PIONOSYLLIS (SYLLIS) HYALINA. 167 



long, and bifid at the tip, the edge below being boldly spinous. The ventral cirrus is 

 somewhat lanceolate and scarcely reaches the tip of the setigerons process. 



In the posterior segments the bristles are more slender, with short terminal pieces 

 (about as broad as long— Grube) . 



Synonyms. 



1843. Syllis tigrina, Rathke. Nova Acta Leop. -Carol., xx, p. 165 (?). 

 1852. „ fissipara, Krohn. Arch. f. JSTaturg., Bd. xviii, p. 68. 



1863. „ hyalina, Grube. Ibid., xxix, p. 45, Taf. iv, f. 8. 



1864. „ pellucida, Elilers. Borstenw., I, p. 239, Taf. x, f. 6—11. 

 „ „ simillima, Claparede. Grlanures, p. 77, pi. v, f. 4. 



1867. „ borealis, Malmgren. Annul. Polych., p. 42, pi. vi, f. 42 (?). 



1868. „ simillima, Claparede. Annel. Nap., p. 199, pi. xii, f. 5. 



1874. „ macrocola, Marenzeller. Sitzb. k. Akad. Wien, Bd. lxix, 1 Abth., sep. abd., p. 37, 



Taf. in, f. 3. 



1875. „ hyalina, idem. Ibid., Bd. lxxi, p. 22 (sep. abd.). 



1879. Typosyllis (Syllis) hyalina, Langerlians. Zeitsch. f. w. Zool., Bd. xxxii, p. 535. 



1905. Syllis hyalina ( = fissipara, Krohn, etc.), Graeffe. Arbeit. Zool. Stat. Triest, XV, p. 323. 



Habitat. — Millbay Channel, Plymouth Sound (Dr. Allen). 



Lussin Grande, Neresino, Crivizza, in the Adriatic (Grube) . Quarnero, Adriatic 

 (Ehlers). Common in 20 — 30 fathoms off Madeira and also between tide -marks 

 (Langerhans) . Adriatic (Marenzeller). 



Head with the structure of Syllis ; two long palpi ; eyes comparatively small ; anterior 

 pair the wider apart. 



Body of about 100 segments, the anterior end being slightly tapered, and gradually 

 increasing to a little behind the anterior third, this region being of a yellowish brown 

 colour, and each segment being banded with brown, which anteriorly is in the form of 

 a double band — a longer at the segment-junction, and a shorter immediately in front. 

 The succeeding region is uniformly thicker, and has a pinkish or salmon colour, a darker 

 stripe marking the segment-junctions. Pharynx (proboscis) long, with a large dorsal 

 tooth and twelve soft papillas in front. The proventriculus has thirty or more rows of dots 

 and is reddish. 



In this species the dorsal longitudinal muscles have a different character from those 

 of Syllis annillarls, which form a continuous and massive band on each side. In 

 S. hyalina they are considerably thinner, and are cut into a larger upper band and a 

 smaller inferior division on each side (Fig. 54), the former stretching to a point a little 

 above the origin of the dorsal cirrus, and the latter terminating at the base of the spine. 

 The ventral longitudinal muscles are also somewhat thin, and show a marked differentiation 

 on each side of the muscular slip from the base of the spine. 



The foot (Plate LXX, fig. 24) has a dorsal cirrus of 22 — 23 articulations ; 

 setigerous region forms a short cone, with the edge below the apex split, the longer 

 margin being inferior. Ventral cirrus lanceolate, and does not reach the tip of the 

 setigerous region. Bristles (Plate LXXVIII, fig. 9) translucent, with curved shafts, 

 dilated and bevelled ends, which show traces of serrations on the convex border. The 



