AFFINITIES OF THE SQUALIN^E. l65 



specimens. This, of course, can only be done by slow 

 degrees, and by different naturalists in various parts of 

 the world : but the spirit which is now abroad, particu- 

 larly among the rising naturalists of our colonies, will 

 do much to hasten this ; and the time will then come, 

 when the groups of the Squalidce will be established on 

 the best of all foundations, — their analogical resem- 

 blances. This digression, although long, may not be 

 thought out of place ; and we shall now proceed, as we 

 intended, to recapitulate the affinities of these two 

 groups, before we enter further upon their analogies. 



(145.) Let us first take the genera of the Squalince, 

 or those sharks which have no temporal spiracles. 

 Commencing with Squalus (improperly named Car- 

 charias by Cuvier*), we find a numerous assemblage 

 composed of Alopias Raf., Cericteus Raf., and many 

 others, imperceptibly leading to Dalatias. Of this 

 latter, Rafinesque expressly says, that although his 

 D. nocturnus has spines on the dorsal, yet that it has 

 no spiracles and no anal fin. It is worthy of remark, 

 also, that he places this genus close to our Squalus ; 

 observing, that it differs from that in having no anal 

 fin, and from Centrina Cuv. {Squalus Raf.), in 

 having " no spiracles." From this we pass to Isurus, 

 Raf., distinguished — as are all fissirostral types, both of 

 birds and beasts — by a very lengthened snout, and a 

 deeply forked, equal tail. Another character, more ge- 

 neral in this genus, is the excessive size of the branchial 

 openings; and both these latter characters are found in 

 Selache and Lamna. But now, having reached the 

 passage to the Centrince, we begin to see the incipient 

 development of the temporal orifices, asserted by Dr. 

 Smith to exist in Lamna, where Cuvier says they are 

 not to be found. Next follows Rineodon Sm. which 



* We say improperly, because, in this instance, and in numerous others, 

 M. Cuvier, while he professes to retain the genus Squalus, virtually abo- 

 lishes it ; since he does notjpreserve the original name to any one of its 

 divisions. 



M 3 



