THE ANATOMY OF THE MADREPORARIA. 33 



Fig. 4. Transverse section of the calyx of Lophohelia prolifera near 

 the lip (vide p. 22). The darker parts represent " centres of 

 calcification," or the earliest deposited portions, which 

 become enlarged into the regions marked respectively T. 

 (thecal), or 8. (septal), according to their origin. The 

 regions are bounded by " sutures." Ed. s. Ectocoelic septa. 

 Ent. s. Entoccelic septum. 



Fig. 5. Similar section of Lophohelia prolifera at some distance from 

 the lip of the corallum. The " centres of calcification " of 

 the ectocoelic septa and of the theca have run into one line, 

 owing to the growth of the latter upwards to the former. 

 Lettering as in Fig. 4. 



Fig. 6. Diagrammatic transverse section through a segment of 

 Lophohelia prolifera. The septa are seen to stand in both 

 ectocoelic and entoccelic spaces. The peripheral sections of 

 these spaces and the peripheral lamellae of the mesenteries, 

 cut off by the upgrowth of the theca, are also apparent. 

 Lettering as in Fig. 2. 



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

 obtained by a longitudinal section of the polyp, cb. Caly- 

 coblasts. me. Mesogloea. en. Endoderm. 



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

 by a tranverse section of the polyp (vide p. 24), showing the 

 separation of a mesentery into central and peripheral parts 

 in process. Cod. Intrathecal coelenteron. Ccel'. Extra- 

 thecal coelenteron. M. The central, and M'. the peripheral 

 part of the mesentery. Others letters as before. (Cam. 

 Inc.) 



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

 subulata. 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 arc seen the pair of longer mesenteries, 3 and 10. 

 ((Jam. luc.) 



