ANALOGIES OF THE CARTILAGINES. * 149 



where the muzzle is pointed, as in Lamna, while the 

 branchial apertures, equally large, amount to seven : the 

 caudal tin, in both, is oblique and unequal. 



(ISO.) We may here close our enumeration of the 

 most prominent variations in this extensive family ; 

 and we shall now take a retrospective view of the 

 whole. It has been our endeavour, with the imper- 

 fect and often contradictory materials before us, to 

 trace, in some degree, the real line of continuity, and 

 the manner in which the different forms blend into 

 each other. Some of these affinities are much more 

 obvious than others ; but as even these latter require to 

 be tested by the theory of analogy, we must now turn to 

 this sort of relationship as essentially necessary to give 

 some degree of verisimilitude to our arrangement of the 

 Squalidce, no less than that of the whole order. We 

 shall, in the first place, arrange the orders of fishes in one 

 column, and the families of the Cartilagines in another, 

 and then see how far the contents of each are analogous 

 in their most prominent characters. 



^T^oi^s. *«"*«■ <***■ of Fishes. 



Raidse. Back armed with spines. " Acanthopteryges. 



Squalidce. Back with soft fins. Malacopteryges. 



Polyodonidce. Pre-eminently cartilaginous. Cartilagines. 



Sturionidce. Body mailed ; mouth very small. Plectognathes. 



Chimceridce. Tail excessively lengthened. Apodal. 



(131.) Before the naturalist enters upon the investiga^ 

 tion of these comparisons, we beg to remind him of one 

 important consideration, that must always be borne in 

 mind in all investigations of this nature, namely, that we 

 are to look only to the pre-eminently typical characters 

 of each group, and not to the exceptions which always, 

 and inevitably, occur in those which are aberrant. It 

 is no more meant, for instance, that all the rays are 

 armed with stings, than that all the Acanthopteryges have 

 spined dorsals : here the absence of spines is the excep- 

 tion to the general character, just as their presence is the 

 exception among the Squalidce and the Malacopteryges, 



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