Recherches sur les Poissons Fossiles. 



71 



the Scleroderms; the GymnodontSi the Lophobranchs, the 

 Goniodonts, the Silures and the Sturgeons. 



Third Order : The Ctenoides. — If we reflect on the strik- 

 ing difference of form which we sometimes observe in the 

 genera of this same family, we will not be surprised to find 

 united in the group, families whose external aspect is very 

 variable. The most numerous have the scales formed of 

 laminae having the posterior border pectinated, that is to say, 

 the hinder part of the border which is visible. The numer- 

 ous layers, which are superimposed one to another overlap 

 so, that the inferior lamina projects always beyond the 

 superior, so as to cause the scales almost to touch. This 

 structure is particularly perceptible in the Chetodons and 

 Pleuronectes, so that they seem as if placed too near to each 

 other. It is here that we place the Perco'ides, the Polya- 

 canthes, the Scieno'ides, the Sparo'ideSf the Scorpeno'ides, 

 and the Aulostomes, 



Fourth Order : The Cycloides. — The families which be- 

 long to this order, have scales formed of simple plates, and 

 the borders plain, which does not prevent their external 

 surface from presenting occasionally a great variety of 

 colours on the outer surface of the laminae of the scales. 

 The scales of the lateral line are formed like all the others ; 

 but in place of the flat plates, there are channels placed 

 one to another, and extending backward against the disc of 

 the scale, form a tube from which the mucus, which covers 

 the body flows. This tube is sometimes bifurcated, and 

 sometimes ramified. Here we place the Lahro'ides,^' the 

 Muges,^ and the Atherines,% the Scomber o'ides,^ the Ga- 

 doides,|| the Goboides,1f the Murenoides,** the Lucioides,f f 

 the Salmons, the Clupes,H and Cyprins.§§ 



* The Wrasse family, f Mullets. X Sand Smelts. 



§ Mackerels. || Codfishes. ^ Sea Gudgeons. 



** The Eels. ft The Pikes (?) U Herring family. 

 §§ The Carps.— Ed. 



