of the Goniatite Limestone of Rockford, Indiana. 171 
very difficult to point out characters by which it may be distin- 
guished.” He thought, however, that, judging from DeKo- 
is Monograph of the Carboniferous Brachiopoda of Scotland, 
that he says the surface is “ covered with minute punctures.” © In 
fact almost every word of Mr. Davidson’s description would ap- 
Michilint from Scotland, sent by Mr. Davidson, we have been 
unable to find any appreciable differences. We are not, how- 
ever, contending that they really are identical, but we simply 
mean to say that it is unsafe to base conclusions upon such 
closely allied species. 
The three subdivisions Prof. Swallow has called Vermicular 
ing at others a yellowish very fine soft argillaceous, 
or arenaceous rock, or consisting of alternations of brownish and 
greenish shaly limestone, &c. The fossils are usually in a better 
state of preservation in the limestones than in the other beds, 
and assume a more decided Carboniferous aspect than in the 
arenaceous and argillaceous strata, even where the latter occur 
above the limestones. 
The Black slate, so far as our knowledge extends, seems to be 
nowhere greatly developed in Missouri, though it is Baim 
ese 
Swallow's Section No. 15, p. 99, of the Missouri Report. ome 
eight or ten miles east of Hannibal, in Illinois, it is seen oceupy- 
with relation to the representative o , 
ably not been very clearly determine 
* Tenth Ann, Rept. Regents University of N. Y., p. 136. 
