56 GAIN : FOOD AND HABITS OF SLUGS AND SNAILS. 



Of the Arions I find A. ater by far the most greedy feeder, 

 taking seventy-two per cent, of the foods given it ; it is also 

 occasionally guilty of cannibalism, the larger captives gnawing off 

 the skin of the smaller. A. hortensis is rather sickly in confinement and 

 very frequent additions are required to keep the colonies up to their 

 original numbers ; this species took sixty per cent, of the foods 

 offered. A. bourguignati ate exactly one-half of the foods given ; 

 this slug thrives and breeds freely in confinement. 



Some of the slugs can sustain long fasts without any apparent 

 inconvenience. Limax arborum has remained without eating for 

 five weeks, though food which it will take has been offered, and 

 L. flavus has fasted for nearly as long. One of the latter 

 deposited sixteen eggs beneath a stone placed in its cage ; these 

 are seven millimetres in length, oval, with a small point at each 

 end as if they had been connected by a filament which had been 

 broken- they are white, and when first seen were as transparent and 

 bright as a drop of water. The eggs were deposited on July 19th, 

 and about half hatched on the 15th of August; the young, of a 

 pale-yellow colour and almost transparent, attained a length of 

 n mm. when fully extended. 



Limax arborum has a curious habit of excavating a grave-like 

 trench its own length, with perpendicular sides about an inch in 

 depth, in which it lies ; either the original excavator or his companion 

 has occupied the trench on two occasions subsequent to its formation. 

 On examination I have failed to discover eggs either in the trench or 

 in the surrounding earth. 



Among the Helices experimented with, H. arbustoi urn is by far 

 the most voracious, taking sixty-one per cent, of the foods given, and 

 eating largely ; of those neglected only two were taken by any other 

 Helix among those experimented with. 



Helix nemoralis and H. hortensis agree in their choice of foods in 

 ninety-one cases out of a hundred. Taking this fact with the general 

 resemblance of the two species it has occurred to me that perhaps 

 we have here a case of comparatively recent development of two 

 species from an original ancestor, or of one from the other. After 

 three years' trial I have failed to get these two species to breed 

 together. Though I have succeeded in breeding both, they obstinately 

 refuse to cross. 



A fine example of Arion subfuscus, received from Mr. Roebuck on 

 the 27th August, deposited, Sept. 5th, about thirty eggs on the surface 

 of the earth, glued together in a mass, each egg 2J mm. in diameter, 

 milky-white and translucent ; these became yellowish in a week or 

 ten days. On the 23rd September this slug deposited a second cluster 



Naturalist, 



