222 



VERTEBRATE ANIMALS. 



and is distinguished by the following characters : The skull 

 and lower jaw are well developed, but the skull is not com- 



Fio. 108. Cephalaspia LyelUi, from the Old Bed Sandstone of Scotland. 



posed of distinct bones, and simply forms a kind of cartila- 

 ginous box. The vertebral column is sometimes cartilaginous, 

 sometimes composed of distinct vertebrae. The integument- 

 ary skeleton is in the form of placoid scales (Fig. 100, c) 



FIG. 109. Elasmobranchii. 



A. White Shark (Carcharias). 

 (Chimwrd). 



B. King of the Herrings 



