EEPOKT ON THE ANNELIDA. 
321 
The body is slightly narrowed in front, then maintains a nearly uniform diameter 
throughout the greater part of its length. Towards the tail it again tapers. 
The head (PL XLI. fig. 2) is furnished with moderately elongated tentacles, the median 
being shorter than the adjacent. From the shape of the head the bases of the external 
tentacles are carried further forward than in the common form [Nothria conchylega). 
The frontal tentacular lobes are similar. The tentacular cirri are about the same length. 
The dental apparatus (Fig. 77) is pale madder-brown, with darker touches in the usual 
positions, and a blackish-brown band between the maxillae and the posterior processes. 
The maxillae are distinctly widened in the middle. The posterior appendages have the 
same inclination as in the last species, are slightly contracted behind the maxillae, and 
then form broad plates without a median notch posteriorly. The left great dental plate 
has six teeth behind the long anterior fang, the right nine teeth. The left lateral paired 
plate possesses ten, and the unpaired eleven teeth. The right lateral shows ten. A 
single, somewhat rectangular, accessory plate exists on each side. Its anterior and inner 
edge rises into a small blackish tooth. The rest of the surface is pale brownish. The 
mandibles (Fig. 78) have about three prominent denticulations along the cutting edge, 
and the posterior dental region is separated by a transverse or slightly oblique line as in 
the former species. 
The post-buccal region consists of two segments, the posterior having the larger and 
more lobate ventral cirrus. 
The first pair of feet are directed as far forward as in Nothria conchylega, but differ 
in having no median cirrus, while possessing both dorsal and ventral cirri and a 
setigerous flap. The bristles (PL XXIIa. fig. 6) have a somewhat abruptly curved tip, 
with a hooked terminal fang, and a broad, pointed process immediately beneath. The wing 
extends considerably above the former, and also runs into the shaft very gradually. 
The branchiae are represented in some on the eighth foot by a small process. The 
ninth has a well developed, long, simple branchia ; and they continue of the same shape 
nearly to the posterior end of the body, the exact arrangement at the tip of the tail 
being unknown, since the specimens are imperfect. The branchial processes are, indeed, 
conspicuous features, the long, tapering filaments being about a fourth less than the 
diameter of the body, and often gracefully coiled at the tip. At the tenth foot the 
branchia is considerably longer than the dorsal cirrus ; at the twentieth it is more than 
twice as long as the latter, and throughout (PL XLI. fig. 3) it is much larger and thicker, 
though this condition depends to some extent on the state of the blood-vessels. 
Dorsally is a group of the ordinary long bristles with straight shafts, and curved and 
finely tapered tips ; then two long, stout hooks (PL XXIIa. fig. 7), which have a slight 
curvature backward at the tip, and two strong fangs of nearly equal size, as in the 
Onuphis verngreni of Kinberg.^ In all these hooks the wings form a symmetrical pair 
^ Ofversigt k. Vetensk.-Alcad. ForJiandl., 1864, p. 560, Taf. xiv^ fig. 8 (Freg. Eugen. Eesa). 
(ZOOL. CHALL. EXP. — PART XXXIV. 1885.) 
LI 41 
