82 THE LIFE OF CRUSTACEA 



has only the first three pairs of appendages, and is 

 therefore regarded as a nauplius, although it possesses 

 a bivalved shell like that of the adult, and is very 

 unlike the nauplius larvae of other Crustacea. 



Most of the Copepoda also leave the egg in the 

 nauplius stage ; and, indeed, it was to the young of 

 the common fresh-water Cyclops (Fig. 34) that the 

 name of Nauplius was first given by the Danish 



FIG. 34 EARLY NAUPLIUS LARVA OF A COPEPOD (Cyclops). MUCH 

 ENLARGED. (From Lankester's " Treatise on Zoology.") 



a', Antennule ; a", antenna ; gn, jaw-spine of antenna ; Ibr, upper 

 lip ; md, mandible 



naturalist, O. F. Muller, in the eighteenth century, 

 in the belief that it was an adult and independent 

 species of Crustacea. In the Copepoda, the changes 

 which transform the nauplius into the adult are 

 gradual, and consist chiefly in the successive addition 

 of new somites and appendages. 



The development of the Cirripedia is of special 



