THE CHINESE PEARL-MUSSEL. 427 



broken into a chamber already excavated by another individual, and forced its way 

 fairly through the inhabitant as well as the habitation. 



The animal is slightly luminous, as is the case with most of the burrowing molluscs. 

 The color of the shell is uniformly pale brown. 



The FINGER DATE-SHELL, which is seen lying on the ground just under the Mussel, is 

 a rock burrower, and so beautifully decorated that it seems a sad pity to bury so lovely a 

 shell in so dark a recess. At a little distance it is quite ordinary in appearance, being 

 apparently a plain, mahogany-colored shell ; but when examined closely, it is found to 

 be elegantly formed, colored with a peculiarly rich ruddy brown hue, and sculptured 

 with myriads of minute waved ridges and channels drawn crosswise over the shell, which 

 give wonderful effects of light and shade, and heighten the tints materially. The 

 animal is edible, and is eaten like that of the common Mussel. 



ON the upper part of the illustration, and towards the left hand, may be seen a 

 rather curious-looking shell, which, from its rude resemblance to the familiar toy of 

 childhood, is called the NOAH'S ARK. 



The Ark-shells are found all over the world, hidden under stones, in the crevices of 

 rocks, or even within the forsaken burrows of the pholas or the date-shell. Owing to 

 their retiring habits, and the nature of the localities in which they live, they are mostly 

 distorted or damaged. They can move themselves very fairly by means of a curious 

 conical byssus, composed of a series of thin plates, which can be cast off or re-formed 

 at the will of the animal. 



IN the two species represented in the following illustration, we have examples of 

 pearl-bearing molluscs inhabiting the fresh waters. 



THE BRITISH PEARL-MUSSEL was once a valuable inhabitant of our rivers, on account 

 of its contents. It is now, however, seldom sought except for bait, and in the latter 

 capacity is more useful than in the former, as it is estimated that not more than one 

 per cent, contain any pearls, and not more than one per cent, of the pearls is of any 

 commercial value. The older and more irregular the shell, the better chance is there of 

 finding a pearl ; and a diligent collector may soon obtain a tolerable series of these 

 objects for his cabinet. Now and then, however, a really fine pearl is found ; and one, 

 that was obtained from the Conway, now holds a place in the crown of England. 



This Mussel is tolerably active, and, if laid on the sandy or muddy floor of an aqua- 

 rium, will soon assume its usual attitude. It begins by gently opening the shell and 

 pushing out its foot, and, after a serie , of apparently aimless movements, succeeds in 

 setting itself on its edge. It then forces itself forward, leaving a deep groove behind it, 

 or wriggles itself downwards until only an inch or so of its shell protrudes. The edges 

 of the shell are sharp as knives ; and many a timid bather, who is afraid to swim, and 

 contents himself with paddling about in shallow water, has suffered severe cuts on the 

 foot from these treacherous inhabitants of the water. 



The interior of this Mussel is of a lovely azure, and the exterior exhibits beautiful 

 colorings when cleaned with a very weak solution of muriatic acid and then polished. 

 It is a very prolific species, the outer gills of the female containing a vast number of 

 tiny Mussels not yet able to obtain their own living, and waiting until they have gained 

 sufficient strength to be launched on the world. One specimen will produce nearly 

 three hundred thousand young in the course of a year. 



THE genus to which the CHINESE PEARL-MUSSEL belongs is distinguished by the thin 

 elastic wings into which the valves are produced. 



From this species the Chinese, those incorrigible tricksters, "are in the habit of 

 producing imitation-pearls by a very simple process. A string of small shot is introduced 

 between the valves, and the animal restored to its native element. The irritation caused 



