230 
Pliny (Lib. xxxvn. Cap. 57,) who describes certain stones, some of 
which were white and others brown ; the former bearing in their 
figures, some resemblance to the male, and the latter to the female, 
parts of generation. These bodies were next noticed by Agricola, De 
Nat. Fossil. Cap. xi. as having been found whilst digging near the 
fortress of Ehrenbreitstein, 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, however, for a time, opposed by Henckell, who even 
doubted of their animal origin, but afterwards very candidly ac- 
knowledged the force of Wolfart’ 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 structure, 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 comprises the imperforated shells, with one valve flat, and a 
straight, extended, 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, towards 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, 
