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fifth pair of feet is composed of two free joints attached to a basal part. The second joint is 
furnished with one apical and two subapical spines. 
The male has hitherto been unknown and is described below for the first time. The 
exopodite of the right and left fifth foot is three-jointed. The endopodite is present on each 
foot and is composed of a single joint. 
GiEsBRECHT described the genus in 1895, but it was withdrawn on the publication of 
the part on the Copepoda in ‘Das Tierreich’ in 1898. The genus has since been revived and 
set aside at intervals, but with the discovery of the male, the position of Lophothrix as a 
separate genus now appears to be firmly established. 
The type species only, was represented in the plankton collected by the ‘Siboga’. 
1. Lophothrix frontalés Giesbrecht. Plate XXVI, figs. 11—20 (female). Plate XXIX, 
figs. I—10 (male). 
Lophothrix frontalis Giesbrecht, 1895, p. 254, pl. II. 
Scolecithrix frontalis Giesbrecht & Schmeil, 1898, p. 4o. 
Scolecithrix frontalis 1. C. Thompson, 1903, p. 21. 
Lophothrix frontalis Wolfenden, 1904, p. 111, pl. IX. 
Lophothrix frontalis Sars, 1905(a), p. 6. 
Lophothrix frontalis Pearson, 1906, p. 19. 
Scolecithrix frontalis Esterly, 1906, p. 65, pls. 9 & 13. 
Lophothrix frontalis Farran, 1908, p. 58. 
Scolecithrix frontalis van Breemen, 1908, p. 79, fig. 93. 
Ten females and two males were obtained from the plankton collected at the following stations. 
Stat. 118 (HENSEN vertical net 900 metres to surface), 1 specimen. — Stat. 128 (HENSEN vertical 
net 700 metres to surface), 1 specimen. — Stat. 141 (HENSEN vertical net 1500 metres to 
surface), I specimen. — Stat. 148 (HENSEN vertical net 1000 metres to surface), 1 specimen. — 
Stat. 168 1 specimen. — Stat. 184, I specimen. — Stat. 185 (HENSEN vertical net 1536 
metres to surface), 1 specimen. — Stat. 203 (HENSEN vertical net 1500 metres to surface), 
2 specimens. — Stat. 243 (HENSEN vertical net 1000 metres to surface), I specimen. — 
Stat. 276: — (HENSEN vertical net 750 metres to surface), I specimen. 
The female is easily identified by the moderately high and narrowly rounded median 
crest on the forehead, when viewed from the side; — By the stout bifurcate rostrum and the small 
spine at the apex of the rami, and by the structure of the fifth feet. The two free joints are 
comparatively short. The second joint is distinctly expanded near the apex and bears three 
spines, one apical and two subapical. The inner subapical spine is moderately long and somewhat 
irregular in shape. The apical spine is slightly curved inwards, and is equal to two-thirds of 
the length of the inner subapical spine. The outer subapical spine is about half the length of 
the apical spine. The three spines are fringed with fine spinules. Length of female 7,4 mm. 
The male has only a slight resemblance to the female. Viewed from above it appears 
elongate in outline. The fourth and fifth thoracic segments are fused, and the junction is marked 
by a sudden constriction near the posterior end. The apex of the segment is lamelliform and 
pointed. Seen from the side, the forehead is furnished with a low rounded median crest, and 
a moderately strong rostrum. The last thoracic segment is narrowly rounded, with a slight 
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