224 PERCY SL^^lDEN TRUST EXPEDITION 



Fig. 19 e. A single polyp as it appears when removed from the sponge, x 3. 



Fig. 19/. Two polyps enclosed in the same collar (col.), x 3. 



Fig. 19 g. Side view of collar {col.) enclosing polyp, x 3. 



Figs. 20, 21, 22. Stout dermal hexacts, from collar around polyp, x 175. 



Figs. 23, 24, 25. Sarulce, from collar around polyp, x 175. 



Fig. 26. Gastral hexact, from central cavity of skeletal framework, x 175. 



Fig. 27. Spiny parenchymal hexact. x 175. 



Figs. 28, 29, 30. Oxyhexasters. x 540. 



Fig. 31. Discohexaster. x 540. 



Plate 43. 

 Figs. 32 — 36. Sarostegia oculata Topsent. 



Fig. 32. Uncinate, x 102. 



Fig. 33. Part of dictyonal framework as seen in longitudinal section through end of branch, x 60. 



Fig. 34. Part of dictyonal framework as seen in tangential section just below surface, x 175. 



Fig. 35. Skeleton surrounding central cavity, as seen in transverse section near tip of young branch. 



x60. 



c.c. central cavity ; hex. hexacts ; pr. spiny processes of trabeculse. 

 Fig. 36. Skeleton surrounding central cavity, as seen in transverse section, to show the union of spiny 



processes (pr.) to form a new node of the network, x 60. 



