6 PROCEEDINGS OP THE NATIONAL MUSEUM vol. 66 



These leaves show the characteristic form and venation of the re- 

 cent leaves of the mangrove, from which they can not be differen- 

 tiated. 



On the whole the Rhizophora leaves may be distinguished from 

 those of the associated Mimusops by their being less coriaceous, with 

 slightly longer petioles, and by their regularity of form, being al- 

 ways at least pointed and never emarginate, and by their slightly 

 more prominent venation. For the most part they are preserved 

 as brownish impressions in the clays and not as black carbonaceous 

 films as are the bulk of those referred to Mimusops. I have gone 

 through all of the material of Rhizophora mangle in the National 

 Herbarium and aside from minor individual variations the leaves 

 are uniform in their characters, and never exhibit the peculiar varia- 

 tions shown in Mimusops. 



In the modern flora this species ranges on muddy tidal shores 

 from southern Florida and Bermuda through the Antilles and Cen- 

 tral America to Brazil, and from lower California to Ecuador. It 

 is the most specialized plant known for distribution by ocean cur- 

 rents. 



The genus appears in the fossil record in the early upper Eocene 

 in southeastern North America " and a second fossil species is known 

 from the Miocene of Venezuela.^ Two Oligocene-Miocene species 

 have been recorded from southern Europe. 



Plesiotypes.—C2ii. Nos. 37022-3, U. S. N. M. 



Order EBENALES 



Family SAPOTACEAE 



Genus MIMUSOPS Linnaeus 



MIMUSOPS PREDUPLICATA. new species 



Plate 2, figs. 1, 3, 5 ; plate 3, fig. 5 ; plate 4, figs. 2, 3 4 



This is an exceedingly interesting species and vies with the leaves 

 of the mangrove in its abundant representation in the Oropouche 

 clays. A considerable number of leaves showing the variety and ex- 

 tremes of its mutations have been figured. In general the leaves are 

 elliptical in outline, with broadly rounded, emarginate or retuse tips, 

 and rounded slightly pointed or cuneate bases. The petiole is short 

 and extremely stout. The margins may be evenly rounded but are 

 very frequently emarginately incised into a greater or less number of 



6 Berry, E. W., U. S. Geol. Survey Prof. Paper 84, p. 144, pi. 29, figs. 1, 2, 1914. 

 • Berry, E. W., Proc U. S. Nat. Mus., vol. 59, p. 576, pi. 109, fig. 4, 1921. 



