284 BOTANICAL GAZETTE [APRIL 
has not been seen. One large plant deviated still more, showing mostly 
three glands, and the white margins of the leaves very narrow. I wrote 
to Professor AVEN NELSON about this, and he replies ‘‘all Colorado speci- 
mens do not show the reduction in number which you mention, and some 
of the specimens are quite devoid of white on the margins of many of the 
leaves.”” We seem to have a clear case in which a new race has been 
formed by mutation, or more precisely the meristic variation of BATESON. 
Incidentally it seems fairly evident that the genus Dichrophyllum cannot 
be maintained; so we have: 
Tithymalus marginatus (Euphorbia marginata Pursh, 1814); 
T. marginatus tetramerus, var. nov., the Boulder race with four glands.— 
T. D. A. CocKErRELL, University of Colorado, Boulder. 
