142 
BULLETIN OF THE LABORATORIES 
per than point out a few simple facts and certain more or less pre- 
sumptive inferences bearing on that most interesting problem, fur- 
nished by the Azoic system. 
PLATE X. 
Fig. I. Diabase j)orphyrite, No. 1882.] 
Fig. 2. Felsite porphyry, No. 1066. 
PLATE XL 
Fig. I. (No. 1001.) Section of chloritic schist just east of Dog river. A 
closely granular magma of quartz, feldspar and calcite, with large irregular crys- 
tals of calcite (<r), mica flakes {m)., quartz grains (0, and scattered magnetite and 
hematite. 
Fig. 2. (No. looS.) Section lenticular felsite-porphyry, occurring in the 
schist, showing fluidal arrangement of the magma, L. orthoclase and oligoclase. 
0 quartz. 
Azg. 3. Diabase porphyrite (No. 1082.) from southwest coast Michipicoten 
island. (See Plate X, Fig. i.) y. labradorite, a. augite, x. apatite, 3a. portion of 
magma highly magnified, 3b. vesicles from same, 3c. crystals and twins of plagi- 
oclase from same, 3d. isotropous section of apatite from same. 
Fig. 4. From a dyke (No. 1004.) one half mile northeast of Dog river, o. 
orthoclase,/. plagioclase, a. augite, x. peculiar green amorphous grain. Much 
magnetite. 
Fig. 5. Diagram of felsite veins in schist, east of Dog river, (Nos. 1008 and 
1009.) 
Fig. 6. Diagram of contact between Nos. 1019 and 1019a. No. 1019, por- 
phyryritic phase of schist, 1019a. fine-grained diabase porphyrite. 
Fi£. 7. Section through strata at west end of Michipicoten island. C. coarse 
basement conglomerate, F. banded fine-grained sandstone in C. X. Contact zone 
of conglomerate, (cupriferous) 10 feet. T. Amygdaloidal trap, 40 feet. A. vesic- 
ular amygdaloid 33 feet. 
Fig. 8. Hypothetical section through Michipicoten island, along line A-B., 
figure 9. 
Fig. 9. Outline map of Michipicoten island, (not accurate) with position 
of numbers in our series and supposed lines of strike. 
PLATE XII. 
Fig. I. (No. loiib.) Seep. 126. 
Fig. 2. (No. loiia.) Seep. 126. 
Fi^. 3. (No loiic.) Seep. 126. 
