58 P^J't second. 



coloured pieces 400 — 500 frs. and even more, but the pieces vary- 

 greatly with the fashions. 



In the Bay of Naples also, some rocks arise out of the muddy 

 bottom about half-way between Naples and Capri on which the 

 Red Coral grows. From there the fishermen of Santa Lucia take 

 every 3 — 5 years 100 — 200 kilogrammes each, and thence come 

 also the examples in tank 21. Usually, however, these do not live 

 long, as they are mostly fished in the summer and cannot with- 

 stand the great difference between the Aquarium temperature at 

 this time of year and that of the sea-bottom. If they are taken 

 in autumn they remain alive for half a year or more. A preserved 

 piece is to be found in a small glass on the floor of the tank. 



Medusae or Jelly-Fish. 



Those who come from northern seas and remember to have 

 found on the sands ugly and offensive masses of jelly, will find 

 it difficult to associate with these the large Rhizostoma (fig. 8^) 

 and Cotylorhiza (fig. 84), or with the smaller Pelagia (fig. 80), 

 Tima (fig. 82), Olindias (fig. 81), Carmarina (fig. 79) etc., which 

 he sees here swimming around; yet those lumps were nothing 

 more than the corpses of similar animals. The Medusae change 

 in appearance after death much more rapidly than most other 

 animals because they consist chiefly of water (95 — 98%). Their 

 almost complete transparency, the beauty of their movements, 

 and their often brillant colouring, make them very attractive 

 objects. As they swim, they take the form of a mushroom or 

 an open umbrella, the regular opening and closing of the umbrella 

 driving them along. From the centre of the bell hangs a long, 

 generally hollow, gelatinous stalk, also transparent; it is provided 

 at the end with an aperture, the mouth. In some jelly-fish, how- 

 ever, such as Cotylorhiza and Rhizostoma the stalk is shorter and 

 divided into a number of small lappets, each of which bears a 

 mouth leading into a common cavity, the stomach. From the edge 

 of the umbrella hang down long tentacles, which the animal can 

 contract at will or elongate to a considerable extent. These ten- 

 tacles are provided with numerous stinging-cells, such as have 

 been described in the case of the Actiniae (see p. 63); and, as there, 

 they afford an efficient means of defence for the delicate body. 

 The unpleasant stings occasionally experienced in sea-bathing are 

 generally due to contact with these jelly-fish. Some species, 

 indeed, which attain a size of one to two feet and a weight of 50 to 

 60 pounds, can sting very seriously. 



A few species shine at night with a greenish light ; thus Pelagia 

 has received the specific name of noctiluca. 



