with descriptions of some new species. 357 



matter which pervades the creeping fibre. The polypes are very 

 shy and wary, and will remain for a long time without issuing 

 from their cells. 



ElJCRATEA CHELATA. 



The polype of this species, which is closely related in struc- 

 ture to Anguinaria, is of extreme delicacy and beauty, and re- 

 markable for the vivacity of its movements. In a moment it 

 retracts itself, and the moment after darts from its little cell, 

 bending its arms backward and forward with inconceivable quick- 

 ness. The number of the tentacles is twelve. 



Cellepora pumicosa. 



The polypes are of a delicate orange colour, and singularly 

 graceful in their form and movements. They are large, and pro- 

 trude much beyond the cell when extended. The viscera are 

 marked by dark spots. 



Lepralia pediostoma. 



Tentacles sixteen, long and slender. The aperture of the cell 

 is covered by a horn-coloured operculum, which, when the polype 

 extends itself, slides back, as it were, within the cell. 



Flustra hispida. 



The development of the ciliated gemmules has been described 

 by Sir John Dalyell and others. I venture to add a few notes 

 to their interesting observations. From a specimen procured in 

 the month of May a large number of gemmules were excluded. 

 They were found clustering about the surface of the fleshy mass. 

 I was not fortunate enough to see any of them actually excluded, 

 but there can be little doubt that they escape through the skin. 

 The gemmule is a very beautiful object. It is of a semioval 

 form, white, and thickly fringed with cilia round the border. It 

 consists of a transparent case, inclosing an opake nucleus. The 

 margin is broken into lobes, which bear a multitude of long and 

 somewhat coarse cilia. At each extremity there is a tuft of very 

 delicate hairs, which I have noticed in motion some time after 

 the rest of the cilia have ceased to play. At the top of the back, 

 between the nucleus and the outer case, is a small projection 

 (PL XIV. fig. 1 a), or handle, which seems to disappear when 

 the gemmule attaches itself. Towards one end of the nucleus I 

 have repeatedly observed a curious movement quite independent 

 of the cilia, such as might be produced by a number of setce sweep- 

 ing backward and forward. At the same point there was an 

 appearance of structure, but I have not been able to arrive at 

 any certain conclusions about it, and may very possibly have 



