504 



PISCES FISHES. 



which, the palatine, performs the office of an upper jaw and 

 supports the teeth, while the other connects the lower jaw with 



the cranium. The lower jaw 

 itself, moreover, consists of 

 but one piece on each side, 

 to which the teeth are at- 

 tached. 



From the peculiar con- 

 formation of the respiratory 

 apparatus, which will be ex- 

 plained hereafter, there is no 

 occasion for any opercular 

 flap ; this, therefore, is not 

 present : nevertheless, the hy- 

 oid and branchial arches re- 



semble pretty much those of 

 osseous fishes; only the latter 

 are situated further back- 

 wards, being placed quite be- 

 hind the skull, under the 

 commencement of the spine. 



The bones of the shoulder 

 are represented by a strong 

 cartilaginous zone, which in 

 Sharks is quite unconnected 

 with the vertebral column, 

 but in the Skates (Raia) it 

 is fixed to two large lateral 



