REPORT ON THE ANNELIDA. 
249 
area fits into the hollow of the latter near the tooth ; and behind a slender bar runs 
backward to the side of the maxilla. The ventral surface of the mandibles (Fig. 15) 
has a dentary surface resembling a pair of bivalves (in one), or somewhat crescentic. 
The surface is marked by fine concentric lines, and a touch of dark pigment occurs 
at the outer angle. The lines are very distinct on the dorsal surface. 
In variety B the maxillse show a more distinct outward bend or “ knee ” posteriorly, 
the left great dental plate has four, the right five teeth. The two lateral plates are similar, 
but no minute external denticles occur on the anterior or outer. The ventral dentary 
surface of the mandibles is nearly semicircular, with a large amount of pigment at the 
outer angle. The lines are also concentric. 
The general appearance of the feet (PI. XXXVI. fig. 19) resembles that in Lumhri- 
conereis fragilis ; but in structure the bristles approach those of Lwnbriconereis ehlersii. 
At the tenth foot the arrangement is closely allied to that in the latter, the chief 
differences being in the minor details of length and proportion. 
Two varieties, however, occur in regard to the structure of the feet, viz., one (A) with 
black spines and bristles with deeply tinted shafts. In the tenth foot there are three 
black spines, and the bristles seem to be slightly longer than in the next form. Indeed 
in the succeeding feet {e.g., about the thirtieth) the great elongation of the winged bristles 
(PL XVIIIa. fig. 5) is a marked characteristic in comparison with the other form. In 
this respect it resembles a variety (D) from the “Valorous” Expedition, which, however, 
does not show black spines. 
The variety (B) with the shorter bristles has at the tenth foot two winged bristles in 
the superior group; three in the second, five winged hooks (PI. XVIIIa. fig. 9) arranged 
in pairs, the odd one being inferior ; and lastly a single winged bristle at the ventral 
edge. The differences between a winged bristle from the same foot in each is well 
shown by comparing the figure of that in the former variety with PL XVIIIa. fig. 8. 
Whether these differences have any relation to the sex remains to be seen. 
The posterior hooks of the two varieties are closely allied, yet it is evident that the 
hooks of the long-bristled form (PL XVIIIa. fig. 6) are longer than those of the kind 
\wth shorter bristles, and slightly different in outline at the upper part (PL XVIIIa. 
fig. 7). 
The black spines occur chiefly in the anterior region of the long-bristled variety. 
It is difficult, perhaps, to say how much reliance should be placed on the characters 
which show divergence in these two forms, but it is well to indicate them. 
In the intestine of the type with long bristles is a little muddy sand containing the 
hairs of minute Crustacea, a few Diatoms, and sponge-spicules. 
The pedicle of the nerve-area in section is moderately developed, and the neural canal 
superiorly is much less than in the typical form. The whole area and pedicle form a 
pear-shaped mass, resting on the circular coat, which is comparatively thick. 
(ZOOL. CHALL. EXP. PART XXXIV. 1885.) 
LI 32 
