- 61 - ; ';/. 



pon of offence and defence, the fish killing or at least paralys- 

 ing its smaller prey by its means. 



The electric ray bears living young, sometimes eight to four- 

 teen at one time. It is one of the commonest fish in the Gulf, 

 and, in spite of its bad flesh, is often found in the market. It 

 lives very well in confinement and there is always in the Aqua- 

 rium at least one fish placed in a small open tank for visitors 

 to experiment with. 



Many other kinds of rays live in the tanks of the Aquarium; 

 for example, the Raja, and the thorny-ray (Trygon), but the 

 last is rare. The first have a rhombic body of a brown colour, 

 and a thin prickly tail. The Trygon is violet-black in colour 

 with a wing like extension of the skin and long thin tail. On 

 this tail there is a spike said to produce dangerous wounds. 



We must still mention, while speaking of fishes, the remark- 

 able lancet- fish (Amphioxus lanceolatus), which has been 

 so much talked about of late years , and which is considered 

 to be the smallest and simplest form of vertebrates. This little 

 fish scarcely two inches long, and almost transparent, has no 

 fins, no bones, and no brain. Instead of a heart it has only some 

 pulsating vessels filled with colourless blood, and in its remain- 

 ing organic system , shows such a primitive formation , that 

 the species has been separated from true fish and placed in a 

 peculiar subdivision (tube-hearts, skull-less fish). But far more 

 on account of its manner of development than on account of 

 its bodily construction, this animal has attracted the attention 

 of zoologists, for the first stages of that development have the 

 greatest resemblance to those of the Ascidians. The Amphio- 

 xus is therefore considered to come next to the original form 

 of the vertebrate animals. Another theory sees in its low or- 

 ganisation the result of a retrograde development, and points 

 to its habits , for it leads a light-shunning existence in the 

 shallows of sandy coasts, and rather resembles a mud-inhabiti- 

 ting worm than a fish. It is found by thousands in sandy 

 places on the shores of Posillipo and similar localities on the 

 Gulf, and has also been proved to exist in the German Sea and 

 the Ocean (South- America). It can only be kept in the Aqua- 

 rium wben provided with a 'quantity of sand in which to bury 

 itself, and it only issues forth at night or when disturbed. 



Besides the fishes, we have one reptile in the Aquarium , 

 the Couana (Thalassochelys corticata), a Mediterranean 



