OP ARTS AND SCIENCES. 



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the lower and middle parts of bed No. 87, and of the chloritic mineral 

 forming the pseudo-amjgdules. 



Both rocks are too highly altered to permit a calculation of the 

 mineral constituents. 



The mineral of the pseudo-amygdules approaches more nearly to 

 delessite than to any other of the chlorites. I have added an analysis 

 of a similar pseudo-amygdaloidal chlorite from another part of the 

 district. 



The amj'gdaloid of this bed is compact — almost aphanitic — in 

 texture, and is reddish-brown to greenish brown in color. Nearly one- 



