Plate 47 



Fig. 1. Sidonops microspmosa. Pore area. One pore Dot completely closed. 

 Two dense groups of spherasters indicate closed pores. X140. 



2. Sidonops microspmosa. Oscular area with an open osculuni. Sphe- 



rasters densely crowded round osculuni. X85. 



3. Sidonops microspmosa. Oscular area with closed osculuni. Posi- 



tion of latter indicated by an accumulation of spherasters. X85. 



4. Geodinella spherastrosa. Reduced triaenes. a, b, c, monaenes with 



comparatively sharp vestigial clad in side view ; d, same with clad 

 showing in face view ; e, f, monaenes in which the vestigial clad 

 is reduced to a slight rounded protuberance shown in side view ; 

 g, h, completely degenerate spicules in which there is no sign of 

 a clad, the axial canal sending off no branch. X175. 



5. Geodinella spherastrosa. a, dermal spherasters ; b, strongylasters 



from cortical canals; c, oxyasters from choanosome. X600. 



6. Geodinella spherastrosa. Surface, showing sterraster-free pore areas, 



p. a. X45. 



7. Geodinella spherastrosa. Vertical section through cortex, ef. c. c, 



efferent chone canal opening above by an osculuni; end. c, closed 

 canal of endochone marked by a streak of strongylasters ; eh. e., 

 inner end of chone ; end., dense fibrous tissue of contracted endo- 

 chone ; f. c., fibrous collenchyma round chone canal ; s. c., wall of 

 subcortical canal. X45. 



8. Sidonops microspinosa. a, spherasters ; b, oxyasters from cortical 



canal; c, larger oxyasters from choanosome. X600. 



9. Donatia ingalli, var. seychellensis (E. P. Wright). From a radial 



section, f. s., fibrous stratum of ectosome ; n, skeletal " nucleus." 



X7y 2 . 



10. Donatia int/alli. var. seychellensis (E. P. Wright), a, spheraster 



X600; b, chiaster (acanthtylaster) X 1,000; c, ehoanosonial 



oxyaster X600. 



11. Jaspis serpentina, a, skeletal twisted rhabd, only terminal parts 



shown, X100; b, small oxea X300; c, chiaster (acanthtylaster) 



X 1,000; d, d', oxyasters X500. 



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