Dr. J. W. Webster on St. Michael, &c. 251 
In the rocks which constitute this ledge, are imbedded 
nodules of flint of almost every variety of curvilinear form. 
‘They also abound with petrifactions of shells, &c. &c. 
No. 6. Argillaceous slate inclined at an angle of 45°. In 
every other respect resembling No. 2. 
“No. 7. An alluvial valley. The soil consists of clay, 
mingled with a calcareous mould, evidently the result of the 
decomposition of the rocks in its vicinity. 
No.8. vide No. 2. 
No. 9. — No. 5. ; 
No. 10. Limestone. In this ledge the imbedded masses 
of flint and hornstone are so abundant, as to constitute al- 
most a third. 
No. 11. vide No. 2. 
No. 12. — No. 5. 
No. 13. — No. 2. a 
No. 14. Immense ledges of carbonat of lime, essentially the 
same with that described in No. 5. These form the termi- 
nation of the limestone region, on the E. side of the Cats- 
kill mountains. The geology of the intermediate space is 
perfectly uniform. The rocks are a species of sandstone, 
so fine as scarely to present the appearance of a conglome- 
rate, and with difficulty distinguishable from some of the 
coarser varieties of common slate. At the foot of the moun- 
tain the slate occurs, extremely well characterized, and con- 
tinues. to be the predominant rock for a considerable dis- 
tance up the mountain, when the sandstone again appears,. 
and extends uninterruptedly at least ten or fifteen miles to 
the W. Here my researches terminated. 
Arr. [V.—Notice of a New Work. 
‘¢ A description of the Island of St. Michael, comprising an. 
account of its Geological structure; with remarks on the 
other Azores or Western Islands. Originally communi- 
cated to the Linnean Society of New-England. By Joun 
W. Wesster, M. D. Cor. Sec. L. S$. N.E. Boston ;. 
published by R. P. & C. Williams.” 
Tue Linnzan Society was originally formed bya few gen- 
tlemen of Boston, among whom was the author of this 
