LYONSIA.
29
family.
Tliis relationsliip has also been remarked by
Carpenter in liis account of the microscopical structure
of the shell. The mantle-tubes are united in the present
genus, as well as in Fandora ; they are separate in the
Anatinida.
Philippi considered Lyonsia to be closely
allied to Galeomma ; but I cannot see much resemblance
between them. Mr. W. Wood was the first to notice
the curious appendage which covers the hinge. It was
conjectured by Clark that it acted like the check-tape of
a trunk, to prevent its being opened too widely. This
might be so if it Avere attached to the shell. I should be
disposed to attribute to it quite a contrary action, and
to believe that its use may be to strengthen the hinge,
and to protect it from being squeezed too closely and
broken, as is frequently the case with certain species of
Anatina and Thracia. The ossicle of Lyonsia is of a
different shape and position from that of the Anatinidce.
In those it is semiannular, and clasps the hinge crosswise
wdth the two ends ; in the present genus it is flat, and
lies over the hinge leiigthivise, wdth one end at the anterior and the other at the posterior side of it.
This genus has several synonyms, including Magdala,
Leach, Osteodesma, Deshayes, and Pandorinaj Scacchi.
Lyonsia Norve'gica"^, Chemnitz.
Mya Norveqica, Chemn. Conch. Cab. x. p. 345, 1. 170. f. 1647, 8. L. Norvegica, F. & H. i. p. 214, pi. viii. f. 6-9, and (animal) pL H. f. 3.
Body milk-white, sometimes with a tinge of yellow or pale
brown : mantJe thin ; edge studded at the anterior side with
from 8 to 10 papillae, which are of a darker hue in coloured
individuals : tubes nearly sessile ; orifice of the lower tube
fringed with a few short, thick, and close-set cirri ; upper
tube having a plain bulbous orifice, but furnished with the
* Norwegian.
29
family.
Tliis relationsliip has also been remarked by
Carpenter in liis account of the microscopical structure
of the shell. The mantle-tubes are united in the present
genus, as well as in Fandora ; they are separate in the
Anatinida.
Philippi considered Lyonsia to be closely
allied to Galeomma ; but I cannot see much resemblance
between them. Mr. W. Wood was the first to notice
the curious appendage which covers the hinge. It was
conjectured by Clark that it acted like the check-tape of
a trunk, to prevent its being opened too widely. This
might be so if it Avere attached to the shell. I should be
disposed to attribute to it quite a contrary action, and
to believe that its use may be to strengthen the hinge,
and to protect it from being squeezed too closely and
broken, as is frequently the case with certain species of
Anatina and Thracia. The ossicle of Lyonsia is of a
different shape and position from that of the Anatinidce.
In those it is semiannular, and clasps the hinge crosswise
wdth the two ends ; in the present genus it is flat, and
lies over the hinge leiigthivise, wdth one end at the anterior and the other at the posterior side of it.
This genus has several synonyms, including Magdala,
Leach, Osteodesma, Deshayes, and Pandorinaj Scacchi.
Lyonsia Norve'gica"^, Chemnitz.
Mya Norveqica, Chemn. Conch. Cab. x. p. 345, 1. 170. f. 1647, 8. L. Norvegica, F. & H. i. p. 214, pi. viii. f. 6-9, and (animal) pL H. f. 3.
Body milk-white, sometimes with a tinge of yellow or pale
brown : mantJe thin ; edge studded at the anterior side with
from 8 to 10 papillae, which are of a darker hue in coloured
individuals : tubes nearly sessile ; orifice of the lower tube
fringed with a few short, thick, and close-set cirri ; upper
tube having a plain bulbous orifice, but furnished with the
* Norwegian.