132 CLASSIFICATION OF FISHES. 



is absolutely disproved^ we see no reason for consider- 

 ing them as purely imaginary. Professor Rafinesque 

 resided five years in Sicily, and therefore had far better 

 means of discovering its rarer productions than na- 

 turalists who have merely staid there for a few months. 

 Some of these genera^ we have no scruple, therefore, of 

 adopting, while others may be held in abeyance until 

 they are verified by further observation. 



(116.) If we look to the different genera in which 

 authors have divided this family, with a view to deter- 

 mine those which are more typical, and such as are 

 aberrant, we shall have but little hesitation in fixing 

 upon Pristis and Zygcena as forming two of these; 

 while most authors agree in bringing Squatina also 

 into the family : this is in accordance, also, with the 

 views of Cuvier, who has separated the hammer-headed 

 group from all the other sharks, and placed Pristis and 

 Squatina in the same rank. There yet remains, how- 

 ever, the great bulk of the family under his genus 

 Squalus: these are obviously the most typical sharks, 

 and, like all such assemblages, contain two distinct 

 groups or sub-families, which we shall here term the 

 Squalince and the CentriiKs; the first being distinguished 

 by the absence, and the last by the presence, of spi- 

 racles. These are small temporal orifices, which, when 

 they exist, are placed immediately behind the eye : their 

 peculiar use is not clearly known, but they must un- 

 questionably perform an important office in the economy 

 of these fishes; because, from their universality in one 

 of these typical groups, and their absence in the other, 

 it would seem that nature intended thus to distinguish 

 them. The two aberrant genera of Pristis and Squa. 



in Sicily, with only three apertures, which Rafinesque has supposed to be 

 the squatina of Linnsus, and so described it. Now I think that the ex- 

 istance of such a species is just as probable, if not more so, as that Rafi- 

 nesque has overlooked two of the spiracles. I can bear testimony to the 

 peculiar tact and unwearied zeal of our author, in detecting species closely 

 allied to each other. I must here again repeat, and the proofs will follow, 

 tha.t not one half of the Sicilian fishes, described by Rafinesque, were known 

 to M. Cuvier, who has not only omitted them in his great work, but thrown 

 discredit on their very existence. 



