PLATE V. 
Figs, 1-14. Tetilla grandis , .... 
Figure 1. Sponge, with basal mass of spicules ; nat. size. 
„ 2. Young sponge, without a basal mass ; nat. size. 
,, 3. Tetilla grandis, var. alba, sponge ; nat. size. 
„ 4. Section through a young specimen ; x 9 '5. 
,, 5. Eadial section through the cortex of the adult sponge, showing the 
cavernous vesicular tissue ; x 292. 
„ 6a. Section through a part of the cortex, showing the cladal end of an 
anatriaene, with the nuclei of associated cells forming a series 
along its sides ; x 292. 
„ 6-14. Spicules — 
Fig. 6. The cladal end of a normal ana- 
trisene; X 180. 
„ 7. The cladal end of a young form of 
anatriaene; x 292, 
„ 8. The cladal end of an anatrisene, in 
which therhahdomeis continued 
distally past the cladal origin ; 
X 292. 
„ 9. The cladal end of an anadisene 
presenting the same feature; 
X 292. 
Fig. 10. The cladal end of a young 
prodisene, showing the tylus; 
X 292. 
„ 11. The cladal end of a young 
form of protrisene. 
„ 12. The cladal end of a protrisene, 
in which the cladi show a 
tendency to branch; x 292. 
„ 13. The end of a rhahdus, with an 
accessory cladus; x 292. 
14. The end of a rhahdus with 
several accidental branches. 
Fig. 15. Craniella simillima, 
15. The cladal end of a young trisene, before the appearance of cladi, 
showing the tylus ; x 576. 
Fig. 16. Craniella cranium, 
16. The cladal end of an anatrisene, in which a second cladome has 
developed ; x 292. 
Figs. 17, 18, Poecillastra tenuilaminaris, 
17. Sponge; nat. size. 
18. Longitudinal transverse section, showing the thickness of the wall ; nat. 
PAGE 
10 
30 
51 
85 
size. 
