i86 



The antennae, mandibles, maxillae and maxillipedes are al most similar to those of 

 Parapontella brevicornis. 



The four pairs of swimming feet are also nearly similar to those of Parapontella. The 

 exopodites are three-jointed. The endopodite of the first pair is three-jointed. The endopodites 

 of the second, third and fourth pairs are two-jointed. The outer edge spines on the joints of 

 the exopodite of the second, third and fourth pairs of feet are coarsely spinulose. The terminal 

 spine on the last joint of the exopodites of the second, third and fourth pairs of feet is coarsely 

 serrate (Plate LV, fig. 11). 



The fifth pair is symmetrical. Each foot is composed of a two-jointed basiopodite, and 

 a one-jointed exopodite. The apex of the exopodite is armed with three strong spines. The 

 middle spine is considerably longer than the other two spines. The inner spine is short and 

 very stout. It is equal to nearly twice the length of the outer spine. The inner margin is 

 fringed with a few short hairs. There is no outer edge spine as in Parapontella brevicornis. 

 The fifth pair of feet has no tracé of an endopodite (Plate LV, fig. 12). 



Male — length 1 mm. 



The male differs very little in general appearance from the female. The abdomen is 

 composed of four segments. The segments are without armature of any kind (Plate LV, fig. 13). 



The right antennule is somewhat similar to that of Parapontella brevicornis, but the 

 last joint is not produced into a tooth-like process as in that species. The proximal hinge joint 

 has no serrated lamina (Plate LV, fig. 14). 



The antennae, mandibles, maxillae, maxillipedes and first four pairs of swimming feet 

 are similar to those of the female. 



The fifth pair of feet is asymmetrical. The last joint of the right and left foot is 

 lamelliform. The last joint of the right foot has a claw-like appearance, but there is no articulation 

 between the inner thumb-like process and the palm. The outer margin of the last joint of each 

 foot is furnished with two spines. The apex is spiniform (Plate LV, fig. 15). 



This species is easily recognised by the structure of the fifth pairs of feet of the two sexes. 



Occurrence. - - Four females and one male were obtained from the plankton collected 

 with the Hensen vertical net at Station 143, 1000 metres to the surface. 



20. Family Acartiidae. 

 Genus Acartia Dana, 1846. 



This was the only member of the family obtained from the plankton collected during 

 the traverse of the 'Siboga' in the Malay Archipelago. 



Representatives of the closely allied genus Paracartia have been found in the plankton 

 of the Gulf of Guinea, the Antarctic, and from off the coast of Norway. Future research may 

 reveal the presence of this genus in the plankton of the Indian and Pacific Oceans. Wolfenden, 

 in the results of the British 'National Antarctic Expedition' Natural History, Vol. IV, Zoology, 



186 



