The two samples from Palo Blanco (VIII and IX) are 
generally similar. Sample VIII is from the bed imme- 
diately underlying that of Sample IX and appears to 
contain no Rk. Mangle-type, and though there is much 
uncertainty about the affinity of many individual grains 
due to poor preservation, it is improbable that a signifi- 
cant number Rk. Mangle-type have been overlooked. 
Engelhardtia-ty pe makes up 22% of the total recogni- 
zable pollen. The genus Engelhardtia today is restricted 
to the highland areas of Mexico and Central America 
(Miranda and Sharp, 1950), and to southeast Asia, where 
it is common in the hills of coastal regions (S. Hu, pers. 
comm., 1965). The abundance of grains of this type in 
the Chiapas sediments (and in other early Tertiary sedi- 
ments, cf. Traverse, Hngelhardtia Spackmani) suggests 
either that the grain represents an extinct line with pol- 
len very similar to the modern Hngelhardtia, or that the 
genus has changed both its range and ecological prefer- 
ence in the New World since the Oligo-Miocene. Sample 
IX contains a small percentage of unmistakable Rhizo- 
phora Mangle-type pollen and a number of Rhizophora 
affinity uncertain grains which belong probably to R. 
Mangle and also 7% Engelhardtia. The matrix of both 
samples contained glauconite and marine fossils. ‘The 
high percentage of Rhizophora pollen and the presence 
of fungal spores suggest deposition in the vicinity of 
mangrove vegetation. There is some carbonized material 
which might result from re-deposition of older material, 
as is known to occur in levee deposits in the Orinoco 
delta (Muller, 1959). However, percentages of Rhizo- 
phora and other small, light pollen are known to increase 
also in sediments quite distant from shore. Most of the 
grains encountered in these sediments are in the 20-40 yu 
size range and indicate possibly an offshore depositional 
environment. 
[ 318 | 
