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TRANSACTIONS UYKRPOOL BIOLOGICAL SOCIETY. 



common star-fish, there are usually to be seen in our tanks 

 the Sun-star, Solaster papposus, with twelve to fifteen 

 rather short rays radiating from a large circular disc, the 

 brilliant red cushion-star Porania pulvillus, the flat 

 pentagonal Palmipes placenta, and the pale strawberry 

 Stichaster roseus, with a relatively small disc and long, 

 gradually tapering rays. The three last named are 

 obtainable only in deep water. Star-fishes are voracious 

 animals, and often do harm to the fisheries, bivalve 

 molluscs such as the oyster, the mussel, and the scallop 

 being their favourite food. 



"v^// I I !\ }\ v ~- N ^ 



tsUrinaglbl rubeiu, 8 Ophiothrix fraoilis, 4 Cueu tntut. 



Fig. VI 1 1., Eohinodermata (natural size.) 



I Mmitprids, the sand-stars and brittle-stars, have long 

 snake-like arms, sharply marked off from the disc, and 

 have do suckers on their tube-feet. They have an 

 interesting method of locomotion peculiar to themselves; 

 instead of gliding along smoothly as the star-fishes do, 

 they jerk fheir bodies along by alternately curving and 



