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fïfth pair of teet 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 fïfth loot is three-jointed. The endopodite is present on each 

 foot and is composed of a single joint. 



Giesbrecht described the genus in 1S95, but it was withdrawn on the publication of 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 frontalis Giesbrecht. Plate XXVI, figs. 11 — 20 (female). Plate XXIX, 



figs. 1 — 10 (male). 



Lophothrix frontalis Giesbrecht, 1895, p. 254, pi. II. 



Scolecithrix frontalis Giesbrecht & Schmeil, 1898, p. 49. 



Scolecitkrix frontalis I. C. Thompson, 1903, p. 21. 



Lophothrix frontalis Wollenden, 1904, p. 111, pi. IX. 



Lophothrix frontalis Sars, 1905(0), p. 6. 



Lophothrix frontalis Pearson, 1906, p. 19. 



Scolecithrix frontalis Esterly, 1906, p. 65, pis. 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 (Hensex vertical net 900 metres to surface), 1 specimen. — Stat. 12S (Hexsex vertical 

 net 700 metres to surface), 1 specimen. — Stat. 141 (HEXSEX vertical net [500 metres to 

 surface), 1 specimen. — Stat. 148 (Hkx>EX vertical net 1000 metres to surface), 1 specimen. — 

 Stat. 168 1 specimen. — Stat. 184, 1 specimen. — Stat. 185 (Hexsex vertical net 1536 

 metres to surface), 1 specimen. — Stat. 203 (Hexsex vertical net 1500 metres to surface), 

 2 specimens. — Stat. 243 (HENSEN vertical net 1000 metres to surface), 1 specimen. — 

 Stat. 276. — (Hex>ex vertical net 750 metres to surface), 1 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 fïfth 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 fïfth 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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