258 



Fig. 11, is one figured by Scilla; and each exactly agree, in form, with 

 those of the recent fish both of Scilla and of Spallanzani. 



It is worthy of observation, that the triangular Glossopetrre are never 

 found attached to any bony substance ; a circumstance confirming the 

 opinion of their having originally been the teeth of fishes of the genus 

 Squalus. The teeth of this genus, as has been some time since remarked 

 by Scilla, and very lately by Spallanzani, not being placed in bony 

 sockets, but implanted in a hard and fungous flesh ; and which, decay- 

 ing by putrefaction, allows the teeth to become detached. 



Conichthyodontcs striati. These rare fossils are very exactly described, 

 by M. Walch, as being of a conical form, round on all sides, with the 

 superior termination, as it were, truncated ; and the whole surface of the 

 teeth so covered with longitudinal striae, as to give them somewhat of 

 the appearance of a Dentalite. These are sometimes found in the quar- 

 ries of Chippenham, and of other parts of Wiltshire and Oxfordshire. 

 One of these fossils is represented Plate XIX. Fig. 4. 



The straight or slightly bent conical teeth, Conichthyodontes recti teretes, 

 have been termed Plectronit& and Rostragi?ies ; and, indeed, are fre- 

 quently called birds' bills by the quarrymen who find them. Plate XIX. 

 Fig. 8. 



The teeth of which I have hitherto spoken may be considered as being 

 of the class of Incisores, and as being of the most decided kinds. There 

 are others, which differ from these in their forms ; but so little, as not to 

 require further notice here : such are those, which display little degrees 

 of variety of curvature, or which have suffered some change of figure 

 from accident. 



The molar teeth, which are placed in the back part of the jaws, and 

 even on the palate and in the back part of the fauces, are the next 

 subjects for our examination. These have been long known in their 

 mineralized state ; and some of them, for their imaginary virtues, have 

 been held in very high estimation. These are the fossils generally known. 



