EXPLANATION OF PLATE XV. 
Figs. 1 - 4. Goniopora fruticosa, S.-Kcnt. 1 — Corallum with a portion of 
the polyps extended, natural size, 2 and 3 — Horizontal and 
profile aspects of a single polype, enlarged 2 diameters. 4 — 
Single ealicle of corallum enlarged. 
Figs 5-8. Alvcopora spongiosa , Dana. 5 — Corallum with polypes ex- 
tended, natural size. 6 and 7 - Horizontal and profile aspects 
of a single polype, enlarged 2 diameters. 8— Superficial 
aspect of a few adjacent calicles, showing spinous septal 
elements, enlarged. 
