ON THE DEVEr.OPMENT OF TUBULTPORA. 123 



phores, where specially important processes of growth are 

 taking place. 



It would be interesting to know the fate of the vesicles when 

 a brown body is formed. I have not as yet obtained any 

 satisfactory evidence on this point, the colonies found in the 

 spring having been almost completely devoid of brown bodies. 

 It is not improbable that the vesicles found in the tentacles, at 

 least, are in some way got rid of when a brown body is formed. 



V. Description of the Development. 



The ovicell of Tubulipora is in its development, in certain 

 respects, intermediate between that of Crisia and that of 

 Lichenopora, a conclusion which might be expected from a 

 consideration of the adult characters of the three genera. 

 The account given in my preliminary note (17) of " Id m one a 

 serpens " really refers mainly to what is here termed Tubu- 

 lipora pluraosa, though I now find that the sections on 

 which that account was based were partly prepared from T. 

 phalangea. 



The following account refers indifferently to T. plumosa 

 and T. phalangea if no species is mentioned. Where state- 

 ments are made with regard to T. phalangea, it must be 

 understood that the evidence for the specific determination 

 was, unless the contrary is stated, the absence of excretory 

 vesicles in the tentacles. This negative evidence is not so 

 satisfactory as the positive evidence, afforded by their presence, 

 that a given specimen belongs to T. plumosa; since it is 

 possible to overlook in the sections vesicles which are not very 

 numerous. It may be noted that the material used for the 

 study of the development of these two species was derived 

 almost entirely from a single haul of the dredge which brought 

 up Rhodymenia ciliata, on which T. plumosa and T. 

 phalangea alone were discovered. 



The specimens of T. liliacea were from Hydroids in deeper 

 water at Plymouth, and the species was determined before 

 they were decalcified. 



