LIMNJEADJE. 253 



(British Shells, t. 168. f. 2.), and Bulla fluviatilis 

 by Dr. Turton, in his Dictionary, p. 27. It is a 

 large specimen of this variety at fig. 11</. ; and others 

 with a rather longer spire, as if passing into the 

 next variety, that is figured by Lister, t. 134., by Da 

 Costa, t. 5. f. 6. 



The second variety, which is perhaps Physa sulo- 

 paca 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-3d the 

 length of the mouth, and formed of four or five dis- 

 tinct convex whorls ; and it -has a blunt top. 



This variety is called Physa rivalis by the York- 

 shire conchologists, but is quite distinct from the West 

 Indian species 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 spaceous specimen 

 I have examined, and the variation that I found in 

 the specimen sent to me under the two names, induce 

 me for the present to consider them as only variations 

 of the same, probably produced by some local situa- 

 tion, as the difference in the depth of the water, or its 

 being still or running. Mr. Hirich informs me, the first 

 variety is always found in very small plashes of water, 



