As arranged by Lamarck, now comprises only such shells as are regular,
equivalve, and longitudinal; solid in substance, and attached to other
bodies by a short thick byssus.
In colour and appearance they greatly vary, some being smooth and
beautifully variegated with delicate colours, or radiated with purple
and white; some are coarsely ribbed or granulated, and have only one
colour, as black, blue, yellow, brown, or green; all are covered with an
epidermis, to which oftentimes the colour is confined.
Shell of a close texture, elongated, more or less oval, sometimes
sub-triangular, equivalve, summits anterior, more or less curved, a
little sloping inferiorly; hinge generally without teeth, or with two
very small rudimentary teeth; ligament dorsal, linear, sub-interior,
inserted in a long and narrow furrow; two muscular impressions, of which
the anterior is very small, with or without longitudinal grooves or
furrows.
Mytilus Magellanicus.
M. erosus.
M. crenatus.
M. decussatus.
M. hirsutus.
M. elongatus.
M. latus.
M. zonarius.
M. ungulatus.
M. violaceus.
M. opalus.
M. smaragdinus.
M. corneus.
M. edulis.
M. retusus.
M. Hesperianus.
M. perna.
M. exustus.
M. bilocularis.
M. ovalis.
M. ustulatus.
M. Domingensis.
M. Senegalensis.
M. Afer.
M. achatinus.
M. ungularis.
M. planulatus.
M. borealis.
M. Galloprovincialis.
M. angustanus.
M. lineatus.
M. lacunatus.
M. canalis.
M. incurvatus.
M. abbreviatus.
_M. incurvatus._ The incurvated Mytilus.
Nearly smooth, elongated oval, valves inflated and curved near the
ligament; apex acute.
_M. Afer._ The African Mytilus.
More or less compressed and sub-triangular, without grooves; byssus very
large and much developed; summit entirely terminal and anterior; smooth
and radiated with blue or purple, covered with a dark brown epidermis;
inside margin blue, shade decreasing to the centre.
_M. crenatus._ The crenated Mytilus.
Species longitudinally grooved, radiated, or striated.
_M. hirsutus._ The bearded Mytilus.
Species with grooves; covered with a shaggy or bearded epidermis.