270 BULLETIN: MUSEUJI OF COMPARATIVE ZOOLOGY. 



Should these types prove not to be of the value of varieties, they may 

 still possibly be correlated with the methods of reproduction. Besides 

 the sexual method, Metridium marginatum reproduces non-sexually by 

 small buds cut off from the mai'gin of the animal between its aboral 

 disk and its column. This method of reproduction, long ago hinted at 

 by Verrill ('69, p. 257), can usually be seen taking place in any large 

 specimen. Similar conditions have been observed in Metridium dianthus 

 by G. Y. and A. F. Dixon ('91, p. 20), and by Carlgren ('93, p. 108). 

 Possibly the two types here described are the products, one of the 

 sexual, the other of the non-sexual, method of reproduction. The solu- 

 tion of this question, however, must be left to future investigation. 



Cambridge, January 9, 1897. 



