The Galena and Jfaqitoketa Series. — Sardeson. 27 
the fossils are inseparable from the matrix. When dolomitization has 
taken place, then too few fossils remain. Normally, however, large 
numbers are found in some lamina?, in the upper and middle part, be- 
sides scattered ones throughout. The latter are the less often wanting 
in altered strata. 
The bed is sometimes 23 feet thick, or when reduced, 18_ feet. Again 
the limestone is 15 feet or less, not including two to four feet of clay at 
the base. The maximum thickness is probably the primitive one. The 
stratigraphic position, the coarser structure and one species of fossil, 
Rhyndionella. orientaliH Bill., may be cited as means for determining 
this bed. 
2. Bellerophon bed. 
The new name, Bellerophon bed, is proposed here for the strata in- 
cluded under the name "glass rock" in southwestern Wisconsin. It is 
the lower half of the Lower Blue limestone. 
The lowest stratum is argillaceous, breaks with a conchoidal fracture 
and crumbles when exposed to the weather, and thus forms in most 
cases an easily recognized contrast to the Buff limestone. The rest of 
the bed is more difficult to distinguish by lithologic characters alone. 
It is, however, more uniform and of finer texture than the Buff lime- 
stone, besides containing more fof^sils which commonly make up inter- 
spersed laminae in the rock. The bed is about 12 feet thick at Minne- 
apolis. Minn., but has been vertically compressed. The equivalent 
strata in Wisconsin are 15 feet thick. 
T^e standard of thickness is rarely deceptive. Local alterations of 
the limestone itself are common. The numerous faunal peculiarities, on 
the contrary, are nearly uniform, although difficult to distinguish for 
they are small. Bellerophon wisconsensis Whitf. has not been found 
except'in this bed, and although not abundant is still widely distribu- 
ted. B. bilobattis Sow. is very abundant in the lower half, but appears 
to be totally wanting in the upjjer half. A lithologic division were also 
perhaps practicable. 
3. Stictopokeela bed. 
The upper half of the Lower Blue limestone of southeastern Wiscon- 
sin is elsewhere not simply a limestone. At Minneapolis, Minn., car- 
bonaceous, dark brown or gray crystalline limestone forms the lower 
part of the lied in main, while intercalated clay and shale lamina? at the 
base become thicker upwards and form the main part of the upper 
strata. The bed is less than half limestone. Toward the southeast the 
amount of calcareous material is found to increase finally to the exclu- 
sion of the shale. At Decorah and McGregor, Iowa, the limestone far 
exceeds the marly constituents. At Lancaster and at Platteville, Wis- 
consin, some clayey shale still is found; at Janesville, none. 
The shale laminfe are not uniform, neither are the limestone strata, in 
any locality, but the one encroaches upon the other alternately. The 
characteristic fossils, Stivtoporella frondifera Ulr., associated with 
Rhi/nchonella ainfsliei N. H. W., characterize the shaley portions. The 
limestones are often deeply carbonaceous, and deeper coloring of iron 
