780 



SCIENCE. 



[N. S. Vol. XXIII. No. 594. 



The bronze age is divided into two epochs. 

 The close of the first corresponds to a former 

 beach elevation of not more than 3.5 meters 

 higher than the present. At the close of the 

 second epoch, the beach line was probably the 

 same as it is now. 



In an interesting table, Professor Br0gger 

 gives the results of his attempt to measure 

 the lapse of time since the maximum post- 

 glacial submergence. His basis of reckoning 

 is as follows: (1) The rate of elevation was 

 about the same at the beginning as at the 

 close; (2) the rate during the middle period 

 of elevation was greater than at the beginning 

 or close; (3) the determining of the position 

 of the beach lines at the beginning and end 

 of the bronze age and at the beginning and 

 end of the closing epoch of the stone age, com- 

 pared with the estimates of archeologists as 

 to the absolute length of the bronze age and 

 the last epoch of stone, gives a standard of 

 measurement for the rate of elevation during 

 the last period of the same. His results are: 

 (a) For the stone age: 



First epoch, 4900-3900 B.C., or 1,000 years. 



Second epoch, 3900-2400 B.C., or 1,500 years. 



Third epoch, 2400-1900 B.C., or 500 years. 

 (6) Bronze age, 1900-500 B.C., or 1,400 years, 

 (c) Iron age, 500 B.C.-1905 A.D., or 2,400 years. 



Total of 6,800 years. 

 According to Sophus Miiller,^ only about 

 4,900 years have elapsed since the beginning 

 of the stone age in Den mark. He places the 

 duration of the first epoch of the stone age at 

 a minimum of 500 instead of 1,000 years, and 

 the beginning of the bronze age at 1200 B.C. 

 instead of 1900 B.C. 



George Grant MacCurdy. 

 Yale Unhtersity, 



New Haven, Conn. 



Catalogue of the Fossil Plants of the Glos- 

 sopteris Flora in the Department of Geol- 

 ogy, British Museum {Natural History). 

 By E. A. Newell Arber. London, 1905. 

 Pp. Ixxiv + 255 ; pi. 8 ; text f . 51. 

 This book as is indicated by the subtitle is 

 a ' Monograph of the Permo-Oarboniferous 

 Floras of India and the Southern Hemis- 

 ' Nordische Altertumskunde. 



phere,' and as such will prove not only a boon 

 to the paleobotanist, but of inestimable value 

 to the student of phyto-geography and the evo- 

 lution of fioras. It will be welcome to the 

 geological workers interested in the corre- 

 lation of those perplexing series of strata so 

 widely distributed in the southern hemisphere 

 and should also be in the hands of those in- 

 terested in Paleozoic glaciation. Locally the 

 work will also have a large economic value in 

 the hands of operators and prospectors for coal 

 in the regions of which it treats. It embodies 

 the first comprehensive treatment of this flora, 

 and contains, not only a critical summary of 

 previous knowledge heretofore widely scat- 

 tered through an immense number of publica- 

 tions, but also embraces considerable addi- 

 tions to our knowledge. 



The oldest assemblage of land-plants suffi- 

 ciently representative to be called a flora is 

 that which appeared during the Devonian and 

 became highly complex in the later Devonian 

 and Lower Carboniferous time. This flora 

 was a cosmopolitan one and discloses a remark- 

 ably uniform character wherever plant-re- 

 mains have been found in the rocks of these 

 periods, from about latitude Y5° north (Elles- 

 mere Land and Bear Island) southward to 

 Australia and Argentina. This flora included 

 representatives of the following orders: 

 Equisetales, Lycopodiales, Sphenophyllalesi 

 Filicales, Cordiatales and Cycadofilicales, the 

 latter possibly including seed-bearing forms 

 (Pteridospermse). In passing upward into 

 the Upper Carboniferous we find three addi- 

 tional orders, the Cycadales, Ginkgoales and 

 Coniferales; none of these however become of 

 real importance until the dawn of the succeed- 

 ing Mesozoic era. With the Upper Carbonif- 

 erous, however, the world-wide uniformity of 

 this ancient flora becomes broken and it is 

 separated into sharply defined northern and 

 southern floras each made up of types belong- 

 ing to the six dominant Paleozoic orders, 

 which present, nevertheless, an entirely differ- 

 ent facies in the two regions. The southern 

 flora, found in strata laid down immediately 

 subsequent to widespread glacial deposits (the 

 Talchir boulder bed of India, the Dwyka con- 



