PLATE XXXIL 
PAGE 
Figs. 1-11. Discodermia discifurca, . . . 292 
Figure 1. Sponge ; nat. size. 
„ 2. Section at right angles to the surface, showing the skeleton of the 
sponge with the phyllotrisenes in place, clothed by an incrusting 
Monaxonid ; x 63. 
„ 3. Section through part of the choanosome ; x 292. 
4-11. Spicules — ^ 
Figs. 4, 5. Tetracrepid desma ; x 86. 
„ 6. An abnormal form of desma, 
with only three epactines; 
X 86. 
Figs. 7-9. Different forms of phyllo- 
triaene ; x 86. 
„ 10. Microxea; x 292. 
„ 11. Microstrongyle ; x 292. 
Figs. 12-25. Discodermia panoplia, . . . 295 
„ 12. The sponge ; nat. size. 
,, 13-20. Spicules — 
Fig. 13. Tetracrepid desma; x 63. 
„ 14. A part of the desma more 
highly magnified, to show 
the character of the syzygial 
tubercles; x 125. 
„ 15-19. Discotrisenes; figs. 15-17, x 49; 
figs. 18, 19, X 63. 
Fig. 20. Discotrisenes of the superficial 
and immediately underlying 
layer from near the base of 
the sponge, showing the 
zygosis of the desmas of the 
latter layer ; x 125. 
21. Poral surface of the sponge, showing the poral sinuses of the 
discotrisenes ; x 37. 
22. A part of the oscular surface with the superficial discotrisenes 
removed, to show the nature of the rhabdal sinuses ; x 49. 
23. Oscular surface ; x 37. 
24. A fragment of skeleton from a cavity in the limestone on which the 
sponge is attached, to show the modifications undergone by the 
syzygial tubercles, which have become flattened and laminar ; 
X 63. 
■v: 
5 ? 
25. A young discotrisene ; x 63. 
