182 ANATOMICAL DESCRIPTIONS. [December. 



The circumference of this last cavity is furnished with 

 strong cylindric muscles, which act, like strings to a 

 a purse, in drawing the borders together. 



The exterior tubercles, which are very apparent on 

 the divisions, seem to establish a communication between 

 the internal and external parts, and admit the water into 

 the cells formed by the interior membrane. I had an op- 

 portunity of observing, in several species of Actinia, the 

 water ejected through similar apertures, when the animals 

 contracted themselves. The air-bladder disc is formed of 

 a multitude of small membranes, placed one on another, 

 the largest at the upper part, the rest diminishing in size 

 to the point where this disc is in contact with the bottom 

 of the cavity; its membranes in this place are solid, and 

 pressed together, particularly towards the centre, where 

 is a small conic, hard, opaque nucleus, whence these 

 membranes seem to have their origin, and form the disc. 

 This air-bladder disc is easily separated from the cavity 

 which encloses it. 



Actinia jiava. (Plate VII. fig. 9.) The interior or- 

 ganization of this species resembles somewhat that of the 

 preceding. The ovaries are attached equally to the strong 

 organ of longitudinal fibres, they are folded on the same, 

 and when they open one perceives numerous small trans- 

 verse fibres, with a yellow substance which fills them. 

 On their borders rise a very plaited membrane, whereon 

 one can distinguish small granulations, resembling eggs. 

 The stomach is equally surrounded, and supported, by 

 this organ and its membranes, forming as many cells, 

 which are prolonged as far as the end of the tentacula, 

 which have at their points a small aperture; these small 

 apertures are analogous to those which are situate on the 



