94 



duced in a perpendicular direction; the termination, containing the 

 aperture, which is round, standing upwards. It is from the neighbour- 

 hood of Verona. 



Plate VII. Fig. 4, is a small serpulite, the turns of which are spi- 

 rally disposed on a horizontal plane, excepting the last ; which, as in 

 the preceding fossil, turns upwards. 



The Kentish chalk fossil, Plate VII. Fig. 11, is a serpulite of a 

 very curious form and character. It is formed of four spiral turns, the 

 last of which is carried out a little way in a straight line, and then appears 

 to have had its termination marginated. From its aperture another 

 tubular body appears to have proceeded, the inferior part of which 

 closely imitates, in its general appearance, the fringed, rugous, flat 

 disc, serving as the foot of the snail. This also terminates with a 

 marginated ring, forming a round aperture. The whole surface of 

 the shell is marked by very fine transverse striae ; and at distances, 

 increasing as the shell has grown, distinct annular projections are ob- 

 servable. 



The extraordinary form of this shell, and particularly the appearance 

 of that part, which, though it must always have been oi a shelly 

 hardness, bears so close a resemblance to the soft rugous part of the 

 snail, led me very anxiously to seek for opportunities of examining its 

 internal structure. I at last obtained two other specimens; and then 

 found, on carefully breaking them, that at each of these annular pro- 

 jections, and at that part where the shell seems to commence anew, a 

 close internal septum existed, which presented externally a concave 

 surface, and which prohibited any communication of the chambers with 

 each other, or with the animal, which doubtlessly lived only in the last 

 formed chamber. 



In this fossil we first observe a peculiarity of formation, which, as far 

 as my knowledge extends, has not yet, although known to exist in 

 several instances, obtained that attention which it seems ta demand. 

 In the nautilus, it is generally believed, that the division of the shell 



