174 STUDIES IN GEOLOGY, No. 4 



A considerable number of fossil species of Pithecolobium 

 have been described within the past few years. The existing 

 species number well over one hundred, all confined to the 

 tropics, and many of them large trees widely planted for 

 shade. Three-fourths are American, although there are 

 about twenty forms known from tropical Asia, and a few in 

 tropical Africa and Australia. In the present montafia region 

 of eastern Bolivia the upper limit of their range appears to 

 be about 1,500 meters, at which altitude one or more species 

 are found along the head waters of the Rio Chapare, a few 

 miles northeast of Pisllypampa, but at a much lower level, 

 and also throughout the valleys in the Sierras between Coch- 

 abamba and Santa Cruz de la Sierra. 



A distinct and somewhat smaller species is represented in 

 the Pliocene tuffs at Potosi, Bolivia, and a second South 

 American fossil species has been described by Engelhardt 18 

 from the Miocene of Colombia. 



Family OESALPINIACE7E 



Genus CASSIA Linne 



Cassia pisllypampensis Berry, sp. nov. 



PLATE VI Fig. 6 



Leaflets sessile, inequilateral, obovate in form, widest 

 above the middle. Apex rounded, mucronate. Base bluntly 

 pointed. Margins entire. One side of the lamina is full and 

 evenly rounded and the other is narrow and relatively straight 

 margined. Texture coriaceous. Midrib mediumly stout, 

 curved proximad. Secondaries thin, immersed; about six 

 pairs diverge from the midrib at angles of about 50 degrees, 

 ascending subparallel, and but slightly curved, ultimately 

 camptodrome. Tertiaries obsolete. 



This leaflet may be matched by various existing South 

 American species, in fact -I collected a species with similar 



18 Engelhardt, H., Abh. Senck. Nattirf. Gesell., Bd. 19, p. 37, 

 pi. 3, fig. 21, 1895. 



