natives there toward the amber probably also contributed 
to lack of previous recognition. Invertebrate paleontolo- 
gists at Berkeley since 1956 and stratigraphers at the 
University of Lllinois since 1961 have been studying the 
geology of the amber-bearing beds in the Simojovel re- 
gion in order to establish the age of deposition of the 
amber as a context for evolutionary studies of the in- 
cluded fossils. Various phases of botanical investigations 
of the amber and of the beds containing it were begun 
in 1962 at Harvard University and extended to include 
chemical aspects in 1963. Thus, the study of the Chiapas 
amber has been approached from the standpoint of co- 
ordinating data from several disciplines that may shed 
light on mid-Tertiary ecosystems in southern Mexico. It 
has, furthermore, provided an opportunity to understand 
more fully the natural production of large quantities of 
resin and sites that favor its accumulation and subse- 
quent deposition in sediments under tropical conditions. 
Pollen analysis of the Chiapas amber-bearing beds is 
of particular interest in any attempt to determine some 
of the vegetational and general environmental conditions 
that could have existed at or near the site of deposition 
of the amber. Study of 12 samples from amber-bearing 
strata in various localities indicates that the primary de- 
positional environment of the amber was dominated by 
mangrove vegetation comprised of several species of 
Rhizophora. Although numerous other microspore types 
occur in these sediments, this report will be restricted 
essentially to a discussion of Rhizophora, with brief men- 
tion of associated pollen types which were strikingly 
abundant or otherwise significant to an understanding 
of the ecology of vegetation at or near the depositional 
sites of the Chiapas amber. The record of occurrence of 
Rhizophora pollen in these strata contributes also to our 
knowledge of the distribution and ecology of mangrove 
[ 291 ] 
