20 



by that zoologist, and has united the Marsipobranchii and Pharyngo- 

 branchii, which were believed by Miiller to form distinct subclasses, into 

 one order. The Lepidosirenoids are regarded as forming the ninth order 

 in an ascending rank ; on that order, the name of Protopteri has been 

 bestowed. 



Do the Ganoids form an integral part of the class of Fishes? Are the 

 distinctions between the Mullerian Ganoids and Teleosteans then of no 

 more than ordinal value ? 



Naturalists will admit that the differences between the natural groups 

 that have been named Teleostei, Elasmobranchii, and Dermopteri, are of 

 much greater value than those which have been employed to separate the 

 Teleostei into the groups that have been called orders. It may be objected 

 to this view that orders are not necessarily of equal value. Such may be 

 admitted to be the case ; orders may be of quite unequal value. But there 

 are between the groups above named, important fundamental differences 

 which can scarcely be considered as of only ordinal value. The distinc- 

 tions between them, as well as the Ganoids, have been even regarded by 

 Agassiz as indicating classical value. While naturalists will not probably, 

 at least immediately, accept this doctrine, it must still be admitted that 

 three of those groups, if not all, are of much more than ordinal importance. 

 For the present, then, they may be regarded as subclasses. 



But it will be doubtless questionable with some whether the Ganoids are 

 entitled to an equal rank with the Elasmobranchii and the Dermopteri : 

 whether they do not themselves belong to one subclass composed of them 

 and the Teleostei, or typical fishes. 



Although the Ganoids do not externally present the same trenchant 

 characters as the Elasmobranchii and Dermopteri ; although there is con- 

 siderable resemblance between representative genera of the Teleostean and 

 Ganoid groups : and though the limits of those groups have been and may 

 perhaps lie still considered doubtful, there are important and permanent 

 anatomical distinctions between them, and those anatomical characters 

 have been regarded as possessing real value. While, therefore, we may 

 admit that there is not as great differences between the Teleostei and the 

 Ganoids, as between the other subclasses, we may still, believing that 

 groups need not be of exactly equal value, regard those two as representing 

 distinct subclasses. At the same time, it is admitted that future researches 

 and moie profound investigations may demonstrate the unity of those 

 subclasses. 



Those researches may also confirm the idea of the absence of homogeneity 

 in the class of Fishes, and prove that three classes are compounded under 

 that name which are equivalent to the subclasses, as here adopted, of the 

 Dermopteri, the Elasmobranchii, and the united Teleostei and Ganoids. 

 The two latter may then be found to form the subclasses of that class.* 



*There is still room for doubt as to the value of the distinctions between the 

 various groups of the cold blooded vertebrated animals. Professor Owen has pro- 



