440 Butler : The western American birches 



slightly roughened bark, which is never shining and smooth as 

 in other birches. In size and shape, the leaves are much like 

 those of Betnia occidentalis but they are thick and dull and have 

 short teeth. The bark has sometimes the same bronze color but 

 is dull, never peels and is always mottled with gray. The twigs 

 are less resinous, dull, and roughened. The bractlets are also 

 quite different. It may possibly be a hybrid between Betula occi- 

 dentalis and some one of the thick-leaved species. It is appa- 

 rently not common, being known at present only in the type local- 

 ity. It is even more distinct in the field than in the herbarium, and 

 not likely to be confused with any other species. 



Columbia University, 

 New York City. 



