KNIGHT: STAGES OF THYSANOPODA TRICUSPIDATA 



0, 1 mm 

 I 1 



a-d 



Figure 4. — Antennule, right, dorsal view: a, nauplius; b, metanauplius; c-e, calyptopes I-III. 



Antennule (Figure 4b) now with 3 terminal 

 processes, there is a small seta or sensory fil- 

 ament in place of spiny lobe; surface spinules 

 appear to be organized into fewer simpler rows. 



Antenna (Figure 5b) with protopod segment- 

 ed into coxa and basis, there are a few spinules 

 on inner distal margin of each; endopod with 4 

 terminal setae — 1 seta is relatively short, and 2 

 setae on inner margin — the proximal seta is 

 short to rudimentary; exopod with 5 short term- 



inal segments but without proximal segmenta- 

 tion of outer margin seen in nauplius, the seta- 

 tion is unchanged although there may be a spin- 

 ous rudiment of third seta on terminal segment. 



Mandible (Figure 6b) reduced to rounded lobe 

 bearing pointed lateral process, 



Maxillule, maxilla, and maxilliped are repre- 

 sented only be rounded prominences. In spe- 

 cimens nearing molt, the rudimentary spines on 

 endopod and endites of developing maxillules and 



59 



