Hannibal is the trade centre of a rich agricultural region, and has an important lumber trade, railway shops, and manufactories of lumber, shoes, stoves, flour, cigars, lime, Portland cement and pearl buttons (made from mussel shells); the value of the city's factory products increased from $2,698,720 in 1900 to $4,442,099 in 1905, or 64.6%.
The methods of oysterand mussel-culture are similar in principle to those just described.
The sea mussel (Mytilus edulis) belongs to the second order of the class Lamellibranchia, namely the Filibranchia, distinguished by the comparatively free condition of the gillfilaments, which, whilst adhering to one another to form gillplates, are yet not fused to one another by concrescence.
The byssus is a collection of horny threads by which the sea mussel (like many other Lamellibranch or bivalve molluscs) fixes itself to stones, rocks or submerged wood, but is not a permanent means of attachment, since it can be discarded by the animal, which, after a certain amount of locomotion, again fixes itself by new secretion of byssus from the foot.
Musculus, diminutive of mus, mouse, applied to small sea fish and mussels), a term applied in England to two families of Lamellibranch Molluscs - the marine Mytilacea, of which the edible mussel, Mytilus edulis, is the representative; and the fresh-water Unionidae, of which the river mussel, Unio pictorum, and the swan mussel, Anodonta cygnea, are the common British examples.
At the mouth of the river Conway in North Wales the sea mussel is crushed in large quantities in order to extract pearls of an inferior quality which are occasionally found in these as in other Lamellibranch molluscs (Gwyn Jeffreys).
Anodonta cygnea, the Pond Mussel or Swan Mussel, appears to be entirely without economic importance.
The mollusc reciprocates by throwing off its embryos on the parent fish, in the skin of which they remain encysted for some time, the period of reproduction of the fish and mussel coinciding.
Mussel fisheries, an industry confined to the Mississippi river counties from Lincoln to Lewis, are economically important, as the shells are used in the manufacture of pearl buttons.
- Diagrams of the external form and anatomy of Anodonta cygnea, the Pond-Mussel; in figures I, 3, 4, 5, 6 the animal is seen from the left side, the centro-dorsal region uppermost.
This was manufactured from the Mytilus californianus, a mussel which abounds there.
It is not obvious why these fresh-water forms have been associated popularly with the Mytilacea under the name mussel, unless it be on account of the frequently very dark colour of their shells.
Unio margaritiferus, the pearl mussel, was at one time of considerable importance as a source of pearls, and the pearl mussel fishery is to this day carried on under peculiar state regulations in Sweden and Saxony, and other parts of the continent.
The pearl mussel was formerly used as bait in the Aberdeen cod fishery.
The kima, a great mussel weighing (without shell) 20 to 30 Ib, and other shellfish, are eaten, as are also dogs, flying foxes, lizards, beetles and all kinds of insects.
The mussel (i-no.kai) is well represented by the species numa-gai (marsh-mussel), karasu-gai (raven-mussel), kamisori-gai (razor-mussel), shijimi-no-kai (Corbicula), of which there are nine species, &c. Unlike the land-molluscs, the great majority of Japanese sea-molluscs are akin to those of the Indian Ocean and the Malay archipelago.
Of the sea-mussel, again, and other shell-fish, he argued (in reply to a then recent defence of Aristotle's doctrine by F.
Buonanni, a learned Jesuit of Rome) that they are not generated out of the mud or sand found on the seashore or the beds of rivers at low water, but from spawn, by the regular course of generation; and he maintained the same to be true of the fresh-water mussel (Unio), whose ova he examined so carefully that he saw in them the rotation of the embryo, a phenomenon supposed to have been first discovered long afterwards.
- Human Clay Figure, with bead chain of mussel shells and of Venetian glass in the ears and on the neck; 1st period of Spanish conquest.
Stone axes, remains of carved stone pillars similar to those of Easter Island, and skeletons with a pearl-mussel beneath the head have been found in the island, though it was uninhabited when discovered by Philip Carteret in 1767.
As an example of the organization of a Lamellibranch, we shall review the structure of the common pond-mussel or swan mussel (Anodonta cygnea), comparing it with other Lamellibranchia.
II, A a portion of four filaments of a ctenidium of the sea-mussel (Mytilus) is represented, having precisely the same structure as those of Arca.
In length, which size is attained in three years after the spat or young mussel has fixed itself.
Unio pictorum, the common river mussel (Thames), appears to owe its name to the fact that the shells were used at one time for holding water-colour paints as now shells of this species and of the sea mussel are used for holding gold and silver paint sold by artists' colourmen, but it has no other economic value.
In Scotland and Ireland the pearl mussel fishery was also of importance, but has altogether dwindled into insignificance since the opening up of commercial intercourse with the East and with the islands of the Pacific Ocean, whence finer and more abundant pearls than those of Unio margaritiferus are derived.
Specific acts have also been passed for the establishment and development of oyster, pollan and mussel fisheries.
Other scale insects of note are the cosmopolitan mussel scale (Mytilaspis pomorum) and the Australian Icerya purchasi.