$76 EVENINGS AT THE MICROSCOPE 



each pair being approximate, and appropriated to each of 

 the quadratures of the circle. Each of these organs con- 

 sists of a transparent globe, not enveloped in the substance 

 of the disk, but so free as to appear barely in contact with 

 it: it contains a single otolith, of high refractive power, 

 placed not in the centre, but toward the outer side. The 

 inexperienced naturalist, on first seeing these organs, would 

 unhesitatingly pronounce them eyes, and the otolith the 

 crystalline lens. They are, however, pretty certainly, ru- 

 dimentary organs of hearing; the crystalline globule or 

 otolith being capable of vibration within its vesicle. Their 

 exact counterparts are found in many of the smaller Me- 

 dusas, as we lately saw in the Thaumantias. 



The disk is endowed with an energetic power of con- 

 traction, by which the margin is diminished, exactly like 

 that of a Medusa swimming; and the tentacles have also 

 the power of individual motion, though in general this is 

 languid, their rapid flapping being the effect of the con- 

 traction and expansion of the disk, producing a quick in- 

 volution and evolution of the margin, and carrying the 

 tentacles with it. Occasionally, however, all the tentacles 

 are strongly brought together at their tips, with a twitch- 

 ing grasping action, like that of fingers, which is certainly 

 independent of the disk, and may be connected with the 

 capture of the prey, 



Now every detail of the structure here, as well as the 

 general form, appearance, and habits, agrees with the small 

 naked-eyed Medusas, so closely that if we had not wit- 

 nessed the birth of the little creature from the reproduc- 

 tive cell of a Laomedea, we should have pronounced it 

 with unhesitating confidence a true Acaleph. The pe- 

 duncle, it is true, seems out of place, being on the out- 



