PREFACE. 
The accompanying paper on the Allioniaceae, chiefly those of the 
United States, is by Mr. Paul C. Standley, assistant professor of 
botany in the Agricultural College of New Mexico. It was elab- 
orated under the direction of Prof. E. O. Wooton, of the same insti- 
tution. It embodies the results both of field work and of a study 
of herbarium material from most of the western herbaria, as well as 
the National Herbarium, and of all the literature of the subject. Mr. 
Standley has aimed at a comprehensive and thorough treatment of the 
whole group and has found it necessary to establish several new 
genera and restore others not recently accepted. The number of 
sheets studied belonging to the National Herbarium was 1,068. Of 
the 50 new species here described the types of 20 are in the National 
Herbarium, and others are represented here by duplicate types. The 
illustrations, except Plates XXXIV and XXXV, are from drawings 
made by Mr. Standley himself. 
Frepertck V. Covinue, 
Curator of the United States National Herbarium. 
It 
