42 Prof. Owen on the Structure of the Teeth of some Fossil Fish. 



like substance ; but tliis is not true enamel, nor the product of a 

 distinct organ ; it differs from the body of the tooth only in the 

 greater proportion of the earthy particles, their more minute dif- 

 fusion through the gelatinous basis, and the more parallel ar- 

 rangement of the calcigerous tubes ; but it is developed in and 

 by the same matrix, and resulting from the calcification of its 

 external layer, is the first part of the tooth which is formed" 

 (p. 8). I then go on to cite the fishes that have true enamel, 

 developed from a distinct organ (p. 9) : and the modifications of 

 the enamel-like dentine are described at pp. 34, 54, 56 et pas- 

 sim^. To most of the modifications of dentine in fish-teeth I have 

 assigned and published names, e. g. ' osteodentine, ' ' vasoden- 

 tine,' ' plicidentine,^ ' dendrodentine,^ Mabyrinthodeutine^t : if 

 it be really requisite to give a name to the modification of hard 

 dentine above defined, I would suggest to Mr. M'Coy the de- 

 sirableness of adhering to the terminology already in use. The 

 term ' ganoine ' is required for the enamel-like tissue of ganoid 

 scales, and that of ' vitrodentine ' would have been the one I 

 should have proposed for the tissue which I believe myself to 

 have first defined, had I not been checked by the observation of 

 the very gradual passage of hard or true dentine into it in many 

 fishes, and by the natural desire to reduce the number of new 

 terms to the minimum which the exigences of science seemed to 

 require. 



From the terms of the descriptions quoted from the ' Annals 

 and Magazine of Natural History,^ 1848, p. 124, and from the 

 ' Proceedings of the Cambridge Philosophical Society ' for June 

 1848, anatomists might be led to cite the subject of them as the 

 ' ganoine of M'Coy / but I am sure that gentleman is above the 

 device by which small zoologists, of what our plain-speaking 

 German brethren call the ' Gattungsmacherei,^ endeavour to ap- 

 propriate a new species discovered and defined by another, by 

 the mere imposition of a name. 



I remain. Gentlemen, your very obedient servant, 



Richard Ow^en. 



* The texture of the tooth of Ctenodiis is described as presenting " a 

 coarse osseous structure at the base, supporting a dense osseous or enamel- 

 like layer," p. 63. Although in defining the obvious external characters of 

 the tooth of Petalodus the term ' enamel ' is used, I am careful, in describing 

 the structure, to state that " the short terminal branches of the medullary 

 canals, which distribute the calcigerous tubes to the enamel-like outer layer, 

 are slightly bent downwards," &c., p. 62 : so that after the previous defini- 

 tion of the ' enamel-like ' substance at p. 8, no mistake could be made. 



t ' Odontography ' and ' Lectures on Vertebrata,' tom. i. p. 226. 



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