98 BAHIA BLANCA. [cHaP. Vv. 
surface. When frightened, it attempts to avoid discovery by 
feigning death, with outstretched legs, depressed body, and 
closed eyes: if further molested, it buries itself with great quick- 
ness in the loose sand. ‘This lizard, from its flattened body and 
short legs, cannot run quickly. . 
I will here add a few remarks on the hybernation of animals 
in this part of South America. When we first arrived at Bahia 
Blanca, September 7th, 1832, we thought nature had granted 
scarcely a living creature to this sandy and dry country. By 
digging, however, in the ground, several insects, large spiders, 
and lizards were found in a half torpid state. On the 15th, a 
few animals began to appear, and by the 18th (three days from 
the equinox), every thing announced the commencement of 
spring. The plains were ornamented by the flowers of a pink 
wood-sorrel, wild peas, cenothere, and geraniums; and the birds 
began to lay their eggs. Numerous Lamellicorn and Hetero- 
merous insects, the latter remarkable for their deeply sculptured 
bodies, were slowly crawling about; while the lizard tribe, the 
constant inhabitants of a sandy soil, darted about in every direc- 
tion. During the first eleven aays, whilst nature was dormant, 
the mean temperature taken frum observations made every two 
hours on board the Beagle, was 51°; and in the middle of the 
day the thermometer seldom ranged above 55°. On the ¢leven 
succeeding days, in which all living things became so animated, 
the mean was 58°, and the range in the middle of the day between 
sixty and seventy. Here then an increase of seven degrees in 
mean temperature, but a greater one of extreme leat, was suffi- 
cient to awake the functions of life. At Monte Video, from 
which we had just before sailed, in the twenty-three days included 
between the 26th of July and the 19th of August, the mean 
temperature from 276 observations was 58°.4; the mean hottest 
day being 65°.5, and the coldest 46°. The lowest point to 
wwhich the thermometer fell was 41°.5, and occasionally in the 
middle of the day it rose to 69° or 70°. Yet with this high 
temperature, almost every beetle, several genera of spiders, 
snails, and ‘larfd-shells, toads and lizards were all lying torpid 
beneath stones. But we have seen that at Bahia Blanca, which 
is four degrees southward, and therefore with a climate only a 
very little colder, this same temperature with a rather less ex- 
