No. 3.] BILLINGS — ON THE TACONIC CONTROVERSY. 321 



group of rocks forms a chain of low hills, extending nearly the 

 whole length of Lake Champlain, but, iu general, situated several 

 miles inland from the eastern shore of the lake. Dr. Emmons, 

 about thirty years ago, referred this formation to the Medina 

 sandstone. He was followed by other geologists, some of whom 

 included in the formation the Oneida conglomerate and the 

 Clinton. He afterwards came to the conclusion that the rocks 

 in question were about the age of the Calciferous or Potsdam. 

 In his American Geology, published in 1855, he sometimes refers 

 it to the former and sometimes to the latter. The view that it 

 was of the age of the Oneida, Medina and Clinton was, however, 

 maintained by all others. The question was finally determined 

 by the fossils, and to these I shall confine myself. A locality of 

 trilobites had been discovered by the late Prof. Z. Thomps^on in 

 Highgate, near the boundary line, sometime previously to 1847. 

 He pointed out the place to Prof. C. B. Adams, State Geologist 

 of Vermont, who referred some of the specimens to Prof. Hall. 

 The following is his opinion upon them, as it appears in the "Third 

 Annual Report on the Geology of Vermont," by Prof. C. B. 

 Adams, 1847, p. 31: 



^^ Letter from Professor James Hall, on certain Fossils in 

 the Red Sandroch of Highgate. 



Albany, N. Y., September 17th, 1847. 

 <'My Dear Sir, 



I have only now received your letter of the 10th instant, 

 on my return fiom a geological excursion. I examined the fossils 

 and, as far as T can determine they are all of the central portion of the 

 buckler of a Trilobite, with a prominent narrow lobed glabella. The 

 cheeks have been separated at the facial section, so that we have not 

 the entire form of the head. The course of the facial section indicates 

 that it terminated on the posterior m.irgin of the buckler, and the 

 glabeUa*is narrower in front than behind — these two characters are 

 inconsistent with Calymene, Phacops or Asaphus, the common genera, 

 (as well as with several other ,'^ehera) of our strata, but they belong to 

 Conocephalus and Olenus. 1 am inclined to regard this fragment as 

 part of a Conocephalus, of which I have not before detected a frag- 

 ment in our rock. From its isolated character, therefore, I am able 

 to infer little regarding its real geological position. The form known 

 to me most nearly like this one, is ia the Clinton group of this State, 

 I regret that more species could not have been found, or that some 

 forms in the preceding strata could not be obtained to compare with 

 others already known. 

 The meagre information of the two known species of Conocephalus 



Vol. VI. N No. 3. 



