COLEOPTERA OF SOUTHERN CALIFORNIA. 5 



Range. The principal chain, extending from the 

 Tejon to the Colorado River, has received various 

 local names, the central and highest portion being 

 known as the San Bernardino Mountains. Taken as a 

 whole, it is for convenience frequently referred to in the 

 following pages as the Southern Sierras. 



To the east of these mountains lie the Colorado and 

 Mojave deserts, while to the west the country is broken, 

 especially toward the coast, by numerous short ranges 

 of no great altitude, between which lie fertile valleys. 



The climate of Southern California varies much 

 according to locality, but it is in general mild and dry. 

 Along the coast the mean temperatures of January and 

 July differ by but little more than 10, but toward the 

 interior the difference between summer and winter tem- 

 perature becomes rapidly more marked. Except in the 

 higher parts of the mountains, the mercury rarely drops 

 below 28 Fahrenheit in winter, but not infrequently 

 rises to or even exceeds 100 in the summer months in 

 the interior valleys. The summers in the desert region 

 of the southeast are excessively hot, a temperature of 

 130 being at times experienced at Yuma and other 

 points along the lower Colorado River. 



In all parts of our territory the year is divided into 

 two well defined seasons, a rainy and a dry. The for- 

 mer usually begins toward the end of October and lasts 

 till April. During this season the fair days greatly out- 

 number the rainy ones, and the precipitation is on the 

 average less than that during any period of equal length 

 on the Atlantic slope. The average rainfall at Yuma is 

 less than 4 inches; at San Diego 10 inches; at Los 

 Angeles 20 inches, and becomes somewhat greater as we 

 ascend the western slopes of the mountains. Snow falls 

 every winter at altitudes of 3,000 feet and over, but 



