£ Prof. jM'Intosh^s JSotes from the 



characteristic lanceolate eulargeraent, from "which the taper- 

 ing 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 com- 

 paratively shortj with somewhat broad wings, which are 

 obliquely striated and serrated along the wide or lower 

 edge. The setigerous processes and bristle-tut'ts remain of 

 the foregoing structure till near the posterior endj where 

 longer aud finer bristles project from the small processes. 

 In these modified processes the bristles are fewer and of two 

 kinds — viz., a long slender series without a visible wing, 

 which have long, gently tapered, and slightly curved tips; 

 and, secondly, a shorter series witii ratlier longer tips than 

 those in front and with striated wings. 



The anterior hooks are typical aviciilarian forms with a 

 marked forward curvature of the crown and a single acute 

 main fang, the free edge of which is minutely serrated 

 througliout the greater part of its extent, leaving little 

 more than a third smooth, and the tip is often slightly 

 turned up. Tiie anterior outline has a wide gulf under the 

 fang aud 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 striaj on 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 

 bristle, the wings and tip of which are membranous and 

 translucent. The hooks in the middle and postei'ior regions 

 likewise form a single row, and have very much the same 

 structure as those above-mentioned, except that the pro- 

 longation of the base posteriorly is less, and no paddle- 

 sha])ed bristles occur. The posterior hooks, moreover, are 

 considerably less. 



In a small specimen, -^^^ of an inch long, only three rows 

 of ventral hooks were 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 Alcyunidium parasiticum 

 growing on Sertularia rugosa and Ascidians tossed on shore 

 at St. Andrews. 



A young example procured on the West Sands, after an 

 October storm, measured after preservation -j^^ of an inch, 

 and it had about 66 segments. The first two bristle-tufts 

 are somewhat short, the third to the Jiixth are long, and 



