233 



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 ; this, being lodged in the remains of 

 a shell, in tfie 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 Linnaean 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 



VOL. III. H H ' 



