618 ABOUT SHELLS. 
some degree of moisture prevails; for example, in the 
ground or among the dead leaves covering it; in a hollow 
tree or in the crevices of the bark; under stones or among 
the leaves of epiphitic Tillandsias. But occasionally an 
individual is found abroad at this season, and repeated ex- 
amination led me to discover a reason for it; whether it is 
the reason, may remain for wiser ones to determine. These 
shells are commonly stuck fast where they are found, or 
glued as it were, and not merely adhering’ as in a time of 
rest in the wet season. And they have all been injured,— 
the shell more or less broken. Are they going to die? Are 
they undergoing repairs? This last seemed to me more prob- 
able. They are always, in part at least, grown together, not 
quite symmetrically often, but generally quite firmly. Do 
they eat by night as in the rainy season? This I cannot 
assert. The firmness of. their attachment would indicate 
that they do not. So uniform has been my experience in 
this case, that now, if I see an Achatina, or a large Helicina, 
on a tree in the dry season, however inviting they may ap- 
pear at a distance, I pass them by as worthless. ; 
Oleacina and its allies are carnivorous snails. They have 
a smooth polished delicate shell, yet possess the power to 
capture and devour others many times larger than them- 
selves, besides being protected by a firm shell, and with a 
closely fitting hard operculum. Not unfrequently we find 
large shells like Helicina regina, or H.sagreana, quietly sub- 
mitting to be devoured by an Oleacina, which it has the 
strength to walk off with, as easily as a tortoise could carry 
away a mouse. Wherein lies their great strength? [cam 
offer a suggestion. I have often been in such situations = 
the face of a vertical cliff, that I needed both hands for sup- 
port. At such times, if a shell attracted my attention, I 
used to put it between my lips till I reached a place where 
both hands were free. Thus I learned, that the watery T 
‘slimy secretion which all these animals emit, in the case A 
this group, is bitter; and in the larger species, very deck 

