Echinoderms. 



75 



i) Feather-stars {Crinoidea). Of these there is one species 

 only in the Aquarium: Antedon rosacea (fig. 6) in straw-coloured, 

 orange-coloured, blood-red, or spotted brown and white varieties. 

 Generally they hold on to coral-branches, so as to appear like 

 flowers, growing on submarine trees. 



2) The Starfishes (Asteroidea) are represented in the Aquarium 

 by the genera Luidia (fig. 5), Astropecten (fig. i), Asterias (fig. 3), 

 Echinaster (fig. 2), Palmipes, and others. 



3) The Brittle-stars {Ophuroidea) are also present, but attract 

 the attention of the layman much less. To them belongs, for 

 example, Ophioderma (fig. 4). 



4) The Sea-urchins {Echinoidea), on the other hand, are very 

 conspicuous. The large yellow ovaries (roe) of Strongylocen- 

 trotus and alhed species are eaten in Naples raw as we eat oysters. 

 Sphaerechinus (fig. 8) is of a beautiful violet or reddish-brown 

 colour; and Dorocidaris (fig. 7) is remarkable on account of the 

 size and thickness of its spines, which are few in number, and 

 on which hydroids and banacles sometimes settle. 



5) The Sea-cucumbers {Holothuroidea) are very common in 

 the Bay of Naples, and the Aquarium contains about half a dozen 

 kinds, among which are Cucumaria (fig. 9), mentioned above, 

 the brown Holothuria (fig. 10) and the flat Stichopus (fig. 11). 



Fig. 160. Two Holothurians with Tierasfer. On the left a fish is entering; on the 

 right one has the front part ol its body projecting out. 



