ON THE LIFE-HISTORY OF PEDICELLINA. 147 



On the Life-History of Pedicellina. 



By 



Sidney F. Harmer, B.A., B.Sc, 



Fellow of King's College, Cambridge, and of University College, London. 



With Plates XVI and XVII. 



During the summer of 1885, spent in Rocquaine Bay, 

 Guernsey, I succeeded in obtaining material for the study of 

 the metamorphosis of Pedicellina echinata, a form which 

 occurs in great abundance (in Rocquaine Bay) on Coralline 

 growing under the shade of other seaweeds in tide-pools. 



The larvae of Pedicellina invariably refused to fix them- 

 selves when kept in a small quantity of water, and I therefore 

 ultimately adopted the following method for procuring the 

 various stages necessary for the investigation. 



Adult colonies were placed, after the removal of all super- 

 fluous parts of the Coralline on which they were growing, in a 

 small vessel, the mouth of which was closed by a piece of linen. 

 The vessel was then left for a day or more in a tide-pool, after 

 which a careful search (with the aid of a low power) over the 

 Coralline was generally rewarded by the discovery of several 

 young Pedicellina, which had resulted from larvae hatched in 

 the tide-pool, and which, owing to their inability to escape 

 from the vessel in which they were confined, had been obliged 

 to fix on the Coralline. After preservation with corrosive 

 sublimate and decalcification of the Alga, sections were easily 

 prepared. In this manner, I succeeded in obtaining numerous 

 individuals of various ages, fixed under perfectly normal con- 

 ditions. 



