Annelids. 67 



In the sea we may often see a natural g-arden of this kind; looked 

 at through the clear Avater of a rocky coast it is an enchanting sight , 

 and always yields a rich harvest to the naturalist , not only of these 

 worms, but of many other animals which have taken up their abode 

 amons'st them. — The tube is merelv a house formed bv the worm, and 

 does not adhere to its body. But not all Tube-worms secrete cal- 

 careous shells or leathery ones, like those mentioned above; some saturate 

 the sand in wliich they burrow with a slimy secretion from their skin and 

 form in this way delicate tubes of sand. Such are possessed by Are- 

 nieola, the lug-worm, so much used as bait in England. In the same 

 manner Terebella forms a dwelling, and its orang-e-coloured tentacles 

 may be seen protriiding- from the sand at the bottom of the tank, twist- 

 ing- about in all directions in search of food. Others cement together 

 small stones, shells, and other similar objects (Shell-binders); while some 

 encase themselves with mud , or form long horny tubes open at both 

 ends and resembling- the shaft of a feather: Onuphis. This latter group 

 crawl about freely like the grub of tlie Caddisliy, while the « palm-trees » 

 of tank 22 fix themselves to rocks , Avoodwork , or otiier large objects , 

 or simply bury the lower end of their tube in the sand. Some kinds are 

 a veritable plague to navigation, accumulating in such masses on the keels 

 of ships that they retard their progress. 



All these animals, when young, are entirely differently constituted. 

 From the eggs issue free-swimming larvie of very curious form, wliich 

 after a while fix themselves to stones or weeds, and then by a complete 

 metamorphosis change into the worm-like animal and encase themselves 

 with a tube. 



Besides these tube-inhabiting Annelids, of wliich all tlie warmer seas 

 possess a variety of beautifully coloured kinds, there is a second group, 

 no less rich and varied: the f r e e - 1 i v i n g Annelids. 



The Bay of Naples has long been celebrated among zoologists as 

 one of richest localities for these worms, and already up to the present 

 date (including the tube-inhabiting worms) about ;}U0 different species 

 have been described. Still only a small portion 

 are suitable for the purposes of an Aquarium, 

 as most of them live secluded in the mud or 

 in the cracks of the rocks. One of the finest 

 is the Sea-mouse, Aphrodite (Fig. 123), the 

 bristling coat of whicii reflects with a bright 

 metallic lustre all the colours of the rainbow. 



Its nearest relation' is the verv common 



Hermione, wliich in spite of its beautiful name ^ "^f^^f 



is a disgusting animal , the hooked spines of ^^-^■^* "^^ '*^ 



'€^ 



which penetrate into the iiaud that touches them, "^h^j^^i^' 



and cause inflannnation. Aleiopa (Fig. 162) is mT^ 



as transparent as the jelly-fish and other pelagic pj^ ,g2 ^^^.^^^ Cantrainii, 



animals, and like them lives near the surface of '/a "at. size. 



the sea. It is rarely seen in the Aquarium 



(Tank Nr. 20), since the capture of such animals, as already mentioned, 



depends much upon the weather (see p. 62, foot-note). 



