An Analysis of Filtered Water — Dodtje. 69 



eral species of Poa^ Beckmaniila eriicce/onnis, Host., Schedotmardus 

 Texanus^ Stend., Eriocoma cuspidata^ Niibt., and several species 

 of Triticum^ complete the list of grasses collected. 



Only two species of ferus were observed,a Woodma and Pellcea 

 atropurpiirea^ Link., the latter growing in the crevices of the 

 rocky ledges on the summit of the biittes. A few mosses were 

 seen, and two species of lichens. 



The arboreal vegetation was, as might be supposed, very 

 scanty. Aside from the timber on the Missouri river bottoms, 

 only a few stunted willows, cotton-wood, box-elder and June berry 

 were found scattered at intervals along the streams. 



A curious feature of the country west of the Missouri, beyond 

 the limit of the drift, was the great number of fossil tree stumps, 

 protruding through the sod. Hundreds could be counted in many 

 places, and in some localities, especially in Pyramid Park, the fos- 

 sil trunks were found where they had fallen, almost whole and 

 but little the worse for the ravages of time. There is no doubt 

 that during the Cretaceous and Tertiary periods extensive forests 

 flourished in this region; and to judge from the size of the stumps 

 remaining, some of the trees must have been of immense size. 

 Many stumps were seen ten feet or more in diameter, and I heard 

 of others still larger. 



This region will yet prove a mine of wealth to the botanist 

 studying our fossil flora. Fossil leaves in great abundance occur 

 ev^erywhere in the Tertiary sandstones and soft Cretaceous clays. 

 In some places the clay beds were originally underlain by seams of 

 lignite, which have been burned, baking the clay above into a 

 kind of brown, red, or yellow brick, which shows perfectly the 

 forms and venation of these fossil leaves. The region is well 

 worth the time and attention of working botanists, both in re- 

 cent and fossil botany; and will doubtless ere long receive its due 

 share of exploration and study, since it has become .so easy of access. 



IPaper /.] 



Aif ANALYSIS OF FILTERED WATER. — JamcS A. Dodcje. 



The question of the ways and means of obtaining sufficiently 

 pure water for drinking purposes and domestic use in this city, is 

 one that has been several times discussed before the Academy and 

 elsewhere. Wo must all admit that it is a question of importance. 



