14 
T. Y. HODGSON. 
on the first three segments of the mesosome, and in some cases also extend as a band 
right across each segment. The last two segments of the mesosome in the ‘ Southern 
Cross ’ specimens are as a rule evenly rounded laterally, but in the more anterior one 
of the two there is sometimes a small incision which cuts off the hinder third. We 
must therefore expect to find a considerable amount of individual variation in this 
species. Another figure of the male is here given, and this has been drawn from 
a ‘ Discovery ’ specimen. 
A number of specimens were taken by the £ Discovery ’ in Winter Quarters, all 
of them being extracted from sponge debris. In the roots of these organisms they 
made their homes. These specimens show a considerable range of variation ; a typical 
example shows the following characteristic features. The cephalosome has a sinuous 
anterior margin with a very small spine in the middle line ; on either side is a swelling 
which bears a distinct spine at its inner border not far from the middle line. Near the 
antero-lateral angle and just in front of the eye is a stout toothed spine ; the cephalosome 
is depressed in the centre, but otherwise almost completely covered with small spines. 
The first segment of the mesosome is a small crescentic structure squeezed in 
between the cephalosome and the next; the four following segments progressively 
increase in length, the fifth and sixth being subequal. The fourth is attached to the 
third by a conspicuous “ waist.” The first is only indistinctly spinous, the second and 
third, and, to a much less extent, the fourth, are strongly spinous, especially laterally, 
and along the posterior border in two segments at least. 
The lateral margin of the fifth segment is invaginated posteriorly, the depression 
being occupied by a button-like process. The sixth segment is divided into two 
halves by a shallow transverse depression, and the posterior border, which is much 
arched, bears a stout tubercle laterally. 
A small crescentic segment overlapping the first abdominal represents the 
seventh. The metasome exhibits five subequal segments with scythe-like epimera. 
The sixth segment is united to an acutely triangular telson, which bears a few setae. 
The uropoda are large, but not extending beyond the telson. The protopodite is 
stout, and its inner border is produced into a spinous projection. The eixlopodite is 
much broader than the exopodite, and both are fringed all round with long setae. 
The entire body is fringed with long setae, particularly on the cephalosome and anterior 
segments. 
Although many of the £ Discovery ’ specimens are, to some extent at least, 
covered with a diatomaceous deposit, it never reaches that extent which it does in the 
£ Southern Cross ’ specimens. It is, however, sufficient to hide small details here and 
there. The variation is great, and in many cases the spinose covering is almost 
entirely absent, but may exist to a very variable extent. In many cases I have been 
unable to detect the three median spines on the cephalon as exist on the figured 
specimen, and the spur at the lateral angle of that structure is sometimes quite 
simple, at times truncated as if broken. 
