CCELENTERA TES 



3ii 



the bell of three-eighths of an inch, which has four long tentacles on the margin 

 set at equal distances. 



Representing the Siphonophora we have the sailing jelly-fish (Velella) with a 

 flat disc-shaped body, on the upper side of which is an upright crest, acting 

 as a sail, and on the under side a large polyp, surrounded by circles of smaller 

 ones, those near the edge having tentacles. One of the best known species is 

 V. spirans, often met with far from land, driven along by the wind actincr on the 

 sail-like crest. 



Of the Scyphomedusse a common repre- 

 sentative is Aurelia aurita of the European 

 seas, which often appears in swarms, and is 

 well known on the shores of 

 the North Sea and the Baltic. 

 In colour it is 

 blue, but another 

 common species, 

 Cyanea capillata, 

 is yellowish 

 brown, or yellow, 

 and sometimes a 

 yard wide, the 

 filamentary ten- 

 tacles being over 

 2 yards in length. 

 A third species 

 (C. arctica) is 

 the largest of all known 

 jelly-fish, its disc exceeding 

 6 feet in diameter and its 

 filaments extending for 120 

 feet or more. To the same 

 group belongs the Mediter- 

 ranean Cotylorhiza tuber- 

 culata, which has tentacles 

 in the shape of long 

 suckers, the prevailing colour being yellowish often spotted with white on the 

 disc, amber on the arms, and violet or blue on the suckers. Another curious 

 form also frequent in the Mediterranean is Charybdea marsupialis, one of the 

 Conomedusae with well-developed eyes. 



In the stationary group the best known is Lucemaria quadricornis, which 

 measures nearly 3 inches across and is greyish or yellowish brown in colour, and 

 generally found on red seaweed in the North Atlantic, the North Sea, and the 

 Baltic. It connects the free jelly-fish with the anemones and corals. 



The sea-anemones and corals belong entirely to the sea, and reach their greatest 

 development and variety of form in the warmer waters, where they are generally 

 attached to rocks or other substances, including the shells of living crustaceans. 



ACTINIA EQUINA. 



