tion. All size measurements are of the greatest dimension. 
Rhizophora L.* Grains from 11 to 80 yw in size, vary- 
ing in shape from subprolate to spheroidal to suboblate. 
Polar view circular to triangular in grains with gaping 
colpi. Tricolporate; ectexinous colpi crossed by colpi 
transversales or elongated into a colpus aequatorialis. 
Colpi transversales costate to varying degrees at edges. 
Exine less than 1 to ca. 2.5 w thick. Ectexine generally 
thinner than endexine except sometimes at poles. Ec- 
texine varies from smooth with very indistinct pattern 
to scabrate with distinct columellae. 
1. R. Mangle L.: Grains 11-28 p, spheroidal to sub- 
prolate; circular to triangular in polar view. Shape gen- 
erally well-defined and very regular, ranging from circular 
to oval with a slight equatorial bulge in equatorial view. 
Costae transversales well developed. Small grains psi- 
late; exines of large grains scabrate with distinct colu- 
mellae forming regular patterning in surface view. Colpi 
transversales of medium width. Plate XL, fig. 3. 
2. RB. samoensis Salv.: Grains 14-28 p, subprolate; 
nearly rhomboidal in equatorial view; grains mostly well 
formed, regular in shape. Costae colpi and costae trans- 
versales very narrow. Ectexinous colpi constricted at 
junction with colpus transversalis. Columellae not so 
distinct as in Rk. Mangle; ectexine psilate to very finely 
scabrate. Ectexine heavier at poles. 
3. BR. racemosa G. F. W. Meyer: Grains 15-26 p in 
breadth, typically oblate-spheroidal to suboblate; colpi 
transversales very narrow, often ragged. Grains tend to 
crumple more than do those of ?. Mangle L. Kctexine 
psilate and appearing almost structureless in most grains. 
Surface pattern indistinct. Plate XL, figs. 1 and 7. 
4. R. Harrisonu Leechm. : This description does not 
* Terminology from Erdtman (1952) and Faegriand Iversen (1964). 
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