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satisfied, from having cleared away this specimen very close indeed to 
the beaks, that there was no opening in the hinge between them. 
The fossil Plate XVI. Fig. 13, which is a specimen from Mr. For- 
ster’s collection, first excited my attention to the peculiar structure to 
which I have alluded. It is a tubular body, spirally disposed, in the 
form of a cone, curved at its apex ; which is lodged in the remains of 
a shell, in the angle at the side, where the upper and lower margins 
united, a part of this tube going off from the base towards the opening 
of the valves at their upper margin. The tube itself is beautifully frosted 
over with quartz crystals, and the matrix in which it is imbedded is 
chert. From two or three casts, and from several impressions in the 
mass, I was convinced that the shell in which this body was inclosed 
was of the Linnasan genus Anomia; and, reasoning from the proportions 
of that part of the shell which remained, I was surprised at finding that 
this body must have filled nearly one half of the shell. 
After rubbing down and breaking many different shells without suc- 
cess, I found the same structure, but badly shown, in two shells, one of 
which was about the size of that in the above specimen. At length, I 
was so fortunate as to discover traces of it in a larger shell of the same 
species ; and, by breaking away a considerable part of the smaller valve, 
and of the spathose matter contained in the shell, was enabled to display 
it as shown Plate XVI. Fig. 11. With respect to the shell itself, like 
A. striata of Martin, it has a hinge straight, extended and patulous, valves 
convex, semicircular, and longitudinally striated on every side. In the 
smaller valve is a convex wave, which is answered by a scarcely distin- 
guishable concave one in the larger valve. In a word, were it possessed 
of a large triangular opening between the beaks, it would then possess 
all the external characters of that species. 
The structure of this particular part seems to point it out as an organ 
of attachment, and perhaps of motion. Supposing this to have been a 
strongly elastic cartilaginal tube, and that the animal possessed the power 
of uncoiling and extending it so as to be able to fix its end to some firm 
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VOL. III. 
