170 
THE VOYAGE OF H.M.S. CHALLENGER. 
of the eye are two minute processes, and the snout beneath has a larger cirrus on each 
side ; the latter, however, are imperfect. The segment following the head has dorsally 
a transverse row of four basal processes (apparently cirri), two larger lateral, and two 
smaller median. Another is placed on each side a little behind the eye and in front of 
the outer or lateral just mentioned ; and one or two of the anterior feet seem to have had 
similar dorsal processes. In no case was any appendage present. 
As formerly mentioned, all the superior lamellse are absent, wdth a single (loose) 
exception at the anterior part of the dorsum. This dorsal lamella is somewhat heart- 
shaped, of a dusky brown colour, and has the ordinary structure in the Phyllodocidse. 
It arises from a prominent dorsal pedicle, and similar processes occur on the other feet. 
The latter are conspicuous, the bristles projecting somewhat stifSy outward, so as to form 
a nearly uniform lateral series. The setigerous region is well-marked, and is very slightly 
if at all bifid or dimpled at the tip. It is supported by a stout black spine (the same 
structure in Genetyllis lutea being pale), and gives origin to a fan -shaped fascicle of 
translucent bristles (PI. XVa. figs. 2, 3, the former representing the tip on edge), the 
shafts of which have slightly dilated ends, and a shorter terminal appendage than 
in Genetyllis lutea. The serrations on the latter are so fine as to escape ordinaiy 
observation. 
In transverse section the body-wall seems to dilfer both from Eulalia viridis and 
Phyllodoce groenlandica in type, and it does not approach Alcio])e more closely. Both 
dorsal and ventral longitudinal muscles are more powerful, and the fasciculi appear to be 
coarser. The nerve-cords and ganglia are larger than in any of the preceding. 
The ventral longitudinal muscles seem to be less extended transversely, having an 
ovoid form in transverse section. 
The structure of the cephalic region and eyes of this form have been, at my 
request, most carefully examined by Dr. Marcus Gunn, M.A., one of the ophthalmic 
surgeons of Moorfields Hospital, London, of whose special acquaintance with the 
minute structure of both vertebrate and invertebrate eyes I have often had occasion 
to avail myself. 
On the Eyes and Cephalic Ganglion.^ — The eyes of Genetyllis lutea, although 
scarcely to be compared with those of the Alciopidse, are still well marked objects. 
They are recognised as two hemispherical projections, situated one on each side of 
the anterior part of the head, and placed close together. The optic axis of each is 
directed outwards, forwards, and a little downwards. 
Each eye rests, by a very broad base, directly on the cephalic ganglion, while its stout 
outer coverings are evidently prolongations of the cuticle of the neighbouring part of the 
head. On making an antero-posterior horizontal section through the eyeball, it is found 
1 Contributed by Dr. Marcus Gunn. See Narr. Cliall. Exp., vol. i. p. 629, 1885. 
