and slightly produced on each side. Tail comparatively short, not attaining 

 half the length of the anterior division, and composed of 5 segments, the 1st 

 (genital) of which is broadly quadrangular in form and provided at the hind 

 corners with 2 juxtaposed setae of unequal length; each of the 2 succeeding 

 segments produced laterally to acute triangular lappets curved backwards; the 

 last 2 segments firmly connected and without any lateral projections. Caudal 

 rami comparatively short, being only slightly longer than they are broad, and 

 somewhat divergent; apical setae not much elongated. Anterior antennae not 

 nearly attaining the length of the cephalic segment, and scarcely at all hinged, 

 being composed of 17 joints, the 1st of which is much the largest, the 9th 

 imperfectly subdivided in the middle; proximal half of the antenna somewhat 

 thickened and clothed in front with scattered rather strong spiniform setae, 

 carrying moreover 8 very slender recurved aesthetasks; penultimate joint with 

 a single such aesthetask behind near the end. Posterior antennae resembling 

 in structure those in the 2 other known species. Oral cone, as in R. pur- 

 purotinctum, very massive and prominent, but not prolonged in any true siphonal 

 tube. Mandibles rather strong, pronouncedly cultriform, and finely denticulated 

 inside the extremity; palp very small. Maxillae, maxillipeds and natatory legs 

 of the usual structure. Last pair of legs extremely small, biarticulate. 



Colour of the living animal not yet ascertained. 



Length of the specimen examined 1.25 mm. 



Remarks. I think I am right in determining the above-described remark- 

 able form as the hitherto unknown male of R. falco Giesbrecht. It may 

 easily be recognised from the other 2 Norwegian species described in Vol. VI 

 by the robust form of the body, by the strongly marked armature of the seg- 

 ments, and by the comparatively short caudal rami. 



Occurrence. The solitary specimen obtained was found in a sample 

 taken at Ris0r from a depth of about 30 fathoms. 



Distribution. Gulf of Naples (Giesbrecht). 



