so transparent. It is yellow without, and 
white within. 
The third and Jast geuus of this family is 
Lymhwa 
