CACTACEiE OF THE UNITED STATES. 
The only Cactus known to Linnaeus from the countries north of 
Mexico was his Cactus Opuntia \{Opuntia vulgaris). Long after 
him, more than forty years ago, Nuttall, the pioneer of West Ameri¬ 
can botany, discovered two Mamillaries and two Opunticc on the 
Upper Missouri, and again, twenty years later, in California, a new 
Echinocactus. About ten years ago we became acquainted with nu¬ 
merous new Cactacese, in Texas through Mr. F. Lindheimer; in New 
Mexico through Dr. A. Wislizenus; and in Northern Mexico through 
the same explorer and Dr. J. Gregg: some others (and among them 
the giant of Cacti) were indicated in the Gila country by the then 
Lieutenant W. H. Emory. Soon afterwards Mr. A. Fendler col¬ 
lected several new species about Santa Fe. Mr. Charles Wright, 
a few years later (1849), discovered in Western Texas and Southern 
New Mexico still other undescribed Cacti. . 
But the greatest addition to our knowledge of the Cactacese of the 
southern part of the United States was made by the gentlemen con¬ 
nected with the United States and Mexican Boundary Commission, at 
first under Colonel Graham, and subsequently under Major Emory. 
Science is indebted principally to Dr. C. C. Parry, Mr. Charles Wright, 
Dr. J. M. Bigelow, Mr. George Thurber, and Mr. A. Schott, for val¬ 
uable collections of living as well as dried specimens, and for full 
notes taken on the spot. 
About the same time, Mr. A. Trecul of France, and after him Dr. 
H. Poselger of Prussia, traversed Southern Texas and Northern Mexi¬ 
co, cqllecting many Cactacese, and increasing our knowledge of this 
interesting branch of botanical science. 
The Pacific Railroad expeditions since 1853 have opened fields not 
