270 BULLETIN: MUSEUM OF COMPARATIVE ZOÖLOGY. 
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 margin 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. 
