210 
DOUGLAS HOUGHTON CAMPBELL 
however, in the position of the reproductive organs, the presence of a 
definite foot in the sporophyte, and in the presence of a distinct elatero- 
phore, as well as a different method of dehiscence. 
A comparison of the genera included in the families Aneuraceae 
and Blyttiaceae, viz., Metzgeria, Aneura, Umbraculum, Podomitrium, 
Calycularia, Morkia, Makinoa, Symphyogyna and Blyttia, shows that 
there are no constant features which can be used certainly to distinguish 
the two families from each other; it will probably be better, as Cavers 
has suggested, to combine the two families into a single one. 
