Classification of the Ganoids. 331 



ance with tlieii' affinities and the totality of their cliaractcrs, 

 species by species and tj^enus by genus, until the families arc 

 formed ; and then, by bringing together the families in the 

 same manner, without any ])reconceived idea, we shall succeed 

 by degrees in establishing groups of a higher order, and finally 

 see rise before us the true natural system, the subdivisions of 

 which will rest upon the solid basis of experience and the 

 totality of the facts. We must tlierefore, y)rovisionally at least, 

 limit the name of Ganoids to the indubitable existing types 

 (that is to say, the Lcpidosfei and Polt/pteri) ^ and to the fossil 

 types which will naturally group themselves around these, by 

 giving proofs of their affinity rendered incontestable by the 

 absolute concordance of important characters ; whilst we must 

 in flie same way eliminate, at least provisionally, all the forms 

 between Avdiich and the ])receding our com])arativc synthetic 

 method shall ])rove incapable of establishing any bond of 

 relationship. The picture which the suborder Ganoidei will 

 present to us afters scrupulous investigation of this kind will 

 be nearly as follows : — 



I. First series.' — The Lepidosteid(e or Eugano'idei will in- 

 clude the fishes with bony, enamelled, rhomboidal, and articu- 

 lated scales, related to the existing Lepidostei^ and possessing 

 neither the dermal ribs of the Leindopleurida-^ nor the fringed 

 or oar-like paired tins of the Pohjpterida>.^ nor the gular plates 

 which take the place of the brancliiostegal rays in tlie latter*. 

 Although ap])arently forming a very natural group, there is no 

 positive peculiarity which characterizes these in an absolute and 

 exclusive manner. As regards the scales of the body, they 

 possess characters common to a portion of the Polypteridxu • 

 the so-called fulcral scales of the margins of the fins, which 

 occur at least in the majority of the fossil Lepidosteida'^ occur 

 also in the ancient Lcpidopleurida'., and even in some true 7f> 

 leostei of the Jurassic period ; leaving out of consideration the 

 living Lepidostetj the fossil Lepidosteidcc appear to have had a 

 common character in the delicate and numerous rays of the 

 fins and brancliiostegal membrane ; lastly, the forward position 

 of the ventral fins u])on the middle of the belly Avill also dis- 

 tinguish them from the Polypterida', with similar scales. 



Although this series embraces a very great number of 

 genera, the greater part of which will be found mentioned in 

 my memoir, it seems to me to be impossible to subdivide it 

 naturally into tribes or families. We might perhaps distin- 



* With tlic Sdlc exception of Clieirolcpin, the ouly Devonian tj'pe of the 

 •whole series whioli inilicates by its gular plates a certain relationship to 

 the contemporaneous Polypteridse. 



