98 BAHIA BLANCA. [chap. v. 



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, Oenotheras, 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 days, whilst nature was dormant, 

 the mean temperature taken from 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 eleven 

 succeeding days, in which all living things became so animated, 

 the mean Mas 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 heat, 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 

 which 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 land-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- 



