CAKTILACHNOTJS SKELETON OF THE SKATE. 



641 



foot of higher animals, is appended; and likewise in the male it gives 

 attachment to additional organs called daspers, the use of which will be 

 explained in another place. 



Fig. 316. 



Cartilaginous skeleton of the Skate. 



(1745.) The anterior portion 

 of the spine in the Skate is not 

 as yet divided into distinct pieces; 

 and even in the posterior part, 

 the number of vertebral arches 

 is twice as great as that of the 

 separate bodies of the vertebrae. 



(1746.) In all the Chondro- 

 pterygii the ribs are mere rudi- 

 ments, and in some cases can 

 scarcely be said to exist at all. 



(1747.) The Sturgeons (Stwri- 

 onidce) form a kind of connecting 

 link between the osseous and car- 



tilaginous fishes ; and in them a 

 large swimming-bladder exists, 

 from which is obtained the valu- 

 able material called isinglass : 

 but in the Sharks and Rays this 

 organ is not found ; consequently, 

 especially in the tribe last men- 

 tioned, it is only by means of the 

 vigorous flappings of their enor- 

 mous hands that these ground- 

 fishes are able to raise them- 

 selves from the bottom. The dis- 

 position and relative importance 

 of different parts of the muscular 



