SABELLA PENICILLUS. 229 



In lateral view a forward curve of the shaft at the origin of the wings is seen, the 

 tip then gently curving backward to a nearly straight tip. The succeeding tufts are 

 of similar shape — that is, somewhat flattened — but they are longer and stronger, and the 

 edges have distinct serrations (Plate CXXVII, fig. 6 b). The anterior setigerous 

 processes form a somewhat flattened cone, the base ventrally being prolonged into a 

 prominent ridge bearing the hooks, which lie between two raised margins, constituting 

 a narrow flap posteriorly in each segment. Moreover, a distinct papilla occurs on the 

 anterior edge of the tip. 



The setigerous processes of the second region form stiff narrow cones, which 

 project nearly straight outward, the bristles only being visible at the tip. A soft and 

 rather swollen process bearing the hooks lies above their dorsal edges. The bristles 

 form a kind of pillar, narrow at the base and enlarging at the tip to about double the 

 diameter at the base of the wings, which give to the distal end a characteristic lanceolate 

 enlargement, from which the tapering tips slope slightly inward. These differ from the 

 anterior groups in being all of one length, and appear to be ranged round a central 

 papilla. The tips are comparatively short, with somewhat broad wings, which are 

 obliquely striated and serrated along the wide or lower edge. The setigerous processes 

 and bristle-tufts remain of the foregoing structure till near the posterior end, where 

 longer and finer bristles project from the small, modified processes. The bristles are 

 fewer, and of two kinds, viz., a long, slender series (Plate CXXVII, fig. 6h), without 

 visible wings, which have long, gently tapered and slightly curved tips ; and secondly, 

 of a shorter series (Plate CXXVII, fig. 6 t), with rather longer tips than those in front 

 and with striated wings. 



The anterior hooks (Plate CXXVII, fig. 6f) are typical avicularian forms with a 

 marked forward curvature of the crown and a single acute main fang, the free edge 

 of which is minutely serrated throughout the greater part of its extent, leaving little 

 more than a third smooth, and the tip is often slightly turned up. The anterior outline 

 has a wide gulf under the fang and a boldly rounded prow, whilst the posterior outline is 

 convex, and the base is considerably prolonged in this direction and abruptly finished. 

 Curved striae occur at the throat, longitudinal stride in the body, and horizontal striae 

 in the base of the hook. The hooks form a single row. Accompanying each hook in 

 this region is a paddle-shaped or flag-like bristle (Plate CXXVII, fig. 6e), the wings 

 and tip of which are membranous and translucent. The hooks in the middle and 

 posterior regions likewise form a single row, and have almost the same structure as those 

 above mentioned, except that the prolongation of the base posteriorly is less, and no 

 paddle-shaped bristles occur. The posterior hooks, moreover, are considerably less 

 (Plate CXXVII, fig. 6g). 



In a small specimen - x % inch long only three rows of ventral hooks are present, so 

 that the number increases with age. Six brown pigment-specks occur behind the 

 branchiae. The tube of this example is leathery and brownish, with minute mud-particles 

 on its surface and clear granules here and there. Another young form was in a tube 

 projecting from a mass of Alcyonidium parasiticum growing on Sertularia rugosa and 

 Ascidians tossed on shore at St. Andrews. 



A young example procured at the West Sands, after an October storm, measured 



