Society, who by his kind attention greatly facilitated our
labor.
We are under deep obligations to Mr. Bentham, for much
important information, for. the privilege of consulting, his rich
herbarium, for many rare American plants, and especially for a
■ very full set of the plants collected by the late. Mr. Douglas in
Oregon and California, which were confided to him, as Secretary
of the London Horticultural Society, for distribution. .
To Dr. Lindley we are indebted for the opportunity of consulting
his very large herbarium,, for many authentic specimens,
and for valuable suggestions; ■
To Dr. Arnott our thanks are due for much very important
information, many valuable contributions to our. herbaria, and
for the privilege of consulting his own excellent" herbarium.'
To Prof. Don, for very obliging assistance in the examination
of the Linnaean herbarium.
To Mr. Lambert, for the facilities afforded us in examining
the plants, of Pursh, Bradbury, Mr. Nutt all, &c. which form a
part of his very large collection.
To Dr. Boott, for kind assistance in the determination of
the species of several difficult genera.
To Mr. Fraser, for the privilege of examining the herbarium
of Walter in his possession.
To Prof. Adrien de J ussiEu, for the opportunity of consulting
his own herbarium, and that of his distinguished father, which is
authentic for many species of Lamarck, Poiret, & c .: to his kind
offices also, as well as to Mr. Decaisne, Assistant Botanist in the
Museum of the Jardin des . Plantes, we are indebted for many
facilities in consulting the .vast collections of that establishment,
comprising the herbarium of Michaux, and many others of much
interest to the North American Botanist.
To Baron Benjamin Delessert, for access to his immense
herbarium and very complete botanical library. .
To Mr. P. Barker-Webb, for obliging assistance in the examination
of the North American plants of the .herbarium of Des-
fontaines, and the other collections which are incorporated in his
vast herbarium. Also to Mr. Spach, of the Jardine des Plantes,
for specimens V™any North American plants cultivated in that
establishment/ .
To Prof®E Candolle o f Geneva, for the important privilege
of freely/™sulting his larg® herbarium through all the families
w h i c f f i i r e now published in his Prodromus, and for duplicates
Gf puny interesting plants of the Order Compositæ.
j / T o Dr. E ndlicher, Curator, and Dr. F enzl, Assistant Curator
/o f the Imperial herbarium at Vienna, for assistance in consulting
that rich collection.
To Dr. Von Martius of Munich, and to Prof. Zuccarini, for
j access to the Royal Collections and Garden under their charge.
To Prof. S chlechtendal of Halle, for the privilege of consulting
his own herbarium, as well as that of Schkuhr, of which he
has charge, and for the communication of an interesting set of
Mexican plants.
To Dr. Klotszch, the Curator of the Royal herbarium at
Berlin, for the greatest attention in facilitating the examination
of the herbarium of Willdenow and the other rich collections of
that establishment ; and for his aid in procuring for us specimens
of American plants from the Botanic Garden.
To Prof. Kunth of Berlin, for the opportunity of consulting
his herbarium, with the view of comparing several North American
plants with species from Mexico and New Spain collected
by Baron Humboldt.
To Dr. T rinius and M. Bongard, of the Imperial Academy
of Sciences of St. Petersburg, for the communication of
many plants from Russian North America and the adjacent
Islands.
To Prof. Lehmann of Hamburgh, for the privilege of examining
the genera Potentilla, OEnothera, &c. in his herbarium, and
for many very interesting specimens in these and other genera :
also for a small collection of Greenland plants, made for the
most part by the younger Vahl.
To Mr. Nutt all we are indebted for a nearly complete
suite of the plants collected during his recent journey across the
Rocky Mountains to Oregon and California, accompanied with
manuscript descriptions of the new genera and species : also for
B