Floristik, Geographie, Systematik etc. 315 



should be sought for in the infavourable climate and in the diffi- 

 culty of receiving a supply of southern species from the neighbou- 

 ring districts. A. C. Ostenfeld. 



Rigg, G. B., Ecological and Economic Notes on Puget 

 Sound Kelps. (Appendix L. Fertilizer Resources. United States, 

 Senate Document N^. 190, 62d Congr., 2d Sess. p. 179—193. 1911.) 



Rigg describes the various factors which determine the dis- 

 tribution of the different Kelps, such as light, depth of water, the 

 rise and fall of the tide, wave impact, tidal currents and opportunity 

 for anchorage. Under economic uses, he discusses plants belonging 

 to 12 different genera. Valuable colored maps of distribution accom- 

 pany this paper. Harshberger. 



Rigg, G. B., Forest Distribution in the San Juan Islands- 

 (The Plant World. XVI. p. 177—182. June 1913.) 



The Island is forested with Pseudotsuga taxifoUa and Pinus 

 contorta. The author finds that the barren treeless portions of the 

 island elevations are characterized by a gravelly bxack soil and 

 the forested portion by a yellow clay soil. He also draws attention to 

 the fact that in some cases the trees va exposed sitaations are wind- 

 swept, and in other cases not, and he thinks it difficult to accept 

 as the Single common cause an influence that shows any consi- 

 derable effect in only one case. He thinks edaphic factors are of 

 importance. Harshberger. 



Shreve, F., A Guide to the Salient Physical and Vegeta- 

 tional Features of the Vicinity of Tucson, Arizona. 

 (Intern. Phyt. Exe. in America. 11 pp. 1913.) 



In Order to give to visiting phj^ogeographers an idea of the 

 Vegetation of Arizona, the author describes the general orogra- 

 phic features of the region, the general climatic features, the soils 

 and the general features of the Vegetation. The most extensive type 

 is found over the levei bajads where Covülea (Larrea) glutinosa is 

 the most common plant. In deeper soil Opuiitia spinosior, 0. fulgida, 

 O. mamillata are found. After rains ephemeral plants appear such 

 as Bouteloua aristoides, Pectis papposa etc. The detrital slopes show 

 Cereus {Caryiegia) gignnteus, Parkinsonia microphylla and Fouquieria 

 splendens. The alluvial plains, where not cleared, have pure Stands 

 of Prosopis velutina, while the river bands and saline depressions 

 have a different Vegetation. 



Beginning with page 6, Shreve describes the Santa Catalina 

 mountains and their Vegetation from 3,000 feet (920 m) up to 7,700 

 feet (2,350 m). In this ascent the desert trees and shrubs are left 

 behind and oaks on north-facing slopes become noticeable at 5000 

 feet (1525 m). At 7,700 feet Pseudotsuga taxifolia and Abies concolov , 

 are in a heavy stand. The physical condition of the mountains is 

 given. Harshberger. 



Shreve. F., Gold Air Drainage. (The Plant World. XV. p. 110— 

 115. May 1912.) 



The paper details observations on the Inversion oftemperature, 

 which is the cause and an effect of cold air drainage in the Santa 



