2
SOLEXID.E.
form elongated prisms, ^\'ith walls as straight and parallel
as those of Pinna ; but their axes are nearly conformable
with the surface, cropping out somewhat obliquely upon
the exterior, w^here their rounded terminations with
distinct nuclear spots may sometimes be seen. The
internal layer is very dense, and nearly homogeneous
but e\'ident traces of cells are occasionally to be met
with.
^lost of the Solen tribe are littoral, and live in
sand which they penetrate for that purpose ; a few are
found at varioas and often considerable depths of water,
and these prefer a more muddy habitat. None of their
remains have been discovered in any geological formation
older than the lower tertiaries.
Genus I. SOLECUR'TUS ^ De BlainviUe. PL I. f. 1.
Body oblong, compressed : 'mantle capable of being inflated
in front : tuhes partly separated, extended, and occasionally
strangulated, issuing from a common sheath : foot tongueshaped, of an enormous size.
Shell resembling in shape a kidney bean, rather solid, nearly
equilateral, concentrically striated or sculptured diagonally
with imbricated ribs : teeth, two cardinals in the right valve,
and one in the left ; laterals short and rudimentary : jxiUial
scar ha\'ing a broad and shallow fold.
For the reasons which I have given in the last volume
(pp. 327 and 434), with respect to the systematic value
of characters derived from the separation or union of
the pallial tubes, I prefer not placing this genus and
Ceratisolen in one family, and Solen in another. The
relations of Ceratisolen to Solen, through S. pellucidus,
are too close to warrant their being assigned to different
families, and the transition from the last-named species
to >S'. ensis is very slight arul gradual.
* A .short Solen.
SOLEXID.E.
form elongated prisms, ^\'ith walls as straight and parallel
as those of Pinna ; but their axes are nearly conformable
with the surface, cropping out somewhat obliquely upon
the exterior, w^here their rounded terminations with
distinct nuclear spots may sometimes be seen. The
internal layer is very dense, and nearly homogeneous
but e\'ident traces of cells are occasionally to be met
with.
^lost of the Solen tribe are littoral, and live in
sand which they penetrate for that purpose ; a few are
found at varioas and often considerable depths of water,
and these prefer a more muddy habitat. None of their
remains have been discovered in any geological formation
older than the lower tertiaries.
Genus I. SOLECUR'TUS ^ De BlainviUe. PL I. f. 1.
Body oblong, compressed : 'mantle capable of being inflated
in front : tuhes partly separated, extended, and occasionally
strangulated, issuing from a common sheath : foot tongueshaped, of an enormous size.
Shell resembling in shape a kidney bean, rather solid, nearly
equilateral, concentrically striated or sculptured diagonally
with imbricated ribs : teeth, two cardinals in the right valve,
and one in the left ; laterals short and rudimentary : jxiUial
scar ha\'ing a broad and shallow fold.
For the reasons which I have given in the last volume
(pp. 327 and 434), with respect to the systematic value
of characters derived from the separation or union of
the pallial tubes, I prefer not placing this genus and
Ceratisolen in one family, and Solen in another. The
relations of Ceratisolen to Solen, through S. pellucidus,
are too close to warrant their being assigned to different
families, and the transition from the last-named species
to >S'. ensis is very slight arul gradual.
* A .short Solen.