DEVELOPMENT OF THE LOBSTER 



183 



embryo or larva, termed the nauplius. This larva has little 

 resemblance to the parent, consisting of a small ovoidal body, 

 with mouth, three pairs of biramous appendages and a median 

 unpaired simple eye (Fig. 77). The appendages are the first 

 three pairs of the adult, and in this stage have little similarity to 

 the later antennules antennae and mandibles. Each consists 

 of exopodite, endopodite and protopodite, which, with develop- 

 ment of the larva, become transformed into the specialized 

 organs of the head. 



FIG. 78. "Mysis" stage in the development of the lobster; a stage in which 

 the thoracic appendages are all biramous (cf. Fig. 87). (From Herrick.) 



Growth of the larva results in elongation of the body and the 

 formation of somites at the posterior end. The terminal somite 

 is formed first, and new somites are added by a process of growth, 

 analogous to budding, which occurs between this terminal so- 

 mite and the body. After each somite is .thus formed, paired 

 biramous appendages develop on it as outgrowths. A larval 

 form thus develops from the nauplius, in which all of the appen- 



