i8g4.] 421 [r.riswold. 
carbonate and an orderly arrangement is detected, we should 
expect such arrangement to indicate optical accordance of 
particles, but Mr. Rutley states^ that " the optical oi'ientation is 
not always the same." Furthermore, if such arrangement de- 
pended upon the solution of a mass of carbonate we should expect 
to find it more completely enveloping all the cavities. A re-exam- 
ination of the rock containing carbonate, having this sjiecial point 
in mind, disclosed no orderly arrangement about the carbonate. 
Thus it would seem that the feature so commonly observed in the 
Ouachita stones depended not upon the replacement of the car- 
bonate, but upon the leaching of the carbonate of the cavities 
themselves, and consisted of a slight cementation of the grains 
bordering on the carbonate. 
Nummary of the arguments. The writer does not consider 
that identity of novaculite with a chalcedonic flint is at all estab- 
lished by Mr. Rutley, and the specific gravity argument is rejected, 
so that he would still hold to a quartz composition for the rock. 
Then it would seem just as probable that the original carbonate 
was calcite as that it was dolomite ; also the idea that there has 
not been more carbonate than is evidenced by the cavities seems 
as strong as the opposed one. If a decision concerning the origin 
of the Arkansas novaculites rested upon the points last discussed, 
it would be an unsatisfactory one. The argument from field con- 
ditions seems much more definite ; the fact that various kinds 
of shales grade into novaculites with sandstones present in the 
columnar section favors the idea of mechanical sedimentation, 
while the occurrence of dolomitic strata unchanged to novaculites 
is strongly opposed to the replacement theory. 
Gexebal Meeting, January 2, 1895. 
President W. H. Niles in the chair. Thirty persons present. 
The following paper was read : ^ 
1 Opus cit., p. 386. 
