Special attention has been devoted to the Zoological work of the 
~ expedition, in which connection some very interesting discoveries were made. 
Detailed scientific papers on the Mammals and Insects collected have been 
embodied in Appendices (II.—V.); but as the collections of Birds and Cold- 
Blooded Vertebrates contain no new species, scientific descriptions are not 
necessary, though the reader will find Chapters dealing in a more or less 
popular way with both these branches of Biology, as well as a review of the 
whole Biological work. 
The Meteorological observations will be found in tabulated form 
(App. VI.), interesting points concerning the climatic conditions of the 
country being detailed in Chapter XV. An attempt, too, has been made to. 
give a general sketch of the Geology of the country passed through. 
The photographs and coloured plates which illustrate the book, have been 
chosen with a view to presenting different types of natives, geological 
formations, scenery, and other matters of general interest. It is unfortunate 
that, owing to the necessity for a distribution of the plates throughout the 
volume, these cannot always fall at—or even near—the mention of them in 
the text; but, as far as possible, references are given where they illustrate 
places visited or explain points raised, as, for example, in the Chapters on 
Natural History and Geology. 
We take this opportunity of acknowledging our debt of gratitude to the 
British War Office for lending the services of Captain H. E. M. Douglas, 
V.C., D.S.O., R.A.M.C.; and to the Survey of India for those of Hazrat Ali, 
our surveyor, whose sad death in the performance of his duty is so deeply 
regretted by every member of the expedition. 
Out best thanks are also due to the Hon. N. Charles Rothschild, M.A., 
F.L.S., for the paper on Siphonaptera; to Mr. H. R. Hogg, M.A., F.Z.S., for 
his contribution on Araneidae; to the members of the British Museum Staff, 
who kindly examined and classified the specimens belonging to the orders of 
Invertebrates contained in the collection; to Mr. Gerrit S. Miller, of the 
Smithsonian Institution, for his description of five new species in the collection 
of Mammals; and to the Rey. Frank Madeley for his assistance in connection 
with the history of the moundsand monuments examined round about Hsi-an Fu. 
Major L. D. Fraser, Royal Artillery, afforded invaluable assistance in 
undertaking the preparation of the Map, in correcting the spelling of Chinese 
(ii) 
