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X. On the Development of the Teeth of Fishes (Elasmobranchii and Teleostei). 
By Charles S. Tomes, M.A. Communicated by John Tomes, F.R.S. 
Received March 1, — -Read April 15, 1875. 
The conformation of the jaws of the Elasmobranchii is such as to afford peculiar facilities 
for the study of the development of their teeth, and it has hence resulted that the older 
descriptions of the process approximate more closely to the truth than has been found 
to be the case in reptiles and mammals, and, I may now add, in osseous fish. 
The accounts given by Prof. Owen in his 4 Odontography ’ (p. 35) and 4 Anatomy of 
Vertebrates ’ (vol. i. p. 381) do not materially differ from one another ; I will therefore 
make an extract from the latter work as embodying as concisely as possible the views 
of that anatomist, which are generally accepted as correct : — - 
44 It is interesting to observe in it (the class of Fishes) the process arrested at each of 
the well-marked stages through which the development of a mammalian tooth passes. 
In all fishes the first step is the simple production of a soft vascular papilla from the 
free surface of the buccal membrane ; in sharks and rays these papillae do not proceed 
to sink into the substance of the gum, but are covered by caps of an opposite free fold 
of the buccal membrane ; these caps do not contract any organic connexion with the 
papilliform matrix, but, as this is converted into dental tissue, the tooth is gradually 
withdrawn from the extraneous protecting-caps, to take its place and assume the erect 
position on the margin of the jaw. 
“ Here, therefore, is represented the first and transitory 4 papillary ’ stage of dental 
development in mammals, and the simple crescentic cartilaginous maxillary plate, with 
the open groove behind, containing the germinal papillae of the teeth, offers in the shark 
a magnified representation of the earliest condition of the jaws and teeth in the human 
embryo.” 
My own observations do not enable me to verify in its entirety any portion of the 
above extract, some of the conclusions expressed in which had, indeed, already been 
challenged by Professor Huxley* in a paper published in the 4 Quarterly Journal of 
Microscopical Science ’ in 1853. 
* In the first part of the Philosophical Transactions for 1875 1 have already given a brief resume of the present 
state of knowledge on the subject of the development of teeth; and I have therefore incorporated in the text 
of the present paper references to those papers only which directly relate to the teeth of Pish. As, however, 
this paper will not appear in the same volume of the Transactions, I very gladly fall in with the suggestion that 
I should notice one or two salient points lately established as true of other teeth. 
Prof. Huxley (Quart. Journ. Micros. Sci. 1853), while accepting the views of Goodsir as true of mammalian 
teeth, combated the idea that all reptilian and piscine teeth were developed from free papillae ; Guillot (Anna!. 
MDCCCLXXVI. 
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