^g Part second. 



gusting animal, the hooked spines of which penetrate into the 

 hand that touches them, and cause inflammation. Alciopa (fig.i6i) 

 is as transparent as the jelly-fish and other pelagic animals, and 

 like them lives near the surface of 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. 58). 



Polyzoa or Bryozoa. 



The name Polyzoa, i. e. multiple animals, was given to this 

 group from the fact that they live in large colonies, like corals. 

 By the German school they are always called Bryozoa or moss- 

 animals; a name which arose from the moss-like or coral-like 

 growth which these colonies form. 



The graceful net-like frill of Retepora (fig. 115), or the branch- 

 ing stem of Myriozoum (fig. 116), may easily be mistaken for 

 corals, to which, however, they are by no means allied. Careful 

 investigation has shown that the little animals which form these 

 growths, and live together in colonies, are very different from, 

 and more highly organized than, the polypes of a coral. 



The Polyzoa are widely distributed in all seas, and present a 

 wonderful variety of form. A kind very common on the British 

 coast and well known to all visitors to the sea-side is the leaf-like 

 growth of Flustra, the sea-mat, the colour and texture of brownish 

 white paper. 



Crabs, Lobsters, Shrimps, Barnacles, etc. (Crustacea). 



In the great family of the Crustaceans the reader has at least 

 one old friend, namely the lobster. We will make use of this ani- 

 mal, then, as an introduction to the other members of the class, 

 which although sharply divided off from other divisions of the 

 animal kingdom has within itself many diverse forms. The friend 

 just mentioned belongs to the most highly organized group, to 

 the ten-legged crustaceans, or Decapods, and to the long-tailed 

 (Macrura) division of them. 



The Lobster, Homarus vulgaris (fig. 44), is, on the whole, an 

 enlarged copy of the fresh-water crayfish; and visitors will easily 

 recognize, from examining the large specimens in the Aquarium 

 (tank Nr. 6), what are the principal features of its organisation. 

 The body is divided into an anterior part, consisting of head and 

 chest, which is really jointed but covered on the upper surface 

 by an unjointed shell (carapace); and a posterior part, composed 

 of a number of rings forming the "tail" of the Lobster, which 

 terminates in a fin composed of broad, flat plates. The anterior 

 portion bears the stalked eyes and two pairs of antennae or feelers, 

 one pair very long, the other short and forked. Behind these, 



