46 
THE VOYAGE OF H.M.S. CHALLENGER. 
bottom temperature 35°’3, surface temperature 70°'5 ; red clay. Most of the specimens 
were loaded with mud or ooze of varying character, according to the nature of the ground, 
and it adhered most tenaciously to the bristles. 
There is little in external appearance to distinguish it from its congeners except 
perhaps the very great length of the dorsal spines, the greater delicacy of the scales, the 
greyish muddy coating of the bristles, and the smoothness of the ventral surface. The 
latter presents only a few minute papillae, which are somewhat conical in shaj^e, and a few 
also occur in the middle of the dorsum, The length of a large example is about 48 mm. 
The number of segments is about thirty-three. 
The head is somewhat smaller than in either of the foreg-oino’ and the attachment of 
the first pair of scales infringes considerably on its area posteriorly, in contrast with those 
alluded to. The ocular peduncles are more globular, and they are eyeless. The median 
tentacle is a similar elongated tapering structure with the peculiar enlargement at the 
tip. The papilla in a line behind the ocular peduncle is much less developed than in 
either of the foregoing, forming a barely appreciable eminence just in front of the attach- 
ment of the first scale. The lateral regions of the head are very prominent. The palpi 
are somewhat longer than in Lcetmonice pi'oducta, var. ivyvillei, but show the same 
microscopic cuticular papillae. Between their bases is a papillose wedge, the papillae 
being much less developed interiorly than in the last-mentioned form. Behind the oral 
region ventrally is the usual longitudinally grooved area, which, however, has only 
small papillae at the sides ; indeed, the whole ventral surface is in contrast with that of 
either of the former species, for it is smooth and glistening, under the naked eye, the 
lens, and the microscope. 
It is unnecessary to go into the arrangement of the scales on the different feet, since 
they follow the same rule as in the previous forms. Their number is generally fifteen 
pairs ; and they are also more delicate and diaphanous, exhibiting under the microscope 
a finely granular condition with radiating lines. 
The dorsal bristles (forming the great spines) are considerably larger than in the 
preceding, and while their shafts are large and flattened, the tips are relatively small 
(PI. Ya. fig. 1), and, as represented in the drawing, present a distinct curve in certain views. 
They are grooved at the base and have a peculiar reddish-brown sheen. The number of 
recurved hooks at the tip varies, but the average is three or four. One showed the 
peculiarity of having a series of small teeth on each side below the larger. The simple 
bristles as a rule have minute spikes directed downward toward the terminal region, a 
condition less marked in the previous forms, though the amount of adventitious structures 
often obscures their minute characters. The granulations are probably modifications of 
this feature. One of the hairs from the dorsal tuft overlapping the scales is represented 
in PI. IVa. fig. 12, The longitudinal striae are very distinctly marked in these bristles. 
