568 C. H. Hitchcock—Helderberg Rocks in New Hampshire. 
of it will appear in Lancaster. A specimen obtained from one 
of the mountains back of the Crawford house seems to hold an 
obscure crinoid in it. More decided is a locality in Kast 
Hanover, where I have found a considerable thickness of slate 
conglomerate. The locality was visited before the first dis- 
covery of the corals of Littleton. I doubt not that scores of 
new localities of the Helderberg will be discovered along the 
Connecticut Valley, as explorations progress, since we now 
know what to look f 
latter very scanty, appears in Lyman, north from the g 
gold mine, upon a hill near D. Knapp’s house. The limestones 
North of Young’s Pond are also irregular Helderberg slates. 
A difficult problem has been propounded by our late dis- 
_ coveries, which cannot be solved satisfactorily without further 
explorations. From the south we carry the auriferous clay 
slates northeasterly, and from the north we trace the Helder- 
berg series of slates in the reverse direction until they meet the 
former. They are so much alike that no effort has been made 
to separate them, and consequently it is impossible to say 
where one ends and the other begins. The boundary line 
must lie between Blueberry Hill and Young’s Pond. 
Swift Water Series. 
While occupied in investigating this subject, I found a set of 
specimens which could not readily be referred to any of the 
series that have been mentioned. I had supposed them to be 
connected with the Lisbon group, but a careful examination of 
the specimens did not tend to confirm this impression. I wi 
nt a section of much importance crossing this and other 
groups, in a northwesterly direction, from Bronson’s limestone 
quarry in Lisbon, through the village, and past the bea 2% 
in Lyman, and nearly past Parker Hill in Lyman. This is the 
route selected for the measurement of the thickness of the Lis- 
bon, Lyman and clay slate series, referred to above. 
_ At the southeast end of the section, there are ordinary 
