ACICULA. 
39 
abundance of very clear aqueous mucus. It often 
leaves half the foot exposed when all the other 
parts are withdrawn. 
1. Acicula. 
Shell subcylindrical, with a blunt tip; mouth ovate^ 
simple^ outer lip simple^ thin^ slightly reflexed 
over the pillar^ forming a slight perforation. Ani- 
mal with two long contractile slender Fig, lo. 
tentacles^ between which and the 
eyes^ at their hinder base, are two 
jagged blackish spots (fig. 10.). 
Dr. Turton (^Manual, ed. 1. p. 83.) appears to 
have considered the spot at the base of the tentacles 
as the rudiment of a lower pair. Dr. Hartmann 
(^Sturm^ Fauna^ t. 1. f. 4.) describes the tentacles as 
retractile; but he uses the same term to describe 
the tentacles of Cyclostoma and Carycliium^ which 
agree with these in only being contractile, and not 
retractile like those of Helices^ and other land Mol- 
lusca. 
This genus, on account of the similarity of its 
shell, has been confounded also with Truncatella of 
Risso, which is a marine animal, provided with gills 
and a distinct operculum. 
The animal walks with its shell nearly perpen- 
dicular, twisting it round in a very odd manner, and 
then letting it suddenly fall again. 
9. 1. Acicula Brown Acme. — Shell cylin- 
drical, obtuse, glossy brown, transparent, with 
