INTRODUCTION. XXIX 



existence, and which disguised its real affinities, is cast 

 aside, and that which remains is at once recognized as a 

 polypite. During the period of quiescence the ova are 

 liberated, and the mamibrmm then dissolves away *. 



It would be difficult to exaggerate in speaking of the 

 beauty of these floating flower- buds, as they may well be 

 called. The vivid tints which they often display, the 

 gracefulness of their form, the exquisite delicacy of their 

 tissues, and the vivacity of their movements, combine to 

 render them singularly attractive. Frequently they are 

 so perfectly translucent that their bubble-like forms only 

 become visible in a strong light. In other cases the um- 

 brella is delicately tinted, while the manubrium displays 

 the gayest colouring, and brilliant ocelli glitter on the 

 bulbous bases of the tentacles. To their other charms that 

 of phosphorescence is often added; they are not only 

 painted like the flower, but at night they are jewelled with 

 vivid points of light, set round the margin of the bell, or 

 one central lamp illumines the little crystal globe, and 

 marks out its course through the water. Though indi- 

 vidually minute, their numbers are so immense that they 

 play an important part in the production of the luminosity 

 of the ocean. The surface of the sea for miles together 

 is often thickly covered with them ; and on still, sunny days 



* This " retrograde metamorphosis " has been observed by Dujardin and 

 Holdsworth in Cladoncma in Podocoryne by Loven, Peach, and myself, in 

 Byncoryne by Allman and myself, and in Turris by Gosse, who remarks, 

 after describing the reversion and disappearance of the umbrella, "of the 

 scores kept, this was the common, and therefore, I suppose, the natural ter- 

 mination." I have observed the same thing universally in Podocoryne carnea. 

 The gonozooid of Clavatella, which has no swimming-bell to dispose of, 

 equally loses its locomotive habit towards the close of its life, and fixing itself 

 by the suctorial disks that had before served it as feet, remains perfectly 

 inactive until the escape of the ova, which is speedily followed by its own 

 dissolution. 



