104 AUSTRALASIAN ANTARCTIC EXPEDITION. 



This tentacular membrane, then, has the same topographical relations as the 

 bundle of filamentous tentacles in other genera of the family, and it is unfortunate that, 

 having only this single individual, I am unable to study its structure as fully as it 

 deserves. 



Following the peristomium is the branchiferous segment (fig-,. 12 ', 125, 126). Its 

 dorsal surface is raised up as a transverse fold, which overhangs the peristomium and 

 the posterior portion of the prostomium. It is continued downwards as an ordinary 

 segment, but is without chsetse. This segment carries three pairs of gills, which arise 

 in a transverse line; they are long, simple, sub-cylindrical, and grooved along the 

 posterior margin. The base is more or less expanded, and each terminates on a bluntly 

 rounded extremity. Of the six gills, however, only two remain entire : on the right 

 side the most dorsal, which is 15 mm. long, and on the left side the middle gill, 

 which is 10 mm. long ; the other four are represented by more or less of their basal 

 region. 



The two most dorsal gills are close together near the middle line; the base of 

 each is produced outwards as a rounded ridge, passing obliquely outwards across the 

 dorsum to end at the base of the second notopod. The second gill is immediately external 

 to the first, and the third lies just above and in front of the first notopod. 



There are seventeen pairs of notopods, rather prominent lobes, carrying very long, 

 stout, brown bristles ; the first notopod is on the third segment, which is much com- 

 pressed between its neighbours (this is perhaps due in part to the contraction of the 

 body) ; it is smaller than the rest, and carries fewer and shorter bristles ; the second is 

 longer, the following increase in size, and the full development of the foot is attained at 

 the sixth or seventh. 



The bristles, of which there is a considerable number in each notopod, arranged 

 in a double or triple vertical series, are brownish in colour ; each is long, thick at the 

 base, slightly curved, and produced into a very fine point ; there is single flange on the 

 convex border.* 



The uncinigerous neuropods commence below the fourth notopod on the sixth 

 body segment ; they are definite, wing-like, mobile organs, increasing in prominence pos- 

 teriorly. In the thorax the neuropod has a long, vertical, uncinigerous margin, 

 equalling in height that of the organ itself, but in the abdomen the neuropod is very 

 convex superiorly, and has a short uncinigerous margin directed somewhat downwards 

 (fig. 129). 



The uncini are uniserial throughout the body, and number about eighty in 

 the anterior feet. 



The uncinus (figs. 130, 131) has two rows of four nearly equal teeth, springing 

 from a short, broad base, which is produced info a rounded lobe beyond the fourth 



Treated as I treated the ehsetae of Phyllocomu* I find that the two literal flanges are not present- 



