i68 STUDIES IN GEOLOGY, No. 4 



number of species ranging from Costa Rica through Colom- 

 bia over the Orinoco and Amazon basins and extending 

 southward east of the Andes along the headwaters of the 

 Amazon system to Bolivia. It is common in the Yungas 

 region and elsewhere in eastern Bolivia. 



D'Orbigny many years ago described the magnificent 

 palms in the Yuracare country around the headwaters of the 

 Rio Chapare and Rio Chipiriri, some 150 kilometers north- 

 east of Cochabamba, or about 75 miles northeast of Pislly- 

 pampa. These occur at elevations of from 3,000 to 5,000 

 feet and comprise Iriartea along with other palms, and such 

 other genera as Erythrochiton, Heliconia, Costus, Schmide- 

 lia, Erythrina, Psychotria, Cordia. Ficus, Hiraea, Pithecolo- 

 bium, Blechnum. and various additional Leguminosse and 

 Lauraceas. Eastward from Cochabamba the country is at 

 present somewhat drier than to the northward, and in the 

 former region one encounters what is largely brush vege- 

 tation on the mountains and forest in the valleys below about 

 5,200 feet. Iriartea e.vorrhiza and Iriartea phccocarpa are 

 not uncommon below this altitude in the country between 

 Cochabamba and Santa Cruz de la Sierra. 



A magnificent but undescribed fossil species of Iriartites 

 occurs in the lower Miocene (coal measures) of southern 

 Chile (Concepcion-Arauco district). 



Order URTICALES 



Family HORACES 



Genus COUSSAPOA Aublet 



Coussapoa pliocenica. Berry, sp. nov. 



PLATES TV and V 



Leaves ranging from small to large size, ovate-cordate in 

 general outline, widest medianly. tapering upward to the 

 bluntly pointed tip and downward to the cordate and often 

 slightly perfoliate base. Margins entire, slightly undulate in 

 the apical half of the leaf. Texture coriaceous, the lower 



