THE SHARKS AND RAYS. 419 



toothless mouth beneath the snout, the single gill-opening, 

 bony plates or shields on the head, and cartilaginous 

 skeleton. The breathing-spiracle is present, as in sharks. 

 The sturgeon is only a wanderer to British rivers, the 

 Thames and Severn among them, which it doubtless enters 

 for the purpose of depositing its spawn. Examples of over 

 lo feet in length and 500 lbs. weight have been taken in 

 British waters. In colour, this fish is reddish or bluish 

 grey along the back and sides, white beneath. It spawns 

 early in the year. The food of our Sturgeon consists of 

 mud and of the worms and molluscs contained in it. The 

 flesh has a faint pink tinge, and there is a good deal of 

 fat. It is not bad eating, but rather coarse, and rarely 

 fetches anything more than a very low price in the 

 market. Enormous shoals of sturgeon make their way 

 up Russian rivers from the Caspian, their most valuable 

 products being the roe, which is made into caviare, and 

 the air-bladder, which makes isinglass of the first quality. 

 In this country it is a royal fish, belonging to the Crown. 



CHAPTER XXYI. THE SHARKS AND RAYS. 



British seas contain representatives of five out of the 

 nine existing families of sharks, some of formidable dimen- 

 sions, others of mischievous habits, the latter being in our 

 waters of small size and comparatively harmless. It seems 

 probable, indeed, that the vermin will increase in these 

 parts, a result contributed to by the cutting of the Suez 

 Canal and the rapid growth of our seaport towns; for 

 nothing is so likely to attract sharks in from the ocean as 

 the presence of more off'al and sewage in the shallower 

 water, as an example of which we have the enormous 

 increase of sharks in Sydney Harbour during the past 



