SQUALIN^. SCOLIODON. SQUALUS. 139 



Zygana. We are led to believe that ScoUodon is a 

 generic, and not a sub-generic^ type, from its containing 

 five species; but as no typical example has been naraed^ 

 and no notice taken of the form of the head and tail 

 (characters^ in our opinion^ of much greater importance 

 than slight variations in the teeth), our idea of its rank 

 is entirely conjectural. If Rafinesque's Tetroras, on 

 the other hand_, has only four spiracles, it may fill the 

 place here assigned to ScoUodon; which, according to 

 Muller and Henle*, diff^ers only from the true sharks in 

 the next genus, by such slight modifications in the teeth^ 

 that, in the absence of further characters, we hardly 

 venture to incorporate it in our present survey. The 

 genera Triaenodon and Leptocharias, each with only one 

 example, appear to us — judging from the characters 

 that have been as yet assigned to them t — no other 

 than aberrant species ; but this, again, is mere conjec- 

 ture. It is clear, however, that they all enter into the 

 present sub-family, as they are destitute of temporal 

 spiracles. 



(122.) The next is the typical genus of the whole 

 family; and as such we retain to it the original generic 

 name [j; of Squalus, in preference to that of Car char ias 

 proposed for it by Rafinesque, seven years before 

 M. Cuvier. Here we meet with the most ferocious and 

 gigantic monsters of the whole family ; among these is 

 the great white shark, Squalus carcharias, which some- 

 times grows to the length of twenty-five feet, and which 

 is a savage and destructive wanderer over the whole 

 ocean. Its jaws are armed with innumerable cutting 

 teeth, acutely pointed at their tips, and generally den- 

 tated on their margins, the base being very wide and 



* Mag. of N. Hist. No. xiii. p. 35. — " Differs only from Carcharias Cuv. 

 by the teeth being of the same shape in the upper and lower jaw ; 'viz. the 

 points directed towards the corner of the mouth, with a smooth edge, and 

 a truncated protuberance, either smooth or indented, on the exterior side 

 of the base (5 sp.). " 



t lb. p. 36. 



I The propriety of retaining the original name of a genus to the typical 

 group, has been so well advocated by others, that any further observations 

 of ours would be superfluous. 



