Brachiocriiu's and Ilerpetocrtnn.s. — Bather. 213 
6. These are so great that, in consequence of other consider- 
ations that lead to the belief that the two sandstones are es- 
sentially the same formation, it is better to consider them as 
one, although manifesting many evidences of disturbance hj 
the eruptive action which prevailed during their deposition 
and later. 
7. The Taconic age, therefore, is represented in the Lake 
Superior basin, as in New England and Newfoundland, by a 
great series of quartzytes and slates and a few limestones. 
8. Those rocks which have been described and mapped as 
Keweenawan embrace three eruptive sj^stems,* separable by 
two erosion intervals marked by basal conglomerates and by 
faunal differences, viz., the eruptives of the Animikie revolu- 
tion, those of the Keweenawan proper, and the eruptives of the 
region of Thunder bay and Black bay. 
9. We may add as a corollary of the foregoing that the 
ocean which covered the spot where North America was to 
exist was subject to forces which acted simultaneousl}^ on a 
very wide extent, producing oceanic deposits of like nature 
and of like succession, in widely separated regions ; and, 
again, that some other widely operating forces caused the 
simultaneous elevation, depression and, finally, the breaking 
of the crust and the escape of vast quantities of basic rock at 
points far distant from each other. 
BRACHIOCRINUS AND HERPETOCRINUS. 
By F. A. Bathek, London, Eng-land. 
The comparison to wliich I desire to direct the attention of 
American palaeontologists seems to me, now that it is once 
made, so obvious that I am quite ashamed of not having noticed 
it before. 
In the '-Paleontology of New York" f Prof. James Hall 
founded a genus JB./•«e^/o^■/•//N^s•, taking as its Xj\^(' a new species, 
B.nodosarius, represented on jjlate V, figures 5-7, and plate VI, 
figures 1-3. The type-specimens were supposed by Prof. Hall 
to be the arms of a crinoid, to which structures tliey do in- 
deed bear a strong external resem])lance. Furtlicr, in the 
*Tlie next paper of this series will describe the youiip:e8t of these 
systems. 
tVol. Ill, p. 118. 
