158 Royal Society : — • 



tentacles. The figures are evidently very erroneous. The cor- 

 responding description I have been unable to refer to, the volume 

 containing it being wanting in the Hawaiian Government copy. 



In the Zoology of the ' Voyage de TUranie,' Quoy and Gaimard, 

 Paris, 1824, p. 65(3, is a description of the polyps of Heliojiora 

 (^Pocillopora) ccerulea. 



The expanded polyps have radiated tentacles, and are said to 

 entirely hide the corallum when they are in an expanded condition. 

 Experiments proved that communication between the animals is 

 somewhat imperfect, since a stimulus applied to any part of the 

 colony caused only the polyps in that immediate neighbourhood to 

 retract themselves. 



In the plates of the ' A^oyage de FUranie,' pi. 96. figs. 5, 6, 7, 

 Heliojjoni is figured, showdug in fig. 5 the appearance of the coral in 

 the fresh state, but wilhout any representation of the polyps. 



December 9, 1875. — Dr. J. Dalton Hooker, C.B., President, in the 



Chair. 



" On the Development of Lepas fascicularis and the 'Archizoea^ 

 of Cirripedia." By E. von Willemoes-Suhm, Ph.D., NaturaHst 

 to the ' Challenger ' Expedition. 



The materials for this paper were obtained during the ' Chal- 

 lenger's ' cruise from Japan to the Sandwich Islands in 35° lat. 

 N., when very curious Ncmplii, some of them 12 millims. long, 

 were caught, which were identified at once as belonging to the 

 nauplian form to which Dohrn has given the generic name of 

 '■'■Archizoea.^' In the daytime these lan'se were scarcer, but at 

 night so common that large bottles could be filled with them. 

 The question (which had been left open by Dohrn) to which cirri- 

 ped these extraordinary Naujilii might belong -was solved when 

 large quantities of Lepas fascicularis were seen passing the ship for 

 more than a week. It was then possible to keep these barnacles 

 alive and to bring up in our globes such stages of the large 

 Nauplii as had also been taken on the surface. Then, again, when 

 catching the surface-animals, free-swimming pu^^a? were found, 

 which were seen to settle on dead Velelke and assume the form 

 of Lepas fascicularis, so that the whole development of this species 

 could be worked out. 



Reasons are given why this barnacle belongs to the species 

 Lepas fascicularis ; and a description is given of some parts of the 

 mouth, which slightly differ from those described by Darwin in the 

 same species. 



I, Development of the egg and of the yowigest Nauplius. 



The conclusions to which an investigation into the development 

 of the ovum, and into the changes which occur in it after its 

 formation up to the time when the Nauplius comes out, has led are 

 the following : — 



