144 THE CILIATED CELLULARIA. 



the opening and closing of it repeatedly. It is a beau- 

 tiful piece of mechanism, contrived for the protection 

 of the delicate little inhabitant, permitting him to 

 inhale the surrounding fluid without exposing himself, 

 and enabling him in a moment to shut and bar his 

 gate on the approach of danger. For I see that it is 

 not necessary that the polype should protrude in order 

 that the door should open widely ; this seems to be 

 dependent on the relaxation of the muscular ligament ; 

 it is often wide open while the animal is far within, 

 then in a moment it is pulled to, with a simultaneous 

 shrinking on the part of the inhabitant, though with- 

 out any appreciable withdrawing further. 



Figs. 10 to 12; lateral views, the door open in dif- 

 ferent degrees. 13, 14 ; back views, door open, and 

 shut. 



Anguinaria spatulata, though described as rare, is 

 by no means uncommon in this neighbourhood. It is 

 very frequently found densely investing the stems and 

 fronds of the smaller sea-weeds that grow at low 

 water. 



THE CILIATED CELLULARIA. 



Still more abundant is another species, like the 

 former frequently parasitic on sea-weeds, but less 

 exclusively so, Cellularia ciliata. 



To the naked eye it appears like a minute shrub 

 composed of numerous branches rising to about half 

 an inch in height. With the microscope the branches 

 are seen to be set with a number of transparent cells, 

 somewhat like a wine glass in form with the rim 

 oblique. They are set alternately on opposite sides 



