47 28 Proceedings of the Royal Irish Academy^ 



Further research, however, may show that the two species are identical. As 

 stated above, the Streptosyllis varians of de Saint-Joseph seems to be different 

 from that of Webster and Benedict. 



Habitat. — Bat.t.vxaktt.t, Harbour — Bottom tow-net, in 2-6 fms. Bofds 



Harbour — Taken on two occasions in the tow-net, soundings 



1-4 fms. 



Streptosyllis bidentata sp. n. 

 PL III, figs 4a-f. 



A number of fragmentary specimens of this new species were dredged in 

 24 fathoms in Clew Bay, on a bottom of sand and shells, associated with a 

 very peculiar microfauna. 



The longest specimen is 2 - 5 mm., composed of 23 segments. It is com- 

 plete posteriorly, except for the fact that the anal segment is damaged. This 

 specimen is an immature female, with developing eggs in the body-cavity. 

 Another specimen, with the posterior part missing, had 31 setigerous segments. 



The body is widest in the region of the proventriculus, tapering very 

 slightly towards the head, much more so towards the tail. 



Most of the appendages are missing, but those which remain are smooth 

 and cylindrical, with no trace of moniliform articulations. 



The head (fig. 4a) is broad, and the width greatly exceeds the length. 

 There are four large reddish-brown eyes, with lenses. The appendages of 

 the head are missing, but the base of the medium tentacle is seen between 

 the ant«rior pair of eyes. The palps lie on the ventral surface (fig. 4b), and 

 are invisible from above- Their basal portions are closely fused with the 

 ventral side of the head, and they terminate in slender papillae. Between 

 the head and the buccal segment are the ciliated nuchal organs. The buccal 

 segment is quite distinct from the head, and bears two pairs of smooth cirri. 

 There is a patch of cilia on the dorsum above each foot (fig. 4a). The 

 anal region in all the specimens is more or less imperfect ; but there seem to 

 be a pair of short lateral cirri and a short slender median cirrus. The feet 

 are prominent, and the anterior six segments differ from those which succeed 

 them. The first setigerous segment contains a simple dorsal seta, 8 compound 

 setae, of which 7 have short tips and one a long tip, and a slender spine 

 with a swollen tip. The 2nd to 6th feet have each a simple dorsal seta, 

 5-8 compound setae, of which 3-6 have short tips and 2 long tips, and one or 

 two very thick spines with large swollen tips. Apart from these differences 

 in detail, the setae of the 6 anterior segments are similar, and those of the 

 third segment may be described as typical of the others. 



7)-ip setigerous lobe (fig. 4r) is blunt, and is supported by one or two very 



