PLIOCENE PISLLYPAMPA BOLIVIA 171 



1891 referred 16 a fossil leaf from the lower Miocene of 

 Coronel, Chile, to this genus but the material is very incon- 

 clusive and his identification is hence of doubtful validity. 

 Typical forms are also present in the upper Miocene of the 

 Isthmus of Tehuantepec in southern Mexico, which will be 

 described in the near future. 



Order CHENOPODIALES 

 Family NYCTAGINACE^ 



Genus PISONIA Linne 

 Pisonia pliocenica Berry, sp. nov. 



PLATE VIII Fig. i 



Leaves of medium size, elliptical or obovate in general 

 outline, shortly pointed or rounded at the apex, slightly de- 

 current at the base, widest in the middle, one side of the 

 lamina often slightly wider than the other. Margins entire. 

 Texture coriaceous. Length about 5 cm. Maximum width 

 about 2.75 cm. Petiole relatively long, stout, curved, about 

 1.3 cm. long. Midrib stout, prominent on the lower surface 

 of the leaf, slightly curved. Secondaries thin, about five op- 

 posite to alternate pairs diverge from the midrib at angles 

 of from 45 to 50 degrees, and are camptodrome. The ter- 

 tiaries are thin and partially immersed in the leaf substance, 

 but are well marked, forming an open mesh internally, and 

 characteristically disposed arches in the marginal region. 



The present species is exceedingly like the existing widely 

 distributed strand plant, Pisonia aculcata Linne. It is also 

 very close to a number of other existing species which have 

 been described from Brazil, but with an undetermined range. 

 Among previously described fossil forms the present species 



16 Engelhardt, H., Abh. Senck. Natnrf. Gesell., Bd. 16, p. 649, pi. 

 3, fig. 2, 1891. 



