284 
THE VOYAGE OF H.M.S. CHALLENGER. 
Most of the tips of the jointed bristles have been rubbed off, so that it was vdth 
some difficulty that a complete example (PL XXa. fig. 8) from the middle of the body 
was obtained. The serrations along the edge of the distal end of the shaft are 
very minute, probably from abrasion, the surface having only a slightly punctated 
appearance. The ends of the spines in the setigerous division of the foot are often 
slightly worn. The tip of the hooks from the posterior region (PI. XXa. fig. 9) 
presents a somewhat elongated terminal process with a strong main fang beneath. 
The curves of the extremity and general contour of the hook seem to differ from those 
of its allies. 
The foot in the specimen from Samboangan (PI. XXXVIII. fig. 17) bears two 
blackish spines, but no inferior hook is present. The dorsal cutus is thicker and less 
tapered than in that from Port Jackson. Moreover, the jointed bristles appear to diverge 
considerably from those of the Australian form. Thus (PI. XXa. fig. 10) the direction 
of the lower jDrocess at the tip is upward, and the entire hook is shorter and stouter. 
The shape of the distal end of the shaft also differs, and while the convex edge (as in 
its allies) is distinctly serrated, the whole surface of this region is further minutely 
granular like shagreen. 
The intestine in that from Samboangan contained masses of sandy mud loaded with 
sponge-spicules. Diatoms, a few fragments of Crustaceans and Algae, and here and there 
bright red spicules, apparently Holothurian. In the Australian example masses of Algae 
filled the alimentary sacculations. 
The great size of this form shows the disproportion between the dorsal and the 
ventral muscles, the area covered by each of the former being nearly double that of the 
latter. The dorsal muscles have three folds above the great inferior lobe. The vertical 
muscular bands passing down from the median line penetrate the circular muscular coat 
and are lost in the hypoderm. The oblique muscles proceed by the side of the nerve- 
area and decussate beneath it, the fibres running on each side into the circular coat. 
The nerve-area is somewhat wedge-shaped, wide above and narrow below. Externally 
the investment is soft and granular, so that the denser central region is clearly outlined. 
The latter is constricted in the middle, and has two opaque spots toward its upper 
border. The median neural canal is of considerable size. A little above the nerve-area 
and beneath the blood-vessels is a median canal. 
The section of the same region (anterior third) of that from Samboangan differs in 
the very great vascularity of all the tissues beneath the hypoderm. The size of some 
of the vessels in the circular muscular coat is strikino;. The neural canal is much more 
dilated, and it is surrounded by an opac[ue belt inferiorly. The decussation of the 
fibres from the oblique muscles below the canal is less evident. An opaque band occurs 
in the circular coat in the median line inferiorly. 
