1894. ] NEW YORK ACADEMY OF SCIENCES. 161 
Harrison G. Dyar, “ A Classification of Lepidopterous Larve. 
Harwood Huntington, “Certain New Derivatives in the 
Aromatic Series.” 
The Section of Geology and Mineralogy then organized, Prof. 
Martin continuing in the chair. 
The following papers were read: 
O. P. Hubbard, “ On the Discovery of basaltic Boulders con- 
taining large Nodules of Olivine, at Thetford, Vt.” Dr. Hub- 
bard outlined the discovery of the famous Thetford boulders in 
the early fifties, while he was in the faculty of Dartmouth Col- 
lege. He discussed their probable derivation -from basaltic 
areas in Canada. 
NOTE ON THE PETROGRAPHY OF CERTAIN BA- 
SALTIC BOULDERS FROM THETFORD, VT. 
BY K..O:. Hovey, Pu. 
More than forty years ago Dr. O. P. Hubbard, of New York, 
then of Hanover, N. H., noted the peculiar appearance of a 
large boulder lying in the road as he was driving through the ° 
town of Thetford, Vt., and some time afterward had the rock 
taken to his home, where it lay for some years before material 
from it was sent to the Sheffield Scientific School in New 
Haven. The feature that attracted Dr. Hubbard’s attention was 
the large rounded masses of olivine that gave the rock some- 
what the appearance of a conglomerate. Many other boulders 
of the same character lay scattered over a pasture near the 
place where the first was found, and several years after their 
discovery Dr. Hubbard bought some of these, which the owner 
of the pasture had removed to a neighboring fence, and sent 
them to several museums as a curiosity, but particularly in the 
hope that their origin might be discovered. As is well known, 
the region in which they were found is one of extensive glacia- 
tion, and, in all probability, the boulders were brought from the 
northward to Thetford by the ice. That they were not trans- 
ported very far is attested especially by the fact that they seem 
to have been confined to a very limited area of deposition and 
to thin out in numbers toward the north, according to Prof. C. 
TRANSACTIONS N. Y. AcaD. Sct., Vol. XIII., Sig. 11, May 28, 1894. 
