184 BULLETIN OF THE 
special pigment spots of the head which are called ocelli. The original 
‘pigment dots” (/) lie in the third body segment. The point of separation 
between the stomach and cesophagus is near the seventh and eighth body seg- 
ments. The formerly enclosed anal ring of green color and the two regions 
of green pigment on the last body segment have coalesced, so that the whole 
terminal segment has the same yellow and green color as the head. The intes- 
tine is slightly tortuous in its course, and is clearly differentiated from the 
stomach. Scattered red pigment spots appear on the external body walls along 
the dorsal and ventral median lines. 
The oldest worm in the series described above was raised from the youngest 
through the successive stages mentioned. Although the larve as a rule bear 
confinement with little discomfort, I was never able to raise them into the 
adult Nephthys. 
The identification of the larve of a related species by Claparéde and Metschni- 
koff has been followed, since three forms of the larvee which are here figured will 
be found to resemble “stages” which they have already represented. The old- 
est larva which was studied ismuch more developed than the oldest which they 
had, and approaches the adult form more closely, which seems to me to add new 
evidence to confirm the identification which they made. Until, however, it is 
raised into an adult, or the youngest is traced back to the mother through the 
egg, the identification must be regarded as provisional. The homology of 
the black spots originally found on the apex of the preoral lobe, but now in 
the fourth body segment, is doubtful. The theory that they are homologous 
with the embryonic otoliths of Terebella, has little to recommend it. It is 
not known whether they are lost in later growth in older larve or not. 
Claparéde and Metschnikoff speak of these “ eye-spots ” as eyes with lenses, 
and the neighboring transparent “ cells” as brain lobes. In the oldest larva 
which they represent in their figures (Pl. XIV. Fig. 3, c) these bodies are 
situated in the head. In the oldest larva which is described in the present 
paper, they lie in the fourth body segment. Similar bodies have been figured 
by Bobretsky * in the larve of Pholoé. 
The movement of the “eye-spots” from the head into the fourth body seg- 
ment is probably brought about by the growth forward of the head and the 
anterior body segments. The means by which this has been accomplished is 
not, however, perfectly clear. 
* Kb MCTOPIM PASBUTIA AHHEJIMIB, Pl. IX. Figs. 8, 4. The copy 
of this paper which I have used is from Zapiski Kiefskavo Obshto Yestestvois- 
pitatalyei. 
