336 PROTULA TUBULARIA, 
tuft of the region. This membrane is supported by a greatly developed alar or dorsal 
process of the foot, which tapers distally, and is freely mobile, so that when the annelid 
withdraws itself into the tube this membrane and the bristles are closely applied to the 
dorsum. No spine supports the alar process, so that the muscles of the bristles suffice for 
all its movements, which would appear to be partly respiratory, since its blood-vessels are 
finely reticulated. 
The pore for the thoracic organs is placed on the second setigerous segment in the mid- 
dorsal line (De St. Joseph). The thorax is greenish, the alar membrane veined with green, 
and each segment is distinguished by a band of red. The first segment has two touches of 
orange or red (without crystalline elements), whilst the abdomen is reddish or orange. 
The first region of the body, as a rule, consists of eight segments, viz., the peristomial 
and seven bristled segments. Moreover, as De St. Joseph pointed out, the first and the last 
have glandular scutes on the ventral surface, the first, in a line with the first bristle-tufts, 
being especially large. The first setigerous process and its bristles are usually directed 
differently from those which follow, viz., obliquely upward, forward and outward, the 
rest being in repose placed obliquely upward and backward. The bristles are somewhat 
shorter than those which follow and present more distinct, though very translucent and 
narrow wings. ‘The typical anterior bristles (Plate CX XX, fig. 7) are pale golden and highly 
iridescent, long, slender forms, with straight shafts and but slight curvature of the finely 
tapered tips, the wings being so narrow as to be almost indistinguishable, only a linear streak 
indicating their presence on careful inspection. Such therefore differs from the condition 
in P. tubularia, where De. St Joseph describes and figures the wings as not only distinct but 
striated. The wings are also more distinct in P. intestiénum from the Mediterranean. It 
is possible that friction modifies the wings in this region, and hence the more evident nature 
of these on the first bristle-bundles, which are less exposed. 
The posterior region differs from that in Protula intestinum, for instance, since it presents 
no evident bristles to the naked eye or under a lens, for they are usually so closely adpressed 
as to escape notice, whereas in P. intestinwm the posterior region has on each side a palisade 
of long glistening bristles. Such obscurity, however, is apparently due to friction, since in 
those best preserved similar though smaller bristles occur in this species (Plate CX XX, fig. 
7a). Other tufts show only short shafts dilating gradually toward the distal end, which is 
curved, flattened, and translucent, the slender tips occasionally projecting beyond the 
surface. 
The small variety dredged off St. Peter Port and found between tide-marks at Herm 
has somewhat better developed wings to its bristles, and the tips of the posterior bristles 
are more Clearly scimitar-shaped, being curved backward like Syme’s knife. In others the 
straight tips ended in sharp points, but whether such was due to injury or malformation 
is not at present clear. 
The rows of hooks occur on the ventral side and behind the bases of the bristle-tufts 
in the anterior region, and consist of minute, thin, translucent organs (Plate CX XX, fig. 7a), 
which have a long anterior face ending inferiorly in a shghtly curved spine corresponding 
to the main fang in other forms. The edges appear to be minutely serrated. The 
outline below the main fang forms a narrow gulf, and then trends to the thin basal 
plate. The posterior outline dips inward so as to make a prominent and bluntly conical 
