The smaller figures exhibit its larva condition (not specially described in the text).

Fig. 4. CARCINUS MÆNAS. a, b. Successive forms of its

metamorphosis

346

Fig. 5. BALANUS. a. Male. b. Larva ..

393

Fig. 6. LEPAS. a, b. Stages of its metamorphosis

395

"Bird's-heads" in different states of expan

sion.

437

PAGURUS BERNHARDUS.

359

CHAPTER XXXIX.

PAGURUS BERNHARDUS—“ HERMIT CRAB."

"But in the porch doth evermore abide

An hideous giant, awful to behold,

That stops the entrance with his spacious stride,
And with the terror of his countenance bold
Full many doth affray."

It is curious to observe the strange alliances by which animals of most opposite habits, and evidently remote from each other in zoological resemblance, are sometimes associated, the necessities of the one being provided for in an extraordinary manner by some peculiarity in the structure or general œconomy of the other, without which the existence of a creature so constituted would be impossible.

The PAGURUS BERNHARDUS, or HERMIT CRAB (Pl. VII. fig. 1), is a crustacean whose appearance must be familiar to every one frequenting the sea-shore. If it is not, the reader has only to take advantage of a low tide upon some shelving beach in order to gratify his curiosity. In such situations he will doubtless be puzzled at beholding a number of turbinated shells traversing the sands in all directions, as if of their own accord, but after a fashion evidently widely different from what would be followed by the proper

owners of the tenements. Some of these shells are of small dimensions, others much larger, all seeming to be wandering about after their individual pursuits, though not apparently guided by any common impulse. If the progress of these peripatetic shells be interrupted, they at once stand still, and then each of them is found upon examination to be the residence of a Hermit Crab.

To comprehend the shape of this animal, it is necessary to deprive it of its habitation. It is then seen to be formed of two distinct portions,-the head and a good portion of the body being covered with shell, like the fore part of a lobster; whilst the hinder, or tail portion, is bare, soft, and devoid of any solid protection; so that, in order to defend its nether regions, the creature is obliged to have recourse to the strange expedient of making an extempore sentry-box of any shells that, from their size and shape, may be adapted to such a purpose, and which the occupants are compelled to drag about with them on all occasions.

It is still a question undecided whether the Hermit Crab always selects for its habitation a shell already empty, or whether it does not sometimes actually kill and devour the original inhabitant before taking possession of its outraged abode, and thus add murder to piracy.

The fishermen on the coast state its proceedings for securing the ejection of the lawful tenant to be summary enough: the aggressor seizes his victimthe whelk for instance-immediately behind the head, and, after thus killing or disabling it, at once proceeds to eat it out of house and home, and then to