172 DISCOVERY REPORTS 



Genus Idanthyrsus, Kinberg 



Opercular peduncles long, more or less separate. Two rows of paleae. Dorsal hooks 

 present. A pair of slender palps and usually a median tentacle. Numerous filiform 

 tentacles on the ventral face of the peduncles. First and second segments with a bundle 

 of capillary bristles. Three biramous parathoracic segments. Cirriform dorsal branchiae. 

 In the abdominal region the dorsal ramus carries small uncini and the ventral capillary 

 bristles. A smooth, achaetous cauda. 



Idanthyrsus armatus, Kinberg. 



Pallasia seximgula, Ehlers, 1897, p. 125, pi. viii, figs. 194-202. 

 Idanthyrstts armatus, Johansson, 1927, p. 90; Monro, 1930, p. 177, fig. 73. 



Occurrence. St. WS 216 (numerous); WS 223 (10); WS 243 (4, with tubes); WS 244 (i); 

 WS 755 (3); WS 785 (3); WS 788 (i); WS 796 (10); WS 797 (4); WS 801 (6); WS 805 (4); WS 807 

 (3); WS 813 (6); WS 814 (2); WS 825 (2); WS 851 (i); WS 866 (2); WS 867 (5). 



Specific characters. Two rows of paleae. The opercular peduncles are completely 

 separate. The opercular crown is very obliquely truncated. The paleae are golden and 

 the outer row consists of long pinnate paleae of a characteristic appearance [vide 

 Monro, loc. cit., fig. 73). The inner paleae are long smooth hooks with narrow transverse 

 striae. There are usually three (in young examples two) pairs of dorsal hooks. A median 

 tentacle is present. Gills are absent from the last few chaetigers only. 



Remarks. This species is very common in the Falkland Island area. It appears to 

 extend a long way up the west coast of America. I have myself recorded it from 

 Gorgona Island and Johansson is very doubtful whether Chamberlin's /. ornamentatus 

 from California is separable. 



Family AMPHICTENIDAE 

 Genus Pectinaria, Lamarck 

 Tentacular membrane with a denticulated edge. Dorsal border smooth or crenate. 

 Scapha separated from the abdomen by a constriction. No eyes on the scapha. Two 

 pairs of branchiae. A single pair of cement glands. Three pairs of nephridia, the first 

 pair markedly longer than the rest. Dorsal bristles of two kinds. Uncini pectiniform 

 with teeth of different sizes. 



Pectinaria ehlersi, Hessle. 



Pectinaria belgica, Ehlers, fiec Pallas, 1901, p. 204. 



Pectinaria ehlersi, Hessle, 1917, p. 77, pi. i, fig. i, text fig. 3 a-e. 



Pectinaria {Cistenides) ehlersi, Nilsson, 1928, p. 33, fig. 10 a, b. 



Occurrence. St. WS 212 (i); WS 236 (i). 



Specific characters. Tentacular membrane with 20-30 processes. Up to about 15 

 paleae on each side. Seventeen chaetigers, of which 13 (from the 4th to the i6th) are 

 uncinigerous. Dorsal bristles of two kinds — straight, narrowly bordered bristles with 

 delicately hirsute ends ; and bristles with curved tips strongly denticulated on the con- 

 cave side. In profile the uncini have four large teeth above the finely denticulated basal 



