98 SIDNEY F. HARMER. 



been made to me by Mr. A. H. Church, whom I had consulted 

 on the growth of Tubulipora. Mr. Church informs me that 

 Rhodymenia ciliata, a red seaweed on which I obtained 

 nearly all the material (T. phalange a and T. plumosa) 

 which I have used for sections, is an annual. It follows, 

 therefore, that even the largest colonies (some 12 — 15 mm.) 

 found on this seaweed must represent the growth of one year. 

 Mr. Church informs me that R. ciliata usually dies in the 

 winter, the middle of which period may be regarded (for Algse) 

 as February, but that the specimens I dredged (in a sheltered 

 estuary) at the beginning of April must have grown in the 

 preceding year. I have not noticed processes of regeneration 

 in colonies growing on seaweeds, the evidence from which is 

 not entirely concordant with that from shells. The specimens 

 growing on Rhodymenia (and the same is true of specimens 

 of T. plumosa collected at the same season on Saccorhiza 

 bulbosa) show no apparent discontinuity of growth, nor were 

 any stunted mature colonies observed in this situation. The 

 colonies were probably far too large to have grown in the year 

 in which they were collected ; and although the growth may 

 have been less active or dormant during the winter, there was 

 no interruption sufficient to give rise to a marked discon- 

 tinuity, as in the specimens growing on shells. It may, how- 

 ever, be noticed that there is no reason for assuming that 

 these latter were the growth of the year immediately preced- 

 ing. They may be evidence of unfavorable conditions more 

 than one year before, in which case the absence of similar 

 colonies on the Rhodymenia growing in the same locality 

 would be due to the fact that this plant is an annual. I 

 think it follows from the observed facts that growth may 

 start at any time when the species is breeding, and that a 

 colony which begins existence in the summer continues 

 to live through the winter, and produces ovicells in the 

 spring. 



Mr. Church informs me that in some cases of regeneration 

 which he has observed (on a glass bottle) the central part of 

 the colony had decayed, leaving the new growths with a vacant 



