POLYCH^TA-BENHAM. 101 



" cirrus " has increased in size, and has become sub-cylindrical ; the distal upper 

 angle of the foot becomes produced into a distal cirriform process ( ? the " lip " of the 

 chaetophore), in addition to the dorsal " cirrus" (fig. 121). 



The neuropods decrease in size posteriorly, and the inferior angle becomes more 

 marked. 



The general form of the neuropod is similar to that occurring in other Ampharetids, 

 but the presence of both the proximal " papilla " and the distal " supra-uncinal 

 process " seems unusual. The proximal papilla, which I have termed " cirrus," is 

 usually regarded as equivalent to a vestigial notopod; and the distal process to the 

 dorsal cirrus (cf. Fauvel (1897), Ehlers (1887) p. 220). 



The uncinus has five teeth in a single series, and a small prominence between the 

 smallest of these and the rounded upcurved extremity of the plate (figs. 122, 123) ; 

 it is quite similar to that figured for P. crocea by Mclntosh (1885), pi. xxvi a, fig. 25). 



The structure of the gill (f gs. Ill, 112). Although the condition of preservation 

 is not sufficiently good to allow a thorough study of the gill to be made, the 



examination of a short series of transverse sections enables me to give an account of 

 its more striking features. 



The gill axis is traversed by a canal, whose wall is composed chiefly of muscle. 

 Externally there is a layer of tall columnar cells bearing a thick cuticle; within this 

 is a thin circular coat of muscle, which envelopes a thicker coat of longitudinally 

 arranged muscle fibres. This does not seem to be limited very definitely internally, 

 for there is a layer of loose connective tissue, in which are scattered irregularly a number 

 of small round nuclei. At places in the series of sections I believe that I can detect 

 the remains of a thin membrane forming the lining of the axial cavity; but the tissue 

 is here broken and imperfectly preserved, and it may even be that the canal is an 

 artifact, and that the axis is occupied by a core of loose connective tissue. 



Kunning along the wall of the axis at two opposite points is a blood vessel, lying 

 apparently in the longitudinal muscle coat, but in places it projects into the cavity. 



The folia or gill membranes are, of course, cut transversely ; the central part 

 consists of connective tissue, enveloped in the epidermis. I can see no cilia, though 

 perhaps this is due to the state of preservation. A series of blood vessels is exit across, 

 lying close to one another along each side, underneath the epidermis. They give to 

 the section a very characteristic appearance, and seem to be connected across the 

 folium; but I was unable to trace out precisely how or where they communicate with 

 the axial blood vessels. 



Locality. 



Commonwealth Bay, Station 3, 157 fathoms. 



Remarks. That the genus Phyllocomus is rare is evident from the fact that 

 although it was established by Grube as long ago as 1877 for the species 



