PHYSA. 
227 
It is a young shell of this variety that was most pro- 
bably figured by Donovan under the name of Helix 
bullceoides {British Shells^ t. 168. f. 2.), and of Bulla 
Jiuviatilis by Dr. Turton^ in his Dictionary, p. 27. 
It is a large specimen of this variety at fig. 110., 
and others with a rather longer spire, as if passing 
into the next variety, which are figured by Lister, 
t. 134., by Da Costa, t. 5. f. 6. 
The second variety, which is perhaps Physa sub- 
opaca of Lamarck, is a larger shell, often reaching 
3-8ths of an inch in length, which is most probably 
described by Montagu and Turton as the adult 
of the former variety ; for they say it sometimes 
reaches half an inch long. It is easily known from 
the former by the spire being produced about l-3rd 
the length of the mouth, and formed of four or five 
distinct convex whorls ; and it has a blunt top. In- 
deed, by the figures of Moquin-Tandon (t. 33. f. 1. 
16.), it is very doubtful if this variety may not be 
the P. acuta of Draparnaud. 
This variety is called Physa rivalis by the York- 
shire conchologists, but is quite distinct from the 
West Indian P. rivalis described by Dr. Maton. It 
is figured in Dr. Maton and Racket’s paper {Linn. 
Trans, xviii. t. 4. f. 1.) as Bulla fontinalis^ but does 
not agree with his description of the species, which 
certainly belongs to the first variety. This figure 
does not represent the inner lip sufficiently spread 
on the body whorl. The difference in the bluntness 
of the spire between the two varieties at first made 
me much inclined to consider them as species ; but 
the various specimens I have examined, and the 
