EEPORT ON THE ANNELIDA. 
501 
elongated cells, with a median junction. Moreover, the axis of each pinna comes off 
therefrom as a bulbous cellular process. The radiole tapers toward the tip, the pinnse 
diminish to mere papillse, and finally a bare terminal filament only remains. The pinnse 
are purplish and pale alternately, the reddish-brown bars on the radioles apparently not 
affecting them to any appreciable degree. Each reddish-brown bar on the radioles has 
a pair of lateral (ocular) pigment-spots. 
The anterior region of the body consists of eight segments. The dorsal bristles are 
unusually slender and attenuate, at the tip, and the wings are very narrow, though 
distinctly serrated (PL XX Xa. fig. 22). The inferior group present a less elongated 
extremity and a broader wing (PI. XXXa. fig. 23), and they also appear in many cases 
to have a more decided curve toward the tip. The posterior bristles preserve the 
same relative proportions, the dorsal being extremely elongate, while the serrations on 
the margin of the wings of the inferior bristles are very distinct. 
The hooks in the anterior uncinigerous rows are characteristic (PI. XXXa. fig. 24), 
presenting a boldly curved neck, the outline from the crown to the base of the posterior 
process forming one continuous convexity. A single tooth only exists above the great 
fang. The anterior projection or prow is largely developed. The posterior basal process, 
again, is short, and inclines downward at the tip. 
The fine greyish mud in the alimentary canal presented numerous Diatoms, a few 
sponge-spicules and Radiolarians. The transparent cylinders with the attenuate points 
were also common. 
This and the foregoing forms differ considerably in the structure of the body- wall from 
Dasychone dalyelli. In the present instance the hypoderm in section is fairly developed, 
and the basement-tissue beneath is in many parts supplied with blood-vessels. These do 
not appear to pass into the hypoderm proper. The circular coat is very strong dorsally, 
spreads out about the inner third of the longitudinal ventral muscles, and extends over the 
whole of the central area beneath the hypoderm. In this region numerous blood-vessels 
are present. The longitudinal dorsal muscles are more massive and less extended than 
usual, and a marked hiatus exists in the median line. On the other hand the ventral are 
considerably flattened. Posteriorly a median furrow appears in the hypodermic process 
on the ventral surface ; and the longitudinal dorsal muscles are much extended. The 
perivisceral chamber contains many small ova. 
Dasychone ivyvillei, n. sp. (PI. XXXIa. figs. 1-3). 
Habitat . — Found between tide-marks at St. Thomas, West Indies, March 23, 1873. 
The body of this large and massive species measures 74 mm. without the branchiae 
(which are absent). The transverse diameter of the body just behind the thoracic 
region is 10 mm. 
