PLATE XVI. 
PAGE 
Figs. 1-5. Astrella vosmaeri, . . . . .136 
Figure 1. Sponge, seated on a specimen of Stelletta plirissens •, nat size. 
„ 2-5. Spicules — 
Fig. 2. Dicliotri»ne ; x 32. Fig. 5. Abnormal termination of an oxea, resem- 
,, 3. Cladal end of anatrisene ; x 95. bling an anamonane ; x 32. 
„ 4. Pycnaster; x 540. 
Figs. 6-20. stelletta phrissens, . . . .150 
6, 7. Two examples of tlie sponge •, nat. size, 
8-11. Spicules — 
Fig. 8. Dicbotrisene ; x 32. i Fig. 10. Oxyaster ; x 540. 
,, 9. Cladal end of anatrisene ; x 292. | ,, 11. Spberaster; x 540. 
12. Eadial section through the cortex ; x 49. 
13. Transverse section through the inner fibrous layer of the cortex; x 292. 
14. Transverse section through an excurrent canal and adjacent sarcencbyma ; x 180. 
15. Transverse section through the ectosome and adjacent choanosome of the very young 
, sponge ; X 360. 
16. A similar section taken from a stUl younger sponge than the preceding; x 360. 
17. Vertical median section through a young sponge, more advanced than the preceding; x 49. 
(This is worked out in greater detail in the woodcut on page xxiii.) 
18. Section through the choanosome of the youngest example met with, showing that the aphodal 
character of the chamber system is established at a very early stage; x 292. 
19. Transverse section through the sponge at a later stage than that of fig. 17; x 10. 
20. Transverse section through the cortex of fig. 19; x 125. 
