P E E F A C E. 
ORIGIN AND CHAEACTER OF THE WORK. 
This volume consists of those parts of the eleventh of the Pacific Railroad Reports, which describe 
the natural condition and products of the country traversed by the Surveying- Expedition near the 
41th and 49th parallels of latitude. It contains also, much respecting the adjacent regions, including 
Minnesota, Nebraska, Kansas, Oregon, California, and Washington Territory, with the British posses- 
sions to the North, all of which were visited by the naturalists of the expedition. 
The Meteorological chart together with the first part (Chapter IV. of the Government edition), 
will serve in some degree to show the general features of these countries, together with their climate. 
Prefixed to the catalogues of plants, is a description of the physical outlines of the surface and geogra- 
phical distribution of species in Washington Territory, witli full accounts of the forests and trees. 
Parts II. and III. contain descriptions of sixty-four species of Mammals, two hundred and fourteen 
Birds, thirty-four Reptiles, sixty-six Fishes, three Mollusca, seven Crustacea, one hundred and ninety 
Insects, and eleven Plants. Of these, one hundred and seventy descriptions have never befoi-c been 
published, and ninety others, were first described from specimens collected by this Expedition. Besides 
these, there are noticed more or less fully, about ninety species of Mollusca, and seven hundred and fifty 
Plants. The names of new species (excepting Insects), will be found in the table of contents, where are 
also inserted the names of families accidentally omitted in printing the work, with references to the first 
genus included in each. 
The report on Insects is wholly the work of the distinguished entomologist Dr. J. L. Le Conte, of 
Philadelphia, who has added in an appendix the latest discoveries in that department. 
In the other branches of Zoology, the exact technical descriptions are borrowed from those of Prof. 
Baird, Mr. Cassin, and Mr. Lawrence, in vols. VIII. and IX. Pacific Railroad Reports (Mammalia and 
Birds) and by Dr. Girard in vol. X. (Pishes). Those of Reptiles were chiefly taken from Dr. Girard's 
report on the collections of the Exploring" Expedition, and the Smithsonian catalogue of serpents, while 
many are the original work of that zealous and accurate naturalist, Mr. Robert Kennicott. These have 
been copied verbatim in many cases, while in others slight corrections and additions have been made, 
authorized by the observations of the naturalists in the field. Thus many original measurements are 
added, and with the fish and reptiles, the colors, rvhile living, substituted for those of dead specimens 
faded by alcohol. Other alterations are noticed in the appropriate places. The descriptions of Crustacea 
are condensed from Mr. Wm. Stimpson's monograph in the Journal of the Boston Society of Natural 
Histoi'y, vol. VI. The new plants are described by Profs. Torrey and Gray, and the Mollusca, by Mr. 
Wm. Cooper. 
In the work of preparing the reports, the invaluable facilities afforded by the vast Government 
collection, and the fine library of the Smithsonian Institution, have been freely granted by its learned 
Secretary, Prof. Henry. There, also, are deposited the specimens upon which the descriptions here given 
were based. 
