66 Couthouy's New Species of Mollusca 
transverse plate, from each side of which arises a third 
narrow rib, which, curving a little inwards for about one 
third the length of the valve, there forms two branches 
diverging toward the middle of it, where they unite in 
such a manner as to form a slightly gibbous, oval ring 
about one eighth of an inch in diameter; the whole of 
this internal support is unconnected with the shell any 
where, save at the hinge. Viewed under a microscope, 
the valves exhibit a multitude of minute points or dots 
arranged in quincunx. 
Ozservations. I am indebted for the specimen of 
this delicate shell, from which the foregoing description 
was made, to the kindness of W. W. Wheildon, Esq., 
of Charlestown, Mass., by whom it was taken from the 
stomach of a haddock, in deep water, off Nahant. I have 
been informed by Dr. A. A. Gould, that the same spe- 
cies was found, a year since, in Lubec Bay, by Dr. C. 
'T. Jackson, during his geological survey of the State of 
Maine. It is therefore probably an inhabitant of deep 
water on the whole New England coast. I have seen 
in the possession of Dr. Jay, a specimen of this shell 
more than twice the size here given. Its color bordered 
more on the cinereous, and the valves were slightly ele- 
vated in the centre, from the apex to the margins. Lo- 
cality unknown. 
I was at first inclined to the belief, that the emargin- 
ate, open appearance of the tendinal orifice, was owing 
to the loss of the accessory pieces, which should have 
rendered it circular; but from subsequent examination 
of several other specimens which were perfectly fresh; 
and one of which had the animal still undecomposed in 
it, am now satisfied that it is a true character of the 
shell. So far as I can ascertain, there is no doubt this 
is an unedited species. 
