][96 NATURAL HISTORY BULLETIN 



Barometric Pressure. This was measured by an aneroid bar- 

 ometer. 



Bain-fall. No effort was made to measure the rainfall, but 

 during August and September, 1908, when these observations 

 were made, Mr. Glenn H. Stern reported the rainfall at Logan, 

 eight miles away, as follows: 



August 2.03 inches. 



September .79 inches. 



This also probably approximately measured the rainfall at 

 Missouri Valley, and by far the greater part of this was precipi- 

 tated during the first half of August, which was decidedly rainy. 

 The latter half of August and the first half of September were 

 very dry. By the middle of September the hills were dry and 

 brown, and in the more exposed places only a few of the more 

 pronounced xerophytes were in flower. The following were ob- 

 served in flower at that time near stations 1 and 3 : 



Aster oblongifolius 



Aster sericeus 



Chrysopsis villosa 



Grindelia squarrosa 



Helianthus scaberrimus 



Kuhnia eupatoroides var. corymbulosa 



Liatris punctata 



Solidago rigida 



Solidago speciosa var. angustata 



By this time even the leaves on the buroaks curled, and during 

 the day most plants which still retained leaves were wilted. 



The Stations. 



Four stations were selected for the observations : 

 Station 1 was located at an elevation of 140 feet above the al- 

 luvial plain on the west side of the ridge forming the bluffs of 

 the Missouri valley just above Missouri Valley. It was fully ex- 

 posed to the southwest and west, but was somewhat sheltered by 

 the ridge to the south and southeast. Its vicinity was covered 

 with a typical prairie flora. This station, with some of the ap- 

 paratus in place is shown in the foreground in plate VIII, figure 

 1, looking south, and at the point marked 1 in plate IX, figure 1, 

 looking east. 



