212 



COMPARATIVE ZOOLOGY. 



Fig. 177.— Nau plius of Entornostracan (Canthocamptus). See Fig. 255. A, first an- 

 tenna ; An, second antenna; a, anus ; L, labrum ; 0, ocellus ; S, stomach. (From 

 Brooks, after Hoek.) 



other words, the parent may find no resemblance to him- 

 self in any of his progeny, until he comes down to the 

 great-grandson." Thus, the Jelly-fish, or Medusa, lays 

 eggs which are hatched into larvse resembling Infusoria — 

 little transparent oval bodies covered with cilia, by which 

 they swim about for a time till they find a resting-place. 

 One of them, for example, becoming fixed, develops rap- 

 idly ; it elongates and spreads at the upper end; a mouth 

 is formed, opening into a digestive cavity ; and tentacles 

 multiply till the mouth is surrounded by them. At this 

 stage it resembles a Hydra. Then slight wrinkles appear 

 along the body, which grow deeper and deeper, till the 

 animal looks like "a pine-cone surmounted by a tuft of 

 tentacles and then like a pile of saucers (about a dozen 



