134 CLASSIFICATION OF FISHES. 



Other example of a head so formed ; but this is incor- 

 rect : the genus Diop-sis (b) among insects, gives us a 

 perfect representation of these hammer-headed sharks : 

 the resemblance, in shorty is so striking, as alternately to 

 excite our wonder and our risibility at seeing a fly so like 

 a fish (Jig- 10.) In other respects, we find the structure 

 in general accordance with the rest of the true sharks. 

 There are no temporal spiracles ; but the teeth are 

 strong and acute, crenated on their edges, and placed in 

 three rows. The female is oviviparous. The species 

 are few, and these not well understood. The Z. mal- 

 leus is that which is best known : it inhabits the seas of 

 Southern Europe, and grows to twelve feet long. A second 

 is found in India : and what seems a third is peculiar 

 to the Austrahan seas. The most typical species, how- 

 ever, yet known, has been recently discovered and de- 

 scribed by Dr. Cantor* as the Z. laticeps {fig. 11^). These 



are aU typical examples ; but the aberrant forms, which 

 have the head more heart-shaped, it will be necessary to 

 place in a distinct genus. 



(118.) The second type of the aberrant sub-families 

 is the genus Pristis, or saw-fish. This genus has 

 been placed by all writers between the sharks and 

 the rays ; and with great truth, for it partakes almost 

 equally of the structure of both — uniting, however, a 

 peculiarity altogether its own. This consists in the 



* An acute and most zealous naturalist, whose materials for elucidating 

 the fish, serpents, and mollusca of India are particularly valuable; the 

 drawings and descriptions having been made from the living subjects. 



