ARION HORTENSIS. 213 



Reproduction and Development — The details of the congress of 

 this species have never been recorded, but Mr. E. J. Lowe, who has fre- 

 quently observed the act, describes it as very transitory, the actual congress, 

 during which the spermatophores are exchanged, only occupying forty or 

 forty-five seconds. 



The eggs, which have been so frecj^uently though erroneously described as 

 phosphorescent for the first fifteen days after deposition, are subglobular in 

 shape and a little over two mill, in length, semiopaque or quite translucent 

 and of a milky-white colour, which, however, soon changes to a dull yellow. 



They are deposited throughout the milder parts of the year, on the damp 

 earth, or beneath stones or other shelter, to the number of seventy or more, 

 agglutinated in several clusters by a yellowish mucus, and are said to hatch 

 in from twenty to forty days, according to the weather, the young even in 

 tlie earliest stages being said to show the same body markings as the 

 adults, and to possess a di.stinct keel, which is, however, readily overlooked, 

 as it is not distinguished by colour, and entirely disappears during growth, 

 the animal becoming full-grown and adult towards the end of the first year. 



Food and Habits. — Arion hortei/sis is essentially a garden species, 

 and especially partial to heavy soils, though often found far from culti- 

 vated land, in fields, woods, and in damp places beneath logs and stones ; 

 it is a rather active, but strictly geophilous species, seldom ascending any 

 distance up the stems of trees or plants, though both young and adults can 

 readily spin mucus threads to facilitate descent from elevated positions. 

 It is a most destructive animal, hiding during the day beneath violets, 

 strawberries, and other tufted plants, but coming out at dusk to feed, 

 continuing its depredations throughout the night, and as it feeds quite 

 at the base of the plants, its ravages are only discovered when too 

 late ; it will burrow down to the bulbs of lilies, and feed upon them the 

 winter through, it also eats off the bark from chrysanthemum stems, 

 devours pansy branches, and the stems of earthed-up celery. In spring 

 it will leave other food to feast upon the fallen petals of the apple aud 

 plum blossoms, and is if possible more destructive to strawberries than 

 even Agriolimtix agrestis. 



According to Dr. Scharff, this species probably lives chiefly on decaying 

 vegetation, as he has found it most numerous in gardens amongst heaps of 

 old weeds. 



In the potato-growing district around Selby, Yorkshire, Arion hortennis 

 committed great ravages among the crops during the spring of 1904, by 

 feeding up(]U and honeycombing the "potato-sets," and thus causing 

 a very serious blight. 



Mr. Gain found it a rather sicklj' species in cimfinement, and not so 

 indiscriminate in its choice of food as might have been supposed, as out of 

 193 different kinds of foods offered to a colony of the typical form, ninety- 

 one were totally rejected, and only twenty-five eaten freely, but not one 

 with that avidity which is so characteristic when a really favourite food is 

 offered. Dr. Scharff remarks that he has never found it on fungi, but in 

 confinement Mr. Gain observes that it fed readily upon Agnrlcus cam- 

 pestris, Eussula emetica, and several other species. 



Like AgrioUmax agre^th and Hilax sowerhii, this species is, according 

 to Mr. Reynell, strongly attracted by beer, and if this be placed in suit- 

 able shallow saucers in accessible positions on the ground, the animals 

 will crawl into the liquid and drown. 



