PREFACE. 
Vll 
From the time of the Commission’s landing at 
Indianola, during the whole period of its continuance, 
every opportunity that oJBfered, without interfering 
with the direct object had in charge, was improved 
for the purpose of making explorations, and forming 
collections in various departments of natural science. 
In the department of Botany four gentlemen were 
employed in making collections. Dr. J. M. Bigelow, 
Surgeon of the Commission, and Mr. George Thurber, 
who was most of the time connected with the Quarter- 
master and Commissary Departments, in addition to 
their other duties, examined the botany of the region 
respectively passed over by them, and made very large 
collections of plants — the latter over a country extend- 
ing from the Gulf of Mexico across the continent to 
the Pacific Ocean. Mr. Thurber, who accompanied 
me in most of my journeys, was indefatigable in his 
exertions to make thorough examinations and complete 
collections of every thing belonging to his department, 
notwithstanding the numerous obstacles he had to 
encounter. He, in addition, formed an extensive 
herbarium, embracing plants, etc., collected in the 
various States of the republic of Mexico visited by us. 
Two other botanists. Dr. C. C. Parry and Mr. Charles 
Wright, have also made large collections. The former 
was connected with the surveying parties under the 
immediate direction of Major Emory, and did not 
accompany me, so that I am unable to speak from per- 
