COLEOPTERA. - 501 
To change into a pupa, it shuts up the entrance to the shell with 
its old skin; and when arrived at the perfect state, quits the shell 
which served it as a temporary dwelling. The females of the 
Drilus flavescens take refuge under stones and dry leaves, or crawl 
slowly along the ground; whilst the males, which fly with great 
ease, are on the plants and brushwood. ‘These insects are not rare 
in the environs of Paris. M. H. Lucas has observed, in Algeria, 
near to Oran, another curious species, the Drilus mauritanicus. 
The larva of this insect lives at the expense of the animal of the 
Cyclostoma Volzianum, which closes the entrance to its shell with 
a covering of some calcareous substance. It fixes itself on the 
edge of the shell, with the aid of its sucker, and directs its strong 
mandibles to the side on which the snail is obliged to raise the 
covering, either to breathe the air or to walk. In this position 
it has the patience to wait for many days at the door. The 
snail puts off for as long a time as he is able the fatal moment. 
But when, overcome by hunger or nearly stifled in his prison, 
he decides at last to open the door, the Dridus profits immediately 
by this opportunity, and cuts the muscle which keeps back the 
foot of the snail. The breach being made, nothing more opposes 
itself to the entrance of the enemy. He slips in, and sets to work to 
eat at his leisure the unfortunate inoffensive mollusc, which affords 
him board and lodging. The Péilodactylides, the Hucinetides, and 
the Cebrionides belong to the same family. The first is exotic. 
The Hlateridé are rather large insects, often of hard texture, 
having the prosternum prolenged into a point (Figs, 549 and 550), 
and the antenne indented saw-wise. They have the power of 
jumping when placed on their backs, and of alighting again on 
their legs. Hence their name of Hater (derived from the same 
root as the word elastic). They produce, in leaping, one sharp 
rap, and often knock many raps when they are prevented from 
projecting themselves. This is the mechanism which permits the 
skip-jack to execute these movements. It bends itself upwards 
by resting on the ground by its head and the extremity of the 
abdomen, and then it unbends itself suddenly, like a spring. The 
point at the end of the thorax penetrates into a hollow of the 
next ring; the back then strikes with force against the plane on 
which it rests, and the animal is projected into the air. It repeats 
