14 T. V. 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 endopodite 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. 



