Nanina. 459 
swelling so much that if it is suddenly thrown into boiling water, the 
attempt to return into the shell invariably causes a fracture of the aper- 
ture. Drought, however, effects its retraction gradually, and it then 
covers itself with a whitish false operculum, similar to those of other 
Helices. The shell itself differs in nothing but superior size from the 
common little Helix lucida of Europe. ‘The animal is dark brownish 
with the exception of the sole and the posterior extremity, which are 
livid. The colour of the animal seen through the polished diaphanous 
rown shell'has a very rich appearance, 
Besides the narrow edge of the mantle which is reflected over the 
sharp edge of the aperture forming a fold on the outer surface, two 
processes are projected over the shell; one of them is thrown off at the 
upper angle of the aperture, near the foramen commune, the other at 
the periphery; both are extensible, corrugated, and flexible in every 
direction, the upper one reaching, when extended, beyond the apex of 
the sheli. They are continually in motion and exude a liquor which 
lubricates the shell; supplying, apparently, that fine gloss which is 
observable in all recentspecimens. There is an orifice under the posterior 
caudiform appendage in the form of an isosceles triangle with the apex 
downwards, whence a thick greenish juice exudes when the animal is 
handled or irritated, the caudal appendage being turned up and protruded 
towards the exciting object. This appendage much resembles the anal 
horn of the Sphyna caterpillars, One of the largest specimens which 
I have seen was much injured by being repeatedly dropped by a gentleman 
who discovered it crawling on a rock, and who was deterred by the 
threatening appearance of the tail, which he imagined might contain a 
sting, and with which it endeavoured to reach his finger when seized. 
The motions of the animal are quick as compared with those of its 
congeners, and like Helicolimaz it only crawls the faster when disturbed, 
instead of retracting its tentacula. It carries the shell horizontally or 
nearly so, while in Helix the axis of the shells forms a very large angle 
with the horizon, 
It deposited much excrement in long curled rolls which were brown 
when the animal was newly captured, but when fed on the leaves of an 
