184 KELATIOX BETWEEN CLIMATE AND VEGETATION 



stubble, and soon afterwards I entered the town with as many 

 of my things as had escaped the accidents of this long and 

 perilous journey. 



One reason I had for going to the south of Bolivia was to look 

 after some deposits of fossil bones which were reported to exist 

 thereabouts ; and the four months which I passed there were em- 

 ployed principally in endeavouring to find them..* 



I had intended to proceed to the Republic of Paraguay, cross- 

 ing the plain I before mentioned as the Gran Chaco, and which 

 extends from the borders of tlie Rio Paraguay to the confines of 

 Bolivia. The route which I am about to describe was under- 

 taken with this view, but I was afterwards compelled to abandon 

 it, in consequence of the failure of the Bolivian Government to 

 render the assistance they had promised me. 



With the above ideas I left Tarija on the 4th of June, 1846, 

 for the Chaco, distant about sixty leagues to the east. My 

 course lay along the Rio de Tarija, a tributary or the source of 

 the Rio Vermejo, to Santa Ana, where there are some fine vine- 

 yards. From this place the road rises over vast, monotonous, 

 and naked pasture land, on which I found but two plants in 

 flower on the banks of a small rivulet, an Epilobium and a 

 Rush. This region, known by the name of Puna de PoUa, is 

 not of very great extent ; it forms a sort of barrier between the 

 temperate district of Tarija and the tropical cantons which are 

 further on. 



Tlie first trees I met with on the steep declivity which led to 

 a warmer climate were Alders ; they grew in snow ; the first I 

 had seen for three years. In the beautiful valley of Narvaes are 

 large forests broken by fine prairies extending as far as San 

 Luis, about 30 leagues from Tarija. From the neighbourhood of 

 San Luis I brought away nearly 60 species of forest trees. Un- 

 luckily few were either in flower or in fruit. The greater number 

 consist of Leguminous plants ; one of the commonest is an 

 Acacia {A. Angico) found throughout tropical America, and the 

 bark of which is used for tanning leather ; it is called Angico in 

 Brazil, and Bilca or Sevil in Bolivia. The finest timber is fur- 

 nished by the Cedro {Cedrela Brasiliensis), the Soto, the 

 Quina-quina, the Laurel (a species of Laurus), and the Nogal 

 {Rhus juglandifolium). Here too are found a Pisonia (Zapallo) , 

 a Bugainvillea (Huancar), a Luhea (Membrillo), several 

 Myrtle-blooms (Barroso, Goyavo), Bignoniads (Tarco, Lapacho 

 morado, Lapacho amarillo, &c.), a Xanthoxylum (Suiquilo),two 



* I sent to the Paris Museum the fossil remains of fourteen mammals 

 found in the alluvia of Tarija, amongst which were two species of mastodon, 

 a mylodon, a megatherium, a horse, several ruminants, and other species, 

 for the most part new. 



