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J. I). F. GILCHRIST. 
on the right side. In the 67th section (PI. 14, fig. 30) both 
pairs of body cavities have disappeared. At the 95th section 
(PI. 14, fig. 31) the yolk mass is much smaller, and the ecto- 
derm has the clear spaces and the elongate cells characteristic 
of the dorsal and ventral parts of this region of the body 
respectively. 
The formation of the definite body cavity of the proboscis 
was not seen in these transverse sections, but in some longi- 
tudinal sections a division appeared running obliquely across 
the cavity of the archenteron anteriorly, and cutting off a 
portion of this cavity, the portion cut off being about one- 
fourth of the whole archenteron. This division was observed 
in two longitudinal sections only, and in these the thin wall 
of the archenteron was incomplete in places (PI. 14, fig. 37). 
How this division arose is not quite clear, and the 
question is perhaps better left open till further confirmation 
is possible. 
(3) Appearance of the anus in the larva. — In a 
sagittal section (PI. 14, fig. 38) of a larva the cavity of the 
archenteron extends to the posterior end, and comes in contact 
with the ectoderm. At the point of contact there is a slight 
involution and indication of a pore, though there is no well- 
marked opening. There seems little reason to doubt that this 
is the point of origin of the anus. In the section it is situated 
towards the dorsal aspect of the body. It doubtless, there- 
fore, represents the point at which the yolk mass remains in 
contact with the ectoderm, but has no connection with 
what is described later as a postero-ventral thickening und 
involution of the ectoderm. The section, however, was not 
entirely convincing, and later stages are desirable to clear 
up and confirm this point. There is no indication of the anal 
opening in PI. 14, fig. 22, a transverse section posterior to 
yolk and archenteron. 
(4) Changes in the sense organ appear in the larva. 
In the earlier stages it consisted of a group of elongate 
ciliated cells, at the base of which appeared a small patch of 
nervous tissue, as described for other species. In the more 
