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MUSEUM OF COMPARATIVE ZOOLOGY. 329 



Plate III. 



Fourth larval stage ; cephalo-thorax, from below. 



The same ; penultimate thoracic appendage. 



The same ; last thoracic appendage. 



Fifth larval stage ; cephalo-thorax viewed from below, sp, spinous 



process of second pair of antennre. 

 The same ; anterior part of the carapace. 

 The same ; fifth abdominal somite, viewed from the side. 

 The same ; labrum (I b) and mandibles (III). 

 The same ; second maxilla. 



The same ; natatory branch of the tenth pair of appendages. 

 The same ; abdominal appendage of the first pair. 

 The same ; abdominal appendage of the second pair (those of the 



third and fourth pairs have the same form). 

 The same ; abdominal appendage of the fifth pair. 

 The same ; telson and swimmerets. 

 Sixth larval stage, one moult after the fifth larval stage ; antenna of 



the second pair; sp, spinous process. 

 The same ; first cheliped. 

 The same ; second cheliped. 

 The same ; one of the abdominal appendages. 

 The same ; telson and swimmerets. 



Plate IV. 



[Note. Figs. 9-11 are from drawings by Mr. A. Agassiz.] 

 Sixth larval stage, two moults after the fifth larval stage, lateral view. 

 The same ; second antenna; sp, spinous process. 

 The same ; cheliped with its external, natatory branch (r e). 

 The same ; first abdominal appendage. 

 The same ; second abdominal appendage. 

 The same ; posterior margin of the telson. 

 Sixth larval stage, three moults after the fifth larval stage ; anterior 



end of first antenna. 

 The same ; telson and swimmeret. 

 Seventh larval stage ; rostrum and eye. 

 The same ; second maxilliped. 

 The same ; third maxilliped. 

 The same ; chela. 



The same ; rudimentary external branch (re) of thoracic legs. 

 The same ; posterior thoracic leg. 

 Young prawn, 8 mm. long, which has acquired most of the characters 



of the adult. 

 Adult ; third maxilliped. 

 The same ; scale of second antenna. 



