00 The American Geologist. Jamuu-.v, is97 
Iowa and Wisconsin a deliraitation of this hed has not V)een attein[)ted, 
from iack of suitable observed exposures with fossils to distinguish it. 
S. TilNGULELASMA* BKD. 
This bud is partly extant in Goodhue county, Minnesota, but better 
exposures are found at Concord, Wassioja and Mantorville in Dodge 
county, and on section 26 Hijjh Forest, Olmsted county, and near Wy- 
koflf. Fillmore county, Minnesota. The thickness is between 30 and 35 
feet, and the contacts are not difficult to distinguish, as a rvile, between 
this one and the Caraerella and Maclurea beds. The Lingulelasmabed 
affords a firm limestone, less shaley than the one beneath it and finer 
grained than the one upon it. The upper strata are highly fossiliferous. 
At Dubuque, Iowa, the same is easily recognizable. Linyulelaama ga- 
leiiensis W. and S. is not abundant and occurs moreover also in the Fu- 
coid bed (5) in Iowa. Lingula hurlbuti N. H. W., Oaniarella owatonn- 
ennis Sar. and Plectamboniies gihboHa W. & S., belong to the Lingu- 
lelasma bed. 
9. Maclurea bed. 
Species of Machirea are found in beds of the Beloit formation, but 
not the very large specimens, M. cuneaia Whitf., which are every where 
characteristic of this bed of coarse, porous, dolomitic limestone at the 
top of tfie Galena formation. In all known exposures of the Maclurea 
bed the rock shows alteration, such that internal casts of shells are dis- 
torted or re-imbedded in the matrix, and few fossils except large ones 
are preserved. The thickness is about 35 feet. Good exposures are at 
Wasioja and Stewartville, Dodge county, near Wykoflf, Fillmore coun- 
ty, Minnesota, near Decorah and at Dubuque, Iowa. 
10. Triplegia bed. 
This name is to include what was called Maquoketa shales in my 
former description. It is the top 30 feet of the " Galena formation" at 
Scales MoutTcl, Illinois, and Dubuque, Iowa. At the latter place, the 
contact with the Maclurea bed can be seen. Here the Triplecia bed 
has the thinner strata which same also have shale laminae between 
them. Between Conover and Decorah, Iowa, an exposure shows very 
much more shale than in the first mentioned localities. At Florence- 
ville, Iowa, the contact with the Maclurea bed is again exposed and 
the crinoidal limestone in irregular strata with shale partings there 
seen is characteristic. The middle and upper strata may be seen 
nearby at Granger, Minn., where carbonaceous and argillaceous shale 
predominates in the middle portion and an impure, browinish-gray 
limestone forms the top. The faunal characters place this bed in the 
Maquoketa series. Triplecia ulricM W. and S., Plectainbonites 
j^raicosa Sar, are peculiar to this bed and Ortlris snbquddrafa H. with 
O. kankakensis McChes. are found too. 
*For the spelling of this word see S. A. Miller, North American Geol- 
ogy and Palaeontology. Appendix, p. 689. 
