236 REMARKS ON OONCIfOLOSY AND MALACHOLOGY. 
of ordinary foes. This mechanism doubtless assists the progress of 
the animal through sand in which it frequently borrows. 
The Cerithium lineolatum of a Gray” bas been already alluded to, 
there are two shells of this Genus, neither of which I have seen des¬ 
cribed though I observed one of them named as above in a collec¬ 
tion of the land and fresh water shells of Penang, made by Dr. 
Cantor, the shell so designated is about an inch and a half in length, 
thin and fragile, of a brown colour, with obscure transverse bands 
of a lighter hue, aperture more rounded than is usual in the Genus 
Cerithium, spire always truncated in the full grown shell, head and 
anterior part of the animal bright red like coral: the other species 
which I have more particularly observed in Singapore, has rather a 
larger shell, thinner and more fra gile than the other and of a darker 
colour, the animal is brown or nearly black and like the former, the 
spire of the full grown shell is always decollated; young specimens 
of the shell have perfect, sharp pointed spires, andthe convoluted ex¬ 
tremity of the animal then entirely fills the spiral part of the shell. 
but as the animal increases in size, its posterior extremity becomes 
more blunted and gradually retreats towards the anterior part of 
the shell, and as it successively abandons each turn of the spire, it 
throws out a viscid secretion which forms a hard shelly partition be¬ 
tween its new situation and the disused extremity of the spire, which 
being deprived of its usual nourishment, soon becomes worn into 
boles and finally drops off: thus the shell when arrived at maturity 
has always the appearannce of being imperfect. The habits of the 
animal are mixed and peculiar; sometimes it may be seen in a half 
torpid state, the operculum firmly closed suspended by a glistening 
thread, from the branch of a tree; when in motion it leaves behind it, 
a shining track like that of a snail; at the sides of an elongated pro¬ 
boscis are two tentacula, apparently short, blunt, and with eyes at 
their extremities: now as the Genus Cerithium is described as 
having the eyes at the base of the tentacula , this would appear 
a very remarkable deviation, and I was disposed to consider it as 
such until I had an opportunity of remarking the movements of the 
animal in water, where it is as often found as on land. When closely 
observed in that element, it is seen to expand two slender, pointed, 
tentacula of so delicate a structure that when out of the water 
they are lax, flaccid; and doubled under the protuberant eye, so 
