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PLATE XIII. 
PAGE 
Kgs.’ 1-29. Antliastr a communis, . . . .140 
Figure 1. Sponge; nat. size. 
„ 2-6. Spicules — 
Fig. 2. Oxea; x 32. Fig. 5. Anthaster; x 430. 
,, 3. Dichotrisene; x 32. ,, 6. Chiaster; x 430. 
,, 4. Anatrisene; x 32. 
7. Section through, the outer part of the ectosome ; x 200. 
8. Eadial section through a part of the choanosome, showing the relations of tiie excurrent 
and incurrent canals ; x 70. 
9. Section through a part of the choanosome, showing flagellated chambers, with their aphodi ; 
X 360. 
10. Cavity in the choanosome, left by the tearing away of a megasclere, showing the remains 
of the scleroblast ; x 292. 
11. Section through a part of the choanosome, showing anastomosing aphodi. 
12. Another sponge of the same species, originally regarded as distinct; nat. size. 
13. Two sponges of the same species united in growth ; nat. size. 
14-28. Spicules — 
Fig. 14. Oxea; x 32. 
,, 15. DichotriEene; x 32. 
„ 16. Early stage in the growth of the dicho- 
trisene; xl80. 
,, 17. A stage somewhat later; x 49. 
„ 18. A stage later still; x 49. 
Fig. 19. Cladal end of adult dichotrisene, with 
a cyathiform cladome; x 32. 
„ 20. Cladal end of a young form of ana- 
trisene; x 180. 
„ 21. Cladal end of adult anatrisene; x 32. 
,, 22-24. Anthasters; x 292. 
„ 25-28. Chiasters; x 430. 
29. Part of the rhabdome of a young anatrisene, showing the nuclear portion of the scleroblast ; 
X 292. 
t/ 
Figs. 30-40. AntTiastra parvispicula, . . . . . 145 
30. Sponge; nat. size. 
31-38. Spicules — 
Fig. 31. Oxea; x 49. 
,, 32. Orthotrisene; x 49. 
„ 33. Anatrisene; x 49. 
39, Section through ectosome and adjacent choanosome to show ihe passage of the subdermai 
cavities into the incurrent canals ; x 15. 
Fig. 34. Cladal end of anatrisene, more highly 
magnified; x 180. 
,, 35-37. Anthasters; x 430. 
,, 38. Chiaster; x 430. 
40. Section through the ectosome ; x 49. 
