FISHES. 227 



CHAPTER VIII. 



FISHES. 



IN the same way that most Mammals are restricted in their 

 habitat by their inability to travel except by land, Fishes 

 are restricted to living and travelling in the water. The 

 number of kinds found in Fresh water is very limited ; by far 

 the larger number of known forms being Marine. The most 

 interesting point in the natural history of these animals is in 

 connection with their breeding habits. Several of the species 

 recorded in the following pages are generally regarded as 

 marine fish, and it will probably surprise many to find that 

 the Flounder, Shad, and Sturgeon have ever ascended the 

 Severn as far as Shrewsbury ; although it is well known that 

 the Salmon comes up to spawn. These fish reside, more or 

 less, in the sea, but ascend rivers to deposit their eggs in 

 fresh water ; they usually return to the sea soon afterwards. 

 The young after reaching a certain size, also go down to salt 

 water. This is so with most migratory fish, but in the case 

 of the Eel, the rule is reversed ; it spends most of its life in 

 Fresh water, and when adult goes down to the Salt water, 

 and after depositing its spawn in the deep sea, disappears. 

 The characteristics of fishes are so well-known that it is only 

 necessary to briefly allude to them. They are covered with 

 scales which are appendages of the epidermis. [Sometimes 

 these are deeply embedded as in the Tench and Eel, or take 

 the form of plates as in the Sturgeon and Stickleback.] 

 The limbs are modified into the form of fins, which guide 



