290 SPECIES OF THE SAME GENUS 



Of the first of these classes the genus Auricula, as defined 

 by Lamarck, may be quoted as a striking example. Of its 

 species, A. scarabus and A. minima are found in damp 

 places on the surface of the earth ; A. judae lives in sandy 

 places overflowed by the sea ; A. myosotis, A. coniformis, 

 A. nitens, &c. (separated by De Montfort under the name 

 of Conovulus,) are found only in the sea in company with 

 Chitons, Littorinae, and other truly marine shells ; and the 

 South American species which I distinguished some time 

 since under the name of Chilina, including A. Dombeyi of 

 Lamarck, and A. fluviatilis of Lesson, inhabit freshwater 

 streams, having most of the habits of the Lymnaeag. This 

 disparity of habitation has been in some degree overcome by 

 dividing the genus into several, as noticed above ; but the 

 characters employed for their distinction are very slight, and 

 species apparently intermediate between them are constantly 

 occurring. 



The genus Lymnaea has usually been considered as con- 

 fined to fresh water; but M. Nilsson describes a species 

 under the name of L. balthica, which is found "in aqua, 

 pariim salsa Maris Balthici ad littora Gothlandiae et Scaniae, 

 &c. In maris juxta Esperbd fucis et lapidibus adhaerens 

 frequenter obvenit simul cum Paludina balthica et Neritina 

 fluviatili ;" and a second under the name of Lymnaea suc- 

 cinea, which is found on the shores of the sea near Trelle- 

 borg. All the species of Paludina and By thynia which have 

 fallen under my own observation are essentially fluviatile ; 

 but M. Nilsson refers in the paragraph above quoted to a 

 species of the former genus inhabiting the sea. This may, 

 however, like some of the smaller Paludinae of Draparnauld, 

 be truly a Littorina, having a horny and spiral, and not an 

 annular operculum. 



According to the observations of my sister, Mrs. Ince, of 

 Mr. Benson, of MM. Quoy and Gaimard, and of M. Lesson, 

 the Indian species of Neritina, like the European, are found 

 only in fresh water ; yet M. Rang, in his Manuel des Mol- 

 lusques, p. 198, states that the Neritina viridis is a marine 

 species found on rocks covered by the sea at Martinique, 

 and that a larger variety of this species is found in similar 

 situations at Madagascar ; General Hardwicke marks on his 

 drawing of the Neritina crepidularis, that it was found in 

 "saltwater lakes, April 1816;" and Say has described the 

 Neritina meleagris of Lamarck (Theodoxus reclinatus, Say), 

 as living both in fresh and salt water. This is most pro- 

 bably the species to which Mr. Guilding refers,* when he 



* See Zoological Journal, vol. v. p. 33. 



