241 
proportional length of the abdominal segments, and by the structure of the fifth pair of feet. 
Occurrence. — Three specimens were obtained from the plankton collected at Station 
99, off North Ubian, Sulu Islands. 
Tribe ISOKERANDRIA. 
41. Family ONCcAEIDAE. 
Genus Oncaea Philippi, 1843. 
The members of this genus can readily be recognised by their rather pyriform body. 
The forehead is furnished with a pair of eye-lenses. The abdomen is composed of four segments 
in the female. The antennules are six-jointed. 
The males resemble the females in general appearance, but the abdomen is composed 
of five segments. 
Five species belonging to this genus were represented in the plankton collected by the 
‘Siboga’ in the Malay Archipelago. 
1. Oncaea contfera Giesbrecht. 
Oncaea contfera Giesbrecht, 1891, p. 477. 
Oncaea conifera Giesbrecht, 1892, p. 591, pls. 2 & 47. 
Oncaea conifera 1. C. Thompson, 1900, p. 287. 
Oncaea conifera Cleve, 1901, p. 8. 
Oncaea conifera A. Scott, 1902, p. 418. 
Oncaea contfera Giesbrecht, 1903, p. 41. 
Oncaea conifera Thompson & Scott, 1903, p. 285. 
Oncaea conifera Cleve, 1903, p. 365. 
Oncaea conifera Cleve, 1904, p. 193. 
Oncaea conifera Farran, 1905, p. 47. 
Oncaea conifera Esterly, 1905, p. 216, fig. 55. 
Oncaea conifera Wolfenden, 1905 (2), p. 1029. 
Oncaea contfera Pearson, 1906, p. 25. 
Oncaea conifera Farran, 1908, p. 92. 
Oncaea conifera van Breemen, 1908, p. 189, fig. 202. 
This species appeared to be rather scarce in the area investigated by the ‘Siboga’. It 
was only noted at the following three stations. 
Stat. 47”, 11 specimens. — Stat. 141 (HENSEN vertical net, 1500 metres to surface), 2 speci- 
mens. — Stat. 143 (HENSEN vertical net, 1000 metres to surface), 24 specimens. 
Oncaea conifera can readily be recognised by the evenly contracted and sloping sides 
of the genital segment of the female, by the second abdominal segment being distinctly longer 
than the third segment, and by the furcal joints being as long as the anal segment. 
This species appears to have a wide distribution in all parts of the great oceans. It 
has previously been recorded from the Malay Archipelago. 
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SIBOGA-EXPEDITIE XXIX@. 31 
