218 
One species, apparently undescribed, but agreeing with Brapy’s definition of the genus, 
was obtained from the plankton collected by the ‘Siboga’ in the Malay Archipelago. 
1. Pseudothalestris sarst nov. sp. Plate LXIII, figs. 1—7. 
Female — length .68 mm. 
Seen from the side, the body appears short and moderately robust. The cephalic segment 
is large and exceeds the combined length of the thoracic segments. The rostrum is very short 
and is triangular in shape. 
The abdomen is composed of four segments. The genital segment is longer than the 
combined length of the next three segments. The anal segment is much shorter than the other 
segments. The furcal joints are shorter than the anal segment. Each joint is one and a half 
times broader than long (Plate LXIII, fig. 7). 
The antennules are comparatively short and six-jointed. The fifth joint is shorter than 
any of the others. 
The antennae, mandibles, maxillae and maxillipedes are similar to those of Pseudothalestris 
embricata Brady. . 
The exopodite of the first pair of feet is short and is distinctly two-jointed. The joints 
are sub-equal in length. The endopodite is composed of three joints and is equal to two and 
a half times the length of the exopodite. The first joint is very long. The second and third 
joints are exceedingly short. The apex of the third joint is furnished with one long and one 
very short claw, and a small seta (Plate LXIII, fig. 5). 
The second, third and fourth pairs of feet are similar to those of Pseudothalestris 
embricata Brady. 
The fifth pair of feet is comparatively large. The proximal joint is greatly expanded. 
The apex is armed with five moderately strong spines of unequal.length and four small setae. 
The distal joint is small and is somewhat quadrangular in outline. It is furnished with one 
outer marginal spine, one inner marginal spine, and one apical spine. The distal end of the 
inner margin has also two short setae (Plate LXIII, fig. 6). 
Male unknown. 
This species resembles Pseudothalestris major T. and A. Scott (1895), in general 
appearance, but it can readily be distinguished from it or any of the other members of the 
genus by the proportional length of the joints of the antennules, and by the shape and armature 
of the fifth pair of feet. Sars, ‘Crustacea of Norway’ Vol. V, p. 143, regards Pseudothalestres 
major to be identical with Westwoodia minuta Claus (1863). This view cannot very well be upheld 
because Cxiaus in his generic description of Westwoodia defines the exopodite of the first pair of 
feet to be short and one-jointed. Pseudothalestris major has the exopodite distinctly two-jointed. 
The shape and armature of the fifth pair of feet illustrated by Sars as that of the female of 
lVestwoodia minuta Claus, is quite different from the figure of the same pair of Pseudothalestris 
major given by T. and A. Scorr in the ‘Annals and Magazine of Natural History, Ser. 6, 
Vol. XV, January 1895. Sars states that Westwoodia minuta Claus, has six-jointed antennules: 
: 218 
