476 ©. H. Hitcheock—Helderberg Rocks in New Hampshire. 
9. Helderberg strata.—These form the proper subject of this 
communication. In brief, they are sandstones, quartzites, con- 
glomerates, hornblende rocks, argillaceous schists, clay and cal- 
careous slates, crinoidal and coralline limestones, siliceous lime- 
stones, and perhaps other varieties. They occupy three areas, 
ich may be termed the Littleton, North Lisbon and Lyman 
terranes. 
all the varieties having been sent to Mr. E. Billings, he has 
written that the brachiopod is closely allied to the Pentamerus 
Knightii of the Lower Helderberg, while the other fossils do 
not as yet afford anything so definite in regard to geological 
equivalency. : 
“The fossils came last night. They are Favosites Gothlandica, 
a large crinoidal column, a Pentamerus closely allied to if not 
the age of the rock very closely, but only that it is either 
Upper Silurian or Lower Devonian. ave specimens of the 
Bernardston encrinites and will endeavor to determine whether 
they are identical with yours or not.” 
Two points of importance suggest themselves in this connec- 
tion. 1, The horizon at Littleton is different from the Helder- 
berg at Owl’s Head, Province of Quebec, which by the included 
Atrypa reticularis has been shown to be the Upper Helderberg. 
It is hence most likely that we have both the Helderberg lime- 
stones in New England, as well as the strata enclosed by them 
in New York. 2. If there is a limit, the facts indicate that the 
Bernardston limestone is Lower Helderberg. That locality 
furnishes only large crinoidal stem fragments, which have here- 
ore been compared with the upper limestone in New York. 
But the Littleton and North Lisbon localities furnish crinoidal 
ents having the same dimensions in company, at the first 
ea named, with a characteristic fossil of the lower division. 
e Bernardston and Littleton localities occupy the same val- 
ley, and are nearer to each other than the former is to New 
York. Hence from present indications the Massachusetts lime- 
stone may be regarded as Silurian instead of Devonian. 
[To be continued.] 
