13*2 
ON THE STRUCTURE AND HABITS 
the rapidity of lightning; Nature having apparently given it this power of motion 
in order to make up for its otherwise contracted movements. The possession of 
power in the tail is not confined to the Lobster. Shrimps and Prawns are indebted 
for their activity to the construction of this part of their skeleton ; and the little 
Sand-hoppers, which are so common under the weeds at the sea-shore, make use 
of this organ to enable them to escape from any intruders. 
A little animal of this tribe, called the Sea-louse (Limnoria terebrans ) is but 
too well known for the attacks it makes on vessels, boats, bridges, or, in fact, any 
kind of wood remaining in still salt-water. It appears to feed upon the wood, 
and nothing can prevent its attacks. Where wood is in still salt-water, there 
will it be found. Some of the most valuable piers in this kingdom have sustained 
immense injury from this little animal. The wood of the new pier at Southamp¬ 
ton is quickly going to destruction from the attacks of this little intruder. 
Another curious family of these creatures is formed by the Hermit-crabs 
( Vagurus ). It is seldom that we find members of the animal kingdom availing 
themselves to any extent of the labour of others, without rendering something in 
return, even in members of the same tribe or family; but in the Hermit-crab we 
have a remarkable instance of an animal taking up its abode in the habitation 
of an animal quite different from itself. These Crabs have a very soft body, 
apparently little adapted to resist the rude knocks they must meet with in the 
restless element they dwell in ; they seem aware of this, and instinct directs them 
to take up their residence in the first unoccupied shell they meet with. It is 
most commonly that of the Whelk; but it is found inhabiting many others. 
Some of these animals are aquatic, others terrestrial. They abound in the Indian 
isles, and their shores are covered with them. “ When the heat is most intense,” 
says Mr. Kirby, “ they seek the shelter of the shingles, and when the freshness 
of the evening breathes, they run about by thousands, rolling along their shells in 
the most grotesque manner, jostling each other, stumbling, and producing a noise 
by the shock of their encounters, which announces their approach before they 
appear.” 
Another interesting member of this group of animals is the Land Crab. These 
animals are natives of the mountainous districts of the West Indies and South 
America. At certain seasons of the year they descend to the sea-side, to deposit 
their young. In doing this they go in such enormous numbers, that the woods 
and roads are covered with them. Like an army, they march in a regular line, 
without breaking their ranks, taking every thing in their way. Nothing stops 
them, scaling houses, over-running gardens, and surmounting every obstacle. 
Having arrived at the sea-side, they execute the purpose for which they come, 
and return again to the mountains, in the same orderly manner.* 
* See Naturalist, Yol. III., p. 49 .—Ed. 
