396 THE TEKRESTRIAL MOLLUSCA INHABITING 



Huahine. The spire is more robust than in either of those species, and in that 

 respect makes a nearer approach to the Tougan suhgonochila, which is smaller and 

 more solid. 



P. HYALINA, Broderip. 



Partula hyalina, Brod., Proc. Zool. Soc, 1832, p. 32. Muller, Syn., p. 32. Reeve, Conch. Syst., 

 ii., PI. 115, figs. 1-2. Jay, Cat. Shells (1839), p. 51. Reeve, Conch. Icon., PI. 3, fig. 14, 

 PfeiflTer, Mon. Hel., iii. p. 451; iv. p. 510; vi. p. 159; viii. p. 198. Pease, Proc. Zool. Soc, 

 1811, p. 413. Paetel, Cat. Conch., p. 104. Schmeltz, Cat. Mus. Godeflf., v. p. 92. Garrett, 

 Proc. Phil. Acad. Nat. Sci., 1819, p. 18. 



Bulinus hyalinus, Sow., Conch. 111., fig. 9. 



Bulimus hyalinus, Lam., Ed. Desh., p. 284. Pfeiffer, Mon. Hel., ii. p. 61. • 



Partutus hyalinus, Beck, Ind., p. 51. 



This well-known species, which has its metropolis or specific centre in the 

 Austral Islands, also inhabits Mangaia four hundred miles west of the former 

 group. It is also distributed in limited numbers in every valley on Tahiti, which 

 is three hundred miles north of its metropolis. 



With the exception of the AuricuUdce, it is the onli/ species of Polynesian land 

 shells of its size common to two or three distant groups of islands. 



As the above statement does not harmonize with the distribution of the various 

 species of Polynesian shells as recorded by different authors, I will add, that in Dr. 

 Pfeiifer's last volume of his " Monographia Heliciorum," where he enumerates 

 • seventy-seven species of Polynesian (I exclude the Melanesian and Pelew species) 

 Partula, there exist twenty-six errors in localities, or a fraction less than one- 

 third!! In Peeve's Monograph of the same genus, where he records twenty-five 

 species, there are seven wrong localities. 



In Paetel's Catalogue of fifty-one species of Partula, over one-fourth of the locali- 

 ties are erroneous. In Mr. Pease's list of Polynesian land shells, where he enu- 

 merates sixty-five species, including his two Btilimi, there are eight wrong habitats 

 given. 



All the species, which are diffused over one or more groups, are invariably 

 minute shells. The same law obtains in the distribution of the minute species of 

 Europe and North America, some of which extend their range over large portions 

 of the three continents, and have even migrated into the tropics. 



This solitary exception to the general law which governs the distribution of 

 the larger species in Polynesia, is the more remarkable from the fact that the two 

 remote islands where it occurs are the ones nearest to its metropolis, and the 

 species has not spread to any of the neighboring islands in either group. 



