222 
Darwin did not know the soft parts of this species. Therefore I used thore of the 
Siboga-specimen to make up this deficiency. 
Mouth. Labrum (Pl. XXII, fig. 21): notch very wide at entrance, triangular, not 
very deep. Lateral parts bear three teeth on each side of notch and have rounded corners. 
The height of the sub-triangular shield is considerable and almost equals its greatest width. 
Palpi ovate, with the free extremity rounded, the upper margin slightly, the inferior 
margin strongly bowed. The outer surface bears a double row of longer hairs or bristles, 
beginning at the free extremity and making an angle with the inferior margin; the same 
surface shows a group of such longer hairs disposed near the free extremity of the palpus. 
The margin of the palpus at the extremity, and the inner surface near that extremity are 
bordered by a number of quite microscopic hairs or ciliae, The latter surface bears a row 
of curved hairs at some distance from the upper extremity, which hang over the edge of 
the labrum when the palpus is not uplifted. The hairs arranged along the upper margin are 
short and not numerous, and go over towards the basis of the palpus in a group of hairs of 
equal size, scattered over the inner surface. 
Mandible (Pl. XXII, fig. 22): the free edge has five distinct teeth and an inferior 
angle. Teeth 1 and 2 strong and pointed, tooth 2 with additional tooth, 3 blunt, with small 
additional tooth, 4 small, distinctly double-pointed; 5 also small, pointed; inferior angle termin- 
ating in three delicate flat teeth. 
Maxilla (Pl. XXII, fig. 23): the free edge is relatively long and bears 2, 4 and 2 
spines, the upper pair consisting of a broader and a somewhat narrower spine which are situated 
close together. There is a small but distinct notch (Pl. XXII, fig. 23*) at the base of which a few 
delicate hairs are discovered; then four somewhat thinner and shorter spines, and two long and 
slightly flexuous spines, situated at some distance from the inferior angle, the remaining part of 
the edge bearing about 5 delicate and relatively short spines. Such a shorter spine is also seen 
at the base of the second spine of the upper pair. Upper and lower margins not parallel 
but together forming an angle, shape of maxilla triangular in consequence. 
Outer maxillae (Pl. XXII, fig. 24): the outer lobe is oval, short and remarkably 
broad. The tuft of spines seen along the upper margin and over inner surface of superior half, 
rather dense; few hairs only scattered over inferior half of same surface. Inner lobe broad and 
rounded, covered with numerous hairs, the longer ones seen along inner margin, rather strong 
and feathered and bent downwards and inwards. 
Cirri. First pair has the branches unequal in breadth and, probably, in length also. 
The longer branch, however, is broken off in both cirri. The shorter one has 8 to 9 segments, 
which are distinctly protuberant on their inner face. These protuberances are covered with 
a dense group of straight and relatively strong spines. 
Second pair has the branches slightly unequal, of 8 and 9 segments respectively; the 
5 to 6 inferior segments are protuberant on their inner face. The protuberances bear numerous 
short and relatively strong spines arranged in several rows. 
Third pair different from second by the inner faces of the segments being less 
protuberant and by the protuberances bearing only a single transverse row of spines. The 
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