248 THE VOYAGE OF H.M.S. CHALLENGER. 
Fie. 11. Flabellum alabastrum. Soft parts seen in a vertical section of one lateral half 
of the coral. 
M. Mouth leading to the stomach. 1, 2, 3 Mesenteries of those orders, 
with their attached filaments, muscles, and ova. The positions of 
the margins of the septa of those orders are represented by fine curved 
dark lines. The wall of the corallum is seen in section i situ. 
Fig. 12, Arrangement of the tentacles with regard to the septa in Mlabellum japoniewm. 
1, 2, 3, 4 Primary, secondary, tertiary, and quarternary septa, at the inner 
margins of which are seen the corresponding peculiarly-shaped tentacles, 
