Plate XI. 
Figs. 1 and 2.  Leperditia fabulites, Conrad’ = 4a n7 2 
Ia, 16, Ic and Id, left, end, right, and ventral views of a cemplete 
example of this species, natural size, from Beloit, Wis. 
2. Interior of right valve, from Lebanon, Tenn., x 2, showing the 
two rows of papillze within the ventral edge, the radiately marked 
muscle spot, and the eye spot. 
Fig. 3. -Leperditiaslinneyi, n. sp. -..-. 174 
3a, left valve, x 2, from near Harrodsburg, Ky. 
36 and 3c, posterior and ventral views of same, x 2. 
3d, right valve, x 2; 3¢, anterior view of same, x 2. 
Mig. 4. Weperditiaiumidula, nisp) 175 
4a, 46 and 4c, side, posterior, and ventral views of a right valve, 
x 2, from Danville, Ky. 
Fig. 5. Lepeérditia appressa, ni sp... A 176 
5a, 52 and 5¢, side, anterior, and ventral views of a left valve, x 2, 
from Harrodsburg, Ky. 
5a, outline view, natural size, of a large left valve, from Danville, 
Ky. 
Fig. 6. Leperditia cecigena, S. A. Miller’) 2.32 176 
6a, a large right valve, x 3, showing a small eye spot. 
66, 6c and 6d, left side, posterior, and ventral views, x 3, of a com- 
plete example, of medium size. Both of these specimens are 
from near Madison, Ind. 
Fig. 7. Isochilima,subnodosa, n-sp.)2. | 
7a, 76 and 7c, side, anterior, and ventral views of rather small left 
valve, x 2, from Perryville, Ky. 
Fig, 8. Isochilina ampla, m. Sp 52.92). 179 
8a, 86, 8c, side, anterior, and ventral views of a right valve, natural 
size. Nashville, Tenn. 
8d, interior of another right valve, natural size, showing eye, and 
reticulated musele spot ; Nashville, Tenn. ° 
Fig: 9.: Vshochilina. jonesi, Wetherby 2.9...) seen 179 
ga, 92 and gc, three views of a large left valve, natural size, from 
near Harrodsburg; Ky. 
Fig. ro. Isochilna‘saffordi; n Sp. 53.) 5.0 178 
10a, 106 and toc, three views of a large left valve, natural size, 
from Nashville, Tenn. 
10d, small portion of surface, x 3, showing the grano-reticulate sur- 
face ornamentation. 
Fig. 11. Isochilina Kentuekyensis, n. sp.) 179 
Ila, 116 and IIc, side, anterior, and ventral views, x 2, of a left 
valve, from Mercer Co., Ky. 
11d, ventral spine and small portion of margin, x 4, to show the row 
of small pits. 
Fig. 12.) Usochilinaamianayespr. 0-25 : ae 180 
12a, 126 and 12c, side, end, and ventral views, x 2, of an average 
right valve, from Ottawa, Can. 
Fig. 13. Isochilma amiana, var. dsionis; n. valine 181 
A right valve, x 2, occurring with the typical form of the species. 
