572 



Chas. W. Hargitt. 



six gonads, six oral arms, and eleven rhopalia, the twelfth being 

 absent and its perradial canal system likewise lacking, as shown 

 at P, and still the general symmetry is hardly affected. 



On the other hand, in several of the photographs, particularly 

 Figs. 4 and 5, it will be seen at a glance that the symmetry is 

 more or less seriously disturbed. In still others, while the general 

 symmetry might not appear to be seriously affected, when atten- 

 tion is directed to the marginal symmetry it will be seen to have 

 suffered quite definitely, in one case three rhopalia instead of one, 

 occupying a single octant. In such a case, which is not rare 



Fig. 14. Diagram showing a branched adradial canal and rhopalium shown at a sketched from 

 Fig. 2 of plate. 



Fig. 15. Diagram of the specimen shown in Plate I, Fig. 4, adradial canal and organ at a, 

 perradial system at p, interradial absent or fused with the former. 



the variation would seem to have been restricted wholly to that 

 single segment, the other seven remaining normal. 



And thus it is throughout; variations in one organ involving 

 in many cases more or less distortion of the correlated organs, or 

 even the entire organism. In other cases the variation has been 

 associated with a regulative adjustment which has more or less 

 served to maintain a fairly definite symmetry of both the immediate 

 organs and the entire animal symmetry. 



In connection with the study of ephyrae already given, attention 

 was directed to the occurrence of twin rhopalia in several instances 

 some of which are illustrated in several of the figures. Such 

 double structures have been observed in adults, though unless 



