402 ANNUAL EEPOET SMITHSONIAN INSTITUTION, 1918. 



Mississippi States, as well as in the Southern States bordering the 

 Gulf of Mexico. 



This early Tertiary flora consisted of familiar hardwoods, such as 

 willow, gum, cottonwood, sycamore, oak, walnut, hickory, etc., asso- 

 ciated with figs and palms, and numerous exotic types, such as cam- 

 phor, breadfruit, sterculia, bauhinia, etc., that have since become 

 extinct on this continent but still survive in other regions. Sequoia 

 still flourished as far east as Dakota and along the Mississippi Gulf, 

 and its ferruginized cones are abundant at some Eocene horizons, while 

 the clays contain profuse impressions of its foliage. At this time 

 (Eocene) the Gulf of Mexico extended northward beyond the mouth 

 of the Ohio and its shores were clothed with a wonderfully varied 

 flora containing numerous migrants from the Tropics, such as bread- 

 fruit, custard apple, soapberry, rain tree, alligator pear, mangrove, 

 fiddlewood, devilwood, persimmon, dilly, iron wood, mastic, button- 

 wood, stopper, buckthorn, wild lime, redbud, cocoa plum, sea grape, 

 and many acacias and mimosas. Among these were forms like the 

 Nipa Palm, distributed by ocean currents, and now confined to the 

 littoral of southeastern Asia. 



Engelhardtia is a tropical genus of trees belonging to the walnut 

 family, but, unlike the walnuts and hickories, the seed part of the 

 fruit has remained small, thus facilitating the production of a large 

 number of seeds. The bracts, which are inconspicuous in the walnut, 

 have become enormously enlarged in the Engelhardtias, so that each 

 seed has three large wings to aid its dispersal. In our lower Eocene 

 the oldest known representative of these trees shows the initial type 

 of the winged fruits, so much more primitive than Engelhardtia that 

 it is referred to a new genus named Paraengelhardtia. Associated 

 with Paraengelhardtia are true Engelhardtias, also the oldest 

 known, and both new to the Western Hemisphere. The modern forms 

 number about a dozen, and all but one of these are confined to the 

 Orient, where they range from the northwestern Himalayas through 

 farther India and Burma to Java and the Philippines. One form, 

 probably a descendant and relic of this abundant Eocene display 

 in the Mississippi embayment region, is still found in the mountains 

 of Costa Rica, and a considerable number are found in the upper 

 Eocene and later Tertiary of central and southern Europe. 



The winged fruits of Engelhardtia and its ancestor, Paraengel- 

 hardtia are shown in figure 39 (plate 6). 



Among the leguminous trees, already mentioned as being very 

 abundant, are numerous species of the coral bean, Sophora. evidently 

 strand types, and one of these, which was exceedingly abundant in 

 west Tennessee, is scarcely to be distinguished from the existing cos- 

 mopolitan strand plant of the Tropics, Sophora tomentosa. 



