86 ZOOPHYTES. 



This product is always seen as a parasite. In earlier stages it rather 

 assumes a fan shape, expanding into those divisions compared to ramifica- 

 tions, when more mature. But the form of the growth may be modified 

 by position. When established on the slender parts of the Sertularise, it 

 appears to most advantage, the subordinate organization then projecting 

 free and uninterrupted. In the course of increment elsewhere, however, 

 it often becomes so confused, as to produce more resemblance to an irre- 

 gular investing scurf, which precludes comparison to any definite figure. 



The tube is occupied by an ascidian hydra with twelve tentacula. 

 as enumerated in two individuals. But some have certainly more. — 

 Fig. 15, a. 



Very minute corpuscula whose origin could not be ascertained, ap- 

 peared in a vessel containing specimens of the Tubipora. 



The whole substance of the polyparium is hard and shelly. 



Plate XVIII. Fig. 11. Tubipora serpens. 



1 2. The same, enlarged. 



13. Another specimen. 



14. The same, enlarged. 



15. Another specimen, natural .size. 

 15. Hydree in their tubes, enlarged. 



