PLATE X. 
Figure 1. Sponge; nat, size. 
Figs. 1-12. Epallax callocyathus, 
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423 
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55 
2-9. Spicules — 
Fig. 2. Hispidating oxea; x 22. 
,, 3. Axial oxea; x 18. 
,, 4. Tylostyle, resulting from a reduction of 
the axial oxea; x 22. 
,, 5. Strongyle, similarly produced; x 22. 
Fig. 6. Oxyasters ; a, diactinate (microxea); h, 
microtriod ; c, tetractinate form ; d, 
microcalthrops; x 225. 
,, 7. Sphere, also resulting from the reduction 
of the oxea; x 22. 
,, 8. Group of coalesced spheres; x 22. 
,, 9. The same; x 125. 
10. Vertical longitudinal section through the wall of the sponge; x 9. 
11. Part of the choanosome of the preceding, more highly magnified ; x 180. 
12. The same, still more highly magnified ; x 229. 
Figs. 13-15. SpTiinctrella crihrifera, . . . .87 
Calthropella simplex, .... 107 
13. Both sponges ; nat. size, a, SpMnctrella crihrifera; h, Calthropella simplex. 
14. Vertical section through hoth sponges, and a third sponge — Astropeplus pulcher; a and 
6 as in the preceding figure ; c. Astropeplus pulcher ; x 2 '5. 
15. A vertical section through the outer part of Pachastrella^ ahyssi, a, showing species of 
Poecillastra,^ c, incrusting the outer surface ; x 5. 
Figs. 16-20. SpMnctrella crihrifera, . . . .87 
JJ 
5J 
16. The oscule, showing the floor of the cloaca; somewhat magnified, about 4 diameters. 
17-20. Spicules — 
Fig. 17. Oxea; x 34. 
,, 18. Orthotrisene; x 34. 
,, 19. An abnormal form of orthotrisene, with 
an adventitious fourth clsidus; x 34. 
Fig. 20. Metaster and spiraster; the upper of 
the two figures is the metaster ; 
X 300. 
21-29. Spicules — 
Figs. 21-29. Calthropella simplex. 
Fig. 21. Calthrops reduced to a diactinate form; 
X 34. 
„ 22. Triod; x 34. 
,, 23. Calthrops; x 34. 
„ 24. Triod, with the third actine reduced to a 
spine; x 34. 
,, 25. Calthrops reduced to a diactinate form, ' 
but with one of the actines traversed 
by two axial rods, while traces of a 
fourth are seen at the origin of the 
axial rods; x 34. 
Fig. 26. Calthrops, with several (three) adven- 
titious actines; x 34. 
,, 27. 'Triod with one actine grown out into 
stunted cladi, and so presenting a 
resemblance to the epactine of a 
Lithistid desma; x 34. 
,, 28. Spheraster, fully grown; x 225. 
,, 29. Young form of spheraster; x 225. 
107 
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30. Spicules — 
Fig. 30. Astropeplus pulcher , . 
a, Microtriod; b, Microcalthrops; 'c, d, e, Pentactinate forms of aster; /, g, Smaller asters; x 360. 
422 
Both these generic names have been changed since the Plate was printed off. 
