78 



larly up this central projection, to where it has been broken off: this is 

 formed by two flattish turns, which, on their upper surface, are marked 

 by slight longitudinal rugae, which terminate in two ridges, disposed on 

 the inner and on the outside of each turn. These turns, on the lower 

 side, are roundish, and are very thickly set with sharp and irregular 

 rugae, and seem to form a concavity nearly corresponding to the eleva- 

 tion on the other side ; but in this concavity an irregular shelly body 

 exists, which appears riot to be accidental, but a part of the original 

 shell. Fig. 7 represents the under part, with this irregularly formed 

 bod}r, and Fig. 8 represents the upper surface, with its projecting cen- 

 tral termination. An endeavour is made to give a representation of the 

 aperture of this shell, of which description could hardly have given a 

 satisfactory idea ; indeed, it is so much obscured by the surrounding ma- 

 trix, as to prevent a correct figure of it being obtained. The matrix of 

 this fossil is a yellowish lime-stone, with which the hollow of the shell is 

 completely filled. 



The fossil, Plate V. Fig. 18, which appears to be of the same genus with 

 the two preceding, is so figured, as to show a portion both of its upper and 

 under part. On the former, the turns of the spire are seen covered with 

 closely-set transverse ribs, the spire terminating in a roundish projection. 

 The turns of the spire are ribbed in the same way on the under side ; and 

 here a projecting shelly body is seen in the concave part, answering, in 

 its situation, to the irregular formed body in the preceding fossil ; and 

 to the projecting superior termination of the spire in the same fossil, in 

 having the markings of the spiral turns continued upon it. 



It would be premature, to attempt to establish a genus for the. recep- 

 tion of these fossils, until more particulars are ascertained respecting the 

 original size and real nature of the projecting bodies which appear to 

 belong to both the upper and under surface of these fossils. Should the 

 appearance of these be found to be constant, that alone would, of course, 

 form a generic distinction. 



