242 
THE VOYAGE OF H.M.S. CHALLENGER. 
parts have the ordinary structure, the crenations and grooves of the posterior lip involving 
both the buccal segments. 
The maxillse (Fig. 7), like the dental apparatus in general, is blackish-brown, and 
their downward curvature a little beyond the broad region at the base is pronounced. 
The spathulate posterior surfaces are broad, and the ends are evenly rounded. There is 
no constriction. The left great dental plate has five teeth, the right six. The lateral 
plate next the latter is narrow, and ends in a blunt tooth. The outer (anterior) plate is 
much larger, and the inner edge is produced into a sharp tooth. The small plate 
immediately behind is pale brownish, thus contrasting with the rest of the apparatus, and 
it points into the notch next the tooth. The long horny bar passing backward from 
the former bends slightly outward, and terminates in a point quite removed from each 
great dental plate. The four plates just described are symmetrical. The mandibles 
Fig. 7. — Maxill® and dental plates of Lumbriconereis bifurcata, from the dorsal aspect ; x 15 diameters. 
Fig. 8. — Mandibles of Lumbriconereis bifurcata, from the ventral surface ; magnified. 
(Fig. 8) are clavate, the anterior region being broadly triangular, the posterior forming 
slender and tapering shafts. The ventral dentary surface is somewhat semicircular, with 
curved veins from side to side. On each side of the median notch is a tooth. The 
striking point is the downward curvature of the maxillae, both anteriorly and pos- 
teriorly, the elevation occurring just in front of the spathulate posterior region. 
The body is shghtly tapered in front, remains for a considerable distance of nearly 
uniform calibre, and again tapers toward the tail. The feet resemble those of 
Lumhriconereis fragilis in front, but posteriorly they are distinguished by the presence 
of two nearly symmetrical lobes, one in front and the other behind the vertical row of 
