KEW : ON THE MUCUS-THREADS OF LAND-SLUGS. 97 



16. Clarke, B. J. On the species of the genus Limax occurring in 

 Ireland, Ann. &= Mag. Nat. Hist, vol. 12, 1843, P- 34i- 



The young of all our British species "have the power of using a 

 thread until they attain that size when the weight of their bodies be- 

 comes too great "; they then invariably fall when the tail approaches 

 the edge of the object from which they allowed themselves to slide. 

 The author had made the following species spin: L. arhorutn 

 (young), Anialia sowerbyi (young), Agr. agrestis (young and adult), 

 Avion -hortensis (young and adult), and A. ater (young only). 



17. Macg"illivray, W. History of the Molluscous Animals of the 

 counties of Aberdeen, Kincardine, and Banff, 1843, P- 77- 



L. flaviis: I suspect that this may be a perpetuation of the error of 

 Gray (12). 



18. Morelet, A. Description des Mollusques terrestres et fluviatiles 

 du Portugal, 1845, p. 38. 



Limax sqnaniniatinus — stated by authors to be Geomalacus angtd- 

 formis — suspends itself by a thread. 



19. Saunders, W. W. Singular habits of Limax filans. Zoologist, 

 vol. 8, 1850, p. 2825. 



A slug can turn upon its suspensory thread and ascend it : 

 A short time since I noticed in a greenhouse ... a small slug . 

 gradually descending head foremost to some plants placed on a stand below . . . 

 I noticed my interesting acquaintance descend several inches in a few minutes; and 

 when it had completed a suspending-thread of fully eighteen inches in length, I 

 quite unintentionally put an end to its progress, by examining its outstretched eyes 

 too closely with a magnifying lens. After this affront the slug commenced a retreat, 

 which it got about by curving the head portion of the body upwards and inwards, 

 until it touched the hinder portion of the body, a part of which it actually climbed 

 up, and then took to the suspending-thread, advancing up the thread several 

 inches with great facility, although the thread at the time was oscillating con- 

 siderably with the draught of air through the greenhouse. 



'■^L. filans" here is probably Agr. agrestis. A statement in Tate's 

 "Land and Freshwater MoUusks of Great Britain," 1866, p. 79, is 

 evidently derived from Saunders; the facts are applied, however, to 

 L. arboruni. 



20. Binney, A. Terrestrial air-breathing Mollusks of the United 

 States, vol. i, 1851, p. 175; vol. 2, 185 1, p. 4-5, 22-42. 



In addition to the information already given (15), Binney notes 

 that young of Z. flavits (introduced from Europe), and those of 

 Philomycus caroliniensis suspend themselves by threads. He writes 

 further: 



. During the whole operation the locomotive disk is in active undulatory 

 motion, in the same manner as when in ordinary progression. . . . The slug 

 often pauses in its descent, and extends its tentacles and its whole body in various 

 directions, as if seeking some object on which to make a lodgment. The faculty 

 of suspending themselves in this manner inculcates that they pass some part of their 



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