PLATE XXXI. 
PAGE 
Figs, 1-6. Discodermia ornata, ’ . . 297 
Figure 1. Skeleton of the sponge ; nat. size. 
„ 2-6. Spicules — 
Figs. 2, 2a. Oxeas; x 95. 
„ 3, 3a, 3b. Microxeas ; 3a, centrocli- 
nate ; 3b, centrotylote ; x 360. 
„ 4. Microstrongyles ; x 360. 
„ 5, 5a-5d. Discotriaenes ; x 95. 
Figs. 6, 6o-6c. Tetracrepiddesmas; fig. 
66 stows on the right the 
character of the zygosis ; fig. 
6c shows a tetraradiate cavity 
produced by an enlargement of 
the canal of the crepis; x 73. 
Figs. 7-12. Neosiphoma superstes, . . . 299 
,, 7, 7a, 7b. The sponge; figs. 7 and 7h seen from opposite sides, 7a, from 
• above ; nat. size. 
8-12. Spicules — 
Fig. 8. Oxea; x 38. 
„ 9, 9a. Spirasters; x 360. 
„ 10. Dichotrisene ; x 95. 
„ 10a, Trichotriaene ; x 95. 
Figs. 11, 11a. The desma; fig. 11 seen 
by reflected light; x 73. 
„ 12, 12a. Examples of the mode 
of zygosis; x 150. 
