51 
The antennae, mandibles, maxillae, and first. maxillipedes are nearly similar to those of 
Gaetanus latifrons. 
~The lamella on the basal joint of the second maxilliped, appears to be similar to that 
of Gaetanus latifrons, but the preparation was slightly damaged during dissection, and the apex 
of the lamella was destroyed. 
The exopodite of the first pair of feet is incompletely three-jointed. The division across 
the middle of the first joint, although fairly well defined, does not appear to pass right through. 
The inner margin of the first joint of the basiopodite of the fourth pair of feet, is 
furnished with seven short spines. 
The fifth pair of feet is absent. 
Two specimens were obtained from the plankton collected with the Hensen vertical net 
at Station 276 (750 metres to surface). 
It is only with some hesitation that I describe the above species as new. Both specimens 
although well developed are not quite mature. The narrowly rounded last thoracic segment 
with its short, stout and almost upright spines when seen in lateral view, may help to identify 
it when mixed up with other species of Gaetanus. 
Genus Gaidius Giesbrecht, 1895. 
This genus is distinguished from the other members of the family by the short one- 
pointed rostrum. The exopodite of the first pair of feet in the female is composed of two joints. 
The inner margin of the first joint of the basiopodite of the fourth pair of feet is without 
armature. The male has a well developed prehensile fifth pair of feet. The exopodite of the 
first pair of feet appears to be indistinctly three-jointed in some specimens. 
Two species were obtained from the ‘Siboga’ material. 
1. Gazdius stmzlis (T. Scott). Plate VII, figs. 1—11. 
Euchaeta hessei var. similis T. Scott, 1893 (male only), p. 58, pl. VI, figs. 24, 25. 
Gaidius pungens Giesbrecht, 1895, p. 249, pl. 1, figs. I—4. 
Gaidius pungens Giesbrecht & Schmeil, 1898, p. 32. 
Euchaeta similis Giesbrecht & Schmeil, 1898, p. 52. 
Chiridius tenuispinus Sars, 1900, p. 67, pl. XVIII. 
Chiridius tenuispinus Sars, 1902, p. 30, pl. XVIII. 
Gardius tenuispinus Sars, 1903, p. 162, pl. VI (suppl.), fig. 1. 
Gatdius pungens I. C. Thompson, 1903, p. 17. 
Euchaeta hessez var. similis, 1. C. Thompson, 1903, p. 18. 
Gaidius pungens Wolfenden, 1904, p. 112, pl. IX, fig. 43. 
Gaidius pungens Esterly, 1905, p. 146, fig. I5. 
Gaidius tenuispinus Farran, 1905, p. 33. 
: Gaidius tenurspinus Pearson, 1906, p. 13. 
Gaidius pungens Pearson, 1906, p. 12. 
Gaidius tenuispinus Farran, 1908, p. 32. 
Gaidius tenuispinus van Breemen, 1908, p. 36, fig. 39. 
Gaidius similis appeared to be rather rare in the plankton collected during the traverse 
of the ‘Siboga’, and was only. obtained at the following stations. 
5. 
