The Journal of experimental zoology . e interradial canal, and thecontiguity of two adradials. Fig. 12. Diagram of medusa showing adradial rhopalium at a and lack of perradials in the octo-meres drawn. Very small degenerate gonad in upper left hand pouch. Fig. 13. Branched adradial canal at a, and at x the complete blending of the several canals of thesegment into one system. 572 Chas. W. Hargitt. six gonads, six oral arms, and eleven rhopalia, the twelfth beingabsent and its perradial canal system likewise lacking, as shownat P, and still the general symmetry is hardly affected. On the other
The Journal of experimental zoology . e interradial canal, and thecontiguity of two adradials. Fig. 12. Diagram of medusa showing adradial rhopalium at a and lack of perradials in the octo-meres drawn. Very small degenerate gonad in upper left hand pouch. Fig. 13. Branched adradial canal at a, and at x the complete blending of the several canals of thesegment into one system. 572 Chas. W. Hargitt. six gonads, six oral arms, and eleven rhopalia, the twelfth beingabsent and its perradial canal system likewise lacking, as shownat P, and still the general symmetry is hardly affected. On the other hand, in several of the photographs, particularlyFigs. 4 and 5, it will be seen at a glance that the symmetry ismore or less seriously disturbed. In still others, while the generalsymmetry might not appear to be seriously affected, when atten-tion is directed to the marginal symmetry it will be seen to havesuffered 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 fromFig. 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 thatsingle segment, the other seven remaining normal. And thus it is throughout; variations in one organ involvingin many cases more or less distortion of the correlated organs, oreven the entire organism. In other cases the variation has beenassociated with a regulative adjustment which has more or lessserved to maintain a fairly definite symmetry of both the immediateorgans and the entire animal symmetry. In connection with the study of ephyrae already given, attentionwas directed to the occurrence of twin rhopalia in several instancessome of which are illustrated in several of the figures. Suchdouble structures have been observe
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