2Q2 The American Geologist. May, ]89s 
The species of Agraiihis show narrow range, as do also 
those of Dicclloccphalus, each being found in a single horizon. 
The value of this fauna lies 
1st. In its bearing upon the question of the position of these rocks 
in the geologic scale. 
2nd. In the addition tliat it has made possible to the paleontology 
(if the primitive Gastropoda. 
3rd. In the morphologic series that the different species present. 
4th. In the aid it has given to minor stratigraphic subdivision of 
these formations. 
5th. In the data furnished for use in correlation. 
The general aspect of this fauna is identical or at least 
very similar to the Baraboo fauna described by Whitfield, 
which he referred tentatively to the Oneota of the Magnesian 
series. Evidently the strata from which it was taken must 
belong to a lower horizon at or above the middle of the Basal 
Sandstone series in accord with the possibilities of structure 
pointed out by Irving, for no such excessive vertical range as 
this is found in any locality where the succession of formations 
is clear. But the Taylor's Falls fauna does not strengthen the 
claim to strata of Middle Cambrian age in Minnesota. The 
occurrences of species of Euofiiplialiis, Tiyb/idiiini, Agnmliis, 
Lingiilcpis, Ohokila, HyalitJics, etc., all together, although 
combining to a certain degree characters of both the Middle 
and Upper Cambrian, do not as a whole present a primitive 
faunal aspect. So that whatever may, after more careful ex- 
ploitation, prove, true of those strata represented by the great 
lower sandstone member, it is at least probable that the 
strata represented by the Dresbach shales and all above it 
should be regarded as Upper Cambrian. 
EXPLANATION OF PLATES. 
Plate XVII. 
Figures about natural size. 
Fig. I. C/ieilocep/ialiis xt. croixrnsis, n. sp., (type of genus). P. 2qo. 
Fig. 2. HypseIoco)ius recur'Knis {'^\\\X.i.), var. elongatus, (type of ge- 
nus). P. 284. 
Plate XVIII. 
Geological map of the St. Croix Dalles. The map is intended to lo- 
cate the outcrops of the different rocks in more detail and with greater 
accuracy in the vicinity of the village of Taylor's F'alls than is possible 
on the map of the whole district. The map covers four square miles. 
