and its associates on Lake Superior. 251 
No. 40. SAME BED? 1. Calcite in scalenohedrons, 2. Dato- 
and perceptibly eaten into. The calcite crystals rest upon a 
granular mass of the same variety of datolite, which is per- 
haps the result of a displacement of calcite. 
No. 41. “ EvERGREEN Buurr.” 1. Quaré prism. 2. Ortho- 
“oe in minute crystals. 38. Calcite in simple and twin scaleno- 
edrons, 
_No. 44. Locaniry Unknown. 1. Prehnite in its characteris- 
tic form. 2. Quartz in prisms on the prehnite. 3. Analcite 
surface highly crystallized. The crystals are transparent 
; 1 ppe ; 
to be confined to it. 2. Calcite, four small slightly yellowish 
semi-transparent rhombohedrons, modified with steeper scaleno- 
hedron faces, lie upon the datolite. 3. Orthoclase, yellowish 
crystals, ,!, of an inch long, are scatte: 
dae specimen, some lying upon the calcite and some upon the 
I 
green to a slight — from the outer oo of po amygdule, 
Without any line o 
i hnite often - 
nterior the pre: eg porade st 
Prehnite is characterized by a radiating structure, starting from 
