308 
THE VOYAGE OF H.M.S. CHALLENGER. 
wrinkled and uneven. The median triangular areas are similar to the foregoing. The 
left great dental plate shows seven, the right seven or eight teeth. The left lateral 
paired plate has six teeth, and outside is an accessory plate with a conical tooth. The 
left unpaired lateral has eight teeth. The right lateral has eight or nine teeth, and the 
accessory plate also has a pointed tooth. Beneath the paired 23late on each side is a 
blackish -brown alveolus. The mandibles (Fig. 64) are slightly fixed at the base of the 
dental surface, which is jDetaloid, with the broad end of the lobe directed forward and 
irregularly denticulated on the edge. On the dorsal surface (Fig. 65) a short dark line 
occurs on each side of the fissure towards the jDosterior region of the dental surface. 
This S 2 >ecies differs from Notliria concliylega in the structure of the first foot, and 
it is much less 2 >roduced anteriorly. The foot has a dorsal cirrus, a broader though 
shorter process from the jDO'sterior border of the setigerous lobe, and a ventral cutus, 
the tip of which does not extend so far outward as the latter. This type continues 
in five or six feet, and a few then show only the dorsal and ventral cirri. About the 
ninth or tenth (occasionally the eleventh) foot each branchia commences in connection 
with the base of each dorsal cirrus as a simple filiform 2 >rocess, which increases in length 
to the twentieth, by and by becomes bifid (PL XL. fig. 9), and again forms a simple 
j)rocess before reaching the fortieth foot. It ajDjDears to continue in the latter condition 
till near the tip of the tail, though no specimen is comjfiete. The ventral cirrus dis- 
ap 2 >ears about the tenth foot. 
The bristles of the first foot (PI. XXIa. fig. 24) are 2 >eculiar in showing a large ter- 
minal and two smaller inferior fangs, besides an articulation of the terminal region as in 
Sthenelais. The latter is also seen in an elementary condition in Notliria somhreriana. 
The sujDerior bristles are characterised by their great length, translucency, and finely 
tapered condition. The wing or guard is just distinguishable at the margin. At the 
twentieth foot they form a dense tuft, which projects considerably. The inferior bristles 
of this kind, again, have short though acutely pointed tips and short shafts. 
Two prominent hooks occur inferiorly before reaching the thirtieth foot. These 
(PI. XXIa. fig. 25) have a powerful inferior fang, and a well marked superior one which 
indicates, by its forward curve, the condition in allied forms, in which both are nearly 
equal in length. Moreover, posteriorly the proximal fang increases in size (PI. XXIa. 
fig. 26). 
No trace of a tube occurs in the preparation, with the exception of a minute, 
translucent soft chitinous one, which may be unconnected with the specimen. 
Some of the fragments pertain to females, and are full of ova. 
The minute intestinal masses consisted chiefly of greyish sandy mud, with a few 
Diatoms, minute bristles of Annelids and fragmentary spicula, apparently of Sponges. 
In transverse section the nerve-area differs from that in Notliria conchylega, Sars, 
for the cords lie close to the circular coat, and are completely wedged in by two lateral 
