292 THE ZOOLOGIST. 



These little Snails, as far as the writer has ascertained, are the 

 only Helicoid-shelled molluscs known to make threads ; the 

 Trochonanina conula was collected by Garrett from foliage of 

 bushes in the Cook's or Harvey Islands, and in the Society 

 Islands. 



PUPIDyE. 



There is a statement in Mr. Tye's " Molluscan Threads " 

 (1878) that Mr. Dixon, of Leeds, " has seen several individuals 

 of Clausilia rugosa var. dubia suspended."* A number of Clau- 

 silia rugosa kept by the present writer for a considerable time in 

 glass vessels, with twigs, &c, were not seen, however, to use a 

 thread ; and, as indicated above, two other species of Clausilia 

 have been experimented with on twigs of needle-furze with similar 

 negative results. Clausilia rugosa, it is true, was sometimes 

 seen hanging during rest by a point of dried mucus, attaching 

 the lip of the shell to the object of support, and allowing the 

 creature to swing freely ; but this, apparently, was merely the 

 result of the breaking away or failure of the greater part of the 

 film by which resting Clausilice ordinarily fix the mouth of the 

 shell ; a method of attachment familiar to us in the common 

 Snails {Helix, &c). In Helix (and probably in Clausilia also) 

 the mucus of this attachment comes, not from the foot, but from 

 the mantle. On inquiring of Mr. Dixon, in 1893, the writer 

 found that the observation on Clausilia had passed from his 

 memory ; he stated, however, that he had seen Balea perversa, in 

 the Isle of Man, suspended by a string of mucus about an inch 

 long from the under side of stone ledges ; he supposed that the 

 animals, in crawling over the ledges, had overbalanced, and that 

 their mucus, more glutinous than usual owing to the dry weather 

 prevailing at the time, had held them suspended, and had been 

 gradually drawn out by the weight of the mollusc. 



LlMN^ID^E. 



The air-breathing fresh-water Snails of this and the next 

 family are notorious spinners, the habit being associated with 

 the visits to the surface of the water which most of these 

 creatures are compelled to make from time to time for the pur- 

 poses of respiration. Most of them have light shells, and when 

 * Tye, ' Quarterly Journal of Conchology,' i. (1878), p. 412. 



