PHYSICAL CONDITIONS AND AGE INDICATED BY FLORA OF ALUM BLUFF FORMATION. 



49 



temppraturos entirely sufficient to explain the 

 extinction of Artocurpus on the mainland, but 

 not offering u satisfactory explanation of its 

 failure to survive in more southern latitudes. 



Occurrence: Alum Bluff formation, Alum 

 Bluff, Liberty County, Fla. (collected by E. W. 

 BeiTv). 



Collection; United States National Museum. 



Order CHENOPODIALES. 

 FamUy NYCTAGINACE.«;. 

 Genus PISONIA Linne. 

 Pisonia apalachicolensis Berry, n. sp. 



Plate X, figure 1. 



Leaves of relatively large size for this genus, 

 obovate in general outline, with a ])road apex, 

 which is evenly rounded or bluntly pointed, and 

 a gradually n.irrowed, sharply cuneate base. 

 Length about 5.75 centimeters; maximum 

 width, above the middle, about 2.4 centimeters. 

 Margins entire. Texture coriaceous. Petiole 

 short and stout, about 6 milhmeters in length. 

 Midrib stout but immersed in the thick leaf 

 substance, curved. Secondaries entirely im- 

 mersed and obsolete. 



The modern species of Pisonia are numerous; 

 they occur cliiefly in the Tropics in both hemi- 

 spheres and are largely coastal types. They are 

 abundantly developed in Central America and 

 tropical South America, and several species 

 occur in the AVest Lidies and Antilles. About 

 15 fossil species have been described, the ear- 

 liest recorded being from the Upper Cretaceous 

 of both America and Europe. The lower 

 Eocene of southeastern North America has fur- 

 nished two well-marked species, there is a spe- 

 cies said to be represented by both leaves and 

 fruit in the basal Eocene of the Rocky Moun- 

 tain area, a fourth species occurs in the Clai- 

 borne group, and a filth has been found in the 

 Jackson. Perhaps the most similar fossil form, 

 based on both leaves and fruits, is Pisonia 

 eocenica Ettingshausen,' from the lignites of 

 Haering, in Tyrol, which is upper Eocene or 

 lower Ohgocene in age, occurring also as early 

 as the Lutetian of England. 



Among existing species several are close to 

 the present form. Pisonia lon/jifolia Sargent, 

 of the beaches and shores of lagoons from the 



' Ettingshausen, Constantin, Die tertiiire Flora von Baring in Tirol, 

 p. 43, pi. 11, figs. 1-22, 1853. 



Florida keys through the West Indies to Brazil, 

 is very similar to Pisonia apalachicolensis, 

 though only about two-tliirds as large. 



Occurrence; Alum Bluff formation, Alum 

 Bluff, Liberty County, Fla. (collect(>(l by E. W. 

 Berry). 



Collection: I'lii'od Slates National Museum. 



Order ROSALES. 



Family CSSALPINIACEjE. 



Genus CiESALPINIA Linnfi. 



Csesalpinia sellardsi Berry, n. sp. 



Plate IX, fi-mros 1, 2. 



Leaflets small, sessile, inequilateral, ellipti- 

 cal in outUne, 7.5 millimeters in length and 

 4.2 miUimeters in greatest width. Apex 

 broadly rounded. Base strongly inequilater- 

 ally truncated, one margin ascending and the 

 opposite margin subauriculate. Midrib slen- 

 der. Secondaries two or more, slender, ascend- 

 ing, camptodrome. Margins entire. 



This species, which is obviously new, is 

 clearly the leaf of some shrub or tree of the 

 family Csesalpiniaceae. Though only a few 

 specimens were observed, this can not be 

 considered as indicating scarcity, for the plant 

 material at Alum Bluff is all rather meager 

 and poorly preserved. It seems probable that 

 the present species was a mem~ber of the 

 strand flora, the strand being the habitat 

 preferred by a number of species of this genus 

 in the modern tropical American flora. 



The fossil species may be compared with a 

 number of existing species, with which it 

 shows a very close agreement. Among pre- 

 viously described fossil species it is very close 

 to what has been identified by Schenk - as 

 Ciesalpitna townslundi Heer, from the Stampian 

 of Sieblos, originally described by Heer ^ from 

 the Aquitanian and Tortonian of Switzerland 

 and Baden and identified by Geylcr from the 

 Messinian of Sicily. 



There is a very notable display of Mimo- 

 sacese and Ciesalpiniacene in the flora of the 

 WUcox group, and these elements probably 

 continued to lie prominent throughout the 

 remainder of the Eocene and the Oligocene, 



2 Schenk, August, in Zittel, K. A., Handbuch der Palaeontologie, 

 Atith. 2, Palaeophytologie, p. 700, fig. 369 (4), ISiK). 



' Heer, Oswald, Flora tertiaria Helvetife, vol. 3. dI. 137, figs. 26-37, 

 1M9. 



