35. ZOOLOGICAL RESULTS OF THE PERCY SLADEN 
TRUST EXPEDITION TO YUNNAN UNDER THE 
LEADERSHIP OF PROFESSOR J. W. GREGORY, 
F.R.S. (1922) 
INTRODUCTION. 
By Pror. J. W. Greeory, F.R.S. and C. J. Grucory, B.Sc. 
The problems of South-Eastern Asia require for their 
solution the combined help of the zoologist, botanist, 
geographer and geologist ; for the determination of the former 
extension of the lands and mountain chains, and the dates 
of the regional uplifts depends on the distribution of animals 
and plants as well as on the geological structure and geo- 
graphical grain of the existingland. While many biologists ho!d 
that the ocean basins have lasted throughout geological time 
the general opinion amongst geologists is that the Indian 
Ocean occupies the site of a continent which existed until, 
geologically speaking, a modern date. The subsidence of that 
land on the formations of the Indian Ocean weakened the 
Plateau of Equatorial Africa. which, during the periods of 
Seological time from the Cretaceous to the present day, was 
roken by north to south fractures that formed the. rift 
valleys, sunken basins, and colossal lava fields of Eastern 
Africa. Corresponding developments may be expected to 
occasions p] a journey to areas in South-Eastern Asia 
ere features corresponding to the tectonic valleys of Kast 
Africa may exist t length in 1922 an opportunity to carry 
out this project became possible. It was aided by a grant 
from the Percy Sladen Memorial Trust and was therefore one 
of which was geologically and some of it geographically 
unknown. The special problem of the expedition to 
eastwa ° 
the Himalaya into Central and North-Eastern China, as 
was held by the late Prince Kropotkin and A. Little, o 
