Pvn H,i I'UitlS

370 TELLINID.E.
Genus II. TELLI'NA *; Linne. PI. VII. f. 3.
Body oval, compressed : tubes slender ; orifices cirrous, or
plain.
Shell oval, triangular, or oblong, in some species slightly
inequivalve, more or less inequilateral, sculptured by concentric
laminae or stria?, arid occasionally by longitudinal (or
partially by oblique) striae ; posterior side flexuous : teeth, two
cardinals in each valve ;
laterals on either side or on one only
of each or one valve, but not always present : inside margin
smooth.
name is de-
According to Aldrovandus the generic
rived from the quick growth of the shell. He cites
Aristotle as his authority; but the expression of the
latter (ore ra^iara jlvovtcii reXelai) was used with re-
ference to every sort of shell-fish. Mr. William Wood's
work, f General Conchology/ published in 1815, con-
tains a monograph of all the species of Tellina which
were at that time known : it is well executed and prettily
illustrated. He explained, better than Montagu
had done a few years previously, the use of the siphonal
tubes, as well as of the linguiform organ usually termed
a " foot." As Lamarck observed, the two valves of the
same individual are not always perfectly alike -, some-
times one valve is more convex than the other. This
inequality of size occurs to a certain extent in our T.
crassa and T. squalida. The species are exceedingly
numerous, both in a recent and fossil state ; according
to Chenu there are 220 of the former, and nearly half
as many in secondary and tertiary strata. Searles Wood
says that " the genus appears as early as the Coral Rag,
with some doubtful forms in the Palaeozoic Formations."
Their shells are of an elegant shape, and often variegated
by bright-coloured rays and other markings.
* The name given by Dioscorides to a kind of shell-fish.