178 THE ANIMAL KINGDOM. 



observe ; for the cells are not so unlike those of the common- 

 Sertularia pumila (the upper part of the cells bend out- 

 wards and downwards slightly), but the vesicles are most 

 unlike. You see they are pear-shaped, wrinkled, cleft at 

 the top, and more silvery in hue. This coralline grows on 

 shells in deep water, and is parasitic on other zoophytes, 

 small white clusters being often found on Plumularia, 

 falcata and Sertularia argentea. 



LAOMEDEA GENICULATA, 



the Knotted-thread Coralline a very common and beau- 

 tiful zoophyte, one of the family of Campanularidse, and 

 worthy of minute examination. In this species we are 

 successful in preserving the polypes themselves inside 

 those tiny cups. The fibres are twisted in a network 

 on the sea-weed usually a frond of Laminaria or Fucus, 

 and slender threads bristle thickly from the stem a zigzag 

 line, on each side of which rise winged stalks bearing the 

 polype cell; here and there are large vesicles containing 

 Medusoides. The peculiar interest of these Laomedea 

 is the wonderful adaptation of their structure to the 

 element in which they live. How would this fragile cup 

 and slender stem resist the wild storms of the ocean if it 

 had not been provided with that jointed pedicle, which bends 

 to and fro on every side in ease and safety, whilst the little 

 inhabitant stretches forth its single row of tentacles, and 

 draws food into its probosciform mouth ? The vesicles also, 

 though apparently sessile, are fixed upon a footstalk like a 

 screw, which enables them to resist the shocks of a stormy 

 sea. 



LAOMEDEA DICHOTOMA. 



Laomedea dicJiotoma, or Sea-thread Coralline, is found in 

 long, filiform, zigzag branches, on old shells or stones, or 

 sea-weed, within tide-mark. 



PLUMULAEIA CEISTATA. 



Observe this both with reflected and transmitted light. 

 It is the Feather Coralline picked up as sea-weed by chil- 



