REVIEWS 279 



from Schoharie county westward are shown to be " a series of arena- 

 ceous lenses connected by thin sheets of quartzitic sandstone." In 

 regard to the fauna of these lenses, it is said : "The great brachiopods, 

 Spirifer arenosus, Rensselaeria ovoides, Hippafionyx proximus, and Meri- 

 stella lata, with Tentaculites elongatus, which are the species generally 

 present in these lenses, could not have had their habitat on such a 

 deposit and in a sea whose depth favored such deposition. We shall 

 not be wrong in regarding these accumulations of remains in the 

 true Oriskany sandstone as agglomerations, swept out of their facies 

 and away from the more calcareous, deeper water deposits of the time. 

 To regard them as species of the sandy facies of Oriskany time would, 

 I believe, be altogether erroneous. They appertain truly to the cal- 

 carious facies and the normal fauna of the Oriskany time." 



In the summation of the fauna, ninety-four clearly defined species 

 are recognized, of which "thirty-eight represent expressions of species 

 which began their existence in Helderbergian time; on the other 

 hand but eighteen species of the fauna continue their existence or 

 appear to be represented by closely allied forms beyond the close of 

 the Oriskany sedimentation." Twenty-nine species of the fauna are 

 recognized in the arenaceous Oriskany beds. 



The evidence afforded by this fauna as the true Siluro-Devonian 

 boundary line is of much importance. No one disputes the Devonian 

 age of the Oriskany formation, and this fauna demonstrates that there 

 is no natural faunal break in passing from the Helderbergian to the 

 Oriskany, as there should be if the Helderbergian was excluded from 

 the Devonian. 



The closing pages of the report are devoted to somewhat minute dis- 

 cussion of the Silurian and Devonian characteristics of the Helderbergian 

 fauna, both the positive and the negative elements being considered, 

 and to a discussion of the stratigraphic argument based upon the rela- 

 tionships of the Maulius limestone. 



S. W. 



