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PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 39. 



thoracic in origin, while the other mouth-parts are cephalic. In the 

 internal anatomy of these metanauplii there has been a considerable 

 rearrangement of the muscles which move the appendages. Owing 

 to the insertion of muscles for the two new pairs of appendages, those 

 which move the three original pairs can not extend as far back in the 

 body as formerly, but run more directly inward from the bases of the 

 respective appendages. 



Fig. 36.— Second metanauplius just ready to molt into thk fiest copepodid stage. 



Lettering as in fig. 4, ?. 273. 



The digestive canal still retains its deep blue pigment, and at its 

 anterior end has developed a well-defined stomach, from which a 

 straight intestine of gradually decreasing width runs back to the anus. 

 This latter is situated between the anal laminae and is now distinctly 

 visible. The larva begins to eat during this period and the peristaltic 

 movements concerned in digestion are very evident. At the same 



