KEW : ON THE MUCUS-THREADS OF LAND-SLUGS. 99 



favourable ... it stops after having lowered itself a few inches. The body 

 is then slightly curved upwards; and after seeking for a while for a landing place, it 

 is coiled into a spiral form, from the centre of which the head is elevated along the 

 thread, and the position of the animal becomes reversed ; . . . the animal then 

 ascends with a tolerably even gyratory motion, the "slack" of the thread sometimes 

 accumulating below the tail. Having inverted a branch of a weeping ash tree with 

 several forks on it, into a flower pot, and by putting some of the slugs upon the 

 branches, I have never found any difficulty in getting them to descend, sometimes 

 as much as five or six feet. The slug which I have found to possess this power is 

 the small grey garden slug, particularly the whitey-brown, or yellowish-grey one 

 {Liiiiax a}-borit>ii). ... I have had as many as four suspended from a forked 

 branch at the same time, three of which returned a distince of five inches, and one 

 two inches, and all reached the branch, and crept along it again. They are very 

 apt to return shortly after they have commenced to descend. . . . To perform 

 the experiment of getting the slugs to do this, they should be collected the day before, 

 and kept under a glass shade, as the secretion is too thin to form a sufficiently strong 

 thread for their support if they are gorged with food. 



The sli]g referred to — certainly not L. arbonim — is doubtless Agr. 

 agresfis. I am indebted to Dr. Scharff for an opportunity of seeing 

 this paper. 



24. Tate, R. On the Land and Freshwater Mollusca of Nicaragua, 

 American Jown. Conch., vol. 5, 1870, p. 154. 



Agriolitnax americamis (Nicaragua) can suspend itself. The name 

 has been referred (with Agr. campestris, etc.) to Agr. Icevis. 



25. Tye, G. S. Molluscan Threads, AvV^r^ Gossip, 1874, p. 49-52. 

 A paper dealing with the mollusca generally; as regards slugs the 



author refers to Bouchard-Chantereaux, Reeve, etc. 



. . When a snail crawls (either a terrestrial or an aquatic species) it leaves 

 behind it a trail of mucus, which it discharges for the purpose of lubricating the foot 

 in its passage over any surface, and if the continuity of this mucus be not ruptured, 

 we have a thread in all respects analogous to those I am speaking of. 



This remark is noteworthy for the author was unacquainted with 

 Ferussac (7) who suggests the same fact. 



26. Harte, W. Molluscan Threads, Tom. cit., p. 117, 

 Harte calls attention to his paper (23): 



If, when it has descended some distance, say eight or ten inches, the 

 finger moistened with a slightly saline solution — say saliva — is applied to it beneath, 

 it deliberately turns itself up . . . and re -ascends by a steady motion . . . 

 If there is no projection of the edge of the branch to throw it off, it scarcely ever 

 fails to land upon the branch and return the way it came. . . . I do not believe 

 the thread is used as a means of voluntary descent, but that being frequently sub- 

 jected to the mishap of slipping off, they have acquired the power of recovering 

 themselves in this way, which they do so systematically as to leave no doubt about 

 its being a voluntary action enabling them to avoid descending into water, or 

 anything injurious. 



27. T., R. S. Slug-threads, Op. cit., 1875, P- ^9° = 



. . . In a greenhouse, from a vine-leaf which was within a few inches of the 

 glass and about four feet from the surface of the water in a tank, a slug was hanging 

 by a thread, which was more than four feet in length [?]... The thread, 



