THE 



CONCHOLOGICAL MAGAZINE 



Vol. II August, igoS No. 8 



TWO GENERA OF LAND SNAILS NEW TO 

 JAPAN AND KOREA 



By HENRY A. PILSBRY. 



The genus Strobilops is characteristic of North America, where 

 some half dozen species are found, extending from the Canadian zone 

 to as far south as Venezuela, the best known being 5. labyrinthica 

 (Say) and S. hubbardi (A.D.B.). 



As living snails, Strobilops is unknown in Europe ; but the 

 Eocene, Oligocene and Miocene deposits contain many fossil species, 

 most of them originally described as Helix. 



The only Asiatic species described is Strobilops diodoritina 

 (Heude),* from Tchen-keou. A second species has now been found 

 on Cheju Island (Quelpart), Korea. These species supply a con- 

 necting link geographically between the fossil species of the European 

 Tertiary and the recent forms of America, and lend probability to 

 the idea that the original migration from continent to continent passed 

 over a former land-bridge now covered bv Bering Sea. 



Strobilops hirasei a. sp. Fig. i. 



The shell is narrowly umbilicate, low conic, the outlines of the 

 spire convex, the last whorl indistinctly subangular at the periphery, 

 convex at the base. Surface brown, slightly shining, nearly smooth, 

 sculptured with fine growth-lines only. Whorls nearly 5 y, convex, 

 very narrow and slowly increasing. The aperture is oblique and 

 lunate. Peristome brown, well expanded, thickened within. Two 

 lamella? on the parietal wall emerge, the outer one very strong and 

 high, the inner low and inconspicuous. These lamella; penetrate 

 inward about one-third of a whorl and diminish rather suddenly at 



* Helix diodoniina Heude, Notes sur les Mollusques terrestres de lavallee du Fleuve 

 Bleu, in Memoires concernant l'histoire naturelle de l'empire Chinois, vol. i p if pi 

 29, fig. 11. 



