Tin: sua res. 



14. r . 



Order 1. Plagiostomi. — Our most common shark is the 

 mackerel Bhark (Isurus ptmctatus, Fig. L86 [I 3 from 

 four to eight feel in length, ami is often taken in fish-i 

 being a surface-swimmer. In the thresher shark 

 vulpes), the upper lobe of the tail is nearl} as long as the 

 body of the shark itself, [t or fifi et in 



leugth, and lives on the high si \\. • 



Nearly twice in. if tin.' thresher is the great bask 



shark, v ixima, of the North Atlantic, which 



comes nine to thirteen metres (thirty <>r fori ) in 



length. It has very large gill-slits, and is by no meai 



- mosl sharks, since it lives on small fishes, and 



K 



CW*^ 



»'j- — ■ 



\\ 



]':■■ 1-. rias. From Ltitken's Z> 



in part, probably, on -mall floating animals, straining them 

 into its throat through a of ray- or fringes <>f an 1 



tic hard substance, but brittle when bent ton much, and 

 arranged like a comb along the gill-openings, thi 

 beii -mall. 



Among the smaller sharks is the dog-fish (Squal - . I 

 canus), distinguished by the sharp spine in front of 1 

 of the two dorsal I'm-. It i< caught 111 great numl 

 the ml which is extracted from its 1 The dog-shark 



stelus canis), which is a In :1c larger than ti sj-fish, 



■ mini;- ov< r a metre (four feet) long, bi 1 its 



young alive. 



The hammer-headed shark is so 1 lied from the head 

 projecting far out on each side, tic • ated in 



the end of each projection. 



