332 Recherches sur les Poissons Fossiles. 



of the skin; that which is to follow in the superposition, 

 or the imbrication of the scales, appears to be free, and 

 is generally found to be so, whilst the anterior border is 

 covered by the preceding scale which advances freely in 

 its cellule. When we detach a scale from the body of 

 a fish, we necessarily raise the fold of the epiderm which 

 fixes it to its cavity, it is owing to this that at first sight 

 the posterior border of scales always appears so different 

 from the anterior border. W e have remarked in fact on the 

 external surface of each scale, or the part which advances 

 into the cellule, a great number of concentric lines so much 

 the more visible as they approach the centre. But when the 

 epiderm of the posterior border is raised, the lines are found 

 to be similarly concentric, and thus it is easy to see that the 

 concentric lines of the anterior and posterior borders are conti- 

 nuous with one another. After macerating the scales for 

 some time in common water, they appear to be easily 

 divided into a great number of plates or leaves, more or less 

 thick, and of different sizes, but which are all of the 

 form of the scales : these leaves are superimposed in such a 

 way, that the smallest occupies the centre of the scale, 

 and forms its outer part, whilst the larger succeeds the 

 smaller, successively, and is soldered to its inferior surface : 

 thus it is evident, that the concentric lines which are visible 

 on the outer surface of scales, are simply the borders of the 

 leaflets of which they are composed. Thus the reason why 

 the inner surface of scales should always be smooth is, 

 because the last leaf of which it consists, extends beyond the 

 borders of all the others. A correct idea of the structure 

 of scales may thus be formed by conceiving them to be 

 so many flat cones with broad bases, consisting of a succes- 

 sion of plates, the smallest occupying the summit, and the 

 largest composing the base of the cone ; only in represent- 

 ing them thus, it should not be forgotten, that it is the 

 summit of the cone which exists first, and thus it is by 



