PLATE XLIV. 
Figs. 1-6. Tethya seycliellensis, . . . . 
Figure 1 . The sponge ; nat. size. 
„ 2. Portion of the external surface, somewhat enlarged, to show the character of the conules. 
„ 3. Also a part of the exterior surface, but taken from near the oscule, to show the modification 
which the conules undergo in this region. 
„ 4. Transverse section through the sponge ; the dark dots in the choanosome, are the ova, which 
occur scattered throughout it ; x 6-|-. 
„ 5. Section through part of the choanosome, showing the distribution of the ova ; x 32. 
„ 6. Section through part of the choanosome, showing the appearance presented by the flagellated 
chambers, and the minute characters of the ova ; x 292. 
Figs. 7-14. Tetliya japoniea, . . . . 
,, 7, 8. Two specimens of the sponge ; nat. size. 
„ 9. Part of the external surface, slightly magnified, to show the characters of the conules and the 
ridges by which the conules are united together ; x 6|. 
„ 10. Part of the external surface of the sponge represented by fig. 8 ; somewhat enlarged. 
„ 11. Transverse section, showing the conules of fig. 7 in longitudinal section ; x 6^-. 
„ 1 2. A median longitudinal section through one of the swellings at the end of the conules in fig. 7, 
supposed to be an external bud ; x 24. 
,, 13. A similar “bud” from Tetliya seycliellensis, showing the arrangement of the chief spicules; 
X 24. 
„ 14. A part of the section of fig. 12, more highly magnified, to show the composition of its 
tissues, which agree with those of the cortex ; x 292. 
Figs. 15, 16. Tethya ingalH, ..... 
„ 15. The sponge ; nat. size. 
„ 16. Transverse section through the cortex, and adjacent choanosome ; x 6-|. 
Figs. 17-19. Tetliya lyneuriimi, .... 
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17. An oxea split at the one end under the action of a cold solution of caustic potash ; x 292. 
18. An oxea showing the axial rod passing into the protoplasm of the scleroblast ; x 360. 
19. Two spherasters, as seen in the cortex, each embedded in a scleroblast; x 292. 
