PLATE L 
Figs, 1-15. Tetilla le'ptoderma, 
Figure 1. Sponge ; nat. size. 
„ 2-11. Spicules — 
Fig. 
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3 
7. Somal anatris&ne ; x 125. 
„ 8. Sigmaspires ; x 290. 
„ 9. Cladome of protrisene ; x 
180. 
„ 10, 11. Trichodal protrieenes, parts 
of; X 290. 
Fig. 2. Oxea of the radial spicular fibres; 
X 20. 
„ 3. Protriaene;, x 20. 
„ 4. Somal anatrisene ; x 20. 
„ 5. Oxea, not forming spicular fibre ; 
X 20, 
„ 6. Eadical anatriaene ; x 180. 
„ 12. Transverse section taken through a pore-sieve, and the adjacent 
tissues ; X 125, 
„ 13, Section through part of the choanosome ; x 125. 
„ 14, Transverse section of a part of the sponge; x 11. 
„ 15. A part of the preceding ; x 34, 
Figs. 16-27. Tetilla sandalina, 
,, 16. Sponge; nat. size. 
„ 17. Two flagellated chambers ; x 300. 
,, 18. A vertical longitudinal section through the sponge ; x 4 '5, 
,, 19. Choanocyfes ; x 430. 
„ 20-25. Spicules — 
Fig. 20. Oxea; x 50. 
„ 21. Protriaene; x 60. 
„ 22. Sigmaspires; x 360. 
„ 23-25. The cladome of the pro- 
„ 26. Section of a part of the choanosome ; x 180. 
„ 27. Section of a part of the ectosome, showing flagellated chambers 
situated immediately beneath the outer skin ; x 180. 
Figs. 28-35. Craniella carteri, 
„ 28. Sponge ; nat. size. 
„ 29-33. Spicules — 
Fig. 29. Somal oxea; ; x 41. Fig. 32. Cladome of protriaene; x 
„ 30. Anatriaene; x 40. 180. 
„ 31. Protriaene; x 40. „ 33. Cladome of anatriaene; x 180. 
„ 34. Transverse section through the cortex and adjacent choanosome ; 
X 15. 
„ 35. Part of the preceding more highly magnified, showing one of the 
dermal glands ; x 290. 
triaene and its modifications; fig. 23, 
heterocladal protriaene; fig. 24, 
heterocladal prodiaene ; fig. 25, pro- 
monaene; x 180. 
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