PLATE 29. 



Porpita pacifica. 



Fig. 1. Radial section through the tentacuhir zone, and margin of the centradcnia. All but the 

 e.xtrenie margin of the pneumatophore has been stripped off; C. Ra, descending radial canals; C. T, 

 canals of the tentacular zone; C. S, superior canals of the centradenia (Ce); T', young, T^, older 

 tentacle; Go, gonozooid. From a dissection. X 20. 



Fig. 2. Radial section. Margin of tentacular zone, centradenia and pneumatophore; Li, limbus; 

 Ch. c, circular chamber. Other lettering as in fig. 1. From a ])hotograph. X 40. 



Fig. 3. Similar section, showing communication between the lumen of a young tentacle (Te) and 

 tentacular canals (C. E). From a photograph. X 40. 

 Section through the centradenia. X 30. 



Centre of the floor of the central gastrozooid, from below. X 40. 

 Section through lower part of centradenia; C. I, inferior canals. From a jihotograph. 



Section through centradenia, showing superior (C. S) and inferior (C. I) canals. From 



X30. 

 Similar section, showing connection between gonophore (Go) and inferior canals; Ch. C, 

 circular chambers of the pneumatophore; C. S, superior canals. From a photograph. X 20. 



Fig. 9. Section through margin of central gastrozooid, showing its connection with one of the 

 outer series of the centradenia canals (C. ). From a photograph. X 40. 



Fig. 10. Similar section, .showing the opening of one of the canals of the inner series (C. I); Go, 

 gonozooid. From a photograph. X 40. 



Fig. 11. Section through the base of gonozooid (Go), to show its connection with one of the 

 inferior canals of the centradenia (C. I). X 40. 



Fig. 12. Section through the upper wall of a superior centradenial canal, and of the overlying 

 pneumatosaccus. Ch. C, chitinous lower wall of the pneumatocyst; Ec-, ectoderm of pneumatosaccus; 

 SI, stutzlamella; En, entoderm of superior canal. X 250. 



Fig. 13. Transverse section of one of the lowest inferior canals; En, entoderm lining the canal; 

 Ec, ectoderm of the lower surface of the corm; Cr, guanin crystals. X 250. 



Fig. 14. Section through wall of inferior canal at intermediate level; Ec, ectoderm-parenchyma. 

 X250. 



