2IO JOURNAL OF CONCTIOT^OOY, VOL. lO, NO. 7, JULY, I902. 



continent, but the nearest affinity is evidently to tliat of the widely 

 spread genus Partida^ to whose longer forms many of the smaller 

 Placostyli approach very closely. 



The forms belonging to Placosiylns are distributed by Albert and 

 von Martens over three different subsections. Placostylus with the 

 type Bui. fihratiis Martyn, Eumecostyhis with the type Bui. cleryi 

 Petit, including as a subspecies {Aspastu%) the beautiful Bui. mil- 

 tocheilus Reeve, and Charts with the type Bui. malleatus Jay. The 

 numerous recent discoveries have effaced the boundary between 

 Placostylus and Eumecostyhis. Charis is, however, divided from both 

 not only by its thinner shell and the deviating markings, but more 

 particularly by its mode of living. All kinds of Charis live on trees 

 and shrubs, whilst the genuine Placostyli never leave the ground. 

 Buliinus viiltocheilus, which is also arboreal, still stands quite isolated, 

 and must be yet maintained as a separate subspecies. 



In New Caledonia thelarger/Vtr^-^^i-Zj// formed, until the introduction 

 of the European domestic animals, a very important source of food 

 for the natives. They are still eaten up to the present time, and also 

 French settlers have become familiarized to them as food. 



The grouping of these Placostyli is much more difficult than any 

 other section of Bulimus. The development of the tooth on the 

 mouth-wall of the connection callus, and also of the mouth seam, and 

 even of the columellar fold apparently depends on the age of the 

 animal, the thickening continuing to go on, even in the mature shell, 

 and may attain ultimately such a high degree that the columellar fold 

 disappears, whilst on the other hand, some shells exist, which appear 

 quite complete with feeble wall-callus and quite toothless. Under 

 unfavorable circumstances, such as want of food, and especially want 

 of lime, or in dry places, the thickening may remain trifling and thus we 

 get in many species local varieties with thinner shells, feeble mouth 

 seam and with a just noticeable tooth, or even without tooth. 



But also the colouring is an extremely variable one, especially that 

 ot the mouth, and side by side there are forms with dark brown or 

 brilliantly orange coloured gums and richly coloured mouths, along 

 with many species with pale yellow gums and purely white mouth 

 edges. Lastly the Placostyli, as all large snails, are exposed to many 

 injuries and therefore inclined to the development of individual 

 abnormalities, which form sometimes a quite differing exterior, and 

 may easily lead to the establishment of new varieties. 



The geographical area of the various species is mostly a very limited 

 one, only a few are spread over various islands, and those always on 

 islands quite close to one another. None that exist in one archipelago 

 will be found in another. Most of them are limited to one island, 

 many only to part of an island. For the Placostyli that live on the 



