528 C. SCHUCHERT PALEOGEOGRAPHY OF NORTH AMERICA 



are present the Tetragraptus, Dichograptus, and Phyllograptus faunas, all 

 decidedly in harmony with those of western Europe. This same element 

 was recognized by Gurley and recently by Ulrich in Arkansas, where the 

 latter found a fauna very much like that of the lower Arenig and middle 

 Skiddaw of Wales. 



In the Saint John region, New Brunswick, G. F. Matthew has reported 

 the presence of this period in the lower part of his Bretonian, where 

 faunas occur that have a decided Atlantic and European impress. At the 

 base is the Pardbolina spinulosa zone, also, with Lingulella Icevis, Plec- 

 torthis lenticularis, Clitambonites (?) johannensis, and Rafinesquina (?) 

 atava. This is followed by the Peltura scarab ceoides zone, having Agnos- 

 tics bisectus, Parabolina heres, Protopeltura acanthura, Leptoplastus latus, 

 Spha?roptlialmus, Ctenopyge, Dictyonema flabelliforme confertum, Bryo- 

 graptus Tcjerulfl, and Clonograptus ( ?) spinosus. 



In the third zone occur Obolella ( ?) gemmula, Obolus refulgens, Lin- 

 narssonia, Acrotreta, and Dictyomena flabelliforme acadicum. 



The next is the Tetragraptus zone, with Parabolinella, Cyclognathus, 

 Orthoceras, Styliola primceva, Dalmanella ( ?) electra major, Orthis pan- 

 deriana, Bryograptus patens, Dictyonema delicatulum, D. quadr angular e , 

 Clonograptus flexilis, Diclwgraptus logani, Tetragraptus quadribrachia- 

 tus, Didymograptus patulus, and D. indentus. This or the previous 

 horizon, or both, Euedemann has found on Hoosick river, at Schaghti- 

 coke, New York. 



The Canadic of the Atlantic type is also present in eastern Ellsmere 

 land, on the north side of the Archer plateau to the north of cape Sabine. 

 Here, in the dolomite, Schei collected Leptograptus and Anomocare. 



This period is marked by the first appearance of true graptolites, bryo- 

 zoa (though still rare here), ostracods, and asaphoid trilobites. The 

 gastropods and cephalopods, too, are larger and show better development 

 than in the Ozarkic. 



The Canadic closed with a widespread retreat of the waters from the 

 northern and northeastern areas (see the Saint Peter map for area 

 emerged), thus bringing about the Saint Peter emergence, the marine 

 interval being represented in the Ozark region of southern Missouri by 

 the Crystal City sandstone, which is here 0-200 feet in thickness. Ulrich 

 states : "The Saint Peter falls within, or more probably a little more than 

 fills, the gap between the Beekmantown [of the Canadic] and the Stones 

 River" of the Ordovicic system. In most places the record between these 

 two periods is broken. The Saint Peter sandstones of the upper Missis- 

 sippi valley are by some regarded as eolian desert sands, while others look 

 upon them as marine deposits. May they not be the late Canadic rego- 



