PLATE XIII. 



EUDENDRIUM RAMOSUM. 

 Figs. 



1. A portion of a male colony cut from the end of a primary branch, magnified. Some of the 



hydranths are seen to be loaded with bithalamic gonopliores, while they still retain their 

 tentacles ; in others, the tentacles have disappeared, and the hydranth has become con- 

 verted into a pseudo-blastostyle. 



2. A colony of tlie natm'al size attached to the back of an oyster-shell. 



3. A hydranth, with part of its supporting ramulus, from a female colony. The gonophores 



are seen springing, some from the body of the hydranth, and some from the distal part 

 of the ramulus. In some of the younger gonophores the spadix is seen bending round 

 the ovum, so as to embrace it in its curvature; in the more mature ones the ovum has 

 undergone segmentation and fills the cavity of the sporosac. 



4. Male sporosac more magnified than in fig. 1. 

 5 — 16. Development of the embryo. 



5. Very young female sporosac containing a single ovum, in which the germinal vesicle and 



germinal spot are still visible ; the spadix is seen to be pushed to one side by the ovum, 



and to be gradually curving round it. 

 0. Same more advanced ; the spadix has now almost entirely surrounded the ovum. 

 7. A still older sporosac, in which the fecundated ovum has attained an advanced stage of 



segmentation. 

 S. Isolated segment-spheres more magnified. 

 9. Germinal vesicle from an earlier stage of the ovum, isolated, and showing the germinal spot 



and its contained punctum. 



10. The ciliated planula. 



11. The planula after it has lost its cilia, previously to becoming fi.xed. 



12. The plamda become fixed by a disc-like enlargement of one extremity. 



13. Embryo more advanced; the disc of fixation more decidedly differentiated, while a delicate 



chitinous perisarc has become excreted over the whole surface of the embryo. 



14. The disc has begun to l)e divided into radiating lobes, and the hypostome has become 



differentiated. 



15. The hydranth is now distinctly differentiated from the hydrocaulus, while the tentacles have 



begun to sprout round the hypostome, and within a delicate chitinous sac, which enve- 

 lopes the whole. 



16. The hydranth has attained to nearly its ultimate form, and has burst through the chitinous 



sac, which had hitherto confined it, and the tentacles are now free to extend themselves 

 in the surrounding water. 



17. Spermatozoa. A minute corpuscle, like a parietal nucleus, is seen adherent to the head 



of each. 



