Petrographical Notes on Rocks from Chelsea. 133 



crystals show incipient alteration to calcite. These may be 

 orthoclase, but the rest are undoubtedly plagioclase. 



Augite is also present in considerable quantity, generally in 

 larger individuals. They are often penetrated by crystals of 

 plagioclase thus proving the earlier crystallization of the latter. 



One, basal section is seen showing the characteristic cleavage 

 nearly at right angles, and extinction parallel to the diagonals. 



Some of the olivine crystals have been completely altered 

 to serpentine. Both the olivine, and the serpentine which replaces 

 it, contain inclusions of some kind of iron ore in small grains. 



What is apparently the groundmass of the rock consists of 

 minute slender plagioclase crystals, fine opaque grains probably 

 of iron, and a light-brown glass. This is isotropic in polarized 

 light and tends to give the rock, which has otherwise an ophitic 

 structure, the appearance of a melaphyre. 



On the other hand, while the section examined is in no part 

 quite holocrystallinc, it is very nearly so in several places and 

 is therefore, probably, better classed as an olivine diabase. 



This is a volcanic rock which commonly occurs amongst 

 rocks of all ages from Pre-Cambrian to Mesozoic. 



St. Francis College, Richmond, Que., July 29th, 1896. 



NOTES ON BIRD LIFE IN AUTUMN. 



By Miss A. C. Tyndall. 



Through the late summer and autumn months, there are 

 always odd specimens of our summer visitants to be found in 

 the woods, whom various mishaps and accidents have prevented 

 from going south with their fellows, and though some of them may 

 be able to join their comrades later, the question of the future 

 with the majority resolves itself into that of a lingering death of 



