ACTI^^OZOA. 



211 



oceanic, and described by such names as " Pol3rpes 

 nageurs." It is more probable, however, that, 

 under ordinary circumstances, these creatures live 

 with their proximal extremity plunged firmly into 

 the sand or mud of the sea-bottom ; the distal 



Fig. 37. 



PennatulidjE and Gorgonidje : — a, dried stem of Virgularia 

 mirabilis ; b, portion of another stem, in the living condition ; c, 

 corallum of Mopsca costata ; d, fragment of the same, (a is 

 reduced one-third ; b and c are of the natural size ; d is magni- 

 fied.) 



end of the coenosarc, which bears the numerous 

 polypes, freely exposing itself to the influence of 

 the clearer water above. 



The coenosarc of the Pennatulidce may be 

 slender and simply elongate, with very short 



p 2 



