38 Piof. M'lntosh's Notes from the 



and are quite free from the branchiae. Six or more occur on 

 each side as delicate filaments little tapered toward tlie tip. 

 In the centre are two or three fokled lobes, apparently' in 

 connection with the oral aperture, and near the dorsal fissure 

 is an oblique fold of some length, the distal end of which is 

 split into filaments. What appeared to be the two tentacles 

 proper are on the inner border of each ventral fold, and 

 they terminate in a tapering filament. The mechanism of 

 the entire elaborate apparatus is complex. The length and 

 degree to which the tip is webbed vary considerably, and 

 in the arctic form it is more elongate. 



The cutis is smooth, has a finely iridescent or nacreous 

 lustre, and, when removed, has a bluish aspect. In intimate 

 structure it is crossed by fine lines, which give it a fibrous 

 appearance, but at the segment-junctions white bands occur, 

 and these are tesselated. A series of powerful circular 

 fibres occur beneath the skin and its basement-tissue, whilst 

 the longitudinal bands conform to the type of the family. 



The collar runs smoothly into the first segment, which 

 is of considerable antero-posterior diameter and uniformly 

 rounded. It has on each side, a little in front of the 

 segment-junction, a small tuft of bristles and a pale spine. 

 The bristles are simple winged forms with tapering tips, the 

 edges of the wings being serrated. They slant dorsally 

 forward. Some of these long anterior bristles present 

 a peculiar twist below the wings, but whether this is arti- 

 ficial or otherwise is unknown. The succeeding seven 

 pairs, which issue just in front of the median ring, have 

 modified tufts, consisting of a dorsal series of bristles with 

 tapering tips, like those of the first series, with serrated 

 edges and a ventral series of bristles of spatulate form, 

 the slope of both being obliquely upward and forward. 

 The spatulate bristle is smallest at the base, and gradually 

 enlarges into a finely-serrated shaft, which remains cylin- 

 drical until the wings appear, and then tapers to a blunt 

 point. The wings rapidly widen on each side, and soon end 

 in a blunt tip, are obliquely striated, and have serrated 

 edges laterally. Moreover, the tip often presents a slight 

 marginal fold. When the tip of the shaft is broken, the 

 transparent web connecting the wings is evident and the 

 margins of the wings are stifi*ened by incurvation and slight 

 thickening. There is little difference between the first tuft 

 and the last, except that the posterior are rather more 

 obtuse at the tip. In transverse section the exterior of the 

 bristle is hyaline, the centre granular from the fibres. On 

 examining the bristle-tufts of this region Avitli a lens, a 



