ENTOMOSTRACA OF THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 559 
two at the apex ; the apical sete are slender, but the others are tolerably stout. Caudal 
rami short. 
Habitat.—Scotia Bay, South Orkneys; collected in June 1903; Station 325, 
60° 43’ 42” 8., 44° 38’ 33” W. 
Genus Pseudothalestris, G. 8. Brady, 1883. 
Pseudothalestris intermedia, new species. (Pl. IX. figs. 1-4; Pl. XII. figs. 27-29.) 
Female.—The female of this species is small, measuring only about 0°4 mm. 
(about <5 of an inch), and has a general likeness to Pseudothalestris pygmxa, Scott. 
The antennules are composed of seven joints; the second joint is tolerably large, 
but the next three are each shorter than the one that precedes it; the two end joints 
are small, and together are only about equal to the third, as shown in the formula, 
which gives approximately the proportional lengths of the various joints : 
Numbers of the joints 1 2 3 4 5 6 7 
Proportional lengths 7 8 7 3 2 3 4 
In the first pair of thoracic legs, the two-jointed outer ramus is tolerably short, and 
the seta on the inner margin of the first joint of the inner ramus springs from slightly 
below the middle of the joint, instead of from near the proximal end. 
The fifth pair of thoracic legs are small; the basal joint is moderately broad, and 
the produced inner portion is of a triangular form, and furnished with three setz on the 
lower half of the inner margin, and with two on the outer margin near the apex: a 
distinct space also separates these two from the others; the second joint is small, and 
bears three setze on the outer margin, one on the inner margin, and one at the apex— 
these setze are all tolerably elongated, as shown in the drawing (fig. 5, Pl. XII.). 
Male.—In the second pair of thoracic legs of the male, the second joint of the 
inner ramus is provided with five setae—two on the inner margin, one near the proximal 
end of the outer margin, and two at the apex; and the innermost of the two apical 
setee forms a stout and claw-like appendage, but the other four sete mentioned are 
tolerably slender (see figs. 3 and 3a, PI. [X.). 
Fifth pair small; the inner portion of the basal joint moderately produced, an 
furnished with a short, stout seta on the inner margin, and with two at the apex, the 
‘outer being considerably smaller than the other (see fig. 4, Pl. IX.). 
Habitat.—Scotia Bay, South Orkneys; collected in June 1903; Station 325, 
Mes 42” §., 44° 38’ 33” W. 
Remarks.—The species described above differs from Pseudothalestris pygmea, 
Scott, and Westwoodia minuta, Claus (both of which it resembles to some extent), in 
the structure of the female antennules, in the armature of the inner ramus of the second 
pair of thoracic legs in the male, and in the form of the male and female fifth pair. 
There are also one or two other points of difference, but those referred to appear to be 
the most important. 
