194 TUB OCEAN WORLD. 



at the bottom of the sea, turns itself inwards, forming a sort of purse, 

 which seems to imprison the air. From this results a sort of hydro- 

 static apparatus, aided by which the animals can float in the water and 

 transport themselves from one place to another. The Blue Minyade 

 (Minyas cyanea Fig. 83) will serve as a type of this family ; its 

 globose, melon-like form is of azure blue, studded with white wart-like 

 excrescences ; it is flattened at its two extremities in its state of con- 

 traction, and it has three rows of tentacula, which are short, cylindrical, 

 and white. The internal organs are of a delicate rose colour. Cuvier 

 places this species among the Echinodermata, but the observations of 

 Lesueur and Quoy, who were acquainted with the living animal, place 

 it among the Actiniadse. Many of the species, which are usually 

 fixed, are still capable of swimming and of inflating their suctorial 

 disks ; therefore it is by no means certain that the free habit of Minyas 

 cyanea is constant, 



