14 T. V. H01)(;S()\. 



on the first three segments of tlie mesosomc, and in some oases also extend as a band 

 right across each segment. The hxst two segments of the mesosomc in the ' Southern 

 Cross' specimens are as a rule evenly rounded laterally, Itut 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 consideral>le amount of individual variation in this 

 species. Another figure of the male is here given, and this has Iteen drawn from 

 a ' Discovery ' specimen. 



A number of specimens were taken by the ' Di.scovery ' in Winter Ci)uarters, all 

 of them being extracted from sponge dcl)ris. In the roots of these organisms they 

 made their homes. These specimens show a consideraljle range of variation ; a typical 

 example shows the following characteristic features. The ccphalo.some has a sinuous 

 anterior margin with a very small spine in the middle line ; on either side is a swelling 

 which ])ears a distinct .spine at its inner border not far from the middle line. Near the 

 ant<?ro-lateral angle and just in front of the eye is a stout toothed spine ; the ccphalosome 

 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 tlie next; the four following segments progressively 

 increase in length, the fifth and sixth being sul)equal. 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 stnmgly .spinous, especially latenilly, 

 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 proce.s.s. 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 rcpi'esents 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 .setiv. 



The uropoda are large, but not extending beyond tlie telson. The protopodite is 

 stout, and its inner border is produced into a .spinous projection. Tlie endopodite is 

 much broader than the exopodite, and both arc fringed all round with long .setiv;. 

 The entire Ixnly is fringed with long setae, particularly on the cephalo.some and anterior 

 segments. 



Although many of the ' Discovery ' specimens arc, to .some extent at least, 

 covered with a diatomaceous depo.sit, it never roaches that extent which it does in the 

 ' Southern Cro,s3' .specimen.s. 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. 



