278 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 15 



gradually increase in size in posterior thoracic and anterior abdominal 

 segments. The prostomium is equitriangular in shape and has no eyes. 

 The everted proboscis is voluminous and multilobed at its distal everted 

 end. 



In the thorax the neuropodial postsetal lobe is triangular in the first 

 ten segments; thereafter it is divided so that a smaller second lobe is 

 present below the larger one but both are postsetal (in the specimen 

 from New South Wales, the divided condition is present from the eighth 

 setigerous segment). In the last two thoracic segments the ventral lobe 

 resembles a ventral cirrus. These lobes are abruptly absent thereafter. 

 There are no interramal cirri, no subpodial fringe and no other cirri 

 resembling ventral cirri. 



In middle abdominal segments the branchiae are large at the base 

 and conspicuously fimbriated along their sides for the basal third ; more 

 distally they are slender and terminate in attenuate tips. Branchial bases 

 are widely separated middorsally. In posterior abdominal segments the 

 neuropodial superior lobe is long and triangular, the inferior one is much 

 shorter but also triangular. The neuropodium is supported by 3 or 4 

 slender pale acicula in a close, fully embedded fascicle. The correspond- 

 ing notopodia have a long, foliaceous postsetal lobe exceeded in length 

 by the accompanying erect, lanceolate branchiae. 



In ovigerous individuals large ova are present from the ninth ab- 

 dominal segment and continue back through at least 46 segments; on 

 these individuals the glandular pads are visible from the thirteenth or 

 fourteenth abdominal segment. 



The largest individual from Yorke Peninsula agrees with the type 

 specimens except that branchiae are not present before the fifteenth seti- 

 gerous segment and the prostomium is proportionately longer and great- 

 ly attenuated at its tip. Another one from Encounter Bay has a similar 

 pointed prostomium and branchiae are present from the ninth segment. 

 Still another from the same place has 19 thoracic segments, the twentieth 

 being transitional; branchiae are first present from segment 15 and the 

 prostomium is short and triangular. Posterior thoracic neuropodial lobes 

 are elongate triangular and only the last four segments have a small 

 accessory ventral lobe. Two posterior ends from South Australia have a 

 pygidial ring provided with a pair of long cirriform filaments attached 

 dorsolaterally. 



Haploscoloplos bifurcatus differs from other species of the genus (see 

 also key above) in that posterior thoracic neuropodia have divided post- 

 setal lobes (hence the specific name) ; branchiae are present in posterior 

 thoracic segments; the transition from thorax to abdomen is abrupt and 

 about at segment 21/22. 



