474 
FLEMING’S HERMIT-SCREW. 
the muddy parts of the sea-shore. This creature is common in the summer and early autumn, 
at which times it walks boldly upon the wet shore. During the later part of autumn and the 
winter, it resides in holes which it burrows into the mud and clay, and in some places is so 
plentiful, that the mud is quite honeycombed by its tunnels. This species is very common on 
the French coasts, especially in the great mussel preserves near Rochelle. M. D’Orbigny, who 
observed their habits closely, has given a very animated account of their manner of feeding. 
The whole of the muddy deposit along the shores is inhabited by myriads of marine 
worms, such as the nereis and lug- worm, and upon these the Corophium feeds. As the tide 
rises, the worms ascend to the mouths of their burrows, for the purpose of eating the little 
animalcules that swarm on the shore. The Corophium wages continual war against these 
worms, darts at them with surprising speed, fastens on them, and eats them. Sometimes a 
great lug-worm will be surrounded by thirty or forty of these curious Crustacea, all attacking 
it simultaneously, and forming a strange group as the worm writhes in its endeavors to 
escape, and carries with it the small but pertinacious foes under whose attack it is sinking. 
Hundreds of the Corophium may be seen beating the mud rapidly with their enormous 
antennae, for the purpose of discovering their prey, and the energy of the movement and the 
evident excitement under which the creatures labor partake largely of the ludicrous. They 
do not restrict themselves to the worms, being equally ready to prey upon fishes, oysters, or 
indeed any animal substance that comes in their way. The fishermen, who know it by the 
name of Pernys, are very angry with this little creature, and declare that it robs them of 
their mussel harvest. They even assert that it climbs the posts of the complicated wood-work 
to which the mussels cling, cuts the silken threads by which these mollusks are attached, and, 
having thus let them fall into the sea, eats them at leisure. As is the case with the sand- 
hopper, the Corophium is greatly persecuted by larger creatures, and is eaten in vast numbers 
by birds and many fishes. All the members of this genus can be recognized by the enormous 
dimensions of their antennae, which are extremely thick at the base, and look much more like 
a very large pair of legs than true antennae. 
We now come to some very curiously shaped Crustacea, whose habits are fully as remark- 
able as their forms. Their scientific name is Phronima, and their best known species is 
Fleming’ s Hermit-screw. This creature incloses itself in a nearly oval and transparent sac, 
which is found to be the body of one of the medusae. M. Risso tells us that, like the argonauts 
and carinariae, these creatures may be seen in calm weather voyaging along in their glassy boats, 
and rising to the surface or sinking through the water at will. They live on animaculae, and 
for the greater part of the year remain in the muddy depths of the ocean, ascending to the 
surface in the spring. How they enter their habitations, and their general economy, are 
subjects at present obscure. 
There are several species of Phronima, all inhabiting similar dwellings. Phronima 
sentinella , fo example, chooses the bodies of the gequorige and geronige for its home. These 
creatures are called by the name of Hermit-screws on account of the solitary lif e which they 
lead, each shut up in its cell or cocoon, as it may possibly be called. In all the Hermit- 
screws, the head is large and vertical, with two little antennae, and the body is soft, nearly 
transparent, and ends in a number of bristle-like appendages. All the legs are long, slender, 
and apparently weak, except the fifth pair, both of which legs possess a large and powerful 
claw, and are directed backward. 
A little crustacean belonging to an allied genus is not uncommon on European coasts. It 
has habits of a somewhat similar nature, dwelling in the chambers within several common 
medusae. It will occasionally leave this curious residence, and return to it at will. It is about 
half an inch in length, has the two first pairs of feet shortest, tipped with a claw, and has the 
three last pairs of legs longer than the others. The name of this crustacean is Metcecus 
medusarum. Mr. Spence Bates separates all these parasitic animals into a distinct family, 
under the name of Phronimadse. All the members of this family have the mandibles very 
large, some of the legs prehensile and oddly formed, and the head of enormous comparative 
size. Some of them attach themselves to fishes, and others to mednsge. 
