LIMA HIANS AND ITS MODE OF LIFE. 223 
once remove to another and safer part of its tunnel. But the use 
of the longer and more glandular tentacles is more puzzling. 
There is little doubt that it is by their means that the feltwork of 
the nest is smeared with the slimy secretion which occurs through 
it. When closely examined, this sticky coating is found to have 
caught up great numbers of diatoms, doubtless brought in by the 
constant current of water. The object of this smearing, if it has 
an object, is rendered more obscure by the observed fact (M‘Crie) 
that the excreta of the animal are also caught in this way. 
Several observers have mentioned the offensive and persistent 
odour imparted to the hands after handling the animals, no doubt 
from this mucus, and it might be suggested that this is a means 
of warding off enemies. This, however, cannot be accepted till 
at least we know more of the so-called “olfactory” organ of 
marine animals. It is a well-known fact that our olfactory organs 
are quite incapable of appreciating any smell in a liquid applied 
to the sensory epithelium. A recent writer has gone the length 
of denying any power of “smell” to any purely marine animals. 
So far then as we can judge from histological evidence, the 
function of these longer tentacles is the smearing of the nest with 
mucus, to ascertain the object of which requires renewed 
observation. 
These longer tentacles may be irritated or even cut off without 
disturbing the animal, and we have seen that it probably has the 
power of throwing them off when they become fixed in any way 
—a most valuable accomplishment—as the animal can thereby 
readily escape when these tentacles, which wander so far from the 
nest, are seized by some of its enemies with hostile intentions. 
Many other molluscs (Nudibranchs) exhibit the same power. 
Besides the secretory and sensory elements, there are also well- 
developed muscular elements, and these play a part in the 
functional activity of the tentacles. Mr. M‘Crie has observed 
the animal wholly suspended in the nest by their means, and 
perhaps, along with the.foot, they play a part in the arranging of 
the material of which the nest is built, for if it be examined 
closely, some kind of assorting is evident in the disposition of the 
twisted and branched nullipores. 
There is in Lima another modification of the mantle which 
serves almost as unique, though more apparent, a purpose. We 
‘have described the mantle as giving rise to a number of processes 
