ACALEPEJE. 379 



in abundance the beautiful Acalephce. From some of them 

 having a remarkable stinging property, they have derived 

 their name of Sea-nettles, while others, from their gelati- 

 nous nature, are better known as Sea-jelly, 

 or Jelly-fish. 



These interesting animals were first 

 arranged in three orders : A. stabiles (fixed), 

 A. liberce (free), and A. hydrostaticce (hy- 

 drostatic). Cuvier classed them in two 

 orders : A. simplices, and A. hydrostaticce. 

 They are now, however, divided differently, 

 and arranged in groups according to the 

 peculiar mode by which they effect their 

 locomotion. A very interesting point of 

 connexion between this class and the 

 preceding-, is the interchange of form. 



* AI. v -L j. XT. m 7 Fig.196. A Jelly-fish. 



Some of the Zoophyta, as the Tubu- 

 lariadce and the Campanulariadce, give birth to a progeny 

 which are in every respect Naked-eyed Medusae; while, on 

 the other hand, the young of the Medusa, are, in their 

 earlier stages stationary polypes. 



The Medusae spread on the surface of the water a beau- 

 tiful jelly-like mass, that in form resembles an umbrella ; 

 arid by a continual contraction and opening out of this 

 part, they pass along in the path they desire. They are all 

 more or less phosphorescent. The Beroe, like many of the 

 Infusoria, propel themselves with active ciliated arms. 

 The Physalidce have an organ common to fishes, swim- 

 ming bladders, by filling or emptying which they rise or 

 sink, and move along in their watery home. 



The Portuguese Men-of- War have a large bladder, which, 

 when filled with air, rises above the surface of the waves, 

 and is propelled by the wind a contrivance something 

 similar to, though more successful, we suspect, than the pro- 

 position to drag along land-carriages by means of balloons. 



The flat circular horny disc forming the skeleton of 

 Propita gigantea, to the naked eye exhibits both radiating 

 and concentric markings ; and when examined with a 

 power of 40 diameters, its upper surface is found to be 

 furrowed, and two rows of small projecting spines occur 

 upon the ridges between the furrows, the ridges being the 

 radiating fibres above noticed. The under-surface, or that 



