Gatty Marine Lahoratory^ St. Andreios. 125 



and it can be retracted so as to leave only the margin of the 

 buccal segment in front. At its base on each side are two 

 groups of brownish grains marking the nuchal organs. The 

 second or buccal segment is biannulate, devoid of bristles, 

 and the mouth opens on its ventral surface as a proportion- 

 ally large aperture. The body is a little tapered in front 

 of the larger anterior region, remaining of nearly equal 

 diameter for a considerable distance, and then tapering 

 gradually to the tail, which ends iu a slightly upturned vent 

 with two papillse beneath. 



The anterior region comprehends the buccal and eleven 

 bristled segments, each of which is two-ringed and more or 

 less tessellated on the surface. The succeeding region 

 differs in appearance, having, as a rule, longer segments 

 with prominent tori for the hooks. Each segment anteriorly 

 shows a double median dorsal elevation and two long lateral 

 ridges which pass to the ventral surface. Posteriorh'^, again, 

 the four tori are more nearly equal in size and more widely 

 separated, two being dorsal and two ventro-lateral in 

 position, the two median elevations of the dorsum having 

 disappeared; and toward the tip of the tail the four 

 prominent tori give the body a quadrangular aspect on 

 section. The anterior segments have a deep transverse 

 furrow which divides them into two halves. Laterally this 

 furrow bends backward at each bristlc-tuft — making, as it 

 were, a small setigerous process, — the bristles issuing quite at 

 its posterior border. The two upper tufts of bristles are 

 wholly dorsal, and thus those of opposite sides approach 

 each other more nearly than the ventral. The bristles have 

 simple straight shafts, which begin to taper at the slight 

 bend marking the commencement of the somewhat narrow 

 wing. Though the tip is acute yet the whole bristle is 

 elastic and strong. De St. Joseph slates that their bases 

 rest on a large gland. 



At the twelfth bristled segment a double process carrying 

 hooks appears in the mid-dorsal lino, and this continues to 

 the twentieth segment of the region without much change. 

 Thereafter the two processes have a tendency to disappear, 

 so that at the thirtieth segment no trace occurs, the arrange- 

 ment resolving itself posteriorly into a dorsal and a ventral 

 pair of tori, tlie former rounded and short, the latter more 

 elongated. The tori of this (second) region ax'e furnished 

 with minute elongated hooks, having a slender shaft 

 narrowed at its commencement and again toward the neck, 

 the tip ending in a sharp main fang, whilst, iu lateral view, 

 the crown has two spikes above it. 



