Page:The common shells of the sea-shore (IA commonshellsofse00wood 0).pdf/17

Rh sixty or seventy feet, and sometimes grows to an enormous size, the individuals being as large as jargonelle pears. The outer tunic is peculiarly stout, and almost gristly in texture, and its colour is exceedingly variable, taking every intermediate shade from green to brown, sometimes being quite dark, and sometimes so pale that scarcely any colour is to be seen. In this genus, the aperture at which the water enters— and which is therefore called the inferent orifice—is surrounded with eight little lobes; while the other, or efferent orifice, is six-lobed.

Immediately above this object is drawn a curious species of the same group. Its name is Pelonæa corrugata, and it is remarkable as much for its habits as its shape.

It is not fixed to any object, but is as motionless as if it were attached to a rock, and seems to pass a singularly unenjoyable existence. Yet it is doubtlessly happy in its own way, though that way is a very strange one. It lives imbedded in the mud, its whole body being sunk, and only the ends of the two apertures projecting into the water. In consequence of this habit, the orifices are not placed at a distance from each other, as in the species which we have already examined, but are set closely together, and at the very extremity of the body. The name Pelonoæa is of Greek origin, and is very appropriate, inasmuch as it signifies a dweller in the mud.

There are several British species of Pelonæa, two of which, at least, inhabit the British shores. The present species is dark brown in colour, and has the lengthened body covered with wrinkles; whereas in the other species, Pelonæa glabra, the body is shorter in proportion, the colour is greenish yellow, and the surface is smooth and hairy. Zoologists set great value on this rather unsightly animal, as it forms a link of transition between the Tunicates and the more perfect Molluscs.