200 
in many other specimens, the included valves are most probably 
involved in spathose matter, which has crystallized within the tube. 
Plate XIY. Fig. 1S a yer J instructive specimen of this shell : the 
valves being there seen partly denuded of their including tube. This 
specimen I purchased from the Museum of Dr.Menish. It was found at 
Bradford, Wilts, in the white clay which covers the great Oolite rock. 
I have now before me a fossil of this species from Malta, of which I 
have opened one side so much, as to give a pretty fair view of one 
of the valves, which is very nearly two inches in length, and has a 
very smooth surface. This shell evidently differs from the Bradford 
shells, Fig. 2 and 4, which again differ from each other, they forming, 
as it were, sub species. I have been favoured with calcareous masses, 
in which these fossils are imbedded, from Bedfordshire, by Mr. Good- 
hall and the Rev. Mr. Marsh ; and from Wiltshire, by Mr. Cunnington. 
In the F. tibialis, which is much larger than F. ampullaria, one of the 
valves is found adhering to one side of the tube. This valve is marked 
withunequal transverse strife , which a magnifying glass shows are decus- 
sated by longitudinal, and sometimes punctuated strife. The lower part 
onlyof this tube has been seen by Lamarck; and this seems to bear some- 
what of the general form of the preceding species, although much larger. 
In F. echinata, the bulbous end of the tube is irregularly beset with 
tubular points. On one part of its surface, which is bounded by a 
fringe of these spines, there occurs a small smooth space, and then 
another surface, beset with spines. On the other side, one of the 
valves is detected, set in the side of the tube. This valve, though 
apparently smooth, is discovered, by the glass, to be beset with minute 
scaly points, disposed in rows, directed towards the beaks. This fossil, 
as well as the other, was found at Grignon. 
F. per sonata is very remarkable for the form in which its larger, or 
clubbed end, terminates. The tube, which is cylindrical in great part 
of its length, is seldom more than two or three inches long ; becoming 
small at its open end, and being somewhat rounded at the other. At 
this larger termination it is closed, rounded, and very obtuse ; and on 
