230 



ration. These bodies were next noticed by Agricola, De Nat. Fossil, 

 Cap. xi. as having been found whilst digging near the fortress of Ehren- 

 breitstein, in Treves. After various opinions had been offered respecting 

 the origin and nature of these bodies, Wolfart, Histor. Natur. Hass. 

 infer, p. 30, advanced the opinion, that the latter of these fossils were 

 the casts of a peculiar kind of marine shell. This opinion was, how- 

 ever, for a time, opposed by Henckell, who even doubted of their ani- 

 mal origin, but afterwards very candidly acknowledged the force of Wol- 

 fart's arguments. 



These curiously formed fossils are now known to have derived their 

 figure from the internal structure of shells of this kind: in many of which 

 I perceive a peculiar conformation entering far into the shell, apparently 

 adapted to support the termination of the cartilage which the animal 

 extrudes, and which structure would be a mould, in which a similar body 

 might be cast. The beak of one of these shells, with this particular struc- 

 ture, is shown Plate XVI. Fig. 20. 



I will now call your attention to those shells which Mr. Martin found 

 it necessary to place in two families distinct from those which comprise 

 the shells which we have just examined. The first is, that which com- 

 prises the imperforated shells, with one valve flat, and a straight, ex- 

 tended, and narrow hinge. 



The most extraordinary, perhaps, of the imperforate shells, is Ano* 

 mites productus, of Martin, the larger gibbous valve of which is lengthened 

 out in a cylindric form, and longitudinally striated; the striae close, equal, 

 and, toward.: the margin, dichotomous : the margin itself somewhat 

 sinuous and irregular. In many specimens, the upper part, particularly 

 near the beak and hinge, is set with a few distant tubercles; the beak 

 small and pointed. The other valve is small, semicircular, and concave, 

 clasped or surrounded by the larger valve, and longitudinally and some- 

 times transversely striated. 



Its most striking characteristic is, the lengthened cylindric form of the 



