104 ZOOPHYTES. 



portion was long, short, spherically triangular, or otherwise, so was the 

 marginal border, fig. 4. 



The whole subjects inspected were at the bottom of a watch-glass ; 

 and all were yet in motion. 



A gi-eat profusion of the brownish substance like dust had been dis- 

 charged by each of the four Medusae obtained on August 24. Next day, 

 August 25, six vessels, each containing a portion of it, were set aside. 



In forty-eight hours, namely on August 27, the appearance of spots 

 of scum at the surface of the water in some of the vessels, announced the 

 progress of certain alterations below. 



On applying these spots to the microscope, they were plainly dis- 

 covered to consist of the planulse in a state of advancing metamorphosis. 

 All remained still and floating. Some of the least altered approached a 

 shuttle-shape, with an orifice in the centre : the ends of the shuttle were 

 more prolonged in others, — several shewed obvious indications of four 

 incipient arms, in unequal progress, around the central orifice, fig. 5. 



On the following day, August 28, a remarkable change had ensued. 

 The metamorphosis was rapidly advancing ; for the elongating arms pro- 

 mised to be of peculiar tentacular texture, fig. 6, as amply realized in 

 three days longer. 



Now their extent equalled some diameters of the body ; — the two 

 from the ends of the shuttle remaining always more prolonged than the 

 others, figs. 7, 8. Both the subjects there represented as the most favour- 

 able for illustration, floated reversed when delineated, whereby the orifice 

 being below is not seen, and some of the tentacula, along with the upper 

 surface, are directed downwards. 



All this was an extraordinary exhibition in the offspring of such pa- 

 rents — that so lately issuing as mere and almost invisible dust from com- 

 pact, massy, ponderous animals, alike singular in habits, in form, and in 

 substance. 



But Nature had an important purpose to fulfil : the apparently rude 

 commencement had to be carried through, by wonderful expedients, to 

 symmetrical perfection in the end. In eleven or twelve days after the 



