3i Reviews — Walcotfs Lower Cambrian or Olenelius Fauna. 



add the North-West Highlands; in Norway and Sweden; in Finland; 

 in Bohemia and Bavaria ; in Sardinia ; in Podolia ; in Petchora land 

 and the Ural Mountains. Perhaps the most astonishing part of this 

 new page of early geological history, to the deciphering of which. 

 Mr. Walcott has brought such skill and ability, is that which relates 

 to the fauna, the mei-e names of which, in column, fill four pages. 

 Here is the summary, written in a very compact manner by the 

 author (p. 576). 



RESUME OF THE FAUNA OF THE OLENELLUS ZONE IN AMERICA. 



Classes, etc. 



Numbers. 



Genera. 



Species. 



Varieties. 



Spongia 



Hydrozoa 



Actinozoa 



Echinodermata 



(Trails, Burrows, and Tracks). 



JBracbiopoda 



Lamellibrancliiata 



Gasteropoda 



Pteropoda 



Crustacea 



Trilobita 



Total ... 



4 

 2 

 5 

 1 

 4 



10 

 3 

 6 

 4 

 5 



15 



4 

 2 

 9 

 1 

 6 



29 

 3 



13 



15 

 8 



51 



59 



141 



11 



Uniting all the fossils of this zone found by our English 

 geologists, Drs. Hicks, Lapworth, etc., in Wales and Shropshire ; 

 by Dr. Schmidt in Kussia ; by Profs. Kjerulf, Linnarsson, Torell, 

 Brogger, Holm, Nathorst, and others in Sweden and Norway, and 

 those from the other European localities, the numbers are extremely 

 small, at present, when compared with those recorded on the 

 American Continent ; nevertheless the facias is one that clearly 

 admits of perfect correlation. 



Mr. Walcott is also able satisfactorily to show now that the 

 Olenelius fauna preceded the Paradoxides fauna. "The cause of the 

 abrupt change from the Olenelius to the Paradoxides faunas is not 

 yet fully recognized. While a considerable portion of the genera 

 pass up, very few of the species are known to do so, and in none of 

 the sections has there been found a commingling of the characteristic 

 species of the Lower and Middle faunas " (p. 594). 



" If we attempt to classify the Olenelius fauna by its genesis, an 

 almost impenetrable wall confronts us. That the life in the pre- 

 Olenellus seas was large and varied there can be little, if any, doubt. 

 The few traces known of it prove little of its character, but they 

 prove that life existed in a period far preceding Lower Cambrian 

 time, and they foster the hope that it is only a question of search. 

 and favourable conditions to discover it. As far as known to me, 

 the most promising area in which to search for the Tpve- Olenelius 

 fauna is on the western side of the Kocky Mountains in the United 



