345 



NOTES ON THE FAMILY AMPULLARIID^, WITH LIST OF SPECIES, 

 VARIETIES, AND SYNONYMS, ALSO DESCRIPTIONS OF FOUR 

 NEW SPECIES. 



By G. B. SowEREY, F.L.S. 



Jiead IQth April, 1909. 



A CAREFUL study and comparison of the very numerous shells of this 

 family to which I have had access has resulted in the amalgamation 

 of a large numher of supposed species. Many of the forms to which 

 specific names have been given merge into others by almost im- 

 perceptible gradations, so that it is scarcely possible to define their 

 limits. Some of the characters which have been regarded as forming 

 important distinctions are found to be quite unreliable, such, for 

 instance, as the malleation of the surface. In several cases that have 

 come under my notice in specimens unquestionably belonging to 

 the same species, some are strongly malleated, others only slightly 

 so, and others are perfectly smooth. The umbilicus is also an 

 unreliable character ; Ampullaria impervia (Philippi), for instance, 

 is more often umbilicated than not. In the following list I have 

 placed provisionally as separate species some forms which would 

 very likely unite with others, were a sufficient series under view to 

 show the connexion, and in some cases the actual shells are unknown 

 to me, so it is best to assume tiiat a species is good until it can be 

 proved bad. This work is therefore of necessity incomplete. 



The present paper treats only of the species of the Western Hemi- 

 sphere — Ampullaria (sensu stricto), Ceratodes, and Pomella. In a 

 subsequent contribution I hope to treat of the Eastern forms — Pila, 

 Lanistes, etc., and to take the opportunity of making an 3- needful 

 additions to or alterations in my present list. 



Genus AMPULLARIA, Lamarck. 



Ampullaria, Lam., 1799, Prodrome, p. 76 [ex parte). 



Ampullaria, Lam., Systerae, Animaux sans Yertebres. 



Ampiillarius, Montfort, Conch. Syst., 1810, vol. ii, p. 242. 



Pomacea, Perry, Conch. Expl., 1811, pi. xxviii. 



Marisa, Gray, Phil. Mag., 1824, vol. Ixiii, p. 276. 



Pomus, H. & A. Adams, Genera Rec. Moll., 1854, vol. i, p. 346. 



Type. — Ampullaria urceus, Miiller. 



Note. — Lamarck's diagnosis of the genus describes the operculum 

 as ' corne ' (horny). This does not apply to the species usually 

 regarded as the type, viz. A. ampullacea {Helix ampullacea, Linn.), 

 but only to the species of the Western Hemisphere, all of which have 

 horny opercula, while those of all the Eastern forms are more or 

 less testaceous, with the exception of the sinistral African species 

 distinguished under the generic names of Lanistes and Meladomus. 



VOL. VIII. — SEPTEMBER, 1909. 27 



