The Galena and Maquoketa Series. — Sardesoii. 29 
atiou by water which has carried away parts of the calcareous strata 
leaving a marl full of calcareous lumps and of fossils. Livgulce. show a- 
vertical compression of 0.1 to 0.2 of their length. This bed is seen ex- 
posed 15 feet thick here and may be 20 feet in all. ' Fuc.oids' occur at 
this locality at the base of the bed. At McGregor, Iowa, and at Lan- 
caster, Wisconsin, a shaley limestone with few ' f ucoids' repi-esents it. 
At Dodgeville it is changed to a porous dolomitic limestone, not easily 
separable from the Galena beds. At Eockton, 111., part of this bed is 
quarried, and at Beloit, Wis., that part of the " Upi^er Buff Limestone" 
that contains Chwietes iycoperdon auct. (Prasajjora contigua Ulr. 
etc.,) is of this bed; 
The association together of Plectandxmitis sericea Sow., Orihia sub- 
cequnta Con., Rhynchonella increbescenfi Hall (R. ina'qiievalvia C) 
and large Prasopora, is peculiar to the Fucoid bed. 
6. Orthisina bed. 
About 40 feet of strata are included in this bed. At Saint Paul, Min- 
nesota, 20 feet can be seen in place. The first 8 feet of it I formerly 
called Zygospira bed, but the same falls, as now known, truly within 
the zone of Orthisina americana Whitf. and is otherwise not separable 
throughout. Both at Saint Pkul and at Kenyon, Minnesota, the Or- 
thisina bed is like the Fucoid bed at Decorah, Iowa, in that it is 
changed, probably recently, by water jjercolation until clay with 
rounded calcareous lumps represents most strata. Less changed lime- 
stone strata and a few comjjact limestone laminse form the rest of the 
bed. At Saint Paul there are some calcareous oolite and fine ripple 
marks. At Kenyon one finds manganese nodules associated with pol- 
ished, blackened and perforated surfaces of some limestone strata. 
In Olmsted and Fillmore counties this bed is a shaley limestone. At 
Decorah, Iowa, it is firm, gray limestone. The quarries at Ophkosh, in 
eastern Wisconsin, are in this bed. Elsewhere in that state the bed 
forms a part of the typical, cavernous Galena limestone in which few 
fossils remain, so that complete demarcation of this and the next suc- 
ceeding it is rarely possible, and is not needed. In this bed is Orthiiiina 
(Clitand)oniteH) americana Whitf., and Plectambonitea minnesoteiisis 
Sar. begins at its Vjase. 
7. (!amarklla bed. 
Upion the Orthisina bed follow strata of shaley. sometimes carbona- 
ceous limestone, which, however, is not so shaley as the underlying bed 
in the same section. These strata are comparatively unfossiliferous as 
a rule, but crinoidal limestone, brachiopod strata and fossils in large 
numbers do occur. The species kncjvvn from this section have been 
found to occur in the beds npxt lower and higher, and, like the Sticto- 
pora bed (4), this one is characterized more by the absence than the 
presence of peculiar species. SiropJioniena tri!ob(da Owen ranges from 
this bed upwards, and Zygonpira, vpluinii W. and S., is abundant near 
Wykoff, Minnesota. 
At Kenyon, Mantorville, near Pleasant Grove, and at Wykoflf, Minne- 
sota, exposures indicate a thickness in all not exceeding 30 feet. In 
