REPOET ON THE ANNELIDA. 
499 
the ventral surface, is marked by a hiatus. On each side of the median line ventrally 
it terminates in a long triangular flap, which is mottled with purplish-brown internally. 
In every instance the tube and its secretion are fixed to the latter, and cannot be 
removed without rupture. 
The branchise, which as a rule are the only parts that escape adhesion to the tube, are 
about twenty-six on each side, two or three at the ventral edge of the fan being short 
and small. The radioles, which are by no means stiff, seem to have their external 
surface grooved. Toward the base the fan presents both dorsally and ventrally a series 
of tolerably uniform purplish-brown bands, from the regularity with which the pigment- 
specks on the radioles are arranged. Distally the pigment is less uniform, though rows 
are occasionally seen. Each radiole, for instance the first dorsal, shows about twenty- 
three pigment-specks, from base to aj)ex, the brownish pigment deeply tinting the pinnse 
at each spot, so that during expansion the appearance in life must have been beautiful. 
The axis of the radiole, marked by transverse bars, becomes cellular towards the tip. 
Externally the radioles are furnished at somewhat regular intervals with pairs of 
appendages, as in the previous species, only the elevations and the superior or terminal 
processes are more distinctly developed (PI. XXXIXa. fig. 4). The pinnae, which 
become shorter toward the extremity, rather abruptly diminish to four or five short 
papillae, and cease, the terminal filament being in the preparations slightly enlarged 
in the middle and constricted below the somewhat bulbous tip. 
The number of segments in the anterior region appears to be eight, but, as formerly 
mentioned, a clear view of these is not attainable. The long dorsal bristles (PI. XXXa. 
fig. 19) have slender tips with narrow wings ; while the inferior shorter series possess 
wider wings and a less attenuate termination (PL XXXa. fig. 20). Besides these, as 
usual, a series that hardly projects beyond the setigerous lobe occurs. The tips of 
these are shorter and the wings considerably broader. The extremities of the posterior 
bristles are extremely elongate. 
The anterior hooks (PI. XXXa. fig. 21) show a moderately developed crown, with 
about six or seven small teeth in profile above the great fang. The neck is rather 
elongated, and the basal prolongation posteriorly comparatively short. The anterior 
projection or prow is gently curved, the distance between the base of the great fang and 
the basal line being great. The posterior hooks present more distinctly developed teeth 
above the great fang. 
The structures recognisable amongst the greyish mud forming the faecal pellets are 
numerous Diatoms, and a few Eadiolarians and minute ova. 
The tube is constructed of greyish mud, and microscopically contrasts strongly 
with the foregoing, in regard to the large amount of quartzose sand-grains, fragments of 
sponge-spicules, and minute arenaceous Foraminifera. It is friable, and easily detached 
from the branchial region, but the secretion glues it to the rest of the animal. Toward the 
