60 
THE VOYAGE OF H.M.S. CHALLENGER. 
greater length of the foot generally, as well as that of the ventral bristles. In the dorsal 
bristles of Iphione muricata there is a well-marked difference between the lower and the 
distal spinous rows, the former being wide, the latter most regular and close, the whole 
tip having a broader aspect than in the other species. The entire spinous arrangement is 
also more lax (PL VIIIa. fig. 7 ). In ordinary views the bases of the spines are opposite, 
as in the former species. 
The ventral division of the foot is furnished with paler bristles than in Iphione 
muricata. The upper have elongated tips and well-marked spinous rows, the extremities 
being longer than in Iphione muricata. The next series (PI. VIIIa. fig. 8) are also pro- 
portionally longer, and their spinous rows less prominent. The smooth portion with the 
hook at the tip is evidently longer than in Iphione muricata, and the curve in front is 
different. The upper part of the shaft (below the tip) is slightly marked by indications 
of spinous rows. On the whole the rows of spines are much more distinctly marked in 
Iphione muricata. 
The dorsal cirri have an enlargement below their basal segment. The latter is large 
and cylindrical, and appears almost to represent the body of the organ. The absence of 
the papillae on its surface, however, makes its homology clear. The cirrus proper is only 
about twice the length of the basal division, and is in the form of a slender tapering 
process covered with rather large clavate cilia. The organ seems to be capable of a 
certain degree of invagination within the basal part. The cirri of Iphione muricata are 
much longer, and correspond more with the ordinary structure, showing a short basal 
division, a long tapering ciliated shaft, dilating at the tip, and having a filiform process 
(which is longer than the cirrus proper in the present species) appended to the latter. 
Moreover, the cilia on the surface are much longer and less clavate than in the form from 
the Challenger, The cirri scarcely reach the extremities of the dorsal bristles. 
The ventral papilla is just indicated in this species as in Iphione muricata, and in 
this respect diverges from Lepidonotus. 
In transverse section the body-wall differs from Lepidonotus squaniatus in the longer 
interval between the insertion of the oblique muscles in front and the smallness of the 
flattened nerve-area. The muscular wall of the region, moreover, is comparatively 
thin, and in marked contrast to the species just mentioned. The hypodermic layer of 
the proboscis is perhaps more lax and areolar than usual. 
Kinberg very justly sejDarates the genus Iphione from the other Polynoidse by a 
wide interval, and when to his other characters the opposite condition of the pinnae or 
spikes of the dorsal bristles is added, the distinction is even more decided. The remark- 
able condition of the head and the absence of eyes in the present form are noteworthy. 
De Quatrefages’ species, Iphione glabra, Iphione cimex, and Iphione jimbriata, seem to 
be in need of re-examination, especially as he found no cilia on the scales of Kinberg’s 
Iphione ovata. His descrqDtions are not sufficiently precise to give certainty, and much 
