ARION SUBFITSCUS. 



197 



Mr. Gain found that of 130 different kinds of food tendered to them 

 while in confinement only one, the Violet ( Viola ddmxita) was eaten with 

 avidity, although forty-six other kinds were eaten freely, forty less readily, 

 and only forty-three were totally rejected. 



This species frequents both deciduous and pine forests, and ascends the 

 mountains to the limit of trees, but it also lives in gardens at the foot of 

 walls and rocks, under hedges bordering meadows or roads and other places. 

 It is fairly plentiful on the London clay, in gardens, etc. , in North London, 

 but is often especially abundant, fine and richly coloured on or near refuse- 

 heaps. Like its congeners, it is somewhat slow, timid, and clumsy, though 

 more active than A. ater, but when young or partly grown is a great adept 

 at spinning mucus threads, and has been known to spin a thread thirty- 

 seven inches in length. It is one of the few species of slug which has been 

 actually observed and recorded as able to reascend its thread. This is 

 effected by curving the anterior part of the body upwards until the fore- 

 part of the foot comes into contact with the hinder portion, up which the 

 creature then crawls until the thread is reached, the animal then applies 

 its foot to the thread, and at once proceeds to ascend by its aid, the 

 foot remaining nearly flat or only slightly folded in front. During the 

 operation the head is moved from side to side and mucus gradually accu- 

 mulates in an irregular mass above the tail, evidently composed in part of 

 the slack of the thread, as it could be to some extent unwound or disen- 

 tangled from the mass. 



Parasites and Enemies. — The general enemies of the slugs also 

 prey upon this species, but, according to Mr. L. E. Adams, poultry which 

 refuse Arion ater will eat this species without hesitation. Numerous 

 intestinal worms have been at times detected within this slug, but they 

 have never been identified. 



Variation. — This species does not display that wealth of colour- 

 variation shown by Arion ater, the variations being chiefly due to the 

 greater or lesser intensity of the rufous tint, and the more or less complete 

 overspreading of the body by the darker hue of the dorsal surface ; this 



Fig. 216. Fiu. 217. ViC. 21S. 



Proximal ends of the Reproductive Organs of Arion lusitanicus and A, nobrci. 

 Fig. IVa.— Arion lusitanicus (after Polloiiera). FiG. 111.— Arion lusitanicus (after Simroth). 



Fig. in.— Arion nobrei («.hi\ Polloneia). 



distribution of colouring is, however, hable to be reversed, a variety_ found 

 on the Serra d'Estrella having the dorsum clear brown, while the sides of 



