Clare Island Survey — Archiannelida and Pohjchaeta. 47 23 



Pionosyllis serrata sp n. 

 Pis. III-IV, figs 5A-K. 



The type of this new species was found on the shore of Blacksod Bay. A 

 number of other specimens were also obtained in Bonn and Ballynakill 

 Harbours. 



The worms are small, 2 - 5-3 mm. in length, consisting of 27 setigerous 

 segments. The preserved specimens are colourless. The parapodia project 

 for a considerable distance, and in length almost equal the width of the 

 trunk. The total width, not counting the setae, is '65 mm. at the broadest 

 part, which is in the 10th segment. Behind this the body gradually grows 

 narrower. 



The head (fig. 5a) is rounded in front, straight behind. It has six eyes. 

 The anterior pair are mere pigment spots, lying inside the bases of the 

 lateral antennae. The middle pair are large and have the lenses directed 

 forward. The posterior pair are nearer together and have the lenses pointing 

 backwards. The median antenna rises from the dorsal side of the head, just 

 in front of the eyes. The lateral antennae are shorter, and arise from the front 

 margin of the head. The palps are placed ventrally and fused together at 

 the base. 



The buccal segment bears a pair of tentacular cirri on each side, the 

 dorsal pair being the longer. The antennae and cirri, as well as all the dorsal 

 cirri, are smooth and cylindrical, with no trace of the moniliform condition. 

 They are jointed at the base. The buccal segment is not visible on the dorsal 

 surface, being covered by the first setigerous segment. The dorsal cirri of 

 the first setigerous segment are the longest appendages of the whole body, 

 being "5 mm. in length. The setigerous lobes of this segment project forwards 

 alongside the head. In the anterior and posterior segments the ventral cirri 

 project beyond the setigerous lobes, but in the middle feet they are equal in 

 length or slightly shorter. 



The anal segment (fig. 5b) is rounded, without a median papilla, and 

 bears two slender cylindrical cirri. 



The anterior parapodia are provided with two aciculae and a fan-shaped 

 series of 14 setae. The typical parapodium (fig. 5d) has a bluntly pointed 

 setigerous lobe bearing a small dorsal papilla at the tip, so that it seems slightly 

 bifid when seen from above. The ventral cirrus is broad and subulate. 



There is a fan-shaped series of 16 setae with the tips facing upwards. The 

 dorsal setae differ both in length and minute structure from the ventral 

 setae. The tips of the shafts are swollen and bevelled, with a series of 



