828 ARTHUR WILLEY. 
4. Gastro-vascular System.—The central main portion 
of the gastro-vascular system presents the lobed appearance 
shown in the figures, the lobes being paired about the tentacle 
axis. The middle and largest pair of lobes belong to the 
stomach, and thus serve to mark out the stomachal plane 
(Magenebene of Chun). The stomachal plane, therefore, as in 
the Ctenophores, lies at right angles to the plane of the ten- 
tacles, which corresponds to the funnel plane (Trichterebene) 
of Ctenophores. 
My identification of the stomachal plane in Ctenoplana is 
just the reverse of Korotneff’s, who erroneously placed it in 
the true tentacular plane. 
From the two opposed sides of the stomach a narrow median 
canal leads into the two terminal end-lobes of the central 
gastric cavity (cf. the schematic fig. 11). The two end- 
lobes are in open communication with the peripheral canal- 
system. 
I do not find such definitely circumscribed peripheral canals 
as those figured by Korotneff, but they appear to me in section 
merely as the spaces partitioned off by the dorso-ventral 
trabeculee, which Korotneff describes as dorso-ventral muscles 
(fig. 5). 
The median funnel-vessel was correctly figured by Korotneff. 
It arises from the stomach immediately opposite to the 
mouth, and, proceeding aborally, embraces the sense-organ 
without opening to the exterior. It is very clearly shown in 
section. 
5. Tentacle Sheaths and Musculature.—The tentacle- 
axis is occupied by the sheaths of the tentacles, which are 
hollow tubes lined by ciliated cells lying immediately beneath 
the dorsal surface, and completely separated from one another 
by the aboral sensory complex. The muscles of the tentacles 
form part of the voluminous musculature, which, so far as I 
can make out, effects the retraction of the aboral sense-organ 
and of the ctenophoral plates, which can be completely with- 
drawn into the body (ef. fig. 5). The tentacles were retracted 
in my preserved specimens, and so it was impossible for me to 
