5 Ithaca Group 5 



PART I. 



Introduction. 



The more recent studies of the Upper Devonian in New York 

 have shown that some of its five divisions are closely related to 

 each other by their fossil remains. Some of the most characfter- 

 istic fossils of one group often begin to appear in the formation 

 just below it, and to continue, though less abundantly, into the 

 succeeding horizon. It is for this reason often difficult to decide 

 whether a group is more closely related to the beds above or be- 

 low it. In the case of that at Ithaca, opposite views have been 

 held by the two paleontologists best acquainted with it at the 

 typical locality — Prof. Hall including it in the Chemung and 

 Dr. Williams placing it with the Portage. 



The present paper has to offer such data and conclusions on 

 the relations which these faunas sustain to each other as the 

 writer has been able to gather from the detailed study of sever- 

 al secftions near Ithaca. All of the material colle(?ted during 

 this study has been presented to Cornell University and may 

 be found catalogued in the Paleontological Museum. 



Brief Review op the Study op the Upper Devonian in 



New York. 



The basis of the present classification and division of the New 

 York Devonian was developed by the geologists of the New 

 York Survey — Hall, Vanuxem, Conrad and Emmons — during 

 the first ten years of its existence. 



The first attempt to determine the age of the New York De- 

 vonian by means of its fossil remains was made by Prof. Jas. 

 Hall, who stated in 1838 that he considered "the rocks of the 

 4th Distridl as belonging to the Old Red sandstone and the Car- 

 boniferous group and to be above the Silurian system of Mr. 

 Murchison."^'^ 



Prof. Hall first introduced the term Ithaca group in 1839.! 

 As originally defined by him it included the rocks about the 

 south end of Cayuga Lake lying between the Genesee shale, or 

 Black shale as it was first called, and the Chemung. 



In the Report for 1840, J Lardner Vanuxem gave the name 



*2d Ann'l Rep't 4th Geol. Dist., p. 291, 1838. 

 t3d Ann'l Rep't 4th Geol. Dist., p. 318, 1839. 

 J 4th Ann'l Rep't 3d Geol. Dist., p. 381, 1840. 



