270 The Ame7'ican Geologist, November, i893 
dorsum are peculiarities that will distinguish this species at once 
from all described Silurian Ostracoda. 
Formation and locality: Very abundant on thin slabs of "Lower Blue" 
or Birdseye limestone collected at Mineral Point, Wisconsin. 
EXPLANATION OF PLATE IX. 
Figs. 1 to 3, Leperditia tumida, n. sp. p. 364. 
1. Right valve, of the usual form, X 10; 2, posterior, and 3, dorsal view 
of same, in outline. 
Figs. 4 to 8, Leperditia mundula, n. sp. p. 265. 
4. Left side of entire carapace, X 10; 5, ventral, 6, anterior view of same 
in outline. 
7. Interior of a left valv-', X 10, showing groove into which the ventral 
edge of the right valve is inserted when the valves are closed. 
8. Diagrammatic sectional view of the ventral portion of the carapace. 
Figs. 9 to 11, Leperditia /BQUilatera, n. sp. p. 265. 
9. Right side, 10, anterior, and ll,ventral view of an entire carapace, X 10. 
Figs 12 to 15, Leperditia inflata, n. sp. p. 265. 
12. Interior of full grown left valve; 13, dorsal view of same, X 10. 
14. Outline anterior view of closed carapace. 
15, A smaller left valve, approaching L. a'.quilatera in outline, X 10 
Figs. 16 to 18, Leperditia germana, n. sp. p. 266. 
16, 17 and 18. Three outline views, side, anterior and ventral, of a left 
valve of this species from Mineral Point, Wis., X 10. 
Figs. 19 to 21, Leperditia sulcata, n. sp. p. 266. 
19, 20 and 21. A right valve, X 10, with outline anterior and ventral 
views of same. 
Figs. 22 and 23, Leperditia sulcata, var. ventricornis, n. var p. 266. 
22. A left valve, X 10; 23, outline of same in a ventral view. 
Figs. 24 to 26, Leperditia ('? Primitia) dorsicornis, n. sp. p. 267. 
24. A left valve, X 10; 25 and 26, outlines of same in anterior and ven- 
tral views. 
Figs. 27 to 30, Schmidtella crassimarginata, n. gen. et sp. p. 269. 
27. Interior of right valve, X 10; 28, exterior of another right valve, 
equally magnified; 29 and 30, anterior and ventral views. 
Figs. 31 to 33, Leperditia granilauiata, n. sp. p. 267. 
31, 32 and 33. Three outline views, side, posterior and ventral, of a right 
valve, X 15. The puncta; of a small part of the surface are shown in 
3L 
Figs. 34 to 36, Leperditia pimbriata, n. sp. p. 268. 
Three outline views of a right valve, X 15. 
Figs. 37 to 39, Leperditia millepunctata, n. sp. p. 268. 
Three outline views, and a small portion of the punctate surface, of a 
right valve, X 15. 
