40 
AUSTRALASIAN ANTARCTIC EXPEDITION. 
It occurs in each case in company with H. spinosa, but in much less numbers. 
For example, whereas at 15-20 fathoms fourteen specimens of H. spinosa were obtained, 
there was only one of H. tuberosa ; at 25 fathoms, in contrast with sixty-five specimens 
of the former, there were only fifteen of the latter. Although Elders originally 
regarded it as a variety of H. spinosa , since it seems nearly always to occur in 
association with it, yet in his later work he pointed out that it is a very distinct species. 
There are one or two features which readily serve to distinguish it at sight from 
H. spinosa : (I) The dorsal chaetae, instead of projecting outwards, have a radiating 
arrangement, as is shown by Elders’s figure ; (2) The absence of pigmentation of the 
upper lip and of the ends of the parapodial lobes (“ acicular processes ”) which is practi¬ 
cally universal in H . spinosa. 
The dorsal surface of the body is free from pigment, so far as my observations 
go, but the lateral longitudinal ridges along the ventral surface are crossed by bars 
of brown, and the posterior feet may be pigmented on their lower faces. The ventral 
surface thus appears dark. 
Ehlers has directed attention to the peculiar transverse “ pads ” which occupy 
the median line of the dorsal surface in each segment, and the “ cushions ” on the 
cirriferous segments in line with the elytrophores, the cirrophores being situated far out 
on the bases of the parapodia. Both these structures occur also in the genus 
Physalidonotus , which Ehlers founded for a Branchiate Polynoid from New Zealand, 
in which the head, however, is “ lepidonotan.” Having had several species of this genus 
under examination recently, it occurred to me that possibly there might be gills here 
also, but on investigation I find that they are absent. 
The dorsal chaetae are “ bearded ” in the same sort of way as are those of 
Physalidonotus . It is evident that Ehlers had before him and has figured a much-worn 
chseta, and that he failed to recognise the true nature of this “ bearding,” for he 
writes, “ ich mag nicht entscheiden, ob diese Faden durch Aufsplitterung des 
Borstenendes entstanden oder epiphvtische Bildungen sind.” 
To me neither of these explanations of the appearance presented by the chaetae is 
the correct one. These long “ Faden ” are similar to those originally figured by Moore 
(1903) for certain species, which he named Lepidonotus branchiferus and L. chitoniformis 
(pp. 405, 409, pi. XXIII, figs. 7 and 10), which really belong to the genus Physalidonotus . 
More recently I have figured the chaetae for P. rugosus and P. paucibrancliiatus (Benham 
1915, pi. XXIX). 
A more detailed account of the dorsal chaetae of H. tuberosa is, therefore, desirable. 
In a perfect unworn chaeta the tip is smooth and rather bluntly pointed. Below this 
smooth region there come three or four pectinated frills* which are produced into long 
* This term was used by A. G. Bourne in his account of the chaetae of Lep. claca. (Trans. Linn. Soc. London., vol. ii, 
1883.) 
