38 CHELTENHAM COLLEGE NATURAL HISTORY SOCIETY. 
Leaving Entomology we have next to notice the Hermit Crab 
(Pagurus Prideauxii) snugly lying in the shell of a whelk, or smaller 
individuals in the shells of the purpura. 
Patella pellucida lives on seaweed, the brown shell with its blue 
dots being in harmony with the brown leaves of Laminaria, besides 
being only uncovered at very low tides. 
The Pholas constructs its dwelling in a neat circular hole in solid 
rock. How it does this is still an open question: it has been sup- 
posed to do it either by using an acid which softens the rock, or by 
turning round its rough shell and so wearing away the rock. 
Chitons and Limpets are sometimes found covered with Algz. 
The Limpets, where there is no seaweed as Fucus Serratus or 
Fucus Vesiculosus to cover them, are worn at the top. Those sur- 
rounded by the weeds are not so much worn, but are lighter in colour, 
thus showing that the weeds protect the shells from the action of the 
water. 
The larger Limpets wear for themselves holes in the rock. (At 
Scarborough it is mostly soft sandstone, which can easily be cut with 
a penknife.) These holes are visible in very soft rock, and in some of 
them the shells are almost buried. The smaller fish will sometimes 
take possession of the vacated holes, which are often too big for their 
new occupants. 
A fairly common Sea Anemone (Tealia Crassicornis) covers itself 
all over with grains of sand and fragments of shells, so that not a bit 
of its green and red warted surface is to be seen, owing to its adopted 
coat which conceals its owner so well that it is rarely noticed unless 
expanded. 
Limax Agrestis setties on the underside of light coloured pieces of 
dead grass. 
But now we cone to the third method of protection,—Defence. 
In this the Puss Caterpillar, mentioned above, is one of the most in- 
teresting, as it possesses several means of defence. First there is the 
terrifying appearance, which is to prevent the caterpillar being 
touched ; the head is withdrawn into the next segment, while the red 
margin is prominently shewn. There are two black spots, one on 
each side of tbe body, which appear like eyes. If touched on one side 
it immediately turns its face towards the spot where it was touched. 
From the forks of the tail two pink cords can be pushed out and 
waved about like whips. Beyond this the caterpillar also secretes a 
powerful acid, which it can eject with considerable force. Hairy 
caterpillars are not so often devoured by birds as those without hairs, 
