ACALEPHvE; CYDIPPE. 475 



Animalcules, freely moving by the cilia with which they are pro- 

 vided at their edges. After a time they fix themselves at one 

 extremity; and gradually become converted into Polype-like 

 animals. In this state they remain several months, obtaining 

 their food by means of long slender tentacula ; and each of these 

 polype-like bodies then separates, by transverse division, into 

 from ten to fifteen young Medusae, which gradually acquire the 

 form of the parent. 



1035. Another most interesting form is the little Cydippe 

 (formerly called Beroe\ which is often abundant on our own 

 coasts. This animal is of a nearly globu- 

 lar form, sometimes a little elongated at 

 the two extremities, and about three- 

 fourths of an inch in length. It is com- 

 posed of a delicate jelly-like substance, 

 strengthened by eight bands of somewhat 

 firmer texture, which run like meridian 

 lines from pole to pole. These bands are 

 covered with rows of large cilia, arranged 

 side by side, so as to form narrow plates 

 ?Si toS of a fin-like character. There are, in the most 

 common species, from three to seven cilia 

 in each row ; and about twenty rows on each ridge. The whole 

 ridge is not unlike the paddle-wheel of a steam-boat ; but the 

 motion is given by the vibration of the separate floats, and not 

 by the revolution of the whole. Over these floats the animal 

 has evidently complete control ; it can retard or stop their move- 

 ments at pleasure ; and arrest the play of one, two, or more rows 

 whilst the remainder continue in rapid vibration. By these 

 means it is capable of swimming through the water with consi- 

 derable activity, and of changing its course at will. The animals 

 themselves are of a bright faintly-blue aspect; and the cilia 

 present vivid iridescent hues when in motion. The mouth 

 is situated at one of the poles of the globe, and it is always 

 directed forward when the animal is in motion. It is a wide 

 entrance to the short oesophagus, which terminates in the sto- 

 mach ; it can be closed by the animal when irritated ; but when 



