G20 



the Cordilleras of New Grenada, bordering the 

 steppes on the west. Does the want of frag- 

 ments of granite, gneiss, and porphyry, and the 

 frequency of petrified wood % sometimes dico- 

 tyledons, indicate that those sandstones belong 

 to more recent formations, which fill the plains 

 between the Cordilleras of Parime and the 

 shore, as the molassus of Switzerland fills the 

 space between the Jura and the Alps ? I dis- 



8° 59' 36"; Pamplona, 7° 17' 3". The following are the 

 names of the towns which MM. Boussingault, Rivero, and: 

 myself have observed at different epochas, but not always 

 in the same settlements. The first latitude is that which I 

 have published ; the second, that of the two travellers I have 

 just named j Caraccas, 10° 30' 50" j 10° 30' 58"; Valencia, 

 10° 9' 56* ; 10° 10' 34" : Villa de Cura, 10o 2' 47" j 10° 3' 

 44\; S. Juan de los Morros, 9° 55' 0* ; 9° 55' 50" : Honda, 

 5° 11' 45" ; 5° 11' 20" : M. Boussingault estimates the lati- 

 tude of Merida 8° 16' 0". 



* The people attribute those woods to Bowdichia virgil- 

 io'ides or Alcornoco, (See my Nova Gen. and Spec. Vol. iii, p. 

 377), and to Chapara Bovo (Rhopala complicata) . It is be- 

 lieved in Venezuela, as in Egypt, that petrified wood is form- 

 ed in our times. I shall here observe that I found this de- 

 cotyledon petrified wood only at the surface of the soil, and 

 not inclosed in the sandstone of the Llanos. M. Caillaud 

 made the same observation in going to the Oasis of Siwa. 

 The trunks of trees 90 feet long, inclosed in the red sand- 

 stone of Kifhauser (in Saxony), are, according to the recent 

 researches of M. de Buch, divided into knots, and are cer- 

 tainly monocotyledons. 



