34 G. HERBERT FOWLER. 



Fig. 11. Longitudinal section of a partly expanded tentacle of Seria- 

 topora, showing the single battery of nematocysts, at the 

 tip, interspersed with a few deeply staining gland cells. 



Fig. 12. Diagram of a longitudinal section of an introverted tentacle 

 of Seriatopora. B. The battery of nematocysts, pointed 

 upwards. 



Fig. 13. Diagram of an ideal longitudinal section through a polyp 

 of Seriatopora, along the line a... a in Fig. 9. Of the six 

 tentacles, three are expanded and three are introverted, 

 one of the latter being cut longitudinally. Of the mesen- 

 teries, that on the right of the figure (10) is one of the 

 two longest ; that on the left (5) is much shorter ; while 6 

 and 7 are rudimentary, and do not reach as far as the end 

 of the stomatodseum. The cavity is divided into two 

 halves by fusion of the axial and abaxial into one median 

 septum. 



Fig. 14. Early stage in the development of spermatozoa inPocillopora. 



Fig. 15. Later stage of the same. The testis is surrounded on all 

 sides by endoderm, owing to the projection of the capsule 

 outwards from the plane of the mesentery (vide p. 28). 



Fig. 16. Transverse section through the calyx of Flabellum (vide 

 p. 30). The numbers ii., iii., iv., indicate the orders 

 to which the septa respectively belong. Other letters as 

 Fig. 4. 



Fig. 17. Transverse section through part of the pedicle of Flabellum, 

 showing the conversion of the embryonic theca into a 

 nearly solid pedicle, i., ii., Primary and secondary septa. 



