FISSION IN ACTINIA BERMUDENSIS VERRILL 49 



member of a fourth pair, of non-directives. The fundaments 

 of the other member of the fourth and of both members of the 

 fifth pair of complete mesenteries had formed, as well as those of 

 two pairs of incomplete mesenteries. The fundaments of the 

 three complete and four incomplete mesenteries arose from the 

 new tissue that had regenerated at the region of the final rup- 

 ture of the two daughter animals. This regenerated portion of 

 the wall was quite convoluted and irregular in outhne. 



The other individual (fig. 5, y) resulting from the sphtting of 

 Actinia A was very similar in structure to x. The right half of 

 this animal, being derived directly from that of the original 

 individual, was entirely normal in structure. The missing half 

 of each pair of directives had been formed, as well as two pairs 

 of non-directives. One mesentery of each of two other pairs of 

 non-directives was complete and their mates were partially so. 

 A single fundament of another non-directive had appeared on 

 the regenerated tissue of the ruptured portion; but no trace of 

 its mate, nor of any of the incomplete mesenteries, could be 

 recognized. As before, the regenerated tissue was irregular in 

 outline and thicker than the neighboring portions of the column 

 wall. 



The other double actinian, B, (fig. 2) did not have the mouth 

 entirely separated into two when found, as had actinia A , neither 

 did it entirely divide into two individuals during the four weeks 



Fig. 2 Drawing of Actinia B, oral view, showing tri-glyphic mouth. 



Fig. 3 Diagram of mesenteries as seen through oral disc of A at time of first 

 observation. 



Fig. 4 Diagram of mesenteries as seen through oral disc of A just before 

 the final step in the longitudinal fission occurred. 



Fig. 5 Section through the two daughter animals resulting from the division 

 of A, showing relative positions of the mesenteries. 



Fig. 6 Diagram of mesenteries as seen through oral disc of B at time of first 

 observation. 



Fig. 7 Section through B just .below the oral disc, showing the relative posi- 

 tions of the mesenteries four weeks after figure 6 was made. Upper ends of 

 two esophageal tubes entirely separate. 



Fig. 8 Section through B at lower end of esophageal tubes, showing common 

 opening of mouths into gastro-vascular cavity. A double set of siphonoglyphs, 

 however, is present. 



JOURNAL OF MORPHOLOGY, VOL. 31, NO. 1 



