WALCOTT.] EUROPE. 375 



The home of the earliest forms of life seems to have been somewhere towards the 

 southwest, and possibly not far from the equator; and it is from here that the various 

 forms seem to have migrated to the areas in which they were subsequently entombed. 

 The migrations seem to have takeu place towards the North American continent very 

 much about the same time as towards the European ; and the sea encroachments 

 along that continent seem to have been in a direction from southeast to northwest, so 

 that the line indicating the two depressions would meet in mid-Atlantic. This ac- 

 counts for the great similarity in the two faunas and for the general resemblance 

 offered by the order of succession of these early rocks in the two continents. The 

 higher lands in America would be to the west and northwest, and the higher lands 

 in Europe to the east and northeast, so that the last lands submerged would approach 

 each other and occupy the same region of the globe. 1 



The Scandinavian Cambrian series is not over 200 feet in thickness, 

 and represents the entire British series. 2 It is divisible into the Lower 

 Cambrian or Olenellus zone, the Middle Cambrian or Paradoxides zone, 

 and the Upper Cambrian or Olenus zone. 



On the opposite side of the Baltic, in eastern E>toria, the Lower 

 Cambrian zone alone is recognized by the presence of its characteristic 

 fauna. The Middle and Upper Cambiian faunas probably existed in 

 this region, but they have not as yet been discovered. 



Beneath the Paradoxides zone of central Bohemia there is a consid- 

 erable thickness of shales, grits, schists, conglomerates, and quartzites 

 that may represent the Lower Cambrian. TJie Upper Cambrian, if it 

 has not been removed by pre- Silurian erosion, does not appear to have 

 been clearly differentiated from the Middle Cambrian or Paradoxides 

 zone. 3 



The Cambiian rocks of the north of France are correlated with the 

 Cambrian of St. David's, Wales, by authors, but they are not sufficiently 

 well defined by faunas to compare them with American formations. In 

 the province of Herault, in the south of France, the presence of Para- 

 doxides correlates the rocks with the Cambrian of Bohemia. 4 



On the island of Sardinia there is a mixture of Middle and Lower 

 Cambrian faunas, which may arise from the confused state of the strata, 

 or it is not impossible that the faunas are really mingled in the same 

 beds. In the absence of more definite data it is not practicable to com- 

 pare them with the American sections. 



The contrast between the American and European Cambrian, with 

 the exception of the sections of Bohemia aud Sardinia, are not as great 

 as those between the Atlantic Coast Province and the Appalachian 

 Province, or as between the Atlantic Coast and Rocky Mountain Prov- 



1 On tin- deposition of the Cambrian and Lower Silurian rocks. Quart. Jour. Geol. Soc., London, vol. 

 31 . 1875, p. 555. 



2 See Prof. Charles Lapworth's comparative table of the Cambrian rocks of Britain and Scandinavia. 

 "Materials for the Correlation of the Lower Paleozoic Rocks of Britain and Scandinavia." Geol. 

 Mag., new series, dec. If, vol. 8, 1881, pp 320, 321. 



3 Mr. J. E. Marr correlates the basal beds of Barrande's 35tage D (d la) in which Lingvla feist.manteli 

 occurs in abundance, with the Lingula flags of Britain. Quart. Jour. Geol. Soc, London, vol. 36, 1880, 

 p. 602. 



* Bergeron, Jules: Note sur la presence de la Faune primordiale (Paradoxidien) dans les environs 

 de Ferrals-les-Montagnes. Bull. Soc. geol. France, 3 e ser., vol. 16, 1888, pp. 282-285. 



