250 PROCEEDINGS OF THE MALACOLOGICAL SOCIETY. 



Hahits and JEcotiomi/. — The habits and mode of life, the food and 

 general economy of the genus have been very imperfectly studied. 

 It would seem incredible, were it not the fact, that although scores 

 of fine and handsome species of Clausilia, from e.g. Japan, China, 

 and Tongking, have been discovered and named, scarcely a single 

 word has ever been written on the conditions of life under which 

 even one of them exists. Over fifty species of Nenia have been 

 described from South America ; all that is known of their life is that 

 one species (steeriana, Sykes) lives "on the plains, under stones", 

 and another {pampasensis, Dall) "on cactus and mimosa trees". 

 It may be hoped that a time is coming when it will be regarded as 

 a sound contribution to scientific knowledge to accumulate facts 

 bearing on the life-history of the Mollusca. 



Some groups, Alopia for instance, are found exclusively on limestone 

 rock, and not on all limestone, but only on limestone of a particular 

 formation. Medora and Agathylla are also rock-loving groups, but 

 while Alopia is extremely partial to shade, and rarely ventures into 

 the sunlight, many species of Medora, Agathylla, and Alhinaria hang 

 their white or blue-grey shells in tlie full rays of the sun. The group 

 Marpessa, smooth and lustrous shells, to which our own laininata, 

 Mont., belongs, lives on smooth tree-trunks, such as the beech, ash, 

 and sycamore, and I have observed, in the Carpathian forests, that 

 such Marpessa as orthostoma, Menke, and margmata, Zgl., prefer the 

 trunks of young trees, and seldom occur on old ones. Although the 

 forests of Transylvania often grow right up to the face of a cliff, on 

 which Alopia may be swarming in liundreds, you will never find an 

 Alopia on the trees, nor a Marpessa on the cliffs. The reason is, that 

 the Alopia (\.Q\o\\Y the decomposed surface of the limestone, on which 

 they find some minute vegetable food, while Marpessa and other tree- 

 loving groups find their nutriment on the equally minute organisms 

 which grow on the bark, or in the mosses which gather in the cracks 

 of the trunks. Pine-trees are seldom climbed by Clausilia, the 

 resinous nature of the bark probably being disliked, but I have 

 noticed a Pseudalinda {cana, Held) and a Pirostoma {duiia, Drap., 

 var.) quite exceptionally on pine-trees 6 feet from the ground. 



Again, some species are ground-loving, and seldom venture off the 

 level. Such is our own Pirostoma rolphii (Gray), but we must not 

 conclude that all Pirostoma are ground-loving ; on the contrary, 

 plicatnla, Drap., and parvnla, Stud., live habitually on rocks and trees. 

 PJuxina mossta, Fer., near Eeirut, buries itself among loose stones and 

 earth to a depth of several inches, but probably not all Euxina have 

 this habit, although a ?.\)eQ,ie?>{corpale7ita, Friv.) I met with atBrussa 

 in Asia Minor lives habitually on banks at the roots of grass. A species 

 of Pseudalinda [fallax, Rossm.), common in the East of Europe, is also 

 a ground-loving shell, living at the roots of bushes and nettles, often 

 under layers of dead leaves, on which it feeds, and seldom mounting 

 rocks. A tiny Graciliaria {filograna, Zgl.) conceals itself under dead 

 leaves and in cracks on the ground. One notices that species which 

 crawl on the ground and do not hang suspended are often of corpulent 

 habit, while many species which hang are narrow and produced : 



