ZOOPHYTES. 331 



hours. Hold it between your eye and the light; do you 

 not see that the water is alive with tiny dancing atoms 1 

 Hundreds are there, playing and pumping through the 

 fluid with a sort of napping 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 knob 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 

 energetic 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, 

 sometimes 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 per- 

 petually 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 



