24 



DE GENERA TION. 



shrimp, which is illustrated in the wood-cuts (Fig. 3 

 and right lower corner of Fig 4). The little creature 

 which issues from the tgg of this shrimp is known 

 as the "Nauplius form." Many animals very different 

 in appearance from this shrimp make their first 



Fig. 4. — >J'aupluis larval-form of various Crustacea (Shrimps, Water-fleas, 



Barnacles, &c.). 



appearance in the world as Nauplii ; and it appears 

 probable that the Nauplius-phase is the recapitula- 

 tive re-presentation of an ancestor common to all 

 this set of animals, an ancestor which was not exactly 

 like the Nauplius, but not very different from it. 

 The Nauplius of our shrimp gradually elongates. 



