clay and red sandstone of a rather friable nature . 
The mountains are very precipitous as a rule,due to 
the friable nature of the formation. The bench lands 
a^^eing eroded very rapidly and lost completelj'" to 
cultivation of any sort,not even grass can get-a 
foothold. The dry season is so long the the season 
of grov/th is very short,from Hoveraber to April, only. 
Heavy frosts,combined with the long dry season, in the 
winter months capse almost all trees to^ drop their 
leaves and during September and October the forest 
is every\¥here dry and leaf less, except, along the margin 
of the stresims in sheltered places. 
Sight days were spent here,six days in actual collects 
ing. 192 specimens were collected consisting of 82 
species, of which 2"^ were new for the year and 10 not 
previously taken in Bolivia. 
. The bird fauna here is a mixture of the species 
taken -at all stations from San Lorenzo to Fortin 
Campero,even several from Oploca were taken here. 
(Pitangus sulphuratus;Serpophaga subcristata; 
Phytotoma rutila;Catamenia analis;Molothrus badius 
and Molothrus bonariensis,also .Goiirabin pcui and 
Zenaida auriculata). San Lorenzo was represented by 
20 species;La Merced by 10;Hio Lipeo by 17;Veimiejo by 
4 species and Fortin Campero by 4 species. 
The fauna of the op^n lands of the valley is ver 
distinct from that of the forest,those of the forest 
being largely those taken at Rio Lipeo and Bermejo, 
while those of the open represent more those of San 
Lorenzo and La Merced. 
In addition to the species collected,50 others were 
observed (see list). Of these 30,8 species have not 
up to now-been collected (starred in list) 
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