88 



Part second. 



lors. He will therefore be a little astonished to find the Sharks of the 

 Aquarium scarcely a yard in length, and will probably look upon them, 

 as either young Sharks or not as genuine ones. We would therefore 

 remark that amongst the many forms of Sharks there are small ones 

 which are however "true Sharks", as both they and the more common 

 Dog-fish agree in their characteristics with the larger species. A com- 

 parison of the Rock Dog-fish (Fig. 174), with the Bass (Fig. 175), a 

 bony fish, will quickly reveal these essential features. 



Fig. 174. Scyttium catulus, 

 Vfi nat. size. 



Fig. 175. Labrax lupus, 

 G nat. size. 



The Bass is covered over its whole body with silvery fish -scales, 

 has its mouth at the anterior extremity, two large moveable gill-covers, 

 staring eyes not provided with lids, and nasal apertures distinct from the 

 mouth. The body of the Shark on the other hand is not covered with 

 scales, but with bony spines, which cause the skin to feel rough. The 

 mouth is on the under side of the head in the form of a transverse 



