LARVAE OF DECAPOD CRUSTACEA 



433 



Antennule with segments 2 and 3 equal, not much shorter than segment i. 

 Antenna short and stout, with strong pointed process on outer side of segment 2 

 of peduncle, segment 3 very much narrower than segment 2 in late stages. 



Maxillule without palp. Maxilla without setae on exopod. Maxillipedes 2 and 

 3 without functional exopods. Legs without coxal spines. Leg 3 with propodus 

 dilated at end. Leg 5 without exopod, but with small rudiment of it in late stages. 



Fig. 38. Themis sp.?, Stage IV?, 8 mm. St. 691. 



The fifteen specimens of this form are divisible into five stages, the oldest of which 

 is in the last stage but one. The growth factor for these stages is about i -26 for the oldest, 

 and increases to about 1-5 for the youngest. If this rate of growth is assumed for the 

 unknown younger stages, and if it is assumed that the first larva is about 2-5 mm. long, 

 there will then be three unknown stages, and the youngest of the Discovery specimens 

 will be in stage IV. The stages may be defined as follows : 



