ipedes, and that the other
two, near the eye, answered to the scuta. The valves being of unequal
sizes on the right and left-hand sides of the animal, is probably
connected with one side being pressed against the hard, shelly valve of
the female; in the same way as the valves in certain Paecilasmas; are
smaller and flatter on the side nearest to the crustacean to which they
are attached. The eye, in being slightly notched on the upper and lower
edge, shows signs of really consisting of two eyes, which I believe is
always normally the case; it is rather larger, in the proportion of 13
to 11, being 13/12,000 of an inch in diameter, than in _S. vulgare_; and
from the almost perfect transparency of the integuments, is far more
conspicuous than in that species. Hence when the valves of the female
are opened, the black little eye is the first part of the male which
catches the attention. No vestige of a mouth could be discovered.

_Thorax and Abdomen._--The thorax, as in _S. vulgare_, is highly
extensible, and when stretched exhibits the same five transverse folds
or articulations; when contracted, it is broader, so that even the
truncated end of the abdomen is wider than the lower (properly anterior)
end of the thorax in _S. vulgare_. Its thin outer integument is studded
with excessively minute points in transverse rows. The four pair of
limbs are longer than in _S. vulgare_, but the spines on them much
shorter and thicker; each limb (including the first) supports three
spines, of which one is seated on a notch low down on the outside, and
is longer than the other two; of these two, the one on the same side
with the notch, is a little longer than the other. The spines on the
first and second pair of limbs are considerably shorter than those on
the third pair, and these latter, are a little shorter than those on the
fourth or posterior pair. Hence, the spines on the thoracic limbs,
compared with those of _S. vulgare_, present considerable differences,
both in their relative and absolute dimensions. The abdominal lobe is in
proportion rather shorter; its end is less abruptly truncated, and
supports a row of, I believe, six moderately long, and basally thick
spines; these spines are not so long as those surmounting the fourth
pair of limbs. On both lateral margins of the abdomen, rather on the
ventral face, there is a row of, I believe, seven long spines, but it is
very difficult to count the spines in specimens which have been