THE KIMMSWICK AND PLATTIN LIMESTONES 
199 
in Parastrophia. There is no indication of sinus or fold, the 
specimens being small, but along the anterior margin there are 
traces of short low folds. 
8. Platystrophia shepardi Castelnau 
Plate XXI, jig. 5 
Platystrophia shepardi was figured by Castelnau (Essai Sys- 
teme Silurien FAmerique Septentrionale, 1843, p. 42, pi. 14, fig. 
15) from the magnesian limestone of the Menominee River, near 
its entrance into Green Bay. According to the Geological Map 
of Wisconsin, published in 1911, this exposure near Menominee 
might correspond approximately to the Prosser limestone of 
Minnesota. 
The brachial valve here figured was found at locality 3 in the 
Sanders branch section, in Ralls County, but it occurs also at 
similar horizons at other localities in Ralls and Pike Counties. 
Most specimens are less elongate along the hinge-line, resem- 
bling Platystrophia trentonensis McEwan, from the Prosser of 
Minnesota and Iowa. 
9. Zygospira nicolleti Winchell and Schuchert 
Plate XXIII, jig. 8A, B. 
The largest specimen found so far is 4.6 mm. long, 4.3 mm. wide, 
and has a total depth of 3.2 mm., the pedicel valve being slightly 
more convex than the brachial one. The median part of the 
pedicel valve is angularly arched, and from this median part 
the sides slope strongly downward toward the lateral margins. 
The general surface of the brachial valve is convex; anteriorly 
the median part is depressed into a sinus. Found near the top 
of the Plattin limestone at the Buford Cave, at the Yeager local- 
ity, and elsewhere in Ralls County, Missouri. 
This species is related generally to Zygospira. Externally 
it resembles Protoceuga anticostiensis Twenhofel, from the Rich- 
mond of Anticosti, in the broad anterior median sinus on the 
brachial valve and in the keeled median convexity of the pedicel 
