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The endopodite of the first pair of feet is composed of three joints. 



The second, third and fourth pairs of feet are of the normal Pontclla form. 



The fifth pair is moderately large. The thumb-like process on the proximal end of the 

 hrst joint of the right exopodite is very long. It is curved inwards. The middle of the joint is 

 provided vvith a nearly straight spine. The claw-like joint is long and slender and is much curved. 

 It is furnished with two inarginal spines and one apical spine. The last joint of the exopodite 

 of the left foot bears three moderately strong apical spines. The inner margin has a large pad 

 of fine hairs. The outer dorso-lateral margin is furnished with a small spine (Plate LIII, fig. 15). 



Female unknown. 



This species may easily be passed over as the male of Pontclla seairifer, as it resembles 

 it in the possession of a circular lens in the base of the rostrum, and also of a serrate plate 

 on the proximal hinge joint of the right antennule. The structure of the fifth pair of feet. 

 however, is quite distinct. 



O ecu r re nee. - Two specimens were found in the plankton collected with the Hensen 

 vertical net at Station 203, 1500 metres to the surface. 



Genus Labidocera Lubbock, 1853. 



The members of this genus are closely related to Pontclla, but they can readily be 

 separated by the structure of the first pair of feet. The endopodite of the first pair is two-jointed, 

 like the endopodites of the second, third and fourth pairs of feet. The cephalic segment is 

 usually without side hooks. One pair of dorsal eye lenses is present. The basal part of the 

 rostrum has no lens. 



Seven species of Labidocera were represented in the plankton collected by the 'Siboga' 

 in the Malay Archipelago. Two of the species do not appear to have previously been described. 



1 . Labidocera acnta (Dana). 



Pontclla acnta Dana, 1849, P- 3°- 



Pontellina acnta Dana, 1S52, p. 11 50, pi. 80. 



Pontclla acnta Brady, 1883, p. 89, pi. XXXVI, figs. 1 — 12. 



Labidocera acutum Giesbrecht, 1893, p. 445, pi. 23, 25 & 41. 



Labidocera acnta T. Scott, 1S93, p. 85. 



Labidocera acutum Giesbrecht, 1895, p. 259. 



Labidocera acnta Giesbrecht & Schmeil. 1898, p. 134. 



Labidocera acnta I. C. Thompson, 1900, p. 282. 



Labidocera acutum Geve, 1901, p. 7. 



Labidocera acnta A. Scott, 1902, p. 407. 



Labidocera acnta Thompson & Scott, 1903, p. 251. 



Labidocera acutum Geve, 1903, p. 363. 



Labidocera acnta Geve, 1904, p. 191. 



Labidocera acnta Wolfenden, 1905 (a), p. 1016. 



Labidocera acnta van Breemen, 1908, p. 150, fig. 168. 



This species proved to be moderately common. It was widely distributed throughout the 

 area investigated as shewn by the following records. 



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