NERINIDES LONGIROSTRIS. 479 
Habitat.—Dublin, Clew and Blacksod Bays, in sand under stones (Southern) ; shores of 
France, at St. Martin (Mesnil). 
This is a much larger form than Spio Gattyt, and the aspect differs. The head is character- 
istically 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 branchie, and the ventral surface being marked anteriorly by 
lines of dark pigment on the tumid region behind the mouth, and with a dark line in the 
middle of each segment-junction for ten or twelve segments. 
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 differing 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 bristles finely tapered but less curved distally. At the tenth 
foot (Plate CXXXVIII, fig. 3) 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 branchia, the whole forming a broad, flat blade. The bristles have the same 
structure. At the twentieth foot (Plate CXX XVIII, fig. 3a) the vertical elongation of the 
ventral lobe is marked, and the lower half bears a row of hooks each of which has 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. 
Genus NERINIDES, Mesnil, 1896. 
Prostomium without frontal processes. Branchiz from the second setigerous segment ; 
dorsal lamella longer than the branchie; the ventral division of the foot has no hollow. 
No hooked dorsal bristles ; anal sucker. 
NERINIDES LONGIROSTRIS, De Quatrefages, 1848. Plate CXXXIIT, figs. 18—18b—bristles 
and hook; Plate CXX XVI, fig. 6—foot, 6a—dorsal bristle. 
Specific Characters.—Head acutely pointed, with a median ridge which runs backward 
to the third segment, and bears four eyes nearly in a square. Two golden yellow and rather 
short tentacles with a ciliated dorsal groove. Body 10 cm. long and 8 mm. broad, tapered 
a little anteriorly, more distinctly diminished posteriorly and having the general aspect of 
