89 



whetstone, which still fills its matrix, Plate VI. Fig. 2. It is so tho- 

 roughly silicious, as to be transparent, where the matrix is not interposed, 

 Plate VII. Fig. 2. 



Lamarck describes three species of this genus as French fossils : N. la- 

 bellata, N. epiglottina, N. cepacea. 



LXI. Testacella. An obliquely conical formed univalve, with the 

 summit a little turned spirally ; the opening oval, with the right edge 

 turned inwards. 



LXII. Stomatia. An oval auriform univalve, with a prominent spire : 

 the opening ample, and longer than wide ; the disk imperforate. 



LXI II. Carinaria. A very thin univalve, in the form of a cone flat- 

 tened on its sides, the apex terminating in a very small involuted spire, 

 and the back having a dentated keel : the opening entire, oval-oblong, 

 contracted towards the angle of the keel. 



No remains of any shells of the three preceding genera have, I be- 

 lieve, been found fossil; nor are the inhabitants of the two latter shells 

 known. 



LXIV. Haliotis. A flattish, ear-formed shell, with a depressed spire, 

 and a row of round holes along the right edge. The opening very large, 

 and much longer than wide. 



M. Bosc observes that these shells are often found fossil in France and 

 Italy. On this point I am obliged to observe, that, from the informa- 

 tion which I have gained, from the sight of different collections, and 

 from the examination of different authors, I conceive the contrary of 

 this to be the fact. Indeed, of the seventeen species which M. Bosc 

 enumerates, he mentions but one species, Haliotis plicata, as having been 

 found fossil. I do not indeed, therefore, hesitate in saying, that the 

 shells of this genus are among the rarest fossils. 



The nearest approach to this genus is a shell which is sometimes 

 found among the fossils of St. Peter's Mountain, and has been hitherto 

 considered as a Haliotis, but which certainly belongs to the following 

 genus, which differs from Haliotis, in being without holes. 



VOL. III. N 



