LEIOCHONE OLYPEATA. 321 



Tube free, fragile, cylindrical, composed internally of secretion, and externally of 

 adherent sand-grains, minute fragments of shells, and a few Foraminifera. 



Synonyms. 

 1879. Pr uxilla polaris, Theel. Annel. Nouv.-Zemb., p. 58, figs. 55 — 56. 

 1884. Clymene ,, Levin sen. Nord. Annel., p. 143. 

 1898. Leiochone clypeata, Orlandi. Atti Soc. Ligust. So. nat., vol. ix, p. 18. 

 1900. Glymenella (Axiothella) polaris, Yen-ill. Trans. Conn. Acad. Arts Sc, vol. x, p. 2. 

 1906. Leiochone polaris, Arwidsson. Skand. u. arktisch. Maldan., p. 150, Taf. iv, figs. 118 — 123, 



Taf. ix, figs. 284—287. 

 „ „ clypeata, Bohn. Ann. Sc. nat., ser. 9, t. iii, p. 113 (movements). 



1909. „ „ Lo Bianco. Mitt. Zool. Stat. Neapel, Bd. 19, p. 581. 



1910. ,, polaris, Elwes. Journ. M. B. A., vol. ix, p. 64. 



1913. „ clypeata, Mcintosh. Ann. Nat. Hist., ser. 8, vol. xi, p. 98. 



Habitat. — Dredged in 100 fathoms, St. Magnus Bay, Shetland, by Dr. Gwyn Jeffreys 

 in 1867; common at Torquay (Elwes). 



The anterior end is characterised by the stiff, almost transversely truncate, condition 

 of the cephalic plate, only a very slight inclination downward and forward being noticeable. 

 The surface of the plate is somewhat ovoid, and the rim is slightly developed, being erect 

 all round, and with a shallow excavation in the place of the lateral notch on each side. 

 A short, bluntly-conical, median, frontal process is continuous with the keel — a narrow 

 ridge which passes backward nearly to the posterior border. The nuchal grooves appear 

 to commence near the posterior end of the keel, and diverge a little as they run to the 

 anterior border, debouching on each side of the median frontal process and at a greater 

 distance from each other than usual, indeed, that on the right side cuts off a special section 

 of the rim. Viewed antero-posteriorly the cephalic region is narrower than the second or 

 buccal part, and in lateral view the same condition exists, for the mouth is prominent, 

 three folds characterising the outline behind the median frontal process. 



The body is nearly cylindrical behind the cephalic plate (having been preserved in 

 its tube) with the exception of the slight posterior diminution toward the caudal funnel. 

 Nineteen bristled segments appear to be present and apparently only one unarmed ring 

 posteriorly. The anterior eight are richly supplied with glands, those following, especially 

 the posterior ten, being less so, the wall being more or less translucent. The median ventral 

 streak is faintly indicated; indeed, in the posterior fragment it is not easy to distinguish the 

 dorsal from the ventral surface at first sight, though on subsequent minute inspection, a 

 slight ridge is seen on the ventral aspect of the funnel. The most characteristic feature 

 about the body is the flattened moniliform condition of the last nine bristled segments, which 

 are narrow and vase-shaped, the wide end being posterior. So far as observed no other 

 British Maldanid presents a similar conformation. Behind the foregoing are two rings, 

 the funnel arising with a broad base from the second, and showing a slight constriction 

 before reaching the rim, thus giving the outline of a dice-box to the funnel. Six of the 

 subulate cirri of the funnel are alike and moderately long, the seventh or mid-ventral 

 being a very little longer. Though externally the caudal funnel seems to be long, the 

 anal aperture is in the centre of a shallow distal cup, and has no cone. 



The bristles are in two groups, pale yellow stronger forms nearly straight and with 



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