199 
which it is marked, I am disposed to consider as P. campechensis, 
List. Conch. Tab. 432, Fig. 2/5. 
CXXVIII. Fistulana. An equivalved bivalve, gaping, nearly 
toothless shell, included in a club-formed testaceous tube, open at the 
smaller end. 
The bivalve of the Fistulana, as may be seen by its representations, 
Plate XIV. Fig. 2 and 4, bears a considerable degree of resemblance 
to the valves of Modiola : and it should be recollected, that some of 
the Modiola:, Mytilus Lithophagus, Linn, for instance, are found in 
cavities formed in stone. The tube of the Fistulana is completely 
closed at its larger end ; whilst the smaller end is open, and has 
sometimes one side of it formed by one of the valves adhering to it. 
We are much indebted to M. Faujas St. Fond for his researches 
respecting these fossil bodies, and for ascertaining the existence of 
these bivalves in their proper tube among the fossils of Grignon. 
Lamarck describes four species of this genus as found fossil in the 
neighbourhood of Paris : F. ampullaria, F. tibialis, F. echinata, and 
F. personata. 
The first of these, F. ampullaria, the tube of which is of the form 
of an elongated pear or bottle, and covered by a calcareous sand, has 
two ridges in the inside of its smaller part ; and in this part is found 
the bivalve shell, resembling one of the modiolas, and with a shining 
surface. The shell is sometimes found loose, and at other times 
united to the tube by interposed spathose matter. 
Mr. Meade very kindly favoured me with the two shells of this 
genus, detached from their tubular parts, the representations of which 
have been just referred to. The same gentleman also obliged me with 
a mass of spathose lime-stone, in which several of these fossils are 
imbedded, with their containing ampullaceous tube. PI. XIV. Fig. 6. 
The fossil which is figured, Plate XII. Fig. 1, of the second volume 
of this work, to show its coralloid investment, as well as the ampul- 
laceous bodies in Fig. 2, of the same plate, belong to this genus, and 
doubtlessly contain the two valves composing the shell ; but here, as 
