COOKE : THE HABITAT OF CLAUSILI^. 143 



open face of tlie cliffs, in spots where a slight trickle of water kept the 

 great smooth slabs perpetually moist. This was its regular habitat, 

 though now and then an individual might be found in the dry. 

 A variety, major, was afterwards detected in a somewhat similar 

 habitat at Duare. Associated with it at Almissa was another species 

 not half the size, as yet unidentified, but belonging to the Cattaroensis 

 group. This species only occupied the cracks, or nestled under the 

 ledges, while Almissana paraded about boldly in the open, a most 

 conspicuous object. 



At Ragusa I found several species, each under circumstances 

 peculiarly its own. CI. exarata, Zieg., lives on hollow damp limestone 

 rocks, not merely gregariously, but under circumstances which suggest 

 extreme overcrowding. I must have taken from 10 to 15 individuals, 

 several times over, from one small hole in the rock. And this tight 

 packing was not due to scarcity of suitable domicile, for there were 

 quantities of similar holes quite unoccupied ; they evidently loved to 

 squeeze closer together than I have ever seen Clausilia live. At the 

 island of Lacroma a more slender form of the same species occurred 

 in cracks of rocks which hung over the sea. It was quite a new 

 sensation, gathering Clausilia with one's feet in the sea-water. At 

 Lacroma also Cattaroensis occurred, in complete contrast to exarata, in 

 single and solitary specimens on a damp old wall. 



An expedition to the source of the Ombla, behind Gravosa, taught 

 me a fresh lesson about Clausilia. Por I knew there must be a species 

 there, but though I looked on walls, in cracks, in damp places, under 

 herbage growing on rocks, I could find nothing. At last a happy 

 accident revealed to me the fact that celestina, Kiist., cares for none of 

 these places, but hangs on bare and very dry rock faces, provided only 

 they do not look full south. Its colour greatly resembles that of the 

 rock. When I grasped this fact I found them in dozens, never 

 crowding together like exarata, nor at long distances apart like 

 Cattaroensis, but evenly and abundantly distributed over the whole 

 rock surface. 



After an expedition to Castelnuovo, on the Bocche di Cattaro, which 

 was fruitless as regards Clausilia, but which yielded a few specimens 

 of the fine Pomatias auritus, I came through Mostar, the capital of 

 Herzegovina, to Jablanica, at the head of the great Narenta defile, 

 hoping for rich booty. Never was I more disappointed. The rocks were 

 of that soft disintegrated slaty type which never yields anything, and 

 complete failure seemed imminent. I argued, however, that if I went 

 back to where the defile narrows sharply (Jablanica is on a marked 

 widening out of the valley) I should get upon the harder limestone 

 again, with a better chance of success. For a long time this plan 

 was without result, but it was again a case of looking in the wrong 

 place. For, this time, it was not the limestone slabs or crannies 

 themselves, but a peculiar band of conglomerate running through the 

 limestone near Prenj, that furnished CI. albocincia, Pfr., in considerable 

 numbers. A vein of clay ran in and out of the conglomerate, and 

 on this, apparently a most unpromising locality, the species clung in 

 quantity. What its food could be puzzled me at the time, for there 



