PLATE XXXIV. 
PAGE 
Figs. 1-13. CoralUstes masoni, . . , . 303 
Figure 1. Sponge; nat. size. 
2-8. Spicules — 
Fig. 2. Dichotrisene ; x 63. 
,, 2a. Cladome, seen /ace; x 63. 
,, 3. A very yoimg form of desma ; x 73. 
,, 4. Another young form, more enlarged, 
showing the crepis ; x 180. 
Fig. 5. A stage further advanced ; x 180. 
,, 6. A stage stiU later ; x 73. 
„ 7, 8. Fully grown desmas ; x 73. 
9. Section through part of the choanosome, showing a strand of fusiform cells, the function 
of which is unknown ; x 225. 
„ 10. A part of the choanosome, showing flagellated chambers; x 225. 
„ 11. Epithelial surface seen on the walls of one of the canals; x 430. 
,, 12. Section through part of the cortex, showing vacuolar connective tissue; x 360. 
„ 13. Section at right angles to the surface of the sponge, showing the general appearance of the 
cortex : the clear oval spaces of uniform size are the vacuoles of the vacuolar connective 
tissue; x 95. 
Figs. 14-19. CoralUstes typusy ..... 301 
14. The sponge ; nat. size. 
15. The face of a section taken through a median vertical plane; nat. size. 
16. Section at right angles to the surface, showing the arrangement of the hard parts in the 
ectosome; x 125. 
17. One of the problematical hollow siliceous bodies (Diatoms?) strewn through the ectosome ; 
X 292. 
„ 18. Dichotrisene; x 63 ; fig. 18a, cladome of the preceding seen en face ; x 63. 
„ 19. Centrotylote microxea, which was observed as an adventitious form apparently resulting from 
the modification of a spiraster ; x 292. 
Figs. 20-22. Pacliymatisma johnstonia, .... 242 
„ 20. Part of figure 21, more highly magnified ; x 292. 
,, 21. Transverse section through one of the oscular canals of the cortex ; x 61. 
„ 22. The epithelium of an intercortical canal, seen /ace ; x 360. 
