336 ARTHUR WILLEY. 
tures as the proboscis of Nemertines and of certain Rhabdocele 
Planariauns. 
Finally, we may recapitulate the organs in Ctenoplana which 
are paired about the tentacle axis (cf. fig. 1). There are four 
pairs of ctenophoral plates, three pairs of gastric lobes, two 
pairs of gonads with their ducts, and one pair of multiple 
sensory tentacles. 
From what has been said I regard it as proved that— 
1. The tentacle axis of Ctenoplana = the longitudinal axis of Planarians. 
2. The stomachal axis of Ctenoplana = the transverse axis of Planarians. 
3. The main axis of Ctenoplana = according to Lang, the primary main 
axis of Planarians, which becomes bent as the ganglion is shifted 
towards the anterior end of the body. 
4. The main axis of Ctenoplana and Ctenophores = the dorso-ventral axis 
of Bilateralia. 
8. Synopsis of Species of Ctenoplana. 
(i) C. Kowalevskii, Korotneff—Colour crimson, body in 
swimming attitude shaped like a truncated pyramid ; median 
dorsal surface concave ; free margin of skirt frilled. Habitat, 
west coast of Sumatra. 
(ii) C. rosacea, n. sp.—Colour crimson; body in swim- 
ming attitude of a quadrilateral form; median dorsal surface 
convex; free margin of skirt plain. May be merely a variety 
of preceding species. Habitat, Eastern Archipelago of New 
Guinea. 
(iii) C. Korotneffi, n. sp.—Colour green; body in swim- 
ming attitude roof-shaped; median dorsal surface upraised 
with two upright end-knobs; free margin of skirt slightly 
frilled. Habitat, Hastern Archipelago of New Guinea. 
In Korotneff’s fig. 13 there are only eleven sensory ten- 
tacles figured for C. Kowalevskii,! while C. rosacea had 
1 Korotneff describes an aperture to the exterior on each side in the 
neighbourhood of the tentacles in C. Kowalevskii which leads into a 
“system of canals which branch in the body parenchyma.” Korotneff him- 
self says that after he had preserved his specimen in sublimate he was unable 
properly to orientate it. I have already shown that he completely misplaced 
the tentacles. The apertures in question are obviously the openings of the 
