New Loicer Silurian Odvacoda. — I'li'lch. 265 
edge of the right valve fits into a groove in the edge of tlie left. 
(See Figs. 7 and VI of plate ix.) 
Formation and locality: This species is very abundant (associated 
with Bryozoa) in the shalj^ part of the Birdseye limestone at High Bridge, 
Kentucliy. Tliese layers are here nearly on a level with the bridge. The 
species also occurs at Frankfort, in the same beds. 
Leperditia mundula, n. sp. 
Plate ix, Figs. \ to 8. 
Length of en ire carapace, 2.6 mm.; hight, 1.64mm.; thiclinet^s. 1.4 mm. 
This species differs from L. fiinitda in being less high, causing 
the outline to be more elongate. In an end view the convexity 
of the valves is also more uniform. A very faintly defined ovate 
area is distinguishable, by depression of the surrounding surface, 
just a trifle in front of the center of the dorsal slope. 
Formation and locality: This form occurred in considerable number 
in a small package of soft shale obtained from the Birdsej^e (? Chazy). 
limestone, near the bottom of the Kentucky river gorge at High Bridge, 
Ky. This bed, which furnished also L. cequilatera and L. germana, is at 
least two hundred and sixty feet beneath tlie L. tumida horizon. 
Leperditia sequilatera, n. sp. 
Plate ix, Figs. 9 to 11. 
Length of entire carapace, 1.7 mm.; hight, 1.03 mm.; thickness, 0.8 mm. 
Carapace rather elongate, with the ends rounded, sub-etjual, 
the back straight, the ventral edge gently convex and nearly par- 
allel with the dorsal. Surface of valves smooth, almost uniformlj^ 
convex, there being only a very slight and quite undefined mesial 
depression in the dorsal slope. 
Distinguished from L. mundula in having the ends of nearly 
equal size and curvature, and the outline in a ventral view more 
uniformly convex, so that the point of greatest thickness is very 
near the middle of the valves. 
Foituation and locality: Same as the last. About forty specimens. 
Leperditia inflata, n. sp. 
Plate jx, Figs, 12 to 15. 
Length of average lel't valve, l.i) mm.; hight, 1.22 mm.; thickness, 
0.54 mm. 
Valves ventricose, the outline usually very much as in L. nijui- 
hitera, only the posterior end is somewhat wider and inflated, so 
that this half of the dorsal region projects more or less beyond or 
above the hinge line. The postero-dorsal angle, also, is more 
