MALTA AND SICILY. 
165 
shells to our small collection. We often 
find in our net some curious animals of the 
genus holotkuria: they are of a dark brown 
colour, and in appearance are not unlike 
large kidney potatoes. They are certainly 
very low in the scale of existence, for the 
only proof they give of possessing animal 
life is a slow twisting motion ; and on dis¬ 
section, they are found to consist of an ex¬ 
ceedingly tough thick skin, the contents of 
which leather-bag are chiefly water and sand. 
But though their skin is so hard, they have 
the power of fitting themselves exactly into 
any inequality of the surface, and when laid 
in a basket, they soon become indented 
with an impression of the wicker-work, 
which appearance continues for some time 
after they are removed. Some of these sin¬ 
gular creatures are seven or eight inches in 
length, and nearly as thick as a man’s wrist. 
