REPORT ON CORALS — EXPLANATION OF PLATES. 247 



by a series of transverse bars, between which lie more or less reniform 

 depressions. The bottoms of these reniform depressions are traversed in their 

 centres by the under edge of a septum, on either side of which is an oval 

 perforation. 



Fig. '6. The same. Portion of the upper surface of the wall of the corallum near its 

 margin to show the arrangements of the perforations. Two series of per- 

 forations are shown. The perforations are disposed in pairs on either side of 

 each septum. At the bottom of the figure the commencement of two septa 

 are shown. The wall is folded, so as to rise on either hand towards the lines 

 of origin of the septa, thus forming a series of low ridge-like elevations, 

 separated by corresponding lines of depression or valleys, the bottoms of which 

 correspond with the costa?. 



Fig. 7. The same. Diagrammatic representation of one of the septa seen from its side to 

 show the arrangement on the septal margin of the paliform spines, and the 

 indented lower border of septum. The indentations correspond in position 

 with the depressions seen in fig. 5. 



Fig. 8. Stephanophyllia formotissima. The coral with the soft parts in situ to show the 

 arrangement of the tentacles. On the right hand side the primary (1) and 

 secondary (2) septa are indicated by lines to show the position of the tentacles 

 with regard to them. Enlarged 2 diameters. 



Fig. 9. The same. Vertical section through the soft parts of a decalcified specimen. 



A. A. Apertures in the basal tissue, through which passed in the living 



state of the coral the transverse bars of the perforated wall of the 

 corallum. 



B. B. Apertures in the mesenteries. 



C. Spongy mass of soft tissue covering the columella. 



D. (Esophagus. 



S. Stomach-cavity bounded by the edges of the mesenteries, each 

 bearing mesenterial filaments. 



E. Principal or primary mesentery, showing the arrangement of mus- 



cular fibres upon it. 

 0, 0. Ova. 

 Fig. 10. Diagrammatic representation of the mutual arrangement of the hard and soft 

 parts in Flabellwn, as seen in a section of a portion of it cut transversely 

 to the vertical axis. The several layers are indicated by the shading 

 throughout, the corallum being represented as black ; E. Ectoderm ; EN. 

 Endoderm ; B. Mesoderm ; W. Wall of the corallum ; S, S. Septa ; M, M. 

 Mesenteries ; A, A. Muscles of the mesenteries ; MF. Mesenterial filaments ; 

 T. A. tentacle. 



