*74 
Mr. Griffiths's Description 
EXPLANATION OF THE DRAWINGS. ( Plate X.) 
Fig. i, Is a representation of the whole shell in the most 
perfect state in which its parts have been seen, and there 
is reason to believe that the only part wanting is the orifice of 
the double tube. The drawing is made upon a scale of 21- 
inches to a foot. 
Fig 2, A drawing of the small termination of the shell. 
At its lower part, for an inch in length, it exhibits the usual 
appearance of the external surface, but from thence to the 
end, it is very irregular, and in some specimens small shells 
of oysters, small serpulae, &c. adhered to it. All this surface 
was probably above the mud, exposed to the sea water. At 
the upper extremity one of the tubes is broken, shewing the 
size of its canal, also that it is connected with the outer tube 
in which it is inclosed. The other tube is a little bent, and 
diverging outwardly, and this is probably its natural termi- 
nation. 
Fig. 3, Represents a section of the shell, at that part 
where it forms a double tube, to shew the origin of the two 
tubes, the thickness of the septum between them, and the 
two orifices leading into them. 
Fig. 4, Is a transverse section of the shell at the thickest 
part, after it had been polished, to shew that it is made up of 
strata of crystals surrounding one another in concentric circles ; 
also a front view of the orifices into the double tube. 
Fig. 5. A front view of the orifices into the double tube, 
also shewing the thickness of the shell at that part, the canal 
of which has an oval form. 
