CHAP. XVI.] 



radial series : Aurelia. 



427 



Next, the number of certain organs may vary independently of 

 other organs. For example as seen in Fig. 128, VI the radial canal 



Fig. 128. Diagrams of various forms of Aurelia aurita, slightly simplified from 

 Eojianes. I. The normal. II. Symmetrical form with 6 radii. III. Two 

 additional chief radial canals in opposite interradii (where manubrial lobes also 

 were bifid) and substitution of two canals for one in another interradius. 

 IV. Form with two generative organs. V. Form with three generative organs. 

 VI. Symmetrical form in which the intergenital canals are all doubled, the others 

 remaining single. VII. Apparently upper half-disc arranged as for a symmetry of 

 four, lower half for a symmetry of six. VIII. One of the quadrants tripled (?). 

 IX. Form resembling VI. except that in one quadrant the intergenital canal is not 

 doubled. The descriptions are not altogether those of Romanes. 



normally lying in a plane between each pair of generative organs may 

 in each quadrant be represented by two canals, and in correspondence 

 with this change the number of marginal organs is proportionately 

 changed in the quadrants affected. 



But besides these changes symmetrically carried out in eacli quadrant 

 or in the whole disc, one or more quadrants or a half-disc may vary inde- 

 pendently. For example Fig. 128, VII, shews a specimen in which the 

 two upper quadrants are normal but the lower half-disc is primarily 

 divided into three. (In the case figured the parts of the lower half-disc 



