44 The American Naturalist. [January, 
Basalt Boulders from Thetford, Vt.—A brief description of 
the material of the peculiar basalt boulders discovered by Hubbard at 
Thetford, Vt., is given by Hovey’ in a recent paper. The most con- 
-Spicuous features of the boulders are the large masses of olivine and 
pyroxene scattered through them. The former are in rounded aggre- 
gates with a granular structure. Their composition is SiO, = 40.75, 
FeO = 9.36; MgO = 50.28. The pyroxene nodules consist of the 
remnants of single crystals of a pale green color, and with an extinct- 
ion of 44°. These nodules are in a groundmass composed of augite, 
plagioclase, hornblende and several accessory substances. The augite 
-of the groundmass is brownish-violet in color, and it has the peculiari- 
ties of basaltic augite. 
Maryland Granites.—Keyes® argues the original character of 
much of the epidote in Maryland granites from its close association 
with allanite, which is believed to be an original component of the 
rocks, since it occurs in them as sharply defined crystals completely 
mantled by fresh biotite. It is found also included in crystals of 
-sphene of whose primary nature there can be no doubt. Finally its 
grains are idiomorphic with respect to many of the original rock com- 
ponents with which they are in contact. 
* Trans. N, Y. Acad. Sciences, xiii, p. 161. 
8 Bull. Geol. Soc. Amer., Vol. 4, p. 305. 
