ENTOMOSTRACA OF THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 568 
Genus Phyllopodopsyllus, Scott, 1896. 
Phyllopodopsyllus mossmani, new species. (Pl. V. figs. 1-14.) 
Female.—In its general appearance, the female of this species resembles that of 
Phyllopodopsyllus bradyi; there are, however, a few small but obvious differences 
which, though they may not be of so much importance as to separate this form 
generically, are yet sufficient to exclude it from any species hitherto described. The 
leneth of the specimen represented by the drawing on Pl. V. is 0°71 mm. 
Antennules nine-jointed, like those of the type species; the first joint is large and 
about equal to the combined lengths of the next three joints: these three joints do not 
differ much in size, but the third and fourth are each rather smaller than the preceding 
joint ; the seventh and eighth are smaller than any of the others, and are together only 
equal to about half the length of the end joint; the second jomt wants the spur-like 
process with which that joint is armed in both the type species: Phyllopodopsyllus 
brady: and the Phyllopodopsyllus furcifer described by G. O. Sars (fig. 2). The 
antennz are similar to those of the type species, as are also the maxille, but the 
mandibles are rather stouter, and the two branches of the mandible-palp do not differ 
so much in length, the lower branch being in the type species distinctly smaller than 
the other. The two pairs of maxillipeds are similar to those in the type species (fig. 4). 
The swimming legs have the inner rami all two-jointed and the outer rami three- 
jointed ; in the first pair the inner ramus is fully one and a half times longer than 
the outer one, the first joint being considerably longer than the entire outer ramus ; 
the end joint, which is much smaller than the first, is armed witb a stout apical claw 
and an elongated seta. In the second and third pairs, the inner ramus, which scarcely 
reaches the end of the second joint of the outer, has the joints subequal. In the fourth 
pair, the inner ramus is very small, being shorter than the first joint of the outer one 
(see figs. 7-10). j 
The fifth pair form each a large foliaceous plate, somewhat oval in outline ; its length 
is equal to about twice the width, its distal end is rounded but the inner portion 
slightly produced, and it is furnished with several small setze round the inner margin 
and apex (fig. 11). 
The caudal rami are about equal in length to the last segment of the abdomen, and 
the principal tail seta, which is somewhat dilated at the base, is long and slender. 
Mule.—The male is smaller than the female, and measures only about 0°55 mm. in 
length. ‘he structure of the antennules is modified so that they form effective grasp- 
ing organs. In the second pair of swimming feet the inner rami are proportionally 
rather longer than in the female. 
The fifth pair are small and normal in structure (fig. 12). The caudal rami are 
more slender than in the female, and the principal tail seta is not only elongated but 
is also somewhat stout and spiniform. 
With these exceptions, the structure of the male and female is somewhat similar. 
