178 PROCEEDINGS OF THE NATIONAL MUSEUM vol. nz 



A single row of spinules on posterior border of labrum. Paragnaths 

 of somewhat different appearance from those of thysanotus. Anterior 

 median portion of labium flowing forward to merge with roof of 

 mouth cavity; ornamentation on its surface confined to 2 irregularly 

 curved rows of denticles. Two ciliated lobes on roof of mouth cavity 

 just posterior to insertion of paragnaths. 



Mandible with curved element and blade but only 1 seta; termi- 

 nally curved element lacks incomplete roothed ridge, dentations on 

 edge stronger. 



Maxillule very similar in plan to that of thysanotus but angular 

 projection poorly developed and more dorsal in position. Some 

 differences in relative size and ciliation of setae. 



Setule-bearing seta on first segment of maxilla larger than the other; 

 terminal armature of second segment (ventral to dorsal) a strong 

 curved spine, 2 smaller ones almost side by side — the anterior notched 

 at its tip, the other strongly ciliated — and a longer spine with strong 

 cilia. 



Maxilliped with no seta on third, 2 on terminal segment: longest 

 seta on anterior side, other on base of dorsal process. (It is difficult to 

 homologize the smaller seta with any on the thysanotus maxilliped.) 

 Ventral spine bearing only 2 spinules on anteroventral surface and 

 terminating in a setule inserted near tip. Both setae on first segment 

 with very long cilia. 



Swimming legs similar to those of thysanotus except in armature, 

 which is: 



Terminal setules on spines of all exopodites; group of strong cilia on 

 base of median seta on third endopodite segment only in second and 

 third legs. 



Figure 4. — Hemicyclops adhaerens (Williams), female: a, Habitus, dorsal aspect, b, Right 

 maxilliped, dorsal (anterior) view, c, Right first swimming leg with coxal plate, ventral 

 (anterior) view, d, Right second swimming leg with coxal plate, ventral (anterior) view. 

 e, Right third swimming leg with coxal plate, ventral (anterior) view. /, Right fourth 

 swimming leg with coxal plate, ventral (anterior) view, g, Right fifth leg, ventral view. 

 h, Left sixth leg, dorsal view. *, Right caudal ramus, dorsal view. Scale B (fig. 2) applies 

 to a; E to c-f; F to b, g, and i\ and G to h. 



