one end was, pierced externally with several small holes placed in a regular order, which probably communicated with the tubuli I have mentioned, and by the contraction and dilatation of which the animal was enabled to draw in the water from which it extracted its nourishment.
Besides these extraordinary shapes which projected in relief, I observed a variety of very regular white figures as if painted upon the rock, being even with its surface, Pl. 29, fig. 12. They consisted of circles, of ellipses with various eccentricities, and of parallel lines, both straight and curved. These I considered to be the different sections of some cylindrical and perhaps tubular bodies inclosed in the stone: the figures being always such as would be produced by the various sections of a hollow cylinder both straight and crooked. The circles were generally from two inches to half an inch in diameter, and were of a whitish yellow colour, the rest of the stone being of a greenish yellow, or greenish brown. They were smooth on the inside, but the outside was radiated, as if the original body had been covered with spiculæ.
The substance which filled up the area of these figures was generally the same as that surrounding the outside, but sometimes it was a little different.
Although I had no doubt but that these singular figures owed their origin to some organic body, yet I did not at first suspect that they were in any way connected with the cylinders in relief that I have just described. Fortunately however an illustrative specimen in the limestone convinced me that both these appearances so different from each other were derived from the same source. Pl. 29, fig. 13, represents the specimen to which I allude. In this on one side may be seen a perfect example of the white radiated circles, and, in consequence of some of the stone being broken away, the in-
