J02 TzTt second. 



a throat perforated with many gill-slits. But its development 

 is even of greater interest to zoologists than its anatomy; for it 

 resembles greatly that of the Ascidians (cf. p. loo) and points to 

 a near relationship of these two groups. From common ancestors 

 the fishes, amphibians, reptiles, birds and mammals have risen 

 to become more and more highly organized while regressive de- 

 velopment has given the Amphioxus, hardly to be recognized as 

 a vertebrate and the Ascidians which have degenerated to a plant- 

 like mode of life. 



Amphioxus lives in the sand of flat coasts and resembles 

 worm more than a fish. It is found in thousands along the beach 

 of Posilipo and similar tracts of the Bay of Naples, where its 

 presence is recognized by a strong smell of iodoform. It was first 

 found on the British coasts by Mr. Couch in 183 1; within the 

 last few years several kinds of Lancelets have been found in other 

 seas. 



In the Aquarium it can only be kept, if a plentiful supply of 

 sand be in the tank (the little open one in front of tank Nr. 10). 

 In this it burrows immediately and only comes out at night or 

 if disturbed. 



Fishes (Pisces). 



And when the reader reaches this chapter about beasts he 

 knows so well, he will either shut the book to — quel giorno piu 

 non vi legemmo avanti — or perhaps he will be glad to be among 

 old friends once more, and will read on to see if he can find out 

 something more about them. We only hope he will find the second 

 plan worth while. 



Anatomists classify fishes into cartilaginous and bony, bio- 

 logists into ground-livers and free-swimmers and gourmands into 

 edible and non-edible. We will consider all three points of view, 

 and will commence with the cartilaginous fishes. 



The cartilaginous fish, or at least those which find their way 

 into the Aquarium, are mostly bottom fish and mostly not eatable; 

 but on the other hand the larger kinds are said to be often very 

 palatable. To the cartilaginous fishes belong the Sharks and 

 Dog-fish and the Skates. 



The word Shark will cause the reader to think at once of those 

 gigantic robbers of the ocean, which have become the terror 

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

 Sharks of the x\quarium scarcely a yard in length, and will prob- 

 ably look upon them as either young Sharks or not as genuine 

 ones. We would therefore remark that amongst the many kinds 

 of Sharks there are small ones which are nevertheless "true Sharks", 

 as both they and the more common Dog-fish agree in their charac- 

 teristics with the larger species. 



