138 
THE VOYAGE OF H.M.S. CHALLENGER. 
extend downward below the superior series of the next kind, which are stout browTaish 
spines characteristically curved at the ends, which latter are also shghtly dilated. Some 
of these, from the inferior edge of the series, show toward the tija a minute filiform process 
after the manner of Kinberg’s Eupompe grubei (PI. XIIIa. fig. 3). The stronger bristles 
again, are more deejaly tinged with brownish, and have an extremity which is blunt, appa- 
rently from wear (PI. XIIIa. fig. 4), and the curved transverse lines at the base of the tip 
are more distinctly marked. These bristles are very brittle, and the majority are removed 
in handling the specimen. The curve at the tip probably indicates a connection with the 
type of the smaller kind (fig. 3) with the filiform process, which in most cases has been 
abraded. They diminish in size from above downward. The bristles which form the 
ventral tuft are of two kinds, the larger (PI. XIIIa. fig. 5) presenting a more conspicuous 
terminal dilatation, while the smaller (PI. XIIIa. fig. 6) and more numerous have long 
slender translucent shafts, with prominent spinous rows on the enlargement superioiiv, 
the extremity being in the form of a long tapering process closely and regularly beset 
with fine spikes, so that it resembles a slender feather with its barbs. These bristles also 
decrease in size from above downward. The dorsal cirrus arises from the upper and pos- 
terior edge of the foot, and is often inconspicuous amongst the large papillae, from 
which, however, it is distinguished by its basal joint, conical terminal region, and greater 
length. It forms a comparatively short, tapering process with a broad basal segment. 
The ventral cirrus is now comparatively short, and its tip does not reach the extremity 
of the setigerous region. 
In the structure of the body-wall this form for the most part agrees with 
Panthalis cerstedi, Kinberg. The much greater size, however, emphasises various 
features. Thus the nerve-area is separated by a definite and firm basement-layer vTich 
comes from under the great longitudinal ventral muscles on each side, bends upward 
round their inner edges, and forms a transverse platform above the region. From 
the upper and outer angle on each side a process of this basement-tissue runs upward 
amongst the fibres of the oblique muscle, indeed, many appear to be inserted into it. 
Moreover, the whole upper surface of this basement-layer is occupied by the insertion 
of two great vertical muscles, which in this region (the anterior third) pass down from 
the proboscis. Such fibres do not occur in front, and are probably local. The nerve- 
area varies in appearance according as it is severed in the line of the ganglion or 
between them. In the former case it presents a large elliptical space with a protective 
layer of hypoderm externally (thick in the median line and tapered at each side), with 
traces of at least two small neural canals toward the middle line of the ganglia 
interiorly. A series of convexities on the ventral surface seem to indicate the ganglionic 
regions. The interganglionic portion, on the other hand, is in each case slightly concave 
(upward) and the cords are flattened, so that the area is much diminished. The ventral 
longitudinal muscles are very large, and show a fissure running obliquely outward and 
