Nicholls — Tu'o New Pln'cafoicida. 
193 
members of the genus Phre(itoicu.'<, whereas in Amphiftopiis the female 
is nearly as large as the male or may {‘ven eoiisiilerably exceed that 
in length. 
The body {PI. XXVII, hg. 17) as a whole, appears to be covered 
with tiny liattened setae or scales, which seem to vary in shape 
from a broad triangular to nearly semi-circular, this covering giving 
everywhere to the body and largely to the apt)eiidages, when seen 
ill profile, a serrated margin. This cannot always be made out at 
the extremities of the liml>s, and is less evident on mandibles and 
maxillae, but is clearly visible on flattened surfaces of lips, inner plate 
of maxillipeds, etc. In addition to the scales, the body appears to 
have a scattered granulation, but the fine short setae that furnish 
a thin fur-like covering for the body in other species of PJtreaUncus: 
appear to be entirely absent. 
A transverse corrugation of the surface is well marked, though 
less develo])e<l tlian a])pears, from Geoffrey Rinith’s figures, to be 
the case in P. spinosus and other Tasmanian species. In all of these 
latter, too (including P. <iustraJifi) , Smith notes a serration of the 
antennae which is probaljly due to a retention of scales upon those 
appendages, although this is not stated. In the mainland species of 
Phreafoicus and in A mphiso}}u,^ the scales have apparently dis- 
appeared. 
The body attains its full width at the level of the second 
peraeon segment and maintains a practically uniform thickness to 
the second pleon segment, behind which there is but a very gentle 
tapering to the end of tlie body, so tliat althougli the pleon is (piite 
deep, its depth is nevertheless only II the thickness of the body 
in that region. 
In yet another of the proportions of tlie body, this species is 
probably generalised- — the length of the pleon and telson is rather 
more than four-fiftlis of the length of combined cephaloii and 
peraeon, a condition contributed to partly by tlie unusual shortness of 
the head, but chiefly attributal>le to tlie relative uniformity in the 
length of the body segments. Measured along the mid-dorsal line 
the pleon and telson together have a length etjual to that of the 
seven free peraeon segments. 
The head is strongly convex dorsally from side to side, and in 
profile is almost the quadrant of a circle. The eye is ^er} A^ell 
developed, forming a hcmisiiherical prominence with probably not 
less than one hundred omniatidia. The inferior margin of the 
head is slightly produced postero-laterally, where it touches the 
niaxilliped. From the posterior margin, a well defined groove runs 
upward nearly to the dorsal line. In P. ausiraUs, this is stated to 
actually make a well defined transverse groove; in P. joyneri and P. 
