53 

 i. Gaidiopsis crassirostris nov. sp. Plate VII, figs. 12—22. 



Female — length 3 mm. 



Seen from above, the cepkalothorax is oblong ovate and moderately robust. The frontal 

 part is considerably contracted, and the frontal margin is produced into a rounded knob. The 

 head is fused with the first thoracic segment. The fifth thoracic segment is distinctly separated 

 from the fourth, and is produced into strong lateral spines, which project beyond the middle 

 of the genital segment. The rostrum is short and very stout, without a tracé of bifurcation. 



The combined length of the abdomen and furca, is rather less than one-third of the 

 total length of the cepkalothorax. from the frontal marmn to the base of the yenital segment 

 The genital segment is broad and slightly swollen below. It is as long as the combined length 

 of the next two segments. The second and fourth segments are of about equal length. The 

 third segment is distinctly shorter than the others. The furcal joints are nearly twice as long 

 as broad, and are as long as the anal segment. 



The antennules are twenty-four-jointed, and extend to the end of the furca. 



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

 Gaidins. 



The exopodite of the first pair of feet is distinctly three-jointed, and the first joint is 

 furnished with one outer-edge spine. 



The second, third, and fourth pairs of feet are similiar in structure to those of Gaidius. 

 The endopodite of the second pair of feet is distinctly two-jointed. The first joint of the basio- 

 podite of the third and fourth pairs of feet is furnished with a number of fine hairs on the 

 inner margin. 



The fifth pair of feet is absent. 



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

 net at Station 203, 1500 metres to the surface. 



The species is easily recognised by its very swollen one-pointed rostrum, and by the 

 complete segmentation of the fourth and fifth thoracic segments. 



Genus Euchirella Giesbrecht, 1888. 



Head with or without a crest. Rostrum one spined or absent. Last thoracic segment 

 rounded or pointed. The endopodite ot the antennae is usually shorter than the exopodite. The 

 first joint of the basiopodite of the fourth pair of svvimming feet of the female, is furnished 

 with one or more spines on the inner margin. 



Eleven species belonging to this genus were found in the plankton collected by the 

 'Siboga', three of which appear to be undescribed. 



1. Eucliirella amoena Giesbrecht. 



Euchirella amoena Giesbrecht, 1888, p. 336. 



Euchirella amoena Giesbrecht, 1893, p. 233, pis. 15 & 36. 



Euchirella amoena Giesbrecht & Schmeil, 1898, p. 36. 



Euchirella amoena Esterly, 1905, p. 155, fig. 21. 



53 



