182 BULLETIN OF THE 
on, and new segments have been interposed between the ciliated ridge and the 
anal pole. A pair of pigment spots (/) resembling ocelli, or “ eye-dots,” appear 
in the dorsal walls of the preeoral lobe. The general appearance of this larva 
from the ventral side is characteristic. The preoral lobe is no longer hemi- 
spherical, but the elevation of the pole and the formation of a circular ridge or 
zone a short distance above the ciliated equator imparts to it a characteristic 
shape. The rounded projection or polar elevation of the proral lobe above 
this zone is crowned by a cluster or tuft of cilia. A black spot is found 
on each side of a median dorsal line passing to the apex of this protuberance. 
The green zone which was formed in the cephalic region of Fig. 2, while the 
preoral lobe had a regular hemispherical shape, has now increased in width, 
and the wall in which it lies bulges out, forming a collar about the lobe. 
This collar has a more greenish color than the rest of the larva. About its 
lower rim, however, there is considerable black and some red pigment. The 
mouth lies near the equator, situated similarly to that of the young Polygordius 
(“ Loven’s larva”), between two rows of cilia. 
The most important change which results in passing from that represented 
in Fig. 4 into the next oldest Nephthys (Fig. 5) is a still further elongation of 
the body, and consequent diminution in size of the preoral lobe. The most 
important addition is the formation of the parapodia, the spines (Fig. 6, b) of 
which even in this early stage are serrated, like those of the known species 
of Nephthys. The number of body segments is nine. Each parapodium (Fig. 
12, b) has a dorsal and ventral cirrus, and bears two bundles of sete, each 
composed of several short, serrated spines. The form of the stomach and 
intestine is more elongated than in the earlier larve. 
A larva a little older (Fig. 6) than that last described, although not unlike it 
in general contour, differs considerably from it in some particulars. This dif- 
ference is a result of changes which have taken place in the internal organs. 
On looking at the larva from the ventral side, the mouth can be seen just 
below the equatorial ring of cilia. Behind the mouth through the body walls 
appears the cesophagus, which when seen from the ventral side has a circular 
profile. Below the mouth, extending to the region of the seventh body seg- 
ment, is the stomach. At this point (seventh segment) the intestine begins, 
and from it is continued into the terminal body segment. Just below the 
junction of the esophagus and stomach, on the right-hand side of the figure 
representing a larva of this age seen from the ventral side, there will be no- 
ticed an indentation in the stomach walls, forming by the enlargement a space 
in the body cavity, in which lies a globular sac. The pulsations of the sac in 
this and subsequent larvee can be plainly seen through the body walls. The 
terminal body segment ends bluntly in two lateral prominences, which are 
colored green. In the median line between them on the dorsal side there is a 
small unpaired appendage, which persists in subsequent stages into the oldest 
larva of Nephthys which was studied. 
Fig. 7 represents a larva of Nephthys still older than the last. The whole 
larva, more especially the body region helow the circle of cilia, has become 
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