REPORT ON THE ANNELIDA. 
329 
The fourth foot is characterised by the conversion of the ventral cirrus into a scute 
or flattened disk, and the latter occurs on the other segments, apparently to the posterior 
end, though the scutes are less glandular and opaque posteriorly. At the tenth foot the 
dorsal cirrus is short and almost lanceolate from the great expansion at the base, a 
feature very diagnostic when contrasted with Nothria ivillemoesii. There is only a trace 
of the posterior lamella of the setigerous region. The upper bristles of the latter lobe 
are long and finely tapered at the tip. 
The branchise commence on the seventeenth foot, either as a simple process, or as 
one with a bifid tip. At the twentieth foot the branchia is still bifid, and from the first 
is much longer than the dorsal cirrus which is attached to its base, so that the cirrus 
resembles a process of the main branchial stem, especially as a large blood-vessel enters 
its substance. The dorsal bristles proceed only a short distance into the cirrus. The 
main branchial pillar at the thirtieth foot splits into three long terminal divisions and a 
shorter process, and thus diverges quite from the lateral branching of the organ in 
Nothria willemoesii. The upper bristles of the setigerous process are very long and 
much tapered, with a slight curve at the tip. At the fortieth foot there are still three 
branchial divisions and a small fourth, but all are shorter. At the fiftieth foot the 
branchial process is simple, and, moreover, it is shorter than the dorsal cirrus. The 
comparatively greater length of the bristles than those in Nothria willemoesii is evident. 
The branchia is much less at the sixtieth foot, and disappears altogether before the seven- 
tieth is reached. From the tenth foot backward the dorsal cirrus diminishes in bulk but 
increases in length. In regard to the structure of the bristles in the upper series of the 
setigerous lobe, it is apparent that they are larger and more finely tapered than in the 
previous species, and much more so than in Nothria conchylega. The tips have a narrow 
wing on each side. A curved tapering appendix occurs on the extremities of one or two 
of the spines in the twentieth foot. 
The long posterior hooks (PL XXVIa. fig. 6) have a smaller and more erect distal 
process than in Nothria willemoesii, and the large prong is more acute. These hooks 
become much more slender toward the posterior end of the animal, but they retain for 
the most part their proportions, except that the distance between the bifid tip and the 
striated region is greater, showing that considerable elongation has occurred. 
The brush-shaped bristles (PI. XXVIa. fig. 7) have rather narrow elongated tips and 
fimbriae. They differ, therefore, from those of the previous species, just as the long- 
simple bristles do. 
The tubes are of great length, viz., upwards of 500 mm., with a diameter ">f 5 or 6 
mm. They are for the most part rounded and firm, composed externally of dark greyish 
mud, only slightly coherent, and internally of a tough whitish secretion with a glistening 
surface. One end is somewhat bulbous and almost closed. So far as the specimens show 
there is no special structure at the open end. On the whole such tubes are much more 
(ZOOL. CHALL. EXP. PART XXXIV. • — 1885.) LI 42 
