FRAGMENTS OF SCIENCE. 



55 



liminary Description of a New Genus and Three 

 New Species of Crustaceans from an Artesian 

 Well at San Marcos, Texas. 108S. Description of 

 a New Genus and Species of Blind Tailed Batra- 

 chian from the Subterranean Waters of Texas. 

 1089. Description of a New Stickleback from 

 the Coast of Maine. 1090. Description of a New 

 Species of Ant Thrush from Nicaragua. 1091 

 Partial List of Birds collected at Altamira, Mexico, 

 by F. B. Armstrong. 109--i. On Some Prepared 

 Parasitic Hymenopterous Insects from Ceylon. 

 1093. An Annotated List of Birds observed on 

 Margarita Island and at Guanta and Laguayra, 

 Venezuela. 1094. List of Coleoptera collected on 



the Tana River and on the Jomboul Ranee, East 

 Africa. 



Taber, C. A. M. The Coming Ice Age. Bos- 

 ton: George H. Ellis. Pp. 94. 



Tilden, J. H. Cursed before Birth. Denver, 

 Col.: (Author). Pp.314. 



White, E. E. A School Algebra. New York: 

 American Book Company. Pp. 894. $1. 



Wilson, Dr. Erastus. La Ensenanza Moderno 

 (Modern Education). Article 24. Hummary of the 

 Papers in the Annals of the Institute of Secondary 

 Instruction of Havana. Havana: Military Print- 

 ing Office. Pp. 14. Distributed. 



'gxvLQmmts of ^tietiJCje. 



A New Classification of Elevation Areas. 



Prof. Hermann Wagner, of Gottingen, one of 

 the best-known geographers and statisticians 

 of Germany, has recently published a new 

 altitude classification of .the 

 earth's surface, which he di- 

 vides into five regions, as fol- 

 lows : The culminating area of 

 the earth's crust, occupying 

 six per cent of the surface and 

 lying altogether above 1,000 

 metres, with a mean height of 

 2,200 metres (or 7,200 feet) 



%Te1ret 

 .SSoo. 



surface, and has a mean depth of 1,300 

 metres (4,300 feet). The oceanic plateau, be- 

 tween the depths of 2,300 and 5,000 metres, 

 occupies no less than 57*3 per cent of the 

 surface, and has a mean depth of 4,100 

 metres (13,500 feet). Finally, the depressed 

 area, deeper than 5,000 metres, is assumed 

 to occupy three per cent of the surface, with 

 a mean depth of 6,000 metres (say 20,000 

 feet). The mean level of the surface of the 

 earth's crust is placed by these calculations 

 at a depth of 2,300 metres, or 7,500 feet, be- 

 low actual sea level. The total area of land 



Wagner's Htpsoqkapiiio Cfbvk. 



above the sea. The continental plateau, oc- 

 cupying all the surface from the 1,000 metre 

 contour line of elevation to the 200 metre 

 contour line of depth i. e., to the margin of 

 the shallow sea border or continental shelf ; 

 it comprises 283 per cent of the surface, 

 and has a mean elevation of 250 metres (800 

 feet) above the sea. The continental slope, 

 from a depth of 200 metres to 2,300 below 

 sea level, covers nine per cent of the earth's 



is worked out at 28 3 per cent and that of 

 sea at 71*7 per cent of the earth's surface ; 

 the ratio of land to water surface is thus 

 1 : 2-54. The accompanying chart is repro- 

 duced from Nature of June 4 th. 



Silk from Wood. According to the Lon- 

 don Times, there is growing up in France a 

 considerable industry, based on the manu- 

 facture of a so-called silk from wood pulp. 



