134 
TtrlTtrEES OJ? THE LT.AKOS. 
pean frog, lizard, sand-martin, and marmot. If the hibernal 
lethargy be observed, both in cold-blooded and in hot- 
blooded animals, we shall be less surprised to learn, that 
these two classes furnish alike examples of a summer-sleep. 
In the same manner as the crocodiles of South America, 
the tanrecs, or M adagasear hedgehogs, in the midst of the 
torrid zone, pass three months ot the year in lethargy. 
On the 25th of March we traversed the smoothest part 
of' the steppes of Caracas, the Mesa de Pavones. It is 
entirely destitute of the corypha and moriche palm-trees. 
As far as the eye can reach, not a single object fifteen 
inches high can be discovered. The air was clear, and the 
sky of a very deep blue ; but the horizon reflected a livkl 
and yellowish light, caused no doubt by the quantity of 
sand suspended in tlie atmosphere. AYe met some laige 
herds of cattle, and with them flocks of birds of a black 
colour with an olive shade. They are of the genus Croto- 
phaga* and follow the cattle. We had often seen them 
perched on the backs of cows, seeking for gadflies and other 
insects. Like many birds of these desert places, they tear 
so little the approach of man, that children often catch them 
in their hands. In the valleys of Aragua, where they are- 
very common, w:e have seen them perch upon the hammocks 
on which we were reposing, in open day. 
We discover, between Calabozo, Untucu, and tlie Mesa 
de Pavones, wherever there are excavations of some feet 
deep, the geological constitution of the Llanos. A formation 
of red sandstone (ancient conglomerate) covers an extent 
of several thousand square leagues. We shall find it again 
in the vast plains of the Amazon, on the eastern boundary 
of the province of Jacn de Bracamoros. This prodigious 
extension of red sandstone in the low grounds stretching 
along the east of the Andes, is one of the most striking 
phenomena I observed during my examination of rocks i» 
the equinoctial regions. 
The red sandstone of the Llanos of Caracas lies in » 
concave position, between the primitive mountains of the 
shore and of Parime. On the north it is backed by the 
* The Spanish colonists call tlie Crotophaga ani, zamurito (little car- 
rion vulture, Vultur aura minuta), or garapatero , ‘ the eater of V* 1 ’*" 
p*.as,’ insects of tlie Aearus family. 
