2IO 



H. P. KJERSCHOW-AGERSBORG. 



elsewhere ('18). The radial symmetry is, indeed, superimposed. 

 Cole ('13) demonstrated with marked clearness, experimentally, 

 what Cuenot and Delage and Herouard had demonstrated mor- 

 phologically, viz., that ray III. is the anterior ray. Cole, from his 

 experiments on Asterias forbesi, constructs a line of bilateral sym- 

 metry with regard to his records ; an approximately equal number 

 of trials fall on each side (Fig. 8). A line drawn perpendicular 



FIG. 7. Diagram of an adult individual of the twenty-rayed starfish to 

 show the bilateral appearance in an individual actively moving about, and the 

 relation of the madreporite ('"p,) to the physiological anterior end (rays I V) ; 

 and of the anus (a) to the rest of the dorsal disk. A, primary posterior ray. 

 rx-rx^, the oldest and youngest right post-larval rays ; lx-l.v 6 , oldest and 

 youngest left, post-larval rays. 



to the line of bilateral symmetry, intersecting mid-dorsally, brings 

 out of the total number of 499 trials : 347 ahead of it, e.g., on the 

 side which bears the madreporic plate; 152 behind, or to the side 



