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OBSERVATIONS ON THE PAIRING OF LIMAX MAXIMUS L. 



By LIONEL E. ADAMS, B.A. 



(With Plate III). 

 (Read before the Society, December 8, 1897). 



During the months of last July and August I devoted considerable 

 time to the observation of the pairing of this species, and as few 

 conchologists seem to be aware of the extraordinary manner in which 

 this takes place, the following account may be of interest. 



I may mention that my figures (kindly drawn by my friend, Mr. 

 J. W. Taylor) are all from carefully-measured sketches on the spot, 

 and that, though I have made drawings of a dozen or more ex- 

 amples, in no case did the measurements vary materially. 



The size of the organs is remarkable, but is accounted for by the 

 fact of their being congested with the sexual secretions. Dissection 

 of these slugs during the pairing season shows that the albumen gland 

 and the common duct occupy the greatest part of the interior. 



' How these slugs find each other I cannot say. It is certainly not 

 by sight, as (so far as my experience goes) pairing is only carried on 

 at night, between 10 p.m. and 2-30 a.m., though perhaps later. Nor 

 do they follow each other by their mucous tracks ; yet I have 

 seen an individual make straight for another on the side of a brick 

 wall from the distance of six or seven feet. Most likely the power of 

 scent mentioned in a note of mine in this journal (vide antea, p. 24), 

 is the explanation. This nocturnal habit is most fortunate for the 

 preservation of the species, as otherwise their enemies would find 

 them in an exposed and helpless condition. 



When the pursuer overtakes the pursued, each touches with its 

 tentacles the tentacles of the other, after the manner of ants. Then 

 begins a circular procession, 1 each with its mouth at the other's tail, 

 and this procession lasts from half an hour to two hours and a half. 

 Careful observation leads me to suppose that during this performance 

 each is eating the external mucus from the other, for a purpose 

 which will presently appear. The circle now grows more contracted, 

 the slugs overlapping and showing evident excitement, the mantles 

 flapping before and behind. Then, suddenly, the slugs intertwine 

 fiercely, and launch themselves into space, heads downwards, but 

 suspended by a thick strand of mucus, for the distance of 15 — -18 

 inches. This mucus thread, which they seem to have been col- 

 lecting for the purpose, is of a yellowish brown colour, and does 

 not seem to mingle with the mucus on their bodies. The fall is 

 generally as rapid as if there were no support, but is gently checked 



1 The habit of a preliminary circular procession is not confined to this species, as I have 

 noticed that Arion ater, Agriolimax agrcstis, and Ag. leevis affect the same peculiarity. 



