ROSALES. 



225 



Genus PITHECOLOBIUM Martius. 



PiTHECOLOBIUM EOCENICfM BciTV, 11. S]). 

 Plalc XLV. fi-un-L'. 



Drscription. — Leaves even-])iuii;ite. witli ser- 

 er.il pairs of opposite leaflets, iucroasin<i in 

 size distad. Leaflets asyininetrie-ellipticnl in 

 outline, the apex rounded or l)luu(ly pointed 

 and the base euneate, inecpiilateral, sessile. 

 Lenjitli about .'3 eentimeters. Maxiinuiu width, 

 wliieh is in tlie niiddh' part of the lealiet, aliout 

 l.Ocentimetei-s. Margins entire. Texture cori- 

 aeeous. Petiolules wanting, the lealh^ts Ix'ing 

 seated dheetly and obliquely on the raehis. 

 Midrib stout, somewhat curved, becoming tl\in 

 distad. vSeeondaries thin, six or seven snl)- 

 opposite to alternate ]iairs, branching from tlie 

 midrib at angles of about 50° and jiursuing 

 a rather straight course to the marginal region 

 where thej' curve upward and are campto- 

 drome. Ai'eolation fine but distinct, com- 

 posed of four or five sided meshes. 



This species is based on detached leaflets and 

 hence the leaf habit is conjectural an<l is drawn 

 honx the existing species, with the leallets of 

 some of which the fossil is identical. A com- 

 parison with the foliage of the existing rain tree, 

 Pithecolohlum sainan Bentham, endemic from 

 Nicaragua to Brazil and widely planted as a 

 shade tree in tropical America and even in Asia, 

 will show the very great similarity between 

 the Eocene species and this and other of the 

 existing species. I have figured alongside the 

 fossil the leaflets of two existing species which 

 illustrate in a most striking way the paral- 

 lelism between this lower Eocene form and its 

 existing descendants. PifJiecolohium unguis- 

 cati (Linne) Bentham, sho\sai in Plate XL^^ 

 figure 4, is a small tree that forms thickets on 

 the Florida Keys, and is widely distributed 

 throughout the AiitUles to Venezuela and 

 Colombia. Pithecolobium dulce Bentham, 

 shown m Plato XLV, figure 5, is a large tree 

 which ranges from southern Mexico through 

 Central America to Colombia and is natni'al- 

 ized in many tropical countries. 



The genus Pithecolobium belongs to the 

 tribe Ingeaj of the Mimosaceis and is more or 

 less closely related to the genus Inga of Will- 

 denow. More than 100 existing species are 

 known, aD confined to the Torrid Zone, where 

 many of them are large trees. Three-fourths 

 of the existing forms are American, and there 

 50243°— 16 15 



ar(> more than a score in tropical Asia and a 

 few in tropical Australia and Africa. Witii tlie 

 exception of Pithecolobium tertiarum, described 

 by Engclhardt ' from the Tertiary of Bolivia, 

 and J'itlitciilobium tenuifolium described by 

 the same author = from the Tertiary of Co- 

 lombia,, the genus has not previously be(>n 

 itM.ognized in the fossil state. Tlio second of 

 these species is very similar to Pithecolobium 

 roccnicvm Bevvy and is com]iared by Ejigle- 

 hardt - with the existing Pithecolobium glo- 

 meratum of Colombia, Guiana, and Brazil. 



This species resembles somewhat Sophora 

 pokcolobifoliu Berry, a somewhat smaller form 

 tliat has a narrower apex and a more slender, 

 straighter mich'ib. 



Occurrence. — Lagrange formation (m beds of 

 Wilcox age), Pmyear, Henry County, Tenn. 

 (collected by E. W. Berry). 



Colhction. — U. S. National Museum. 



PiTiiFxoi.OBiiM oxFORDEXsis iicrry, n. sp. 

 Plate XLV. figure 3. 



Descnption. — Leaflets small, asymmetric- 

 ovate m outlme, the apex narrowly rounded 

 and the base inecpiilateral, euneate. Length 

 about 2.5 centimeters. Maxunum width, 

 which is below the middle, about 1.1 centi- 

 meters. Margins entire. Texture coriaceous. 

 Petiolules wanting, the leaflets being sessile 

 and oblique. Midrib stout, curved below, 

 straiglit distad. Secondaries thin, more or 

 less immereed, six or seven subparallel pah-s, 

 camptodrome. 



This species, which is based on detached 

 leaflets, differe from Pithecolobium eocenicum 

 in its much more asymmetric fonn, more 

 narrowed apex and base, and obsolete tertiary 

 system. It is also considerably smaller. It is 

 close to a number of existmg species of Pithe- 

 colobium, and among fossil forms it may be 

 compared with the lower Oligoceno species of 

 Europe that are usually referred to the genus 

 Pala^olobium of Unger, especially with the 

 numerous leaflets of Palseolobium haeringianum. 

 Unger,^ figured from liaermg in the Tyrol by 

 Ettingshausen.'' 



'Engplhardt, Hermann. Naturwiss. Gesell. IsLs in Dresden Abh.. 

 1894, p. 12. |)1. 1, fig. .Ti. 



2Engelhardl, Hermann, Scnckenbergische naturf. Gesell. Abh., vol. 

 19, p. 37, pi. 3, fig. 21, 1895. 



' Unger, Franz, Die (ossilc Flora vuii Solzka, p. .'iii. pi. 41 , figs. R-10, 18.50. 



' Ettingshausen, ('. von, Die tertiiirc Flora \ou Hiiring in Tirol, p. 88, 

 pi. 29, figs. 10-17, 1855. 



