No. 3.] BILLINGS — ON THE TACONIC CONTROVERSY. 323 



we are to be guided at all by paJasontology we cannot regard this 

 rock as lying at the top of the Lower Silurian but at the very base of 

 Barranle's Second Fauna, if not indeed a little lower. It is therefore 

 not the Medina sandstone, but a formation somewhere near the hori 

 zon of the Potsdam. This accords exactly with conclusions drawn 

 from the evidence afforded by the fossils discovered bv our survey at 

 Quebec last year." 



In this paper the formation was first referred to the base of 

 the Lower Silurian on the palaeontological evidence. The follow- 

 ing notice from C. Hitchcock was published shortly afterwards. 

 (See p. 454 of the vol. last cited) : 



" Letter from C. HiTCHCOCK, Esq., on the first observation of the 

 Fossils of the Red Sandstone formation of Vermont, 



" Eds. Silliman's Journal : As a notice of the Conocephalites from 

 the Red Sandrock series in Highgate, Vt., has appeared in your 

 Journal (Second Series, vol. xxxii, p. 232), it is but just to the dead 

 to state who were the original discoverers of this trilobite. By refer- 

 ring to the Third Annual Rept. Geol. Vt., 1847, pages 14 and 31, it 

 will appear that Prof. Z. Thompson conducted Prof. C. B. Adams to 

 Highgate, where both gentlemen procured a large number of these 

 trilobites. They were sent to Prof. J. Hall in 1847 for determination, 

 who gave them the name Conocephalus, the same genus to which Mr. 

 Billings now refers them. At that time the precise po^ition of the 

 Conocephalus was not known. Nor was Prof. Hall able to give more 

 definite information respecting them in 1858 when I showed him the 

 specimens again. 



These trilobites are noticed on pages 339 and 340 of our Third 

 Report on the Geology of Vermont, which will be ready shortly for 

 distribution. 



Amherst, Mass., Oct. 23d, ISGl."' 



From the above I think it will be evident that I was the first 

 to decide the age of the red sandrock on palaeontological grounds. 

 The locality at Highgate is perhaps not exactly of the age of 

 the typical Potsdam, but nearly of that age.] 



4. — Sir R. I. Murchison''s Address. 



tn a paper entitled " On some points in American Geology," 

 published in the Am. Jour. Sci. 2nd series, vol. xxxi, and in the 

 Can. Nat. & Geol., vol. 6, 1861, Dr. Hunt gave an account of 

 the determination of the age of the Quebec group, and introduced 

 Prof. Hall's researches in such a manner that Sir K. I. Murchi- 

 Bou was led to make the following statement in his ** Address to 



