262 MYTILIDE. 
The common edible mussel frequents mud-banks which are 
uncovered at low-water; the fry abound in water a few fathoms 
deep; they are full-grown ina single year. From some unknown 
cause they are at times extremely deleterious. The consumption 
of mussels in Edinburgh and Leith is estimated at 400 bushels 
(= 400,000 mussels) annually; enormous quantities are also 
used for bait, especially in the deep-sea fishery, for which pur- 
pose thirty or forty millions are collected yearly in the Frith of 
Forth alone.—Dr. Knapp. Mussels produce small and inferior 
pearls. At Fort Stanley. Falkland Islands, Mr. Macgillivray 
noticed beds of mussels which were chiefly dead, being frozen at 
low-water. 
The species of Mytilus are usually found attached by a byssus 
in masses to stones, wrecks or floating bodies. The ligulate 
grooved foot has the power of spinning the silky material of the 
byssus whenever the animal requires temporarily to anchor itself. 
Boughs of elm and other trees are laid down in the Bay of 
Kiel, and taken up at the end of three, four, or five years, between 
December and March, being then covered with fine mussels, 
These laden boughs are sold by weight, and the shell harvest is 
sent into the interior of Germany, where it is in great request. 
AULACOMYA, Mirch. (Hormomya, Mirch. Arcomytilus, A gass.) 
Surface ornamented with radiating ribs. I. decussatus, Lam. 
(cxxviil,.92). 
cALOROMYA, Morch. MM. afer, Gmel. (exxviii, 93). 
MYTILOCONCHA, Conr., 1862. Subfaleate, thick, perlaceous, 
laminated; hinge thick, elongated; pointed at the apex; an 
oblique tooth or ridge and parallel furrow throughout the entire 
length of hinge-area. M. incurva, Conr. (exxik 11). 
BYSSOPTERTA, Hall, 1883. Shell erect, alate posteriorly, trun- 
cate with a nasute projection in front; surface radiated. MM. 
radiata, Hall. Fossil; Chemung Group, N. Y. 
MYTILoPs, Hall, 1883. Shell resembling Modiola and Litho- 
domus in external form, and may also be compared with the 
fossil genus Myoconcha; hinge-line narrow, oblique, extending 
about one-half the length of the shell; beaks terminal. 4 sp. 
Chemung Group, New York. J. precedens, Hall. 
STAVELIA, Gray, 1857. Shell inequivalve, inferior margin sinu- 
ous. J. torta, Dunker. 
Moprona, Lam., 1799. 
Etym.— Modiolus, a small measure, or drinking-vessel. Horse- 
mussel. 
Syn.—Perna, Adanson, H. and A. Adams. Amyedalum, 
Muhlf. Callitriche, Poli. 
Distr.—i0 sp. Universal. Chiefly tropical. MM. modiolus. 
Arctic seas—Britain. Fossil, 150 sp. Silurian? Lias—; United 
