ZOOPHYTES. 331 



hours. Hold it between your eye and the light ; do you not 

 see that the water is alive with tiny dancing atoms ? Hun- 

 dreds are there, playing and pumping through the fluid 

 with a sort of flapping motion, which, when you get one 

 sidewise in clear view, will not fail to remind you of 

 the flagging flight of some heavy-bodied, long-winged 

 bird. These are the Medusa-shaped progeny of the 

 Laomedea. 



But let us return to the one of which we have just wit- 

 nessed the birth, and which is still flapping to and fro in 

 the narrow glass trough. You see a pellucid colourless 

 disk or umbrella of considerable thickness, about one- 

 sixtieth of an inch in diameter in its average state of 

 expansion. Its substance has a reticular appearance, pro- 

 bably indicating its cellular texture. Internally, the disk 

 rises to a blunt point in the centre, whence four vessels 

 diverge to opposite points of the margin. These form 

 elevated ribs, the surface being gradually depressed from 

 each to the centre of the interspace. Externally, the 

 centre of the disk is produced into a fleshy peduncle, 

 having a narrow neck, and then expanding into a sort of 

 secondary disk, of a square form, with the angles rounded. 

 This organ, which is capable of varied, precise, and ener- 

 getic motions, corresponds to the peduncle of a true 

 Medusa, the angles being the lips. These lips, which 

 correspond in their direction to the four internal ridges, 

 are very protrusile ; and, when the little animal is active, are 

 continually being thrust out in various directions, some- 

 times everted, but more commonly made to approach each 

 other in different degrees ; sometimes one being bent-in 

 towards the centre, sometimes all closing-up around a 

 hollow interior. These four lobes, thus perpetually in 

 motion, and changing within certain limits their form and 

 their relation to each other, remind one of the lips or the 

 tongues of more highly organised animals. The substance 

 of this peduncle appears to be delicately granular; but 



