
NICHOLLS—COPEPODA FROM SOUTH AUSTRALIA 43 
Scott’s species proximus must. also be excluded from this genus on account 
of the well-developed fourth legs. It is difficult to place this species, which has 
certain affinities with Bradypontius, yet. departs from that genus in several 
particulars. It is clearly a Dyspontiid. 
Thus only two species are left: orbicularis, the type, and australis Wilson 
(1923). The latter was not fully illustrated since only a single specimen was 
obtained. According to Wilson it is distinguished from the type by ‘‘ differences 
in the structural details of the two pairs of antennae, the first maxillae and 
the siphon’’ in addition to which it is twice the size of Boeck’s species. 
The species found here, a single male, is considerably smaller than Boeck’s 
species, and is distinct from both his and Wilson’s. 
ARTOTROGUS LATIFURCATUS Sp. NOV. 
Occurrence. XII, 1 male. 
Male. Length, 1-37 mm.; width 1-24 mm. The body is sub-circular in out- 
line with the caudal rami projecting beyond the posterior body margin. The 
urosome is composed of only three segments, the middle one of which is very 
short and narrower than either first or third. The third and fourth thoracic seg- 
ments are fused, while the fifth is distinct but very short and without epimeral 
expansions; it bears a seta on each side representing the fifth legs. The genital 
seoment is wider than long with two setae on each side of the hinder margin. 
The anal segment widens posteriorly to a greater extent even than in australis. 
he caudal rami are wider than long and bear only terminal setae. 
The first antenna is composed of eleven segments, the fourth and fifth seg- 
ments are very short, the sixth to eighth somewhat longer but shorter than any 
of the remaining segments. A large sensory filament is borne on the terminal 
segment and a great number of thin but much longer filaments are clustered to- 
gether on the second and third segments. The position of these is indicated in 
the figure, but it was difficult to be certain of the total number. It was esti- 
mated that there were about one hundred on the second segment and fifty on 
the third. These filaments easily become detached, when it is found that they 
are swollen basally as shown in the figure. The second antenna is three-seg- 
mented, with the first two segments sub-equal and the third somewhat longer. 
A small exopod is borne distally on the basal segment and is armed with a single 
seta. The siphon is short but reaches to the base of the maxillipeds as in the 
other species. It is bluntly rounded as in orbicularis. The maxillule, maxilla 
and maxilliped are much as in the type species. The swimming legs have the 
following seta formula : 
endopod. exopod. 
pl. 1.2.321. 1.1.323. 
p.2. 1.2.321. 1.1.423. 
3 § tight 1.2.321. 1.1.323. 
P--) left 1.1.321. 1.1.423. 
The outer margin of the head segment (fig. 19, per.) shows a design similar to 
that shown for Entomolepis by Brady (1899) and for Lepeopsyllus by Thomp- 
son and Scott (1903). 
Apart from its much smaller size than either of the two described species 
this differs from orbicularis in the elongate second antenna and in the arma- 
ture of the distal segment of the third endopod. It differs from australis in that 
the siphon does not extend beyond the base of the maxillipds. Other points of 
difference are probably only sexual. : 
