40 JOURNAL OF C0NCH0L0(;Y, vol. II, NO. 2, APRIL, I904. 



(9) P. complanatus L. sp. — "Syst. Nat," Ed. X., 1758, vol I., 

 p. 769 {Helix) ; Miiller, "Verm. Hist.," 11., 1774, p. 160 {P. uvibili- 

 catus); Drap., "Hist. Moll., p. 45, t. ii., f. 11, 12, 15 {P. marginahis) , 

 Costa, "Catal. test, due Sicilie, 1829, p. cvii., nr. 36, pars {^Helix 

 carinatd) \ Phil., "Moll. Sic, I., p. 145; H., p. 119 {P. marginatus). 

 The most common species of Planorbis with us, abounding in stagnant 

 waters and rivulets in numerous colonies. 



P. complanatus is common in the Mediterranean littoral, Europe 

 and Siberia, and frequently varies. The type must have the inferior 

 keel and it is allied to the following species, from which it is 

 distinguished by the thickness and less compression of the last whorl. 

 The shell is always incrusted by vegetal organisms which conceal 

 its color. 



Var. submarginatus De Crist, et Jan. — "Catal.," 187 1, XX., 

 n. 9, 12. Less common. 



(10) P. carinatus Miiller. — "Verm. Hist," 1774, H., p. 157 {non 

 Studer). More common and localised than the preceding, with which 

 it lives together, also thinner and more pellucid than P. complanatus 

 and with the keel central. 



The last two forms of Planorbis are united by the variety submar- 

 ginatus. The keel is inferior in P. complanatus^ central in P. carinatus 

 and occupies an intermediate situation in the above-mentioned variety. 



(11) P. subang-ulatus Phil.— "En. Moll. Sic," H., 1844, p. 119- 

 t. xxi., f. 6; Bourg., "Malac Algerie, 1864, p. 153, t. ix., f. 27-30; 

 Locard, "Conch. Portugaise," 1899, p. 179. In company with the 

 other species. The original locality cited by Philippi is "in rivulis 

 prope Panormum frequens." 



I have never found Planorbis corneus near Naples, though Philippi 

 has seen it (I., p. 146); but his citation is not confirmed in the second 

 volume of his work. 



Physid^e. 



(12) Physa contorta Mich. — Bull. Sac Linn. Bordeaux, 1829, 

 t 3^- p. 268, f. 15-16 ; Phil, "Moll. Sic," I., p. 47, t ix., f. i {P. 



rivularis), H., p. 120 {P. contorta'). In small clear waters. 



(13) P. fontinalis L. sp. — "Syst Nat.," Ed. X., 1758, vol. i., p. 

 12-] {Bulla) ; MiilL, "Verm. Hist," II., p. 165 {Planorbis bulla); 

 Costa, "Catal. test, due Sic," 1829, p. cvii., nr. 37 {Bulla f.) ; Phil., 

 " Moll. Sic," II., p. 1 20. In clear waters on the plants. This species, 

 living in Southern Europe and the Canary Islands (Webb & Berthelot), 

 is allied to P. co/itorta, a distinctly southern form, but the shell is less 

 swollen. 



