340 STRATIGRAPHICAL GEOLOGY. 



fragments. There was nothing in them that would enable us to localize 

 the horizon more definitely than the general term of Helderberg, which 

 is partly Upper Silurian and partly Lower Devonian ; but the fact of the 

 existence of the upper part of the series only at Lake Memphremagog, 

 fifty-five miles distant, led to the opinion that the newly-discovered area 

 was of the same age. Of the second parcel sent, from Fitch hill, Mr. 

 Billings wrote as follows: 



"The fossils came last night. They are Favositcs Gothlandica, a large 

 crinoidal column, a Peutamerns closely allied to if not identical with P. 

 Knightii, and a gasteropod. The first two prove nothing. The Pentam- 

 erus goes far to show that the rock is about the top of the Upper Silu- 

 rian — say Lower Helderberg. The gasteropod is just like some that 

 occur in the same horizon. I do not consider the fossils sufficient to 

 decide the age of the rock very closely, but only that it is either Upper 

 Silurian or Lower Devonian. I have specimens of the Bernardston en- 

 crinites, and will endeavor to determine whether they are identical with 

 yours or not." 



Since then we have obtained large masses of the chain coral, Haly- 

 sites, and probably fragments of the tribolite Lichas. This last discovery 

 seems to be sufficient, coupled with the presence of the Paitavierus, to 

 identify our New Hampshire deposits with the Lower instead of the 

 Upper Helderberg, The chain coral has been considered characteristic 

 of the Niagara limestone, a formation lower than the Helderberg. Its 

 extreme range is from the Trenton to the Lower Helderberg, culminat- 

 ing in the Niagara. Possibly we shall be able to search further for fossils 

 in our Helderberg and other fossiliferous strata, and thus obtain material 

 for a chapter upon paleontology. In that case there may be presented 

 hereafter full descriptions and figures of the genera enumerated above. 



Relations of the New Hampshire and MassacJuisctts Helderberg. An 

 allied rock has long been known at Bernardston, Mass. It was first de- 

 scribed by my father in the Massachusetts report of 1833, with a draw- 

 ing of the crinoidal stems. Quite recently Prof. Dana has described the 

 locality and the adjacent strata,* deducing important generalizations from 

 his observations. The Memphremagog and Bernardston deposits lie on 

 the opposite sides of the same formation, — the calciferous mica schist 



* Avier. Jour. Set., Ill, vol. vi, p. 



