DIFFUSION OP THF OAJIBEIAN FAUNAS. 



9 



V. — Olenellus — Paradoxides. 



Olbnbllus — Paradoxides. 



* * ■«■ -A- 



■^ -» * -X- 



T I J 



I J I 



REFERENCE. 



Canadian Laurentian continental Nucleus and the " Fundamental Gneiss " of the West of Europe ; 

 supposed to have been emerged land in Cambrian times. Walcott extends the continental 

 area to the south-west (as represented here) ; but Marcou limits it by including the valley of 

 the Mississippi in the Marine area. A narrow gneissic ridge running north-east in France 

 and Germany and ridges on the Atlantic coast of America, both of importance in Cam- 

 lirian times, are not represented here. 



Outcrops of the Olenellus fauna: three in tlie Roclvv Mountain region and four in the Appalachian 

 region in America represented; outcrops also in Scotland, Norway, Sweden and Russia. 



Outcrops of the Paradoxides fauna. The numbers indicate the several sub-faunas of Paradoxides, 

 their chronological sequence and their distribution, as far as known; 2, the Rugulosus sub- 

 fauna; 3, theTessini sub-fauna; 4, the Davidis sub-fauna; 5, the Fordhammeri (the latest) 

 sub-fauna. The sub-faunas are regularly superimposed, the whole series being found in 

 Sweden. 1, The lamellatus sub-fauna is found beneath the other sul>faunas in that part of 

 f^urope where five sub-faunas occur, and in America wliere tliree occur. The colour bands 

 represent only the general range of the tannas, liut the arrows the district where outcrops are 

 found. 



As we luavi' remarked above, Mr. Walcott regards the lauua with Olenellus as a 

 littoral I'anua propagated along shallow shores in sheltered seas. From several of his 

 sections it will be seen that the Olenelli were preserved in certain places whore mud-beds 

 were thrown down on the barren sands which formed the basement sediments to the 

 Cambrian system ; this is the case at many points on the eastern and western slopes 

 of the continent. A similar habit with these trilobites is manifested by those found in 

 the north of Scotland and in Sweden. In Kussia the Olenelli appear in the sandstones at 

 the summit of the Blue Clay ; but as these clays are supposed to have been deposited in 

 rather deep water, the overlying sandstones show us that shallow-water conditions super- 

 vened, and so the littoral habit of the fauna is preserved also in Eussia. 



The fauna which accompanies Olenellus also is indicative of shallow water and shel- 

 tered shores ; there is a preponderance of articulate over inarticulate brachiopods, and a 

 prevalence of gasteropods ; the pteropods are thick-shelled and large, and there are num- 

 bers of calcareous sponges and corals, the latter indicating warm as well as shallow water.' 



'The species of Olenellus with these molluscs, etc., are those wbidi have an ornamentation of reticulated 

 raised lines, not those in which the raised lines are so heavy as to give the surface a pitted appearance. These 

 latter were small species living on sandy shores. 



Sec. IV., 18<J2. 2. 



