93 



Length of 'Siboga' females 2,9 mm. 



The known distribution at present is very limited. 



3. Scapkocalamis elongatus nov. sp. Plate XXXII, figs. 10 — 16. 



Female — length 2,9 mm. 



Seen from above, the body is elongate and narrow. The head is fused with the first 

 thoracic segment, and its combined length is nearly twice that of the three following segments 

 together. The fourth and fifth thoracic segments are completely fused. The last thoracic segment 

 is slightly produced and is distinctly pointed. Viewed from the side, the forehead appears narrowly 

 rounded. The last thoracic segment terminates in a small but distinctly curved point. The rostrum 

 is represented by two long slender filaments (Plate XXXII, fig. 13). 



The abdomen is composed is four segments. The combined length of the abdomen and 

 furca is contained two ancl two-third times in the total length of the ccphalothorax, from the 

 frontal margin to the base of the genital segment. The genital segment is slightly longer than 

 the second segment, and the anterior portion of the ventral surface is slightly produced. The 

 second and third segments are of equal length. The anal segment is equal to two-thirds of 

 the length of the third segment. The furcal joints are fully twice as long as broad, and are 

 slightly longer than the anal segment. 



The antennules were incomplete. 



The antennae, mandibles, maxillae and maxillipedes are similar to those of Scaphocalanus 

 magnus. 



The four pairs of swimming feet are also similar to those of that species. 



The fifth pair of feet consists of two free joints attached to a basal part. The first joint 

 is short. The second joint is of moderate length, and it is considerably contracted from the 

 middle to the apex. The inner marginal spine arises from the middle of the joint, and is fully 

 twice as long as the joint. The apical spine is equal to half of the length of the inner spine. 

 The outer marginal spine is placed near the apex, and is contained two and a half times in 

 the length of the apical spine. The outer marginal spine of the right foot is wanting, but this 

 is probably accidental. 



This species is easily distinguished from the other members of the genus, by the distinctly 

 pointed last thoracic segment when seen in side view, and by the shape of the second free 

 joint of the fifth foot. The forehead is faintly thickened in the middle line, which may indicate 

 a very weak crest, but the material was too limited to make certain. 



Occurrence. — One female was found in the plankton collected with the Hensen 

 vertical net at Station 148, 1000 metres to the surface. 



Genus Lophothrix Giesbrecht, 1895. 



The members of this genus are distinguished by the very short end joint of the exopodite 

 of the antennae, and by the stout bifurcate rostrum. The rami of the rostrum terminate in a 

 small spine, but there is 110 articulation between the spine and the basal portion. The female 



9 3 



