4O Invertebrata. 



depending from the centre of a large disk or umbrella 

 varying from an inch to three feet in diameter. The 

 mouth of the polypite is surrounded by lobate tenta- 

 cles (fig. 24), and from the stomach there pass eight or 

 more branching radial canals which are united peri, 

 pherally by a circular canal. The eggs are produced in 

 pouches of the stomach-cavity, and each of these on 

 ripening emits a ciliated germ like an infusorium but 

 multicellular (fig. 24 b\ which after a brief locomotory 

 existence settles down on some solid body at the sea 

 bottom (c}> and develops a hydra-like animal with 



Medusa turita in different stages of life ; a perfect adult form reduced T \ i 

 6, c, d hydra-like staye ; *?,_/"nssion stages ;^one of the disks separated 

 from f, and growing into adult form. 



branching canals which, elongating, forms a little rooted 

 colony (d). Each of these hydra-like forms becomes 

 marked with transverse farrows (e) which, deepening, 

 dip into the interior of the body dividing it into a ver- 

 tical ' pile of saucers/ of which each discoidal segment 

 becomes in process of time free as a new medusa. 

 This is a good example of alternate generations. 



