552 DR THOMAS SCOTT ON THE 
Genus Machairopus, G. 8. Brady, 1883. 
Machairopus australis, new species. (Pl. VI. figs. 20-28.) 
Female.—Body depressed, anterior portion considerably expanded. Length about 
1*l mm. 
Antennules elongated and slender and composed of nine articulations; the second 
and third joints, which are nearly of equal length, are longer than any of the others ; 
the fifth and sixth are also subequal, but very small, while the end joint is narrow and 
rather longer than the one immediately preceding. Antenne and mouth organs some- 
what similar to those in Machairopus idyoides, Brady. 
First pair of thoracic legs stout; outer ramus much shorter than the inner one; 
while the first joint of the inner ramus is considerably longer than the second, as shown 
by the drawing (fig. 25). The next three pairs-are slender. 
Fifth pair lamelliform; proximal joint small; end joint elongate ovate, widest 
anteriorly, the greatest width equal to rather more than one-third of the length ; both 
lateral margins fringed with minute bristles; this joint is also furnished with three ~ 
apical sete, the innermost being very short, while the other two are moderately 
elongated. 
Caudal rami short, about as long as the last abdominal segment. 
Habitat.—Scotia Bay, South Orkneys; obtained in siftings from some dredged 
material collected in April 1903 ; Station 325, 60° 43’ 42” S., 44° 38’ 33” W. 
Machairopus major, new species. (PI. LV. figs. 14-24.) 
Female.—Resembling the species last described, but larger. Length, 1°5 mm. 
Antennules composed of nine joints; second and third jomts moderately stout, 
subequal in length and longer than any of the others, the two combined being equal to 
the entire length of the following six joints; end joint longer than the preceding one 
(fig. 15). 
Mandibles elongated and narrow, the masticatory end obliquely truncate ; mandible 
pulp small and two-branched. First maxillipeds somewhat slender, but the second 
pair are moderately stout. 
All the four pairs of swimming legs are tolerably stout; in the first pair, the outer 
ramus scarcely reaches to the end of the first joint of the inner ramus; the first and 
second joints of the inner ramus are nearly of equal length. In the next three pairs, 
the inner ramus is rather longer than the outer, and the marginal spines of the outer 
ramus are short and stout. In the fifth pair, the second joint is broadly foliaceous, 
somewhat ovate in outline and widest near the proximal end, the greatest width being 
equal to about half the length; a slender seta springs from a notch near the middle 
of the outer margin, and there are also about four slender and moderately elongated 
setae on the bluntly rounded apex of the joint (fig, 23), 
