THE SYNC ARID A 



165 



In all except the last pair of thoracic limbs the coxopodite 

 bears externally two ovate epipodial lamellae, each attached by a 

 narrow base and having a small proximal segment marked off by a 



A. 



/--p. 



B. 



transverse line. These epipodites 

 have a very thin cuticle and no 

 doubt act as gills. 



Exopodites are present on all 

 but the last (Anaspides) or the 

 last two (Koonunga) pairs of tho- 

 racic appendages. On the first 

 pair they are short, unsegmented 

 rods, but on the other limbs they 

 are many-jointed and fringed with 

 plumose setae. According to G. 

 Smith they are not used in swim- 

 ming, but serve to keep a current 

 of water flowing over the branchial 

 plates. 



The first pair of thoracic limbs 

 in Anaspides (Fig. 3, D, p. 8) are 

 differentiated from the others by 

 the presence on the inner face 

 of the coxopodite of two movably 

 articulated gnathobasic lobes (gn). In Koonunga these lobes are 

 wanting, but the limb differs from those which follow it in being 

 much more stoutly built. 



The pleopods have the exopodite long, many-jointed, and fringed 

 with setae, forming a powerful swimming-organ. The endopodite 

 (except in the first two pairs of the male) is small and composed 

 of two segments in Anaspides, and entirely absent in Koonunga. 



Mouth-parts of Anttxpides. A, man- 

 dible ; B, maxillula ; C, maxilla. e.r, 

 cxitf ; /, incisor process ; m, molar pro- 

 eesa ; j>, palp; s, setose lobe. 



