100 



after floating, if there is no leaf or stalk near it. Leach 

 says that when it is annoyed by the approach of wander- 

 ing animals, it repulses them with repeated blows, in- 

 flicted by a rapid movement of the shell ; the foot being 

 the point of fixture. This species was first described 

 and figured by Lister. 



The shell is more ventricose than that of the last spe- 

 cies; and it has a much shorter spire and a larger 

 mouth. 



The Bulla rivalis of Maton and Rackett, which was 

 supposed to have been found in Hampshire, is a common 

 West-Indian species, which now bears that name. It is 

 the P. Sowerbyana of D'Orbigny. 



Mr. Choules has described in the l Zoologist ' a species 

 of Physa which he found in a water-tank in Kew Gar- 

 dens, and which Mr. Norman (being misinformed as to 

 the precise locality) has proposed to admit into our 

 native Fauna. It appears to be a variety of the P. acuta 

 of Draparnaud, but it is undistinguishable from speci- 

 mens in the British Museum which were collected in 

 Cuba, St. Thomas, and St. Croix ; and it has probably 

 been introduced with some aquatic tropical plant. Dr. 

 Hooker informs me that many West-Indian plants have 

 been imported and cultivated in the Gardens. P. acuta 

 has never (so far as I am aware) been found in this 

 country; and although it is abundant in the middle 

 and South of France, it has not been recorded as inha- 

 biting any of the northern Departments. The P. sub- 

 opaca of Lamarck is a variety of that species. 



The P. alba of Turton, who stated that he had received 

 it from Capt. Blomer as a native of Towyn in North 

 Wales, is the P. contorta of Michaud, and is only known 

 to inhabit the Eastern Pyrenees, Corsica, Sicily, and 

 Algeria. 



