132 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.54. 



the forms that I have seen Pithecolohium dulce Bentham of the West 

 Indies and northern South America, may be mentioned as a closely 

 similar form to Pithecolohium hrittonianum. In Bolivia the genus is, 

 so far as I know, found only east of the Andes in eastern Bohvia, where 

 the flora is essentially similar to that of the Amazon basin. P. 

 scalare, P. saman, and P. sopJioricarpum are found along the banks of 

 the Rio Piral, Rio Yapacani, and Rio Grande; P. scalare and P. 

 sopTioricarpum occur in the broken growth on the savannas of Santa 

 Cruz and the last named is a member of the subandean woode that 

 clothe the eastern slopes of the "CordiUera Real." 

 Eolotype.— Chi. No. 35140, U.S.N.M. 



PITHECOLOBILM TERTIARIUM Engelhardt. 



Pithecolohium ierliarium Engelhardt, Sitz. Naturw. Gesell. Isis in Dresden, 

 1894, Abh. 1, p. 12, pi. 1, fig. 33. 



Description. — Leaflets rhombic with truncated inequilateral apex 

 and an unknowm base. Margins entire. Texture coriaceous. Some- 

 what larger than Pithecolohium hrittonianum Berry and with a char- 

 acteristic Pithecolohium venation. 



This species was based upon a single fragmentary specimen and 

 is not contained in the present collections, and thus may be regarded 

 as of rare occurrence in the Phocene flora of Potosi. It was com- 

 pared by its describer with the existing Pithecolohium trapezifolium 

 Bentham of Colombia, Guiana, and Brazil. 



Genus MIMOSA Linnaeus. 



MIMOSA ARCUATIFOLIA Engelhardt. 



Plate 15, fig. 21. 



Mimosa arcuatifolia Engelhardt, Sitz. Naturw. Gesell. Isis in Dresden, 1894, 

 Abh. 1, p. 10, pi. 1, figs. 52-54. 



Description. — Leaflets small, sessile, linear-lanceolate, arcuate, 

 inequilateral, with a bluntly pointed apex and base, the latter 

 slightly wider than the apex. Margins entire. Texture subcori- 

 aceous. Length, 3 to 4 mm. Maximum width, in the middle part 

 of the leaflet, about 1 mm. Venation obsolete except for the thin 

 arcuate midrib. 



This species is fairly abundant at Potosi and occurs also at Corocoro. 

 It is distinguished with diflficulty from the smaller leaflets of the more 

 abundant Galliandra ohliqua, with which Engelhardt in all probabil- 

 ity confused it. The present species is, however, less linear, some- 

 what more slender and arcuate, with a less oblique base, and lacks 

 the three primaries of Calliandra ohliqua. According to Engelhardt 

 it is very similar to the existing Mimosa invisa Martins, which ranges 

 from southern Mexico and the West Indies to Brazil, or Mimosa 

 lupulina Bentham of the last region. It may also be compared with 



