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[N. S. Vol. XXIX. No. 739 



is known to be distinct, and the Holmia 

 fauna of this province has few, if any, types 

 in common with the Olenellus fauna of what 

 might be called on the whole the Pacific 

 province and its various intracontinental ex- 

 tensions. For that reason it would be well 

 to restrict the term Georgian, and its pale- 

 ontological equivalent, Olenellus fauna, to 

 the Pacific province, and to adopt Matthew's 

 term, Etcheminian (including Coldbrookian) 

 for the Lower Cambric of the Atlantic prov- 

 ince of America and Europe. For the cor- 

 responding fauna the term Holmia fauna 

 should be adopted, since the term Olenellus 

 fauna, now generally applied to this fauna 

 without true Olenellus, is not only incongru- 

 ous, but inevitably misleading; for it implies 

 physiographic conditions which are now 

 known not to have existed."" The Middle 

 Cambric best known is that of the Atlantic 

 province with its Paradoxides fauna. For 

 this, the recognized term Acadian is most ap- 

 propriate. This name, used by Matthew for 

 the lower division of his St. John group, is 

 thus extended to include the lower half of the 

 Johannian, or middle division of that group. 

 It might be desirable to use a distinct name 

 for the Middle Cambric of the Pacific (in- 

 clusive of Appalachian) province, since these 

 provinces were perhaps even more distinct 

 than in Lower Cambric time. The Upper 

 Cambric was for a long time called Pots- 

 damian. Recognizing the unsuitableness (ex- 

 cept in a historic sense) of this name, Wal- 

 cott has proposed Saratogan to replace it. 

 Though much better than the old name, this 

 is still extremely unsatisfactory, because at 

 Saratoga only the upper and in many respects 

 least characteristic portion of the series is 

 known. It is doubtful if the Saratoga section 

 represents more than the Tremadoc division 

 of the European Cambro-Ordovicic transi- 

 tion; and aside from Dicellocephalus, its 

 trilobite fauna scarcely represents the Upper 

 Cambric. 



' It should be noted that the North Scottish 

 occurrence of the Olenellus fauna is clearly dis- 

 tinct from the Atlantic province, as repeatedly 

 pointed out by Geikie. It probably belongs to an 

 Arctic extension of the Pacific province. 



On the Atlantic coast, the upper Johannian 

 and the greater part of the Bretonian of 

 Matthew's St. John group represents a typical 

 Upper Cambric series in close harmony with 

 that of Europe, with which it shows a strik- 

 ing paleontologic correspondence. The best 

 development is on the island of Cape Breton, 

 where its thickness approaches a thousand 

 feet, if it does not exceed that, and where it 

 includes the characteristic faunal zones of 

 Europe. The upper part of the Bretonian of 

 Matthew includes basal Ordovicic beds, the 

 line between this and the Cambric being gen- 

 erally drawn at the summit of the zone with 

 Asaphellus homfrayi, the equivalent of the 

 Tremadoc. This section forms a better 

 standard for the Upper Cambric than any 

 other known in America, and the name 

 Bretonian would be most appropriate for it. 

 Its meaning would have to be extended so 

 as to include the upper part of the Johan- 

 nian of Matthew, which term would then be 

 discarded, while the beds above the Tremadoc 

 horizon should be separated from it. This 

 readjustment would not be very different from 

 that which makes Acadian in its wider sense 

 include the lower half of the Johannian, in 

 addition to the Acadian in its narrower litho- 

 logic sense. Since the provinces of the Upper 

 Cambric were less distinct, one name would 

 suffice, but that should be Bretonian or some 

 other equally appropriate name, rather than 

 Saratogan or Potsdamian. 



The Ordovicic system has undergone a 

 variety of classifications. At present the one 

 generally accepted includes the Beekmantovm 

 and Chazy in the Lower, as Canadian; the 

 Black River and Trenton in the Middle, as 

 Mohawkian; and the remainder as Cincin- 

 natian or Upper Ordovicic. This classifica- 

 tion is out of harmony with stratigraphic and 

 paleontologic facts. Stratigraphically, the 

 Canadian represents some five thousand feet 

 of calcareous strata (where developed to a 

 maximum), while the Mohawkian includes 

 scarcely six hundred feet. The Cincinnatian 

 as now understood is also less than a thou- 

 sand feet thick, and is in part a phase of 

 the Upper Mohawkian. The Canadian in- 

 cludes two distinct faunas, while the faunas 



