ZYGANINJE, OR HAMMER-HEADED SHARKS. 



133 



tina contain very few species ; and they are so much 

 isolated^ when compared with the graduating links of 

 connection seen among the true sharks^ that their pre- 

 cise situation in the circle is still open to dispute. We 

 have to regret, also, the same paucity of forms between 

 these aberrant Squalidce and the three aberrant families, 

 or rather types of families, already noticed; so that, 

 whether the true sharks (^Squalidce) are directly con- 

 nected to Chimcera, or to Polyodon, is a question 

 impossible to be determined at present by simple ana- 

 lysis. It might, indeed, be thought, on a hasty view of 

 the subject, that Pristis leads immediately to Polyodon: 

 but all authors agree, and we think justly, that this sin- 

 gular fish connects the sharks to the rays ; and this will 

 be apparent when we come to describe it. Squatina, 

 also, has more the aspect of a ray than of a shark. Zy- 

 gcence, therefore, is that group of the Squalidce most 

 removed from the RaidcB; and it must, consequently, 

 stand at the furthest extremity of its own family, — in 

 other words, at that point which is in the line of pas- 

 sage to Polyodon. With this group, therefore, we shall 

 now commence our survey. 



(117.) The ZyganincB, or 

 hammer-headed sharks (fig. 

 10. a) present, at the first 

 glance, a marked and decided 

 character in the form of the 

 head, which, as their name 

 implies, may be compared to 

 a hammer, the body of the 

 fish representing the handle; 

 in other words, the head is 

 flattened, with the sides so 

 much prolonged that the 

 eyes, which are at the ex- 

 tremities, appear placed on 

 two great peduncles. Cu- 

 vier remarks that the ani- 

 mal kingdom presents no 

 K 3 



