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bifurcate base. The antennules are composed of twenty-three joints. The antennae, mandibles, 
maxillae and maxillipedes are similar in structure to those of the genus Scolectthricella. The four 
pairs of swimming feet are also similar to those of that genus. The fifth pair is very small. 
Each foot is composed of a single joint attached to a basal part. 
Male. In general appearance it resembles the female. The frontal lens-like organ is 
present. The rostral filaments are much longer and the basal part may possess a small secondary 
apical spine. The antennules are composed of twenty joints. The antennae, mandibles, maxillae 
and maxillipedes are similar to those of the female and are not modified. The four pairs of 
swimming feet are also similar to those of the female, but the surface of the joints is less 
spinulose. The fifth pair is well developed and prehensile. The basiopodite is two-jointed. The 
exopodites of both feet are composed of two joints. The first joint of the right exopodite has 
the basal part more or less produced internally. The second joint is forked. The apex of the 
second joint of the left exopodite is furnished with a spine, and a tuft of hairs. The endopodite 
is present on each foot, and is composed of a single joint. 
The form described by GiEsprecuT in 1896 as Scolecethrix chelipes, undoubtedly belongs 
to this genus. I have compared specimens of it that were found in plankton samples taken by 
Professor HeRDMAN in the Red Sea, during his traverse to Ceylon in 1903. The male fifth pair 
of these specimens is identical with Girsprecur’s figure, and the forehead possesses the frontal 
lens-like organ referred to above. 
The peculiar lens-like organ on the forehead of both sexes, along with the structure of 
the male fifth pair of feet, readily separates this genus from any of the other members of the family. 
One species belonging to this new genus was found in the plankton collected by the 
‘Siboga’. Both male and female were obtained. The species is distinct from GuIESBRECHT’s 
Macandrewella (Scolectthrix) chelrpes. 
1. Macandrewella joanae nov. sp. Plate VI, figs. 12—23 (female). Plate XXIII, figs. 
9—15 (male). 
Female — length 3,6 mm. 
Seen from above, the body is oval and robust. The head is considerably contracted in 
front, and the last thoracic segment is quite asymmetrical. Each side of the thoracic segment 
is produced, and terminates in a curved spine. The spine of the left side is longer than the 
one on the right, side (Plate VI, fig. 12). Viewed from the side, the forehead appears rounded 
and possesses a distinct lens-like organ, situated just behind the base of the rostrum. In end 
view the organ is circular and chitinised (Plate VI, fig. 16). The left side of the last thoracic 
segment is boldly but narrowly rounded, and is produced into a terminal curved spine, which 
extends beyond the middle of the genital segment. The upper basal part of the spine forms 
a distinct indentation with the dorsal margin (Plate VI, fig. 14). The right side of the last 
thoracic segment is also boldly rounded, but the curved spine only reaches to the middle of the 
genital segment. The basal part of the spine forms a distinct tooth with the dorsal margin of 
the segment (Plate VI, fig. 15). The rostrum has a stout bifurcate base, and each ramus has 
a filament articulated to it. 
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