47 24 Proceedings of the Royal Irish Academy. 



conspicuous spines, in the dorsal setae the terminal pieces (fig. 5e, b) are 

 long and bifid at the tip, with four or five long slender teeth near the 

 proximal end. In this latter respect they greatly resemble the setae of the 

 Hesionid Gastalia fusca (Johnston). The upper tooth of the tip is boldly 

 hooked, the lower tooth almost vertical. The ventral setae (fig. 5e, c) are 

 short, not bifid at the tip, but simply hooked, and the margin is smooth or 

 very faintly and indistinctly toothed. Of the 16 setae in each foot, 5-7 of 

 the dorsal ones are bifid, the remainder being simple. The intermediate 

 setae show signs of transition as regards both the bifid tips and the serrate 

 margin. 



There is a single stout aciculum in each foot, except in the anterior 

 segment, where there are two, rapidly tapering towards the end, and 

 terminating in a bulbous tip (fig. 5e, a ). 



In the six posterior segments there is a single long very slender simple 

 seta in the dorsal part of the foot. 



The proboscis (fig. 5c) is very short and broad, '21 mm. in length, 

 occupying only two segments of the body. It is brown in colour with a 

 smoothly rounded anterior margin, and with a large tooth on the dorsal side 

 near the front. The proventriculus occupies three segments. It is "33 mm. 

 in length, with 20 rows of glands. Mature specimens containing eggs and 

 sperm, but without capillary setae, were found in September, in Bofin 

 Harbour. 



This species is very closely related to Pionosyllis pv.lligera (Krohn). The 

 latter, which has been examined by Krohn, Claparede, Viguier, de Saint-Joseph, 

 and Pierantoni, has not yet been satisfactorily described and figured ; but it 

 appears to differ from the present form in the following points : — 



(1) The buccal segment is quite distinct, and is visible on the dorsal side, 

 whereas in P. serrata it is covered by the first setigerous segment. (2) The 

 proventriculus in P. pulligera occupies two segments, in P. sermta three 

 segments. (3) The setae are very different in appearance. The spine also 

 does not resemble the characteristic figure given by Viguier (1884, PI. V., 

 fig. 53). (4) In P. pulligera the lateral antennae are relatively much shorter 

 than in P. serrata. 



Habitat. — Blacksod Bay — A single specimen on the shore. Bofin 

 Harbour — Taken on three occasions, in 1-4 fms. Ballyna- 

 kill Harbour — Taken on two occasions, in 2-8 fms. 1§ miles 

 off Cleggan Head, in mid-water tow-net at 7 fms. 5 miles 

 X.W. by N. of Inishturk, in surface tow-net at night. 



