PLATE XXL 
Figs. 1-14. Cydonium magellani. 
Figure 1. Sponge, attached to a small example of Astrella vosmaeri : nat. size. 
2-8. Spicules — 
Pig. 2. Oxea ; x 29. 
,, 3. Dichotriasne ; x 29. 
,, 4. Cladal end of a dicliotrisene with a more 
cyathiform cladome ; x 32. 
Fig. 5. Anatrisene ; x 29. 
,, 6. Sterraster; x 7-5. 
,, 7. Somal strongylate spheraster ; x 430. 
‘ „ 8. Choanosomal oxyaster ; x 430. 
9. Median longitudinal section through a chone ; x 35. 
10. Tangential section through a part of the ectochrote ; x 292. 
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223 
11. Oblique tangential section, passing through the inner face of the cortex and the adjacent 
choanosome ; the sphincters of two chones are seen as darkly stained rings ; x 22. 
12. Section through part of the choanosome, showing a flagellated chamber and surrounding 
sarcencytes; x 292. 
13. Transverse section across the myocytes of a chonal sphincter ; x 540. 
14. Transverse section through the cortex, showing the hispidation produced by the oxeas and 
trisenes ; x 1 1 . 
Figs. 15-29. Cydoviwm eosaafer, .... 225 
15. Sponge; nat. size. 
16-26. Spicules — 
Fig. 16. Oxea ; x 32. 
,, 17. Cladal end of dichotriaiiie ; x 32. 
„ 18. Cladal end of anatri»ne ; x 73. 
,, 19. Cladal end of anatrisene ; x 32. Drawn 
to same scale as fig. 17 for comparison. 
,, 20. Cladal end of protrisne ; x 32. 
,, 21. Sterraster ; x 73. 
27. Transverse section through the sponge, showing the continuation of the chonal canals 
inwards, till they communicate with a deep lying concentric canal; x 11. 
28. Section through the sponge, taken on one side of the medial plane ; x 1 1 . 
29. Section taken longitudinally through the middle of a chone ; x 73. 
Fig. 22. Spheraster ; x 73. 
,, 23. Spheraster ; x 292. 
, , 24. Somal spheraster ; x 360. 
,, 25. Choanosomal oxyaster ; x 360. 
,, 26. Choanosomal oxyaster, another ex- 
ample ; X 360. 
Figs. 30-42. Cydonium hirsuhis, 
30. Part of the sponge ; nat. size. 
31. Transverse section, showing the unusually thick cortex and cavernous choanosome; nat. 
size. 
32-42. Spicules — 
Fig. 32. Oxea ; x 28. 
„ 33. An oxea, not proper to the sponge ; x 73. 
„ 34. Cladal end of dichotrisene ; x 28. 
,, 35. Sterraster, presenting the face bearing 
the hilum ; x 28. 
,, 36. The same, seen from the side at right 
angles to that bearing the hilum ; 
X 28. 
,, 37. Surface of the sterraster ; x 540. 
,, 38. Part of a transverse section, showing the 
two actines of the sterraster with 
intervening spicular substance, the 
axial rods of the actines are also 
shown ; x 430. 
Fig. 39. Tangential section of the sterraster, 
taken through the actines at a level 
exterior to that at which they be- 
come soldered together ; x 540. 
,, 40. Section transverse to the actines, taken 
deeper in ; x 430. 
, , 41. Cortical spheraster ; x 312. 
,, 42. Somal spheraster ; x 430. 
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