80 
13: 
MORGAN. 
PLATE Lu: 
Fig. 1-5: Stage I. Fig. 6-15: Stage II. Fig. 16-22: Stage III. 
Section of tentacle. Zezss, 2 D. 
Section of circum-oral region. Zeiss, 4 D. 
Surface view, stomach and first body-cavity, taken from cross-sections. 
Cross-section of anterior wall of stomach. 
Cross-section of oesophagus. 
(Stage II.) Longit. section of lateral body-wall. 
Surface view of left side of apical plate. 
Cross-section of stomach and ectodermal tube. 
Cross-section of stomach and opening ectodermal tube. 
Cross-section of body; youngest stage proboscis vesicle. 
Cross-section of body ; older stage proboscis vesicle. 
Cross-section of body; next section to last. 
Cross-section of body; through third body-cavity and circular band. 
14 a-b. Cross-section of body; to show origin of third body-cavity. 
Els 
17s 
18. 
10. 
20. 
oT 
22. 
Left side. 
. 15 a-hk. Cross-section of body; to show origin of third body-cavity. 
Right side. 
(Stage III.) Surface view of extra-oral area. Zezss, 2 D 
Surface view of circum-oral area. Ze7zss, 2 D. 
Cross-section of tentacle. 
Surface view of apical plate. 
Surface view of eye. Zezss, 2 F. 
Optical section of eye. Zetss, 2 F. 
Actual section of eye. Zezss, 2 F. 
