Evans, who, with Mr. Nealley, continued work westward, during
July and a part of August, to southern California, along the
Southern Pacific Railway. As a result a large number of complete
plant bodies was secured, but very few of them were in flower and
the field notes indicated little besides collection stations.
During the following fall and winter preliminary determinations
of this material were made by Mr. Evans.
In the fall of 1892 critical study of this and other collections
was begun in connection with my assistants, Dr. Elmon M. Fisher
and Mr. Edwin B. Uline, who have ever since rendered constant and
most import assistance in the examination of material and
bibliography, which alone has made the work possible in the midst
of other pressing duties.

In the spring of 1893 these two gentlemen spent several weeks at
the Missouri Botanical Garden in the critical study of its rich
material, and during the latter part of their stay I assisted in
the work. Dr. William Trelease, the director of the garden, had
hastened the arrangement of the Engelmann material, and had
mounted in convenient form the large mass of notes left by Dr.
Engelmann. These notes contained not only critical remarks upon
known species, but also the diagnoses of many unpublished species
which had come into his hands, notably those collected by Mr.
William Gabb in 1867 in Lower California. The collections that
have thus far been studied are:

(1) Those of the Missouri Botanical Garden; and thanks are
especially due to Dr. Trelease for his generous cooperation in
the use of this material, without which the work would have been
impossible.