230 ARION CIRCUMSCRIPTUS. 
Reproduction and Development.—The congress of this species has 
been observed by Mr. E. J. Lowe, who remarks that the act is, as in Arion 
hortensis, very transient, scarcely oceupying more than forty to forty-five 
seconds, but the spermatophore has not as yet been noticed or described. 
The eggs are deposited in moist sheltered positions, in clusters of twelve 
to fifteen, adherent by a sticky mucus, and have been observed from 
June up to November; they are oval, but somewhat variable both in shape 
and size, usually of a semitransparent white when first deposited, but 
gradually becoming opalescent or pearly. The young are said to be usu- 
ally of a delicate grey, and to show the lateral banding from birth, as well 
as a distinct dorsal keel, the latter, however, is usually gradually lost 
during growth, its position being represented by a line of whitish mid- 
dorsal tubercles at maturity, a state which would seem to be attained 
about June and July. 
Food and Habits.—This species is much less slimy than Arion 
hortenis, and unlike that species, is essentially a frequenter of grass fields 
or uncultivated ground, and not common in gardens. Like its ally, it 
however is a truly geophilous and nocturnal species, and in feeding only 
ascends a short distance up a plant, though capable of spinning mucous 
threads both in its young and adult state. 
According to Baudon, it is rather common on decaying tree-trunks, 
under fallen leaves, and in the stem and cap of large mushrooms of which 
and other fungi A. circumscriptus is particularly fond. 
It isa very sluggish and slow species, bunching wp and spreading out its 
margins when at rest, and remaining inert as though torpid. It fixes itself to 
wood or stone, and according to Mr. Sherriff ye, when humped-up in such 
places, looks like a grey pebble, and does not seek to escape from the place 
where it is fixed. According to Baudon, it often excavates little galleries in 
the earth under old trunks, in which many individuals may congregate, and 
which serve for retreats when the temperature is too hot or too cold. 
Mabille describes it as a winter species in France, but in this country 
the winters are more severe and it is rarely met with at that season. 
In captivity, Dr. Scharff found them to eat pieces of apple or rhubarb 
stalk, while in the garden they seemed to prefer to feed on the fallen and 
partially-decayed flowers of the pea, instead of attacking the living parts 
of the plant, like A. agrest’s. Mr. Gain found this species to thrive and 
breed freely in confinement, but of 193 different kinds of food offered, only 
thirty-three were taken freely, while ninety were totally rejected. 
Variation.—This species, being one of our more primitive and ancient 
forms, does not display that wealth of variation shown by the more 
recently evolved species, and although many varieties and even species 
have been set up, based chiefly upon the differing shades of dermal colour- 
ing, yet these are all clearly referable to two chief lines of variation ; one, 
which is chiefly found on cultivated land and gardens, is distinguished by 
the yellowish or brownish shade of its colouring, due to the development 
during growth of a number of reddish tegumentary pigment cells ; the 
other partakes of the grey tint of the typical form, but is liable to darken 
with age, and also displays more distinctly a certain concentration of the 
yellow pigment in the form of a supra-pedal longitudinal zone, and is a 
form more especially characteristic of the open country. 
‘he shght dorsal keel, invariably present in the immature individuals, 
but which is usually gradually obliterated during growth, may, however, 
