134 POLYMNIA NEBULOSA. 



middle of the bristled region the longer pale golden bristles have stout striated shafts 

 (Plate CXXVa, fig. 3) of nearly equal diameter, and tapering tips with wings. Many 

 of these seem to have been broken in life, and show modified tips. The striae at the 

 commencement of the wings are oblique. The shorter bristles are more translucent and 

 have either no wings on the free portion or very narrow ones. 



The hooks commence on the segment behind that described as having the 

 triangular fold in a line with the last branchia — that is they occur in the segment 

 behind the branchiae. At first they are in a single row, but by-and-by they form an 

 alternate double row along the centre of the ridges which pass in front from the bases 

 of the setigerous papillae to the edge of the ventral scutes, and behind these almost 

 to the mid-ventral line. With the cessation of the bristles a change ensues, for the 

 hooks are now borne on a prominent lamella — slightly crescentic or scoop-shaped, and 

 placed laterally at the posterior edge of each segment — which still consists of two rings. 

 These lamellae diminish in size posteriorly, becoming minute towards the tip of the 

 tail. On these lamellae the hooks form a close series in a single row. The hooks 

 (Plate CXXVa, fig. 3 a) are distinguished by their elongated basal region, which has 

 a median convexity, then curves upward at the anterior edge, which has a small 

 process for the ligament. A process also occurs on the anterior margin about its middle, 

 a double curve meeting at this point. The large fang is well developed and has only a 

 single tooth above it in lateral view. The posterior margin has a deep incurvation. 

 The hooks vary chiefly in the shape of the basal region. 



The alimentary canal consists of mouth, muscular gullet, which is firm, narrow and 

 dull greyish in colour, with many blood-vessels on its walls. It joins the dilated orange 

 region, with its highly rugose glandular walls and the longitudinal bands of muscles. 

 This terminates in the pale and wide gut which leads to the vent. 



Food. — The muddy sand in the gut was loaded with sponge-spicules, diatoms, 

 Foraminifera and organic particles of various kinds. 



Reproduction. — In June amongst the perivisceral corpuscles were numerous ova 

 which were much larger than the former by one to three diameters, and which varied 

 considerably in size. Each had a zona, granular contents, a clear nucleus, and one or 

 more nucleoli. The ova are developed in the paired, long strap or tongue-shaped ovaries, 

 which arise ventral of the bristle-bundles in the anterior region. They are longest in 

 front, and extend as far forward as the branchiae. The long anterior organs appeared to 

 be empty, only the cilia occurring internally. They soon, however, had ova in their 

 interior and many of the posterior were laden with them. These posterior processes 

 were shorter, broader, and more plume-like. They are attached to the body-wall inside 

 but close to the bristle-bundle, and probably represent those nephridia which transmit 

 the reproductive elements. 



Perivisceral fluid. — This is coloured of a reddish hue and consists of a vast series of 

 ovoid corpuscles filled with yellowish granules, and may possess in addition one or more 

 larger clear circular vesicles, which, however, may be connected with katabolic changes. 

 The corpuscles altered their outline by pressure against each other, and broke up into 

 smaller cells with protoplasmic processes projecting from their surfaces. 



The muscular fibres of the body-wall form a series of strands, both longitudinal and 



