202 
THE VOYAGE OE H.M.S. CHALLEHGEK. 
than in the previous form, and no long bristles are present. The commencement of tbe 
alimentary canal is clearly seen, but is soon lost in the opaque mass of ova. 
In the specimens from the Challenger, only a fragment of the posterior end of a 
male example was procured, but in the fine example of the sj)onge kindly forwarded from 
the Oxford Museum by Prof. Moseley a perfect male occurred. This dorsally presents 
a head (PI. XXXI Va. fig. 12) with a median notch to which apparently a process 
from the body of the parent-stock had been attached. The sides form two sym- 
metrical but irregularly rounded lobes, a small eye being situated anteriorly and 
towards the outer border on each side. The , eye is circular and smooth in outline, as 
if surrounded by a special capsule. On the ventral surface a much larger pair of eyes 
are situated somewhat behind and internal to the dorsal. The head seems to have 
a single tentacular process. Immediately behind the head on each side are a 
pair of connate processes, probably developing feet. Seven segments which follow 
the foregoing are somewhat narrower (transversely) than their successors, the feet 
especially being less developed. Each has a short dorsal cirrus, a tuft of bristles 
with stout shafts and short terminal pieces, which appear to have simple tips. 
One or two of the posterior segments of this division also have a short tuft of s im ple, 
bristles, but these do not project conspicuously from the foot. The succeeding region of 
the body, which in the specimen consists of about twenty-six segments, gradually 
diminishes to the posterior extremity, at which is the anus, with a minute (developing 
foot) at each side (PL XXXIVa. fig. 13). The alimentary canal leads from the anterior 
central notch straight through the body to the posterior end. 
The feet (PL XXXIII. fig. 13), which are well marked and long, have dorsally 
a slightly convex margin ; ventrally the outline is also somewhat tumid at the base, 
but curves upward toward the tip. A short cirrus of four or five segments extends 
from the extremity of the dorsal margin, while beneath it is a dense tuft of long, 
straight, sword-shaped translucent bristles, similar to those described in the female bud. 
A flat papilla, about the middle of the bristle-bundle, shows that part of the foot 
to which the tip of the slender supporting spine proceeds. This slender spine diverges 
upward from the side of the stronger inferior one, the arrangement of the parts 
indicating that the foregoing tuft of simple bristles is of less morphological value than 
the others. A somewhat lanceolate j)rocess occurs at the ventral margin of the foot, and 
apparently corresponds to the setigerous division. It is supported by the stronger 
spine, and bears two or three bristles with simple terminal processes, similar to those 
in the parent-stock. The enlarged feet evidently greatly aid in storing the spermatozoa, 
and they have a series of muscular fibres, which form a closely arranged investment, 
crossing if not interweaving with each other. The cavity of each foot is occupied by a 
granular mass, which in some clearly shows the forms of spermatozoa. 
The condition of the specimens renders the structure of the body-wall indistinct. 
