ANALOGIES OF THE APODAL OEDER. 217 



It is somewhat singular that the first, third_, and fifth 

 of these analogies are more clear than the intervening 

 ones : and yet this very circumstance, instead of weak- 

 ening, rather tends to strengthen, the probability of the 

 whole being correct ; for it cannot be doubted that M. 

 Cuvier is perfectly right in placing Gymnarchus imme- 

 diately after Murcena: and as all writers, ancient and 

 modern, agree in the opinion that the lampreys and the 

 Myocene, of all fishes, are those most allied to worms, 

 so they become the most aberrant of the order. Again, 

 the skeleton of Myxene is so slight, that it is not even 

 cartilaginous ; while that of Liparis, among the Cyclo- 

 pteridcB, is equally imperfect, being almost gelatinous. It 

 may be further remembered, that very small eyes is one 

 of the characteristics of the cheloniform type ; witness 

 the whole of the BalistidcB and the ChironectidcB, nu- 

 merous genera of the SiluridcB, &c* : now this limited 

 vision is carried to its highest zmperfection in the lam- 

 preys; for some of the genera are actually blind, having 

 no eyes whatever. Finally, of all the apodal order, 

 length of tail, which is one of its primary character- 

 istics, is especially developed in Sternarchus, so named, 

 because, although it is a long fish, the anus is close to 

 the sternum. Nevertheless, we wish it to be remem- 

 bered on this, and on all other occasions, that analogies 

 (however necessary to the confirmation of an arrange- 

 ment supposed to be natural) are of inferior importance 

 to affinities. 



(191.) In regard to the situation of Petromyzon, 

 which we have removed from the Cartilagines , it is quite 

 clear that no one would have arranged it in the same 

 order with sharks and rays, but for the similarity of its 

 branchia. Now, if this part of its structure is really of 

 such importance as to decide its place in nature, it 

 may be fairly asked. Why is not this absolute rule acted 

 up to in the case of Myocene, whose branchial apertures 

 are like those of the eels? These two genera cannot be 

 separated : and is not Myxene infinitely more allied, in 

 all parts of its structure, to Gymnarchus^ than Petromy- 



