X¢ll THE PALEONTOLOGY OF MINNESOTA. 
Minneapolis and St. Paul. Here we frequently meet with thin slabs, one sde of which 
may be filled with good specimens of a small variety of Rhynchotrema minnesotensis, Orthis 
dejlecta, Strophomena jilitexta, Rafinesquina minnesotensis and Leperditia fabulites. Perhaps 
ten or twelve other species have been observed in this bed at St. Paul and Minne- 
apolis that may be considered as common, while all the others are rare. It is to be 
noticed also that very few, if any, of the common species are limited to the bed, but that 
nearly all of them are quite as abundant in the succeeding beds of limestone. For this 
reason no paleontological designation is proposed. 
Vanuxemia bed. This designation is proposed for the upper part (about twelve feet) of 
the limestone series at St. Paul and Minneapolis. It is in part equivalent to the ‘‘ Lower 
Blue limestone” of Wisconsin. The upper five feet are full of fossils, preserved, however, 
chiefly as empty molds and casts. Still, on the bed planes, Brachiopoda and other shells, 
as well as trilobites, are often very well preserved. Leperditia fabulites, Rafinesquina min- 
nesotensis, Orthis tricenaria, Clathrospira subconica, Trochonema beloitense, Lophospira con- 
radana, L. serrulata, and Vanuxemia dixonensis are very abundant, and the last four highly 
characteristic of the bed. Vanuxemia obtusifrons, V. sardesoni, Maclurea depressa, Helicotoma 
umbilicata, Conradella triangularis, and Cyrtometopus scofieldi, also are characteristic but 
much less common. j 
In giving ‘‘Formation and locality” of fossils described in this volume, these two 
limestone beds are, as a rule, not separately referred to. It is to be understood, therefore, 
that the designations ‘‘ Trenton limestone” and ‘‘lower limestone of the Trenton forma- 
’ 
tion,” may mean either one or both beds. 
Stictoporella bed. This term applies to the ten feet of shale and limestone (‘‘ lower 
third of the Trenton shales”) resting on the Vanuxemia bed at St. Paul and Minneapolis. 
Here it is a well marked horizon, containing an abundant fauna of which Bryozoa are the 
principal element, no less than thirty-nine species of this class being represented. 
Stictoporella frondifera, S. anguaris, Pachydictya frondosa and Anolotichia impolita are always 
abundant and, as far as known, are to be found only in this bed. Among the interesting 
fossils is a fine new species of starfish, of which three specimens, the largest four inches 
across, were found at Minneapolis. 
The great abundance of Bryozoa, and the fact that nineteen of the thirty-nine species 
pass on into succeeding beds might be considered as good evidence for uniting the Sticto- 
porella bed with the next group rather than with the Stones River group. But this would 
be an error since it is clearly nothing more than the upper member of the Stones River 
group, which, in tracing it northwestward from Beloit and Janesville, Wisconsin, where it 
cannot be distinguished from the ‘‘Lower Blue limestone,” gradually becomes more and 
more shaly. The conditions seem to have been eminently favorable for the development 
of bryozoan types, so it might be expected that many species would be ushered in, that, in 
this region, reached the hight of their development first in the upper part of the next bed. 
The same intimate faunal connection with the succeeding beds is exhibited also by some 
of the other classes of fossils. As shown in the list nearly 44 per cent (42 of 96) of its 
