Structure of the Scales of Fishes. 289 



tions made by me on the struetm'e of the scales of fossil fishes. 

 I shall now, however, limit myself to the statement of the 

 mere general results of this inquiry, the details of which, ac- 

 companied with numerous figures, I propose to give in a me- 

 moir soon to be published. 



M. Mandl alleges that I am mistaken in affirming that 

 scales are composed of superimposed plates. He assures us, on 

 the contrary, that they are formed of cells placed near each 

 other. He even attempts to demonstrate this in the scales of 

 the roach ; and yet, in this very fish, I have succeeded in se- 

 parating the plates of growth from each other, whUe, in nu- 

 merous transverse sections of difi'erent scales, 1 have seen, 

 with a magnifying power of 250 times the diameter, the super- 

 position of these plates throughout the whole thickness of the 

 . scales. I have even already published a figure of such a sec- 

 tion of the scale of Salmo Trutta, in my Natural History of 

 Fresh-water Fishes. 



M. Mandl afterwards afiirms, that the divergent rays on the 

 surface of scales which I had described as furrows, are true 

 canals. I dare scarcely allow myself to believe, that M. Mandl 

 has confounded the median tubes of the scales of the lateral 

 line (which sometimes ramify to their posterior extremity) 

 with the furrows of their surface ; this would be to impvite to 

 him too gross an error ; and yet I can perceive no other ex- 

 planation of what he states. This much, however, I can po- 

 sitively affirm, that the other scales never have canals on their 

 surface, but rather furrows interrupted above, and which are 

 prolonged from the edge of a superior plate of growth, to the 

 edge of the inferior one following, as is evidently shewn by 

 every transverse section which can be made on any scale what- 

 ever which presents such rays. 



M. Mandl further alleges, that the teeth of the posterior 

 edge of pectinated scales are not notches of the edges of their 

 lamella;, but true teeth having a root enveloped in a sac. It is 

 sufficient to examine the scales of the Scienes, which M. Mandl 

 brings forward as an example, witlidrawing and approaching 

 the scale successively to the focus of tlie mici'oscope, to be con- 

 vinced, that all this pretended dental apparatus is nothing more 

 than an optical illusion, resulting from the difference of the 



