ANATOMY OF THE MADEEPOEARIA. 19 



Fig. 7-— Tissue from the growing edge of a septum of Lophohelia, ob- 

 tained by a longitudinal section of the polyp, cb. Calicoblasts. me. Meso- 

 glcea. en. Endoderm. 



Fig. 8. — Tissue surrounding a thecal centre of calcification, obtained by a 

 transverse section of the polyp (vide p. 9), showing the separation of a 

 mesentery into central and peripheral parts in process. Ccel. Intrathecal 

 ccelenteron. CorI'. Extrathecal coelenteron. M. The central, and M'. the peri- 

 pheral part of the mesentery. Other letters as before. (Cam. luc.) 



Fig. 9. Transverse diagrammatic section of a polyp of Seriatopora sub- 

 ulata. The mesenteries are numbered 1 — 12, in the same manner as the 

 Madreporse before described (3). Letters as in Fig. 2. (This diagram is 

 also good for Pocillopora.) 



Fig. 10. — View of a polyp of Seriatopora from above. The clearer spaces 

 in the body wall of the colony represent the positions of the echinulations on 

 which the body wall is supported, they having been dissolved away by acid. 

 Through the body wall are seen the pair of longer mesenteries, 3 and 10. 

 (Cam. luc.) 



Fig. 11. Longitudinal section of a partly expanded tentacle of Seriatopora, 

 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 Seriato- 

 pora, 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 

 mesenteries, that on the right of the fig. (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 stomatodaeum. 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 in Pocillopora. 



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. 14). 



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

 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. 



