EITSPIO MBSNILI. 177 



visible tapering anteriorly, but gradually diminishing to the moderately slender posterior 

 end which has four cirri, viz. two somewhat longer and thicker cirri dorsally and two 

 shorter and more slender cirri ventrally. Segments from sixty to eighty. The ligulate 

 branchia occur in all the bristled segments. Superior lamella of the tenth foot is bluntly 

 rounded dorsally, and slopes obliquely to the wide notch inferiorly. Ventral lamella 

 more or less semicircular. Bristles of the upper division extended, with a longer tuft 

 superiorly, all curved backward and winged. The ventral bristles are somewhat shorter, 

 but similarly tapered, and some of the lower present a slight dilatation in the winged 

 region. The type of foot rapidly changes, for at the fourteenth or sooner, a row of hooks 

 appears in the ventral series, with finely tapered short bristles in front, and a few longer 

 bristles inferiorly. The upper lamella gradually diminishes, and still more the inferior, so 

 that the setigerous process becomes prominent, and a group of bristles at the ventral edge of 

 the inferior division is modified, each being curved and flattened, with a probe-tip or hook. 

 The winged hooks have straight shafts which increase in bulk superiorly, then curve 

 backward and slightly dilate before the constriction at the throat. The strong and sharp 

 main fang comes off nearly at a right angle, and the crown has a single sharp spike 

 in lateral view. 



Habitat. — Dredged in 8 fathoms in Bressay Sound, July, 1871. 



Abroad it occurs in Greenland (0. Fabricius, Michaelsen), Spitzbergen, Scandinavia 

 ((Ersted), Finmark (Malmgren). Delle Chiaje describes it as rare at Naples. 



Head somewhat like that of Polydora on a large scale, having a bluntly-bifid median 

 rostrum (prostomium) and a bulging process of the peristomium as a buttress on each 

 side. No eyes are visible in the preparation. The median process passes from the tip of 

 the snout backward, of nearly equal breadth, and ends in a conical papilla. 



Body 2 — 3 inches in length, broad in front, and with scarcely visible tapering 

 anteriorly, whilst it gradually diminishes toward the posterior end, which is moderately 

 slender, the last segment having four cirri, viz. two somewhat longer and thicker cirri 

 dorsally, and two shorter and more slender cirri ventrally, the anus apparently opening 

 between them (Plate XCVIII, fig. 6). The dorsum is somewhat flattened in the broad 

 anterior region, rounded in the narrow posterior part, whilst the ventral surface is 

 flattened, a well-marked median groove passing from the buccal segment to the tail. The 

 bristled segments are distinct and not very numerous, viz. about eighty. The branchiae 

 are continued from front to rear. 



The first foot (Plate XCVI, fig. 7) is comparatively large, with a large and richly 

 ciliated branchia, the broadly lanceolate superior lamella projecting above the level of the 

 dorsum along with the branchia. The tip of the superior lamella is free, whilst the lower 

 margin slopes obliquely to the foot. A tuft of long superior bristles with no traces of 

 wings occurs dorsally, and a comparatively strong series of shorter bristles with curved 

 and finely-tapered tips follows. The ventral lamella is slightly developed as a narrow 

 rounded flap. The setigerous process has a broad fan of bristles similar to the last series. 

 The large and broad branchiae form conspicuous organs on the wide anterior region, 

 and at the tenth foot (Plate XCVI, fig. 7 a) there is no diminution. The superior lamella 

 is bluntly rounded dorsally, and slopes obliquely to the wide notch inferiorly. It is com- 

 paratively narrow. The upper row of bristles is wide, and ends superiorly in the longer 



146 



