BELLINI : FRESHWATER SHELLS OF NAPLES AND NEIGHBOURHOOD. 37 



Var. margaritacea A. Costa. — -"Statist, fisica deH'isola di 

 Capri," 1840, p. 65; Bellini, "I moll, extramar, dell'isola di Capri," 

 1900, p. 52. Very rare variety, in a fountain called "marroncella" 

 (Capri). We may consider this form as a local modiiication of the 

 type, from which it differs in the sinuosity of the anterior margin, 

 while the shell is internally pearly. The author thinks A. margaritaceus 

 to be allied to A. sifiuahis Brard, a synonym of A. simplex, a variety 

 of A. fluviatilis. 



Bourguignat^ admits in Europe 35 species of Ancylus; but we 

 believe that only two live in Central and Southern Europe — A. 

 fluviatilis and A. laciistris. The first constitutes the type of the sub- 

 genus Ancylastrum Moq.-Tand., 1853 (summit of the shell inclined 

 to the right), the second, the subgenus Velletia Gray, 1840 (summit 

 of the shell inclined towards the left). This last is of eocene origin, 

 and more ancient than the first, which appears in the miocene. 



(2) Limnaea stagnalis L. sp. — "Syst. Nat.," Ed. X., 1758. I., 

 p. 774 {Helix); Costa, "Catal. test, due Sicilie," 1829, p. cvii., nr. 38; 

 Phil., "Moll. Sic," II., 1844, p. 120. Not very abundant and 

 dispersed in small deep waters (Sebeto, lake of Astroni, etc.). 



The type of this species has been the origin of many discussions; 

 according to Bourguignaf- the type lives in the Danube, near Belgrade, 

 and is common in Sweden, Denmark, Germany, rarer in France, Italy, 

 and Russia. But Locard'' admits as type the figure given by 

 Kobelt in his monograph of European Liinncece,^ agreeing with the 

 Linnean type and with figures of Lister and Gualtieri. 



(3)L. palustris Miill. sp.— "Verm. Hist.," II., 1774, p. 131, n. 

 326 {Bucciniuii) ; Costa, "Catal. test, due Sicilie," 1829, p. cvii. 

 {Helix); Phil., "Moll. Sic," I., 1836, p. 146; II., p. 120, 1844. 

 In numerous colonies (Paludi, Sebeto, Astroni, Botanical Garden). 

 Smaller and less swollen than the preceding species. Type and 

 varieties very common. 



Var. corvus Gmelin. — "Syst. Nat.," Ed. 13, 1778, p. 3665 

 {Helix) ; Drap., "Tabl. Moll.," 1805, pi. II., f. 40-41 {Helix palustris 

 var. major) ; Phil., "Moll. Sic, I., 1836, p. 146 (var. a). Shell of 

 large size, violaceous internally. 



Var. fusca Pfeiffer. — " Deutsch. Moll.," 1829, I., p. 92, t. iv., f 

 25. Smaller than the type, but more swollen. 



Var. elongata Locard. — "Etud. sur les variat. malac," I., 1881, 

 P- 337- Spire elevated, low aperture and deep suture. 



1 '"Etude synonimique sur le genre Ancylus," Spic. Malac. ^ p. 139. 



2 Sfiic. Jllalacol., 1862, p. 96. 



3 " Etudes sur les variation des moUusques," iii., I., p. 339. 



4 MalakozooL Bldit., p. t68, t. ii., f. i, 1871. 



