ae 
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XX. A Defcription of ibe Teeth of the Anarrhichas Lupus 
‘Linnxi, and of thofe of the Cheetodon nigricans of the fame 
Luthor; to which 1s added, an Attempt to prove that the 
Teeth of cartilaginous Fifbes are perpetually'renewed. By Mr.. 
William Andre, Surgeon; communicated by Sir Joteph Banks, 
Bart. P. R.-S. 
Read March 18, 1584, 
HE amazing variety there is in the external form of 
fifhes muft be obvious to a‘:common obferver; and who- 
ever examines will be convinced, that the fame variety pre- 
vails in their internal flrugture. No parts, perhaps, afford’a 
more convincing proof of the laft affertion than the teeth of 
fifhes. ‘To adduce a few inftances, let us only recolleé the 
tuberculated teeth in the ‘thorn-back; the triangular ferrated 
teeth in the fhark ; the flender flexible teeth in the ch@todontes, 
or angel-fithes. There is not only a difference of their form, 
but alfo in the fubftances of which they are compofed; fome 
being of afoft horny nature; others made up of bone; others 
of that fubftance we call enamel in the teeth of quadrupeds’s 
and fome having the apparent hardnefs and ‘tranfpareney of 
cryftal. We may alfo notice their uncommon fituation ; “many 
fifhes having teeth not only in their jaws, but on the tongue, 
the palate, and about the fauces. 
To illuftrate in fome degree this part of natural. hiftory, I 
fhall defcribe the teeth of the Anarrbichas Lupus, or Sea- 
wolf, and thofe of the Chetodon nigricans, a fpecies of 
Angel- 
