
38 RECORDS OF THE S.A, MUSEUM 
near the end. The siphon extends to beyond the base of the second legs. The 
armature of the legs differs from that of serratepes only in having an inner seta 
on the basal segment of the first endopod. The fourth endopod is comparatively 
unarmed, like the other Mediterranean and Australian species, but differs from 
these in the proportions of the segments; the distal segment is as long as the first 
two together, and armed with two small terminal setae, these being the only setae 
on the ramus. The fifth legs are longer than wide, with two terminal and one 
outer marginal setae. The caudal rami are as long as wide and slightly shorter 
than the anal segment. 
The species comes closest to chelifer, but differs in several respects, particu- 
larly in the armature of the fourth endopod. 
It is of interest to note that all those species with reduced armature on the 
fourth endopod are either from the Mediterranean or from Australian waters, 
whereas all the others are from the colder regions of the northern or southern 
oceans and have fully armed fourth endopods. 
Genus Prerorontrus Giesbrecht. 
Giesbrecht, 1895; 1899, pp. 91, 110. 
According to Giesbrecht this genus is characterized by the postero-lateral 
projections from the thoracic and anterior urosome segments; the first thoracic 
segment is fused with the head, with a dorsal crest along its whole length; the 
second antenna is only three-seemented; the fourth leg is without an endopod; 
both rami of the first leg are two-segmented, with reduced setae; the distal seg- 
ments of the third and fourth exopods have only two outer spines; and the fifth 
leg is knob-like. He described a single species, cristatus (1899, p. 36-8, pl. vii, 
fig. 24-39; x, fig. 15-17) and Brady (1910, p. 583, fig. Ixvi) described a second, 
scaber ; the species found here is distinct from both of these. 
In the South Australian species the dorsal crest described for the head seg- 
ment is continued along the second and third thoracic segments; the second an- 
tenna is only indistinctly three-segmented ; the basipod of the fourth leg is com- 
posed of a single segment (as in cristatus. Giesbrecht, op. cit., p. 37); and the 
exopods have three outer spines. It would appear that the segmentation of the 
fourth basipod may be a generic character while the armature of the third and 
fourth exopods is not of generic value. The very short, strongly built siphon 
appears also to be common to all three species of the genus, 
As mentioned above, the genus is wrongly placed in Wilson’s key (1932) 
but it is not surprising that minor errors have crept in when constructing keys 
of such magnitude as those prepared by Dr. Wilson. 
Brady’s description and figures for scaber are sufficient for the identifica- 
tion of his species as a member of the genus, which is well characterized by the 
lateral expansions of the thoracic and anterior urosome segments. His species 
differs notably in the shape of the body. 
Kry To THE FEMALES. 
1. Head segment wider than long ‘2 i Fyn és oe 2 
Head segment longer than wide 2 My scaber Brady 1910. 
2. End segments of third and fourth exopods with two outer spines —_cristatus Giesbrecht 1895. 
End segments of third and fourth exopods with three outer spines barbatus sp. nov. 
PTEROPONTIUS BARBATUS sp. nov. 
Occurrence. IX, 1 female. 
Female, Length 1:02 mm. The head segment is wider than long, with 
the rostral region slightly pronounced and having a small triangular rostrum 
