30 ZOOPHYTES. 



ment alike numerous. This animal is likewise among the larger species, 

 being about a line and a half in height, and the tentaeula composing its 

 bell expanding nearly as much. Its form is elegant, light, and beautiful. 

 Tt rises very leisurely and gradually from the cell ; but its retreat is most 

 precipitate, vanishing in a moment ; and thus is the cloud composed of 

 multitudes dissipated from before the observer. — Fig. 5. 



This is a vivacious animal, as evidenced by the tentacular movements 

 and action. Sometimes their extremities close over the mouth in the 

 centre, while the circumference of the lower portion enlarges like the 

 swelling of an orange ; and their curvatures may be then compared to 

 fingers, endeavouring to seize or to confine substances contained in the 

 grasping hand. Buoyant particles are tosssed about among the cilia of 

 the tentaeula, and those of considerable size absorbed by the mouth in the 

 centre. They are visible passing downwards, on deglutition, until obscured 

 below. 



Removal from darkness induces the protrusion of the hydra to the 

 light. When perishing by impurity of the water, it drops from its site, 

 with the organs expanded. 



The natural position of leaves of the Fucus serratus, invested by the 

 Flustra hispida, is chiefly pendent, whereby its increment remains less 

 disturbed than on those inclined or horizontal. Its earlier formation is 

 circular, or in elliptical patches : and on advancing, free of obstruction, it 

 is always with a curving margin. This margin is thin and transparent, 

 within which the hydrae in retreat are seen disposed with considerable 

 regularity, like so many short lines directed from the interior towards the 

 circumference. 



The higher margin of pendent specimens seems of lighter colour, 

 being possibly newer. The older parts are of very dark olive. As the 

 Flustra, in the progress of increment, reaches the edge of the leaf of the 

 fucus invested, and projects slightly over, it becomes somewhat more 

 transparent. 



I have always found the largest, most vigorous and luxuriant speci- 

 mens abound at low water-mark, of a muddy shore. Some are seen con- 

 siderably higher ; but proportionally deteriorated, as remote from the sea. 



