PANOPADA. 163 
the foot is very small; the tube is of large diameter, and, 
when fully extended, is 7 inches long, fleshy, and covered with 
a dark epidermis, which gives it as rugose an aspect when 
nnder contraction, as that organ in Mya truncata; it forms 
near the extremity the two siphonal orifices, which are scarcely 
separated, the upper or anal one bemg rather the shortest ; 
they are both furnished with short, simple, white cirrhi, not 
digitated or fimbriated as in some of the Wye. The branchize 
are extensive, but not deep, well arcuated on the body, the 
upper plate lapping only on half the surface of the lower one ; 
they are very long, and after quitting the body, gradually taper, 
becoming linear, and are prolonged nearly to the extremity of 
the siphonal apparatus, terminating in acute points, and cannot 
be much less than 6 inches in length; the colour on the body 
portion is light drab, rather sparingly aspersed with minute 
bistre-coloured points; the pectinations on the part coasting 
the body are visible, but not strong; as they advance they 
become coarsely crimped or wrinkled. The anal and siphonal 
issues are not separated their whole length from the extremities 
to the body, by an impermeable wall, as in the Pholades, but 
only for an inch at the terminations, and then debouche into 
the main tube; the branchize in Gastrochena and Savxicava 
are of the same linear complexion, and similarly deposited in 
the main tube; the palpi are long, slender, delicate, pointed 
and triangular, united around the mouth, pale drab, very finely 
pectinated without, and smoother within. The body is of a 
thick oval mould, pale pinkish-drab, and from its centre a 
very small byssal-grooved foot proceeds, which, as far as could 
be judged, would, when exserted, produce a subcylindrical one, 
like that of Sawvicava and Gastrochena; it is certainly less 
hnguiform than in Mya, which also differs from it in having 
no byssal groove. The liver, as usual, is green. In other 
respects there is nothing peculiar in the aspect of the animal. 
There was no byssus in the groove of the heel of the foot. 
This species has not yet been found on our southern shores ; 
it has, however, been reported from Scarborough. The above 
remarks are from the examination of an adult animal sent us 
M2 
