PLATE IX. 
Figure 
33 
33 
33 
33 
33 
Pcecillastra schuhii,^ 
1. Sponge ; nat. size. 
■22. Spicules-^ — 
Figs. 2, 3. Oxeas; x 40. 
„ 4. Ortliotrieene ; x 51. 
„ 5. Caltliropsj x 51. 
„ 6. Microxea; x 51. 
„ 7. Metaster; x 51. 
„ 8-13. Metasters ; x 360. 
„ 14, 15. Spirasters ; x 360. 
Fig. 16. Modification of tlie ortho- 
triaene; x 51. 
„ 17, 18. Eeductions of the calthrops; 
X 51. 
„ 19-21. Microxeas; x 292. 
„ 22. Eeduced cal throps, approach- 
ing an oxea; X 51. 
23. Superficial tangential section through . the ectosome, showing the 
irregularly branching subdermal cavities; x 18. 
24, Tangential section through the endosome or hypophare ; x 18. 
25, Part of a section through the choanosome, showing one of the large 
problematical cells ; x 430. 
26. Transverse section through the sponge-plate ; x 11. 
27. Part of a section through the choanosome, showing the continuity of 
collencytes with choanocytes ; x 360. 
28. Two spongin bodies seated on a large oxea, one of them surrounding a 
second smaller oxea ; x 292. 
29. Part of a section through the choanosome, showing the eurypylous 
chambers, granule-cells, and a small example of the large problem- 
atical cells ; X 180. 
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^ It has been found necessary to change the generic name since the Plate was printed off. 
