1879.] NATURAL SCIENCES OF PHILADELPHIA. 19 



Judging from the number sent this is an abundant species. A 

 few years ago I received a large quantity from Tubuai, also one 

 of the Austral group, and nearly 100 miles east of Rurutu. That 

 group is, without doubt, its specific centre, or metropolis. 



The most surprising feature in the geographical distribution of 

 this species is its occurrence in three distinct groups of islands. 

 It is found, though sparingly, in nearly every valley in Tahiti, 

 which is over 300 miles from its metropolis. I also obtained it at 

 Mangaia, one of the Cook's or Hervey Islands, 400 miles west of 

 Rurutu. 



Had it only been detected in one or two valleys in Tahiti, its 

 introduction could have been attributed to human agency. But 

 when we consider its wide diffusion we can only account for its 

 presence either by a separate creation of the same species in three 

 groups of islands, or speculate on its distribution in some remote 

 period, when the three groups formed a single large island, or 

 part of a continent. 



After a careful comparison of many examples from the three 

 groups of islands, I cannot detect the slightest variation. Shells 

 from the same locality vary slightly in the length of the spire, in 

 size and thickness. 



It is a strictly arboreal species, and may be distinguished by 

 its uniform white color, flat, and widely-expanded peristome, and 

 gibbous columella lip. 



Reeve's figure is too much elongated. 



Stenogyra juncea, Gould. 



Bulimus junceus, Gould, Proc. Bost. Soc. 1846, p. 191 ; Ex. Shells, p. 



76, fig. 87 Pfeiffer, Mon. Hel. vol. II. p. 220. 

 Stenogyra upolensis, Mousson, Jour. d. Conch. I860, p. 175. 

 Bulimus upolensis, Pfeiffer, Mon. Hel. vol. VI. p. 100. 



This common species is very widely diffused through Polynesia. 

 I have found it inhabiting all the groups north of the equator, 

 and south at all the islands from the Marquesas and Paumotus to 

 the Viti group, and, in all probability, it ranges further west. 



They are found under loose stones, beneath decayed wood, and 

 among dead leaves, and range from near the seashore to 2000 or 

 more feet above sea-level. The animal is light yellow. 



Vertigo pediculus, Shuttleworth. 



Pupa pedieulus, Shutt.,Bern. Mitth. 1852, p. 296 Pfeiffer, Mon. Hel. 

 vol. III. p. 557 Mousson (Var. Samoensis), Jour, de Conch. 1865, 

 p. 175. 



