OFFSPRING OF MEDUSA CHRYSAORA. 79 



be white, opake, and fleshy, tending to an elliptical 

 form, though very mutable one extremity generally 

 broader than the other, with which each individual 

 made its way amongst the multitude of its fellows. 

 All were crawling about the bottom of the glass with 

 a quick, smooth, lively motion. The body seemed 

 consistent and soft, evidently yielding to pressure, as 

 it forced its way through the crowd. No cilia or 

 other external organs could be detected, for perhaps 

 the magnifying powers were insufficient^. On the 

 whole, the animals evidently closely resembled the 

 Planula, hereafter to be described as the offspring of 

 many races of Polyps, such as the reader will find re- 

 presented in PL II. fig. 1, e. 



After the lapse of other forty hours these little 

 creatures began to appear of twofold composition, now 

 consisting of a lighter margin surrounding a darker 

 interior portion of corresponding form (PI. I. fig. 4, b) 

 previously the whole had a uniform homogeneous 

 aspect. Their shape had also become considerably 

 modified; but whatever the outline of the exterior, 

 that of the interior exactly corresponded. 



In forty-eight hours, namely on August the 27th, 

 the appearance of spots of scum at the surface of the 

 water announced the progress of certain alterations 

 below. 



On applying the microscope, these spots were plainly 

 discovered to consist of the Planufa in a state of ad- 

 vancing metamorphosis. All remained still and 

 floating. Some of the least-altered approached a 



* The cilia, with the aid of a good microscope, are distinctly 

 visible. 



