THE REGENERATION OF GONIONEMA. 7 



manubrium developed as shown in Fig. 7, c. All stages were 

 found, from those in which each manubrium was distinct and had 

 a separate pouch, through those in which two manubria were 

 attached to a single pouch, and finally to those in which a single 

 manubrium was branched or bifurcated at its distal end. 



The fact that such a considerable per cent, developed double 

 manubria assumes new interest when it is noted that this is not 

 simply the result of artificial mutilation and regeneration. Several 

 specimens of Gonionema have been taken from the eel pond 

 near the laboratory, in which double or bifurcated manubria were 

 present. Furthermore, this is not limited to Gonionema. Dur- 

 ing the summer of 1902 a specimen of Oceania languida was 

 taken by C. W. Hargitt, in the "tow" in Vineyard Sound, in 

 which two manubria were present. In this specimen three ra- 

 dial canals met normally in the center of the subumbrella. The 

 fourth canal was not complete, extending from the marginal canal 

 only about half way to the center. At the union of the three 

 canals a large four-lobed manubrium was present. At the inner 

 end of the fourth short canal was a small manubrium. This 

 small manubrium was only three-lobed and had three oral frills, 

 and in this resembled some of the regenerated manubria in 

 Gonionema \\\\\ch had only two or three lobes. This small manu- 

 brium in Oceania may perhaps be interpreted as a case of adaptive 

 regeneration. The short canal not having any direct connection 

 with the center of the chymiferous system may have been nearly, 

 if not entirely, deprived of the circulation of the chymiferous 

 fluid, and thus threatened with atrophy ; and the new manubrium 

 may have been formed to remedy this condition. This would be 

 more important inasmuch as the gonad on this canal was as per- 

 fectly developed as those on the other canals. In both the cases 

 just mentioned both of the manubria were active and functional. 



In the second set the wound entirely healed as noted above, 

 and then in two specimens the bell evaginated. The next day 

 the evaginated ones died without having developed manubria or 

 gastric pouches. In one specimen, Fig. 8, the canals did not 

 unite as in former cases but in the form of a ring, and two manu- 

 bria formed on opposite sides of the ring. They did not form at 



