Quarterly Journal of Conchology. 409 



Physa fo7itinaIis stands next as a thread-spinner, using the 

 thread in a similar manner but not so often, 



Limncea glabra, although not using this means of locomotion 

 so often, nevertheless spins well and easily. 



Z. stagnalis is active when young, but its habit of spinning 

 decreases as it grows older. 



L. paliistris. — The same remarks apply to this species also, 

 although I have not seen it spin so commonly as stagnalis. 



L. peregra. — This species has been observed to spin by my 

 friend Mr. R. M. Lloyd, but it very seldom uses a thread. 



Z. gluiinosa, recorded as a thread-spinner by Mr. Warington. 



Planorbis complanatus, P. spirorbi's, P. contortus. — These species 

 spin very much less often than the foregoing. 



Some species of Cerithidea inhabiting salt marshes and Man- 

 grove Swamps suspend themselves by a number of glutinous 

 threads out of the water, e.g., C. decollata,'^ L., Borneo. 



Mr. Thomas Hoyf seems to have been one of the earliest 

 observers of this method of travelling as practised by the slugs, 

 and he has given an account of one he saw hanging from a Pine 

 tree by a filament four feet long, and travelling towards the earth 

 at the rate of one inch in three minutes. At the Scime time Dr. 

 Shaw gives an instance (from a memorandum made in 1776) of a 

 slug descending from the roof of an arbor, the extraordinary dis- 

 tance of eight feet, until it nearly touched the ground, when he 

 shook it off. 



Limax arbonnn. — M. Bouchard-Chantereux has seen young 

 individuals of this species descend from branch to branch of a tree 

 by a mucous filament, and he supposes this species to be the 

 Limax filans., or spinning slug of some English authors of the 



* Woodward, "Manuel of Mollusca," p. 243, 1868. 

 t Trans. Linnean Soc, vol. i, p. 183 et seq. 



