SERTULARIA. 157 



Plate XXIII. Sertularia abietina. 



Plate XXIV. Sertularia abietina. 



Fig. 1. General arrangement of the parts. 



2. Cells and hydrse of an adult, enlarged. 



3. Compound vesicles, in situ. Spherules containing yellow corpus- 



culse, a ; vascular pedestal sustaining the spherules, h, enlarged. 



4. Planulse from the spherules, a, b, c ; enlarged, A, B, C. 



5. Nascent Sertularia, with the first cell advancing. 



6. Nascent Sertularia with two cells. 



7. The same, enlarged. 



8. Root of a nascent Sertularia, enlarged. 



9. Nascent Sertularia, with three cells. 



10. The same, enlarged. 



11. Nascent Sertularia with four cells. 



12. The same, enlarged. 



13. Nascent Sertularia. The rising spine shoots through the summit of 



the spherule of a compound vesicle, a, on its pedestal, J, enlarged. 



14. Another of similar description. 



15. Nascent Sertularia, with two hydrse, the stem having shot up from 



within the compound vesicle, a, enlarged. 



16. Another, farther advanced, enlarged. 



17. Another, still farther advanced, having three hydrse, enlarged. 



18. Arrangement of the cells, enlarged. 



19. Prolific simple vesicles, enlarged. 



Plate XXV. Figs. 1-5. Sertularia abietina — details. 



Fig. 1. Branch with ordinary ampullate or flask-shaped vesicles ; enlarged. 



2. Branch bearing compound vesicles. 



3. The same, enlarged. 



4. Planulse from these compound vesicles, enlarged. 



5. Planula metamorphosing ; now a spherical segment with a central 



spine, enlarged. 



§ Jj. Sertularia abietinula — Diminutive Sea-Fir. — Plate XXV. 

 figs. 6-13. — ^The narrow resemblance of this to the preceding species is 

 such, that it might be almost supposed the same in an early stage, or 

 a variety in miniature. But I have been unable to identify the two ; 



