l62 CLASSIFICATION OF FISHES. 



their internal analogies. Some of the more recently cha- 

 racterised forms we have not personally examined^ and 

 others are not now before us, so that we had almost de- 

 termined not to have prosecuted our analogical views 

 further than to the sub-families : but this might have 

 given an impression to some few of our naturahsts, that 

 the theory could not be carried further^ and that we de- 

 serted our former declaration^ that every group, whether 

 large or small, if natural^ would contain representations 

 of all others. To show, therefore,, that^ even in our 

 present dilemma^ there is some ground for this asser- 

 tion — so fully demonstrated already in the class of 

 birds — we shall make the attempt. If one or two of 

 these analogies carry with them an appearance of truth, 

 our principle, substantially, is gained ; while, for the 

 rest, if we are in error, these very errors will serve as 

 land-marks to others, and elicit that additional inform- 

 ation which is absolutely essential before we can hope to 

 work out the internal affinities and analogies of the great 

 number of forms comprised in the sub-families Squalince 

 and CentriiKB. 



Analogies of the Squalin^e and the Centrin/e. 



Genera of the -r.-, .<■ j ? • ? Genera of the 



Squa.i>^ ,' ^"""^S^,^",!;;^''^^^^"' Centring ; 



no spiracles. unuacce?!,. with spiracles. 



Squahis Linn. Typical of their respective groups. Centrhia Cmv. 

 Balatias Raf. Spines to the dorsal ; no ventral fin. Galeus Raf. 



/v7/»-;/(f Raf f ^"O"*^ °^ muzzle excessively long, 7 c„,;/,-„,„ r„v 



l>,urus K&i. ^ projecting beyond the mouth. ^!icijum7n (.uv. 



T.- J c -^1 f Mouth at the end of the muzzle :> y-,^,.„„._ /-,.,„ 

 Rineodon Smith \ ^ vertical i ^^^^^^f^^^ Cuv. 



fThe second dorsal fin opposite the") 

 I anal : the two last branchial ( 

 Scoliodon M. H. ^ openings placed above the pecto- yMustelus Cuv. 



teeth the same in both 1 



^ openings 

 I ral fin : 

 L jaws. 



(144.) It will tend much to elucidate the above table^ 

 if we first of all briefly recapitulate the reasons that have 

 induced us to arrange these two series in the order in 

 which they now stand; so that, before entering on an 

 explanation of the analogies they bear to each other, we 

 shall take a hasty glance at the affinities of the genera 



