POLYCH.ETA. — BENHAM. 209 



Family STAURONEREID^. 



Genus Stauronereis.i Verrill. 



Stauronereis australiensis, M'Intosh. 



(Plate xli., figs. 58-66.) 



StaurocepJmlus australiensis, M'Intosh, Ohall. Rep., Zool., 

 xii., 1885, p. 232. Id., Treadwell, Bull. U.S. Fish. 

 Comm., xxiii., 3, 1906, p. 1173. 



A single entire individual, which 1 believe belongs to this 

 species, which M'Intosh founded on a posterior fragment. 



The worm is nearly white, and is probably pink in life. 

 It measiues 75 nun. in length, with a diameter of 5 mm. 

 over the body, and 10 mm. over the parapodia. It con- 

 sists of a head with 145 cha^tigerous segments, whose length 

 is about one-eighth the width of the body in the anterior half, 

 and one-fifth posteriorly. The body is slightly wider anter- 

 iorly, tapering slowly backwards. The dorsal surface is 

 convex ; the ventral flat with a median furrow. 



The semicircular prostomimn is of small size, its base 

 being about a quarter the width of the jDeristomium (PI. 

 xH., fig. 58). 



The tentacles are moniliform, with 9 rings, terminally 

 rounded, the last ring being longer than the others. They 

 are relatively thick and short, scarcely reaching beyond the 

 lateral margin of the body ; or when pressed back, to the 

 posterior margin of the first chsetigerous. 



There is a pair of downwardly directed palps, not monili- 

 form, but the apex is constricted from the rest ; the rest is 

 smooth, but a good deal contracted so that irregular furrows 

 cross it. It is only a little longer than the tentacle, but a 

 good deal stouter (PI. xli., fig. 60). 



There are two pairs of eyes, the anterior pair, the larger, lie 

 at the side of the prostomium, in front of the base of the 

 tentacles ; the hinder pair behind the tentacles, nearer to 

 the midline. They lie below the edge of the peristomial 

 margin, which overlaps the prostomium (PI. xli., fig. 59). 

 When this hood is lifted backwards the transverse slit- 

 like openings to the nuchal organs are displayed, and in the 

 middle line is seen the small rounded connection between 

 the prostomium and peristomium. 



1. Ehlers points out why this name must take the place of Grube's 

 Stanrocephalus and Anisoreras (Die Polychseten d. magellan u. chilen. 

 Strandes, 1901, p. 146). 



