A CONTRIBUTION TO THE ANNELIDA. 67 
segment had a ventral band of cilia, whereas none occurred on 
the dorsum. The terminal segment had a ring of long cilia. 
The alimentary canal was roseate. This larva is distinguished, 
he says, from a Leucodore larva by the dilated anterior end, 
by the brownish pigment-touches, the smooth bristles, by the 
veutral cilia on all the segments, and by their absence on the 
dorsal surface. 
It exhibits by-and-by a modification of the head, which 
becomes elongate heart-shaped, and by the development of 
lateral papillee from which the tentacles grow behind the eyes. 
The provisional swimming apparatus, viz. the bands on the 
head, the lateral tufts, the ventral bands, and the anal ring are 
all increased. 
When it reaches the length of about 2 mm. it approaches 
a Spio larva, and swims freely in the water by a rapid 
wriggling of the body. The heart-shaped snout is narrowed in 
front, concave below, and convex above. The four reddish 
eyes are larger, and the middle pair placed in advance. The 
first body-segment overlaps the head, and from its sides spring 
the short tentacles, which are borne like a pair of horns, the 
inner side of each being marked by brownish parallel striz, 
and the slender papille are 0°017 mm. long. The tentacle has 
a central blood-vessel which ends blindly, and its blood con- 
tains corpuscles. The first segment bears the huge bristles, 
while the last is elongated, cylindrical, and is devoid of bristles. 
The rows of hooks occur from the ninth segment, some of 
them in sacs. They are more numerous posteriorly (to the 
number of fifteen). The posterior end is pointed and bears 
small, colourless, pyriform (birnformige) papille. The diges- 
tive canal begins with an oval mouth and a muscular proboscis, 
which has a pair of opaque (brownish) glands at its posterior 
end. The canal, which is constricted in front, dilates at this 
point. The colour of the larva is delicate brownish, with 
parallel bands of the same hue on the tentacles ; longitudinal 
and transverse brownish touches on the snout. The trans- 
lucent anterior region and the three following segments bear 
similar touches. The middle fifteen segments of the body have 
