18 Prof. M‘Intosh’s Notes from the 
form than Spio gattyi, and the aspect differs. The head is 
characteristically trilobed, a rounded median lobe projecting 
in front and supported by two lateral lobes a little further 
back. ‘Two eyes occur toward the posterior border of the 
head. In lateral view the snout is bluntly conical, the 
central or prostomial region being nail-like and the mouth 
opening a little behind the tip. A short median tentacle 
occurs on the prostomium and a brief ridge appears to be 
continued a short distance backward to end in a small process 
or tentacle. The body is slightly narrowed anteriorly, 
is more distinctly diminished posteriorly, and ends in 
four foliaceous lobes or cirri. It is flattened both dorsally 
and ventrally, the upper surface carrying the branchiz and. 
the ventral surface being marked anteriorly by lines of dark 
pigment on the terminal region behind the mouth, and with a 
dark line in the middle of each segment-junction for ten or 
twelve segments following. 
The first segment bears a broad sabre-shaped branchia, 
which overlaps its fellow of the opposite side behind the 
snout. It has a single lobe, the longer margin being 
inferior, and a tuft of finely tapered bristles which show 
a narrow margin distally on each side. Above these is a 
shorter tuft, slightly differmg in direction. The second 
foot has a similar ventral lobe, a tuft of curved bristles, 
and, in addition, a superior lobe confluent with the branchia 
and carrying a tuft of longer bristies, finely tapered, but less 
curved distally. At the tenth foot the ventral lamella is 
elongated vertically with its upper margin deepest, and 
separated by a narrow cleft from the dorsal, which fuses 
with the edge of the branchiz—the whole forming a broad 
flat blade. The bristles have the same structure. At the 
twentieth foot the vertical elongation of the ventral lobe is 
marked, and the lower half bears a row of hooks, which have 
a bold curve at the junction of the shaft with the neck, 
then slightly diminishes upward to the main fang, which 
makes more than a right angle with the neck, is long and 
sharp, with a spike above it, and has a wing on each side. 
The upper dorsal bristles are longer and more slender. At 
the fortieth foot the branchia is shorter and_ broader, 
and the upper group of the bristles much elongated and 
very finely tapered. The ventral hooks are similar. 
In 1896 Mesnil established the genus Nerinides for 
De St. Joseph’s Nerine longirostris, in which the pro- 
stomium was without frontal processes. The branchize 
extended from the second setigerous segment, and these 
sense hled 
