POLYCH^ETA BBNHAM. 99 



These structures appear to be the " areolee " of Grube's account of Phyttocomus 

 crocea (1877, p. 543), and the relative disposition of them seems to correspond to 

 the three structures figured by Mclntosh (1885), pi. XLV11, fig. 11), which he 



interprets as the bases of lost " gills." 



These three pairs of channels and tunnels appear to be unique, and I regret that, 

 having only a single specimen of the worm, I am unable to examine them by sections. 

 I have no suggestion to make as to their purpose. The worm is well preserved, and 

 there is no evidence of rupture here, no suggestion that any structure, such as a gill, 

 has been broken away ; the margins of the channels are rounded and smooth, and appear 

 quite natural. At any rate, under the highest power of a dissecting microscope I can 

 see no sign of any interruption in the continuity of the surface. 



The tentacles, as is usually the case in the family, are invaginated into the 

 buccal cavity. They were exposed by slitting up the side of the body along a line 

 corresponding to the junction of the lower lip with the peristomium (fig. 113). TLen 

 numerous filamentous tentacles are seen directed backwards along the roof of a cavity, 

 which I suppose is the buccal cavity; they are borne by a rounded ridge, which extends 

 across the base of the prostomium, curving forwards on each side till nearly in the line 

 of the lateral margin of the lower lip (fig. 116). 



Within the lower lip, along its base, is a second rounded ridge which connects 

 right and left with the tentacular ridge; it is apparently a sphincter muscle, and may 

 be exaggerated by the contracted (-/bate of the worm. 



The tentacles are 10 mm. in length and are united to one another for a distance 

 of about 3 mm. from their origin, where they are only indicated by lines separated by 

 shallow furrows. The proximal portion of the tentacles is surrounded by a thin 

 membranous flap, 1 mm. in height, springing from the tentacular ridge; and when 

 the tentacles are lifted up a line of brown-red pigment-dots is seen close to its free 

 margin on its tentacular surface; further, a second line of darker spots lies along its 

 base, close to the roots of the tentacles (fig. 117). 



The body. The dorsal surface is smooth, annulate and without inter-segmental 

 furrows, but the segments are distinct enough laterally and ventrally ; the body is 

 very strongly arched, so that the notopods are directed upwards ; the third segment, 

 like the r.ext two, is much narrower than the following, though whether this is again 

 due to the strong contraction of the worm seems doubtful, in light of the statement by 

 Grube that in his species these three segments are shorter than the rest. 



The third segment carries the first notopod, which is smaller than the following, 

 and bears only a few chaetse. The next two notopods are likewise small, but the number 

 of chsetae increases ; the maximum is attained at about the sixth or seventh, and this 

 is retained until the fourteenth. 



The bristles are long, stout and of a golden-yellow colour ; they are arranged in 

 a single vertical series with longer ones above and successively smaller ones below. 



