POLYCHjETA BENHAM. 106 



tooth, which is slightly smaller than the others; the base has also a small lobe on its 

 lower edge below the first tooth. The uncini are similar throughout, but on the 

 thorax are larger than on the abdomen. 



Locality. 



Commonwealth Bay, Station 10, 325 fathoms. 



Remarks. The worm agrees fairly well with Malmgren's diagnosis of Ramyllia, 

 from which it differs in three noticeable features (!.) the form of the pros- 

 tomium ; (2) the presence of a folded membrane in place of filamentous 

 tentacles ; and (3) the form of the uncinus. It bears no resemblance to the 

 only known Antarctic Ampharetid Samytha (?) speculatrix Ehlers (1913, 

 p. 554). Consequently, a new genus is necessary, which may be defined as 

 follows : " Ampharetids with a trilobed prostominal flap; tentacles repre- 

 sented by an invaginable membrane; three pairs of cylindrical gills on the 

 second segment ; seventeen pairs of notopods ; uncinus with four paired 

 sub-equal teeth on a broad base. 



Family CAPITELLIM. 

 Genus ISOMASTUS Gravier. 

 ISOMASTUS PERARM ATUS Gravier. 

 Gravier (1911), p. 113, pi. VIII, figs. 88-93; pi. IX, figs. 94-108. 



Four specimens of this, the only Capiiellid known from the antarctic, were 

 gathered, amongst which a well preserved male measures 42 mm. in length by 2 mm. in 

 diameter anteriorly ; it contains fifty-two segments following the head. There is also 

 a female in the collection. 



Locality. 



Boat Harbour, Commonwealth Bay, 3| f athoms ( muddy bottom). 



Distribution. Admiralty Bay, South Shetlands, Petermann (Gravier). 



Family MALDANIM. 



Genus RHODINE Holmgren. 



RHODINE INTERMEDIA Anvidsson. 



Ardwidsson(1911), p. 11, pi. I, figs. 5-11; pi. II, figs. 39-41. 

 R. loveni Willey (1902), p. 276, pi. XLVI, figs. 3-5. 

 R. antarctica Gravier ( 1906), p. 39, pi. IV, figs. 33-37. 



R. loveni Gravier (1911), p. 125, pi. IX, figs. 110-112; pi. X, fig. 114; pi. XI, 

 fig. 133. 



A single imperfect specimen, consisting of the head, followed by thirteen 

 chsetigerous segments, and another portion consisting of six posterior segments, measure 

 in all 35 mm. by 1 mm. in diameter. 



83892-0 



