36 THE PLANT WORLD. 



as Araucarioxylon, and have no living representatives nearer than 

 Chili and the Pacific Islands. 



During the process of f ossilization the trunks of these ancient con- 

 ifers which had fallen and sunk down in the soft mud of the Jura- 

 Trias lake shores became divided into cylinders, from two to rarely 

 more than ten feet in length, so that they can scarcely be called logs. 

 The prehistoric dwellers of the land selected cylinders of uniform 

 size, which were seemingly determined by the carrying strength of a 

 man. It is probable that prehistoric builders never chose more beau- 

 tiful stones for the construction of their habitations than the trunks 

 of the trees which flourished ages before man appeared on the earth. 



This wood agate also furnished material for stone hammers, ar- 

 row heads and knives, which are often found in ruins hundreds of 

 miles from the forest, the vivid colors, no doubt, being very attractive 

 to the ancient people, who made long journeys for the stone. 



The visit to the Petrified Forest was one of the most pleasant ex- 

 periences which has fallen to the lot of the writer during his ethno- 

 logical explorations in Arizona. In the valleys gnawed from the edge 

 of the "bad lands," surrounded by fantastic pinnacles and mesas, lie 

 in chaotic confusion, sections of the fossil trees, too hard for the tooth 

 of time, which has formed the landscape around them. The ground 

 is covered with gaudy fragments, which tempt the traveler to load 

 himself down with specimens, and every step makes one feel that he 

 is in an enchanted land. 



Dr. W. J. Beal calls attention to the fact that the achenes of the 

 arrow-head, bur-reed and water-plantain have corky margins which 

 serve to float them on water. If this is cut off, the achenes sink at 

 once. The achenes of Carex Asa-Grayi and many others found on 

 low lands are surrounded by an inflated sack with which they float and 

 without which they sink, while the upland Sedge, Carex connnunis, 

 and some others have the sack ( perigynium ) fitting tightly, and hence 

 they readily sink in fresh water. 



Prof. L. H. Pammel has just published a valuable contribution 

 [Bull. No. 9, Division of Agrostology, U. S. Dept. Agric] on the 

 "Grasses and Forage Plants of Iowa, Nebraska and Colorado." It is 

 divided into three parts, the first including observations on the physi- 

 cal features of the States named; the second an enumeration of the 

 more important grasses and forage plants arranged alphabetically, 

 with economic notes; and the third is a classified list of the grasses of 

 these States collected by the author during 1895 and 1896. The re- 

 port is enriched by numerous illustrations. 



