450 THE AQUARIAN NATURALIST. 



preserved, correct delineations having been made of 

 several of them. They all disappeared just as the 

 former had done ; but this time it was observed that 

 various minute circular spots made their appearance, 

 not unlike those which generally indicate originating 

 Zoophytes, and these remained on the internal surface 

 of the vessels wherein the Spinula had been confined. 



In subsequent observations, the Spinula having 

 continued healthy, active, and vigorous for a certain 

 time, some of them were seen with their heads applied 

 to the bottom of the vessel, the tail being upright 

 and stationary, as if they were enjoying a state of 

 perfect repose in this inverted erect position. Mean- 

 time, the front may be observed to be enlarging ; it 

 seems hollow ; the margin at the same time dividing 

 into angular projections; and incipient adhesion to 

 the glass ensues. Now the animal is no longer 

 tranquil; its violent struggles testify that it is un- 

 wittingly or unwillingly arrested; its exertions are 

 vehement to be free. At this juncture the vibrations 

 of the tail become so rapid, that, like those of a cord 

 in tension, its figure is hardly discernible by the eye ; 

 at length quiescence follows, some diffusing matter 

 escapes from the margin of the flattened head, and 

 the Spinula is rooted irreversibly to the spot. A 

 dark, solid nucleus is substituted for the adhering 

 head ; the tail has vanished ; a transparent marginal 

 diffusion surrounds the front where applied to the 

 glass, towards the circumference of which are distri- 

 buted numerous flattened radicles diverging from the 

 nucleus as from a centre (PI. VIII. fig. 4). 



As the nucleus consolidates, two nipples with 



