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Occurrence. — Two females were found in the plankton collected at Station 213. 

 The fifth pairs of feet of the two specimens were identical. 



The triangular spine under each eye in the two species now described is readily seen 

 when the Copepod is so placed that it rests midway between the dorsal and lateral positions. 



Tribe AMPHARTHRANDRIA. 



22. Family Mormonillidae. 



Genus Mormonilla Giesbrecht, 1891. 



The members of this genus are readily distinguished by their transparent, elongate 

 narrow body, by the slender abdomen, and by the long furcal joints. The antennules are 

 composed of three or four joints, and are furnished with very long setae. The structure of the 

 other appendages is also characteristic of the genus. 



One species was represented in the plankton collected by the 'Siboga'. 



1 . Mormonilla phasma Giesbrecht. 



Mormonilla phasma Giesbrecht, 1891, pp. 474 & 475. 

 Mormonilla phasma Giesbrecht, 1893, p. 532, pi. 43. 

 Mormonilla phasma T. Scott, 1893, p. 64, pi. VII, figs. ir — 21. 

 Mormonilla phasma I. C. Thompson, 1903, p. 31. 

 Mormonilla phasma Farran, 1908, p. 88. 

 Mormonilla phasma van Breemen, 1908, p. 166, fig. 181. 



Six females belonging to this species were obtained from the plankton collected at the 

 following stations. 



Stat. 1 18 (HENSEN vertical net, 900 metres to surface), 2 specimens. — Stat. 143 (Hensen vertical 

 net, 1000 metres to surface), 2 specimens. — Stat. 203 (HENSEN vertical net, 1500 metres 

 to surface), 1 specimen. — Stat 205, 1 specimen. 



The last joint of the antennules of this species is equal to very little more than half 

 the length of the second last joint. In Mormonilla minor Giesbrecht, the last joint of the 

 antennules is as long as the second last joint. 



Mormonilla phasma has been recorded from the Atlantic and Pacific Oceans. 



23. Family Oithonidae. 

 Genus Oithona Baird, 1S43. 



The members of this well known genus are readily recognised by the very elongate ovate 

 and transparent body, and by the moderately long abdomen. The structure of the mandible 

 palp and of the second pair of maxillipedes is quite distinct from that found in Cyclops. This 



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51BOGA-EXPEDITIE XXIX (7. 



