LAND SNAILS. 
179 
twelve transverse rows, containing fifty-one 
teeth; the central tootli is short and rounded; 
the laterals at first are similar to the central 
tooth, hut gradually merge into the nncini, 
which are short and bidentated. 
The species varies considerably in size, colour, 
and length of spire, and number of teeth. A 
persistent variety is 0 . myosotis (PI. XI., fig. 137); 
the shell is much thicker, and wants the tooth¬ 
like protuberances on the outer lip ; it is a fossil 
of the Red Crag at Sutton, and of the Mamma- 
liferous Crag at Bramerton, associated with an 
extinct species, 0. pyramidalis. 
0 . denticulatus inhabits brackish marshes, or 
lives under stones immediately above high-water- 
mark, near the mouths of rivers, often in com¬ 
pany with Hydrobia ulvce. It also frequents the 
rejectamenta of rivers, feeding on the cast-up 
matter. The animal is active and irritable; it 
does not hibernate. Twelve eggs, or so, united 
into a common mass by a viscid material, are 
deposited among stones; they are hatched at the 
end of a fortnight, and the young attain the adult 
state in about a year. 
The species is confined to the south and west 
shores of England, and is rare in Ireland. It is 
found in the interstices of a sea-wall in Portland 
Harbour, Maine. 
Conovulus bidentatus —{the Two-toothed Cono- 
N 2 
