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Onchocalanus cristatus is easily recognised by the presence of a median cephalic crest, 
and by the distinct point at the distal ends of the last thoracic segment. The fifth pair of feet 
of the female consists of two free joints attached to a basal part. The second free joint terminates 
in a strong spine. The outer margin of the joint is furnished with two spines and the inner 
margin with one. Length 6,6 mm. . 
Onchocalanus cristatus has been hitherto only obtained from the deep water of the North 
Atlantic, where it appears to be not uncommon. 
2. Onchocalanus hirtipes Sars. Plate XXXIV, figs. g—17. 
Onchocalanus hirtipes Sars, 1905 (a), p. 20. 
Onchocalanus hirtipes Farran, 1908, p. 49. 
One female apparently identical with this species, was obtained from the plankton 
collected with the Hrnsen vertical net at Station 185, 1536 metres to the surface. 
Onchocalanus hirtipes has a general resemblance to Oxchocalanus cristatus, but it can 
be distinguished from it by the absence of a median crest. The last thoracic segment is obtusely 
triangular in outline when seen from the side, but it is not produced into a spine at the posterior 
margin. The rami of the rostrum apparently terminate in a filament, but only the base was 
visible in the preparation. -The fifth pair of feet is somewhat similar to that of the previous 
species. There is only one outer-edge spine on the second free joint and none on the inside. 
Length — 5 mm. 
This species has only been recorded from the North Atlantic. 
Genus Cornucalanus Wolfenden, 1905. 
This eenus was established by WoLFENDEN in 1905 for a Calanoid closely related to 
- Xanthocalanus. It is distinguished by the possession of a cephalic spine, and the apex of the 
first maxillipedes is furnished with a very powerful curved claw. 
The cephalic spine may only be a specific difference between WoOLFENDEN’s type species 
Cornucalanus magnus (= Scolectthrix chelifer 1. C. Thompson, 1903) and another form: very 
briefly described along with the type. The appendages of the second species are identical with 
those of the type, but the cephalic spine is absent. 
A form apparently identical with WoLFenpENn’s second species was found in the plankton 
collected by the ‘Siboga’. 
1. Cornucalanus simplex WNolfenden. Plate XXXV, figs. 1—9. 
Cornucalanus simplex WNolfenden, 1905, p. 22. 
Cornucalanus simplex Sars, 1907 (@), p. 14. 
Female — length 5 mm. 
Viewed from above, the body appears moderately robust, and elongate ovate in outline. 
The head is separated from the first thoracic segment. The fourth and fifth thoracic segments 
are completely separated. The last thoracic segment is produced posteriorly into points. Seen 
from the side, the forehead is only slightly arched, and no trace of a cephalic spine can be 
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