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Seventeen specimens of this species were obtained from the plankton collected at the 
following stations. 
Stat. 16, 3 specimens. — Stat. 35, 4 specimens. — Stat. 217, 3 specimens. — Stat. 271, 
4 specimens. — Stat. 304, 3 specimens. 
Microsetella rosea is readily distinguished from JZzcrosetella atlantica by its larger size, 
by the very long furcal setae, and by the form of the fifth pair of feet. 
This JZicrosetella has a moderately wide distribution in all the great oceans. 
26. Family HaARpaAcrIcIDAE. 
Genus Harpacticus M. Edwards, 1838. 
The feature that separates this genus from the other members of the family is the 
peculiar transformation of the exopodite of the third pair of feet of the male. The exopodite 
of this pair forms a powerful prehensile appendage. | 
Three species were obtained from the plankton collected by the ‘Siboga’ in the Malay 
Archipelago. Two of the species do not appear to have previously been described. 
1. Harpacticus cristatus nov. sp. Plate LXI, figs. 1—8. 
Female — length .49 mm. 
Seen from above, the body appears rather slender and depressed. It resembles a Laophonte 
in general appearance. The cephalic segment is large and is provided with a distinct crest 
traversing the whole of the middle line. The crest is quite obvious both in the lateral and 
dorsal positions (Plate LXI, figs. 1 & 2). The anterior portion of the ventral margin is considerably 
expanded as shewn in the illustration. The rostrum is. moderately wide. The apex is bluntly 
rounded. The ventral margins of the thoracic segments are distinctly pointed at the distal ends. 
The abdomen is composed of four segments. The combined length of the abdominal 
segments and furcal joints is contained fully twice in the total length of the cephalothorax, 
from the apex of the rostrum to the end of the last thoracic segment. The genital segment 
is moderately large. It is equal to the combined length of the next two segments. The ventral 
surface is traversed by a distinct suture. The second and third segments are of nearly equal 
length, but the lateral margins of the third segment appear rather hollowed out. The furcal 
joints are longer than broad (Plate LXI, fig. 8). . 
The antennules are composed of eight joints. The first four joints are long and narrow. 
The last four joints are very short The combined length of the last four joints is only about 
one-seventh of the combined length of the first four joints. 
The antennae, mandibles, maxillae, and first pair of maxillipedes resemble those of 
Harpacticus chelifer (Miller). The second joint of the second pair of maxillipedes is long and very 
slender. The terminal claw is also long and slender. It is much longer than the second joint. 
The first pair of feet is rather slender. The exopodite is much longer than the endopodite. 
The first joint of the exopodite is short. Its length is contained two and one-half times in the 
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